Non-aqueous calcium-based dual-ion batteries with an organic electrode of high-rate performance

Calcium-based batteries are considered a promising candidate for the sustainable energy storage system of the next generation because of the abundance of Ca. However, the development of Ca-based batteries is hindered by the incompatibility between metallic Ca and common electrolytes as well as the absence of calcium-ion-hosted materials with good performance and cycling stability. Herein, we firstly investigate a small molecular organic material, 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), as the calcium-ion host for calcium-ion batteries (CIBs) in the non-aqueous electrolyte. Spectroscopic, structural, and computational studies reveal that PTCDI with an enhanced Ca2+-storage degree can increase the solubility of reduced PTCDI due to the reduced π-π interaction, suppressed by the saturated electrolyte owing to the high redeposition rate to form a PTCDI film with strengthened hydrogen bonds, which facilitates a fast enolization reaction for Ca2+ storage. A cell assembled with the PTCDI negative electrode and carbon-based positive electrode exhibits a high-power density >3000 W kg−1, a high energy density of ∼150 Wh kg−1, and superior reversible capacity of 80 mAh g−1 at 5 A g−1. The assembled CIB even demonstrates the high-rate performance (90 mAh g−1 at 1 A g−1) and ultra-stable cyclability over 4000 cycles with negligible decay at -10 °C, suggesting the promising future as low-temperature batteries.