Aqueous Zinc Ion Battery with Potassium Selective Hyper Cross-Linked Dibenzo-18-Crown-6-Ether Membrane

Abstract

Nonselective ion transport across the separator in zinc-iodine flow batteries (ZIFBs) alters concentration gradients, precipitates insoluble iodine, and generates uneven zinc nucleation on the anode surface. Here, we report the synthesis of a K+ ion-selective hyper-cross-linked dibenzo-18-crown-6-ether-containing polymer (HCP) that allows transfer of the K+ ion while avoiding the crossover of electroactive species. The sulfonated HCP was blended with SPEEK in compositions of 5, 10, and 15 %, designated as SHCP1, SHCP2, and SHCP3, respectively. The blending of SHCP results in increases in ion exchange capacity (IEC), water uptake, ionic conductivity, and K+ ion selectivity. The best membrane, SHCP3, showed 7.6 times higher K+ ion selectivity than the neat SPEEK membrane. The galvanostatic charging/discharging over 200 cycles at 20 mA cm-2 current density showed 96 % CE, 88% VE, and 84 % EE for the SHCP3 membrane. It delivered 37.5 Ah L-1 capacity at 20 mA cm-2 current density, whereas Nafion-117 delivered 22 Ah L-1 capacity. The OCV of the cell with SHCP3 membranes remains at 1 V over 20 h. The results suggest that K+ ion selectivity is significantly helping in mitigating dendrite formation and enhancing the stability of the ZIFB battery, thus increasing its potential use.

Resilient and Reversible Phosphotungstic Acid Passivated Zinc Anode

“…The full V 2 O 5 //Zn battery with DMMP-H 2 O hybrid electrolyte exhibits a high capacity retention of 82.2% following 4000 cycles at 5 Ag 1− . 3 Similarly, when coated with a zeolite, the anode maintained a smooth, dendrite-free surface even after 1600 charge/discharge cycles, retaining 97% of its initial capacity. 36 In contrast, the commercial Zn plate anode displayed dendritic and overgrown morphologies after 500 cycles, retaining only 69% of its original capacity.…”

“…3 Additionally, ARZBs tend to demonstrate superior power densities compared to their nonaqueous lithium-ion battery counterparts. 2,3 Over the past decade, a variety of rechargeable zinc-based batteries (ARZBs) with diverse catholyte materials and reaction mechanisms have emerged. These include Zn−Fe, 4 Zn−Ce, 5 Zn−Cr, 6 Zn−Br, 7 Zn/Mn, 8 and Zn−I.…”

“…2 Zinc exhibits an energy density ranging from 300 to 450 Wh kg −1 and a theoretical capacity of 820 mAh g −1 Zn . 3 Additionally, ARZBs tend to demonstrate superior power densities compared to their nonaqueous lithium-ion battery counterparts. 2,3 Over the past decade, a variety of rechargeable zinc-based batteries (ARZBs) with diverse catholyte materials and reaction mechanisms have emerged.…”

“…It is due to the abundance of zinc metal, its nontoxic nature, and the use of nonflammable aqueous electrolytes with favorable reaction kinetics . Zinc exhibits an energy density ranging from 300 to 450 Wh kg –1 and a theoretical capacity of 820 mAh g –1 Zn . Additionally, ARZBs tend to demonstrate superior power densities compared to their nonaqueous lithium-ion battery counterparts. , …”

“…Zinc exhibits an energy density ranging from 300 to 450 Wh kg –1 and a theoretical capacity of 820 mAh g –1 Zn . Additionally, ARZBs tend to demonstrate superior power densities compared to their nonaqueous lithium-ion battery counterparts. , …”