Enhanced cycling stability of single-crystal LiNi_0.83Co_0.07Mn_0.10O₂ by Li-reactive coating with H₃BO₃

Ni-rich cathode materials will be primarily used as next-generation high-specific energy cathode materials in lithium-ion batteries. However, residual Li formation and cracking considerably restrict the wide application of these materials. To address the issues related to cracking, micro-sized single-crystal cathode materials without internal grain boundaries are proposed. In this study, we constructed a thin LiBO2 layer on the single-crystal LiNi0.83Co0.07Mn0.10O2 particles by solvent-free H3BO3 modification. The residual Li on the material surface decreased by 14% through the reaction of LiOH/Li2CO3 and H3BO3. The coated materials exhibited higher initial Coulombic efficiency (88.44%), higher reversible capacity (213.4 mAh center dot g(-1) at 0.1C), and better cycling performance (91.31% retention over 50 cycles within 3.0-4.3 V at 1.0C) than the unmodified materials. Using the galvanostatic intermittent titration technique, electrochemical impedance spectroscopy (EIS), and inductively coupled plasma-optical emission spectroscopy (ICP-OES), we reveal the mechanism by which the electrochemical properties are improved upon H3BO3 modification. The superior electrochemical performances are associated with increased Li+ conductivity, lower charge transfer impedance, and suppressed transition metal dissolution. Therefore, this study demonstrates the importance of surface modification in obtaining Ni-rich single-crystal materials with enhanced performance.