One-pot Synthesis and Application in Asymmetric Supercapacitors of Mn$lt;inf$gt;3$lt;/inf$gt;O$lt;inf$gt;4$lt;/inf$gt;@RGO Nanocomposites

Supercapacitors have attracted dramatic attentions in recent years for their apparent advantages, such as fast charge/discharge rate, high power density and high stability. However, it is still a challenge to improve their energy density for their practical applications. One of the strategies to overcome this drawback is to broaden the working voltage of the devices through assembling asymmetric supercapacitors. Herein, Mn 3 O 4 @RGO nanocomposites were successfully synthesized by using one-pot approach with Mn(Ac) 2 and GO in the mixed solvent of ethanolamine and water (3:1) without adding any surfactant. The asymmetric supercapacitors (Mn 3 O 4 @RGO//RGO) assembled with Mn 3 O 4 @RGO and RGO exhibit excellent performances in energy storage. The asymmetric supercapacitors can achieve a maximum energy density of 21.7 Wh/kg at power density of 500 W/kg and a maximum power density of 8 kW/kg at energy density of 11.1 Wh/kg, based on the total mass of active materials. The Mn 3 O 4 @RGO//RGO supercapacitors also demonstrated excellent durability retaining 88.4% of their specific capacitances even after 5000 charge/discharge cycles. The excellent performances of Mn 3 O 4 @RGO//RGO devices in energy storage can be attributed to high density of Mn 3 O 4 nanoparticles grown directly on the surfaces of RGO nanosheets, which can dramatically improve the conductivity of materials.