Regulating the Potential of Anion Redox to Reduce the Voltage Hysteresis of Li-Rich Cathode Materials

Yuxuan Zuo; Huaifang Shang; Jiazheng Hao; Jin Song; Fanghua Ning; Kun Zhang; Lunhua He; Dingguo Xia

doi:10.1021/jacs.2c11640

Regulating the Potential of Anion Redox to Reduce the Voltage Hysteresis of Li-Rich Cathode Materials

J Am Chem Soc. 2023 Mar 8;145(9):5174-5182. doi: 10.1021/jacs.2c11640. Epub 2023 Feb 9.

Authors

Yuxuan Zuo¹, Huaifang Shang², Jiazheng Hao³, Jin Song¹, Fanghua Ning¹, Kun Zhang¹, Lunhua He³, Dingguo Xia¹

Affiliations

¹ Beijing Key Laboratory of Theory and Technology for Advanced Batteries Materials, School of Materials Science and Engineering, Peking University, Beijing 100871, China.
² Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
³ Spallation Neutron Source Science Center, Dongguan 523803, China.

PMID: 36757130
DOI: 10.1021/jacs.2c11640

Abstract

Layered Li-rich oxides (LROs) that exhibit anionic and cationic redox are extensively studied due to their high energy storage capacities. However, voltage hysteresis, which reduces the energy conversion efficiency of the battery, is a critical limitation in the commercial application of LROs. Herein, using two Li₂RuO₃ (LRO) model materials with C2/c and P2₁/m symmetries, we explored the relationship between voltage hysteresis and the electronic structure of Li₂RuO₃ by neutron diffraction, in situ X-ray powder diffraction, X-ray absorption spectroscopy, macro magnetic study, and electron paramagnetic resonance (EPR) spectroscopy. The charge-transfer band gap of the LRO cathode material with isolated e_g electron filling decreases, reducing the oxidation potential of anion redox and thus displaying a reduced voltage hysteresis. We further synthesized Mn-based Li-rich cathode materials with practical significance and different electron spin states. Low-spin Li_1.15Ni_0.377Mn_0.473O₂ with isolated e_g electron filling exhibited a reduced voltage hysteresis and high energy conversion efficiency. We rationalized this finding via density functional theory calculations. This discovery should provide critical guidance in designing and preparing high-energy layered Li-rich cathode materials for use in next-generation high-energy-density Li-ion batteries based on anion redox activity.