Solid-state electrolyte design; Solid-state challenges | Linda Nazar; Jurgen Janek | StorageX

today we're going to take a deep dive into solid-state battery technologies and we're truly delighted to be joined by two of the world's experts on the topic we're joined by today professor Linda and Azhar from the University of Waterloo and by professor Jurgen Yannick from the University of Giessen let me take a brief opportunity to introduce them they are truly leaders in many aspects of battery technology Linda comes from the background of solid-state chemistry and for many decades she has been study the structure property relationship of ionic transport and over the past 25 years she has investigated many different types of battery chemistry ranging from lithium sulfur batteries lithium air batteries lithium ion batteries in terms of cathode chemistry she started all the way from lithium iron phosphate to all the high energy density technologies that is very actively pursued today Linda is a member of the Royal Society she has won countless awards and mentored dozens of students and postdocs who are now doing their independent research elsewhere in the world and I've had the pleasure of knowing Linda since when I was a graduate student and truly amazed that all the contributions that she has made and as I'm delighted to hear from her today Jurgen Yannick comes from the background of physical chemistry and it's very well known for developing many techniques both experimental and computational to understand fundamental prosthesis is happening in redox materials and in the recent 10 years he has made significant contributions to the understanding of solid-state batteries whether there are base on sulfites or oxides and particularly understanding the importance of interfaces within those materials Jurgen is the Dean of biology and chemistry at the university of Giessen he also runs a joint industry lab with cars at the Carswell institute of technology on the bellend lab so without further ado I will like to ask Linda to start her presentation good morning everyone thank you will for that very kind introduction so I'll be talking about design rules for us all those table lecture lights and I put rules in quotation marks because they're not so much rules as perhaps strategies and I would especially like to start off thanking all of the people in my group that did all of the work that made this that is making this possible today so there's been a lot of I'm not going to talk about Paulo state batteries at some Juergen Yonex position but I will just make a brief introduction to the topic and this is an article taken from the Julie inspector about why Toyota's next move is solid-state batteries of course they there's less risk of fire because they don't have flammable electrolyte sails allows for fast charge times and in particular the technology will allow one to stack so the schematically improving energy density by a factor of as much as two to three and The Economist in 2017 asked us all the state batteries will power us all there is a nice article here and say optimistically assumed that electric cars powered by these could be on the road by 2020 well we're not there yet obviously but that's what happens when you're a little too optimistic so follow state batteries rely on super ionic conductors and optimized interfaces and again uragan is going to be talking about those interfaces I'll be talking about the super ionic conductors so the concept is pretty simple we have a positive electrode some high positive potential which is indicated here by red we have a conductive additive typically carbon indicated in black and as a negative electrode we have a negative electrode material indicated in blue again with some electronic additive and the electrolyte runs completely through that cell so the problem is of course developing good solid electrolytes but it's also a problem of the interface the triple phase boundary where at the active material for example the positive electrode lithium ions and electrons have to be simultaneously transported to that active material and that requires very intimate interfaces so while the electric reactivity of the electrolyte is not a concern achieving the simultaneous transport is indeed a challenge and if one has a large secondary particle aggregate that's also a challenge to obtain the the adequate interface so the more specifically there is also issues of chemical stability of the electrolyte with the positive electrolyte there is oxidative stability issues of the electrolyte in the presence of carbon and ultimately one really wants to use lithium or sodium it's one to using a sodium sulfate battery so one used two wants to use a metal attached a metal anode and this presents its own problems because of course many electrolytes are not stable with lithium metal really only garnets are shown to be stable and and still dendrites will form and so that usually requires the incorporation of some sort of protective interface those concepts are summarized in this slide with just a little bit more detail on the challenges so the first point is that composite electrodes with a high active mass are really necessary in order to compete with today's lithium-ion battery so that implies that we have high ionic conductivity of the solid state electrolyte in the order of 5 to 10 milli Siemens and we have this stable interface that I mentioned and low redox activity with the additives the electrolyte itself the membrane needs to have good mechanical mechanical properties and that means that ideally it is a relatively ductile material that will unable dynamic pressure control to be established and again these criteria for conductivity so I won't get into these factors very much I've already explained that lycium metal is using it as a negative it's fairly crucial to really establish commercialization and a competitive edge for these batteries and just a point that I'm thinking you're going to discuss in great is the fact that one needs uniform density over that interface and I would just ask perhaps that glasses might be the answer but I won't have time to talk about them today and ultimately good rate capacity and rate capability are necessary to compete that we might ask ourselves are these sorts of metrics achievable in a solo state battery comparable to that of a lithium-ion so again the performance is limited by kinetics not so much by transport across the interfaces as I think you're gonna we'll be telling you and of course then we also have to consider the scalability of the production of the solid electrolyte so I won't be talking about polymer electrolytes today not because they aren't a viable technology they tend to have conductivity 'z that are a little lower than what are desirable but we work on the sole of inorganic electrolytes this is just a comparison between oxides and sulphides and as you might imagine one obtains better conductivity with the soft anion lattice such as a sulfide with better stability with a hard ana hard anion lattice so examples of oxides include garnets profs kites NASA con tight materials these are all relatively chemicals chemically stable like to chemically stable with a high voltage they're compatible as it said garnets with metallic lithium but they do have this unfortunate rigidity that yeah very high Young's modulus in the order of more than 150 Giga Pascal's and that makes them non conformable and rather difficult to process into cells okay so in the case of sulfides a variety of different materials have been examined these are sensitive to moisture unlike the oxides they have high voltage stability limits they will react with the lithium metal oxide interface which means that server passivating layers are required but they are relatively ductile with a low Young's modulus in the order of eighteen to twenty-five David Pascal's and then a new player on the block our halides and so the halides are also somewhat sensitive to moisture they are encompassed by materials such as Li 3 m CL where m tensed rare earth and also halo spinel so she'll mention at the end of my talk they actually are compatible with most cathode oxides although they're not stable with metallic lithium but they enable cathode alongside materials to be used without a protective coating and they also have the advantage of good ductility and the topic of today's talk I'll be sort of going over many of these materials but I guess one point just to remind you that all of these solace electrolytes have TOI total ionic conductivity with negligible electronic conductivity and effectively that gives the transport number of 1 which is offers real advantages over most liquid ion liquid electrolyte systems which will not have a transport number of anything close to one and often add affinity of 0.4 to 0.5 so in order to achieve good solid electrolytes then you need to have a facile conduction pathway for the mobile ions that means the high number of carriers somewhat flattened energy landscape which I'll be discussing you need to have disorder in the mobile ion lattice and weak interactions with the framework another topic of today's talk and a polarizable anion sub lattice and I'll be talking about the role of anion dynamics and in fact I'll pretty much start my talk with that so the first surprise super ionic sulfide arguably is lithium germanium IO phosphate this was reported by Rio jocano in 2011 and it really opened up the field so this is often quaintly known as el gps because of its formulation and is reported to have ion conductivity in the order of 12 milli Siemens at room temperature and so this makes that conductivity comparable to traditional liquid organic electrolytes and the solid electrolytes are not been affected by the scottie at low temperature which gives them good low-temperature performance at least comparable to liquid electrolytes if not better so this is just a diagram from a recent paper by Rio jocano and Toyota and nature energy in 2000 Eckstein 16 and this is what we call a rag Oh neat lot of power versus energy and it compares all solid-state batteries with a lot of other different technologies lithium sulfur magnesium lithium air conventional lithium ion batteries and you can see that the solid-state batteries perform really rather well under these in this plot especially at high temperature but even under room temperature conditions they show advantages in both terms of power and energy so this is what some promoting all of the excitement in this area so a few years ago when we started looking at these materials we started working on some sodium ion batteries and we were aiming to find a sodium analog 2 L GPS and we discovered this material which is not ice and structural to i2 L GPS but it actually serves as an excellent model and I'll be using in the framework to talk about anion dynamics so it's formulation is an A 11 s and 2 P s 12 you see the similarity in composition with the LGP s but as I said it's a new crystal family and it has both it has ordered PS 4 + SN for tetrahedra showing here in teal and in cobalt blue and it has channels which contain different sodium ions is actually six sodium ions the 60 sodium iron sites in this material and these foreign channels that run along the c-axis and also along the a and the B axis so it's a three dimensionally conductive material you can see that these channels are formed by safe sharing octahedra of the sodium that run in all of those three directions and here's a better depiction of that along the a axis where you can see that this is the window the triangular window with which through which the sodium ions pass there's also an additional site which we call the sodium 6 site which is a cubic site it's not so important so the point here is that the sodium one and sodium two positions are partly occupied these are the ones depicted in sort of a light rose color whereas the other three sodium sites in the lattice or about 95 percent occupied so we have a occupy partially occupied occupied partially occupied alternating type of system our arrangement abilities in the lattice which gives rise to good conductivity in part because we don't there's we lower the energy for defect formation because of these partial vacancies the structure is reported by us in ES and 2018 and at about the same tire just very shortly thereafter by Sophie instead of Stephanie Damon and burn-up Rowling's group so we carried out a mi D a burnisher molecular dynamic studies and to understand sodium transport in this material and you can see this has been sodium on probability density you can see that um there's isotropic conduction as shown by this probability density in all three dimensions and you can furthermore see that the experimental conductivity in one point formerly semen isn't rather very good agreement with that it predicted by the ami d Siri which is 2 point formerly Siemens and similarly the activation energy by theory of 0.2 electron volts is very similar to what we obtain which is about point two four electron volts from experiment so this is a set of three-dimensional super ionic conductor and the diffusion coefficient that we obtained from ami D is about two times ten to the minus eight centimeter squared per second at 300 Kelvin hundreds in all 303 crystallographic directions and that makes it somewhat similar or very similar I should say 2l GPS but just in the L GPS in the the basal plane so one of the as we started to look for other analogs to this system one of the materials we discovered was the antimony analog which is shown here it was reported in chemistry materials at the same time and we expected this to have better conductivity because of its larger cell boy as smaller because of its larger cell volume I have those numbers can be switched compared to the phosphorus so this actually this has the smaller cell volume this has the larger cell volume so you have to switch those numbers the point here is that the conductivity is about half that of the phosphorus analog and the activation energy is much higher than that of the phosphorus analog and this is also borne out by our theoretical calculations and you can see that the either the sulphide or the selenide have a lower activation energy about 0.25 compared to that of the of the antimony analog and the reason for this is actually shown in this these maps so this is these are maps obtained from neutron diffraction data these are called that this is derived from the maximum entropy method often abbreviated as mem and so this is effectively a map of the nuclear density it's obtained from extracting the structure factors from the neutron diffraction data itself and so what you see here for the phosphorus analog is the nuclear density for for example that for the sulfur around the PS 4 groups so this is the red blobs here are the sodium ion density in the structure and this green density at 300k shows the rotational motion of the ps4 group about this phosphorus position and you can see that at 3 Kelvin there is even disorder obtained in that ps4 group where is it 300k that is rapidly rotationally disordered and this is also true of course at 450 K so we see this rotation at 300 words in the antimony analog there is no motion whatsoever at 3 degrees Kelvin a thread 3 Kelvin whereas at 300 K there is only some disorder but not actual rotation so there's a so this provides this is a real contrast between these materials which we wanted to look into in greater detail and that's shown on the next slide and it relates to this long with this concept which was developed um actually long ago and has been recently revisited which is sometimes called the paddle wheel effect and we actually prefer to an may canal an analog or to a revolving door in which the motion of the framework is actually aiding the mobility of the cations just as one passes through a revolving door so just to put things in context the rotation of these anti and tetrahedral moieties and Polyana and materials in for example sulfates or phosphates was located in high-temperature rotor phases these individuals Martin Jansen in particular did a lot of work in this lung fest as well they were implicated at high temperature plastic phase of the sodium phosphate at 600 and in lithium sulfate and quasi electron neutron scattering confirmed this orientate rotational motion at 600 K in work reported by Jensen at all and more recently other using a MIG and other complicated sophisticated techniques I should say have looked at other poly anions such as the close O brains and also the borohydride n a 300 bh4 so these are fairly recent reports but there's it's hard to get direct proof for this coupling between the anion motion and the cation motion and that's what I'll be talking about a little bit more today so RN so coupled with some MEMS which I already showed you this is the rotation of this ps4 group so a couple with the MEMS we give these we carried out these ami D simulations a variety of different temperatures and were actually able to see the onset of this paddlewheel effect so this is just a snapshot of one picosecond snapshot that shows it as this poly anion is rotating the sodium is moving from one position to another in the lattice and so these two processes are coupled if one pauses our one artificially pauses the motion the activation energy for that transport the energy barrier goes up increases to 0.36 electron volts whereas without constraints it is significantly lower of about point two electron volts this is a little bit of a artificial imposition upon the calculation but still it shows the point of of the importance of the pollyanna and rotation to enabling - lowering that activation barrier for transport and the reason for why that activation barrier is lowered is observed when one actually looks at the structure that's a in the picture that I showed you before of the transport along these one-dimensional chains and the point is that as this poly anion in this case the ps4 rotates because it is edge bonded to the sodium octahedron the lattice it literally turns and opens up that window for transport in a transient way so showing here is the antimony in blue and the phosphorous in pink and you can see that that window opens up as the Pollyanna and rotates for the phosphorous compound but it does not open up for the antimony because there is no pollyana and rotation so the window remains effectively closed for the antimony where it opens up in the case of the phosphorous and this is what this is a large in large part what gives rise to the difference in the activation energy and so one can summarize this by saying that the anion rotation flattens the light energy landscape for the cation transport through the structure and as I said lowers that barrier we have also looked at this effect in lithium ion conductors specifically we've compared beta Li three PS four which is a super ionic conductor but only at 200 degrees because the room temperature phase which is the gamma form is a very very poor conductor so it undergoes a phase transition at around 200 degrees or 250 in order to get to the to the beta form we've been able to stabilize a version of this structure at room temperature which has an equivalent roughly 1 million per centimeter conductivity with this is obtained by incorporating lithium and into the structure and adding silicon to replace some of the phosphorus so we're adding lithium and silicon into this ladder and that has the effect of effectively of splitting the lithium site and so the lithium sites in the beta Li 3 PS 4 structure each lithium site splits into two different sites and that is equivalent to effectively increasing the atomic displacement parameter by a large factor so all of and lithium sites are split by one angstrom which is equivalent to effectively increasing the atomic displacement parameter and this increases the lattice considerably the lattice volume and it stabilizes this effectively beta Li 3 PS 4 type structure so this is an entropic Li stabilized lattice with a geometrically frustrated landscape and you can see B in the gamma form which is of Li 3 PS 4 which is a very very poor conductor at 10 to the minus 17 that's percent of a your room temperature there is a amendments map here show that there is absolutely no rotation whatsoever where as you can see that rotation and the high temperature the so-called beta phase at 200 this data was actually collected at 350 and you can definitely see the onset of that rotation and if you compare that with the silicon substituted form you can see the rotation is very evident in this silicon phase at room temperature which is also has about a 1 milli semen conductivity at 30 degrees centigrade so it is a similar effect to what I just described the sodium we again have a transient opening up of this triangular window which is where the lithium ions pass in this structure and so when we pause the rotation the window disappear or diminishes when we let big pollyana and rotate this is through ami d calculation the window opens up and this is what lowers the activation energy barrier and we notice in the power spectrum that we see the same frequency range for that rotation for the rotation of the polly anion groups as we see for the lithium in the in the materials so that is that again is evidence for the coupled mobility and the two-dimensional probability distribution of this phosphorus sulphur to lithium angle and the distance between the sulfur and lithium atoms in the first shell also shows the same sort of effect effectively that shows that the groups are highly localized which signifies a strong correlation between the pollyanna and the mechanics if there was no correlation between Pollyanna and mobility shenana lithium we would simply see this localized in a discreet spot so the fact that this is delocalized is evidence of this this delocalized of this correlation so time is moving on I will switch to flattening the energy landscape this is just a picture of a golf course pointing out that we don't want to get into these little energy traps or these sand traps and I'll talk about the agura tight lattice in this material it is this or this material this is the diagrams of Wolfgang's iris paper you can see the poly anion tetra heater the ps4 groups in this structure with these Frank Casper tetrahedra in which the lithium ions reside in all four corners of the cubic structure and these Frank Casper polyhedra have usually two different lithium sites called a 24g and 48h site this is the 24th G site here the 48 sites are here and this material is quite popular because it formed passivating quantity stable interface with lithium metal because these insulating materials form and are not and do not continually grow this is shown by uragan Jannik and a nice paper and he's going to be talking about that a bit more and this has also been in there's also been an ion dynamics which have been investigating which has investigated pollyana and rotation so there is an inter cage jump in this material which is thought to dominate long-range transport so disorder on either of these two sites will determine the ion conductivity and if that if we have iodine in the lattice though the iodine is localized on the for a site whereas sulphur is on the 4c site whereas in the case of chlorine and bromine there's d localization over those two sites and that gives rise to very high conductivity so my grad student ly danza Ally Danzo discovered that we could make highly conductive iodine's using the antimony version of this material and they have conductivity upwards of 10 milli Siemens per centimeter there shows the diffraction patterns of the antimony the germanium and the tin the silicon germanium and tin analog and the super ionic conductivity is shown here as high as almost 15 milli Siemens for this particular composition and so the point is that when we substitute antimony with the smallest a of åland open which is silicon that gives rise to the highest lithium content as you can see here and that that gives rise to the highest conductivity and grain boundary effects are important this just shows you impedance data where we can separate the bulk from the grain boundary so in fact there is relatively considerably or there is considerable grain boundary effects another is is low conductivity especially when we get to higher values of silicon but of these conditions we can by centering the pellets we can get conductivity upwards of twenty formerly Siemens per centimeter so improving the grain boundary contact certainly increases the ionic conductivity but the bulk is excellent and this is achieved with a very low degree of anion disorder between the sulfide and the iodine so comparing the structures of the pristine a uridine with our silicon and lithium substituted material we see that we have four sites in the case of this new silicon substituted material were only two sites and the pristine material and these are indicated by these arrows and we again this is a cheek with very little anion disorder so the reason for this increase in conductivity is that we have these additional sites which lie between these Frank test for polyhedra using cages that are showing here and so whether we're we would normally have these jumps within the Frank Kasper polyhedra and also some inter cage jumps the addition of these new sites through a fascia in tetrahedron a little hard to see enable this initial pathway and so this allows a concerted ion migration has to take place because we populated effectively these high-energy interstitial sites and this activates a concerted ion migration which was reported by e fame also by Garrett cedar lowers its activation energy for lithium-ion diffusion so we've also looked just briefly as symmetric cells of this electrolyte together with with lithium and we were able to achieve current densities upwards of 0.6 milliamps per square centimeter over as much as a thousand cycles so this again indicates we have a quasi stable interface formed between the security iodide and the lithium likely due to the formation of lithium iodide and perhaps some lithium antimony phases and jörgen Yannick we'll be talking more about those interfaces in the next talk so I'll just end off on some halide materials also in agora dice starting from this claro a euro type when we different strategy here is to increase the halide concentration in this lattice which actually increases vacancy so i working a case will be in Timmons we have a lithium rich agora di't in this case we have a lithium for a euro tight again is that it creates vacancies on the lithium sites about 10 percent and it makes the material chlorine rich and you can see that the chlorine distributes on both sites of 4a and the fourth seat so we're not really increasing that the anion disorder were simply putting more halide into the latter and so the activation energy drops as we add the halide and the conductivity dramatically increases so weird about conductivity of about nine point four four the highest chlorine concentration that we can achieve which is the chlorine one point five phase and that goes up to about 12 milli Siemens for sintered pellets and so this value of 12 is between the highest conductivity of the LGP s phases either this material or this material which were reported in that nature energy 2016 paper that i referred to earlier and the reason for this are obtained from pfg NMR measurements where we actually quadruple the diffusivity these are our experiments done in collaboration with julian guards group at the University of McMaster University and regrads student David Beck and so this is just a plot of the diffusivity obtained from the TFG measurements and you can see it's definitely the highest for the grain-rich faith and the value of diffusivity of 11 times 10 to the minus 12 is actually higher than that in L GPS or in this lithium silicon l GP f-type R now this other type of structure so the diffusivity is about more than three-fold and that basically correlates exactly what the increase in the conductivity that you see plotted here in this bar graph so the take-home messages that the anion disorder and weakened interaction between the mobile ions and the framework lead to a quadrupling in the iron in the ionic conductivity and when we examine this material when we found this material by using CV we could see that there is much less current passed for the chlorine rich versus the pristine AcuRite material especially after this is the first cycle and this is the second cycle so you can see that were forming a passivating layer and we have better anodic stability with due to this higher halide content and so that inspired us to look at pure halide materials and so I remind you of this plot of energy here where our redox potential that we're really trying to stabilize materials at these higher potentials halides are not typically stable with lithium metal and you can see that in this CV that we now have an onset of oxidation that is about 4.3 Lise's both versus the roughly two point five to two point seven which is seen for a typical phosphate so this enables us to obtain coating free cathode so love st. batteries and with development of a new lithium metal halide structure so I will skip over this slide just in the interest of time the point is that we're trying to develop not only solid electrolytes but also coating materials which can have advantages over things such as lithium niobate which are difficult to control the quality of as one puts coatings on cathode materials so lifting metal chlorides are a relatively new player in the field they were actually investigated in 1997 1992 and Andy Sun came up with some nice work on the lithium indium at about the same time that we published work and all right there is a Panasonic paper here cited in advanced materials and but in this work we've got we've substituted zirconium into either the yttrium or erbium structure to obtain conductivity x' upwards of a million per centimeter so these materials this just shows that there are basically Isis structural in the case of the Etrian erbium this shows x equals zero and other is the pure yttrium this shows the Saucony and substitution and you can see that there's a change in phase as we add the zirconium to this lattice and that is concurrent with an increase in the conductivity up to about 1.4 mil a Simmons at the highest levels of X of about 0.4 to 0.5 and other words a cone iam concentration and these are accompanied by a very low electronic conductivity of an order of 10 to the minus 10 and this data is effectively replicated for the for the erbium material so this is a new structure and this just shows the lithium ion conduction pathway so we create a tetrahedral lithium ion site in this lattice shown by lithium 3 as opposed to the pristine material which just has lithium 1 and lithium 2 and so the pathway here is shown in these red arrows it's effectively a one dimensional conductor but there is limited conduction in in the other planes and so this is a bond valence energy landscape map our energy plot and you can see this lowered energy barrier for act for conduction compared to that between lithium 1 and lithium 2 which is upwards of 0.6 so there's lower energy pathway is what enables is conductivity is about what more than one really seaman to be in paint and we then looked at this material with lithium cobalt oxide as a positive electrode this shows the data for the erbium and for the yttrium and you can see that especially in the case of the yttrium we're able to obtain rather good performance electrochemical with as little as fifteen percent of the electrolyte and especially you can see it in the impedance state of the EIS we have reduced charge transfer for the halide compared to the solid electrolyte we're using just lithium phosphate and that's less than one over twentieth so that's really really decrease that interfacial impedance dramatically in the cell I might add to what we're comparing here is the cobalt oxide with either the halide in the cathode or the lithium cobalt oxide with the lithium li3 ps4 in the cathode in both cases were just using Li three keas for as the as the membrane in the cell so a tracer the Hat point 5c and four point tribal window were able to obtain stable cycling capacity and we've since translated this to a new lithium disordered halo spinel which is I think the first in its class the structure is shown here on the left again conductivity zuv on the order of one point five millionths activation energy similar about point three and this shows the data for in NC six to two and for a high nickel and NC material in MC 85 concentration of nickel and in this case we can actually cycle all the way up to four point six volts with reasonable stability over seventy cycles in the case of the high nickel material were obtained we're able to obtain capacities upwards of about two hundred milliamp hours per gram again over roughly seventy cycles and this is in the window up to four point five volts so we're if even though these electrolytes have a thermodynamic stability window that seems to be about four point three clearly there's some kinetic stabilization that they able to take us up to four point five or four point six volt so with that and two minutes left to go in my 35 minutes I'll just briefly summarize by saying that we have some new descriptors established we have I would remind the audience of the need for high ionic conductivity to obtain high current densities the issue with lithium metal does need to be addressed and I highlighted all of these points increasing the vacancy populate strategies to increase conductivity and stabilize interfaces for example with halide materials controlling cation disorder and anion disorder the importance of anion dynamic and pollyanna and rotation which can enhance the conductivity by a factor of two and one solid electrolyte is unlikely going to overcome all of these challenges and so by function or dual electrolytes are probably necessary so with that I'd like to again thank all of the people that did the work I just doing talk and I'd also like to thank people at 1rl who helped us who gotta help us get Neutron diffraction data our colleagues at BASF my entire lab group showing here and BASF and JC's are in particular for their funding and thank you for your attention Linda thank you so much for that deep dive into ionic conduction and Solly electrolytes and we have received more question than we can possibly answer in the short amount of time so as the moderator I have the difficult task of picking out the question for you so forgive me if I take out two difficult questions so let me start with a very high-level question one of our viewers is asking what has been the success in predicting new solid electrolyte via simulations you show some really beautiful work of AB initial MD for understanding transport but could you comment on how that has led to discoveries of electrolyte well that is a very difficult question will and I would say that there's a lot of hope for the predictive capability of simulation but at this point they have generally proven more as a guideline to interesting materials that may be super ionic conductors that try out maybe not to be has they don't have is quite the conductivity that the simulations predict but it does give us some you know kind of a guideline an inner and an approach of strategy or current materials to target even though sometimes as they said the conductivity is not quite what was anticipated Thank You Linda and next set of questions concerned the first part of your talk on the rotation and hopping coupling so the first question is can you expand upon the role of rotation on face stability relative to ionic conductivity I think you showed a quick two figures on this so the question is on the role of rotation to phase stability that's a harder that well as we can that's a very difficult question because we don't really I would say that that answer is not clear in the case of the there are L GPS does not under seem to undergo any Pollyanna and rotation and yet it's a relatively stable material in the case of the lithium and silicon substituted beta L I 3 PS 4 we stabilize that rotor phase down to room temperature but that's really an entropic stabilization in large part because of the because of the fact that we have that the silicon and phosphorus in the lattice but because we are sampling different rotational states of the poly ni and we can see that in the phonon modes there is probably a contribution of that rotation to the overall stability so I would say that there is probably a contribution but he does not completely quantify it or it is not well quantified Thank You Linda and on a related question in terms of the rotation dynamics can you comment on its contribution to the temperature dependence and specifically how does that contribute to the activation energy in terms of both the rotation and the hopping so you're asking if the rotation the rotational dynamics contribute to the temperature dependence effectively as things rotate faster does that does that help desirey aid the conduction we have not yet quantified and we would be doing this with a em ID so we have not quantified the rotational speed so to speak with the effect of the cation diffusion so experimentally of course conductivity is going to go up as a function of temperature but I think what that question is really addressing is is whether or not we have quantified this by AM ID and the answer is we have not okay I'm being told we are almost running out of time but I will squeeze in one last question your talks discuss a lot of the dynamics in terms of the hopping contribution and to to the conductivity but can you also talk about the effect of carrier concentration so in terms of the amount of disorder and what type of dependence do you see of the ionic conductivity on the amount of disorder in the standard ionic conduction picture well of course carrier concentration is extremely important if only portion of the lattice is involved in that conductivity then in the conduction mechanism you don't end up with a very good conductor so the whole the whole approach of disordering liens in the lattice over many different sites for example in the antimony Agora diet is to do just that to increase the carrier concentration so we invoke a larger number of participatory ions in the process and in the case of the halide we actually see a situation where again we in by increasing that by generating new sites for lithium population and then Woking those ions in the pathway we increase the carrier concentration even though in that case some of the lithium ions are immobile and they just form a any mobile framework so the short story is really important Thank You Linda and for our viewers that many who we could not address the questions we apologize but I'm sure Linda will be happy to answer your questions by email if you reach out to her so Linda thank you once more for the deep dive into the solid-state chemistry of ionic conductor a crucial part of enabling solid-state batteries here at Stanford we're very concerned about all aspects of technology translation being in Silicon Valley so I would like to ask the first question on translation and the second question on policy I know this is a bit different than the technology focus of today's talk and the material science and chemistry so my first question to the both of you is about the cost learning curve so we know that the cost of Solus a battery is not known today it is difficult to estimate but if you I can ask you to assume some time into the future commercial activities are becoming more mature commercial products are delivered how do you think solaced a battery can compete with because learning that is in the incumbent technology in lithium-ion batteries so as the costs begin to fall for solids a battery so does lithium-ion battery and that is a very severe and rapid learning curve and you know there is a cost floor for lithium ion battery but there's still considerable room so I was wondering if the both of you can talk about for technology like solace day or maybe other energy technology how do we compete with another technology that is incumbent that's a 50 billion dollar industry that is also learning at the same time hmm well I think this is the same as probably in all other technology fields I think new new solutions always have it I think difficulties in competing with the existing ones of course so we see currently the fight of the electric vehicle with the automotive motor which is more than 100 years in operation and is being further improved so I think in fact I think once the solid-state battery will not have substantial advantages it will be difficult I think really to have in insufficient time the sufficiently steep learning curve to to be also economically competitive I think in the currents at least materials cost of batteries the cathode is the most expensive part and the electrolyte may is only taking a small share of the cost if a solid electrode would change their picture too much then this is already a significant disadvantage so the solid electrode should not be really more expensive which so I think this this is an important point so and I think in the in the fest but class and Germany the cost issue is in fact something we we also deal with we try to understand in fact the cost issue well I'm not an I'm not a specialist in techno economics so probably I'm not the best to answer these things I try to find good solutions and try to understand which route one can go but as I said it's not I would say it's not a simple automatic route for the source a battery but we are really in an early state and of course industry is always impatient I would say but we still need some time but we should of course in order I think to understand economic potential success we should not forget the costs of a cost issues yes and I'm happy if people make solid I would say techno economic models that are reasonable but upscaling changes things so for example I remember that the the solid power guys and I really like their work in the u.s. in last year on the conference they were worried about the price of lithium sulfide because that is a was an important part of the cost of preparing tire phosphates and the recent convert that was not anymore changed was not more mentioned so that must simply means there must have been now there must be a cheap source of lithium sulfide which before that was just a fine chemical so with upscaling often things change and that has to be taken into account and this is Michael Mann maybe Linda has another view on that I think you've described it pretty well your and I think my view would be that the rate of drop in the cost for traditional lithium-ion batteries is slowing to some degree where is it when that rate of change of the de Crockett in other words the rate of the prop is going to be much higher for solid-state batteries and at some point when assumes or when hopes that they may cross over because there is so much more to be learned in solid-state batteries and indeed upscaling of the solid electrolytes is very important and I think we're not at the stage yet of even having defined the ideal solid state electrolyte so I see that coming down that the dropping costs especially with processing cost coming down very rapidly whereas I think we're coming down in lithium ion but at a much more gentle level now sort of scaling out so I think that would be my only additional comment to what you're gonna say Linda and Jurgen thank you for painting this cautiously optimistic picture of course highlighting the role of chemistry behind all that in the few remaining minutes I thought I would turn your attention to the policy side of things and I'm sure there is not a single participant here and our viewers there are free from the pandemic and we have seen some very encouraging and exciting reports where the response to the pandemic is also being coupled to the response to issues of energy and sustainability the European Union for example has announced major initiatives in this area as many other countries I was wondering if the both of you can talk about looking forward what would be your recommendation to the policy makers how the two can be couple in a way to accelerate the recovery and also our advances for clean energy so maybe now aluminum is that's because it's a more difficult question your well you know as Mark Carney has said you know eventually kovat will be controlled but climate change remains the real pandemic that's on the horizon and so to speak so in terms of in terms of establishing sustainability for the future there is obviously no question amongst policymakers I think and scientists alike that electrochemical energy storage is part of that solution and that is ever going to be more important whether we're in a day and age of kovat or not I mean I would say inside perhaps even increasingly more so we're going to have to think about obviously things are going to change at least in the short term and perhaps in the long term but in any case energy policy and sustainable energy policy has to be part of the solution that's that both of that question so I don't know if you're gonna have some fads yeah maybe oh it comes to my money like that yeah oh did I answer your question will or were you after something else no no this is great Linda thank you for sharing that you're gonna yeah I think what comes to my mind is first of all that I think that it may look that that the cove it let's say period helps but I think on the other hand I think at least in Europe we have this very strong trend towards the public transportation and even discussion for free public transportation to all say reduce individual transportation that of course is worth with respect to carbon dioxide or the carbon footprint and I think the COBIT period of course is it's a stride back because people the tendency for more individual transportation so I think it's Europe we see maybe even in the US we see more bikers eat bikers and so I think that's that's not very supportive the trend of more public transportation electric buses I think is a big wave coming with interestingly solid said batteries entering into that with polymer electrolytes I think it's not so simple with the core but it it looks as if that helps to advance alternative things but partly it also leads to strike backs I think juergen do you get a sense within the EU you that there is an injection of funds and resources as a way we start the economy specifically for technology like like batteries and future technology like solar battery yeah absolutely this is the case I think the these big programs that are currently being advanced I think Europe as such so they had the idea really only principle to put I would say really substantial funds into the support I would say of well environmentally benign technologies and things and nothing in Germany also I think the I think there's electric cars are being supported and there is the idea to support I think environmentally friendly this of course always a straddle because of social issues have to be considered but by and large I would say that there is a strong sense for that in Europe yes well I think that goes at that that will also that will definitely also I would say be trends translated into funding yes I'm sure so sounds like there's a combination of push and polls as a result of the pandemic as I think we're all hopeful that the two can be somehow couple between the recovery and also progress for clean technology so we are out of time Linda and Juergen I'd like to thank you once more for joining us from Germany and entertain our viewers with exciting result it's a six-course meal and a really a wonderful journey for the past hour and a half so thank you both very much so just a quick announcement we will have our next symposium also on Friday June 12th the same time 7:00 a.m. Pacific and we will be joined by Professor Clair gray from the University of Cambridge and oh so professor Guren Seder from the University of California Berkeley and they will continue on our excellent theme so far of understanding materials and chemistry for energy storage technology and them on that note like to thank everyone again for participating and we hope to you see you on June 12th thank you very much

Channel: Stanford ENERGY

Views: 4,018

Rating: 5 out of 5

Keywords: Nazar, Linda Nazar, Janek, Juergen Janek, StorageX, Stanford Energy, Stanford Engineering, Precourt Institute for Energy, Chueh, Will Chueh, Batteries, Storage

Id: NbzfEOLNJcc

Length: 56min 29sec (3389 seconds)

Published: Thu Jul 09 2020