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Mechanism of Degradation of Capacity and Charge/Discharge Voltages of High-Ni Cathode During Fast Long-Term Cycling Without Voltage Margin
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2022-06-07 , DOI: 10.1002/aenm.202201151
Jae Yeol Park 1 , Minji Jo 1, 2 , Seungki Hong 3 , Seunggyu Park 3 , Jae‐Ho Park 1 , Yong‐Il Kim 4 , Sang‐Ok Kim 1, 5 , Kyung Yoon Chung 1, 5 , Dongjin Byun 2 , Seung Min Kim 3 , Wonyoung Chang 1, 5
Affiliation  

The authors reveal the mechanisms of degradation of capacity, charge voltage, and discharge voltage of commercially-available high-nickel cathode material when it is cycled without a voltage margin by two different charge protocols: constant-current charging and constant-current, constant-voltage charging. With repeated constant-current charging, the cathode material changes to a non-periodic cation-mixed state, which causes a relatively low voltage degradation, whereas during constant-current, constant-voltage charging, the cathode material changes from a layered structure to a periodic cation-mixed spinel-like phase, with consequent severe voltage decay. This decay results from a reduction in the equilibrium electrode potential and an increase of overpotential which are aggravated in a periodic cation-mixed state. The findings provide insights into the use of excess Li without charge-voltage margin in high-Ni cathode materials.

中文翻译:

无电压裕度的快速长周期循环过程中高镍正极容量和充放电电压下降的机理

作者揭示了市售高镍正极材料在通过两种不同充电协议(恒流充电和恒流、恒流充电)在没有电压裕度的情况下循环时容量、充电电压和放电电压下降的机制。电压充电。反复恒流充电时,正极材料变为非周期性的阳离子混合状态,导致电压退化相对较低,而在恒流、恒压充电过程中,正极材料由层状结构变为层状结构。周期性的阳离子混合尖晶石相,随之而来的是严重的电压衰减。这种衰减是由平衡电极电位的降低和过电位的增加引起的,这在周期性的阳离子混合状态下会加剧。
更新日期:2022-06-07
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