Aqueous cerium ion battery: A novel aqueous rechargeable battery

Abstract

Aqueous rechargeable batteries (ARBs) are a potential energy storage system with lowcost aqueous electrolyte and high safety. Multivalent host carriers in electrolyte can offer a wider variety of valence states and redox properties leading to high capacity. In this work, an aqueous cerium ion aqueous (ACIBs) battery has been reported with a satisfactory electrochemical performance for the first time. By utilizing the advantages of stable structure and three-dimensional (3D) open framework of Prussian blue analogues (PBAs), the problem of cerium ions insertion/de-insertion into host materials due to high charge and large size can been successfully solved. Herein, the copper hexacyanoferrate (CuPBA) is prepared through a facile coprecipitation strategy as cathode material of ACIBs. The CuPBA cathode deliver a satisfactory capacity (79 mAh g−1 at 50 mA g−1) and an excellent cycling stability after long-time cycles (86.8 % capacity retention after 5000 cycles at 1000 mA g−1). As a result, the cathode material in ACIBs system displays excellent rate capability and cycling performance. The successful assemble of the full battery also verifies the feasibility of ACIBs. In addition, the energy storage mechanism of Ce3+ ion insertion/de-insertion process is explained by ex situ X-ray diffraction and X-ray photoelectron spectroscopy measurements. This work opens up a new direction and provides a foundation for development of novel ARBs.