Enhanced Cycling Stability of 4.6 V LiCoO2 Cathodes by Inhibiting Catalytic Activity of its Interface Via MXene Modification-猫眼课题宝

DOI：

10.1002/adfm.202300589

发表时间：

2023-04

期刊：

Advanced Functional Materials

影响因子：

19

通讯作者：

中科院分区：

材料科学1区

文献类型：

--

作者：

Chao Sun;B. Zhao;Jing Mao;Kehua Dai;Zhen-yu Wang;Linkai Tang;Hengbao Chen;Xia-hui Zhang;Jun‐chao Zheng

LiCoO2具有较高的能量密度，在储能设备中扮演着重要的角色。将充电截止电压提高到4.6V可以显著提高LiCoO2正极的体积能量密度，但4.6V条件下有机电解液和LiPF6分解产生的HF对LiCoO2界面的电阻增加以及由外而内对LiCoO2的损伤不利于循环过程中的结构稳定性。结果表明，通过使用原子薄的MXenes作为中间层来抑制LiCoO2的界面催化活性，可以有效地减缓电解液和LiPF6的分解。密度泛函理论计算结果表明，LiPF6在LiCoO2和MXenes界面的分解能分别为1.13和3.21 eV。飞行时间二次离子质谱仪结果进一步表明，有机电解液和LiPF6的分解产物在MXenes界面上的厚度(5 Nm)比LiCoO2(10 Nm)要薄。本研究为稳定锂离子电池正极界面提供了一种新的、通用的策略，为高能量密度锂离子电池的发展提供了支持。

LiCoO2 plays a key role in energy storage devices due to its high energy density. And the volumetric energy density of LiCoO2 cathode can be significantly improved by increasing the charging cut‐off voltage to 4.6 V. However, the increase in resistance at the LiCoO2 interface, and the damage to the LiCoO2 from the outside to the inside by the HF generated that caused by the decomposition of the organic electrolyte and LiPF6 under 4.6 V conditions are not conducive to structural stability during cycling. Here, it is shown that the decomposition of electrolyte and LiPF6 is effectively mitigated by inhibiting the interfacial catalytic activity of LiCoO2 using an atomically thin layer of MXenes as a interlayer. Density functional theory results suggest that the decomposition energy of LiPF6 is 1.13 and 3.21 eV at the interface of LiCoO2 and MXenes, respectively. Time of Flight Secondary Ion Mass Spectrometry results further indicate that the decomposition products of the organic electrolyte and LiPF6 have a thinner thickness at the interface of MXenes (5 nm) than LiCoO2 (10 nm). This study provides a new and universal strategy for stabilizing the cathode interface to support the development of high energy density lithium‐ion batteries.