Rationally regulating P-doping species to realize ultrastable potassium storage of carbon anode

Abstract

Implanted phosphorus (P) atoms can greatly broaden carbon interlayer spacing and boost defect content, thus resulting in increased rate and capacity; however, different P-species (e.g., P-C and P-O) are how to affect interspacing and defect still remains unclear, and needs to be fundamentally explored. Herein, carbon materials with controllable P-C and P-O moieties (denoted as PNC-900-T, T = 0.2, 0.3, and 0.4) are first synthesized via a gas-steaming route. Detailed experimental analyses demonstrate that P-O species are positively correlated with interspacing, while P-C bonds devote more to enhancing defect. Besides, the introduced P-dopants can trigger the evolution of pore architecture from mesopores to micro/mesopores mixing and then to micropores. As such, the PNC-900–0.3 with the highest P-O proportion (74.8%) realizes the largest interspacing (0.377 nm), thus enabling more K-ions insertion and accelerating their migration. And its defect and micropores can function as active sites to promote the adsorption storage of K-ions. All these together contribute to high capacity, rate (232.3 mAh/g at 2 A/g), and a prolonged cycle lifespan (230.2 mAh/g over 2000 cycles). The effects of different P configurations on microstructure identified by this work provide an insight into the synthesis of other P-functionalized carbon.