Solid-state Rechargeable Batteries Research Articles

Predominantly chain segmental relaxation dependent ionic conductivity of multiphase semicrystalline PVDF/PEO/LiClO4 solid polymer electrolytes

The solid polymer electrolyte (SPE) films comprise poly(vinylidene fluoride) (PVDF)/poly(ethylene oxide) (PEO) blend (75/25 wt/wt%) as host polymer matrix with lithium perchlorate (LiClO4) as ionic dopant for different salt concentrations (i.e., 5, 10, 15, 20, 25, and 30 wt%), and also varying compositional weight ratio PVDF/PEO blends (i.e., 75/25, 50/50, 25/75, and 10/90 wt/wt%) with 25 wt% concentration of LiClO4 were prepared by solution casting at 70 °C. The results obtained from X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy revealed that there is enormous alteration in the α- and β-phase crystals of the PVDF and the size and content of the PEO crystallites, and also the degree of crystallinity of these SPE materials with the variation of salt concentration and the polymer blend composition. Dielectric relaxation spectroscopy (DRS) was employed over the frequency range from 20 Hz to 1 MHz, at 27 °C for the study of the complex impedance, dielectric permittivity, dielectric loss tangent, ac electrical conductivity, and electric modulus spectra of the SPE films. All these spectra were analyzed separately and simultaneously by a novel ‘master curve representation’ procedure to unveil the contribution of various dielectric polarization processes (i.e., electrode, interfacial, molecular (dipolar), and the ionic) and their relaxations which are exhibited with increasing order of frequency and have substantial overlapping with the adjacent processes in these heterogeneous ion conducting materials. The loss tangent spectra of these materials manifest prominent dielectric relaxation peaks which attribute to the cation coordinated polymer chain segmental dynamics. The high frequencies ac electrical conductivity data of all these materials obey the power law, whereas the Nyquist plots of impedance data exhibit reasonably distinguishable bulk and electrode polarization frequency regions for the electrolytes having salt concentration ≥20 wt%. The inverse correlation observed between the relaxation time and the dc ionic conductivity establishes that the transportation of ions is predominantly coupled to the polymer chain segmental motion which assists the hopping between favourable conduction sites in the ion-dipole complexes. The SPE films are comparatively stiffer and have a slightly higher degree of crystallinity when the salt concentration is ≤ 15 wt% and they exhibit distinct dielectric, dc ionic conductivity, and relaxation behaviour as compared to that of the softer and lower crystallinity films having salt concentration ≥20 wt%. These SPE films possess good electrochemical performance and close-to-unity total ion transference numbers. Among these two sets of the SPE films, the maximum dc ionic conductivity was noted 2.01 × 10−5 S/cm at 27 °C for the 75PVDF/25PEO–30 wt% LiClO4 film from the set of different salt concentrations, and 5.61 × 10−6 S/cm for 25PVDF/75PEO–25 wt% LiClO4 film from the set of varying compositions of the polymer blend matrix. The considerable ionic conductivity values of these SPE films at ambient temperature and also their promising electrochemical performance corroborate them as novel ion conductors suitable for the development of solid-state rechargeable lithium-ion batteries.

Building Better Batteries in the Solid State: A Review.

Most of the current commercialized lithium batteries employ liquid electrolytes, despite their vulnerability to battery fire hazards, because they avoid the formation of dendrites on the anode side, which is commonly encountered in solid-state batteries. In a review two years ago, we focused on the challenges and issues facing lithium metal for solid-state rechargeable batteries, pointed to the progress made in addressing this drawback, and concluded that a situation could be envisioned where solid-state batteries would again win over liquid batteries for different applications in the near future. However, an additional drawback of solid-state batteries is the lower ionic conductivity of the electrolyte. Therefore, extensive research efforts have been invested in the last few years to overcome this problem, the reward of which has been significant progress. It is the purpose of this review to report these recent works and the state of the art on solid electrolytes. In addition to solid electrolytes stricto sensu, there are other electrolytes that are mainly solids, but with some added liquid. In some cases, the amount of liquid added is only on the microliter scale; the addition of liquid is aimed at only improving the contact between a solid-state electrolyte and an electrode, for instance. In some other cases, the amount of liquid is larger, as in the case of gel polymers. It is also an acceptable solution if the amount of liquid is small enough to maintain the safety of the cell; such cases are also considered in this review. Different chemistries are examined, including not only Li-air, Li–O2, and Li–S, but also sodium-ion batteries, which are also subject to intensive research. The challenges toward commercialization are also considered.

A sodium-ion sulfide solid electrolyte with unprecedented conductivity at room temperature

Solid electrolytes are key materials to enable solid-state rechargeable batteries, a promising technology that could address the safety and energy density issues. Here, we report a sulfide sodium-ion conductor, Na2.88Sb0.88W0.12S4, with conductivity superior to that of the benchmark electrolyte, Li10GeP2S12. Partial substitution of antimony in Na3SbS4 with tungsten introduces sodium vacancies and tetragonal to cubic phase transition, giving rise to the highest room-temperature conductivity of 32 mS cm−1 for a sintered body, Na2.88Sb0.88W0.12S4. Moreover, this sulfide possesses additional advantages including stability against humid atmosphere and densification at much lower sintering temperatures than those (>1000 °C) of typical oxide sodium-ion conductors. The discovery of the fast sodium-ion conductors boosts the ongoing research for solid-state rechargeable battery technology with high safety, cost-effectiveness, large energy and power densities.

Development of free-standing phosphate/polymer composite electrolyte films for room temperature operating Li+ rechargeable solid-state battery

A free-standing inorganic/polymer composite electrolyte is prepared by the conventional solution casting method, which exhibits good ionic conductivity (~0.36 mS cm−1 at room temperature) and stable capacity retention with enhanced mechanical property. We can realize that the Li+ conductive spherical inorganic electrolyte, Li1.3(Al0.3Ti1.7)(PO4)3, with optimal relative contents is most effective fillers within the composite electrolyte films other phosphate compounds like as LTP and LSTP. Finally, using the resultant composite electrolyte films, we fruitfully demonstrate room temperature operating Li/electrolyte/LiFePO4 cell followed by the stable electrochemical reactions regardless of the filler contents both in polymer-rich (with 1 wt%) and inorganic-rich (with 20 wt%) composite electrolyte.

Poly(vinylene carbonate)-Based Composite Polymer Electrolyte with Enhanced Interfacial Stability To Realize High-Performance Room-Temperature Solid-State Sodium Batteries.

Solid-state rechargeable batteries using polymer electrolytes have been considered, which can avoid safety issues and enhance energy density. However, commercial application of the polymer electrolyte solid-state battery is still significantly limited by the low room-temperature ionic conductivity, poor mechanical properties, and weak interfacial compatibility between the electrolyte and electrode, especially for the room-temperature solid-state rechargeable battery. In this work, a poly(vinylene carbonate)-based composite polymer electrolyte (PVC-CPE) is reported for the first time to realize room-temperature solid-state sodium batteries with high performances. This in situ solidified PVC-CPE possesses superior ionic conductivity (0.12 mS cm-1 at 25 °C), high Na+ transference number (tNa+ = 0.60), as well as enhanced electrode/electrolyte interfacial stability. Notably, the composite cathode NaNi1/3Fe1/3Mn1/3O2 (c-NFM) is designed through the in situ growth of the polymer electrolyte inside the electrode to decrease interfacial resistance and facilitate effective ion transport in electrode/electrolyte interfaces. It is demonstrated that the solid-state c-NFM/PVC-CPE/Na battery assembled by a one-step in situ solidification method exhibits remarkably enhanced cell performances at room temperature compared with a reference NFM/PVC-CPE/Na assembled through a conventional ex situ method. The battery presents a high initial specific capacity of 104.2 mA h g-1 at 0.2 C with a capacity retention of 86.8% over 250 cycles and ∼80.2 mA h g-1 at 1 C. This study suggests that PVC-CPE is a very promising electrolyte for solid-state sodium batteries. This study also suggests a new method to design high-performance polymer electrolytes for other solid-state rechargeable batteries to realize high safety and considerable electrochemical performance at room temperature.

Cobalt nitride embedded holey N-doped graphene as advanced bifunctional electrocatalysts for Zn-Air batteries and overall water splitting

Exploration of cost-effective and highly durable carbon-based multifunctional electrocatalysts for energy conversion and storage devices (e.g., metal-air batteries) is of critical significance. Herein, we present a unique worm-like structure of hierarchically porous nitrogen-doped graphene (N-rGO) embedded with cobalt nitride (Co5.47N) nanoparticles (named as Co5.47N@N-rGO) by tannic acid assisted nitridation method for Zn-air batteries and overall water splitting. Benefiting from the unique worm-like structure to expose more active sites and the synergy advantages of a close contact between Co5.47N nanoparticles and the N-rGO sheets, the Co5.47N@N-rGO exhibits efficient bifunctional catalytic activities toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Notably, Zn-air batteries assembled with Co5.47N@N-rGO-750 show a power density of 120.7 mWcm−2 and excellent cycling stabilities for 330 h in an aqueous electrolyte. More interestingly, when assembled into a flexible solid-state rechargeable Zn-air battery, the Co5.47N@N-rGO-750 displays a specific capacity of 610 mAh gzn−1 and good cycling stability over 40 h. Moreover, the integrated device for water splitting powered by Zn-air batteries is also fabricated by using the Co5.47N@N-rGO-750 electrocatalyst, exhibiting a good gas generation rate. This work offers a new strategy to design and synthesize efficient multifunctional carbon-based electrocatalysts applied in electrochemical devices.

(Invited) Self-Forming High Energy Density Solid State Rechargeable Battery

Solid state batteries are receiving attention due to the possibility of the incorporation of the high energy density of lithium metal coupled with increased safety due to the elimination of flammable organic electrolytes. The lithium/iodine (Li/I2) solid electrolyte battery system has been used successfully for decades as a primary battery to power implantable cardiac pacemakers and has demonstrated an exceptional record of predictability and reliability with high energy density (1536 Wh/L, 560 Wh/kg). This presentation describes the demonstration of a lithium/iodine rechargeable battery based on the use of LiI rich lithium iodide-(3-hydroxyproprionitrile)2 solid state electrolyte. The battery is first assembled fully discharged using only the solid state electrolyte. The LiI is transformed into the active material where, on charge, lithium metal forms at the negative side of the battery and iodine forms at the positive side. To our knowledge, this is the first demonstration of a rechargeable self-forming solid state lithium battery with electrolyte including LiI(HPN)2. Results on cell formation, cycling, Coulombic efficiency as well as electrochemical impedance spectroscopy will be presented. The results show promise for this conceptual approach for achieving high energy density solid state rechargeable batteries.

High-Modulus Hexagonal Boron Nitride Nanoplatelet Gel Electrolytes for Solid-State Rechargeable Lithium-Ion Batteries.

Solid-state electrolytes based on ionic liquids and a gelling matrix are promising for rechargeable lithium-ion batteries due to their safety under diverse operating conditions, favorable electrochemical and thermal properties, and wide processing compatibility. However, gel electrolytes also suffer from low mechanical moduli, which imply poor structural integrity and thus an enhanced probability of electrical shorting, particularly under conditions that are favorable for lithium dendrite growth. Here, we realize high-modulus, ion-conductive gel electrolytes based on imidazolium ionic liquids and exfoliated hexagonal boron nitride (hBN) nanoplatelets. Compared to conventional bulk hBN microparticles, exfoliated hBN nanoplatelets improve the mechanical properties of gel electrolytes by 2 orders of magnitude (shear storage modulus ∼5 MPa), while retaining high ionic conductivity at room temperature (>1 mS cm-1). Moreover, exfoliated hBN nanoplatelets are compatible with high-voltage cathodes (>5 V vs Li/Li+) and impart exceptional thermal stability that allows high-rate operation of solid-state rechargeable lithium-ion batteries at temperatures up to 175 °C.

Effects of CuO on the microstructure and electrochemical properties of garnet-type Li6.3La3Zr1.65W0.35O12 solid electrolyte

The garnet Li7La3Zr2O12 (LLZO)-based oxides have attracted much attention for solid-state lithium (Li)-ion batteries because of high Li ion conductivity and good chemical stability. However, high-temperature sintering at around 1200 °C and a long sintering time above 10 h are normally required to obtain dense LLZO pellets. Dense sintering of solid electrolytes at low temperature or short sintering time is highly desired for developing high-performance solid-state rechargeable batteries. In this work, we investigate the effect of CuO as a sintering aid on the microstructure and electrochemical properties of garnet-type Li6.3La3Zr1.65W0.35O12 (LLZWO) solid electrolyte through conventional solid-state reaction. The addition of a small amount of CuO can effectively lower the sintering temperature of LLZWO to 1120 °C and reduce sintering time to 6 h. The ionic conductivity of the obtained 2 wt% CuO–LLZWO electrolyte is 1.88 × 10−4 S cm−1 at 25 °C and melted metallic Li shows good wetting behavior toward CuO–LLZWO pellets. Moreover, the LiFePO4|2 wt% CuO–LLZWO|Li battery shows a capacity of 144.9 mAh g−1 at 0.1 C and 65 °C. Even at 1 C, the capacity of the cell can remain at 104.7 mAh g−1. This work offers an effective strategy for preparing high-performance electrolytes for solid-state batteries.

MnIII-enriched α-MnO2 nanowires as efficient bifunctional oxygen catalysts for rechargeable Zn-air batteries

The development of highly efficient bifunctional catalysts for OER and ORR is crucial for improving the efficiency of metal−air batteries. Herein we report a high-performance bifunctional oxygen catalyst of α-MnO2 nanowires synthesized using ionic liquid (IL) as the structure-directing agent. While increasing the IL addition enables to gradually transform the reaction products from β-MnO2 nanorods to α-MnO2 nanowires, increasing the reaction time enables to further improve their crystallinity. For both OER and ORR activities, the same trend was found following β-MnO2 nanorods < α-MnO2 nanowires with low crystallinity < α-MnO2 nanowires with high crystallinity, corroborating the view that the crystallographic structure is more determinative on the electrocatalytic behaviour of MnO2 than other contributors such as surface area. The superior OER and ORR activities of the α-MnO2 nanowires are mainly attributed to its large K+-embedded tunnel structure and high MnIII content accompanied with ample oxygen vacancies. Liquid and solid-state rechargeable Zn-air batteries fabricated using the α-MnO2 nanowires demonstrate a high open-circuit potential of 1.51 V, a maximal power density of 166 mW cm−2, superior cycling stability, as well as great potential in powering portable electronics.

Poly(ionic liquid) iongel membranes for all solid-state rechargeable sodium battery

Sodium-ion is seen as one of the most promising alternative technologies to the current lithium-ion batteries. Sodium is cheap and widely available in comparison to lithium, however new electrode and polymer electrolyte materials need to be found to improve the performance and security of sodium batteries. In this work, we show a new iongel electrolyte with excellent properties for an all solid-state rechargeable sodium batteries. This iongel membrane is based on the poly(dimethyldiallylammonium) polyDADMA-TFSI poly(ionic liquid), N-Propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (C3mpyrFSI) and sodium bis (fluorosulfonyl)imide (NaFSI) the salt. PolyDADMA-TFSI can incorporate up to 50 wt% of C3mpyrFSI ionic liquid content in a self-standing membrane with high ionic conductivity. The increasing the NaFSI concentration in this electrolyte was beneficial for the sodium transference number but detrimental for the ionic conductivity of the membranes. The addition of alumina nanoparticles further improved the membrane mechanical robustness without affecting significantly the ionic conductivity. The iongel membranes presented a wide electrochemical window of 5 V thereby supporting sodium electrochemistry as demonstrated by excellent symmetric sodium cell cycling at 70 ᵒC for 60 cycles. Finally, the electrochemical performance of the optimum composition iongel was evaluated in sodium all solid-state battery using a sodium metal anode and NaFePO4 as the cathode material. The cells show good capacity retention with high coulombic efficiency (>97%) at C rates between C/20 and C/5 achieving 110 mAhg−1 at C/20.

Electrochemical performance of Li+-ion conducting solid polymer electrolytes based on PEO–PMMA blend matrix incorporated with various inorganic nanoparticles for the lithium ion batteries

Abstract The electrochemical performance of the nanocomposite solid polymer electrolyte (NSPE) films comprising poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend as host polymer matrix , lithium perchlorate (LiClO 4 ) as dopant ionic salt, and nanosize SiO 2, Al2O3 , ZnO and SnO 2 particles as inorganic nanofillers have been investigated by employing the electrochemical analyzer and precision LCR meter. The linear sweep voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements of the NSPE films have been performed with symmetrical cells of these films at ambient temperature. It is found that these materials have a conduction stability voltage of about 3 V, excellent reversibility performance over 6 V range, the ionic transference number close to unity (> 0.98), and significant value of ionic conductivity (~ 10 –5 S cm–1 ) confirming their suitability as electrolyte/separator for the development of solid-state rechargeable lithium-ion batteries (LIBs). All these electrolyte materials exhibit negative resistance region above the stability voltage in their LSV plots. The electrochemical parameters and the negative resistance properties of these NSPEs are found greatly affected by the crystallinity, particle size, and dielectric constant of the nanofillers. The ionic conductivity of these NSPEs depends on the structural dynamics of inorganic nanoparticles incorporated ion-dipolar complexes of the materials.

Stabilization of cubic Li7La3Hf2O12 by Al-doping

In this paper we report on the stabilization of cubic Li7La3Hf2O12 by Al3+ doping and present a detailed crystal structure study and lithium ion conductivity measurements of the obtained compound. Polycrystalline Al-doped Li7La3Hf2O12 was prepared by a modified solid state method. The compound consists of micrometer size grains encapsulated by a glassy phase, which helps preventing the volatilization of lithium during annealing. Al-doped Li7La3Hf2O12 crystallizes in the garnet-related structure with a cubic unit cell (sp. gr. Ia3¯d (230)). A structural refinement using X-ray and neutron powder diffraction data showed that the Al3+ ions occupy only tetrahedral Li+ sites in the structure. The presence of overextended leading edges of the peaks on the XRD and NPD data is described by the introduction of an additional phase with rhombohedral distortion that occurs through a stretching of the cubic phase along the body diagonal. The activation energy as well as the total conductivity at room temperature are close to values obtained for un-doped cubic Li7La3Zr2O12 and Li7La3Hf2O12 garnets, which make Al-doped Li7La3Hf2O12 a potential candidate for the application as solid electrolyte in solid-state rechargeable lithium-ion batteries.

Communication—Demonstration and Electrochemistry of a Self-Forming Solid State Rechargeable LiI(HPN)2 Based Li/I2 Battery

While solid state electrolytes hold promise for safer batteries, the lithium/solid-state electrolyte interface has presented challenges. Herein, we report a fully self-forming solid state rechargeable battery based on the Li/I2 couple using LiI rich lithium iodide-(3-hydroxyproprionitrile)2 electrolyte. Effective charge-discharge cycling was demonstrated, showing promise for future generations of high energy density self-forming, self-healing batteries.

Design and Optimization of Novel Alkali Superionic Conductors

All solid-state rechargeable alkali-ion batteries are a safer, potentially more energy dense architecture for energy storage. The crucial enabling component is the non-flammable alkali superionic conductor solid electrolyte, which must possess high alkali ionic conductivity, excellent phase stability, electrochemical and mechanical compatibility with the electrodes, and ideally, stability under ambient air. Despite recent advances, the total number of known alkali superionic conductors remain relatively small, and most have significant compromises. In this talk, we will propose several promising novel alkali superionic conductor solid electrolytes - Li3Y(PS4)2 and Li5PS4Cl2 - identified using an efficiently-tiered first principles screening approach. These candidates are inspired by the observation that many known alkali superionic conductors have analogues in the silver thiophosphate chemical space (e.g., Li7P3S11, the Li6PS5X argyrodites, etc.). We will also present evidence that these candidates may potentially have a better balance of properties, especially with regards to phase and electrochemical stability, compared to current state-of-the-art superionic conductors such as Li10GeP2S12, Li9.54Si1.74P1.44S 11.7Cl0.3 and Li7P3S11.

Challenges and issues facing lithium metal for solid-state rechargeable batteries

The commercial use of lithium metal batteries was delayed because of dendrite formation on the surface of the lithium electrode, and the difficulty finding a suitable electrolyte that has both the mechanical strength and ionic conductivity required for solid electrolytes. Recently, strategies have developed to overcome these difficulties, so that these batteries are currently an option for different applications, including electric cars. In this work, we review these strategies, and discuss the different routes that are promising for progress in the near future.

Toothpaste-like Electrode: A Novel Approach to Optimize the Interface for Solid-State Sodium-Ion Batteries with Ultralong Cycle Life.

A non-sintered method with toothpaste electrode for improving electrode ionic conductivity and reducing interface impedance is introduced in solid-state rechargeable batteries. At 70 °C, this novel solid-state battery can deliver a capacity of 80 mAh g-1 in a voltage range of 2.5-3.8 V at 0.1C rate using layered oxide Na0.66Ni0.33Mn0.67O2, Na-β″-Al2O3 and sodium metal as cathode, electrolyte and anode, respectively. Moreover, the battery shows a superior stability and high reversibility, with a capacity retention of 90% after 10 000 cycles at 6C rate and a capacity of 79 mAh g-1 is recovered when the current rate is returned to 0.1C. Furthermore, a very thick electrode with active material mass loading of 6 mg cm-2 also presents a reasonable electrochemical performance. These results demonstrate that this is a promising approach to solve the interface problem and would open a new route in designing the next generation solid-state battery.

Solid-Oxide Rechargeable Fe-Air Battery Using Fe Modified with Cr-Ni-PrBaMm2O5 for Low Temperature Operation

Recently, rechargeable battery with large capacity is strongly required for storage electric energy from wind or solar cell power generator. For this purpose, Sodium-surfer (Na-S) battery and redox flow battery are now considered because of the high capacity and efficiency. However, Na-S battery has disadvantage of safety issues because molten Na and S are used. On the other hand, redox flow battery is low energy density. On the other hand, iron is non-toxic, highly safety, and rich in natural resource and compatible for environment. So, solid oxide Fe- air battery is also highly interesting for large scale battery for energy storage. Fe-air solid state rechargeable battery was studied by several groups and this battery is consisted of reversible solid oxide fuel cell and redox media consisting of Fe. By using H2/H2O as a redox mediator, high cycle life is expected. However, up to now, operating temperature of the cell is as high as 1073 K because Y2O3 stabilized ZrO2 is widely used. In our previous study, we investigated the solid state Fe-air battery using LaGaO3electrolyte and reasonable charge and discharge property was demonstrated at 873K. In this study, in order to operate the cell at lower temperature than 773 K from efficiency, catalyst used for Fe oxidation and reduction was investigated and it was found that Fe oxidation can be occurred at much lower temperature by mixing Ce0.6Mn0.3Fe0.1O2 (CMF) and the capacity of 600 Ah kgFe -1, was achieved at 673 K by using CMF mixed Fe powder. However, the capacity is 50% of theoretical capacity and also decreased with cycle number of charge and discharge. Detail analysis of internal resistance suggests that overpotential of fuel electrode became larger with increasing cycle number. In particular, diffusion resistance of the fuel electrode is much increased suggesting that the aggregation of Ni-Fe particle is occurred. Since aggregation of Fe in Ni-Fe fuel electrode seems to be main reason for decreased discharge capacity, Ni mixed with Sm doped CeO2 was applied for fuel electrode. It was found that the cycle stability of charge and discharge was much increased when Ni-SDC was used for anode and discharge capacity of 600 Ah kgFe -1 was stably sustained over 30 cycles. In spite of small degradation of the cell when H2 is used for fuel, discharge potential was still slightly decreased with cycle number and this may suggest that H2 formation rate by oxidation of Fe decreases with cycle number. So, in this study, optimization of catalyst mixed with Fe as energy storage media was further investigated for increased cycle stability of solid state Fe-air battery using LaGaO3based oxide electrolyte. Among the catalysts investigated, stable cyclic redox property of Fe powder was achieved by mixing Cr, Ni, and PrBaMn2O5(PBMO). Fe powder with Cr and Ni and PBMO has high redox rate, stability and high oxidation degree and stable redox property was sustained over 50 cycles at 673 K. By applying Fe powder modified with Cr, Ni, and PBMO, the cell shows reasonably large discharge capacity and stable cyclability. This study reveals that combination of reversible SOFC with Fe modified with 5 wt% Cr-1.5 wt% Ni-1.5 wt% PBMO as an energy storage media is a new type of battery with large capacity.

Challenges and Issues Facing Lithium Metal for Solid State Rechargeable Batteries

Research on lithium metal combined with polymer electrolyte in lithium rechargeable batteries was started in 1979. Since that time, lithium battery research has expanded worldwide. Several new polymers, solid electrolytes and ionic liquids with improved conductivity were identified. These advances resulted from a better understanding of the major parameters controlling ion migration, such as favorable polymer structure, phase diagrams between solvating polymers and lithium salts, and the development of new lithium counter-anions. In spite of the progress so far, the quest for a highly conductive dry polymer at room temperature is still not available. However, effort is continuing, and all-lithium polymer battery (LPB) developers presently face the challenge of whether to heat the polymer electrolyte to enable high-power performance, as required for electric vehicles and energy storage. LPB developers have explored both the high-temperature and low-temperature options. The commercial use of lithium metal/polymer batteries has been delayed because of the adverse effects of dendrites on the surface of the lithium electrodes, and the difficulty in finding a polymer that has both the mechanical strength and ionic conductivity required in a solid electrolyte. However, recent strategies have emerged to overcome these difficulties, and now these batteries are currently an option for different applications, including electric cars.In this presentation, we review these strategies and discuss the different promising routes that should result in further progress on lithium metal/polymer batteries in the near future. This presentation also discusses the challenges and opportunities in developing thin lithium negative electrodes with stable SEI layers for three battery technologies using: All solid-state Li-sulfur batteries Rechargeable lithium batteries containing dry polymer and ionic liquid-polymer electrolytes 3. Li-air batteries. In addition, we will discuss the safety of lithium, dendrite mechanism, interface phenomena, side reactions, protection of lithium metal, and lithium alloys that are relevant to lithium batteries. Acknowledgement: The author thanks the SCE IREQ and LTE Shawinigan teams for helpful discussion.

Solid State Li Ion Batteries with Monocarba-Closo-Decaborate Solid Electrolytes

Solid state rechargeable batteries with high energy and power density as well as safety, reliability and long cycle life remain a long standing goal for the energy storage community. While many solid electrolytes have recently been demonstrated with ionic conductivities approaching those of liquid electrolytes at room, few have been integrated into full batteries with competitive power performance. Recently, we discovered a novel class of superionic solid electrolytes, whose facile cation conduction pathways are enabled by the spacious, vacancy-rich, interstitial network created by a sublattice of polyhedral, orientationally mobile, monocarba closo-borate anions and which form salts with alkali metals, LiCB11H12 and LiCB9H10 [1, 2]. These electrolytes exhibit conductivities of ~10-5 S/cm at room temperature and ~0.03 S/cm at 345 C. In this talk we will describe the fabrication and testing of complete batteries consisting of thick film LiCoO2 cathodes with theoretical capacity of ~1.5 mAhrs/cm2 and metallic Li anodes. 1. W. S. Tang, A. Unemoto, W. Zhou, V. Stavila, M. Matsuo, H. Wu, S. Orimo, and T. J. Udovic, Energy Environ. Sci., 2015, doi: 10.1039/c5ee02941d. 2. W. S. Tang, M. Matsuo, H. Wu, V. Stavila, W. Zhou, A. A. Talin, A. V. Soloninin, R. V. Skoryunov, O. A. Babanova, A. V. Skripov, A. Unemoto, S. Orimo, and T. J. Udovic, Adv. Ener. Materials, in review.