锂离子电池成膜添加剂丙烯基-1,3-丙磺酸内酯还原机理研究

The Reductive Mechanism of Prop-1-ene-1,3-sultone as Solid Electrolyte Interphase Film-forming Additive for Lithium Ion Battery

采用密度泛函理论方法研究了锂离子电池成膜添加剂丙烯基-1,3-丙磺酸内酯(PES)的还原机理.通过B3LYP/6-311++G(d,p)水平的密度函数理论与偏振连续模型(PCM)理论计算结果表明,PES的还原活性优于碳酸丙烯酯(PC),PES较PC优先通过所获得的前线分子轨道能量和电子亲和能被还原形成PES+e.由于PES+e的结构是不稳定的,易于通过破坏C1—O2或O2—S7键而自发重排形成PES-1或PES-2.通过振动频率分析和内反应坐标(IRC)方法优化和确认PES的过渡态(TS).使用自然键轨道(NBO)方法在DFT的B3LYP/6-311++G(d,p)水平上分析沿着最小能量路径(MEP)的稳定点的键顺序和原子电荷分布.基于结构,键顺序和电荷分布结果分析,负电荷大部分分布在PES+e中的—SO2基团上,因此PES+e的成膜机理经历C1—O2或O2—S7的断裂形成稳定的开环环状阴离子自由基(PES-1或PES-2).

The mechanism for the reduction of Prop-1-ene-1,3-sultone（PES） on anode of lithium ion battery is understood by theoretical calculation at the B3LYP/6-311＋＋G（d, p） level of density functional theory with the polarized continuum models（PCM）. It is found that PES in solvent is reduced prior to PC to form PES＋e by the obtained frontier molecular orbital energy and electron affinity. The structure of PES＋e is unstable, and prone to a spontaneous rearrangement to form PES-1 or PES-2 by the breaking of C1—O2 or O2—S7. The transition state（TS） is optimized and confirmed by vibrational frequency analysis and intrinsic reaction coordinate（IRC） method.The bond orders and atomic charge distribution of the stable points along the minimum energy path（MEP） are analyzed using the natural bond orbital（NBO） method at the B3LYP/6-311＋＋G（d, p） level of DFT. The negative charge is mostly distribution on —SO2 group in PES＋e, based on the structures, bond order and Charge distribution analyses, and it is known that PES＋e experiences the breaking of C1—O2 or O2—S7 to form a stable open cyclic anion radical（PES-1 or PES-2）.