摘要
石墨烯用于Na^(+)电池能够提供的离子嵌入位置非常有限,导致电池的电活性和电容量比较低,影响了充放电特性.为寻找全新的Na^(+)电池负极材料,构造3种不同的F^(-)基团的吸附位置,即Ti1原子顶部(第一种构型Ⅰ-Ti_(3)C_(2)F_(2))、C原子顶部(第二种构型Ⅱ-Ti_(3)C_(2)F_(2))、Ti2原子顶部(第3种构型Ⅲ-Ti_(3)C_(2)F_(2))并计算了3种构型的稳定性及Na^(+)存储能力.计算结果表明:F^(-)官能团可降低形成能,增强结构稳定性,同时在两层异质结界面处的原子层间距增大,有利于Na^(+)的嵌入和脱嵌.对于Ti_(3)C_(2)以及3种结构的Ti_(3)C_(2)F_(2),Na^(+)最稳定的吸附位置分别在Ti1原子顶部、S原子顶部以及Ti2原子顶部.随着介电常数的增大,Na^(+)的吸附能也随之增大,尤其对Ⅰ-Ti_(3)C_(2)F_(2)和Ⅲ-Ti_(3)C_(2)F_(2)的影响非常明显.对于Ⅰ-Ti_(3)C_(2)F_(2)和Ⅲ-Ti_(3)C_(2)F_(2),电解液能够降低扩散势垒,提升充放电速度.Ⅰ-Ti_(3)C_(2)F_(2)和Ⅲ-Ti_(3)C_(2)F_(2)的OCV曲线整体下降平缓、开路电压高,是理想的储能材料.
The ion insertion positions provided by graphene for Na^(+)batteries are very limited,resulting in low electrical activity and capacities of the battery,which affects the charging and discharging behaviors.In order to search for a new kind of negative electrode material for Na^(+)batteries,three different adsorption sites of F-groups were constructed,namely the top of Ti1(Ⅰ-Ti_(3)C_(2)F_(2)),the top of C(Ⅱ-Ti_(3)C_(2)F_(2)),and the top of Ti2(Ⅲ-Ti_(3)C_(2)F_(2)).The stability and Na^(+)storage capacity of the three configurations were also calculated.The calculation results indicate that the F-functional group can reduce the formation energy,enhance structural stability,and increase the atomic layer spacing at the interface between the two heterojunctions,which is beneficial for the insertion and detachment of Na^(+).For Ti_(3)C_(2)and three Ti_(3)C_(2)F_(2)structures,the most stable adsorption sites for Na^(+)are at the top of Ti1 atom,S atom,and Ti2 atom,respectively.As the dielectric constant increases,the adsorption energy of Na^(+)also increases,especially for I-Ti_(3)C_(2)F_(2)andⅢ-Ti_(3)C_(2)F_(2).ForⅠ-Ti 3C 2F_(2)andⅢ-Ti 3C 2F_(2),the diffusion barrier can be reduced due to the electrolyte,which is beneficial for rapid charging and discharging.The OCV curves forⅠ-Ti 3C 2F_(2)andⅢ-Ti 3C 2F_(2)show a gradual decline and a high open-circuit voltage,making them ideal candidates for energy storage materials.
作者
董明慧
张燕
申世英
柳娜
赵淑萍
DONG Ming-hui;ZHAGN Yan;SHEN Shi-ying;LIU Na;ZHAO Shu-ping(College of Engineering,Shandong Xiehe University,Jinan 250107,China)
出处
《兰州理工大学学报》
北大核心
2025年第3期64-72,共9页
Journal of Lanzhou University of Technology
基金
山东省教育厅青创科技支持计划(2021KJ088)。
