Enabling stable interface by constructing asymmetric organic-inorganic bi-functional composite electrolyte of high-voltage lithium metal batteries

Solid-state lithium metal batteries (SSLMBs) are considered to be the next generation of high safety and high energy density storage device. However, the accidental lithium dendrites growth and the solid-solid contact problem have seriously hindered the development of their commercialization. Therefore, it is of great significance to develop high-modulus electrolytes to suppress lithium dendrites growth and achieve close-knit contact between electrolyte/electrodes. Herein, we utilize the natural settlement of Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) during in-situ polymerization method of polyester-based trimethylolpropane trimethacrylate (TMPTMA) and 1,6-hexanediol diacrylate (HDDA) monomer and the based on the selective adsorption of glass fiber to construct an asymmetric bi-functional composite electrolyte membrane (A-P(PF) 1 TH-X%LLZTO). To match the high voltage cathode material, the polymer electrolyte matrix containing ploy (vinyl carbonate) (PVC)/lithium difluoro(oxalato) borate (LiDFOB) was introduced into the pore of the cathode material to construct stable cathode electrolyte interphase (CEI) layer on the surface of the active material. The characterization of Li solid NMR spectra shows that the ceramic oxides provide effective pathways for the Li + conduction between the asymmetric electrolyte and the lithium anode. Symmetric Li Li cells exhibit low charge voltage polarization, can operate stably at 0.2 mA cm −2 for over 700 h, and can increase the critical current density to 2.1 mA cm −2 . The lithium metal batteries (LMBs) assembled with high voltage LiCoO 2 cathode has the capacity retention rate of 99.62 % after 500 cycles (remained 118.08 mAh g −1 at 1C). Such excellent electrochemical properties are attributed to the establishment of asymmetric electrolytes that can form inorganic component-rich SEI layer on the side of Li metal. This work demonstrates an effective interface engineering strategy that can simultaneously realize the interface stability of the cathode and anode electrode/solid electrolyte, which shows great potential for promoting the development of LMBs.