MgO-template synthesis of hollow N/O dual-doped carbon boxes as extremely stable anodes for potassium-ion batteries

H-NOCBs exhibit superior cycling stability with the retained capacities of 178.8 mA h g −1 (500 mA g −1 ) and 123.3 mA h g −1 (1000 mA g −1 ) after 2500 and 10 000 cycles, respectively, demonstrating extremely stable performance for potassium ion storage.