In Situ Oxygen-Doped Porous Carbon Nanoribbons with Expanded Interlayer Distance for Enhanced Potassium Ion Storage

Carbon materials have been widely concerned and studied for potassium-ion batteries because of abundant resources and low prices. But, the large radius of potassium ions (1.38 angstrom) restricts its smooth intercalation and deintercalation into the carbon layer, resulting in poor cycling stability and rate performance. Herein, in situ oxygen-doped porous carbon nanoribbons (OPCNBs) have been fabricated by freeze-drying and pyrolysis of the polymer with enlarged interlayer spacing for the first time. Due to the porosity and the enlarged interlayer spacing (0.413 nm) of OPCNB, the potassium ions can be rapidly intercalated into the carbon layer and smoothly extracted and some of the potassium ions are adsorbed on the surface active site stemming from the oxygen-doped group. Further, ex situ TEM showed that the enlarged interlayer spacing was well preserved during repeated cycling. Therefore, OPCNB exhibits excellent long cycle stability (180.5 mAh g-1 at 500 mA g-1 after 1000 cycles) and outstanding rate capability (170 mAh g-1 at 1 A g-1) as a new generation electrode material with development potential for potassium ions.