锂离子/电子在微锂电池多层膜之间界面输运过程的研究

One of the key parts for the lithium microbatteries (all solid state film lithium-ion batteries) is the solid state electrolyte materials with the excellent comprehensive performance such as the high ionic conductivity, wide electrochemical window and no interface reaction and being compatible mechanical behaviors with the electrodes. Garnet-type oxide Li7La3Zr2O12 possesses the high conductivity at room temperature and thus has been regarded as one of solid state electrolytes with great application potential. In this way, it is necessary to further investigate the transport processes of Li-ion/electron through the Li7La3Zr2O12 and relevant interfaces. Combined with molecular dynamics, Monte Carlo simulation and the thermodynamic knowledge, first-principles calculations have exhibited the strong excellence in studying the ion/electron transport mechanism, defect/interface thermodynamics, phase diagram/transition, phonon vibration mode and mechanical properties. In the present project, by these computational materials tools and relevant experimental methods, we will characterize the structural disordering and lithium-ion concerted transport, build the structure-performance relationship between the lithium ion transport activation energy (pathway) and crystal structure, reveal the ionic transport and charge transfer mechanisms at the electrolyte/electrode interface, thus offering the experimental improvement strategy and pushing the application of lithium microbatteries. Another aim of carrying out this project is to cultivate the young researches in China academy of engineering physics.

具有高离子电导、宽电化学窗、与电极不发生界面反应且机械性能(应力/热膨胀系数等）匹配等综合性能优异的固体电解质材料是微锂电池(固态薄膜锂离子电池)的核心。因在室温下具有较高的离子电导率，石榴石结构型氧化物Li7La3Zr2O12被认为是最具有应用前景的固体电解质材料之一。为此，需要对锂离子/电子在其体相及相关界面的输运过程开展系统深入的研究。基于密度泛函理论的第一性原理计算同分子动力学、蒙特卡罗模拟和热力学统计物理相结合已广泛应用于研究锂离子电池材料的锂离子/电子输运机理、缺陷/界面热力学、相图与相变、声子振动模式以及力学性质等。本项目拟通过上述计算材料学方法并结合实验揭示Li7La3Zr2O12结构无序性与协同输运的特征、建立输运活化能及通道与晶体微观结构之间的构效关系、阐明电解质/电极界面离子输运和电荷转移的微观机理等，据此提出改性策略，推动微锂电池的应用。培养中物院青年参研人员。

聚焦具有高离子电导、宽电化学窗、与电极不发生界面反应且机械性能(应力/热膨胀系数等）匹配等综合性能优异的固体电解质材料是微锂电池(固态薄膜锂离子电池)的核心，本项目利用基于密度泛函理论的第一性原理计算、渗流理论和蒙特卡罗洛模拟等计算材料学方法并结合实验验证揭示了最具有应用前景的固体电解质材料之一的Li7La3Zr2O12结构无序性与协同输运的特征、建立了输运活化能及通道与晶体微观结构之间的构效关系并阐明电解质/电极界面离子输运和电荷转移的微观机理。通过跨尺度解析立方相石榴石固态电解质中四面体空位调制的离子输运行为，建立了Li+浓度、四面体占据率和有效载流子浓度之间的定量关系；采用锂浸润Li2CO3-free Li7La3Zr2O12(LLZO)实现了低界面电阻和高锂溶解沉积电流密度；开发出一套基于高通量自动反应筛选界面相和机器学习以评估Li|掺杂Li7La3Zr2O12(LLZOM)界面在各种化学条件下的可能反应和热力学稳定性的计算流程，籍此提出采用具有强M-O键能的M进行掺杂LLZO可提高Li|LLZOM界面热力学稳定性的改性策略；提出利用气体吸放反应来提高固体离子电导率的新概念；提出一种结合“几何分析+键价和计算”快速获得最小能量路径的方法，并成功应用于Li3PS4中的离子输运通道指认；建立了利用介观模型筛选聚合物基复合电解质的计算流程；通过综述锂离子电池负极表面固体电解质膜的多尺度模拟研究进展，强调融合不同时间-空间尺度模拟方法开展固体电解质膜理性设计及综合性能评估的必要性。发表Joule等SCI论文13篇，他引362次、1篇入选ESI高倍引论文；国内外学术会议邀请报告/口头报告/墙报17/10/2次；培养硕士毕业生3名、在读博士生/硕士生1/4名; 访问中物院电子工程研究所506室并做学术报告4次；协助中物院青年参研人员修改青年基金申请书2项(已成功获批1项)。

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