The correlation between particle hardness and cycle performance of layered cathode materials for lithium-ion batteries.

The mechanical properties of cathode materials are among the critical factors that directly affect the lifespan of lithium-ion batteries (LIBs). However, a significant challenge remains in understanding the exact mechanism of mechanical degradation of present cathode materials that results in significant loss of performance during long-term operation. Herein, a comparative study on the correlation between mechanical strength (e.g. particle hardness) and cycle performance of the cathode materials (particularly those with layered structures) is presented. By improving the particle hardness of cathode materials via Mg doping, the formation of undesirable microcracks within the particles during cycling can be effectively suppressed, thus improving cycle performance. Structural and electrochemical analyses are performed in order to further elucidate the mechanical degradation mechanism of LIBs during repeat cycles, and identify a possible approach to the enhancement of electrochemical performance and long-term durability in present cathode materials. Image 1 • A strategy for improving the cycle performance of NCM cathode is presented. • The particle hardness of NCM can be effectively enhanced by Mg doping. • The enhanced particle hardness of Mg-NCM positively affects the cycle performance. • The formation of microcracks within Mg-NCM can be suppressed during cycles. [ABSTRACT FROM AUTHOR]