Mastering the interface for advanced all-solid-state lithium rechargeable batteries.

Li, Yutao; Zhou, Weidong; Chen, Xi; Lü, Xujie; Cui, Zhiming; Xin, Sen; Xue, Leigang; Jia, Quanxi et al. · Proc Natl Acad Sci U S A · 2016

basic_science · Level V

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Abstract

A solid electrolyte with a high Li-ion conductivity and a small interfacial resistance against a Li metal anode is a key component in all-solid-state Li metal batteries, but there is no ceramic oxide electrolyte available for this application except the thin-film Li-P oxynitride electrolyte; ceramic electrolytes are either easily reduced by Li metal or penetrated by Li dendrites in a short time. Here, we introduce a solid electrolyte LiZr<sub>2</sub>(PO4)<sub>3</sub> with rhombohedral structure at room temperature that has a bulk Li-ion conductivity σ<sub>Li</sub> = 2 × 10<sup>-4</sup> S⋅cm<sup>-1</sup> at 25 °C, a high electrochemical stability up to 5.5 V versus Li<sup>+</sup>/Li, and a small interfacial resistance for Li<sup>+</sup> transfer. It reacts with a metallic lithium anode to form a Li<sup>+</sup>-conducting passivation layer (solid-electrolyte interphase) containing Li<sub>3</sub>P and Li<sub>8</sub>ZrO<sub>6</sub> that is wet by the lithium anode and also wets the LiZr<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> electrolyte. An all-solid-state Li/LiFePO<sub>4</sub> cell with a polymer catholyte shows good cyclability and a long cycle life.