Enhanced microstructure stability of LiNi_0.8Co_0.1Mn_0.1O₂ cathode with negative thermal expansion shell for long-life...

With high specific energy density, Ni-rich layered LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) material has become one promising cathode candidate for advanced lithium-ion batteries (LIBs). However, severe capacity fading induced by microstructure degradation and deteriorated interfacial Li⁺ transportation upon repeated cycling makes the commercial application of NCM cathode in dilemma. To address these issues, LiAlSiO₄ (LASO), one unique negative thermal expansion (NTE) composite with high ionic conductivity, is utilized as a coating layer to improve the electrochemical performances of NCM material. Various characterizations demonstrate that LASO modification can endow NCM cathode with significantly enhanced long-term cyclability, through reinforcing the reversibility of phase transition and restraining lattice expansion, as well as depressing microcrack generation during repeated delithiation-lithiation processes. The electrochemical results indicate that LASO-modified NCM cathode can deliver an excellent rate capability of 136 mAh g^-1 at a high current rate of 10 C (1800 mA g^-1), larger than that of the pristine cathode (118 mAh g^-1), especially higher capacity retention of 85.4% concerning the pristine NCM cathode (65.7%) over 500 cycles under 0.2 C. This work provides a feasible strategy to ameliorate the interfacial Li⁺ diffusion and suppress the microstructure degradation of NCM material during long-term cycling, which can effectively promote the practical application of Ni-rich cathode in high-performance LIBs.