基于铝氧键稳定的隧道型钠离子电池正极材料

钠离子电池隧道型正极材料Na_0.44MnO₂因具有成本低和原料丰富的优势而受到广泛关注，但该类正极材料在循环过程中会发生Jahn-Teller效应，使得产生的锰离子溶出和迁移的结构不稳定。基于铝取代锰后形成的铝氧键的键能高于锰氧键，可在一定程度上解决循环过程中的晶格应变以及锰离子溶出和迁移的问题。本研究采用高温固相法制备Na_0.44Mn_0.95Al_0.05O₂正极材料，利用X射线衍射仪(XRD)和扫描电镜(SEM)考察了制备的正极材料的结构和表面形貌，并考察了该正极材料的电化学性能和动力学性质。该正极可发挥出127.8 mAh/g的高可逆容量，充放电曲线平滑，储钠机制主要以电容控制行为为主。 

A stable tunnel-type cathode material based on Al-O bonds for sodium-ion batteries

Na_0.44MnO₂, a tunnel-type cathode material for sodium-ion batteries, has attracted attention because of its low cost and abundant raw materials. However, the cathode material has the problems of structural instability of manganese ion dissolution and migration caused by the Jahn-Teller effect during Na+ extraction and insertion. The bonding energy of the Al-O bond formed by Al substituted for Mn was higher than that of the Mn-O bond, which could alleviate the problems of lattice strain as well as the dissolution and migration of Mn ions during the cycle. Therefore, Na_0.44Mn_0.95Al_0.05O₂ was prepared by a high-temperature solid-state method. The structure and surface morphology of the prepared cathode material were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performance and kinetic properties of the cathode material were investigated. The cathode displayed a smooth charge-discharge curve with a highly reversible capacity of 127.8 mAh/g. Na+ storage was mainly governed by a capacitive mechanism.