Phosphate-Based Cathode Frameworks for Potassium-Ion Battery

Abstract

Lithium-ion battery has remained as the dominant energy storage system due to its high energy density and electrochemical reversibility for the last few decades, albeit its cost and resource restrictions remain prohibitive for largescale applications. With this imminent concern, a great deal of attention has been devoted recently to the development of lower cost and more abundant alternative chemistries such as potassium-ion battery (PIB) [1]. Intensive research on a number of potentially economical potassium-containing host materials as cathode materials for PIB have been reported recently, but most of the potassium-based materials are still not able to meet industrial standards. This mainly stems from the structural instability posed during the electrochemical extraction of the large potassium ion, and also the electrochemical inactivity of some of the host materials. Therefore, at this juncture, it is necessary to identify potassium-containing host materials that can reversibly (de)insert potassium. During the course of our investigation, we have identified K-rich phosphate-based cathode frameworks that can facilitate reversible (de)insertion of potassium-ion. In this presentation, we will briefly introduce our current research progresses on phosphate-based polyanion cathode materials (such as K x MP 2 O 7 pyrophosphates (some of the phases of which are shown in Fig. 1), K x MPO 4 F fluorophosphates and K x MPO 4 monophosphates ( x =1,2)) and provide preliminary results about their electrochemical activity. Reference s : [1] A. Eftekhari, J. Power Sources, 126 (2004) 221-228. Figure 1