Solid‐State Li–Metal Batteries: Challenges and Horizons of Oxide and Sulfide Solid Electrolytes and Their Interfaces

Abstract

lightweight, and compact and allow for versatile device geometries. They must also be scalable and offer high energy density to provide improved packing efficiency and longer device operation. Although both Ni-MH batteries and LIBs have been commercialized since the 1990s, [1] LIBs possess twice the gravimetric/volumetric energy density (250 Wh kg −1 /700 Wh L −1 vs 170 Wh kg −1 /350 Wh L −1 ), [2] higher battery voltage (3.7 V vs 1.2 V), and longer cycle life with lower self-discharge, [3] contributing tremendously to the proliferation of portable electronic devices (e.g., mobile phones, laptops, cameras, tablets) as well as emerging new technologies such as wearable electronic devices (e.g., smart watches and sport-related tracking devices). Their high gravimetric/ volumetric energy density, [2] excellent cycle life (thousands of cycles), and lack of the memory effect have positioned LIBs as state-of-the-art power sources and one of the greatest successes of modern electrochemistry, revolutionizing the way we acquire, process, transmit, and share information globally. Nevertheless, advances in battery energy density, safety, costs, and flexibility in shape and size are still needed to keep up with the rapidly growing demand for devices with even longer runtime as well as real-time data collection and transmission capabilities in addition to increasingly energy-demanding applications such as electric vehicles (EVs) and electricity grid storage. Even though LIBs were first commercialized in all electric vehicles (EVs) in 2010 and also emerged for grid application in the same time frame, the low energy density (≈250 Wh kg −1 ) and high average cost (≈$156 kWh −1 in 2019) of conventional LIBs do not meet the requirements for advanced EVs and grid-scale energy storage. [4][5][6] Specifically, the driving range per charge (miles), which is related to the energy density of each cell, and the cost are important parameters for EVs. For example, one 85 kWh battery pack in a Tesla Model S requires 7104 LIB cells, with an energy density of 265 Wh kg −1 , providing an average range of 250 miles, which is ahead of the range of other EVs but still behind the target of 375 miles. [4] In grid-scale applications, LIBs can be used for various tasks: frequency regulation, peak shaving, load leveling, and large-scale integration of renewable energies, with specific properties generally required for each task. For frequency regulation, LIBs need to provide a fast response, high rate performance, and high-power capability,The introduction of new, safe, and reliable solid-electrolyte chemistries and technologies can potentially overcome the challenges facing their liquid counterparts while widening the breadth of possible applications. Through tech-historic evolution and rationally analyzing the transition from liquidbased Li-ion batteries (LIBs) to all-solid-state Li-metal batteries (ASSLBs), a roadmap for the development of a successful oxide and sulfide-based ASSLB focusing on interfacial challenges is introduced, while accounting ...

Li6SiO4Cl2: A Hexagonal Argyrodite Based on Antiperovskite Layer Stacking

“…This is distinct from the cubic oxide argyrodite, Li 6 PO 5 Br, in which lithium remains localized on the trigonal planar 24 g Wyckoff position in the F 4̅3 m structure over a wide (173–873 K) temperature range ( Figure 1 e). 48 Stabilization of this lithium disorder, which enables access to higher-energy sites in Li 6 SiO 4 Cl 2 , would increase lithium-ion migration compared against the room-temperature structure.…”

Effect of surface carbonates on the cyclability of LiNbO3-coated NCM622 in all-solid-state batteries with lithium thiophosphate electrolytes

“…At the positive electrode side, Ni-rich layered lithium metal oxides, such as LiNi 1-x-y Co x Mn y O 2 (NCM or NMC) or LiNi 1-x-z Co x Al z O 2 (NCA) with ≥ 0.6 Ni content, are regarded generally as state-of-the-art cathode materials for bulk solid-state battery (SSB) applications [18][19][20][21] , as in the case of energy-dense LIBs. However, combining such cathode materials with lithium thiophosphate solid electrolytes is hampered by side reactions at the interfaces during electrochemical cycling, leading to low reversibility and impedance buildup and therefore to performance decay [22][23][24][25][26][27] . Hence, in order to achieve stable cycling of the cathode, the outer surface of the storage particles needs to be covered by a protective layer [28][29][30] , with Li-based oxides being the most widely studied coating materials (e.g., LiNbO 3 31 , LiTaO 3 32 , Li 2 ZrO 3 33 , Li 4 Ti 5 O 12 34 or Li 2 CO 3 35 ).…”

Widening the Range of Trackable Environmental and Health Pollutants for Li‐Garnet‐Based Sensors

“…For instance, the Li-garnet Li 7 La 3 Zr 2 O 12 (LLZO) is considered one of the promising solid electrolytes to be integrated in Li-metal-based SSBs considering its high room-temperature ionic conductivity (≈mS cm −1 for the cubic phase), high chemical stability toward Li metal (reduction potential of 0.05 V vs Li + /Li), and wide electrochemical stability window. [55,56] Hence, it is not surprising that with the discovery of fast Li-garnet conductors as solid electrolytes for batteries, the idea for their integration in sensors to accelerate tracking of CO 2 soon followed. [57,58] Moreover, prior theoretical and experimental studies of LLZO stability toward humidity and CO 2 exposure [59,60] [58] The sensors offered a fast response time of <60 s at the lowered operation temperature of ≈320 °C, tracking 400-4000 ppm levels of CO 2 .…”