Advanced Pre-Diagnosis Method of Biomass Intermediates Toward High Energy Dual-Carbon Potassium-Ion Capacitor

Potassium ion capacitors (PICs) have the potential to combine the advantages of capacitors and batteries, making them promising energy storage substitutes for existing systems. Biomass-based-electrodes are very promising materials for potassium storage, however, at present, the acquisition of biomass-based-electrodes is mainly dependent on high temperature calcination, which makes the efficient utilization of biomass materials quite challenging. Herein, in accordance with ex-situ C-13 NMR and Raman, a universally directional selection strategy of biomass precursors through an advanced pre-diagnosis method for calcination intermediates and a sulfur engineering strategy are initially proposed, proving that the carbon materials derived from precursors with fewer aliphatic chains and more aromatic carbons show a higher yield and can be have more K ions inserted. In addition, the evolution mechanism of in-plane/interlayered C-S bonds is thoroughly evaluated. Notably, PICs assembled by such carbon materials as the battery-type anode, deliver a high energy density of 151 Wh kg(-1) and an ultrahigh power output of 10 kW kg(-1), closing to state-of-the-art values for PICs. This breakthrough opens up a new avenue for targeted design of biomass materials and offers in-depth insights into the evolution of S-C bonds, promoting the energy/power density of PICs devices to a higher level.