Efficient and cost-effective hybrid composite materials based on thermoplastic polymer and recycled graphite

Abstract

Recycling of anode materials from lithium-ion batteries (LIBs) has been given less attention due to the abundance of graphite in the nature, the main material used in LIB anode layers, and its favorable cost. When concerns about environment and shortage of graphite resources become the main objective, then recycling of anode materials can play a significant role in this case. In this work, the graphite anode powder was recycled from LIBs in a very simple procedure including sequence steps of separation, dispersion and heat treatment. The reclaimed anode graphite powder was dispersed in ethanol then centrifuged five times, followed by a heat treatment process at 800 °C for 6 h under continuous nitrogen flow. Recycled graphite was directly used to synthesize hybrid composites by extrusion process. This type of graphite/polymer composites has the potential to be used as conductive polymer composites (CPCs). These composites have versatile functionalities that allow them to be used in several applications such as interference shielding and electrostatic dissipation. The structure, morphology, mechanical properties and electrical conductivity of the hybrid composites were analyzed by XRD, Raman spectroscopy, electron microscope, universal testing machine (UTM) and two probe method. Results showed that mechanical properties of the polymer were significantly improved with the increasing content of the recycled graphite. Morphology also indicated that the recycled graphite was homogeneously distributed in the polymer matrix compared to commercial graphite. Interesting results were observed in mechanical properties when the tensile strength and elongation percentage were compared between composites made from commercial graphite and recycled graphite. Recycled graphite based hybrid composite shows higher elongation and tensile strength compared to commercial graphite based hybrid composite. Conductivity of HDPE-recyl-GR-5% hybrid composite showed 3.81 × 10−8 S/cm, which is 10 orders of magnitude higher than that of HDPE polymer (1.17 × 10−18 S/cm) (insulator level, < 10–12 S/cm).