自组装多级结构在锂离子电池中的应用

The Application of Self-Assembled Hierarchical Structures in Lithium-Ion Batteries

锂离子电池作为比能量最高的二次电池,在可持续能源领域扮演越来越重要的角色。为寻求下一代更高性能的锂离子电池,人们在探索许多高比容量电极材料。然而,这些材料通常具有锂化前后体积变化大、电极阻抗大等缺点,需要制备成纳米结构才能够获得较好的电化学储锂性能。而纳米结构具有比表面积高、振实密度低等缺点,导致电池的首次库仑效率低、循环寿命短和比能量低。将纳米材料组装成多级结构能够有效地降低整体的比表面积、从而限制固体界面膜形成对锂的消耗量,提高首次库仑效率;与纳米颗粒的无序堆积相比,多级结构材料往往具有较高的堆积密度和接触面积,进而提高电池的能量密度。本文主要介绍锂离子电池中多级结构的制备及其在锂离子电池中的应用:制备方面主要介绍了溶剂热法、乳液法、喷雾干燥法和模板法,以及相关参数对最终多级结构的影响;在应用方面,主要针对不同多级结构材料以提高锂离子电池性能为主线进行综述。

Lithium ion batteries,which are secondary battery with the high specific energy,play an increasingly important role in the field of sustainable energy.In order to explore the next generation of lithium ion batteries with higher specific energy density,many electrode materials with high specific capacity are being researched and developed.However,these materials usually display the large volume change during lithiation and delithiation process.Therefore,it is necessary to prepare nanostructures to achieve better electrochemical performance. However,the nanostructure leads to low Coulombic efficiency,poor cycling stability and relatively low specific energy density,which can be ascribed to its high specific surface area and low tap density.The assembly of nanomaterials into a hierarchical structure can effectively reduce the overall specific surface area,and limit the consumption of lithium during the formation of solid state interphase(SEI)film,leading to the increase of the initial Coulombic efficiency.Compared with the disordered build-up of nanoparticles,the hierarchical structure has a higher accumulation density and contact area,thus leading to the decrease of porosity and the increase of build-up density of the electrode materials.Therefore,the hierarchical structure of electrode materials can further increased the specific energy density of lithium ion batteries.In this review,we mainly focus on the preparation of hierarchical structure in lithium ion batteries and its application in lithium ion batteries.In terms of preparation,solvothermal method,emulsion method,spray drying method and template method are mainly described as well as effect of various parameters on the final hierarchical structure.In terms of application, different hierarchical structures are reviewed with the purpose of improving performances of lithium ion batteries as the mainline.