Raising the Intrinsic Safety of Layered Oxide Cathodes by Surface Re-Lithiation with LLZTO Garnet-Type Solid Electrolytes.

Wang, Junyang; Chen, Rusong; Yang, Lufeng; Zan, Mingwei; Chen, Penghao; Li, Yu; Li, Wenjun; Yu, Huigen et al. · Adv Mater · 2022

basic_science · Level V

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Abstract

Battery safety concerns are becoming more and more prominent with the increasing demands of lithium-ion batteries (LIBs) with higher energy density. The greatest threat to battery safety derives from the easy release of oxygen from the high-capacity layered oxide cathodes at highly delithiated states and subsequent exothermic reactions with reductive agents in batteries. Herein, it is demonstrated that solid electrolyte Li<sub>6.5</sub> La<sub>3</sub> Zr<sub>1.5</sub> Ta<sub>0.5</sub> O<sub>12</sub> (LLZTO) can supply lithium ions to re-lithiate the charged LiCoO<sub>2</sub> at elevated temperatures. Such a re-lithiation process can lower the state-of-charge of LiCoO<sub>2</sub> , and thus, inherently postpones its structural decomposition and the associated release of oxygen during the heating process. The LiCoO<sub>2</sub> /graphite full cell with 1 wt% addition of LLZTO demonstrates remarkably enhanced safety performances. This work proposes a strategy that through the adoption of solid electrolytes to solve safety issues raised from both flammable liquid electrolytes and high capacity cathodes, to achieve intrinsically safe LIBs or solid-state batteries.