Engineering of cobalt-free Ni-rich cathode material by dual-element modification to enable 4.5 V-class high-energy-density lithium-ion batteries

Abstract

Ni-rich Co-free cathodes have attracted extensive attention for high-energy–density lithium ion batteries (LIBs). However, structural and interfacial instability in these cathodes accelerates capacity degradation under high-voltage operation. Herein, Ni-rich Co-free In/Sn dual-element modified cathode (InSn-LiNi0.85Mn0.09Al0.06O2, InSn-NMA85) was synthesized through a one-step sintering strategy. Dual-element doping along with the in-situ induced LiInO2 interphase synergistically prolongs the cycle life of the Ni-rich Co-free cathode under high voltage (≥4.5 V) as well as high temperature (≥45 °C). Comprehensive characterizations combined with DFT calculation confirm that In/Sn dual-element modification effectively increases Li+/Ni2+ mixing energy and oxygen release energy, stabilizes the lattice structure, and improves the electrochemical performance. Meanwhile, in-situ formed coating of LiInO2 effectively protects the cathode from redundant cathode-electrolyte side reactions, preserves the layered phase, and further inhibits the generation of microcracks after cycles. The modified cathode maintains superior capacity retention of ∼ 100 % and ∼ 90 % within the voltage range of 2.7–4.5 V at 30 °C and 45 °C, respectively, after 100 cycles. The modification strategy enables the Ni-rich Co-free layered NMA85 cathode to deliver comparable battery performance with NCM and NCA cathodes, which provides promising approaches for the application of Ni-rich Co-free cathode in 4.5 V-class high-energy–density LIBs.