Converting biomass waste into microporous carbon with simultaneously high surface area and carbon purity as advanced electrochemical energy storage materials

Developing carbon materials featuring both high accessible surface area and high structure stability are desirable to boost the performance of constructed electrochemical electrodes and devices. Herein, we report a new type of microporous carbon (MPC) derived from biomass waste based on a simple high-temperature chemical activation procedure. The optimized MPC-900 possesses microporous structure, high surface area, partially graphitic structure, and particularly low impurity content, which are critical features for enhancing carbon-based electrochemical process. The constructed MPC-900 symmetric supercapacitor exhibits high performances in commercial organic electrolyte such as widened voltage window up to 3 V and thereby high energy/power densities (50.95 Wh kg ⁻¹ at 0.44 kW kg ⁻¹ ; 25.3 Wh kg ⁻¹ at 21.5 kW kg ⁻¹ ). Furthermore, a simple melt infiltration method has been employed to enclose SnO ₂ nanocrystals onto the carbon matrix of MPC-900 as a high-performance lithium storage material. The obtained SnO ₂ -MPC composite with ultrafine SnO ₂ nanocrystals delivers high capacities (1115 mAh g ⁻¹ at 0.2 A g ⁻¹ ; 402 mAh g ⁻¹ at 10 A g ⁻¹ ) and high-rate cycling lifespan of over 2000 cycles. This work not only develops a microporous carbon with high carbon purity and high surface area, but also provides a general platform for combining electrochemically active materials.