北京理工大学宋维力团队揭示了单颗粒LiNi1/3Mn1/3Co1/3O2的电化学动力学参数与相应多孔电极性能的关系。相关研究成果发表在2022年6月20日出版的《德国应用化学》。
为了剖析电极尺度上的性能限制因素，需要直接表征微尺度单粒子。
该文中，研究人员建立了一个单粒子电化学装置，并开发了一个基于物理的模型，用于从电化学阻抗测量中提取固相扩散系数（Ds）和交换电流密度（i0）。研究发现，LiNi1/3Mn1/3Co1/3O2表面的碳涂层增强了i0。此外，当截止电荷电压从4.3 V增加到4.4 V时，Ds和i0分别不可逆衰减约25%和约10%。
此外，研究人员还将单个粒子的本征参数与多孔电极的性能关联起来。由i0值较高的活性粒子组装而成的多孔电极可提供更大的容量和更快的容量衰减。该实验和理论相结合的工作中开发的方法，可用于关联其他类似系统的单粒子尺度和多孔电极尺度。
附：英文原文
Title: Correlating Electrochemical Kinetic Parameters of Single LiNi1/3Mn1/3Co1/3O2 Particles with the Performance of Corresponding Porous Electrodes
Author: Xu Li, Na Li, Kai-Lun Zhang, Jun Huang, Shuqiang Jiao, Hao-Sen Chen, Wei-Li Song
Issue&Volume: 2022-06-20
Abstract: Characterizing microscale single particles directly is requested for dissecting the performance-limiting factors at the electrode scale. In this work, we build a single-particle electrochemical setup and develop a physics-based model for extracting the solid-phase diffusion coefficient (Ds) and exchange current density (i0) from electrochemical impedance measurements. We find that the carbon coating on LiNi1/3Mn1/3Co1/3O2 surface enhances i0. In addition, Ds and i0 decay irreversibly by ~25% and ~10%, respectively, when the cutoff charge voltage increases from 4.3 V to 4.4 V. Moreover, we correlate intrinsic parameters of single particles with the performance of porous electrodes. Porous electrodes assembled with active particles with higher i0 values deliver a greater capacity and faster capacity fade. The methods developed in this combined experimental and theoretical work can be useful in correlating the single-particle scale and porous-electrode scale for other similar systems.
DOI: 10.1002/anie.202205394
Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202205394
