High-power graphene supercapacitors for the effective storage of regenerative energy during the braking and deceleration process in electric vehicles

Supercapacitors (SCs), with maximal power densities, low self-discharge and wide temperature tolerance, are expected to be ideal electrochemical energy storage (EES) systems for electric vehicles (EVs). Herein, we demonstrated the superior performance metrics of a graphene based SC and its applicability as an advanced EES system for EVs. The 3.0 V graphene SC developed herein possesses a device capacitance of 35.96 F g(-1), energy density of 44.95 W h kg(-1), power density of 18 750 W kg(-1), long cycle life and wide temperature operation (-15 to 80 degrees C). The role of ohmic leakage, diffusion-mediated charge-redistribution and over-charging issues on the self-discharge mechanism of the graphene SC are studied. The effects of temperature on the capacitive properties of the graphene SC are studied using complex capacitance models. Additionally, the use of a graphene SC as the primary EES system to store regenerative energy during braking/deceleration modes and as an auxiliary power source (in combination with a battery) to drive EVs is also demonstrated. These studies highlight the potential applicability of a graphene SC as an ideal EES system for next-generation EVs.

Automated summary

Graphene supercapacitors exhibit superior performance metrics such as high energy density, high power density, long cycle life, and wide temperature range, making them suitable for the electrochemical energy storage system of electric vehicles.