阳极材料的表面改性

2025-03-26

目前，锂离子电池已显示出非常广泛的应用，而阳极材料是决定锂离子电池电化学性能（如储能和转换）的关键因素之一。通过对碳阳极材料的表面改性，可以有效提高锂离子电池的性能，如改善比容量、首次库仑效率、充放电效率、倍率性能、循环稳定性、安全性，延长使用寿命。表面改性的主要方法和机制包括表面涂层、化学处理和元素掺杂：

(1) Surface coating: a “protective film” is constructed to cover the graphite surface to form a “core-shell structure”, which can avoid the peeling of graphite lamellae caused by solvation and improve the cycle stability of electrode materials. The coating of metal and its oxide can also reduce the resistance of lithium ion transfer and charge migration and improve the electrochemical performance of graphite materials.

(2) Chemical treatment: surface oxidation introduces oxygen-containing functional groups, increases the active site, forms a stable SEI film at the interface between anode material and electrolyte, and improves the cycle stability of carbon anode. Surface halogenation can form a passivation film with high intermolecular force on the surface of the material, which can improve the stability of the microcrystalline structure.

(3) 元素掺杂：将金属或非金属元素掺入碳阳极材料中，以改变碳微晶的结构和电子排布，从而改善阳极材料中锂离子的去除和插入的电化学行为。

经过表面改性后，碳阳极材料的电化学性能可以得到大幅提升，但每种改性方法的实际操作和调控仍会影响最终的改性效果。例如，涂层厚度、化学处理的程度以及异原子掺杂剂量的均匀性、分布和扩散都会影响材料的最终性能。如果控制不好，锂离子电池的性能不会提升，反而会导致电化学性能下降。