Atomic selenium regulating endows three-dimensional N-doped carbon with fast and stable potassium ion storage

Abstract

Three-dimensional honeycomb-like nitrogen-doped carbon skeleton (3DCN) is regarded as highly promising anode candidate for potassium-ion batteries (PIBs) due to its conspicuous merits including stable structural and fast electrolyte penetration, but it still suffers from limited active sites and sluggish insertion kinetics for K+ storage, leading to unsatisfied specific capacity and unstable structure at high rates. Herein, we propose Se atom-activation combined with micro and mesopores-construction strategies in the carbon layer of 3DCN (Se-3DCN) to increase the specific capacity and promote the reaction kinetics meanwhile maintain the structural stability un-compromised, through a simultaneously conducted Se-decoration and carbon-etching process. The Se atoms induce more delocalized electrons around it therefore activate surrounded carbon atoms being capable of storing K+, and increase the electrical conductivity of electrode. The micro and mesopores homogenize the structural stress that resulted from the volume expansion after K+ intercalation, achieving high structural stability. Therefore, the obtained Se-3DCN anode presents satisfying specific capacities and cycling performances at various rates (294.9 mAh/g at 2000 mA g−1 after 10,000 cycles with zero attenuation). In addition, a full cell assembled with Se-3DCN anode and PTCDA cathode exhibits high energy and power density of 166 Wh kg−1 and 1684 W kg−1, respectively.