Aluminum-ion storage reversibility in a novel spinel Al2/3Li1/3Mn2O4 cathode for aqueous rechargeable aluminum batteries

Abstract

• Spinel Al 2/3 Li 1/3 Mn 2 O 4 (ALMO) is explored for a novel cathode material for AABs • ALMO cathode exhibits remarkable cycle stability and rate performance • The Al//ALMO full cell releases an acceptable voltage and a high energy density • Al ion extraction/insertion mechanisms are clarified via ex-situ characterizations Aqueous aluminum batteries (AABs) is a very promising supplementary energy storage device for lithium-ion batteries (LIBs) in large-scale energy storage, but the lack of cathode materials with high energy density and cycle stability greatly limits the development of AABs. Herein, a spinel Al 2/3 Li 1/3 Mn 2 O 4 (ALMO) cathode material has been synthesized via an electrochemical conversion reaction using LiMn 2 O 4 (LMO) as the precursor. The ALMO cathode releases a discharge capacity of 151.8 mA h g −1 under a current density of 100 mA g −1 and a capacity retention of 64.1% over 1000 cycles. The full cell fabricated using the ALMO cathode exhibits a high energy density of 183 W h kg −1 and an average operating voltage of about 1.31 V, demonstrating a promising device for large-scale energy storage. The Al ion storage mechanism of the ALMO cathode material is scrutinized by a series of ex-situ analysis techniques, indicating the Al 3+ ions can reversibly extract/insert out/into the ALMO cathode material with the oxidation/reduction of Mn. This work is expected to boost the development of the cathode materials for the low-cost and high-performance AABs.