Application of Carboxymethyl Cellulose CMC As a Binder in Batteries

Application of Carboxymethyl Cellulose CMC As a Binder in Batteries

With the development of lithium-ion batteries in the direction of high specific energy, traditional graphite anode materials will gradually be replaced by alloys, metal oxides, and other high specific capacity anode materials. Anode materials with high specific capacity are prone to large volume changes during cycling, which limits their practical applications. Compared with PVDF, a water-based carboxymethyl cellulose CMC binder can significantly improve the electrochemical performance of Si-based electrodes. The reasons why carboxymethyl cellulose CMC is significantly better than PVDF as a binder for high specific capacity negative electrode materials include the fact that it is beneficial to the dispersion of electrode paste does not react with electrolytes and can form chemical bonds with active materials.


Ⅰ. Carboxymethyl cellulose CMC as a binder in batteries


Carboxymethyl cellulose CMC binder has a significant effect on improving the capacity of negative electrode cycle performance, and it has attracted much attention. Carboxymethyl cellulose CMC is a linear derivative of cellulose. Carboxymethyl cellulose CMC has the properties of adhesion, thickening, emulsification, and suspension. So, it is widely used in food, daily chemical, construction, and other fields. It is the cellulose product used in the world most widely.


Ⅱ. Application of carboxymethyl cellulose CMC in lithium-ion batteries


In lithium-ion batteries, carboxymethyl cellulose CMC was first used as an aqueous binder in graphite anode materials. Compared with organic solvent-based adhesives such as PVDF, water-based adhesives are more environmentally friendly and inexpensive, so they have been widely used. Some graphite anodes use a small amount of carboxymethyl cellulose CMC, which can achieve electrochemical performance equivalent to that of PVDF electrodes. At the same time, the presence of carboxymethyl cellulose CMC does not affect the intercalation and deintercalation of Li+ in the graphite layer, nor does it affect the formation of solid electrolyte interface membranes during charge and discharge. It is an excellent binder for lithium-ion batteries. Studies have shown that when carboxymethyl cellulose CMC and SBR are used together, it can increase the dispersion stability of graphite slurry, so carboxymethyl cellulose CMC is often used in conjunction with SBR. Both the degree of substitution and pH of the slurry has a certain effect on the electrochemical performance of the graphite anode.


Ⅲ. Factors affecting the performance of carboxymethyl cellulose CMC electrode


Many factors affect electrode performance. The properties of carboxymethyl cellulose CMC itself and its water-solvent characteristics are very different from the commonly used PVDF. Therefore, the process parameters of carboxymethyl cellulose CMC are studied, and the influencing factors and factors of carboxymethyl cellulose CMC electrodes are searched. Related laws are of great significance to the rational use of carboxymethyl cellulose CMC. Four factors affect the performance of carboxymethyl cellulose CMC electrodes, including Carboxymethyl cellulose CMC parameters such as molecular weight, degree of substitution, and positive ion, carboxymethyl cellulose CMC addition amount, slurry pH value, and electrode porosity.