In-situ bonding with sulfur in petroleum asphalt to synthesize transition metal (Mn, Mo, Fe, or Co)-based/carbon composites for superior lithium storage

Abstract Nowadays, rational yet high value-added utilization of low-cost petroleum asphalt still faces a significant challenge. In light of its high carbon content and abundant sulfur atoms, here, an in-situ bonding sulfur strategy is proposed to fabricate transition metal (Mn, Mo, Fe, or Co)-based/carbon composites (TM-based/C). This strategy successfully achieves the conversion from thiophenic-S of asphalt into transition metal sulfides (TMSs). When tested as anodes for lithium-ion batteries (LIBs), the TM-based/C electrodes deliver better specific capacity and cycling performance than those of sulfur-doped carbon nanosheets (SCN) electrode. As a typical example, a 3D network-nanosheets structure of Mn-based/C composite is constructed, and the optimized MnO2/MnS2/C-2 electrode achieves low charging/discharging voltage platform of 1.2 V/0.58 V, and delivers long-term life of 827 mAh g−1 after 400th cycle at 0.5 A g−1. These excellent electrochemical properties benefit from its structural integrity upon cycling and the formation of MnS2/MnO2 phases. Furthermore, LiFePO4/(MnO2/MnS2/C-2) full cell exhibits a remarkably reversible capacity of 168 mAh g−1 at 0.8C, and impressive cycling stability of 78% after 400 cycles at 1 C, better than those of LiFePO4/(commercial graphite). This work may provide a new perspective for the high value-added utilization of low-cost petroleum asphalt for efficient anodes toward LIBs.