高能量锂离子电池硅基负极黏结剂研究进展

High energy density lithium-ion batteries

硅材料具有较高的理论容量,被视为发展高能量锂离子电池的重要材料之一。但是硅在充放电循环中体积变化较大,会导致负极材料粉化,严重影响电池的电化学性能。黏结剂作为电极的重要组成部分,对于稳定负极结构,改善电池性能具有重要作用。总结归纳了合成类聚合物、生物类聚合物等硅基负极黏结剂的研究进展,合成类聚合物主要包括聚丙烯酸类、聚偏二氟乙烯类以及导电类黏结剂,生物类聚合物主要包括羧甲基纤维素类、海藻酸钠类以及其他生物类黏结剂。分析了选择硅基负极黏结剂的条件,包括要有极性官能团、具有一定的弹性和机械强度、化学稳定性高、最好具有一定的导电性等。极性基团可以与硅表面的羟基形成氢键,增强材料之间的黏结性能,为了更好地制约硅的体积膨胀,可以对其进行改性,使其具有一定的弹性和自愈能力;也可以选择一些导电物质,使黏结剂本身具有导电性能,可以提高电极内部导电网络的稳定性并提高活性物质的含量等。本文也为黏结剂的选择和发展提供了思路。

Silicon is an important material in the development of high specific energy lithiumion batteries due to its high theoretical capacity.However,during the cycle process,silicon has huge volume changes.This causes the negative material to be pulverized and fall off,which affects the battery’s electrochemical performance.As an important part of the electrode,the binder can stabilize the anode structure and improve battery performance.Thus,this review summarizes research related to silicon-based anode binders,e.g.,synthetic polymer and biopolymer binder.Synthetic polymer binders primarily include polyacrylic acid,polyvinylidene fluoride,and conductive binders,and biopolymer binders primarily include carboxymethyl cellulose,sodium alginate,and other biological binders.The selection conditions of a silicon-based anode binder are analyzed in this paper.The silicon-based anode binder should have polar functional groups,certain elasticity and mechanical strength,high chemical stability,and preferably certain conductivity.Polar groups can form hydrogen bonds with hydroxyl groups on the surface of silicon to enhance the bonding properties between materials.To better restrict the volume expansion of silicon,it can be modified to possess elastic properties and self-healing ability.Some conductive materials can also be selected to make the binder have conductive properties.This can improve the stability of the conductive network inside the electrode and increase the content of active substances.In addition,concepts related to the selection and development of a binder are discussed.