Aqueous Batteries Research Articles

Interlayer engineering of V2O5·nH2O by conductive Ni-BTA enabling high-performance aqueous ammonium ion batteries

Aqueous ammonium ion batteries (AAIBs) are of interest due to the low molar mass, small hydration radius, abundant raw materials and high safety of the carrier ammonium-ion. Nevertheless, there are numerous constraints associated with electrode materials that are suitable for ammonium-ion storage. In this study, we design and synthesize a composite comprising of one-dimensional conductive metal-organic skeleton material (1D c-MOF) embedded between layers of hydrated vanadium pentoxide (VOH) with improved ammonium-ion storage. The central ion of the 1D c-MOF is selected to be the nickel ion, while the ligand is 1,2,4,5-benzenetetramine (BTA). The incorporation of Ni-BTA between the vanadium oxide layers results in the formation of a composite (Ni-BTA/VOH) exhibiting enhanced structural stability, augmented layer spacing and elevated conductivity. Furthermore, the dual energy storage mechanisms of VOH and CN rearrangement act in concert to yield a “1+1 > 2” effect, thereby markedly enhancing the ammonium-ion storage. The specific capacity of Ni-BTA/VOH can reach 183 mAh g−1 at 0.2 A g−1, and the retention rate can reach 52.5 % after 500 cycles at 2 A g−1. This work not only proves the potential of Ni-BTA/VOH for widespread application in the field of aqueous batteries, but also provides a new method for structural engineering of VOH with boosted ammonium-ion storage properties.

In-situ synthesis AgO/AgNPs composite as binder-free cathode for high-performance aqueous AgO-Al batteries

Aqueous AgO-Al batteries are promising systems due to their ultrahigh specific capacity, energy density, and stable output voltage. However, they still suffer from the low utilization and sluggish kinetics of the cathode. In this study, the binder-free AgO/AgNPs composites were synthesized in-situ using a simple electrodeposition method. Due to the excellent conductivity and rich mesoporous structure of AgO/AgNPs materials, the electron and ion transfer kinetics were enhanced, thereby improving the charge storage performance of the electrode. As expected, the AgO-Al battery with the optimized AgO/AgNPs composite cathode demonstrated excellent rate performance, achieving a high discharge capacity of 325.1 mAh g−1, and a stable operating voltage platform of 1.55 V at the current density of 1000 mA cm−2. The maximum energy and power density were 687 Wh kg−1 and 6.2 kW kg−1, respectively. This work presents an effective strategy for designing high-performance AgO electrode materials for AgO-Al batteries.

Zinc hexacyanoferrate with open framework for efficient aqueous cobalt ions storage

In this work, we report a high-performance aqueous Co-ion battery with zinc hexacyanoferrate as Co2+ storage material. Owing to the open framework, zinc hexacyanoferrate exhibits excellent electrochemical performance. The reversible capacity of zinc hexacyanoferrate is up to 62.4 mAh g−1 at 5C with ultralow capacity decay (0.0084 % per cycle) within 500 cycles. Even cycled at a higher rate of 10C, zinc hexacyanoferrate still can remain a high capacity retention of 98.8 % after 700 cycles. The excellent electrochemical performance is attributed to the rapid kinetics behavior of Co2+ in the open and stable framework structure. Besides, a joint analysis of in-situ X-ray diffraction, ex-situ Fourier transform infrared spectroscopy and ex-situ X-ray photoelectron spectroscopy verifies the highly reversible structural change of zinc hexacyanoferrate during charge/discharge process. All these evidences suggest that zinc hexacyanoferrate may be a promising host material for Co2+ storage in aqueous rechargeable batteries.

Regulating the Zn electrode/electrolyte interface with lactose additive for high performance Zn anode

The practical utilization of rechargeable aqueous zinc metal batteries (AZMBs) has been constrained by the formation of zinc dendrites and other associated issues. This article introduces lactose, a compound rich in hydroxyl groups, as an electrolyte additive into the aqueous solution of the electrolyte with the objective of suppressing the harmful growth of zinc dendrites. The lactose additive, with its strong zincophilicity, robust intermolecular hydrogen bonding, and a large number of exposed high electronegativity hydroxyl groups, enables lactose to effectively modulate the electrode/electrolyte interface in a dynamic manner, thereby achieving the stability and reversibility of the zinc anode. The findings presented in this work demonstrate the uniform deposition and stripping of zinc in a 2 M ZnSO4 electrolyte with the addition of lactose, thereby enhancing the cycling performance of Zn||Zn batteries. The alteration of the zinc ion environment on the surface of the zinc electrode, in conjunction with the dynamic modulation of the Gouy-Chapman-Stern (GCS) layer by lactose, increases the nucleation overpotential, thereby facilitating to a uniform deposition morphology in lieu of the formation of large-scale dendrites. Furthermore, the formation of hydrogen bonds serves to prevent the occurrence of side reactions. These factors act in concert to enhance the electrochemical performance of AZMBs. The addition of lactose to the electrolyte has resulted in a significant enhancement in the Coulombic efficiency of the card-type Zn||Cu asymmetric battery, reaching 99.7 %. The biodegradability of lactose and the sustainability of its source make this research conducive to the development of environmentally friendly battery electrolyte additives.

A highly water-soluble phenoxazine quaternary ammonium compound catholyte for pH-neutral aqueous organic redox flow batteries

The pH-neutral aqueous redox flow battery (ARFB) is one of the most attractive flow batteries due to its non-corrosiveness, low-cost, and wider electrochemical stability window compared to those with acidic or alkaline electrolytes. However, there are few families of organic redox-active molecules available as catholyte materials for pH-neutral ARFBs. Herein, through incorporation of quaternary ammonium moiety into the redox-active phenoxazine nucleus, an organic catholyte material, N, N, N-trimethyl-2-(10H-phenoxazin-10-yl) ethan-1-aminium chloride (NEt-POZ) is achieved for pH-neutral ARFBs. The NEt-POZ has a high redox potential of 0.79 V versus SHE and rapid redox kinetics (0.23 cm s−1) as well as high water-solubility (∼2.6 M in H2O). Paired with a methyl viologen (MV) anolyte in the pH-neutral aqueous electrolyte, a viologen-phenoxazine ARFB full cell is assembled, which shows an open circuit voltage of ∼1.23 V. However, the results of long-term cycling experiments indicate low Coulomb efficiency and rapid declining capacity of the NEt-POZ catholyte. The mechanism analysis unveils that the unstable doubly oxidized tri-cations (NEt-POZ3+) formed via the disproportionation of radical di-cations (NEt-POZ2+) in solution readily react with chloride anions to form poly-chlorinated derivatives, which precipitate from the catholyte due to their poor water solubility, leading to a rapid decrease in capacity. When there is no chloride present in the electrolyte solution, highly reactive NEt-POZ3+ cations can interact with other counter-anions (such as sulfate and carbonate ions) and even water to form complex adducts.

Strong Lewis Electron-Pair Bonding in Vanadium Oxide for Ultra-fast and Long-term Stable Zn-ion Storage

Vanadium-based oxides typically show low electrical conductivity, high repulsion for Zn2+, and severe structure collapse problems, resulting in unsatisfied cathode performance for aqueous Zn-ion batteries (AZIBs). Herein, we propose an advanced structural optimization strategy to address the above issues by constructing strong Lewis electron-pair bonding in vanadium oxide through initial doping Ca and a subsequent in-situ electrochemical activation process. We prepared the precursor of Ca-doped and amorphous carbon-encapsulated V2O3 material (Ca0.17V2O3-x@C) and verified a phase transition into a layered V2O5-typed cathode during the activation process. Importantly, we find the initial-doped Ca and generated abundant oxygen vacancy defects are well restored in the phase-transformed crystal lattice. We reveal that band and bond structures of the phase-transformed cathode are optimized, exhibiting an improved electrical conductivity, optimal Zn2+ binding energy, ultra-low Zn-ion transport barrier, and considerably strong bonds of Ca-O and V-O, thereby realizing enhanced reaction kinetics and stability. The Ca0.17V2O3-x@C exhibits surprisingly high-rate performance (233 mAh g–1 at 40 A g–1) and excellent cycling stability (10,000 cycles with 82% retention at 20 A g–1). This work offers a novel and simple band and bond structure engineering strategy for preparing high-performance phase transformation typed vanadium oxide cathodes for AZIBs.

Functionalized Quasi-Solid-State Electrolytes in Aqueous Zn-Ion Batteries for Flexible Devices: Challenges and Strategies.

The rapid development of wearable and intelligent flexible devices has posed strict requirements for power sources, including excellent mechanical strength, inherent safety, high energy density, and eco-friendliness. Zn-ion batteries with aqueous quasi-solid-state electrolytes (AQSSEs) with various functional groups that contain electronegative atoms (O/N/F) with tunable electron accumulation states are considered as a promising candidate to power the flexible devices and tremendous progress has been achieved in this prospering area. Herein, this review proposes a comprehensive summary of the recent achievements using the AQSSE in flexible devices by focusing on the significance of different functional groups. The fundamentals and challenges of the ZIBs are introduced from a chemical view in the first place. Then, the mechanism behind the stabilization of the flexible ZIBs with the functionalized AQSSE is summarized and explained in detail. Then the recent progress regarding the enhanced electrochemical stability of the ZIBs with the AQSSE is summarized and classified based on the functional groups on the polymer chain. The advanced characterization methods for the AQSSE are briefly introduced in the following sections. Last but not least, current challenges and future perspectives for this promising area are provided from the authors' point of view.

Realizing Dual-Mode Zinc-Ion Storage of Generic Vanadium-Based Cathodes via Organic Molecule Intercalation.

Intercalation engineering is a promising strategy to promote zinc-ion storage of layered cathodes; however, is impeded by the complex fabrication routes and inert electrochemical behaviors of intercalators. Herein, an organic imidazole intercalation strategy is proposed, where V2O5 and NH4V3O8 (NVO) model materials are adopted to verify the feasibility of the imidazole intercalator in improving the zinc storage capabilities of vanadium-based cathodes. The intercalated imidazole molecules could not only expand interlayer spacing and strengthen structural stability by serving as extra "pillars" but also provide extra coordination sites for zinc storage via the coordination reaction between Zn2+ and the C═N group. This gives rise to a dual-mode ion storage mechanism and favorable electrochemical performances. As a result, imidazole-intercalated V2O5 delivers a capacity of 179.9 mAh g-1 after 5000 cycles at 20 A g-1, while the imidazole-intercalated NVO harvests a high capacity output of 170.2 mAh g-1 after 700 cycles at 2 A g-1. This work is anticipated to boost the application potentials of vanadium-based cathodes in aqueous zinc-ion batteries.

Proton Intercalation into an Open‐Tunnel Bronze Phase with Near‐Zero Volume Change

AbstractManaging safety and supply‐chain risks associated with lithium‐ion batteries (LIBs) is an urgent task for sustainable development. Aqueous proton batteries are attractive alternatives to LIBs because using water and protons addresses these two risks. However, most host materials undergo large volume changes upon H+ intercalation, which induces intraparticle cracking to accelerates parasitic reactions. Herein, we report that Mo3Nb2O14 bronze exhibits reversible H+ intercalation (200 mAh g−1) with a Coulombic efficiency of 99.7 % owing to near‐zero volume change and solid‐solution‐type phase transition. Combination of experimental and theoretical analyses clarifies that rotation and shrinkage of open tunnels, which consist of flexible corner‐sharing Mo/NbOn polyhedra, relieve local structural distortions upon H+ intercalation to suppress intraparticle cracking. The prototype full cell of an aqueous proton battery with a Mo3Nb2O14 anode operates stably over 1000 charge/discharge cycles. This study reveals the importance of implementing distortion‐relieving voids in host materials to reduce volume change upon charge/discharge.

Effective Water Confinement and Dual Electrolyte–Electrode Interfaces by Zwitterionic Oligomer for High‐Voltage Aqueous Lithium‐Ion Batteries

AbstractAqueous lithium‐ion batteries (ALIBs) have attracted significant interest due to their inherent advantage on safety. However, water itself has a narrow electrochemical stability window (ESW), limiting the energy density of ALIBs. Here, a low‐molecular‐weight zwitterionic oligomer, oligo(propylsulfonate dimethylammonium propylmethacrylamide) (OPDP), as an effective water binding agent for high‐voltage ALIBs is demonstrated. The OPDP can effectively confine water molecules while reducing water activity. The OPDP‐based electrolyte, with an ultra‐high water weight percentage of 25.4%, possesses an outstanding ESW of up to 3.26 V and an ionic conductivity as high as 3.18 mS cm−1. Furthermore, the aqueous Mo6S8//LiMn2O4 full cell with OPDP‐based electrolyte achieves a 99.7% capacity retention after 200 cycles at 0.5C with a high Coulombic efficiency (CE) of 98.7% and a specific energy of 88–101 Wh kg−1. Also, it achieves an 89% capacity retention after 2000 cycles at 10C with a high CE of 99.9%. These postmortem characterizations suggest that robust organic–inorganic hybrid cathode/anode‐electrolyte interfaces have been constructed during the cycling through the heteroatoms of N, S, and O in the zwitterionic oligomer, leading to the inhibited hydrogen/oxygen evolution reactions and high performance of the full cell. This work provides a promising strategy for developing low‐cost and high‐voltage aqueous batteries.

Combination Displacement/Intercalation Reaction of Ag0.11V2O5 Cathode Realizes Efficient Manganese Ion Storage Properties.

Aqueous manganese-ion batteries (AMIBs) are becoming more noticeable because of their excellent theoretical capacity, outstanding safety profile, and cost-effectiveness. However, there aren't many studies on cathode materials appropriate for AMIBs, and the manganese-ion storage mechanisms within these materials have not been thoroughly investigated. Furthermore, the electrochemical performance of existing cathode materials remains suboptimal. Here, Ag0.11V2O5 is designed and synthesized as the cathode material and introduces the combination displacement/intercalation reaction mechanism to the manganese ion storage for the first time. Ag0.11V2O5 demonstrates a capacity retention of 90.3% after 1200 cycles at 5 A g⁻¹ and achieves a high rate performance of 100.01 mAh g⁻¹ at 20 A g⁻¹. This impressive electrochemical performance is attributed to the reaction, which provides more Mn2+ storage sites and generates highly conductive Ag within the electrode. This study presents a novel approach to achieving high-capacity AMIBs.

A Dynamically Ion‐Sieved Electrolyte towards Ultralong‐Lifespan Zn‐Ion Batteries

AbstractThe practical deployment of Zn‐ion batteries faces challenges such as dendrite growth, side reactions and cathode dissolution in traditional electrolytes. Here, we develop a highly conductive and dynamically ion‐sieved electrolyte to simultaneously enhance the Zn metal reversibility and suppress the cathode dissolution. The dynamic ion screen at the electrode/electrolyte interface is achieved by numerous pyrane rings with a radius of 3.69 Å, which can selectively facilitate the plating/stripping and insertion/extraction process of [Zn(H2O)6]2+ and Zn2+ on the anode and cathode surfaces. As a proof of concept, Zn//Zn symmetric cells deliver exceptional cyclic stability for over 6,800 h and ultrahigh cumulative plated capacity of 1.95 Ah cm−2. Zn//Na2Mn3O7 cells exhibit satisfactory cycling performance with capacity retention of 82.7 % after 4,000 cycles, and the assembled pouch cells achieve excellent stability and durability. This work provides valuable insights into the development of electrolytes aimed at enhancing the interface stability of aqueous batteries.

Bifunctional Fluorocarbon Electrode Additive Lowers the Salt Dependence of Aqueous Electrolytes.

The solid electrolyte interphase (SEI) plays a crucial role in extending the life of aqueous batteries. The traditional anion-derived SEI formation in aqueous electrolytes highly depends on high-concentrated organic fluorinating salts, resulting in low forming efficiency and long-term consumption. In response, this study proposes a bifunctional fluorocarbon electrode additive (BFEA) that enables electrochemical pre-reduction instead of TFSI anion to form the LiF-rich SEI and in situ produce conductive graphite inside the anode before the lithiation. The BFEA lowers the salt dependence of aqueous electrolytes, enabling the inorganic LiCl electrolyte to work first, but also successfully achieves a high SEI formation efficiency in the relatively low 10m LiTFSI without mass transfer concerns, suppressing the parasitic hydrogen evolution from 11.24 to 4.35nmol min-1. Besides, BFEA strengthens the intrinsic superiority of Li storage reaction by lowering battery polarization resulting from the in situ production of graphite, promoting charge transfer of electrode kinetics. Compared with the control group, the demonstrated Ah-level pouch cell employing BFEA exhibits better cycle stability above 300 cycles with higher capacity retention of 78.2% and the lower decay of the round-trip efficiency (△RTE = 2%), benefiting for maintaining the high efficiency and reducing heat accumulation in large-scale electric energy storage.

Dual zinco-phobic/-philic ferroelectric nanorods coated mesh for stable Zn anode

Aqueous Zn-ion batteries are emerging as a promising option for energy storage systems due to their safety and environmental benefits. However, their stability and reversibility are often hindered by dendrite growth and interfacial side reactions. In this study, we introduce an innovative strategy to address these issues by engineering an artificial interfacial layer (AIL) on Zn anode surface. This AIL is composed of a dual zinco-phobic/-philic ferroelectric nanorods (FE NRs) mesh, which contrasts with the traditional BaTiO3 nanoparticles. The BTO NRs, particularly those with exposed P4/mmm (100) and (211) facets enriched with oxygen vacancy, facilitate a partial phase transition from the FE tetragonal P4mm phase to the paraelectric tetragonal P4/mmm phase, thereby creating dual zinco-phobic/-philic sites. Additionally, the integration of microchannels within the FE BTO NRs mesh can efficiently modulate the electric field distribution and Zn2+ concentration, leading to a more uniform Zn deposition, as conformed by electrochemical simulations. The Zn anode coated with the FE BTO NRs mesh exhibits impressive performance, achieving an ultralong cycle life of 3050 h at 1 mA cm−2 and 1mAh cm−2. It sustains a Coulombic efficiency exceeding 99.8 % over 2000 cycles, highlighting its exceptional reversibility. These findings underscore the potential of the dual zinco-phobic/-philic FE NRs mesh in overcoming the challenges faced in aqueous metal-ion batteries, showcasing its versatility and the significant performance enhancements it can offer.

MnO2 nanowires modified reduced graphene oxide thick film cathode for aqueous zinc-ion prismatic battery

Aqueous zinc-ion batteries are an excellent alternative to lithium-ion batteries that can meet the energy requirements while also being safe and eco-friendly. However, developing a suitable cathode material with good energy density and high-rate capability is challenging. In this study, we developed an aqueous zinc-ion battery with a high surface area MnO2 nanowires modified reduced graphene oxide nanocomposite screen printed interdigitated array electrodes and a distinctive aqueous electrolyte comprising 1 M each of ZnSO4 and Na2SO4, 0.1 M MnSO4, and 0.8 mM sodium dodecyl sulfate. The charge-discharge curves reveal that the cathode material exhibits a high reversible storage capacity of 164 mAh g−1 at a current density of 50 mA g−1. The battery retained 99.59% of its Coulombic efficiency after 300 cycles when cycled at a high current rate of 300 mA g−1. The prismatic battery realized exhibited a calculated energy density of 505.5 Wh kg−1 which is higher than previously reported works. On account of the large energy density and high rate capability coupled with non-toxic components, low cost and facile fabrication method, the Zn||MnO2/rGO battery shows good promise for energy storage application.

Nanocellulose-based ion-selective membranes for an aqueous organic redox flow battery

Nanocellulose-based ion-selective membranes for an aqueous organic redox flow battery

Rational design of α-MnO2@TiO2 composites for high-performance zinc ions batteries

Aqueous zinc ions batteries (AZIBs) have attracted widespread interest due to their remarkable energy density, non-toxicity, environmental friendliness and low cost. However, the application of MnO2 cathode materials for AZIBs is limited owing to the dissolution of Mn2+, structural collapse and intrinsic poor conductivity. Herein, α-MnO2@TiO2 composites were synthesized via simple hydrothermal and calcination approaches. Some smaller TiO2 were coated on the MnO2 nanorods to form the protective layer. The TiO2 protective layer not only prevents the dissolution of Mn2+ and structural collapse of MnO2, but also enhances the conductivity of the material due to the presence of Ti3+ defects, which increased electrode materials wettability, specific surface area and diffusion rate of Zn2+. In addition, the coating TiO2 causes surface adsorbed oxygen and surface binding defects in α-MnO2@TiO2, and increases surface reactivity and electrochemically active sites, which provides abundant channels and available insertion electrochemically active sites for H+/Zn2+ transport. As a result, α-MnO2@TiO2–2 delivers a high specific capacity of 182.90 mAh g−1 at 1 A g−1 after 600 cycles and outstanding rate capacity of 127.91 mAh g−1 at 5 A g−1. This work provides an idea for exploring high-performance cathode materials for AZIBs.

Constructing Quasi-Single Ion Conductors by a β-Cyclodextrin Polymer to Stabilize Zn Anode.

Aqueous Zn-ion batteries (AZIBs) are promising for the next-generation large-scale energy storage. However, the Zn anode remains facing challenges. Here, we report a cyclodextrin polymer (P-CD) to construct quasi-single ion conductor for coating and protecting Zn anodes. The P-CD coating layer inhibited the corrosion of Zn anode and prevented the side reaction of metal anodes. More important is that the cyclodextrin units enabled the trapping of anions through host-guest interactions and hydrogen bonds, forming a quasi-single ion conductor that elevated the Zn ion transference number (from 0.31 to 0.68), suppressed the formation of space charge regions and hence stabilized the plating/striping of Zn ions. As a result, the Zn//Zn symmetric cells coated with P-CD achieved a 70.6 times improvement in cycle life at high current densities of 10 mA cm-2 with 10 mAh cm-2. Importantly, the Zn//K1.1V3O8 (KVO) full-cells with high mass loading of cathode materials and low N/P ratio of 1.46 reached the capacity retention of 94.5 % after 1000 cycles at 10 A g-1; while the cell without coating failed only after 230 cycles. These results provide novel perspective into the control of solid-electrolyte interfaces for stabilizing Zn anode and offer a practical strategy to improve AZIBs.

Evolution of Frustrated Coordination in Eutectic Electrolyte Driven by Ligand Asymmetry toward High-Performance Zinc Batteries.

Eutectic electrolytes hold promise for aqueous zinc metal batteries in sustainable energy storage chemistries, yet improvement from perspective of molecule configurational engineering are ambiguous. Herein, we propose design strategy of increasing asymmetric molecular geometry in organic ligands to regulate frustrated coordination and disordered structure for eutectic electrolytes toward enhanced zinc metal batteries. The introduced asymmetry in eutectic component gives rise to relatively weak coordination strength and configurational disorder interaction among cation-anion-ligand, leading to suppressed local aggregation, steady eutectic phase and improved Zn2+diffusion kinetics. Such highly frustrated coordination state also enables disruption of hydrogen bonding network and reinforcement of anion participation, which results in confined side reactions, decreased water activity and the formation of inorganic-enriched solid electrolyte interphase. In comparison to highly symmetric ligands, asymmetric ligand-involved eutectic electrolytes with configurational disorderdeliver high Coulombic efficiency of 99.4 %, stabilized Zn plating/stripping of 5000 h and impressive rate capability even under harsh conditions such as small N/P, low temperature. The rationale in this work advances the deep understanding of asymmetric molecular engineering in eutectic electrolytes and showcases suitability of frustrated coordination to achieve high-performance zinc metal batteries.

A High-Voltage n-type Organic Cathode Materials Enabled by Tetraalkylammonium Complexing Agents for Aqueous Zinc-Ion Batteries.

Tetrabutylammonium (TBA) salt of hexacyano-substituted cyclopropane dianion (Cp(CN)6 2 -) is prepared through a facile two-step synthetic protocol from commercially available materials and fully characterized as a high-voltage n-type organic cathode in rechargeable aqueous zinc-ion batteries (AZIBs). The addition of tetrabutylammonium triflate (TBAOTf)to the electrolyte mitigates dissolution issues, leading to enhanced cycling stability. Remarkably, the Cp(CN)6 2 - cathode demonstrates a high discharge voltage of 1.43V in AZIBs and retains 85% of its capacity after 1000 cycles at a high loading of 10mg cm- 2 and a cycling rate of 10C. These results, combined with spectroscopic analyses, elucidate a reversible two-electron redox process of Cp(CN)6 2 - facilitated by the insertion/de-insertion of TBA cation. These findings underscore the potential of Cp(CN)6 2 - as a conversion-based n-type cathode in energy storage applications.