双氰胺涂层修饰二氧化锰复合材料的构建及其储锌性能提升机制  

Construction of dicyandiamide-coated manganese dioxide composite and its mechanism for improving zinc storage performance

作　　者：卢翠红 杜丹 LU Cui-hong;DU Dan(School of Chemistry and Chemical Engineering,Changsha University of Science and Technology,Changsha 410633,China;Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy,Hunan University,Changsha 410114,China)

机构地区：[1]School of Chemistry and Chemical Engineering,Changsha University of Science and Technology,Changsha 410633,China [2]Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy,Hunan University,Changsha 410114,China

出　　处：《Journal of Central South University》2024年第5期1443-1460,共18页中南大学学报（英文版）

基　　金：Project(51971089) supported by the National Natural Science Foundation of China。

摘　　要：二氧化锰(MnO_(2))由于具有高理论容量、高工作电压和环境友好等优点被认为是水系锌离子电池中最有应用潜力的正极材料之一。然而,由于不稳定的晶体结构及放电时锰溶解等导致其严重的容量衰减。基于此,本论文采用双氰胺(DCDA)对α-MnO_(2)进行表面包覆,并研究了DCDA包覆层对α-MnO_(2)电化学性能的影响机制。结果表明,DCDA包覆层的物理限域作用提高了α-MnO_(2)的结构稳定性并抑制了放电时锰的溶解。更重要的是,DCDA中具有孤对电子的氮原子与阳离子的静电相互作用,放电时可抑制Mn^(2+)的溶解,充电时可促进Mn^(2+)沉积,从而有效地抑制了锰活性物质的流失。与未改性的α-MnO_(2)阴极相比,α-MnO_(2)@DCDA正极的循环稳定性显著提高,在3 A/g的大电流密度下,1500次循环后仍然具有102.6 mA·h/g的稳定容量,容量保持率超过60%。这项工作为实现MnO_(2)基锌离子电池的稳定循环提供了一条有效途径。Manganese dioxide(MnO_(2))is considered one of the most promising cathode materials for aqueous zinc-ion batteries because of its high theoretical capacity,high working voltage,and environmental friendliness.However,its severe capacity fading is caused by unstable crystal structure and manganese dissolution during discharge.Based on these reasons,dicyandiamide(DCDA)was used to coatα-MnO_(2) and the effect mechanism of DCDA on the electrochemical performance ofα-MnO_(2)@DCDA was systematically investigated.The results indicate that the physical confinement function of the DCDA not only improves significantly the structural stability ofα-MnO_(2) but also inhibits dissolution of manganese during discharge.More importantly,electrostatic interaction between nitrogen atoms in DCDA and cations in electrolyte can inhibit Mn^(2+)dissolution during discharge and promote Mn^(2+)deposition during charging,effectively inhibiting the loss of manganese active material.Compared with unmodifiedα-MnO_(2) cathodes,α-MnO_(2)@DCDA cathodes exhibit significantly improved cycling stability,with a stable capacity of 102.6 mA·h/g after1500 cycles at a high current density of 3 A/g,with a capacity retention rate exceeding 60%.This work provides an effective way to achieve stable cycling of MnO_(2)-based zinc-ion batteries.

关 键 词：水系锌离子电池 α-MnO_(2)正极 含氮官能团 

分 类 号：TM912[电气工程—电力电子与电力传动] TB332[一般工业技术—材料科学与工程]