Constructing a LiPON Layer on a 3D Lithium Metal Anode as an Artificial Solid Electrolyte Interphase with Long-Term Stability

Abstract

The problem of lithium dendrite growth has persistently hindered the advancement of lithium metal batteries. Lithium phosphorus oxynitride (LiPON), functioning as an amorphous solid electrolyte, is extensively employed as an artificial solid electrolyte interphase (SEI) owing to its remarkable stability and mechanical strength, which is beneficial for effectively mitigating dendrite growth. Nevertheless, the significant challenge arises from the volume changes in the Li metal anode during cycling, leading to the vulnerability of LiPON due to its high rigidity, which impedes the widespread use of LiPON. To address this problem, our study introduces a lithium-boron (Li-B) alloy as the anode, featuring a 3D structure, which can be synergistic with the artificial LiPON layer during cycling, leading to a better performance. The average Coulombic efficiency (CE) of a Li || Cu half-cell reaches 95% over 120 cycles. The symmetric cells exhibit sustained operation for 950 h with a low voltage polarization of less than 20 mV under a current density of 0.5 mA/cm2 and for 410 h under 1 mA/cm2.