Hybrid Aqueous Battery Research Articles

Polymer Electrolytes with High Ionic Conductivities at Freezing Temperature for Aqueous Hybrid Batteries.

Rechargeable and flexible aqueous batteries (ABs) have emerged as one of promising energy devices which is primarily due to the safety, environmental friendliness and economic efficiency. However, because of the freezing behavior of aqueous electrolytes, most ABs possess poor performance when the working temperature drops below zero. To solve this problem, a gel polymer electrolyte (GPE) with high ionic conductivity (IC) and frost-resistance is designed for aqueous Zn-Li hybrid batteries by a biomass-based polymers complex consisting of carboxyl modified sodium alginate (SA) and zwitterionic betaine (BA). Introducing iminodiacetic acid to enrich -COOH groups along the SA main chains could improve IC of the prepared GPEs to 41.27 and 20.96 mS cm-1 at 20 and -20 °C, respectively. At -20 °C, the discharge capacity of the resultant cell is two times higher than that of the liquid electrolyte-based cell, and the cell presents a capacity retention of 91.6 % after 300 charge/discharge cycles at 1 C. This proposed strategy greatly improve the IC of GPEs at freezing temperature, which is expected to broaden the practical application of GPEs in wide range of temperature.

Deciphering the multi-electron redox chemistry of metal-sulfide electrode toward advanced aqueous Cu ion storage

While neutral aqueous metal batteries, featuring cost-effectiveness and non-flammability, hold significant potential for large-scale energy storage, their practical application is hampered by the limited specific capacity of cathode materials (less than 500 mAh g−1). Herein, capacity-oriented CoS2 and rate-optimized Co9S8 cathodes are developed based on the aqueous copper ion system. The charge-storage mechanism is systematically investigated through a series of ex-situ tests and density functional theory calculations, focusing on the reversible transitions of Co9S8→Cu7S4→Cu9S5/Cu1.8S and CoS2→Cu7S4→Cu2S, which are associated with the redox reactions of Cu2+/Cu+‖Co2+/Co and Cu2+/Cu+‖S22−/S2−, respectively. The electrochemical results show that CoS2 can exhibit a superior capacity of 619 mAh g−1 at 1 A g−1 after 400 cycles, while Co9S8 maintains an outstanding rate performance of 497 mAh g−1 at 10 A g−1 (the retention rate is 95% compared to 521 mAh g−1 at 1 A g−1). As a proof of concept, an advanced CoS2//Zn hybrid aqueous battery demonstrates a working voltage of 1.20 V and a specific energy of 663 Wh kgcathode−1. This work provides an alternative direction for developing sulfide cathodes in energetic aqueous metal batteries.

Elucidating the Mechanism of Solid-Electrolyte Interphase Formation in Hybrid Aqueous Zn-Ion Batteries

The formation of a favorable solid-electrolyte interphase (SEI) is essential to the reversible performance of zinc metal anodes in aqueous solutions. Thus far, it has been well agreed that the interphase layer should be passivating, ionically conductive, electronically insulating, and ideally self-repairable. When comprised of both organic and inorganic components, an SEI can effectively prevent hydrogen evolution reaction (HER) and corrosion on the metal surface, resulting in increased Coulombic efficiency and overall longevity. Here, we report the use of in-depth spectroscopic and electrochemical techniques to understand the unique solvation and decomposition of dimethyl carbonate (DMC) in high concentrated zinc water-in-salt electrolyte. Nuclear Magnetic Resonance (NMR) of both the liquid and solid states reveal an unusual dual reaction pathway that allows for the formation of a hybrid organic/inorganic SEI capable of achieving unprecedented capacity retention for zinc metal batteries.

Atomic Level‐Macroscopic Structure‐Activity of Inhomogeneous Localized Aggregates Enabled Ultra‐Low Temperature Hybrid Aqueous Batteries

The utilization of hybrid aqueous electrolytes has significantly broadened the electrochemical and temperature ranges of aqueous batteries, such as aqueous zinc and lithium‐ion batteries, but the design principles for extreme operating conditions remain poorly understood. Here, we systematically unveil the ternary interaction involving salt‐water‐organic co‐solvents and its intricate impacts on both the atomic‐level and macroscopic structural features of the hybrid electrolytes. This highlights a distinct category of micelle‐like structure electrolytes featuring organic‐enriched phases and nanosized aqueous electrolyte aggregates, enabled by appropriate low donor number co‐solvents and amphiphilic anions. Remarkably, the electrolyte enables exceptional high solubility, accommodating up to 29.8 m zinc triflate within aqueous micelles. This configuration maintains an intra‐micellar salt‐in‐water setup, allowing for a broad electrochemical window (up to 3.86 V), low viscosity, and state‐of‐the‐art ultralow‐temperature zinc ion conductivity (1.58 mS cm−1 at –80°C). Building upon the unique nature of the inhomogeneous localized aggregates, this micelle‐like electrolyte facilitates dendrite‐free Zn plating/stripping, even at –80°C. The assembled Zn||PANI battery showcases an impressive capacity of 71.8 mAh g−1 and an extended lifespan of over 3000 cycles at −80°C. This study opens up a promising approach in electrolyte design that transcends conventional local atomic solvation structures, broadening the water‐in‐salt electrolyte concept.

Atomic Level-Macroscopic Structure-Activity of Inhomogeneous Localized Aggregates Enabled Ultra-Low Temperature Hybrid Aqueous Batteries.

The utilization of hybrid aqueous electrolytes has significantly broadened the electrochemical and temperature ranges of aqueous batteries, such as aqueous zinc and lithium-ion batteries, but the design principles for extreme operating conditions remain poorly understood. Here, we systematically unveil the ternary interaction involving salt-water-organic co-solvents and its intricate impacts on both the atomic-level and macroscopic structural features of the hybrid electrolytes. This highlights a distinct category of micelle-like structure electrolytes featuring organic-enriched phases and nanosized aqueous electrolyte aggregates, enabled by appropriate low donor number co-solvents and amphiphilic anions. Remarkably, the electrolyte enables exceptional high solubility, accommodating up to 29.8 m zinc triflate within aqueous micelles. This configuration maintains an intra-micellar salt-in-water setup, allowing for a broad electrochemical window (up to 3.86 V), low viscosity, and state-of-the-art ultralow-temperature zinc ion conductivity (1.58 mS cm-1 at -80 °C). Building upon the unique nature of the inhomogeneous localized aggregates, this micelle-like electrolyte facilitates dendrite-free Zn plating/stripping, even at -80 °C. The assembled Zn||PANI battery showcases an impressive capacity of 71.8 mAh g-1 and an extended lifespan of over 3000 cycles at -80 °C. This study opens up a promising approach in electrolyte design that transcends conventional local atomic solvation structures, broadening the water-in-salt electrolyte concept.

A Unified Charge Storage Mechanism to Rationalize the Electrochemical Behavior of Quinone-Based Organic Electrodes in Aqueous Rechargeable Batteries.

Due to their eco-sustainability and versatility, organic electrodes are promising candidates for large-scale energy storage in rechargeable aqueous batteries. This is notably the case of aqueous hybrid batteries that pair the low voltage of a zinc anode with the high voltage of a quinone-based (or analogue of quinone-based) organic cathode. However, the mechanisms governing their charge-discharge cycles remain poorly understood and are even a matter of debate and controversy. No consensus exists on the charge carrier in mild aqueous electrolytes, especially when working in an electrolyte containing a multivalent metal cation such as Zn2+. In this study, we comprehensively investigate the electrochemical reactivity of two model quinones, chloranil, and duroquinone, either diluted in solution or incorporated into carbon-based composite electrodes. We demonstrate that a common nine-member square scheme proton-coupled electron transfer mechanism allows us to fully describe and rationalize their electrochemical behavior in relation to the pH and chemical composition of the aqueous electrolyte. Additionally, we highlight the crucial role played by the pKas associated with the reduced states of quinones in determining the nature of the charge carrier that compensates for the negative charges reversibly injected in the active material. Finally, contrary to the widely reported findings for Zn/organic batteries, we unequivocally establish that the predominant solid-state charge carriers in Zn2+-based mild aqueous electrolytes are not multivalent Zn2+ cations but rather protons supplied by the weakly acidic hexaaqua metal ions (i.e., [Zn(H2O)6]2+]).

An aqueous rechargeable copper ammonium hybrid battery with good cycling performance

This work assembles an aqueous rechargeable copper ammonium hybrid battery, which combines the merits of an NH4+-rich copper hexacyanoferrate (N-CuHCF) cathode and the high safety, high capacity, and abundant reserves of a Cu anode.

Engineering of hydrogel electrolyte for aqueous Zn||LiFePO4 battery on subzero-temperature adaptability, long cycles and mechanical safety

Aqueous Zn||LiFePO4 (Zn||LFP) hybrid batteries are gaining increasing interest because of their stable charging/discharging, non-flammability, low cost, and environmental friendliness. However, aqueous hybrid batteries still face the challenges of sluggish charge transfer and ion diffusion processes due to electrolyte freezing at subzero temperatures. Herein, we designed an antifreeze hydrogel electrolyte for low-temperature Zn||LFP battery. This hydrogel electrolyte is comprised of double-network κ-carrageenan/PAAm containing moderately concentrated electrolyte (1 M ZnCl2 and 7 M LiCl), possesses high elasticity with a fracture strain of 834% and high ionic conductivity of 14.8 mS cm−1 at −40 °C. It also enables a stable Zn plating/stripping efficiency with reduced interface resistance and alleviates undesired H2 evolution. The corresponding flexible Zn||LFP battery with hydrogel electrolyte displays outstanding cycle stability with capacity retentions of 95.2% and 80.5% after 2000 cycles at −20 °C and −40 °C, respectively. In addition, the battery exhibits low self-discharge rate and retains good electrochemical stability under different destructive mechanical testing including bending, folding, and puncturing. Owing to the ion-orientation effect, cooperative solvation effect, and interface wettability, the hydrogel electrolyte endows Zn||LFP battery with prolonged cyclability, subzero-temperature operation, and mechanical safety as compared to the liquid electrolyte counterpart.

An advanced Ca/Zn hybrid battery enabled by the dendrite-free zinc anode and a reversible calcification/decalcification NASICON cathode

The proposal of hybrid ion batteries, which can integrate the advantages of the single ion battery, opens up a new route for developing high-performance secondary batteries. Herein, we successfully constructed an aqueous hybrid battery comprised of polyanionic-type cathode material (Na3V2(PO4)3, NVP), Zn metal anode, and aqueous Ca2+/Zn2+ hybrid electrolyte. This exciting combination gives full play to not only the excellent diffusion dynamics of Ca2+ in the NASICON (sodium super ion conductors) structure but also the electrostatic shielding effect of Ca2+ with low reduction potential that inhibits the formation of zinc dendrites. As results, the NVP//Zn Zn/Ca hybrid battery delivers favorable specific capacity with outstanding rate performance (85.3 mAh g−1 capacity at 1 C, 60.5 mAh g−1 capacity at 20 C), and excellent cycle stability (74 % capacity retention after 1300 cycles).

Novel ferrocene-containing amphiphilic block copolymer nanoparticles as high-capacity charge carriers in aqueous redox flow systems

Size-exclusion polymer electrolytes are promising charge carriers to diminish the crossover and allowing commercially available low-cost porous membranes in redox flow batteries. Boosting the solubility in water and maximizing the number of redox sites to enhance the capacity of these polymeric systems is challenging. New highly water dispersed amphiphilic diblock copolymers are reported here, with an average concentration value of 1.7 10−3 mmol of Ferrocene (Fc)-linked moieties per mg of polymer, determined by total X-ray reflection fluorescence. These redox amphiphilic block copolymers are stabilized in water as spherical nanoparticles (20 nm) by using a simple phase solvent inversion procedure. We evidence a maximum polymer dispersibility value of 6 g/L in water, for long-term stable polymer nanoparticle suspensions, yielding a theoretical capacity value of 4.78 mAh at 10.5 mM Fc. Further adjustment of the ionic conductivity and pH of these stable redox block copolymer suspensions has rendered a conductivity value of 44.5 mS/cm at pH values close to a neutral one, by adding a variety of salt supports. Studies using a 3-electrode configuration cell reveal an efficient charge transport between each of the Fc motifs in the polymer nanoparticle. A capacity value of 3.1 mAh with no transient of the polymer nanoparticles crosswise the cheap porous membrane is evidenced when cycled as polycatholyte material in a Zn hybrid aqueous redox flow battery. The particle size and electronic changes of these novel amphiphilic redox block copolymer electrolytes during consecutive redox cycles have also been monitored by dynamic light scattering and ultraviolet-visible spectroscopy, respectively. The analysis of the results enables the understanding of the main mechanisms behind their non-fully reversible capacity. Among them, aggregation and sedimentation, along with retention inside the graphite felt electrode acting the latter as a filter. These insights will aid the design of future polymer electrolyte materials and redox flow battery components with better performance and cost.

Activating sulfur oxidation reaction via six-electron redox mesocrystal NiS2 for sulfur-based aqueous batteries.

Sulfur-based aqueous batteries (SABs) are deemed promising candidates for safe, low-cost, and high-capacity energy storage. However, despite their high theoretical capacity, achieving high reversible value remains a great challenge due to the thermodynamic and kinetics problems of elemental sulfur. Here, the reversible six-electron redox electrochemistry is constructed by activating the sulfur oxidation reaction (SOR) process of the elaborate mesocrystal NiS2 (M-NiS2). Through the unique 6e- solid-to-solid conversion mechanism, SOR efficiency can reach an unprecedented degree of ca. 96.0%. The SOR efficiency is further revealed to be closely associated with the kinetics feasibility and thermodynamic stability of the M-NiS2 intermedium in the formation of elemental sulfur. Benefiting from the boosted SOR, compared with the bulk electrode, the M-NiS2 electrode exhibits a high reversible capacity (1258mAhg-1), ultrafast reaction kinetics (932 mAh g-1 at 12 A g-1), and long-term cyclability (2000cycles at 20 A g-1). As a proof of concept, a new M-NiS2‖Zn hybrid aqueous battery exhibits an output voltage of 1.60V and an energy density of 722.4Wh kgcath-1, which opens a new opportunity for the development of high-energy aqueous batteries.

A dilute fluorine-free electrolyte design for high-voltage hybrid aqueous batteries

Fluorinated salts and/or high salt concentrations are usually necessary to produce protective films on the electrodes for high-voltage aqueous batteries, yet these approaches increase the cost, toxicity and reaction resistances of battery. Herein, we report a dilute fluorine-free electrolyte design to overcome this dilemma. By using the LiClO4 salt and polyethylene glycol dimethyl ether (PED) solvent and optimizing the LiClO4/PED/H2O molar ratio, we formulate a 1 mol kg−1 3 V-class hybrid aqueous electrolyte that enables reversible charge/discharge of 2.5 V LiMn2O4|Li4Ti5O12 full cell at both low (0.5C, 92.4% capacity retention in 300 cycles) and high (5C, 80.4% capacity retention in 2000 cycles) rates. This excellent performance is reached even without the generation of protective film on either anode or cathode as identified by in/ex situ characterizations. The selection of appropriate ingredients that have both high stability and strong interactions with water is critical to widen the potential window of electrolyte while suppressing parasitic reactions on the electrodes. This work suggests that expensive and toxic fluorinate salts are no longer necessary for 3 V-class aqueous electrolytes, boosting the development of low-cost, environmentally-friendly, high-power and high-energy-density aqueous batteries.

Bimetallic Rechargeable Al/Zn Hybrid Aqueous Batteries Based on Al-Zn Alloys with Composite Electrolytes.

Aluminum is abundant and exhibits a high theoretical capacity and volumetric energy density. Additionally, the high safety of aqueous aluminum-ion batteries makes them strong candidates for large-scale energystorage systems. However, the frequent collapse of the cathode material and passive oxide film results in the difficult development of aqueous aluminum-ion batteries. This work provides a novel battery system, namely, Al-Zn/Al(OTF)3 +HOTF+Zn(OTF)2 /Alx Zny MnO2 ·nH2 O, with a mixed electrolyte. The cathode applies MnO topology transformation to ensure that the cathode forms Alx MnO2 ·nH2 O. Topology transformation alters the structure of the cathode material so that Zn2+ can be intercalated into the Alx MnO2 ·nH2 O spinel structure to provide support for the material structure. Regarding the anode, Zn2+ in the electrolyte is deposited onto Al of the anode to produce a regional Al-Zn alloy. Zn2+ is reduced to Zn metal during discharging, which adds a platform for secondary discharge beneficial for battery capacity enhancement. This system can provide a 1.6V discharge platform, while the first cycle discharge can reach 554 mAhg-1 , thereby maintaining a high capacity of 313 mAhg-1 after 100 cycles. This study provides a new idea for the further development of aqueous aluminum-ion batteries (AAIBs).

A True Non-Newtonian Electrolyte for Rechargeable Hybrid Aqueous Battery

The rechargeable aqueous hybrid battery is a unique system in which the Li-ion mechanism dominates the cathode while the first-order metal reaction of stripping/depositing regulates the anode. This battery inherits the advantages of the low-cost anode while possessing the capability of the Li-ion cathode. One of the major challenges is to design a proper electrolyte to nourish such strengths and alleviate the downsides, because two different mechanisms are functioning separately at the node–electrolyte and the cathode–electrolyte interfaces. In this work, we design a non-Newtonian electrolyte which offers many advantages for a Zn/LiMn2O4 battery. The corrosion is kept low while almost non-dendritic zinc deposition is confirmed by chronoamperometry and ex situ microscopy. The gel strength and gelling duration of such non-Newtonian electrolytes can be controlled. The ionic conductivity of such gels can reach 60 mS⋅cm−1. The battery exhibits reduced self-discharge, 6–10% higher specific discharge capacity than the aqueous reference battery, high rate capability, nearly 80% capacity retention after 1000 cycles, and about 100 mAh⋅g−1 of specific discharge capacity at cycle No. 1000th. Negligible amorphization on the cathode surface and no passivation on the anode surface are observed after 1000 cycles, evidenced by X-ray diffraction and scanning electron microscopy on the post-run battery electrodes.

PPy-Modified Prussian Blue Cathode Materials for Low-Cost and Cycling-Stable Aqueous Zinc-Based Hybrid Battery

Prussian blue analogs are promising cathode materials in aqueous ion batteries that have attracted increasing attention, but their low specific capacity and limited cycling stability remain to be further improved. Effective strategies to optimize the electrochemical performance of Prussian blue cathode materials are the aspects of electrolyte and structure modification. In this work, Na2MnFe(CN)6@PPy nanocubes were prepared by a simple co-precipitation method with PPy coating. Compared with the uncoated electrode material, the discharged capacity of the Na2MnFe(CN)6@PPy cathode material is raised from 25.2 to 55.0 mAh g−1 after 10 cycles in the Na-Zn hybrid electrolyte, while the capacity retention is improved from 63.5% to 86.5% after 150 cycles, indicating higher capacity and better stability. This work also investigates the electrochemical performances of Na2MnFe(CN)6@PPy cathode material in hybrid electrolyte of Li-Zn and K-Zn adjusted via different mixed ion solutions. The relevant results provide an innovative way to optimize advanced aqueous hybrid batteries from the perspective of cycling stability.

Reducing atmosphere improves the conductivity of NaTi2(PO4)3/C material for hybrid aqueous rechargeable lithium-ion battery anode

Hybrid aqueous rechargeable lithium-ion batteries (HARLIBs) have lower cost and better safety performance than conventional lithium-ion batteries (organic electrolytes). The challenge faced by HARLIBs are the narrow selection of anode and cathode materials, and overcoming the problems of capacity decay of anode and cathode materials in aqueous electrolytes. NaTi2(PO4)3, which has a stable three-dimensional open framework structure, shows certain applicability in HARLIBs, but its inherent low electronic conductivity leads to poor utilization of active materials and inferior rate performance. In this article, we propose an experimental method that can improve the conductivity of NaTi2(PO4)3/C, and study the electrochemical performance of NaTi2(PO4)3/C aqueous half-cell and NaTi2(PO4)3/C||LiMn2O4 hybrid aqueous full cell. The results show that Ti3+/oxygen vacancies can endow NaTi2(PO4)3/C with higher conductivity and improve the specific capacity and rate capability (69 mAh·g−1, 7C). At 1C, the second discharge specific capacity is 98.46 mAh·g−1. After 100 cycles, the Rct was 2.92 × 10−2 Ω. The NaTi2(PO4)3/C//LiMn2O4 full cell can provide a discharge specific capacity of up to 101.07 mAh·g−1. The synthesized NaTi2(PO4)3/C material can be applied to the anode electrode of hybrid aqueous lithium-ion full cell.

3D printing of fast kinetics reconciled ultra-thick cathodes for high areal energy density aqueous Li–Zn hybrid battery

The limitation of areal energy density of rechargeable aqueous hybrid batteries (RAHBs) has been a significant longstanding problem that impedes the application of RAHBs in miniaturized energy storage. Constructing thick electrodes with optimized geometrical properties is a promising strategy for achieving high areal energy density, but the sluggish ion/electron transfer and poor mechanical stability, as well as the increased electrode thickness, itself present well-known problems. In this work, a 3D printing technique is introduced to construct an ultra-thick lithium iron phosphate (LFP)/carboxylated carbon nanotube (CNT)/carboxyl terminated cellulose nanofiber (CNF) composite electrode with uncompromised reaction kinetics for high areal energy density Li–Zn RAHBs. The uniformly dispersed CNTs and CNFs form continuous interconnected 3D networks that encapsulate LFP nanoparticles, guaranteeing fast electron transfer and efficient stress relief as the electrode thickness increases. Additionally, multistage ion diffusion channels generated from the hierarchical porous structure assure accelerated ion diffusion. As a result, LFP/Zn hybrid pouch cells assembled with 3D printed electrodes deliver a well-retained reversible gravimetric capacity of about 143.5 mAh g−1 at 0.5 C as the electrode thickness increases from 0.52 to 1.56 mm, and establish a record-high areal energy density of 5.25 mWh cm−2 with an impressive utilization of active material up to 30 mg cm−2 for an ultra-thick (2.08 mm) electrode, which outperforms almost all reported zinc-based hybrid-ion and single-ion batteries. This work opens up exciting prospects for developing high areal energy density energy storage devices using 3D printing.

High Energy, Long Cycle, and Superior Low Temperature Performance Aqueous Na-Zn Hybrid Batteries Enabled by a Low-Cost and Protective Interphase Film-Forming Electrolyte.

A hybrid aqueous Na-Zn ion battery derived from the Na3V2(PO4)3 cathode is one of the most promising systems among aqueous batteries because it exhibits higher energy density than a pure Zn ion battery due to different ion intercalation mechanisms related to various electrolytes. However, it is more difficult to improve the electrochemical performance of the hybrid aqueous Na-Zn ion battery versus Zn ion battery. In addition, searching for suitable protective interphase film-forming electrolyte additives in order to increase cycling stability and developing a new electrolyte recipe to improve the low temperature performance are significant and still big challenges for the hybrid aqueous Na-Zn battery. Herein, the introduction of protective interphase film-forming additives (VC), an economical 10 M NaClO4-0.17 M Zn(CH3COO)2-2 wt % VC electrolyte, was proposed. Based on such an electrolyte, the carbon-coated single crystalline Na3V2(PO4)3 nanofiber//Zn aqueous Na-Zn hybrid battery involving high energy, long cycle, and outstanding low temperature performance was successfully obtained. For example, it delivered a remarkable output voltage of 1.48 V and excellent cycle stability (retained 84% after 1000 cycles). The capacities were 94.4 mA h/g at 0.2 A/g at -10 °C and 90.0 mA h/g at 0.2 A/g at -20 °C, respectively.

The Li3V2(PO4)3@C materials prepared by freeze-drying assisted sol-gel method for an aqueous zinc ion hybrid battery

• An aqueous hybrid battery with Li 3 V 2 (PO 4 ) 3 @C as cathode and Zn as anode is proposed. • A uniform and dispersed morphology of Li 3 V 2 (PO 4 ) 3 @C was fabricated by freeze-drying assisted sol-gel method. • The effects of carbon content on morphology, structure and electrochemical properties of the materials were explored. In this paper, fast ion and electron delivery inside electrode materials, which is very crucial to the aqueous zinc-ion hybrid batteries (AZHBs), has been studied in order to achieve the excellent electrochemical performance. The Li 3 V 2 (PO 4 ) 3 @C (LVP@C) composites were successfully fabricated by freeze-drying assisted sol-gel method, and the effects of carbon content on the structure, morphology and electrochemical performance of LVP@C composites were investigated. XRD results suggested that the products were made up of an ideal monoclinic structure of LVP, and the structural changes of Li + intercalation and de-intercalation during charge-discharge process were verified. Particularly, the LVP@C-05 sample exhibits excellent crystallinity. SEM images presented that with the increase of carbon content, the size of particles is smaller, and the distribution of particles is more uniform and dispersed. Especially, the LVP@C-05 sample has the smallest and the most uniform dispersed particles. The charging-discharging results indicated that the LVP@C-05 sample delivers the highest initial capacity of 95mAh g −1 at the current density of 2C, and the capacity retention after 50th cycles is 91%. Even at 20C current density, the LVP@C-05 also shows an attractive discharge capacity as high as 67mAh g −1 . CV results presented that the ionic diffusion coefficient of the LVP@C-05 sample is the highest (2.59×10 −12 cm 2 s −1 ), compared to the value of LVP@C-0, LVP@C-03, LVP@C-07 sample. Besides, EIS and Nyquist plots fitting results indicated that the R ct of LVP@C-05 sample is the lowest (189.5 Ω), showing a lower charge transfer resistance and increasing the kinetics of the reaction.

Electrolyte additives inhibit the surface reaction of aqueous sodium/zinc battery

In aqueous zinc-based batteries, the reaction by-product Zn4SO4(OH)6·xH2O is commonly observed when cycling vanadium-based and manganese-based cathodes. This by-product obstructs ion transport paths, resulting in enhanced electrochemical impedance. In this work, we report a hybrid aqueous battery based on a Na0.44MnO2 cathode and a metallic zinc foil anode. The surfactant sodium lauryl sulfate is added to the electrolyte as a modifier, and the performance before and after modification is compared. The results show that sodium lauryl sulfate can generate an artificial passivation film on the electrode surface. This passivation film reduces the generation of Zn4SO4(OH)6·xH2O and inhibits the dissolution of Na0.44MnO2 in the electrolyte. Therefore, the reaction kinetics and cycle stability of the battery are significantly enhanced. A battery with this electrolyte additive delivers an initial discharge capacity of 235 mA h g−1 at a current density of 0.1 A g -1. At the same time, the battery has excellent rate performance. Under the high-rate condition of 1 A g−1, the battery still maintains a capacity retention rate of 93% after 1500 cycles. Finally, the functional mechanism of by-product inhibition by the electrolyte additive is discussed.