Interdisciplinary School of Green Energy, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea.
Acc Chem Res. 2013 May 21;46(5):1161-70. doi: 10.1021/ar200224h. Epub 2012 Apr 18.
Motivated by new applications including electric vehicles and the smart grid, interest in advanced lithium ion batteries has increased significantly over the past decade. Therefore, research in this field has intensified to produce safer devices with better electrochemical performance. Most research has focused on the development of new electrode materials through the optimization of bulk properties such as crystal structure, ionic diffusivity, and electric conductivity. More recently, researchers have also considered the surface properties of electrodes as critical factors for optimizing performance. In particular, the electrolyte decomposition at the electrode surface relates to both a lithium ion battery's electrochemical performance and safety. In this Account, we give an overview of the major developments in the area of surface chemistry for lithium ion batteries. These ideas will provide the basis for the design of advanced electrode materials. Initially, we present a brief background to lithium ion batteries such as major chemical components and reactions that occur in lithium ion batteries. Then, we highlight the role of surface chemistry in the safety of lithium ion batteries. We examine the thermal stability of cathode materials: For example, we discuss the oxygen generation from cathode materials and describe how cells can swell and heat up in response to specific conditions. We also demonstrate how coating the surfaces of electrodes can improve safety. The surface chemistry can also affect the electrochemistry of lithium ion batteries. The surface coating strategy improved the energy density and cycle performance for layered LiCoO2, xLi2MnO3·(1 - x)LiMO2 (M = Mn, Ni, Co, and their combinations), and LiMn2O4 spinel materials, and we describe a working mechanism for these enhancements. Although coating the surfaces of cathodes with inorganic materials such as metal oxides and phosphates improves the electrochemical performance and safety properties of batteries, the microstructure of the coating layers and the mechanism of action are not fully understood. Therefore, researchers will need to further investigate the surface coating strategy during the development of new lithium ion batteries.
受电动汽车和智能电网等新应用的推动，过去十年中，人们对先进锂离子电池的兴趣显著增加。因此，该领域的研究工作已加强，以生产具有更好电化学性能的更安全设备。大多数研究都集中在通过优化晶体结构、离子扩散率和电导率等体性质来开发新型电极材料。最近，研究人员还考虑了电极的表面性质作为优化性能的关键因素。特别是，电极表面的电解质分解与锂离子电池的电化学性能和安全性都有关。在本综述中，我们概述了锂离子电池表面化学领域的主要发展。这些想法将为先进电极材料的设计提供基础。最初，我们简要介绍了锂离子电池的背景知识，例如锂离子电池中发生的主要化学成分和反应。然后，我们强调了表面化学在锂离子电池安全性中的作用。我们研究了正极材料的热稳定性：例如，我们讨论了正极材料的氧生成，并描述了电池在特定条件下如何膨胀和升温。我们还展示了如何通过涂层改善电极的安全性。表面化学还会影响锂离子电池的电化学性能。表面涂层策略改善了层状 LiCoO2、xLi2MnO3·(1 - x)LiMO2（M = Mn、Ni、Co 及其组合）和 LiMn2O4 尖晶石材料的能量密度和循环性能，我们描述了这些改进的工作机制。尽管用金属氧化物和磷酸盐等无机材料对正极进行表面涂层可以提高电池的电化学性能和安全性能，但涂层层的微观结构和作用机制尚不完全清楚。因此，在开发新型锂离子电池时，研究人员将需要进一步研究表面涂层策略。
