Rare earth-mediated synergistic lattice stabilization and interface protection for suppressed phase transition and superior electrochemical performance in Ni-rich cathodes

Abstract

Nickel-rich ternary layered oxides are mainstream cathode materials for high-performance lithium-ion batteries, but they face critical challenges (lattice oxygen release, Li⁺/Ni²⁺ cation mixing, microcrack propagation, and transition metal (TM) dissolution) during repeated charge–discharge cycles. Herein, we report a synergistic modification strategy for high-nickel oxides via spray-drying coupled with a high-temperature solid-state reaction, enabling simultaneous formation of a Sm-containing oxide coating and Sm³⁺ lattice doping. Structural characterization confirms uniform encapsulation by a thin Sm-based oxide layer, which suppresses TM dissolution and mitigates electrode–electrolyte side reactions. DFT calculations and experimental analyses verify that Sm³⁺ substitutes partial Ni²⁺ sites in the lattice. This dual modification enhances structural integrity and enlarges interlayer spacing via a “pillaring effect”, reducing the Li⁺ diffusion barrier. Electrochemically, the optimized Sm-modified cathode retains 94.5% of its initial capacity after 150 cycles at 1.0C (41.5% improvement over the unmodified sample) and exhibits excellent rate capability (153.49 mA h g⁻¹ at 10C). This work provides a promising avenue for the rational design of high-stability, high-rate nickel-rich cathodes for advanced lithium-ion batteries.