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

SignificanceThe present work might be significant for exploring advanced K-ion batteries with superb rate capability and cycle stability toward practical applications. 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 the best among those based on carbon materials. The as-constructed full cell delivers 98% specific capacity retention over 750 cycles at 500 mA g -1 , superior to most of those based on carbon materials that have been reported thus far.