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

Interface Engineering of All-Solid-State Batteries Based on Inorganic Solid Electrolytes

All-solid-state batteries (ASSBs) based on inorganic solid electrolytes (SEs) are one of the most promising strategies for next-generation energy storage systems and electronic devices due to the higher energy density and intrinsic safety. However, the poor solid-solid contact and restricted chemical/electrochemical stability of inorganic SEs both in cathode and anode SE interfaces cause contact failure and the degeneration of SEs during prolonged charge-discharge processes. As a result, the increasing interface resistance significantly affects the coulombic efficiency and cycling performance of ASSBs. Herein, we present a fundamental understanding of physical contact and chemical/electrochemical features of ASSB interfaces based on mainstream inorganic SEs and summarize the recent work on interface modification. SE doping, optimizing morphology, introducing interlayer/coating layer, and utilizing compatible electrode materials are the key methods to prevent side reactions, which are discussed separately in cathode/anode-SE interface. We also highlight the constant extra stack pressure applied during ASSB cycling, which is important to the electrochemical performance. Finally, our perspectives on interface modification for practical high-performance ASSBs are put forward.

Insights into interfacial chemistry of Ni-rich cathodes and sulphide-based electrolytes in all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLBs) have attracted increasing attention recently because they are more safe and have higher energy densities than conventional lithium-ion batteries. In particular, ASSLBs composed of Ni-rich cathodes, sulphide-based solid-state electrolytes (SSEs) and lithium metal anodes have been regarded as the most competitive candidates. Ni-rich cathodes possess high operating potential, high specific energy and low cost, and sulphide-based SSEs have excellent ionic conductivity comparable to that of liquid electrolytes. However, severe parasitic reactions and chemo-mechanical issues hinder their practical application. Herein, the structure, ionic conductivity, chemical or electrochemical stability and mechanical property of sulphide-based SSEs are introduced. Critical interfacial problems between Ni-rich cathodes and sulphide-based SSEs, including chemical or electrochemical parasitic reactions, space charge layer effect, mechanical stress and contact loss, are summarised. The corresponding solutions including coating layer construction and structure design are expounded. Finally, the remaining challenges are discussed, and perspectives are outlined to provide guidelines for the future development of ASSLBs.

Effect of a self-assembling La2(Ni0.5Li0.5)O4 and amorphous garnet-type solid electrolyte composite on a layered cathode material in all-solid-state batteries

In this article, we report the effect of a Li6_.75La₃Zr₂Al_0.25O₁₂ (LLZAO) composite Li(Ni_0.8Co_0.1Mn_0.1)O₂ (NCM811) cathode material on the performance of all-solid-state batteries (ASSBs) with oxide-based organic/inorganic hybrid solid electrolytes. The layered structure of Ni-rich cathode material Li(Ni _x Co_(1-x)/2Mn_(1-x)/2)O₂ (x > 0.6) (NCM) exhibiting a high specific capacity is among the suitable cathode materials for next-generation energy storage systems, particularly electric vehicles and portable devices for all-solid-state batteries. However, the ASSBs present a problem-the resistance at the interface between a cathode and solid electrolyte is larger than that with a liquid electrolyte because of point contact. To solve this problem, using a simultaneous co-precipitation method, we composited various amounts of LLZAO material and an ion conducting material on the cathode material's surface. Therefore, to optimize the value of the LLZAO material in the composite cathode material, the structure, cycling stability, and rate performance of the NCM-LLZAO composite cathode material in ASSBs with oxide-based inorganic/organic-hybrid electrolytes were investigated using powder X-ray diffraction analysis, field-emission scanning electron microscopy, electrochemical impedance spectroscopy, and galvanostatic measurements.

Constructing a High-Energy and Durable Single-Crystal NCM811 Cathode for All-Solid-State Batteries by a Surface Engineering Strategy

Single-crystal LiNi_0.8Co_0.1Mn_0.1O₂ (S-NCM811) with an electrochemomechanically compliant microstructure has attracted great attention in all-solid-state batteries (ASSBs) for its superior electrochemical performance compared to the polycrystalline counterpart. However, the undesired side reactions on the cathode/solid-state electrolyte (SSE) interface causes inferior capacity and rate capability than lithium-ion batteries, limiting the practical application of S-NCM811 in the ASSB technology. Herein, it shows that S-NCM811 delivers a high capacity (205 mAh g^-1, 0.1C) with outstanding rate capability (175 mAh g^-1 at 0.3C and 116 mAh g^-1 at 1C) in ASSBs by the coating of a nano-lithium niobium oxide (LNO) layer via the atomic layer deposition technique combined with optimized post-annealing treatment. The working mechanism is verified as the nano-LNO layer effectively suppresses the decomposition of sulfide SSE and stabilizes the cathode/SSE interface. The post-annealing of the LNO layer at 400 °C improves the coating uniformity, eliminates the residual lithium salts, and leads to small impedance increasing and less electrochemical polarization during cycling compared with pristine materials. This work highlights the critical role of the post-annealed nano-LNO layer in the applications of a high-nickel cathode and offers some new insights into the designing of high-performance cathode materials for ASSBs.