APPLICATIONS OF TECHNOLOGY:
- Lithium rechargeable batteries
- Yields superior electrode performance
- Electrically conductive and flexible, enabling safe use of silicon materials
- Compatible with current battery manufacturing process
- Avoids need for expensive, toxic solvents
Gao Liu and colleagues at Berkeley Lab have developed polymer electrode binders / adhesives that accommodate silicon electrode materials used in lithium ion batteries. Since the Berkeley Lab emulsion binders are flexible enough to accommodate the significant volume changes expected during charge and discharge cycles, they are particularly suitable for silicon-based electrodes, and they yield superior electrode performance.
By coupling the advantages of conductive polymer binders and the aqueous battery electrode coating process, versatile emulsion polymerization methods were developed to prepare a series of conductive polymer binder emulsions in water. These emulsions consist of side-chain conducting polymers that were dispersed in aqueous solution into nanosize adhesive and conductive suspension particles. Both homopolymer and copolymer emulsions in water were synthesized and successfully used as the binder for silicon containing anode materials, with the mechanical properties of the emulsion particles varying according to the copolymers. The increase in the amount of aromatic units in the polymer binders increased capacity when the polymer emulsions are combined with carboxymethyl cellulose (CMC) as the binder, the cells can achieve about 880 mAhg-1 initial capacity, close to the theoretical value for the active materials consisting of 17% silicon and 83% graphite, with about 75% capacity retention at 200 cycles. Additional details are available in the researchers’ publication, linked below.
The Berkeley Lab binders are compatible with current battery manufacturing process and possess a host of advantages for the industry such as improved electronic connection for active materials in the electrode matrix and reduced need for conductive additives. In addition to saving energy and time, the process avoids the need for toxic organic solvents, thus rendering the electrode coating process low-cost and less hazardous to the human health and environment. Ultimately, these novel polymer emulsion binders have enabled silicon materials to be successfully fabricated into electrodes that demonstrate promising cycling performance.
DEVELOPMENT STAGE: Proven principle
FOR MORE INFORMATION:
Zheng, T., Zhang, T., de la Fuente, M., Liu, G. “Aqueous emulsion of conductive polymer binders for Si anode materials in lithium ion batteries,” European Polymer Journal, 114, (2019), 265-270.
STATUS: Patent pending. Available for licensing or collaborative research.
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