表面端基卤化Ti_(3)C_(2) MXene应用于锂离子电池高容量电极材料的研究  

Halogenated Ti_(3)C_(2) MXene as High Capacity Electrode Material for Li-ion Batteries

作　　者：肖美霞[1] 李苗苗 宋二红 宋海洋[1] 李钊 毕佳颖 XIAO Meixia;LI Miaomiao;SONG Erhong;SONG Haiyang;LI Zhao;BI Jiaying(College of Materials Science and Engineering,Xi’an Shiyou University,Xi’an 710065,China;State Key Laboratory ofHigh Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China)

机构地区：[1]西安石油大学材料科学与工程学院,西安710065 [2]中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室,上海200050

出　　处：《无机材料学报》2022年第6期660-668,共9页Journal of Inorganic Materials

基　　金：国家自然科学基金(51801155);陕西省科学基金(2021JZ-53);上海市自然科学基金(21ZR1472900);陕西省教育厅科研计划(21JK0848);西安石油大学研究生创新项目基金(YCS20211059);西安石油大学材料科学与工程学院西安市高性能油气田材料重点实验室项目。

摘　　要：Mxenes以其优异的比表面积、高导电率和组分可调性而受到广泛研究,并用作高效锂离子电池的电极材料。然而,其有限的存储容量以及锂离子扩散引起的剧烈晶格膨胀限制了MXenes作为电极材料的应用。本研究设计了具有代表性的MXene材料卤化(氟化、氯化或溴化)-Ti_(3)C_(2)。采用基于密度泛函理论的范德瓦耳斯修正的第一性原理计算方法研究了表面端基(T=F^(-)、Cl^(-)和Br^(-))修饰对锂离子电池中Ti_(3)C_(2)负极的原子结构、电学性质、力学性质以及电化学性能的影响。研究表明,Ti_(3)C_(2)T_(2)单层具有良好的结构稳定性、力学性质和导电性质。相比Ti_(3)C_(2)F_(2)和Ti_(3)C_(2)Br_(2),Ti_(3)C_(2)Cl_(2)单层具有较大的弹性模量(沿二维薄膜两个方向的弹性模量分别为321.70和329.43 N/m)、较低的锂离子扩散势垒(0.275 eV)、开路电压(0.54 V)和较大的理论存储容量(化学计量比为Ti_(3)C_(2)Cl_(2)Li_(6)时达674.21 mA·h/g),这表明Ti_(3)C_(2)Cl_(2)单层作为锂电池电极具有良好的安全稳定性和充放电速率。此外,端基氯化扩大了层间距,进而提高了Ti_(3)C_(2)Cl_(2)中锂离子的可穿透性和快速充放电速率。本研究表明,表面氯化的Ti_(3)C_(2)纳米薄膜是一种很有前途的锂电池负极材料,为其它的MXenes基电极材料设计与开发提供了重要的设计思路。MXenes have been widely studied for their excellent specific surface area,high conductivity and composition tunability,which have been used as a highly efficient electrode material for lithium-ion batteries(LIBs).However,limited storage capacity and severe lattice expansion caused by Li-ions diffusion restrict the application of MXenes as electrode materials.Here,Ti_(3)C_(2) MXenes with surface halogenation(fluorination,chlorination and bromination)as representative MXene materials were designed.Effects of surface functionalization on the atomic structures,electronic properties,mechanical properties,and electrochemical performance of Ti_(3)C_(2)T_(2)(T=F,Cl and Br)anode in LIBs were investigated using first-principles calculations based on density functional theory with van der Waals correction.The results reveal that Ti_(3)C_(2)T_(2) MXenes exhibit metallic conductivity with improved structural stability and mechanical strength.Compared with Ti_(3)C_(2)F_(2) and Ti_(3)C_(2)Br_(2),Ti_(3)C_(2)Cl_(2) exhibits the large elastic modulus(321.70 and 329.43 N/m along x and y directions,respectively),low diffusion barrier(0.275 eV),high open circuit voltage(0.54 eV),and storage capacity(674.21 mA·h/g)with stoichiometric ratio of Ti_(3)C_(2)Cl_(2)Li_(6),which renders the enhanced rate performance and endures the repeated lattice expansion and contraction during the charge/discharge process.Moreover,surface chlorination yields expanded interlayer spacing,which can improve Li-ion accessibility and fast charge-discharge rate in Ti_(3)C_(2)Cl_(2).The research demonstrates that Cl-terminated Ti_(3)C_(2) is a promising anode material,and provides effective and reversible routes to engineering other MXenes as anode materials for LIBs.

关 键 词：MXenes Ti_(3)C_(2) 表面端基修饰 第一性原理计算 锂离子电池负极 层间距 

分 类 号：TM911[电气工程—电力电子与电力传动]