High-performance K-ion half/full batteries with superb rate capability and cycle stability

Abstract

Currently, a big problem for exploring K-ion half/full batteries is how to bring them with both high specific capacity and long cycling stability simultaneously, in terms of their intrinsically sluggish kinetics of K+ with larger radius than that of Li+, which often causes huge volume change over the electrochemical reaction. Herein, we report the exploration of high-performance K-ion half/full batteries with superb rate capability and cycle stability based on B-doped porous carbons with increased active sites and improved conductivity. The as-assembled K-ion half cell exhibits an excellent rate capability of 428 mA h g21 at 100 mA g21 and a high reversible specific capacity of 330 mA h g21 with 120% specific capacity retention after 2,000 cycles at 2,000 mA g21, which is state of the art among those based on carbon materials. Moreover, the as-constructed full cell delivers 98% specific capacity retention over 750 cycles at 500 mA g21, which is superior to most of the analogs based on carbon materials that have been reported thus far, underscoring their potential applications in advanced energy storage.