Efficient trapping of lithium-ions by branched amine for stable lithium metal anodes

Abstract

Lithium metal batteries (LMBs) have attracted wide attention as high-energy–density energy storage devices, but their practical applications are hindered due to capacity degradation and safety concerns arising from the growth of lithium (Li) dendrites. The interaction between the electrode and Li, encompassing both Li-ions and Li metal, display significant potential for solving Li-dendrite issues in LMBs. Here, a novel strategy is reported to thin hybrid coating (∼1.3 μm) comprising highly polar poly(vinylidene fluoride) (PVDF) and branched poly(ethyleneimine) (PEI) onto Cu foil, employed as a current collector for the Li metal anode. The branched PEI contains amine group side chains that effectively capture Li ions, thereby facilitating rapid Li-ion transfer kinetics. Moreover, the inclusion of PEI enhances the surface energy of the polymer coating, leading to a reduction in the nucleation radius of Li and the promotion of uniform Li deposition. When coupled with a LiFePO4 (LFP) cathode, the Li-E40V@Cu||LFP full cell demonstrates an impressive initial capacity of 141.8 mA h g−1, which remains at 118.1 mA h g−1 after 518 cycles at 1C (1C = 170 mA h g−1). This investigation presents a novel approach to alleviate the formation of dendrites on Li metal anodes.