Microcracking of Ni-rich layered oxide does not occur at single crystal primary particles even abused at 4.7 V.

There is a controversial issue based on the particle cracking of the Ni-rich layered oxide cathode materials whether it occurs at the primary particles or the grain boundary. Herein, we found that the microcracking of NMC811 does not occur at single crystalline primary particles even abused at a severe upper cell voltage of 4.7 V having a lot of gas evolution since the single-crystal NMC811 has superior mechanical stability. The capacity retentions determined at 1C rate and a 100% state of charge (SOC) are 80% and 50% after 1000 cycles for single crystal and polycrystal NMC811, respectively.