缓解高压LiCoO2的晶格扭曲,通过离子电池的电离异质共诱导的核心外结构来缓解
Zezhou Lin1, Ke Fan1, Tiancheng Liu1
1Department of Applied Physics and Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China.
Nano-micro letters
|December 11, 2023
概括
一种新的两步兴奋剂策略创建了核心外结构的氧化 (LiCoO2) 阴极. 这种方法提高了高压离子电池的结构稳定性和电化学性能.
科学领域:
- 材料科学 材料科学 材料科学
- 电化学 电化学 电化学
- 固态化学 固态化学
背景情况:
- 元素兴奋剂对于提高离子电池中高压层叠过渡金属氧化物阴极的结构稳定性至关重要.
- 传统的单步联合兴奋剂策略通常会导致小粒度,因为在粒度边界分离出低扩散性兴奋剂,从而阻碍最佳性能.
- 实现大型单晶分层氧化物阴极需要克服与剂扩散和粒度增长相关的局限性.
研究的目的:
- 开发一种新的两步多元合兴奋剂策略,用于合成具有核心外结构的大型单晶层氧化物阴极.
- 研究剂扩散性对由此产生的核心外形态和LiCoO2 (LCO) 的电化学性质的影响.
- 展示该战略在设计高性能离子电池的先进阴极材料方面的潜力.
主要方法:
- 采用两步联合兴奋剂方法,通过利用兴奋剂离子扩散率的差异来创建核心外结构的LiCoO2 (CS-LCO).
- 高扩散性Al3+/Mg2+离子被纳入核心,而低扩散性Ti4+离子丰富了外层.
- 在现场使用X射线衍射 (XRD) 来监测结构变化,并在高压条件下评估电化学性能.
主要成果:
- 富含Ti4+的外 (大约4个小时) 12nm) 具有更强的Ti-O键和Co/Ti替代,有效地减少了氧联结孔和减轻了结构扭曲.
- 在现场XRD证实了c轴格子参数的受约束收缩,表明结构稳定性得到改善.
- 单晶CS-LCO的可逆容量为159.8 mAh g−1,在4.6 V的300个循环后保持89%,在5C时容量为163.8 mAh g−1.
结论:
- 拟议的两步兴奋剂策略成功制造了核心外结构的LiCoO2 (CS-LCO),增强了结构完整性和电化学性能.
- 这种方法有效地控制了补充剂的分布,从而提高了高压离子电池阴极的循环稳定性和高速率能力.
- 该策略可适应各种剂组合,为设计下一代多层氧化物正极材料提供了多功能途径.
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