Environmentally friendly technology for recycling spent lithium-ion battery (LIB) electrodes was developed to explore the efficiency of regenerated electrocatalysts for electrochemical oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). First, LixCoO2 electrodes from spent LIBs were subjected to a lixiviation process using tartaric acid as the lixiviant and H2O2 as an oxidizing agent; then, graphite was converted into graphene oxide (GO), which was combined with lixiviant to regenerate different ratios of cobalt oxide-supported reduced graphene oxide (Co3O4/rGO). The regenerated composite material displayed good ORR activity with an onset potential of 0.936 V vs. RHE. The catalytic activity of Co3O4/rGO towards MOR was also investigated, exhibiting a mass activity of 49.3 A g−1. These findings demonstrate that end-of-life LIBs may be utilized as high-performance electrocatalysts in energy conversion devices which realize resource conservation in addition to minimizing associated environmental issues.