A locally solvent-tethered polymer electrolyte for long-life lithium metal batteries

YF Zhu and ZJ Lao and MT Zhang and TZ Hou and X Xiao and ZH Piao and GX Lu and ZY Han and RH Gao and L Nie and XR Wu and YZ Song and CY Ji and J Wang and GM Zhou, NATURE COMMUNICATIONS, 15, 3914 (2024).

DOI: 10.1038/s41467-024-48078-7

Solid polymer electrolytes exhibit enhanced Li+ conductivity when plasticized with highly dielectric solvents such as N,N-dimethylformamide (DMF). However, the application of DMF-containing electrolytes in solid-state batteries is hindered by poor cycle life caused by continuous DMF degradation at the anode surface and the resulting unstable solid-electrolyte interphase. Here we report a composite polymer electrolyte with a rationally designed Hofmann-DMF coordination complex to address this issue. DMF is engineered on Hofmann frameworks as tethered ligands to construct a locally DMF-rich interface which promotes Li+ conduction through a ligand-assisted transport mechanism. A high ionic conductivity of 6.5 x 10-4 S cm-1 is achieved at room temperature. We demonstrate that the composite electrolyte effectively reduces the free shuttling and subsequent decomposition of DMF. The locally solvent-tethered electrolyte cycles stably for over 6000 h at 0.1 mA cm-2 in Li | |Li symmetric cell. When paired with sulfurized polyacrylonitrile cathodes, the full cell exhibits a prolonged cycle life of 1000 cycles at 1 C. This work will facilitate the development of practical polymer-based electrolytes with high ionic conductivity and long cycle life. Solid polymer electrolytes containing N,N-dimethylformamide (DMF) exhibit improved Li+ conductivity but poor cycle life due to incompatibility between the Li metal anode and DMF. Here, the authors report a polymer electrolyte composited with Hofmann- DMF complex that achieves both high Li+ conductivity and long cycle life.

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