Noninvasive rejuvenation strategy of nickel-rich layered positive electrode for Li-ion battery through magneto-electrochemical synergistic activation
Haochen Gong, Yu Cao, Baoshan Zhang, Jinsong Zhang, Yiming Zhang, Huili Wang, Shaojie Zhang, Xiaoyi Wang, Yue Mao, Shuo Liu, Chengyu Han, Qianxin Xiang, Chaoyi Zhou, Jie Sun
Abstract
Nickel-rich layered oxides are one of the most promising positive electrode active materials for high-energy Li-ion batteries. Unfortunately, the practical performance is inevitably circumscribed by the structural deterioration deriving from the Ni/Li antisite disorder, leading to severe capacity loss and life attenuation. Herein, we propose an economical and facile rejuvenation strategy by employing the magneto-electrochemical synergistic activation targeting the positive electrode in assembled Li-ion batteries. This approach induces a transition of Ni3+ from high-spin to low-spin, reducing the super-exchange interaction of Ni-O-transition metal (TM). Meanwhile, electrochemical reaction drives Li+ from the host material and promotes Ni3+ to reoccupy TM layer, recovering intrinsic Li site and extending cycle life. The strategy demonstrates that low-quality positive electrodes can be converted to high-quality ones. Notably, the method can revitalize an aged Li-ion pouch cell (SiC||NCM811, 8 Ah nominal capacity) via optimizing cation occupancy and increase its capacity by 10% from 6.49 to 7.14 Ah at 1 C, illustrating the benefits of the upcycling process. Severe Ni/Li antisite disorder in nickel-rich layered oxides leads to structural degradation and performance decay in Li-ion batteries. Here, authors report a noninvasive strategy of magnetoelectrochemical synergistic activation to realize ordered cation rearrangement and recovery battery capacity.