Synergistic Ion Sieve and Solvation Regulation by Recyclable Clay-Based Electrolyte Membrane for Stable Zn-Iodine Battery

Aqueous zinc–iodine batteries show immense potential in the electrochemical energy storage field due to their intrinsic safety and cost‐effectiveness. However, the rampant dendritic growth and continuous side reactions on the zinc anode, coupled with the shuttling phenomenon of polyiodides, severely affect their cyclic life. In response, this study utilizes a carboxyl‐functionalized metal‐organic framework UiO‐66‐(COOH)2 (UC) to modify commercial glass fiber (GF) to develop a novel ionic selective separator (UC/GF). This separator exhibits cation exchange ability for Zn2+ and polyiodides, thereby simultaneously stabilizing the zinc anode and inhibiting the shuttle effect of polyiodides. Enhanced by the abundant polar carboxyl groups, the UC/GF separator can effectively facilitate Zn2+ ion transport and accelerate the desolvation of hydrated zinc ions by its zincophilicity and hydrophilicity, while significantly hindering the transfer of polyiodides via electrostatic repulsion. Consequently, the Zn|UC/GF|Zn symmetric battery enables a long lifespan of over 3400 h at a current density of 5.0 mA cm−2, while the Zn|UC/GF|I2 exhibits an exceptional discharge capacity of 103.8 mAh g−1 after 35 000 cycles at 10 C with a capacity decay rate of only 0.0013% per cycle. This separator modification strategy that synergistically optimizes anode and cathode performance provides unique insights into the commercialization of zinc–iodine batteries.

Ionic Selective Separator Design Enables Long‐Life Zinc–Iodine Batteries via Synergistic Anode Stabilization and Polyiodide Shuttle Suppression

Yang,

Zhang,

Liu

et al. 2024

Photo‐Assisted Zn‐Iodine Battery via Bifunctional Cathode with Iodine Host and Solar Response Boost

Xu,

Gao,

Dou

et al. 2024

The aqueous photo‐assisted battery is considered an efficient means of converting and storing solar energy in one device. However, identifying a suitable photocathode with excellent iodine capture capabilities for photo‐assisted Zn‐iodine batteries still remains challenging. In this work, bifunctional BiOI is prepared as sole cathode material for a photo‐assisted Zn‐iodine battery while simultaneously realizing an iodine host and solar responsiveness. The as‐presented BiOI with abundant vacancies offers highly reversible photo‐assisted iodine redox reactions. Meanwhile, the dual reaction routes involving vacancy iodine storage and reversible two‐steps iodine redox are confirmed by in/ex situ characterization techniques during the energy storage process. Consequently, the assembled battery exhibits areal capacity of 0.24 mAh cm−2 at 1 mA cm−2 with coulombic efficiency exceeding 96.5%. More impressively, benefiting from the wide visible light absorption of the BiOI cathode, the battery demonstrates a much enhanced specific areal capacity of 0.4 mAh cm−2 at 1 mA cm−2 under sun illumination, representing a remarkable increment of 60% compared to that in the dark environment. This work expands the utility of cathode materials for a photo‐assisted Zn‐iodine battery.

Heterostructure Design of Amorphous Vanadium Oxides@Carbon/Graphene Nanoplates Boosts Improved Capacity, Cycling Stability and High Rate Performance for Zn²⁺ Storage

Wang,

Dai,

Zhang

et al. 2024

As a promising power supplier, flexible aqueous zinc ion batteries (AZIBs) have drawn great attention and been demonstrated potential applications in portable electronic devices, yet their capacity, stability, and rate performance are severely limited by cathode materials. Herein, a spontaneous encapsulation and in situ phase transformation strategy is proposed for the construction of heterostructured amorphous vanadium oxide@carbon/graphene (A‐VOx@C/G) nanoplates as highly stable and efficient cathode materials for Zn2+ storage. In this design, A‐VOx provides abundant active sites with rapid ion diffusion channels and robust tolerance against ion insertion/extraction, while N‐doped carbon encapsulation and interlaced graphene network ensure efficient electron transfer. The mechanisms respectively for phase transformation during electrochemical amorphization and charge storage during cycling are investigated in detail. The as‐prepared A‐VOx@C/G achieves an outstanding electrochemical performance with 429 mAh g−1 at 0.5 A g−1, 73% retained at 20 A g−1 (315 mAh g−1), and excellent stability over 2000 cycles at 20 A g−1 (91% retention). Moreover, quasi‐solid‐state AZIBs assembled from A‐VOx@C/G cathode exhibit high flexibility and can sustain large mechanical deformation without performance degradation. It is believed that this study provides a guideline toward designing high‐performance cathode materials for AZIBs through structure optimization.