三维多孔MnO_(x)@In_(2)O_(3)立方盒子的构筑及储锌性能  

Construction and Zn Storage Performance of Three Dimensional Porous MnO_(x)@In_(2)O_(3) Cubes

作　　者：樊小勇[1] 毋妍 孙瑞波 苟蕾[1] 李东林[1] FAN Xiaoyong;WU Yan;SUN Ruibo;GOU Lei;LI Donglin(School of Materials Science and Engineering,Chang’an University,Xi’an 710061,China)

机构地区：[1]长安大学材料科学与工程学院,西安710061

出　　处：《高等学校化学学报》2021年第6期1816-1825,共10页Chemical Journal of Chinese Universities

基　　金：陕西省国际合作项目(批准号:2020KW-024)资助。

摘　　要：锰基氧化物作为锌离子电池正极具有高比容量和低成本等优点,但在电化学循环过程中不可逆相变、锰的溶解和电极/电解质界面不稳定导致其在小电流密度、深度放电条件下的循环性能差.针对以上问题,合成了三维(3D)多孔MnOx立方盒子,并在其表面包覆In_(2)O_(3)层,获得3D多孔MnO_(x)@In_(2)O_(3)立方盒子.结果显示,MnO_(x)@In_(2)O_(3)立方盒子具有大量孔径约10 nm左右的孔,有利于H^(+)和Zn^(2+)的快速传输;In2O3包覆层均匀包覆于3D多孔MnO_(x)立方盒子的孔壁上,有利于抑制MnO_(x)在电化学循环过程中的不可逆相变和锰的溶解,稳定电极/电解质界面.电化学测试结果表明,该3D多孔MnO_(x)@In_(2)O_(3)电极在0.3 A/g的小电流密度、深度放电条件下能稳定循环400次以上,容量保持260 m A·h/g;在1.8 A/g电流密度下可稳定循环4000次以上,容量保持81m A·h/g;即使在高电流密度6.0 A/g下仍保持73.4 m A·h/g的高可逆容量.恒电流间隙滴定(GITT)和循环伏安测试结果表明,3D多孔MnO_(x)@In_(2)O_(3)电极比3D多孔MnO_(x)具有更高的离子扩散速率,有利于提升其高倍率容量.电化学阻抗谱结果表明,3D多孔MnO_(x)@In_(2)O_(3)电极具有比3D多孔MnO_(x)更稳定的电极/电解质界面,有利于提升其循环寿命.2000次循环后的扫描电子显微镜(SEM)结果表明,MnO_(x)@In_(2)O_(3)电极表面仍分布少量In_(2)O_(3),以确保电极/电解质界面和循环的稳定性.Mn-based oxides have been widely researched as the cathode of Zn-ion batteries due to their high capacity and low-cost.However,their phase transformation,dissolution of Mn and unstable electrode/electrolyte interphase during cycling cause poor cycle lifespan,especially poor lifespan at low current densities and high discharge depth.In this work,three-dimensional(3D)porous MnO_(x) cubes were prepared and then a In_(2)O_(3) layer was coated on their surface to gain 3D porous MnO_(x)@In_(2)O_(3) cubes.The rich pores with size about 10 nm are beneficial to the rapid transport of H^(+) and Zn^(2+),In_(2)O_(3) coating layer is beneficial to suppressing the dissolution of Mn and phase transformation of MnO_(x) electrodes and stabilize the electrode/electrolyte interphase during cycling.The 3D porous MnO_(x)@In_(2)O_(3) electrodes deliver high capacity of 260 mA·h/g after 400 stable cycles at a small current density of 0.3 A/g,which is much better than most of reports.Besides,it also delivers high capacity of 81 mA·h/g after 4000 stable cycles at 1.8 A/g,high capacity of 73.4 mA·h/g even at high current density of 6.0 A/g.The Galvanostatic intermittent titration technique(GITT)and CV results reveal 3D porous MnO_(x)@In_(2)O_(3) electrode has lower electrochemical polarization and large diffusion coefficient than those of 3D porous MnO_(x) electrode.The electrochemical impedance spectra results demonstrate 3D porous MnO_(x)@In_(2)O_(3) electrode has more stable electrode/electrolyte interphase than that of 3D porous MnO_(x) electrode.The SEM images of 3D porous MnO_(x)@In_(2)O_(3) electrode suffered 2000 cycles show a little In_(2)O_(3) still dispersing on the MnOx surface,which ensures the structure stability and stable cyclability.

关 键 词：锌离子电池 正极 锰基氧化物 三维多孔 三氧化二铟包覆 

分 类 号：O646[理学—物理化学]