Building Negative-Thermal-Expansion Protective Layers on the Grain Boundary of Ni-rich Cathodes Enables Safe and Durable High Voltage Lithium-Ion Batteries.

Ni-rich layered oxide cathode materials demonstrate high energy densities for Li-ion batteries, but the electrochemically driven thermal runaway and mechanical degradation remain their long-standing challenges in practical applications. Herein, it presents a novel ZrV O  (ZVO) coating with negative thermal expansion properties along the secondary particles and primary particle grain boundaries (GBs), to simultaneously enhance the structural and thermal stability of LiNi Co Mn O (NCM811). It unveils that, such an architecture can significantly enhance the electronic conductivity, suppress the microcracks of GBs, alleviate the layered to spinel/rock-salt phase transformation, and meanwhile relieve the lattice oxygen loss by increasing the oxygen vacancy formation energy increased (1.43 vs 1.90 eV). Consequently, the ZVO-coated NCM811 material demonstrates a remarkable cyclability with 86.5% capacity retention after 100 cycles, and an outstanding rate performance of 30 C under a high-voltage of 4.6 V, outperforming the state-of-the-art literature. More importantly, the Li transportation can be readily blocked at 120 °C by the negative-thermal-expansion ZVO coating, thus avoiding the high-temperature thermal runaway.