Thermodynamically Stable Dual-Modified LiF&FeF<sub>3</sub> layer Empowering Ni-Rich Cathodes with Superior Cyclabilities.

Chu, Youqi; Mu, Yongbiao; Zou, Lingfeng; Hu, Yan; Cheng, Jie; Wu, Buke; Han, Meisheng; Xi, Shibo et al. · Adv Mater · 2023

basic_science · Level V

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Abstract

Pushing the limit of cutoff potentials allows nickel-rich layered oxides to provide greater energy density and specific capacity whereas reducing thermodynamic and kinetic stability. Herein, a one-step dual-modified method is proposed for in situ synthesizing thermodynamically stable LiF&FeF<sub>3</sub> coating on LiNi<sub>0.8</sub> Co<sub>0.1</sub> Mn<sub>0.1</sub> O<sub>2</sub> surfaces by capturing lithium impurity on the surface to overcome the challenges suffered. The thermodynamically stabilized LiF&FeF<sub>3</sub> coating can effectively suppress the nanoscale structural degradation and the intergranular cracks. Meanwhile, the LiF&FeF<sub>3</sub> coating alleviates the outward migration of O<sup>α-</sup> (α<2), increases oxygen vacancy formation energies, and accelerates interfacial Li<sup>+</sup> diffusion. Benefited from these, the electrochemical performance of LiF&FeF<sub>3</sub> modified materials is improved (83.1% capacity retention after 1000 cycles at 1C), even under exertive operational conditions of elevated temperature (91.3% capacity retention after 150 cycles at 1C). This work demonstrates that the dual-modified strategy can simultaneously address the problems of interfacial instability and bulk structural degradation and represents significant progress in developing high-performance lithium-ion batteries (LIBs).