北京大学夏定国团队提出了富锂阴极材料中抑制阴离子二聚化的金属配体自旋锁策略。相关研究成果于2025年1月1日发表在国际知名学术期刊《美国化学会杂志》。

阴离子二聚对富锂阴极材料（LCMs）在高能量密度锂离子电池中的应用提出了重大挑战，因为它具有有害影响，包括快速的容量和电压衰减、缓慢的反应动力学和较大的电压滞后。

该文中，研究人员提出了一种金属-配体自旋锁定策略来抑制阴离子二聚化，该策略涉及将具有反铁磁性超交换相互作用的Fe-Ni对引入LCM，以将阴离子中未配对电子的自旋方向锁定在同一方向。作为概念验证，研究人员将该策略应用于层内无序Li₂TiS₃（ID-LTS）以抑制S-S二聚化。

使用恒电流充电/放电和间歇滴定技术进行的电化学表征表明，掺入ID-LTS的Fe-Ni对的阴离子氧化还原活性显著增强，电压滞后降低，动力学得到改善。Fe L_2,3边X射线吸收光谱和磁化率测量表明，金属-配体自旋锁定效应和随之而来的阴离子二聚抑制，涉及S和Fe之间的配体到金属电荷转移。

对掺有富锂层状氧化物（Li_0.7Li_0.1Fe_0.2Ni_0.1Mn_0.6O₂）的Fe-Ni对的进一步电化学测试表明，π背键在增强配体到金属从S到Fe的电荷转移中的重要性。

研究结果表明了金属配体自旋锁定策略，在开发高性能LCMs中的潜在应用。

附：英文原文

Title: Metal–Ligand Spin-Lock Strategy for Inhibiting Anion Dimerization in Li-Rich Cathode Materials

Author: Zewen Jiang, Kun Zhang, Qihang Ding, Chuan Gao, Yuxuan Zuo, Hangchao Wang, Junfei Cai, Biao Li, Xinping Ai, Dingguo Xia

Issue&Volume: January 1, 2025

Abstract: Anion dimerization poses a significant challenge for the application of Li-rich cathode materials (LCMs) in high-energy-density Li-ion batteries because of its deleterious effects, including rapid capacity and voltage decay, sluggish reaction kinetics, and large voltage hysteresis. Herein, we propose a metal–ligand spin-lock strategy to inhibit anion dimerization, which involves introducing an Fe–Ni couple having antiferromagnetic superexchange interaction into the LCM to lock the spin orientations of the unpaired electrons in the anions in the same direction. As proof of concept, we applied this strategy to intralayer disordered Li2TiS3 (ID-LTS) to inhibit S–S dimerization. Electrochemical characterization using the galvanostatic charge/discharge and intermittent titration technique demonstrated the considerably enhanced anionic redox activity, reduced voltage hysteresis, and improved kinetics of the Fe–Ni-couple-incorporated ID-LTS. Fe L2,3-edge X-ray absorption spectroscopy and magnetic susceptibility measurements revealed that the metal–ligand spin-lock effect and consequent suppression of anion dimerization involve ligand-to-metal charge transfer between S and Fe. Further electrochemical tests on a Fe–Ni-couple-incorporated Li-rich layered oxide (Li0.7Li0.1Fe0.2Ni0.1Mn0.6O2) indicated the importance of the π backbond in enhancing ligand-to-metal charge transfer from S to Fe. These findings demonstrate the potential application of our metal–ligand spin-lock strategy in the development of high-performance LCMs.

DOI: 10.1021/jacs.4c10815

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c10815