N/O co-doped carbon nanocapsule anodes for high rate-performance K-ion batteries

Abstract

Based on our observations made in our previous work that nitrogen (N)/oxygen (O) dual dopant porous hollow carbon nanocapsules (N/O-CNCs) have state-of-the-art lithium storage and sodium storage capabilities, we further studied their potassium storage performance in this study. It was found that for potassium storage, 259 mA h g[Formula: see text] at 0.05 A g[Formula: see text] can be retained up to 100 cycles, and 107 mA h g[Formula: see text] at 1 A g[Formula: see text] can be retained after 100 cycles. Even at 2 A g[Formula: see text], an excellent rate capability of 73.4 mA h g[Formula: see text] in K-ion batteries (KIBs) was delivered. A capacitive charge–storage mechanism dominated the potassium storage of N/O-CNCs at high rates during the potassiation/depotassiation process through kinetics analysis, ensuring a remarkable rate performance.