锂硫电池凭借理论能量密度高、原料来源丰富、环境友好等优点，成为极具发展潜力下一代高比能二次电池体系，但当前主要面临硫转化反应动力学缓慢和多硫化物的穿梭效应等技术挑战。引入各类催化材料可以加速硫氧化还原反应进程并有效抑制穿梭效应，但针对锂硫电池的高效催化材料开发仍存在较大的探索空间。本论文采用缺陷工程与异质结策略，通过第一性原理计算，重点解析了过渡金属掺杂氮化硼（TM-BN）、空位引入/非金属原子掺杂硫化钒（VS₂）和WO₃/SnO₂异质结三种催化材料体系的优化设计与吸附/催化性能调控机制。主要研究内容及获得的结论如下：

（1）基于密度泛函理论（DFT），构建过渡金属（Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn）单原子掺杂正交氮化硼（TM-BN）。通过分子动力学模拟（MD），验证了过渡金属原子（TM）在BN表面掺杂的热力学稳定性。TM-BN体系具有较好的导电性，且TM掺杂诱导的电子转移使得对多硫化物吸附能得以提升。通过构建隐式溶剂模型证实了该体系的吸附能力不受溶剂干扰。通过计算反应自由能以及Li₂S分解路径发现，过渡金属原子掺杂可以降低硫还原反应能垒、提升BN催化活性。整体而言，Cr-BN在结构稳定性与催化性能等方面具有良好的均衡表现。

（2）针对VS₂催化材料构建空位/掺杂模型，成功构建硫空位（VS₂-v）和氧、氮、磷原子掺杂（VS₂-O、VS₂-N、VS₂-P）多种催化材料，探究引入空位和掺杂杂原子对VS₂结构与催化性能的影响。研究结果表明，这些体系均具有较好的热力学稳定性和电子导电性，其中VS₂-v对多硫化物的吸附能最弱而VS₂-P的吸附能最强，VS₂-O和VS₂-N对多硫化物的结合能适中，但高于电解液溶剂分子。VS₂-O可以显著降低硫还原反应和Li₂S分解能垒，有望用作锂硫电池的高效催化材料。

（3）利用WO₃和SnO₂两款氧化物构建异质结结构，研究该异质结设计对多硫化物吸附性能和转化反应动力学的影响规律。MD模拟验证了异质结的热力学稳定性。相比单一氧化物，异质结对多硫化物具有适中的吸附强度，有助于促进锂离子和多硫化物的扩散/迁移，降低硫还原反应能垒和硫化锂分解势垒。实验研究证实了WO₃/SnO₂异质结可以显著提升锂硫电池的长周期循环稳定性。

Lithium-sulfur (Li-S) batteries have emerged as a highly promising next-generation high-energy-density secondary battery system due to their advantages of high theoretical energy density, abundant raw materials, and environmental friendliness. However, they currently face significant technical challenges, including slow sulfur conversion kinetics and the polysulfide shuttle effect. Introducing various catalytic materials can accelerate sulfur redox reactions and effectively suppress the shuttle effect, yet substantial exploration remains in developing efficient catalysts for Li-S batteries.

This study employed defect engineering and heterojunction strategies, utilizing first-principles calculations to systematically investigate the optimized design and adsorption/catalytic performance regulation mechanisms of three catalytic material systems: transition metal-doped boron nitride (TM-BN), vacancy-introduced/non-metal atom-doped vanadium sulfide (VS₂), and WO₃/SnO₂ heterojunctions. The main findings are summarized as follows:

(1) Based on density functional theory (DFT), single-atom transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn)-doped orthorhombic boron nitride (TM-BN) was constructed. Molecular dynamics (MD) simulations confirmed the thermodynamic stability of transition metal (TM) atom doping on the BN surface. The TM-BN system exhibits good electrical conductivity, and TM doping-induced electron transfer enhances polysulfide adsorption energy. Implicit solvation models confirmed solvent-independent adsorption capability. Calculations of reaction free energy and Li₂S decomposition pathways revealed that TM doping lowers the energy barrier for sulfur reduction reactions and enhances BNs catalytic activity. Overall, Cr-BN demonstrates a well-balanced performance in structural stability and catalytic properties.

(2) Various vacancy/doping models were constructed for VS₂ catalysts, including sulfur vacancy (VS₂-v) and oxygen, nitrogen, phosphorus atom doping (VS₂-O, VS₂-N, VS₂-P), to investigate the impact of vacancies and dopants on VS₂ structure and catalytic performance. Results indicate good thermodynamic stability and electronic conductivity across all systems. VS₂-v exhibits the weakest polysulfide adsorption, while VS₂-P shows the strongest. VS₂-O and VS₂-N possess moderate polysulfide binding energies, exceeding those of electrolyte solvent molecules. VS₂-O significantly reduces the energy barriers for sulfur reduction and Li₂S decomposition, demonstrating potential as an efficient catalyst for Li-S batteries.

(3) A heterojunction structure was constructed using WO₃ and SnO₂ oxides to study its effect on polysulfide adsorption and conversion reaction kinetics. MD simulations verified the heterojunction's thermodynamic stability. Compared to single oxides, the heterojunction provides moderate polysulfide adsorption strength, facilitating lithium-ion and polysulfide diffusion/migration, and lowering energy barriers for sulfur reduction and Li₂S decomposition. Experimental studies confirmed that the WO₃/SnO₂ heterojunction significantly enhances the long-term cycling stability of Li-S batteries.

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