A black phosphorus-graphite hybrid as a Li-ion regulator enabling stable lithium deposition

Abstract

Lithium (Li) metal anodes have been regarded as the most promising candidates for high energy density secondary lithium batteries due to their high specific capacity and low redox potential. However, the issues of Li dendrites caused by nonuniform lithium deposition during battery cycling severely hinder the practical applications of Li metal anodes. Herein, a hybrid of black phosphorus-graphite (BP-G) is introduced to serve as an artificial protective layer for the Li metal anode. The two-dimensional few-layer BP, which is lithophilic, combined with the high electronic conductive graphite can act as a regulator to adjust the migration of Li ions, delivering a uniform and stable lithium deposition. As the growth of lithium dendrites is inhibited, the utilization of Li metal achieves > 98.5% for over 500 cycles in Li||Cu half cells, and the life span is maintained over 2000 h in Li||Li symmetric cells with a low voltage hysteresis of 50 mV. Moreover, the LiFePO<sub>4</sub>||Li full cell with a BP-G Li-ion regulator presents significantly better specific capacity and cycling stability than that with the bare Li metal anode. Therefore, the introduction of the BP-G Li-ion regulator is demonstrated to be an effective approach to enable stable lithium deposition for rechargeable Li metal batteries.