Phase behavior tuning enable high-safety and crack-free Ni-rich layered cathode for lithium-ion battery

Ni-rich layered cathodes suffer from rapid performance failure and structure degradation due to their complicated phase behavior during cycling. We demonstrate here a high-safety and crack-free Ni-rich cathode by tuning its phase behavior, through substituting a small-dose of Nb, which can induce an artificial surface cation mixing layer owing both high Ni migration barrier and stabilized oxygen framework. The irreversible phase transformation propagation is turned off after Nb doping, and the two-phase reaction during H2-H3 phase transition process transforms to a quasi-monophase reaction with minimal lattice mismatch and avoided interstress concentration, thus achieving a Nb doped LiNi0.9Co0.1O2 with outstanding capacity retention, a hysteretic onset exothermic temperature at high state of charge, and indistinguishable microcrack after cycling.