A highly conductive and electrochemically stable dual-salt solid polymer electrolyte (SPE) for high capacity cathode was developed. A phase-diagram approach was adopted to provide rational guidance for achieving a high ionic conductivity (over 1.76 mS/cm at 30 oC). The synergy of combining different salts rendered the SPE a superior electrochemical stability with an electrochemical window from 0 to 5 V (vs. Li+/Li) in linear sweep voltammetry and up to 4.15 V in lithium metal batteries (LMBs). The SPE exhibited outstanding long-term stability performance in lithium plating/striping experiments under current densities from 0.08 to 0.5 mA/cm2. The solid-state lithium metal batteries (with LiNi0.8Co0.15Al0.05O2, NCA, cathode) exhibited initial capacities of 165 mAh/g at 0.1 C rate and 113 mAh/g at 1 C rate at 30 oC. The average Coulombic efficiency of solid-state batteries was over 99.99% in the first 1000 cycles at 1 C rate and the capacity retention was 66% after 1000 cycles. In addition, the per cycle capacity fading after the initial 100 cycles was only 0.017 %/cycle. The results demonstrate that the SPE is a promising candidate electrolyte for high energy density solid-state lithium metal battery.

Superionic conductive polymer electrolyte for solid lithium-metal batteries with long cycle life

2019 Spring National Meeting

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