超低界面阻抗/超短传输距离全陶瓷钠离子膜电池的设计与机制研究

Nowadays, the researcher’s interesting for rechargeable batteries shifts from small power sources of personal electronics to large-score energy storages for electricity grids, which pose grand challenges to the storage of electricity at high density, low cost, enhanced safety, and easy fabrication requirements. So far, all ceramic battery has not been widely used in rechargeable ion batteries. First, when operated at room temperature, their ionic conductivities are generally too low to meet the required current density. Second, high electrode/electrolyte interfacial resistance and long transmitting distanceare still the important challenge for solid electrolytes further application. In this proposal, based on the novel high-speed plasma spray technology, a three-layer (porous/dense/porous) electrolyte structure was developed as skeletal structure, and then the selected electrode solutions were introduced into the porous electrolyte layer by dipping coating method to build a tight bond with porous electrolyte layer.In addition, in order to obtain an adequate understanding of the Na+ conduction mechanism in the 3D composite electrodes and the electrolyte/electrode interface, it is necessary to execute calculation along with advanced computational methods. Na+ transport trajectories were investigated via MATLAB system, and in turn, the obtained calculating data can guide for the design of all-ceramic sodium ion battery model structure.

全陶瓷钠离子电池在规模化储能应用中具有低成本、高安全性、易模块化等优势。但电池固­固接触面的高界面阻抗、长迁移距离、有限传输路径等问题限制了其进一步应用。因此本课题拟设计一种具有超低界面阻抗及超短离子传输距离的全陶瓷钠离子膜电池；以改良等离子喷涂工艺构筑多孔/致密/多孔三层电解质 (如Na-β"-Al2O3) 膜结构，以多孔电解质为骨架，通过浸渍工艺制备紧密包覆在多孔电解质上的电极层(如P2 -Na2/3[Fe 1/2Mn1/2]O2，Na2Ti3O7电极)，达到提高界面润湿性、降低界面阻抗、缩短离子在电极与电解质间传输距离的目的，制备高性能全陶瓷钠离子膜电池。基于实验测试与分子动力学计算结果，建立复合电极层／固­固界面效应与电池性能的构效关系，阐释钠离子传输机制。

构筑具有超低界面阻抗/超短传输距离的全陶瓷钠离子膜电池；构筑紧密结合的三维混合电极层以及电解质/电极界面层的几何模型和结构数学模型，模拟钠离子的传输路径。结合实验测试与理论模拟结果，明确阐释复合电极层与界面处对钠离子传输的影响，为全陶瓷钠离子膜电池的发展提供理论支持。本课题通过构筑孔/密/孔结构的三维电解质骨架、与多孔电解质结合紧密的混合电极层，降低电池界面阻抗、缩短钠离子传输距离，缓解固-固界面效应，达到降低全陶瓷钠离子电池过高的固­固界面阻抗的目的。另外，构筑三维电解质/混合电极层以及电解质/电极界面间的结构数学模型，计算钠离子传输的反应参数。结合原位 XRD 及 EIS 测试结果验证结构模型的正确性。为设计出高性能全陶瓷基Li、NA离子电池提供坚实的实验基础和方法论的指导。 本工作设计并构筑了竖排对齐的三层全陶瓷锂离子电池，将低电导率的电极材料构筑在高电导率的电解质孔道内，形成了锂离子传输的高速公路；薄而致密的中间电解质层，使得锂离子的传输距离变短，降低电解质晶界阻抗；在电解质孔道中原位合成电极材料，利于减小界面电阻。设计出一种新颖的具有上下两层微孔道电解质膜和中间一层致密电解质膜，孔道内原位浸渍的固态电解质。解决了电极材料电导率差的限制性问题，同时解决了电极和电解质的界面问题。