Non-Aqueous K-Ion Battery Based on Layered K_0.3MnO₂and Hard Carbon/Carbon Black

Herein, we present the synthesis and characterization of negative (a hard carbon/carbon black composite) and positive (K 0.3 MnO 2 ) active materials for K-ion batteries as well as their combination in a non-aqueous K-ion cell. The hard carbon/carbon black composite can deliver up to 200 mAh g −1 while the layered birnessite K 0.3 MnO 2 delivers up to 136 mAh g −1 . The K-ion cell exhibits an interesting and encouraging cycling performance for 100 cycles. These exciting new insights demonstrate the potential of K-ion batteries, which are worth to be further investigated in greater detail.