Constructing pore arrays on nitrogen-doped carbon to boost potassium-ion storage capacity

Abstract

The structural design of porous carbon materials is a research hotspot in potassium-ion batteries. More often than not, the pores are randomly distributed without intentional size regulation. In this work, we tried to construct well-defined pore arrays on nitrogen-doped carbon materials through an acid-etching procedure. In this strategy, strong acid attacked metal-oxide laden carbonous materials, leaving only carbon skeletons. The final aperture and pore alignment depended exclusively on the size and distribution of pristine metal oxides in carbon matrix. After electrochemical tests, it was found that porous carbon materials would experience an evolution process to achieve optimal pore configuration that was beneficial to the promotion of K+-storage capacity. This process was highly relevant to the initial pore configuration of carbon materials. The more ordered pore alignment and smaller aperture, the quicker pore evolution and better cycle/rate performance (e.g. 300.6 mAh g−1 at 0.1 A g−1 after 500 cycles and 218.1 mAh g−1 at 5 A g−1).