Template-free synthesis of carbon hollow spheres and reduced graphene oxide from spent lithium-ion batteries towards efficient gas storage

Herein, we report the facile synthesis of carbon hollow spheres (CHS) and reduced graphene oxide (rGO) from separators and graphite recovered from a spent lithium-ion battery (LIB), respectively, towards a “Waste-to-Wealth” approach. Subsequently, both CHS and rGO were employed to explore the gas storage capabilities for storing various gases such as N2, H2, and CO2. For the first time, a facile one-step carbonization process was employed to concoct CHS from the recovered polymer separators without the use of a template. Similarly, the synthesis of rGO was undertaken entirely via the mended graphite and using the outer metallic Al cases as a reducing agent. The specific surface area and total pore volume of rGO and CHS were estimated to be 374 & 402 m2 g−1 and 0.16 & 0.30 cm3 g−1, respectively. Moreover, the H2 uptake at 15 bar and 77 K was found to be 1.78 wt% for rGO and 1.22 wt% for CHS. Interestingly, the acquired rGO from the waste constituents displays a high CO2 uptake of 12 wt% and 33 wt% can be stored in the CHS at 40 bar and 298 K. This study affords the prospect of alternate/efficient gas storage materials by recycling spent LIB in an economically and environmentally friendly approach.