Electrochemical Properties of Unused Graphite Electrode Composite after Exfoliation and Recoating

The cost benefits of recycling graphite electrodes are low; therefore, studies are few on graphite electrode recycling despite the need for lithium-ion battery electrode recycling in achieving efficient carbon neutrality. Here, we investigated the physical properties and battery performance of a composite material exfoliated from a foil during battery production. The surfaces of the exfoliated graphite particles contained binder components, which decreased the charge/discharge capacity and increased the charge-transfer resistance (Rct) of the material. The binder content had a significant effect on the Rct, and carboxymethyl cellulose was more sensitive to an increase in the Rct than styrene–butadiene rubber. When the exfoliated graphite composite was heat-treated, the binder components were removed, and the surface of the graphite particles was modified. The higher the heat treatment temperature, the lower the Rct; after heat treatment at 600 °C, the Rct was 45% lower than that of pristine graphite. In contrast, the cycle durability of exfoliated graphite treated at 600 °C was reduced due to the exposure of excessively active graphite surfaces. Heat treatment at intermediate temperature (450 °C) provided the graphite surface structure whereby both Rct reduction and durability could be achieved.