Material and structural design of a new binder for high energy and high power lithium ion batteries

The rapid growth of large-scale energy storage systems, such as electric vehicles, has significantly increased the demand for high-performance lithium-ion batteries. To meet these demands, it is essential to optimize every component of the battery, including electrode materials, electrolytes, and binders. Traditional lithium-ion battery binders typically consist of an insulating polymer combined with a conductive additive. However, during electrode preparation, the active material and conductive phase are randomly distributed, leading to inefficient electron and ion transport. This issue becomes more pronounced when using high-capacity electrode materials, as the electrochemical reactions generate significant mechanical stress that can damage the binder system, ultimately reducing the battery’s cycle life. Therefore, developing a new binder system that offers a stable, low-resistance, and continuous internal pathway across the entire electrode is crucial.

Recently, Professor Yu Guihua (corresponding author) and Dr. Shi Wei from the University of Texas at Austin were invited to contribute a review article to the prestigious journal *Accounts of Chemical Research*, published by the American Chemical Society (ACS). The article, led by Dr. Zhou Xingyi, systematically reviews the latest advances in the material and structural design of high-performance binder systems for lithium-ion batteries. It also discusses simulation techniques and advanced characterization methods used to study the electrochemical behavior of binders, while outlining future directions for the development of multifunctional battery adhesives (Figure 1).

Fig.1 Material and structure design and mechanism study of new lithium ion battery binder

The paper begins by highlighting the use of insulating polymers rich in carboxyl groups as battery binders. These materials provide strong bonding with the active electrode material, ensuring structural stability during electrochemical processes, which leads to high capacity and excellent cycle performance (Figure 2a). However, these insulating-based binders still require conductive additives, limiting further improvements in energy density. In contrast, conductive polymer-based binders offer both adhesion and conductivity, making them a promising alternative for next-generation batteries.

In various studies, researchers have modified the molecular structure of conductive polymers by introducing different functional groups on the main chain, enhancing the binder's mechanical and swelling resistance without compromising its electrical properties (Figure 2b). Professor Yu’s group developed a three-dimensional conductive polymer gel by regulating the microstructure of the polymer, which was then applied as a battery binder (Figure 2c). This flexible and adjustable structure not only facilitates electron and ion transport but also enhances electrode stability and ensures uniform distribution of active particles.

The article also explores the mechanisms behind binder performance, including computational simulations and advanced analytical techniques, and outlines key design principles for future binder systems.

Figure 2 (a) Application of an insulating polymer with a rich carboxyl group in a battery binder. (b) Modulation of the molecular structure of the conductive polymer binder by introducing different functional groups on the main chain. (c) Synthesis of conductive polymer gels and their application in a new generation of battery binders

Looking ahead, the article discusses the future of multi-functional battery binders. Through molecular design and composite material synthesis, new functionalities such as self-healing, flexibility, stretchability, and environmental responsiveness can be integrated into binder systems. Self-healing adhesives have been shown to significantly extend battery life. Recently, Professor Yu’s team developed a composite gel with both conductive and self-healing properties, offering great potential as a next-generation multifunctional battery binder (Figure 3). Similarly, other advanced binders with enhanced mechanical and environmental properties can enable the development of flexible and smart safety batteries.

Figure 3 Synthesis of adhesive with self-healing properties and prospective applications in battery binders