Enhancing the kinetics of vanadium oxides via conducting polymer and metal ions co-intercalation for high-performance aqueous zinc-ions batteries

A Feasible Strategy for High-Performance Aqueous Zinc-Ion Batteries: Introducing Conducting Polymer

Aqueous zinc ion batteries (AZIBs) offer great potential for large-scale energy storage because of their high safety, low cost and acceptable energy density. However, the cycle life of AZIBs is inevitably affected by parasitic reactions and dendritic growth caused by multiple factors such as electrode, electrolyte and separator, which pose significant obstacles to the practical application of AZIBs. To address these challenges, conducting polymer (CP) based materials have gained widespread attention in the realm of rechargeable batteries due to the adjustable band gap, controllable morphology, and excellent flexibility of CPs. In particular, CPs exhibit remarkable conductivity, low dimensionality, and doping characteristics, making them highly promising for integration into the AZIB system. In this review, the problems associated with the cathode, anode, electrolyte, and separator of AZIBs are discussed, and the application of CPs for their modification is summarized. The review provides a comprehensive analysis of the action mechanisms involved in the CP modification process and offers valuable insights for the design and development of CPs that can be effectively utilized in AZIBs. Additionally, the review presents a promising outlook of this research field, aiming to further advance the application of low-cost and high-performance CPs and their composites in AZIBs.

Engineering Interlayer Space and Composite of Square-Shaped V2O5 by PVP-Assisted Polyaniline Intercalation and Graphene for Aqueous Zinc-Ion Batteries

V2O5 undergoes irreversible phase transition and collapse of layered structure during the Zn2+ insertion/extraction, which severely limits its application as a cathode for aqueous zinc-ion batteries (AZIBs). Herein, a synergistic strategy of conductive polyaniline insertion and graphene composite was proposed to boost the Zn2+ storage performance of the V2O5 cathode. A square-shaped polyaniline (PANI)-intercalated and graphene-composited vanadium oxide (GO/PANI-PVP/V2O5) structure was successfully synthesized via an in situ oxidation/insertion polymerization combined with a hydrothermal method. The results showed that PANI intercalation and the composite of graphene combined with layered V2O5, enabling reversible intercalation of Zn2+/H+. The insertion of conjugated PANI not only increases the lattice spacing of V2O5, providing a channel for rapid transport of Zn2+, but also increases the storage sites for charges through doping/dedoping processes and redox conversion reactions. GO/PANI-PVP/V2O5 delivers an excellent specific capacity (495 mA h g-1 at 0.1 A g-1), wonderful rate capability (208 mA h g-1 at 30 A g-1), and good cycling stability (93% after 4000 cycles). Our results provide a new approach for adjusting the valence states, interlayer spacing, and rational design of organic-inorganic compound materials for different functional materials.

High Performance Aqueous Zinc-Ion Batteries Developed by PANI Intercalation Strategy and Separator Engineering

Aqueous zinc-ion batteries (ZIBs) have attracted burgeoning attention and emerged as prospective alternatives for scalable energy storage applications due to their unique merits such as high volumetric capacity, low cost, environmentally friendly, and reliable safety. Nevertheless, current ZIBs still suffer from some thorny issues, including low intrinsic electron conductivity, poor reversibility, zinc anode dendrites, and side reactions. Herein, conductive polyaniline (PANI) is intercalated as a pillar into the hydrated V2O5 (PAVO) to stabilize the structure of the cathode material. Meanwhile, graphene oxide (GO) was modified onto the glass fiber (GF) membrane through simple electrospinning and laser reduction methods to inhibit dendrite growth. As a result, the prepared cells present excellent electrochemical performance with enhanced specific capacity (362 mAh g-1 at 0.1 A g-1), significant rate capability (280 mAh g-1 at 10 A g-1), and admirable cycling stability (74% capacity retention after 4800 cycles at 5 A g-1). These findings provide key insights into the development of high-performance zinc-ion batteries.

The Compatibility of COFs Cathode and Optimized Electrolyte for Ultra-Long Lifetime Rechargeable Aqueous Zinc-Ion Battery

Rechargeable aqueous zinc-ion batteries (RAZIBs) are attractive due to their affordability, safety, and eco-friendliness. However, their potential is limited by the lack of high-capacity cathodes and compatible electrolytes needed for reliable performance. Herein, we have presented a compatibility strategy for the development of a durable and long-lasting RAZIBs. The covalent organic frameworks (COFs) based on anthraquinone (DAAQ-COF) is created and utilized as the cathode, with zinc metal serving as the anode. The electrolyte is made up of an aqueous solution containing zinc salts at various concentrations. The COF cathode has been designed to be endowed with a rich array of redox-active groups, enhancing its electrochemical properties. Meanwhile, the electrolyte is formulated using triflate anions, which have exhibited superiority over sulfate anions. This strategy lead to the development of an optimized COF cathode with fast charging capability, high Coulombic efficiency (nearly 100 %) and long-term cyclability (retention rate of nearly 100 % at 1 A g-1 after 10000 cycles). Moreover, through experimental analysis, a co-insertion mechanism involving Zn2+ and H+ in this cathode is discovered for the first time. These findings represent a promising path for the advancement of organic cathode materials in high-performance and sustainable RAZIBs.

Boosting zinc-ion storage performance by interlayer chemistry modulation on an organic-inorganic hybrid cathode

Aqueous zinc-ion batteries (AZIBs) have triggered a surge of scientific research due to the unique merits of high safety, volumetric specific capacity, and environmental benignity. However, the implementation of this technology is still plagued by the lack of high-performance cathodes that can output high energy density and exceptional cycle life and inadequate Zn reversibility. Here, an organic-inorganic hybrid cathode based on a poly(3,4-ethylenedioxythiophene) (PEDOT) intercalated hydrated vanadium oxide (denoted PVO), which delivers an ultrahigh discharge capacity of 513.1 mAh g-1 (0.5 A g-1) and an ultra-stable cycle with 95.3 % capacity retention and approximately 100 % Coulombic efficiency over 2000 cycles (20 A g-1), is developed. Combining substantive measurements and theoretical calculations, it is demonstrated that favorable structural features with expanded interlayer galleries and robust architecture are believed to be responsible for the enhanced electrochemical performance, which can be further boosted by the improved Zn reversibility because of the introduction of maltitol electrolyte additive. This work provides a new attempt to achieve organic-inorganic composites for high-performance cathode materials of AZIBs and new insights into the charge storage behavior under the synergistic regulation of bilateral interfaces.

Ni-doped Bi2O2CO3 nanosheet with H+/Zn2+ co-insertion for "rocking chair" zinc-ion battery

Developing insertion-type anode is key to advancing "rocking chair" zinc-ion batteries, though there are few reported insertion-type anodes. Herein, the Bi₂O₂CO₃ is a high-potential anode, with a special layered structure. A one-step hydrothermal method was used to prepare Ni-doped Bi₂O₂CO₃ nanosheet, and also a free-standing electrode consisting of Ni-Bi₂O₂CO₃ and CNTs was designed. Both cross-linked CNTs conductive networks and Ni doping improve charge transfer. Ex situ tests (XRD, XPS, TEM, etc.) reveal the H⁺/Zn²⁺ co-insertion mechanism of Bi₂O₂CO₃ and that Ni doping improves its electrochemical reversibility and structural stability. Therefore, this optimized electrode offers a high specific capacity of 159 mAh g^-1 at 100 mA g^-1, a suitable average discharge voltage of ≈0.400 V, and a long-term cycling stability of 2200 cycles at 700 mA g^-1. Besides, the Ni-Bi₂O₂CO₃//MnO₂ "rocking chair" zinc-ion battery (based on the total mass of cathode and anode) delivers a high capacity of ≈100 mAh g^-1 at 50.0 mA g^-1. This work provides a reference for designing high-performance anode in zinc-ion batteries.

Polyaniline functionalized separator as synergistic medium for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have received increasing attention as a promising energy storage device. However, it was rarely reported that the separators as a synergistic medium stabilize the cathode and anode materials. Herein, a polyaniline functionalized glass fiber separator (PANI-GF) was synthesized in situ. The porous structure of PANI effectively regulated the flux of zinc ions inside the separator and its deposition behavior through ion confinement. The abundant N-containing functional groups can adsorb water molecules and effectively reduce harmful side reactions. Moreover, the PANI-GF separator adjusted pH to inhibit dissolution of the cathode by protonation. Importantly, based on the synergistic separator, the Zn-MnO₂ full cell exhibited more than twice discharge capacity compared to the conventional cell after 1000 cycles at 2 A g^-1. This study provided in-depth insight into the design of convenient, reliable, cost-effective, and synergistic separators for AZIBs.

Synergistic zinc-ion storage enabled by Cu ion in anthraquinone-preinserted vanadate: structural integrity and H+-promoted reversible phase conversion

Oxygen-deficient anthraquinone (2-M-AQ)-intercalated vanadium oxide shows an outstanding long lifespan in electrolyte with Cu2+ due to the dual-pillar of 2-M-AQ/Cu2+ and H+-promoted reversible phase conversion.