Potassium-Based Dual Ion Battery with Dual-Graphite Electrode.

A potassium ion battery has potential applications for large scale electric energy storage systems due to the abundance and low cost of potassium resources. Dual graphite batteries, with graphite as both anode and cathode, eliminate the use of transition metal compounds and greatly lower the overall cost. Herein, combining the merits of the potassium ion battery and dual graphite battery, a potassium-based dual ion battery with dual-graphite electrode is developed. It delivers a reversible capacity of 62 mA h g-1 and medium discharge voltage of ≈3.96 V. The intercalation/deintercalation mechanism of K+ and PF6- into/from graphite is proposed and discussed in detail, with various characterizations to support.