Mitigating internal strain of nickel-rich layered oxide enabled by microstructure modification

Abstract

Nickel-rich layered oxide, as the most promising cathode material for lithium-ion batteries (LIBs), possesses high energy density. Nonetheless, the formation of microcracks as well as the release of lattice oxygen during electrochemical cycling are the main issues facing nickel-rich layered oxide. In this work, by introducing high-valent antimony (Sb) elements into LiNi_0.9Co_0.05Mn_0.05O₂ (NCM) during the lithiation process of Ni_0.9Co_0.05Mn_0.05(OH)₂ hydroxide precursor, the crystal surface energy during particle growth is significantly reduced, regulating the synthesized primary particles with radial alignment. Such a structure could mitigate the accumulation of strain due to the anisotropic lattice expansion and contraction induced by the phase transition during the lithium extraction/insertion process, thus effectively suppressing the generation of microcracks. Meanwhile, the introduction of strong antimony-oxygen covalent bonds into the lattice of the material can restrain the releasing of lattice oxygen and mitigate the structural collapse. Therefore, the 0.5mol% antimony-doped NCM (0.5 S b-NCM) exhibits excellent electrochemical performance, delivering a high initial discharge capacity up to 219.8 mA h/g at 0.1 C, and high capacity retention of 97.09 % over 200 cycles at 1 C. This work presents an effective way to regulate the microstructure to mitigate internal strain and oxygen evolution of nickel-rich cathode materials.