Reduced graphene oxide derived from the spent graphite anodes as a sulfur host in lithium–sulfur batteries†

Abstract

Lithium–sulfur batteries (LSBs) offer a distinctive advantage over traditional Li-ion batteries with a higher theoretical capacity (1675 mA h g⁻¹) and energy density (2600 W h kg⁻¹). This study focuses on an inexpensive graphite recycled from the spent LIBs as a promising sulfur host for developing sustainable LSBs. A recycled reduced graphene oxide–sulfur (RRGO-S) composite was cast onto a 3D-carbon fiber (CF) electrode (RRGO-S@CF). The flexible and lightweight RRGO-S@CF electrodes at 500 mA g⁻¹ delivered an initial discharge capacity of 552 mA h g⁻¹, and there was no capacity loss in its initial five cycles, maintaining a stable capacity of 390 mA h g⁻¹ till 300 cycles with 73% capacity retention. At a higher current density of 1.675 A g⁻¹, it delivered an improved capacity of 417 mA h g⁻¹. The enhanced electrochemical performance was due to the favorable interaction between the RRGO and lithium polysulfides, reducing the active material loss and polysulfide dissolution. The 3D-CF and RRGO offer a conductive network and Li-ion transport with electrolyte wettability, thereby improving the sulfur utilization and overall electrochemical performance in LSBs. This approach demonstrates the construction of recycled materials from the spent LIBs as an inexpensive source to meet the growing energy demand in the practical development of LSBs.