Proton Battery Research Articles

A rechargeable aqueous phenazine-Prussian blue proton battery with long cycle life

We report a high-performance rechargeable aqueous battery that operates with protons commuting between a fused-ring phenazine derivative anode and a Prussian blue analogue cathode.

An Amorphous Anode for Proton Battery

HighlightsAmorphous MoOx with pre-insertion of Al3+ was prepared via ion-exchange protocol.Al-MoOx anode had remarkable capacity and record-level cycling stability for proton battery.The proton battery using Al-MoOx anode achieved a high voltage of 1.37 V.

Biodegradable flexible proton conducting solid biopolymer membranes based on pectin and ammonium salt for electrochemical applications

One of the most significant difficulties confronting civilization today is the availability of renewable power generation for a growing and highly productive society. Solid-state batteries are expected to be advantageous in a wide variety of energy storage systems. The present work examines the synthesis and characterization of solid biopolymer membranes as electrolytes for solid-state primary proton battery applications from the viewpoint of renewable energy development. Solid biopolymer membranes (SBPMs) based on anionic polysaccharide host polymer pectin and proton donor ammonium iodide (AI) salt are synthesized via a facile solution cast technique. The impact of dopant salt concentration (30 M.wt % to 80 M.wt %) on the membranes' electrical, dielectric, transport, thermal, structural, and electrochemical properties was investigated. At ambient temperature, a maximum ionic conductivity of 4.5 × 10−3 S cm−1 has been achieved. The dielectric and transport properties of the prepared SBPMs are studied and correlated with the trend of ionic conductivity. With the highest conductive SBPM, the primary proton battery has been assembled. The discharge performance and open circuit voltage (OCV) were examined and recommended as a potential candidate for alternate research for low power density applications.

Accessing the proton storage in neutral buffer electrolytes using an electrodeposited molybdenum phosphate

• Introducing PO 4 3− in molybdenum oxide structure enhances the electron/ion conductivity. • Neutral buffer electrolytes possess fast and sufficient H + supplement for H + storage. • The MP electrode experiences pure H + storage in neutral buffer electrolytes. • The MP electrode exhibits a high capacity of 125.6 mAh g −1 with a high mass of 15.6 mg cm −2 . Proton as charge carrier provides unique merits over metal cations in aqueous batteries. Yet, aqueous proton batteries (APBs) usually use strongly acidic electrolytes, which may cause hydrogen evolution and corrosion issues. Herein, we fabricate a molybdenum phosphate (MP) electrode that experiences pure proton storage in neutral buffer electrolytes for the first time, breaking the limit of acidic electrolytes for APBs. The aqueous neutral buffer electrolytes possess fast proton transport network and proton-donor effect, affording fast and sufficient supplement of H + for the MP electrode. Benefiting from the mixed valence of Mo and enhanced surface electronegativity upon PO 4 3− introduction, the MP electrode exhibited superior discharge capacities to its oxide counterpart (MoO x ). The MP electrode exhibits good electrochemical performances, such as a high specific capacity of 125.6 mAh g −1 at 0.1 A g −1 (mass loading: 15.6 mg cm −2 ), which is just slightly lower than that (147 mAh g −1 ) tested in 1 M HCl electrolyte, a low cutoff potential of −1 V vs. SCE, and long cycle life with 87.8% capacity retention after 2500 charge-discharge cycles at 1.0 A g −1 . Our findings provide new opportunities for high-performance neutral proton batteries.

Polymer electrolyte based on guar gum and ammonium thiocyanate for proton battery application

Polymer electrolyte based on guar gum and ammonium thiocyanate for proton battery application

Molecular magneto-ionic proton sensor in solid-state proton battery

High proton conductivity originated from its small size and the diffusion-free Grotthuss mechanism offers immense promise for proton-based magneto-ionic control of magnetic materials. Despite such promise, the realization of proton magneto-ionics is hampered by the lack of proton-responsive magnets as well as the solid-state sensing method. Here, we report the proton-based magneto-ionics in molecule-based magnet which serves as both solid-state proton battery electrode and radiofrequency sensing medium. The three-dimensional hydrogen-bonding network in such a molecule-based magnet yields a high proton conductivity of 1.6 × 10−3 S cm−1. The three-dimensional printed vascular hydrogel provides the on-demand proton stimulus to enable magneto-ionics, where the Raman spectroscopy shows the redox behavior responsible for the magnetism control. The radiofrequency proton sensor shows high sensitivity in a wide proton concentration range from 10−6 to 1 molar under a low working radiofrequency and magnetic field of 1 GHz and 405 Oe, respectively. The findings shown here demonstrate the promising sensing application of proton-based magneto-ionics.

Aqueous proton batteries based on acetic acid solutions: mechanistic insights

Large grid energy storage devices are critical for the success of the clean and sustainable energy revolution. As Li-ion batteries are earmarked for electric vehicles and portable devices such as laptops and cellphones, other electrochemical systems should be developed that enable cost-effective, safe, and durable large-scale energy storage. Due to the low cost and non-flammability of aqueous electrolyte solutions, much effort is being put into the development of ‘beyond-Li’ batteries and super capacitors that can work in these environments. Here, we propose new proton batteries comprising an acetic acid electrolyte solution, NiII [FeIII(CN)6]2/3·4H2O Prussian blue analog cathodes, and Ti3C2Tx MXene anodes. Both electrodes were investigated independently to discover ideal settings for the electrochemical performance and stability. Significant attention was given to the cathodes' protons storage mechanism. In-situ electrochemical quartz crystal microbalance with dissipation revealed that in acetic acid, hydronium and proton insertion contribute to charge storage, whereas in sulfuric acid-based electrolyte solutions, the main charge carriers are bare protons. 4.5 M acetic acid solution provided the best performance in terms of electrodes' capacitance and rate capability. The battery systems presented here show a promising direction but require further intensive optimization efforts. This research opens the way for research and development of novel proton batteries based on solutions containing common weak acids for more cost-effective and environmentally friendly energy storage systems.

Branched Glucan from Leuconostoc Mesenteroides as the channel for ionic migration in the fabrication of protonic (H+) battery

This research paper reports the characteristics of dextran-glycerol-ammonium hexafluorophosphate (NH4PF6) electrolyte system and application in proton batteries. The solid polymer electrolyte films are obtained by solution cast method. Interaction between dextran, glycerol and NH4PF6 salt is examined using Fourier transform infrared spectroscopy (FTIR) analysis. Electrolyte with 18 wt.% NH4PF6 exhibits the highest room temperature conductivity of (1.43 ± 0.16) × 10−4 S cm−1. It is inferred that the conductivity is mainly controlled by the changes in ionic mobility and diffusion coefficient. Field emission scanning electron microscopy (FESEM) analysis shows the difference in the morphology with respect to NH4PF6 content and verifies the conductivity result. Differential scanning calorimetry (DSC) analysis confirms that the presence of plasticizer and 18 wt.% salt has decreased the glass transition temperature (Tg). The temperature dependence of conductivity for the highest conducting electrolyte shows a typical Vogel-Tamman-Fulcher (VTF) behavior. The proton batteries have been discharged at different constant currents.

Redox‐Active Polymer Integrated with MXene for Ultra‐Stable and Fast Aqueous Proton Storage

AbstractProton is a charge carrier with the smallest ionic size and quickest kinetics, making aqueous proton batteries (APBs), a promising technology for safe and profitable energy storage systems. Despite being potential electrode materials, organic compounds have not yet been fully investigated in terms of proton storage properties and APB applications due to their low capacity and unstable cycle life in aqueous electrolytes. Herein, a novel redox‐active polymer (PDPZ) with diquinoxalino‐phenazine as the structural unit has been designed, which is further integrated with MXene nanosheets to construct a flexible PDPZ@MXene electrode material with a rapid and ultra‐stable proton storage behavior. In‐operando monitoring techniques, i.e., in situ Raman and in situ FTIR, demonstrate the highly reversible redox reaction between CN and CN/NH bonds in electro‐active PDPZ molecule with the strong proton absorption ability. Theoretical calculation further proves the electron transfer from MXene to PDPZ promotes the redox reaction of the PDPZ@MXene electrode. As a result, a flexible APB device is developed with a considerable energy density (64.3 mWh cm−3), a supercapacitor‐level power density (6000 mW cm−3), and a record lifespan with ≈98.2% capacity retention over 10 000 cycles, revealing its potential applications in satisfying the various requirements of energy storage systems.

Development of MoO3-Based Proton Batteries

Aqueous rocking chair batteries have attracted attention as highly safe and inexpensive secondary batteries. Lithium and sodium ions have mostly been used as the mobile ions, whereas proton systems with potentially the highest mobility have rarely been reported. Recently, research on proton batteries has been conducted using concentrated sulfuric acid solutions as the electrolyte that can assist high-rate performance.[1] Stability under concentrated acidic conditions is required for the electrode materials, as well as the capability of proton accommodation. MoO3 has been reported as a stable negative electrode material for aqueous proton batteries,[2] while few positive electrode materials are known except for bulky organic[3] and Prussian-blue materials[4]. For achieving high energy density and long life, oxide positive electrode materials are desirable. Here we propose the application of MoO3 as the positive electrode material by optimizing the operating composition range. The potential values shown below are all shown versus SHE (actually measured with Ag/AgCl).MoO3 showed a discharge profile at around 0.5 V with the maximum capacity of ca. 100 mAh g-1, as shown in the figure. This potential is sufficiently more positive than the redox potential of protonated MoO3 of around -0.3 V as the negative electrode. With the aid of operando X-ray diffraction analysis, it turned out that the discharge regions at 0.5 V and 0.4 V are respectively associated with a biphasic transition of MoO3/phase I (ca. 0 < x < 0.3 in H x MoO3) and a single-phase reaction of phase I (ca. 0.3 < x < 0.5 in H x MoO3). Deep discharging beyond this range results in the coexistence of phase I and phase III (ca. 0.5 < x < 1.5 in H x MoO3) and the proton extraction from phase III leads to the formation of phase II or phase IIa with its discharging potential of 0.0 V. Structural calculation based on the density function theory is employed to clarify the origin of this irreversible phase transition behavior. Different proton sites between these phases seem to be responsible.An aqueous proton battery with a 7 mol dm–3 sulfuric acid electrolyte was constructed with H-inserted MoO3 and MoO3as the negative and positive electrodes, respectively, and was successfully discharged and charged repeatedly, with the operating voltage of ca. 0.6 V, indicating the launch of aqueous proton battery composed of oxide active materials. Reference s : [1] J. Li, H. Yan, C. Xu, Y. Liu, X. Zhang, M. Xia, L. Zhang, J. Shu, Nano Energy, 89 (2021) 106400.[2] X. Wang, Y. Xie, K. Tang, C. Wang, C. Yan, Angew. Chem. Int. Ed., 57 (2018) 11569.[3] X. Wang, J. Zhou, W. Tang, Energy Storage Mater., 36 (2021) 1.[4] X. Wu, J. J. Hong, W. Shin, L. Ma, T. Liu, X. Bi, Y. Yuan, Y. Qi, T. W. Surta, W. Huang, J. Neuefeind, T. Wu, P. A. Greaney, J. Lu, X. Ji, Nat. Energy, 4 (2019) 123. Figure 1

Insights on the proton mechanism in carbonyl-based organic electrode of neutral aqueous battery

Implementing proton insertion/removal in an aqueous battery has advantages like high safety, high rate, and low-temperature properties. The proton energy storage materials are mainly based on inorganic material in a strong acid electrolyte. Proton batteries attract much attention under neutral condition, especially based on the metal-free organic electrode. However, the proton concentration of neutral electrolyte is very low, and the proton insertion mechanism is not well understood. Herein, we firstly uncover the special energy storage mechanism of carbonyl materials as proton acceptor in neutral electrolyte. Carbonyl groups adsorb water molecular and induce proton insertion, this diffusion-free mechanism determines its fast reaction kinetics, which helps to improve the power density. Released OH− during proton insertion creates a local alkaline environment, which broadens the electrochemical window and contributes to the high energy density. With the structural diversity and tunability of carbonyl group, this special mechanism indicates that carbonyl-based organic materials are potential electrode for low-cost and high-performance neutral aqueous battery in the future.

Molecular Crowding Electrolytes for Stable Proton Batteries.

Proton electrochemistry is promising for developing post-lithium energy storage devices with high capacity and rate capability. However, some electrode materials are vulnerable because of the co-intercalation of free water molecules in traditional acid electrolytes, resulting in rapid capacity fading. Here, the authorsreport a molecular crowding electrolyte with the usage of poly(ethylene glycol) (PEG) as a crowding agent, achieving fast and stable electrochemical proton storage and expanded working potential window (3.2V). Spectroscopic characterisations reveal the formation of hydrogen bonds between water and PEG molecules, which is beneficial for confining the activity of water molecules. Molecular dynamics simulations confirm a significant decrease of free water fraction in the molecular crowding electrolyte. Dynamic structural evolution of the MoO3 anode is studied by in-situ synchrotron X-ray diffraction (XRD), revealing a reversible multi-step naked proton (de)intercalation mechanism. Surficial adsorption of PEG molecules on MoO3 anode works in synergy to alleviate the destructive effect of concurrent water desolvation, thereby achieving enhanced cycling stability. This strategy offers possibilities of practical applications of proton electrochemistry thanks to the low-cost and eco-friendly nature of PEG additives.

Proton Storage in Metallic H1.75MoO3 Nanobelts through the Grotthuss Mechanism.

The proton, as the cationic form of the lightest element-H, is regarded as most ideal charge carrier in "rocking chair" batteries. However, current research on proton batteries is still at its infancy, and they usually deliver low capacity and suffer from severe acidic corrosion. Herein, electrochemically activated metallic H1.75MoO3 nanobelts are developed as a stable electrode for proton storage. The electrochemically pre-intercalated protons not only bond directly with the terminal O3 site via strong O-H bonds but also interact with the oxygens within the adjacent layers through hydrogen bonding, forming a hydrogen-bonding network in H1.75MoO3 nanobelts and enabling a diffusion-free Grotthuss mechanism as a result of its ultralow activation energy of ∼0.02 eV. To the best of our knowledge, this is the first reported inorganic electrode exhibiting Grotthuss mechanism-based proton storage. Additionally, the proton intercalation into MoO3 with formation of H1.75MoO3 induces strong Jahn-Teller electron-phonon coupling, rendering a metallic state. As a consequence, the H1.75MoO3 shows an outstanding fast charging performance and maintains a capacity of 111 mAh/g at 2500 C, largely outperforming the state-of-art battery electrodes. More importantly, a symmetric proton ion full cell based on H1.75MoO3 was assembled and delivered an energy density of 14.7 Wh/kg at an ultrahigh power density of 12.7 kW/kg, which outperforms those of fast charging supercapacitors and lead-acid batteries.

Designing Quinone‐Based Anodes with Rapid Kinetics for Rechargeable Proton Batteries

AbstractQuinone compounds, which are capable of accommodating proton (H+), are emerging electrodes in aqueous batteries. However, the storage mechanism of proton in quinone compounds is less known and the energy/power density of quinone‐based proton battery is still limited. Here we design a series of quinone anodes and study their electrochemical properties in acidic electrolyte, in which tetramethylquinone (TMBQ) delivers a high capacity of 300 mAh g−1 with an extremely low polarization of 20 mV at 1 C, and maintains over 50 % theoretical capacity in less than 16 seconds. The fast kinetics of TMBQ is attributed to the continuous H+ migration channel, high H+ diffusion coefficient (10−6 cm2 s−1), and low H+ migration energy barrier (0.26 eV). When coupling with MnO2 cathode, the battery shows a long lifespan of 4000 cycles with a capacity retention of 77 % at 5 C. This study reveals the proton transport in quinone‐electrodes and offers new insights to design advanced aqueous batteries.

Designing Quinone-Based Anodes with Rapid Kinetics for Rechargeable Proton Batteries.

Quinone compounds, which are capable of accommodating proton (H+ ), are emerging electrodes in aqueous batteries. However, the storage mechanism of proton in quinone compounds is less known and the energy/power density of quinone-based proton battery is still limited. Here we design a series of quinone anodes and study their electrochemical properties in acidic electrolyte, in which tetramethylquinone (TMBQ) delivers a high capacity of 300 mAh g-1 with an extremely low polarization of 20 mV at 1 C, and maintains over 50 % theoretical capacity in less than 16 seconds. The fast kinetics of TMBQ is attributed to the continuous H+ migration channel, high H+ diffusion coefficient (10-6 cm2 s-1 ), and low H+ migration energy barrier (0.26 eV). When coupling with MnO2 cathode, the battery shows a long lifespan of 4000 cycles with a capacity retention of 77 % at 5 C. This study reveals the proton transport in quinone-electrodes and offers new insights to design advanced aqueous batteries.

A Proton Battery Stack Real-Time Monitor with a Flexible Six-in-One Microsensor.

A proton battery is a hybrid battery produced by combining a hydrogen fuel cell and a battery system in an attempt to obtain the advantages of both systems. As the battery life of a single proton battery is not good, the proton battery stack is developed by connecting in parallel, which can greatly improve the battery life of proton batteries. In order to obtain important information about the proton battery stack in real time, a flexible six-in-one microsensor is embedded in the proton battery stack. This study has successfully developed a health diagnostic tool for a proton battery stack using micro-electro-mechanical systems (MEMS) technology. This study also focused on the innovatively developed hydrogen microsensor, and integrated the voltage, current, temperature, humidity, and flow microsensors, as previously developed by our laboratory, to complete the flexible six-in-one microsensor. Six important internal physical parameters were simultaneously measured during the entire operation of the proton battery stack. It also established a complete database and monitor system in real time to detect the internal health status of the proton cell stack and observe if there were problems, such as water accumulation, aging, or failure, in order to understand the changes and effects of the various physical quantities of long-term operation. The study found that the proton batteries exhibited significant differences in the hydrogen absorb rates and hydrogen release rates. The ceramic circuit board used in the original sensor is replaced by a flexible board to improve problems such as peeling and breaking.

In-situ Raman investigation and application of phenazine-based organic electrode in aqueous proton batteries

Aqueous proton batteries (APBs) have aroused attention because of the proton as charge carrier with smaller ionic size and faster kinetics when compared to the metallic ions in aqueous solutions. Although phenazine-based organic compounds with available redox-active sites are considered as promising organic electrode materials, the comprehensive study of their proton-storage behaviors and APB applications is still lacking so far. Herein, a rod-like diquinoxalino-phenazine (DPZ) organic compound is designed and synthetized via a facile dehydration approach. In-situ Raman investigation and theoretical calculation are conducted to probe into the proton redox process of DPZ organic electrode for the first time. It is demonstrated that three CN electroactive regions in each DPZ molecular unit could be simultaneously coordinated with two protons and the redox reaction between CN and CN bonds is highly reversible upon proton insertion/extraction. As expected, the DPZ organic electrode delivers a large proton-storage capacity of ∼ 218 mAh/g and long-term cycle performance without obvious dissolubility in acidic aqueous electrolyte. For real applications, soft-package and wire-shaped APBs based on such DPZ organic electrode are constructed, and they both achieve outstanding electrochemical characteristics, revealing their great potential applications in low-cost, high-safety, and high-performance energy technologies and portable/wearable electronics.

Performance of a fuel cell‐based proton battery with varied designs of micro‐flow channel for enhanced hydrogen storage

AbstractWe present an experimental investigation on a proton battery, that could run both as electrolyser and fuel cell, using six different flow channel orientations viz. pin‐type, parallel, interdigitated, spiral, serpentine, and parallel serpentine. The battery stores energy in the form of hydrogen ions and its performance is determined in terms of hydrogen wt. % stored in an integrated carbon‐based electrode. In this paper, the fabrication of electrode, development of an experimental proton battery and its testing are disclosed. The characterization of the employed activated carbon electrode is done using scanning electron microscopy, X‐ray diffraction analysis, energy dispersive spectroscopy, and fourier transform infrared spectroscopy. The fabricated proton battery is tested by charging (E‐mode operation) and discharging (FC‐mode operation) subsequently at normal temperature and pressure conditions. In the E‐mode operation, electrochemical hydrogen storage of the battery with six different flow channels is found to be in the range of 1.36–1.97 wt. %. The corresponding desorption of hydrogen in the FC‐mode operation is found to be in the range of 1.047–1.479 wt. %, respectively, for six different flow channels. The comparative result analysis revealed that parallel serpentine flow channel outperformed, with energy storage capacity of 1.97 wt. %; and pin type channel design showed comparatively low performance with energy storage capacity of 1.36 wt. %. The presented research work is an effort towards meeting the set targets of hydrogen storage set by the U.S. Department of Energy to make the hydrogen technology commercially viable.Statement of Industrial RelevanceThe presented research work has relevance with the power industry as it reveals the optimum design of flow channels for enhanced hydrogen adsorption. It is a way forward towards developing a fuel‐cell based proton battery that does not emit harmful fumes like lithium batteries and therefore, is environmentally friendly.Novelty or SignificanceThe presented research work is a maiden attempt of testing different designs of micro‐flow channels in an experimental proton battery that is a single unit capable of performing dual tasks i.e., electrolyser and fuel cell to store energy and give out power when required.

Stable colloid-in-acid electrolytes for long life proton batteries

The emerging proton electrochemistry offers opportunities for future energy storage of high capacity and rate. However, the development of proton batteries is hindered by low working-potentials of electrodes and poor cycle life of full-cells (e.g., tens-of-hours). The high-potential MnO2/Mn2+ redox couple presents a facile and competitive cathode choice, typically via electrodepositing solids on substrates for energy storage. Herein, we show the formation of homogeneous and stable MnO2 colloids from the Mn2+ electrolysis in H2SO4 (≥ 1.0 M), and their application to achieve long life proton batteries. Colloid electrolytes enable prolonged cycling of a MnO2//MoO3 cell from 11.7 h to 33 days, and a MnO2//pyrene-4,5,9,10-tetraone cell for 489days, which is the longest duration ever reported for proton batteries. Comprehensive analysis shows the colloid particle is mainly a MnO2 nucleus coordinated by electrolyte ions of hydrated Mn2+, Mn3+, H+ and SO42-. Through water dilution, solid components of colloids precipitate into hierarchical nanosheet spheres; Further characterizations of the precipitates and deposited substrates reveal ε-MnO2 as the major electrolytic product regardless of electrolytes used. Different colloids could reform from precipitates depending on presence/absence of Mn2+ in acids, suggesting colloid balances include both physical and chemical interactions. Our findings of the new chemistry for the MnO2/Mn2+ electrolysis are also anticipated to underlie a range of novel aqueous energy storage.

Anhydrous Fast Proton Transport Boosted by the Hydrogen Bond Network in a Dense Oxide-Ion Array of α-MoO3.

Developing high-power battery chemistry is an urgent task to buffer fluctuating renewable energies and achieve a sustainable and flexible power supply. Owing to the small size of the proton and its ultrahigh mobility in water via the Grotthuss mechanism, aqueous proton batteries are an attractive candidate for high-power energy storage devices. Grotthuss proton transfer is ultrafast owing to the hydrogen-bonded networks of water molecules. In this work, similar continuous hydrogen bond networks in a dense oxide-ion array of solid α-MoO3 are discovered, which facilitate the anhydrous proton transport even without structural water. The fast proton transfer and accumulation that occurs during (de)intercalation in α-MoO3 is unveiled using both experiments and first-principles calculations. Coupled with a zinc anode and a superconcentrated Zn2+ /H+ electrolyte, the proton-transport mechanism in anhydrous hydrogen-bonded networks realizes an aqueous MoO3 -Zn battery with large capacity, long life, and fast charge-discharge abilities.