Microstrain Alleviation in High-Energy Ni-Rich ma NCMA Cathode for Long Battery Life

Abstract

A hybrid-structured Li[Ni0.9Co0.045Mn0.045Al0.01] (HS-NCMA90) cathode is proposed, in which Li[Ni0.92Co0.04Mn0.03Al0.01]O2 forms the interior of the cathode particle enclosed in a buffer layer of Li[Ni0.845Co0.067Mn0.078Al0.01]O2. The hybrid structure is compositionally partitioned into interior and outer regions and develops radially aligned, size-refined primary particles with a high aspect ratio. This optimized microstructure enables the primary particles to contract uniformly and produces differential states of stress that apply compressive stress to the particle interior, thereby effectively suppressing the propagation of microcracks toward the outer surface. The unique microstructure of the HS-NCMA90 cathode markedly improves its cycling stability, which retains 84.7% of its initial capacity after 1500 cycles. The proposed microstructurally engineered cathode, with high mechanical stability and fracture toughness, prolongs the service life of batteries with high energy densities.