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US-12626958-B2 - Zinc-iodine battery

US12626958B2US 12626958 B2US12626958 B2US 12626958B2US-12626958-B2

Abstract

An aqueous rechargeable zinc-iodine battery includes an aqueous electrolyte solution including zinc-iodine; a zinc anode; and a double-layered cathode having: a conductive substrate, and an adsorptive layer disposed over the conductive substrate.

Inventors

  • Yat Li
  • Dun Lin

Assignees

  • THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Dates

Publication Date
20260512
Application Date
20220414

Claims (9)

  1. 1 . A cathode for a zinc-iodine redox flow battery including an aqueous electrolyte solution of zinc iodide, the cathode comprising: a first layer comprising a two-dimensional carbon structure triiodide ions, wherein the triiodide ions are generated when the cathode contacts the aqueous electrolyte solution of zinc iodide; and a second layer disposed on and in contact with the first layer, the second layer comprising an electrically-conductive polymer film including at least one of polypyrrole or poly(3,4-ethylenedioxythiophene), wherein the second layer adsorbs the generated triiodide ions, such that the triiodide ions are reduced at an interface between the first layer and the second layer.
  2. 2 . The cathode according to claim 1 , wherein the two-dimensional carbon structure is one of a carbon fiber cloth or graphene.
  3. 3 . The cathode according to claim 1 , wherein the second layer includes the polymer film deposited on a second conductive material, which is a two-dimensional carbon structure.
  4. 4 . The cathode according to claim 3 , wherein the polymer film is electro-polymerized onto the second conductive material.
  5. 5 . The cathode according to claim 4 , wherein electro-polymerization of the polymer film is carried out in about 10 cycles to about 300 cycles.
  6. 6 . The cathode according to claim 4 , wherein the polymer film is deposited at a concentration from about 1.00 mg/cm 2 to about 10.00 mg/cm 2 .
  7. 7 . The cathode according to claim 6 , wherein the polymer film is deposited at a concentration of about 1.48 mg/cm 2 , 2.88 mg/cm 2 , 5.23 mg/cm 2 , or 9.56 mg/cm 2 .
  8. 8 . A battery comprising the cathode of claim 1 and a zinc anode.
  9. 9 . The battery according to claim 8 , further comprising an aqueous electrolyte solution including iodine.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application claims the benefit of and priority to U.S. Provisional Application No. 63/174,638, filed on Apr. 14, 2021. The entire disclosure of the foregoing application is incorporated by reference herein. GOVERNMENT LICENSE RIGHTS This invention was made with Government support under Grant No. NNX15AQ01, awarded by Merced Nanomaterials Center for Energy and Sensing (MACES), a NASA funded MIRO center. The Government has certain rights in the invention. BACKGROUND Aqueous rechargeable zinc-based batteries (ARZBs) are promising candidates for next-generation grid storage and battery-buffered charging stations due to their high level of safety, low-cost, high-power density, and many other advantages. Researchers have developed various ARZBs, including Zn-ion batteries, alkaline Zn-based batteries, Zn-based redox flow batteries, etc. These include the zinc-iodine (Zn—I2) redox flow battery which uses a ZnI2 aqueous solution as an electrolyte and has attracted much attention. This battery offers impressive theoretical capacity (211 mAh giodine−1, 820 mAh gzinc−1) and energy density (322 Wh L−1) owing to the high solubility of ZnI2 (up to 7 M) and multi-electron conversion reactions during charge/discharge. During charging, metallic zinc is electrodeposited on the anode (Zn2++2e−→Zn), while the slightly soluble iodine is generated on the cathode and spontaneously transformed into highly soluble triiodide (I3−) ions with the presence of iodide (I−) ions (2I−→I2+2e−; I2+I−→I3−). The reverse reactions occur during discharging. In recent years, static Zn—I2 batteries (ZIBs) have been developed to overcome critical intrinsic drawbacks of flow batteries, such as bulky, complex cell configuration and low overall energy density due to the need for supporting equipment. However, a major challenge for both static and flow ZIBs is the self-discharge caused by the shuttling of I3− ions to the zinc anode, which can potentially cause low Coulombic efficiency (CE). A common strategy to address this issue is to physically block the I3− shuttling by using an ion selective membrane (ISM) as a separator (e.g., anion exchange membranes such as Nafion). However, the incorporation of ISMs substantially increases the device cost and inner resistance. One option that avoids using expensive ISMs involves encapsulating I2 in microporous carbon and using a non-ZnI2 solution as the electrolyte. In such cases, I2/I− conversion reactions are confined inside micropores, while the generation and shuttling of I3+ do not occur due to the absence of I− in the aqueous electrolyte (e.g., ZnSO4). Although this model results in high CE, the device's total capacity and energy density are compromised because of the limited I2 loading in the microporous carbon. Other batteries utilize a water-in-salt electrolyte to achieve surface heterogeneous (I2/I−) conversion reactions without the need for ISMs. Despite the greatly enhanced CE, the highly concentrated electrolyte had high viscosity and low conductivity, limiting the highest charge/discharge rate to 300 μA cm−2. Thus, this is not favorable for practical high-power applications. Therefore, there is a need for static Zn—I2 battery that retains a high CE in aqueous ZnI2 electrolyte without the use of ISMs or other similarly expensive components. SUMMARY Aqueous rechargeable zinc-iodine batteries (ZIBs) are considered as promising candidates for grid energy storage due to their high energy density, low cost, and good safety. However, shuttling of highly soluble triiodide ions (I3−) to the anode lowers the Coulombic efficiency (CE), which hinders the commercialization of such batteries. The present disclosure provides a ZIB having a double-layered cathode that includes a conductive layer (CL) coupled to an adsorptive layer (AL). This cathode structure enables the formation and reduction of adsorbed I3— ions at the conductive layer/adsorptive layer interface, thereby suppressing shuttling of the I3− ions. A prototypical ZIB may use carbon cloth as the conductive layer and carbon-cloth-loaded polypyrrole (PPy) as the adsorptive layer simultaneously achieves outstanding Coulombic efficiency (up to 95.6%) and voltage efficiency (up to 91.3%) in aqueous ZnI2 electrolyte even at high-rate intermittent charging/discharging, without the need of ion selective membranes. The double-layered cathode according to the present disclosure may be incorporated into design and fabrication of practical ZIBs and other batteries based on conversion reactions. As used herein, the term “about” denotes a range of ±5% of the stated value. According to one embodiment of the present disclosure, a cathode for a zinc-iodine redox flow battery is disclosed. The cathode includes a first layer formed from a conductive material, and a second layer in contact with the first layer, where the second layer adsorbs a triiodide ion and where the triiodide ion is reduced at an interface between