A new research perspective: The application of potassiated alloy/carbon composite counter electrode in fundamental and practical research of K-ion batteries

Many efforts were made to modify cathode materials for K-ion batteries to improve their performance. However, the improvements are not so significant. Herein, we show that the performance of host materials are limited by metal K counter electrode, which leads to underestimation of materials. With a potassiated alloy/carbon composite counter electrode, the Prussian blue analogue cathode can show outstanding rate capability at 5000 mA g(-1) and operate 1000 cycles without capacity fading. Besides, when the anode utilization increased to 72.7%, the battery parameters, such as lifespan, energy and power density, were also promising. This work offers a new perspective for both fundamental and practical research of K-ion batteries. (C) 2021 Elsevier Ltd. All rights reserved.