Greatly Enhanced Faradic Capacities of 3D Porous Mn3O4/G Composites as Lithium-Ion Anodes and Supercapacitors by C–O–Mn Bonding

Through C–O–Mn bonding, graphene nanosheets are homogeneously dispersed in porous Mn3O4 to take full advantages of porous Mn3O4 and graphene nanosheets, making the as-formed three-dimensional porous Mn3O4/reduced graphene oxide (rGO) composite exhibit good electrochemical performance. Besides, C–O–Mn bonding is demonstrated to greatly promote the Faradic reactions of the composite, resulting in the enhancement of its real capacity in supercapacitor (SC) electrodes as well as lithium-ion battery (LIB) anodes. By simply fine-tuning the content of graphene (<7 wt %), the composite with 2.8 wt % of rGO delivers a high capacitance of 315 F g–1 at 0.5 A g–1 with a high rate capability of 64.7% at 30 A g–1 and an excellent cycling stability of 105% (5 A g–1, 5000 cycles) as an SC electrode. Also, the one with 6.9 wt % rGO can present a reversible capacity of more than 1500 mAh g–1 at 0.05 A g–1 as the LIB anode, the highest value reported to date, which remains 561 mAh g–1 at 1 A g–1.