Aqueous processing of natural graphite particulates for lithium-ion battery anodes and their electrochemical performance

Aqueous-based natural graphite particulates for fabrication of lithium-ion battery anodes are investigated with emphasis on chemical control of suspension component interactions among graphite particulates, sodium carboxymethyl cellulose (CMC), and emulsified styrene butadiene rubber (SBR). The chemical stability and dispersion properties of the natural graphite particles are characterized using electroacoustic, flow behaviour and green microstructural observations, as well as by measurement of pore size. Correlation is made between the dispersion characteristics and the electrochemical performance of the particles. The dispersion stability of the graphite suspension is improved by charge development when both SBR and CMC are incorporated into the graphite suspension, compared with an unstable graphite suspension prepared with CMC alone. A method to improve the dispersion and homogeneity of the suspension component based on the use of SBR and CMC is proposed. Electrochemical experiments using a Li-organic electrolyte-as-cast natural graphite half-cell and 750-mAh lithium-ion cells show an initial discharge capacity above 340 mAh g−1, improved charge-discharge efficiency, and excellent rate capability.