摘要
研究锂空气电池石墨烯正极介观传质的机理,采用Materials-studio软件构建包含石墨烯、H_(2)O、OH^(-)、Li^(+)和O_(2)的介观模型,并应用粗粒化分子动力学的方法对体系中各珠子的传质特性进行介观分析,研究温度、石墨烯层数、石墨烯种类和石墨烯浓度对H_(2)O、OH^(-)、Li^(+)和O_(2)各珠子扩散系数的影响,以及对Li^(+)-OH^(-)、H_(2)O-O_(2)各珠子径向分布函数的影响。结果表明,随着体系内温度的升高,H_(2)O、OH^(-)、Li^(+)和O_(2)的扩散系数增大,Li^(+)-OH^(-)、H_(2)O-O_(2)径向分布函数峰值降低,分布的有序性降低;随着石墨烯层数的增加,H_(2)O、OH^(-)、Li^(+)和O_(2)的扩散系数减小,Li^(+)-OH^(-)、H_(2)O-O_(2)径向分布函数的峰值不变;随着不同层数石墨烯种类和浓度的增加,H_(2)O、OH^(-)、Li^(+)和O_(2)的扩散系数减小。因此,控制体系温度,减少石墨烯的层数,有利于体系中各珠子扩散系数的提升,提升锂空气电池的整体性能。
The mechanism of positive electrode mesoscopic mass transfer of graphene in lithium-air battery was studied.Materials-studio software was used to construct mesoscopic models including graphene,H_(2)O,OH^(-),Li^(+)and O_(2),and the mesoscopic analysis of mass transfer characteristics of each bead in the system was carried out by means of coarse-grained molecular dynamics,the effects of temperature,number of graphene layers,types of graphene and graphene concentration on the diffusion coefficients of each bead of H_(2)O,OH^(-),Li^(+)and O_(2),as well as the radial distribution functions of each bead of Li^(+)-OH^(-)and H_(2)O-O_(2) were studied.The results shown that with the increase of temperature in the system,the diffusion coefficients of H_(2)O,OH^(-),Li^(+)and O_(2) increased,the radial distribution function peak value of Li^(+)-OH^(-)and H_(2)O-O_(2) decreased,and the distribution order decreased.As the number of graphene layers increased,the diffusion coefficients of H_(2)O,OH^(-),Li^(+)and O_(2) decreased,and the peak values of the radial distribution functions of Li^(+)-OH^(-)and H_(2)O-O_(2)remained unchanged.The diffusion coefficients of H_(2)O,OH^(-),Li^(+)and O_(2) decreased with the increase of different graphene types and concentrations.Therefore,controlling the temperature of the system and reducing the number of graphene layers were conducive to the improvement of the diffusion coefficient of each bead in the system and the overall performance of the lithium-air battery.
作者
沈鑫
孙红
李洁
刘思丹
Shen Xin;Sun Hong;Li Jie;Liu Sidan(School of Mechanical Engineering,Shenyang Jianzhu University,Shenyang 110168)
出处
《化工新型材料》
CAS
CSCD
北大核心
2021年第8期159-164,168,共7页
New Chemical Materials
基金
国家自然科学基金(51776131)
辽宁省“兴辽英才计划”项目(XLYC1802045)。
关键词
锂空气电池
石墨烯
传质
介观模拟
lithium-air battery
graphene
mass transfer
mesosscopic simulation
