Solid electrolytes with desirable properties such as high ionic conductivity,wide electrochemical stable window,and suitable mechanical strength,and stable electrode-electrolyte interfaces on both cathode and anode side are essential for high-voltage all-solid-state lithium batteries (ASSLBs) to achieve excel-lent cycle stability.In this work,a novel strategy of using LiF and LiNO3 as synergistic additives to boost the performance of PEO-PVDF/LLZTO-based composite solid electrolytes (CSEs) is developed,which also promotes the assembled high-voltage ASSLBs with dual-interfaces stability characteristic.Specifically,LiF as an inactive additive can increase the electrochemical stability of the CSE under high cut-off voltage,and improve the high-voltage compatibility between cathode and CSE,thus leading to a stable cath-ode/CSE interface.LiNO3 as an active additive can lead to an enhanced ionic conductivity of CSE due to the increased free-mobile Li+ and ensure a stable CSE/Li interface by forming stable solid electrolyte inter-phase (SEI) on Li anode surface.Benefiting from the improved performance of CSE and stable dual-interfaces,the assembled NCM622/9[PEO15-LiTFSI]-PVDF-15LLZTO-2LiF-3LiNO3/Li cell delivers a high rate capacity of 102.1 mAh g-1 at 1.0 C and a high capacity retention of 77.4％ after 200 cycles at 0.5 C,which are much higher than those of the ASSLB assembled with additive-free CSE,with only 60.0 mAh g-1 and 52.0％,respectively.Furthermore,novel cycle test modes of resting for 5 h at different charge states after every 5 cycles are designed to investigate the high-voltage compatibility between cathode and CSE,and the results suggest that LiF additive can actually improve the high-voltage compat-ibility of cathode and CSE.All the obtained results confirm that the strategy of using synergistic additives in CSE is an effective way to achieve high-voltage ASSLBs with dual-interfaces stability.

Liansheng Li;Yuanfu Deng;Huanhuan Duan;Yunxian Qian;Guohua Chen

The Key Laboratory of Fuel Cell for Guangdong Province,School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China;Electrochemical Energy Engineering Research Center of Guangdong Province,South China University of Technology,Guangzhou 510640,Guangdong,China;Shenzhen CAPCHEM Technol Co Ltd.,Shenzhen 518118,Guangdong,China;Department of Mechanical Engineering,The Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong,China

能源化学

[1]Liansheng Li;Yuanfu Deng;Huanhuan Duan;Yunxian Qian;Guohua Chen-.LiF and LiNO3 as synergistic additives for PEO-PVDF/LLZTO-based composite electrolyte towards high-voltage lithium batteries with dual-interfaces stability)[J].能源化学,2022(02):319-328

CSEs,PEO15,15LLZTO,2LiF,3LiNO3,ASSLB,compat

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