(Invited) Multifunctional Binders for High-Performance Rechargeable Batteries

Abstract

Secondary battery plays a significant role in our daily life as well as in modern smart grids, which typically consists of an electrolyte and two electrodes determining the key parameters of the battery. Despite a small dose that usually less than 10%, the binder is a crucial component to keep the electrode integrity and ensure the high electrochemical performance. What`s more, the modification of binder could be conducted to alleviate or even eliminate the side effects raised by failure behaviors of the electrode active materials. However, the state-of-the-art binder optimization strategies still fall behind the rapid development of the novel electrode materials.To improve the energy density of secondary batteries, high-capacity electrode materials have been explored, including silicon, sulfur, layered oxides, etc. However, their practical applications are hindered by various failure behaviors. Take Si as an example, though the Si-based anodes exhibit high capacity up to 4200 mA g-1, they undergo huge volumetric expansion (≈400%) during the electrochemical reactions, resulting in the cracking of active material particles, electrode exfoliation, continuous electrolyte consumption and progressive SEI formation. As a consequence, the capacity of Si-based electrode decreases dramatically along with cycling. The conventional binders that have been widely used in the rechargeable battery systems are typically linear polymers, which are unable to endure the high volume change and address other challenges raised by electrode materials such as low conductivity, unstable bulk structure and interface, etc. To increase the mechanical strength and the electrochemical stability of electrodes, the design of multi-functional binders is considered to be an effective strategy to meet various requirements of advanced binders for high-performance batteries simultaneously.In this work, the synthesis and characterization of multifunctional binders for high-capacity electrode materials are demonstrated. By the introduction of intermolecular forces and chemical bonds, 3D networks are constructed and the ability for volume change accommodation are enhanced as well as the binding force. Moreover, the dynamic crossed links also endow the binders with self-healing ability, which could help to remedy the cracking issues in the advanced electrode materials. Due to the merits of the as-synthesized binders, the electrochemcial performance of the high-capacity electrode is significantly improved, demonstrating a promising strategy for next-generation energy storage systems.