Strain-retardant coherent perovskite phase stabilized Ni-rich cathode

Abstract

The use of state-of-the-art Ni-rich layered oxides (LiNi_xCo_yMn_1-x-yO₂, x > 0.5) as the cathode material for lithium-ion batteries can push the energy and power density to a higher level than is currently available^1,2. However, volume variation associated with anisotropic lattice strain and stress that is being developed during lithium (de)intercalation induces severe structural instability and electrochemical decay of the cathode materials, which is amplified further when the battery is operating at a high voltage (above 4.5 V), which is essential for unlocking its high energy^3-6. Even after much effort by the research community, an intrinsic strain-retardant method for directly alleviating the continuous accumulation of lattice strain remains elusive. Here, by introducing a coherent perovskite phase into the layered structure functioning as a 'rivet', we significantly mitigate the pernicious structural evolutions by a pinning effect. The lattice strain evolution in every single cycle is markedly reduced by nearly 70% when compared with conventional materials, which significantly enhances morphological integrity leading to a notable improvement in battery cyclability. This strain-retardant approach broadens the perspective for lattice engineering to release the strain raised from lithium (de)intercalation and paves the way for the development of high-energy-density cathodes with long durability.