Defective engineering and heteroatom doping construction in carbon nanobowls for achieving high-rate potassium-ion storage with long cyclic life

•K+ adsorbability increases in order of N-doping, O-doping, and vacancy defects.•Heteroatom doping and vacancy defects induce the spontaneous K+ migration.•Abundant N, O-dopants functionalize carbon surface and increase K+ adsorption sites.•K+ storage mechanism was demonstrated via in situ and ex situ techniques in depth.