基于离子交换机理的尖晶石型LiMn2O4脱/嵌锂模拟

基于离子交换机理,以ICSD(The Inorganic Crystal Structure Database)中LiMn_2O_4的结构数据为基础,利用Materials Studio软件包中Visualizer模块和CASTEP模块构建并优化了尖晶石型LiMn_2O_4和HMn_2O_4以及λ-MnO_2的晶体结构,并通过对比涉及各自晶体结构的系统能值、晶胞参数、键长及键角等的变化,初步验证了离子筛提锂过程是自发吸热过程;分别通过对LiMn2O4和HMn2O4添加H和Li,模拟考察了脱锂和嵌锂(即酸洗和吸附)过程中的活性原子位及H和Li的迁移轨迹,得出8a位置Li和H的离子性较强,脱锂为H置换四面体8a位置Li,并与邻近位置O形成键长约为0.098 9nm的O-H键;嵌锂为Li取代8a-16c-8a孔道中8a位置H的动力学过程。研究结果对锰基离子筛提锂的后续工作具有一定的指导意义。

Simulation of Spinel LiMn2O4 for Lithium Insertion/Extraction Based on Ion Exchange Mechanism

Basing on the mechanism of ion exchange and according to the structure data of LiMn2O4 in the inorganic crystal structure database (ICSD),the crystal structures of LiMn2O4,HMn2O4 and λ-MnO2 were established and optimized by the CASTEP module of Materials Studio software.The process of extracting lithium with ionic sieve was spontaneous and endothermal,which was preliminary verified through comparing the system energy,cell parameters,and bond length and angels of LiMn2O4 and HMn2O4 crystal structures.Active atom positions and migration trajectories of H and Li were simulated in LiMn2O4 and HMn2O4 crystal structure through adding H/Li.It was shown that Li or H at 8a site had strong ionicity,and O-H bond formed between the H replacing Li and the O neighboring 8a site in tetrahedron.The average O-H bond length was 0.098 9 nm.Furthermore,there was a tendency that H was substituted by Li in 8a-16c-8a channel crystal model,which was the process of lithium extraction from solution.The results had a certain guiding significance for further study of extracting lithium mechanism in lithium ionic sieve.