Nitrogen-rich porous carbon in ultra-high yield derived from activation of biomass waste by a novel eutectic salt for high performance Li-ion capacitors

High performance N-doping porous carbon (NDPC) are ideal electrode materials for Li-ion capacitors (LICs). However, the practical application of NDPC is extremely limited, which is mainly attributed to the typical methods for the scale preparation NDPC are time-consuming, high cost and low yield. Herein, we have developed a new route for high efficient, environment friendly, low cost and high yield fabrication of NDPC, using biomass waste as the carbon source and a novel eutectic salt as the activation agent. After a series of comparative experiments, the application of eutectic salt herein not only reduce the process time and cost, but also obviously enhance the yield, the specific surface area (SSA) and nitrogen-doping content of NDPC sample (labelled as NDPC-0.5). In combination of the rich N-doping level, larger SSA and interconnected porous structure, the NDPC-0.5 sample exhibit an excellent electrochemical performance as both cathode and anode materials for a LIC, with specific discharge capacities of ∼60 and 290 mAh g⁻¹ at a current density of 5 A g⁻¹. The resultant NDPC-0.5//NDPC-0.5 LIC device delivers a high energy density of 116.9 Wh kg⁻¹ at 500 W kg⁻¹, with a capacity retention of 81% after 8000 cycles at 2 A g⁻¹.