Bottom-Up Li Deposition by Constructing a Multiporous Lithiophilic Gradient Layer on 3D Cu Foam for Stable Li Metal Anodes
Yang Lv, Qingxu Zhang, Chao Li, Chao Ma, Weiye Guan, Xizheng Liu, Yi Ding
Abstract
Metallic current collectors with three-dimensional (3D) porous structures have been considered as ideal hosts for Li metal anodes because of their ability to accommodate anode volume fluctuations and suppress Li dendrite formation. However, in a conductive 3D porous framework, Li preferentially deposits at the top surface, resulting in uneven deposition, and ultimately forms Li dendrites. Herein, we propose a deposition regulation strategy by fabricating a lithiophilic nanoporous CuSnAl layer at the bottom of a porous Cu foam to induce bottom-up and dense Li deposition. The as-prepared CuSnAl@Cu foam demonstrates enhanced Li deposition reversibility with a lifespan over 2000 h in symmetrical cells at 1 mA cm–2. Full cells coupled with lithiated CuSnAl@Cu foam and a LiFePO4 cathode exhibit outstanding electrochemical performance, with a Coulombic efficiency (CE) of 99.6% over 300 cycles, which is much better than that using a pure Cu foam or Cu foil. Moreover, the electric field distribution at the CuSnAl layer has been directly observed to disclose the intrinsic mechanism of bottom-up Li growth. This design of 3D metallic current collectors with a lithiophilicity gradient provides new insights into stable Li metal anodes, and thus, into Li metal batteries.