Enabling All-Solid-State Li Metal Batteries Operated at 30 ℃ by Molecular Regulation of Polymer Electrolyte

摘要

The low ionic conductivity of poly(ethylene oxide) (PEO)-based polymer electrolytesat room temperature and the undesired lithium-dendrite growth at LiPEOinterface impede their further application. Herein, a PEO polymer is regulatedat the molecular level through a copper ion (Cu~(2+)) coordination effect with bothPEO and Li salts to achieve a high Li+ conductivity of 0.2 mS cm?1 and a transferencenumber of 0.42 at 30 ℃. Moreover, the Cu-coordinated PEO electrolyteis neither sticky nor hygroscopic because the hydrophilic oxygen groups in PEOare terminated by Cu ions. Furthermore, the in situ formed F/Li-rich inorganiclayer induced by CuF_2 additive accelerates Li+ transport kinetics and enablesuniform Li+ deposition during Li plating/stripping. As a result, the Cu~（2+）-coordinatedPEO electrolytes deliver a high critical current density of 1.5 mA cm~（?2）at 30℃. An all-solid-state Li-LiNi_（0.83）Co_（0.12）Mn_（0.05）O_2 (NCM83) battery with sucha copper coordinated PEO electrolyte exhibits a long cycle life over 500 cycleswith a capacity retention of 71 under 0.6 C at 30℃. When the mass loadingincreases to a record high of 7 mg cm~（?2）, the Li-NCM83 cell delivers a high arealcapacity of 1.07 mAh cm~（?2） under 0.1 C at 30℃.