A Study of solid state energy storage devices

2024

Solid-state batteries have garnered attention due to their potentiality for increasing energy density and enhanced safety. One of the most promising solid electrolytes is garnet-type Li7La3Zr2O12 (LLZO) ceramic electrolyte because of its high conductivity and ease of manufacture in ambient air. The complex gas-liquid-solid sintering mechanism makes it difficult to prepare LLZO with excellent performance and high consistency. In this study, an in-situ Li2O-atmosphere assisted solvent-free route is developed for producing the LLZO ceramics. First, the lithium-rich additive Li6Zr2O7 (LiZO) is applied to in-situ supply Li2O atmosphere at grain boundaries, where its decomposition products (Li2ZrO3) build the bridge between the grain boundaries. Second, comparisons were studied between the effects of dry and wet routes on the crystallinity, surface contamination, and particle size of calcined powders and sintered ceramics. Third, by analyzing the grain boundary composition and the evolution of ceramic microstructure, the impacts of dry and wet routes and lithium-rich additive LiZO on the ceramic sintering process were studied in detail to elucidate the sintering behavior and mechanism. Lastly, exemplary Nb-doped LLZO pellets with 2 wt% LiZO additives sintered at 1,300 °C × 1 min deliver Li+ conductivities of 8.39 × 10-4 S cm-1 at 25 °C, relative densities of 96.8%, and ultra-high consistency. It is believed that our route sheds light on preparing high-performance LLZO ceramics for solid-state batteries.

In this review work it has been tried to briefly summarize solid state electrolytes conductivity status. As the very essential component for battery efficiency and performance, electrolytes need be given due attention as safety problems could also emanate from it as well. The oxide solid state electrolytes are very promising electrolytes for allsolid-state batteries for large applications. The garnet-structured Li 7 La 3 Zr 2 O 12 has shown high ionic conductivity that is comparable to the liquid electrolytes with large potential windows. At lower temperature Li 7 La 3 Zr 2 O 12 will have high Li-ordered and forms the tetragonal structure which is less ionic conductor as compared to the less Li-ordered cubic structure. A total ionic conductivity of the order of 10 -3 Scm -1 has been achieved by the cubic structures of Li 7 La 3 Zr 2 O 12 which will let it to be applicable in practice.

ChemistryOpen

Frontiers in Energy Research, 2021

With the development of smart electronics, a wide range of techniques have been considered for efficient co-integration of micro devices and micro energy sources. Physical vapor deposition (PVD) by means of thermal evaporation, magnetron sputtering, ion-beam deposition, pulsed laser deposition, etc., is among the most promising techniques for such purposes. Layer-by-layer deposition of all solid-state thin-film batteries via PVD has led to many publications in the last two decades. In these batteries, active materials are homogeneous and usually binder free, which makes them more promising in terms of energy density than those prepared by the traditional powder slurry technique. This review provides a summary of the preparation of cathode materials by PVD for all solid-state thin-film batteries. Cathodes based on intercalation and conversion reaction, as well as properties of thin-film electrode–electrolyte interface, are discussed.

Recent progress indicates that ceramic materials may soon supplant liquid electrolytes in batteries, offering improved energy capacity and safety. W idespread adoption of electric vehicles (EV) will require dramatic changes to the energy storage market. Total worldwide lithium-ion (Li-ion) battery production was 221 GWh in 2018, while EV demand alone is projected to grow to more than 1,700 GWh by 2030. 1 As economies of scale have been met in Li-ion battery production, price at the pack level has fallen and is expected to break $100/kWh within the next few years. Li-ion batteries are expected to address near-term energy storage needs, with advances in cell chemistry providing steady improvement in cell capacity. Yet Li-ion batteries will eventually approach the practical limits of their energy storage capacity , and the volatile flammable liquid electrolyte in Li-ion cells requires thermal management systems that add cost, mass, and complexity to EV battery packs. Recent progress demonstrates that Li-ion conducting solid electrolytes have fundamental properties to supplant current Li-ion liquid electrolytes. Moreover, using solid electrolytes enables all-solid-state batteries, a new class of lithium batteries that are expected to reach storage capacities well beyond that of today's Li-ion batteries. The promise of a safer high-capacity battery has attracted enormous attention from fundamental research through start-up companies, with significant investment from venture capitalists and automakers. The Li-ion battery The 1970s marked development of the first Li-ion cathode intercalation materials. Cells with a metallic lithium anode were commercialized in the 1980s, but it was soon discovered Solid-state batteries: Unlocking lithium's potential with ceramic solid electrolytes that lithium deposits in dendritic structures upon battery cycling. These dendrites eventually grow through the separa-tor, connecting the anode and cathode and causing a dangerous short circuit of the cell. The solution was to replace the lithium anode with a graphite Li-ion host material, thereby producing the modern Li-ion battery. First introduced by Sony in 1991, the graphite anode is paired with a LiCoO 2 cathode and flooded with a liquid organic electrolyte with dissolved lithium salt. The dissolved lithium provides Li-ion transport within the cell. A thin and porous polymer separator prevents physical contact between the anode and cathode while allowing ionic transport between electrodes. This basic cell structure remains unchanged today, albeit with numerous energy-boosting innovations, including silicon anode additions, electrolyte additives to increase cycle life, and high nickel-content cathodes. These innovations have led to an average of 8% annualized energy density improvement in Li-ion batteries. 2 Despite this progress, the volumetric energy density of Li-ion batteries can only reach a practical limit of about 900 Wh/L at the cell level. For Li-ion batteries, active cathode and anode powders are mixed with binder and cast on a current collector using doctor blade, reverse comma, or slot die coating. These electrodes are slit into desired dimensions, interleaved with a separator, and either wound-as is the case of an 18650 (18 mm diameter; 65 mm length) cylindrical cell-or stacked or folded to produce a prismatic pouch cell. Figure 1 shows 18650 cylindrical wound cells and 10-Ah pouch cells. For EV applications, cells are arranged into modules, which are placed into a battery pack. For example, a Tesla Model 3 contains more than 4,000 individual cylindrical cells, producing about 80 kWh of storage. Other manufacturers , such as GM, use pouch-type cells, with 288 cells producing 60 kWh of storage in the Chevy Bolt. Li-ion battery packs contain significant battery management systems to keep cells within a safe operating range. Heat generated within the pack must be removed by cooling systems to protect both the performance and lifetime of Li-ion cells. Credit: Evan Dougherty/University of Michigan Engineering Communications and Marketing Induction coils heat a die for rapid densification of Li-ion conducting Li 7 La 3 Zr 2 O 12 ceramic solid electrolyte.

Small Methods, 2018

liquid electrolytes (LEs) has brought safety hazards associated with the leakage and flammability of organic LEs, especially in Li-O 2 batteries with an open system. [2] Another intrinsic drawback of using LEs in Li-O 2 batteries is the undesired and inevitable formation of Li dendrites, which is mainly triggered by the inhomogeneous Li ions distribution on the surface of Li metal due to the high electric field near tips (commonly known as "tip effect"). [3] This is a common problem in Li metal batteries. Whether the problem can be resolved properly directly determines the practicality of Li metal. Moreover, the evaporation of LEs and their failure in inhibiting O 2 crossover are also serious concerns that hamper the development of Li-O 2 batteries. [4] In this context, replacing organic LEs with (quasi) solid-state electrolytes (SSEs) is a strategy to overcome these shortcomings and achieve high safety. [5] Among the possible candidates, ceramic SSEs are shown to suppress Li dendrite growth, but most of reported ceramic SSEs feature relatively low ionic conductivity and high interfacial resistance with electrodes, in turn leading to deterioration of electrochemical performance. In particular, the drawbacks would be exacerbated in Li-O 2 batteries which intrinsically feature sluggish electrochemical dynamics. [6] Meanwhile, most ceramic SSEs are chemically unstable against Li metal. [7] Alternatively, polymer SSEs show additional advantages in scalability and processability, but they usually require operation at higher temperatures than room temperature, which will increase the difficulty and complexity of the operation condition and may trigger more side reactions in Li-O 2 batteries. [5c,d,7,8] For the development of safe solid-state Li-O 2 batteries, all these drawbacks need to be overcome. Gel polymer electrolytes (GPEs), combing the high ionic conductivity of LE and the mechanical properties of polymer SSE, have drawn considerable attentions for being used as both electrolyte and separator. [9] Besides, GPEs can render the energy storage devices with adjustable shapes and high flexibility, which is promising for the burgeoning portable and wearable electronics. With these merits, GPEs have been reported to be used in Li-O 2 batteries and show relatively improved Development of Li-O 2 batteries with ultrahigh theoretical energy density is highly desired to meet the ever-increasing demand of energy density. However, safety concerns and cycling life have become main bottlenecks that inhibit the practical applications of Li-O 2 batteries because of the use of organic liquid electrolytes (LEs) and the noneffective air electrodes. Gel polymer electrolytes (GPEs) are reported to be used in Li-O 2 batteries and show relatively improved performance than LEs, but they are still below the expectation. Herein, a quasi-solid-state Li-O 2 battery constructed with a GPE and a high-efficiency air electrode is proposed. Excellent electrochemical performance is demonstrated beyond the batteries with LE, evidenced by the ultralong cycle life of up to 553 cycles and stable operating time for over 1100 h. The elongated cycling life benefits from the role of GPE in blocking O 2 crossover, protecting Li metal, and avoiding electrolyte evaporation compared with LE. It is expected that the present study can shed light on the future study on developing efficient catalysts for (quasi) solid-state Li-O 2 battery. Lithium-Oxygen Batteries

ACS Applied Energy Materials, 2019

is a promising solid-state electrolyte due to its wide electrochemical stability window and high Li-ion conductivity. This electrolyte has potential to be employed in the form of thin films for solidstate batteries, a promising approach in the quest for safer batteries with higher energy densities at lower fabrication costs. In this study, we use a scalable cosputtering process to fabricate LLZO thin films with subsequent postannealing at a temperature of 700°C, significantly below the sintering temperatures employed in ceramic pellet processing. We investigate the roles that Li excess and incorporation of Al play in the film's crystalline phase, microstructure, phase stability, and, ultimately, ionic conductivity. Our results reveal that improving the conductivity of LLZO thin films requires not only the stabilization of the cubic phase but especially the densification of the film and the minimization of the proton exchange degradation mechanism in the presence of moisture and CO 2. These issues can be mitigated by effectively controlling the amount of Li and incorporating Al as sintering agent. An ionic conductivity at room temperature of 1.9 × 10 −5 S cm −1 was achieved with a 400 nm Al-substituted LLZO thin film. Finally, we prove that these LLZO thin films can be successfully deposited and crystallized on a LiCoO 2 cathode.

Electrochemistry, 2014

This article summarizes our research on solid electrolytes for rechargeable aqueous lithium-air batteries. Aqueous lithium-air batteries have potential application as a power source for electric vehicles, because of their high specific energy density. A water-stable lithium ion conducting solid electrolyte is the key material for lithium-air batteries to use lithium metal in aqueous circumstance. In this article, two types of lithium ion conducting solid electrolytes, NASICON-type Li 1+x A x Ti 2−x−y Ge y (PO 4) 3 (A = Al, Fe) and garnet-type Li 7−x La 3 Zr 2−x A x O 12 (A = Nb, Ta) are introduced, and the conductivity behavior of these solid electrolytes by elemental substitution, their chemical stabilities in water and electrochemical stabilities with lithium metal are discussed. Lithium ion conductivities of 1.3 × 10 −3 and 5.2 × 10 −4 S cm −1 at 25°C were observed in Li 1.4 Al 0.4 Ti 1.4 Ge 0.2 (PO 4) 3 and Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , respectively. These solid electrolytes are unstable in water, but stable in saturated LiOH with saturated LiCl aqueous solution. The former solid electrolyte is unstable in contact with lithium metal, while the latter electrolyte shows stability against lithium metal.

Physica Status Solidi A-applications and Materials Science, 2011

All-solid-state batteries (SSBs) are attracting widespread attention as next-generation energy storage devices, potentially offering increased power and energy densities and better safety than liquid electrolyte-based Li-ion batteries. Significant research efforts are currently underway to develop stable and high-performance bulk-type SSB cells by optimizing the cathode microstructure and composition, among others. Electronically conductive additives in the positive electrode may have a positive or negative impact on cyclability. Herein, it is shown that for high-loading (pelletized) SSB cells using both a size-and surface-tailored Ni-rich layered oxide cathode material and a lithium thiophosphate solid electrolyte, the cycling performance is best when low-surface-area carbon black is introduced. Materials and methods Materials Small particle size NCM622 [Li 1+x (Ni 0.6 Co 0.2 Mn 0.2) 1Àx O 2 ] (d 50 ¼ 2.9 mm, d 90 ¼ 6.0 mm) was supplied by BASF SE. 10,17 Prior to use, a 1 wt% LiNbO 3 coating was applied to the cathode material. 4,5 Super C65 carbon black (Timcal), Ketjenblack EC-600JD (Akzo-Nobel), conical carbon nanobers (100 nm  20-200 mm; Sigma

In order to address power and energy demands of mobile electronics and electric cars, Li-ion technology is urgently being optimized by using alternative materials. This article presents a review of our recent progress dedicated to the anode and cathode materials that have the potential to fulfil the crucial factors of cost, safety, lifetime, durability, power density, and energy density. Nanostructured inorganic compounds have been extensively investigated. Size effects revealed in the storage of lithium through micropores (hard carbon spheres), alloys (Si, SnSb), and conversion reactions (Cr 2 O 3 , MnO) are studied. The formation of nano/micro core-shell, dispersed composite, and surface pinning structures can improve their cycling performance. Surface coating on LiCoO 2 and LiMn 2 O 4 was found to be an effective way to enhance their thermal and chemical stability and the mechanisms are discussed. Theoretical simulations and experiments on LiFePO 4 reveal that alkali metal ions and nitrogen doping into the LiFePO 4 lattice are possible approaches to increase its electronic conductivity and does not block transport of lithium ion along the 1D channel.