Aqueous Calcium-Ion Battery Based on a Mesoporous Organic Anode and a Manganite Cathode with Long Cycling Performance.

Aqueous batteries have attracted increasing and extensive attention, owing to their high safety, low cost, and low toxicity. These factors have become increasingly important, given the current focus on the rapid development of green energy technologies. In particular, multivalent-ion batteries are emerging as alternatives to lithium-ion batteries. Unfortunately, magnesium and aluminum ions have high polarization strengths that are unfavorable for electrode materials. In contrast, calcium-ion batteries successfully avoid the problem of high polarization. Herein, an aqueous calcium-ion battery (CIBs) based on mesoporous silica SBA-15 with a two-dimensional hexagonal through-hole structure is reported. The poly(3,4,9,10-perylentetracarboxylic diimide) (PPTCDI) organic material supported on SBA-15 is used as the anode and displays a capacity of 201 mAh g-1 , with a stable cycling performance of 95 % capacity retention after 1500 cycles. SBA-15@PPTCDI‖Ca2 MnO4 aqueous CIBs demonstrate a high energy density of 130.6 Wh kg-1 in the cell voltage range from 0.0 to 1.8 V, with a high capacity and excellent cycling stability. As the anode material, SBA-15@PPTCDI shows special bonding of redox electrons that leads to its highly stable performance, which paves the way for addressing the shortcomings of traditional organic electrode materials. The localization and delocalization of the redox electron offers additional voltage stability, which is another important advantage for practical applications. This study highlights the potential of organic electrode materials for applications in aqueous multivalent-metal-ion batteries.