Environmentally compatible dimethyl sulfoxide: an alternative to N-methylpyrrolidone for electrochemical performance of recycled LiMn1/3Ni1/3Co1/3O2 in lithium-ion battery

The effect of recycling and doping LiMn1/3Ni1/3Co1/3O2 of lithium-ion battery with dimethyl sulfoxide (DMSO) instead of N-methylpyrrolidone (NMP) on the electrochemical performance of the battery has been investigated for the first time. Observation shows that preparing the cathode active materials with dimethyl sulfoxide will increase the conductivity of the battery. The results show that the as-recovered LiMn1/3Ni1/3Co1/3O2 modified with LiOH · H2O calcined at 450°C delivers discharge capacities of about 247 mA h g−1 in the first cycle with discharge efficiency of 83.1% in sample doped with dimethyl sulfoxide, and 189 mA h g−1 with discharge efficiency of 82.7% in N-methylpyrrolidone at the rate of 0.2 C. The asrecovered samples calcined at 800 and 850°C deliver 149 and 217 mA h g−1 in the fourth cycles respectively in dimethyl sulfoxide. The capacity loss observed in dimethyl sulfoxide faded with increase in cycle numbers. In general, for the samples doped with dimethyl sulfoxide, better performances were evident with high discharge capacities in powders calcined at a lower temperature than higher temperature in accordance with particle sizes shown by the SEM images. On the basis of better cyclic performance of lithium metal cathode and environmental safety, it is evident that relatively cheap dimethyl sulfoxide could replace N-methylpyrrolidone in battery formulations. The X-ray diffraction patterns revealed that LiMn1/3Ni1/3Co1/3O2 was successfully recycled by dimethyl sulfoxide.