Polyiodide Confinement by Starch Enables Shuttle‐Free Zn–Iodine Batteries

Abstract

large-scale energy-storage systems. [2] Aqueous zinc-based batteries with high safety and low cost provide a new opportunity for energy storage on a large scale. [3] Among the series of zinc-based batteries, the rechargeable zinc-iodine (Zn-I 2 ) battery is promising owing to abundant reserves of iodine in seawater (55 µg L −1 ), [4] high specific capacity (211 mAh g iodine −1), [5] and high discharge potential plateau (1.38 V vs Zn/Zn 2+ ). [6] Besides, the liquid-phase conversion mechanism of I − /I 2 in cathode endows a Zn-I 2 system with excellent rate capability. [7] However, the state-of-the-art Zn-I 2 batteries are still far from satisfactory due to the challenges of intermediates dissolution as well as Zn-anode corrosion. [4a] In aqueous electrolytes, Zn-I 2 batteries present a reversible I − /I 2 redox reaction, in which polyiodide species work as the intermediate state. [7] However, highly soluble polyiodide intermediates cause the serious shuttle effect, leading to irreversible loss of active mass. Even worse, the direct reaction between shuttling polyiodide and Zn anodes will further aggravate serious Zn corrosion and consumption, leading to the low Coulombic efficiency (CE), and limited durability of Zn-I 2 batteries. Therefore, inhibiting the shuttle effect of polyiodide is of great importance to stabilize the I 2 cathode and alleviate the Zn corrosion toward high-cyclability Zn-I 2 batteries. AqueousZn-iodine (Zn-I 2 ) batteries have been regarded as a promising energy-storage system owing to their high energy/power density, safety, and cost-effectiveness. However, the polyiodide shuttling results in serious active mass loss and Zn corrosion, which limits the cycling life of Zn-I 2 batteries. Inspired by the chromogenic reaction between starch and iodine, a structure confinement strategy is proposed to suppress polyiodide shuttling in Zn-I 2 batteries by hiring starch, due to its unique double-helix structure. In situ Raman spectroscopy demonstrates an I 5 − -dominated I − /I 2 conversion mechanism when using starch. The I 5 − presents a much stronger bonding with starch than I 3 − , inhibiting the polyiodide shuttling in Zn-I 2 batteries, which is confirmed by in situ ultraviolet-visible spectra. Consequently, a highly reversible Zn-I 2 battery with high Coulombic efficiency (≈100% at 0.2 A g −1 ) and ultralong cycling stability (>50 000 cycles) is realized. Simultaneously, the Zn corrosion triggered by polyiodide is effectively inhibited owing to the desirable shuttling-suppression by the starch, as evidenced by X-ray photoelectron spectroscopy analysis. This work provides a new understanding of the failure mechanism of Zn-I 2 batteries and proposes a cheap but effective strategy to realize high-cyclability Zn-I 2 batteries.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202201716.

A High-Performance Quasi-Solid-State Aqueous Zinc–Dual Halogen Battery

“…As shown in in situ Raman spectra (Figure S18) and the corresponding color plot (Figure 3c,d), a characteristic peak that emerged at ∼167 cm −1 corresponds to the higher polyiodide (i.e., I 5 − ). 36,37 The intensity of this peak increases during the voltage range of 1.20−1.50 V, confirming the I − /I 0 redox reaction (Figure 3e, bottom panel). When the voltage reaches 1.50 V, the peak begins to shift toward higher frequency, which can be attributed to the generation of [IBr 2 ] − interhalogen (∼180 cm −1 ).…”

“…In situ Raman spectroscopy and XPS were applied to investigate the carbon cloth–iodine cathode cycling in LiNO 3 -containing electrolyte. As shown in in situ Raman spectra (Figure S18) and the corresponding color plot (Figure c,d), a characteristic peak that emerged at ∼167 cm –1 corresponds to the higher polyiodide (i.e., I 5 – ). , The intensity of this peak increases during the voltage range of 1.20–1.50 V, confirming the I – /I 0 redox reaction (Figure e, bottom panel). When the voltage reaches 1.50 V, the peak begins to shift toward higher frequency, which can be attributed to the generation of [IBr 2 ] − interhalogen (∼180 cm –1 ). , In the middle panel of Figure e, such a characteristic peak suggests the co-existence of higher polyiodides and [IBr 2 ] − interhalogen.…”

Development of long lifespan high-energy aqueous organic||iodine rechargeable batteries

“…1a (Supplementary Fig. 16 and Supplementary Note 13 ) 2 , 3 , 5 , 58 . A new strong peak (341 nm) corresponding to the formation of ICl interhalogens was observed when the system was charged to 2.4 V, verifying the conversion of I 0 to I + .…”

Boosting Cathode Activity and Anode Stability of Zn‐S Batteries in Aqueous Media Through Cosolvent‐Catalyst Synergy

“…[14] However, the commonly used nonpolar I 2 catalyst interacts weakly with sulfur, which usually leads to limited improvement. [15] Even worse, the added I 2 catalyst would accelerate the corrosion of zinc metal, further exacerbating the battery performance. [16] Apparently, approaches that depend just on adding catalysts, and/or optimizing zinc electrolyte salts without concerning the compatibility and otherness of the whole system are difficult to realize electrodes reversibility for aqueous ZnÀ S batteries.…”