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Trace high-valence ions induced surface coherent phase stabilized high voltage LiCoO2
Energy Storage Materials ( IF 18.9 ) Pub Date : 2024-12-16 , DOI: 10.1016/j.ensm.2024.103950
Muhammad Imran, Zhongsheng Dai, Fiaz Hussain, Wei Xia, Renjie Chen, Feng Wu, Li Li

Employing higher voltage (≥4.6 V) is an effective strategy to achieve higher energy densities in LiCoO2 based lithium-ion batteries. However, higher-voltage operation was generally followed by more severely surface to bulk structure deterioration, leading to rapid battery performance decay. Herein, a co-doping strategy involving in trace high-valence tantalum and niobium doping in LiCoO2 material was proposed. Owing to the charge neutralization effect, the incorporated Ta and Nb ions induced the Co to lower valence state, which could further migrate to the Li layer for the similar ionic radius, and thus a nanoscale disordered layer on LiCoO2 surface was successfully constructed. The stable disordered layer with tiny lattice mismatch to inner layered structure (coherent phase) could serve as an “armor” to restrain surface side reactions with electrolyte. Furthermore, the strong Ta-O and Nb-O bonding could act as an “oxygen anchor” to inhibit excessive oxygen oxidation under high-voltage operation. This helped the modified cathode showed 82 % capacity retention after 100 cycles (4.6 V). Furthermore, the full cell composed of modified cathode and graphite anode revealed a remarkable capacity retention of 98 % after 400 cycles. This study provides deep insights into the different phenomena associated with interfacial and structural parameters that need to be tuned to enhance the electrochemical performance at elevated voltages.

中文翻译:


痕量高价离子诱导的表面相干稳相高压 LiCoO2



采用更高的电压 (≥4.6 V) 是在基于 LiCoO 2 的锂离子电池中实现更高能量密度的有效策略。然而,更高电压的操作通常伴随着更严重的表面到本体结构劣化,导致电池性能迅速衰减。在此,提出了一种涉及 LiCoO 2 材料中痕量高价钽和铌掺杂的共掺杂策略。由于电荷中和作用,掺入的 Ta 和 Nb 离子诱导 Co 达到较低的价态,从而可以进一步迁移到具有相似离子半径的 Li 层,从而在 LiCoO 2 表面成功构建了一个纳米级无序层。与内层结构(相干相)具有微小晶格失配的稳定无序层可以作为抑制表面与电解质的侧面反应的“盔甲”。此外,在高压运行下,强 Ta-O 和 Nb-O 键合可以作为“氧锚”,抑制过度的氧氧化。这有助于改性阴极在 100 次循环 (4.6 V) 后显示出 82.1% 的容量保持率。此外,由改性阴极和石墨阳极组成的全电池在 400 次循环后显示出 98% 的显着容量保持率。这项研究深入探讨了与界面和结构参数相关的不同现象,这些参数需要调整以提高高压下的电化学性能。
更新日期:2024-12-21
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