Pre-Intercalation of Squaric Acid to Construct V-O-C Bonding: Boosting Zn 2+ Storage in H 11 Al 2 V 6 O 23.2 Cathode

Abstract

Preintercalation engineering has been proven to be an effective strategy for alleviating the limitations of vanadium oxide cathode materials. However, single-ion pre-intercalation suffers from issues such as limited structural regulation capability and uneven interlayer electrostatic repulsion. In view of this, this work reports a squaric acid molecule preintercalation engineering to enhance the high-efficiency Zn 2+ storage capability of H 11 Al 2 V 6 O 23.2 (denoted as HAVO-Sq80). The results demonstrate that squaric acid molecules form V-O-C bonds with the material to stabilize the interlayer structure, and the preintercalation engineering expands theinterlayer spacing of the material to 1.46 nm, thus achieving a high specific capacity of ~500 mAh g -1 at 0.2 A g -1 as well as excellent cycling stability, retaining 96.3% of its initial capacity after 7000 cycles at a high current density of 10 A g -1 . The assembled pouch cell (mass: 450 mg, 10.6 mg cm -2 ) delivers a capacity retention rate of 87% after 100 cycles at 0.1 A g -1 .Theoretical calculations reveal that squaric acid molecules enhance the electrical conductivity of the material, optimize the charge distribution after Zn 2+ intercalation, and stabilize the V-O bonds of the material. This squaric acid molecular preintercalation strategy establishes an efficient design paradigm for boosting the performance of vanadium oxides, which is expected to break the bottleneck in the development of highperformance cathode materials for aqueous zinc-ion batteries (AZIBs).