Electrolyte With Functionalized Boron Nitride Nanosheets for Dendrite‐Free Lithium Metal Anodes

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Lithium metal batteries (LMBs) are regarded as promising candidates for the next‐generation high‐energy‐density storage systems due to their unparalleled theoretical energy density and low redox potential. However, the commercialization of LMBs is tremendously plagued by the barbaric growth of lithium dendrite and the intricate decomposition of electrolytes. Herein, the tailored boron nitride nanosheets (BNNSs) with hydroxyl (BNNSs‐OH) and amidogen (BNNSs‐NH 2 ) functional groups are used as electrolyte additives to improve ion transport of the electrolyte and interface compatibility with lithium metal anode (LMAs). The BNNSs‐NH 2 ‐based electrolyte exhibits superior Li + deposition behavior due to the stronger electrostatic interaction between ‐NH 2 groups and TFSI − anions, and the modified electrolyte shows obvious advantages in balancing Li + concentration gradients and enhancing the lithium‐ion transference number. Therefore, the lithium‐ion transference number of the BNNSs‐NH 2 ‐based LMBs increases to 0.61. The Li||BNNSs‐NH 2 ||Li symmetric cell cycles stably over 1200 h at a current density of 0.5 mA cm −2 , and the average Coulombic efficiency of the Li||BNNSs‐NH 2 ||Cu asymmetric cell reaches up to 97.01% after 300 cycles at 0.5 mA cm −2 . In addition, the specific capacity of the LiFePO 4 ||BNNSs‐NH 2 ||Li full cell is 120.26 mAh g −1 after 600 cycles at 3C, corresponding to the capacity retention of 96.34%. This work provides a new strategy for homogenizing the ion deposition and enhancing the Li + transport through the tailored electrolyte additives, laying a theoretical foundation for the practical application of lithium metal batteries with high‐energy‐density.