Enhancing Cycle Life of Graphite‖LiFePO₄ Batteries via Copper Substituted Li₂Ni_1-xCu_xO₂ Cathode Prelithiation Additive

Authors

Jianming Zheng, Xiamen Key Laboratory of Lithium Battery Energy Storage Application Materials and Safety; Xiamen Hithium Energy Storage Technology Co., Ltd, Xiamen, 361000, Fujian, China
Jingwen Zhang, Xiamen Key Laboratory of Lithium Battery Energy Storage Application Materials and Safety; Xiamen Hithium Energy Storage Technology Co., Ltd, Xiamen, 361000, Fujian, China
Tianpeng Jiao, Xiamen Key Laboratory of Lithium Battery Energy Storage Application Materials and Safety; Xiamen Hithium Energy Storage Technology Co., Ltd, Xiamen, 361000, Fujian, China

Document Type

Article

Corresponding Author(s)

Jianming Zheng(Jianming.Zheng@hithium.com);
Tianpeng Jiao(jiaotp@hithium.com)

Abstract

Lithium nickel oxide (Li₂NiO₂), as a sacrificial cathode prelithiation additive, has been used to compensate for the lithium loss for improving the lifespan of lithium-ion batteries (LIBs). However, high-cost Li₂NiO₂ suffers from inferior delithiation kinetics during the first cycle. Herein, we investigate the effects of the cost-effective Cu substitution of Li₂Ni_1-xCu_xO₂ (x = 0, 0.2, 0.3, 0.5, 0.7) synthesized by high-temperature solid-phase method on the structure, morphology, electrochemical performance of graphite‖LiFePO₄ battery. The X-ray Diffraction (XRD) refinement result demonstrates that Cu substitution strategy is favorable for eliminating the NiO_x impurity phase andweakening Li-O bond. Analysis on density of states (DOS) indicates that Cu substitution is good for enhancing the electronic conductivity, as well as reducing the delithiation voltage polarization confirmed by electrochemical characterization. Therefore, the optimal Li₂Ni_0.7Cu_0.3O₂ delivers a high delithiation capacity of 437 mAh·g^-1, around 8% above that of the pristine Li₂NiO₂. Furthermore, graphite‖LiFePO₄ pouch cells with a nominal capacity of 3000 mAh demonstrate a notably improved reversible capacity, energy density and cycle life through introducing 2 wt% Li₂Ni_0.7Cu_0.3O₂ additive, delivering a 6.2 mAh·g^-1 higher initial discharge capacity and achieving around 5% improvement in capacity retentnion at 0.5P over 1000 cycles. Additionally, the post-mortem analyses testify that the Li₂Ni_0.7Cu_0.3O₂ additive could suppress solid electrolyte interphase (SEI) decomposition and homogenize the Li distribution, which benefits to stabilizing interface between graphite and electrolyte and alleviating dendritic Li plating. In conclusion, Li₂Ni_0.7Cu_0.3O₂ additive offers advantages such as lower cost, lower delithiation voltage and higher prelithiation capacity compared with Li₂NiO₂, making it a promising candidate of cathode prelithiation additive for next-generation LIBs.

Graphical Abstract

Keywords

Li2Ni1-xCuxO2, cathode prelithiation additive, LiFePO4 battery, cycle life, grid energy storage

DOI

10.61558/2993-074X.3515

Online Date

12-13-2024

Recommended Citation

Jianming Zheng, Jingwen Zhang, Tianpeng Jiao. Enhancing Cycle Life of Graphite‖LiFePO4 Batteries via Copper Substituted Li₂Ni_1-xCu_xO₂ Cathode Prelithiation Additive[J]. Journal of Electrochemistry, doi: 10.61558/2993-074X.3515.