Importance of binder compositions to the dispersion and electrochemical properties of water-based LiCoO2 cathodes

The effects of the styrene–butadiene rubber (SBR) to sodium carboxymethyl cellulose (CMC) blending ratio of the water-based SBR/CMC binder on the dispersion and the physical and electrochemical properties of LiCoO2 electrodes are studied. Based on the results of dispersion analyses, it is determined that CMC is efficient in dispersing LiCoO2, and the dispersion of the LiCoO2 electrode slurry becomes better when the fraction of SBR in the binder is decreased. Based on physical and electrochemical measurements, however, decreasing the SBR fraction makes the distribution of the binder in the dried electrode sheet less uniform, which results in decreased adhesion strength and increased surface resistance of the electrode sheets. In addition, this study reveals that the binder distribution has a greater influence on the electrical and electrochemical properties of the LiCoO2 electrodes than the dispersion of cathode powders has.

► Increasing [SBR] of SBR/CMC binder blend uniforms binder distribution in cathodes.
► Increasing [SBR] of SBR/CMC causes higher agglomeration of active powders.
► Binder uniformity rather than the powder dispersion dominates the cell performance.