Locally regulating Li+ distribution on an electrode surface with Li–Sn alloying nanoparticles for stable lithium metal anodes

Despite the fact that lithium metal batteries (LMBs) have the advantage of higher energy density than traditional lithium-ion batteries (LIBs), the development of Li anodes is hindered by the issues of dendritic Li growth and parasitic reactions during cycling, which can cause a coulombic efficiency decrease and capacity decay. Herein, a Li-Sn composite anode is developed by a facile rolling method. The in situ generated Li22Sn5 nanoparticles are uniformly distributed in the Li-Sn anode after the rolling process. The Li22Sn5 nanoparticles on the surface of the electrode exhibit excellent lithiophilicity, reducing the Li nucleation barrier. Multiphysics phase simulation discloses the distribution of local current density around the holes, guiding Li preferentially to deposit back onto the sites of previous Li stripping, and then realizing a controllable plating/stripping behavior of Li on the Li-Sn composite anode. Consequently, the symmetrical cell of Li-Sn||Li-Sn achieves a stable cycling lifetime of more than 1200 h at a current density of 1 mA cm-2 with a fixed capacity of 1 mA h cm-2. Besides, the full cell pairing with the LiFePO4 cathode delivers excellent rate performance and capacity retention after long cycles. This work provides new insight to modify the Li metal for preparing dendrite-free anodes.