Strategies of binder design for high-performance lithium-ion batteries: a mini review

Developing high-performance lithium-ion batteries (LIBs) with high energy density, rate capability and long cycle life are essential for the ever-growing practical application. Among all battery components, the binder plays a key role in determining the preparation of electrodes and the improvement of battery performance, in spite of a low usage amount. The main function of binder is to bond the active material, conductive additive and current collector together and provide electron and ion channels to improve the kinetics of electrochemical reaction. With the ever-increasing requirement of high energy density by LIBs, technical challenges such as volume expansion and active material dissolution are attracting worldwide attentions, where binder is thought to provide a new solution. There are two main categories (organic solvent soluble binder and water-soluble binder) and abundant polar functional groups providing adhesion ability. It is of great significance to timely summarize the latest progress in battery binders and present the principles for designing novel binders with both robust binding interaction and outstanding electrode stabilization function. This review begins with an introduction of the binding mechanism and the related binding forces, including mechanical interlocking forces and interfacial forces. Then, we discussed four different strategies (the enhancement of binding force, the formation of three-dimensional (3D) network, the enhancement of conductivity and binders with special functions) for constructing ideal binder system in order to satisfy the specific demands of different batteries, such as LIBs and lithium–sulfur (Li–S) batteries. Finally, some prospective and promising directions of binder design are proposed based on the existing and emerging binders and guide the development of the next-generation LIBs.