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

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 g(−1) at 100 mA g(−1) and a high reversible specific capacity of 330 mA h g(−1) with 120% specific capacity retention after 2,000 cycles at 2,000 mA g(−1), 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 g(−1), 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.