Low Potential Anode Research Articles

A Molten Alkali Approach to Tailor Hydroxyl Groups of Hexaazatrinaphthalene Toward High-Capacity and Low-Potential Anode of Aqueous Proton Batteries.

Hexaazatrinaphthalene (HATN) has attracted a lot of attention in aqueous proton batteries (APBs). However, its redox potential as an anode is insufficiently negative. The introduction of electron-donating substituent groups, such as hydroxyl groups, is considered as a good approach to reduce the redox potential of HATN. Nevertheless, manufacturing hydroxyl-substituted HATN (HATN-OH) requires either expensive precursors or multi-step process, limiting their research. Herein, a straightforward strategy is proposed to synthesize HATN-OH based on the nucleophilic substitution reaction of halogenated HATN in a molten alkali. The redox potential of 1,2,7,8,13,14-hexahydroxy-5,6,11,12,17,18-hexaazatrinaphthalene (34-HATN-6OH) electrode may be lowered by 0.15V in comparison to HATN, and exhibits a high specific capacity, low redox potential, remarkable rate capability, and outstanding long-term cycling performance. The electrochemical redox kinetics is significantly enhanced owing to the formation of rapid proton transport channels created by intermolecular hydrogen bond network. The assembled MnO2||34-HATN-6OH full battery delivers a high discharge voltage (1.16V) and cycling stability (74% capacity retention after 5000 cycles). This study provides a general cost-effective molten alkali approach for the synthesis of hydroxyl-substituted conjugated small molecules from their halogenated counterparts and further enriches the regulation means of electro-chemical performances of organic electrodes for enabling high-capacity and high-voltage APBs.

A Pyrazine‐Pyridinamine Covalent Organic Framework as a Low Potential Anode for Highly Durable Aqueous Calcium‐Ion Batteries (Adv. Energy Mater. 1/2024)

A Pyrazine‐Pyridinamine Covalent Organic Framework as a Low Potential Anode for Highly Durable Aqueous Calcium‐Ion Batteries (Adv. Energy Mater. 1/2024)

High-Reversibility Sulfur Anode for Advanced Aqueous Battery.

Despite being extensively explored as cathodes in batteries, sulfur (S) can function as a low-potential anode by changing charge carriers in electrolytes. Here, a highly reversible S anode that fully converts from S8 0 to S2- in static aqueous S-I2 batteries by using Na+ as the charge carrier is reported. This S anode exhibits a low potential of -0.5V (vs standard hydrogen electrode) and a near-to-theoretical capacity of 1404mA h g-1 . Importantly, it shows significant advantages over the widely used Zn anode in aqueous media by obviating dendrite formation and H2 evolution. To suppress "shuttle effects" faced by both S and I2 electrodes, a scalable sulfonated polysulfone (SPSF) membrane is proposed, which is superior to commercial Nafion in cost (US$1.82 m-2 vs $3500 m-2 ) and environmental benignity. Because of its ultra-high selectivity in blocking polysulfides/iodides, the battery with SPSF displays excellent cycling stability. Even under 100% depth of discharge, the battery demonstrates high capacity retention of 87.6% over 500 cycles, outperforming Zn-I2 batteries with 3.1% capacity under the same conditions. These findings broaden anode options beyond metals for high-energy, low-cost, and fast-chargeable batteries.

A Pyrazine‐Pyridinamine Covalent Organic Framework as a Low Potential Anode for Highly Durable Aqueous Calcium‐Ion Batteries

AbstractRechargeable aqueous calcium‐ion batteries (CIBs) are promising for reliable large‐scale energy storage. However, they face significant challenges, primarily stemming from suboptimal anodes, resulting in unfavorable voltage profiles, limited capacity, and diminished durability, all of which hinder the development of CIBs. Here, a covalent organic framework (PTHAT‐COF) featuring repeated pyrazine and pyridinamine units, employed as the anode material for aqueous CIBs, is introduced. This innovative approach results in a remarkably flat ultralow potential plateau ranging from −0.6 to −1.05 V (vs Ag/AgCl), attributed to the high level of the lowest unoccupied molecular orbital. Furthermore, the PTHAT‐COF anode exhibits outstanding rate performance (152.3 mAh g−1 @ 1 A g−1), exceptional long‐term cycling stability, and remarkable capacity retention (10 000 cycles with 89.9% retention). Mechanistic studies, including experimental and theoretical calculations, reveal that C═N active sites reversibly trap Ca2+ ions via chemisorption during the discharging/charging process. The PTHAT‐COF demonstrates exceptional structural stability throughout cycling. Finally, by pairing PTHAT‐COF with a high‐voltage manganese‐based Prussian blue cathode, a complete aqueous CIB with a voltage interval of 2.2 V is achieved, exhibiting extraordinary durability (10 000 cycles with 83.6% retention). This research illuminates the potential of organic anode materials in aqueous batteries to achieve higher battery voltages.

Uncovering the Redox Shuttle Degradation Mechanism of Ether Electrolytes in Sodium-Ion Batteries and its Inhibition Strategy.

Ether-based electrolytes exhibit excellent performance when applied in different anode materials of sodium ion batteries (SIBs), but their exploration on cathode material is deficient and the degradation mechanism is still undiscovered. Herein, various battery systems with different operation voltage ranges are designed to explore the electrochemical performance of ether electrolyte. It is found for the first time that the deterioration mechanism of ether electrolyte is closely related to the "redox shuttle" between cathode and low-potential anode. The "shuttle" is discovered to occur when the potential of anodes is below 0.57V, and the gas products coming from "shuttle" intermediates are revealed by differential electrochemical mass spectrometry (DEMS). Moreover, effective inhibition strategies by protecting low-potential anodes are proposed and verified; ethylene carbonate (EC) is found to be very effective as an additive by forming an inorganics-rich solid electrolyte interphase (SEI) on low-potential anodes, thereby suppressing the deterioration of ether electrolytes. This work reveals the failure mechanism of ether-based electrolytes applied in SIBs and proposes effective strategies to suppress the "shuttle," which provides a valuable guidance for advancing the application of ether-based electrolytes in SIBs.

Layered Li–Co–B as a Low-Potential Anode for Lithium-Ion Batteries

An anode material is one of the key factors affecting the capacity, cycle, and rate (fast charge) performance of lithium-ion batteries. Using the adaptive genetic algorithm, we found a new ground-state Li2CoB and two metastable states LiCoB and LiCo2B2 in the Li-Co-B system. The Li2CoB phase is a lithium-rich layered structure, and it has an equivalent lithium-ion migration barrier (0.32 eV) in addition to the lower voltage platform (0.05 V) than graphite, which is the most important commercial anode material at present. Moreover, we analyzed the mechanism of delithiation for Li2CoB and found that it maintained metallicity in the process of delithiation, indicating its good conductivity as an electrode material. Therefore, it is an excellent potential anode material for lithium-ion batteries. Our work provides a promising theoretical basis for the experimental synthesis of Li-Co-B and similar new materials.

Intracytoplasmic membranes develop in Geobacter sulfurreducens under thermodynamically limiting conditions

Geobacter sulfurreducens is an electroactive bacterium capable of reducing metal oxides in the environment and electrodes in engineered systems1,2. Geobacter sp. are the keystone organisms in electrogenic biofilms, as their respiration consumes fermentation products produced by other organisms and reduces a terminal electron acceptor e.g. iron oxide or an electrode. To respire extracellular electron acceptors with a wide range of redox potentials, G. sulfurreducens has a complex network of respiratory proteins, many of which are membrane-bound3–5. We have identified intracytoplasmic membrane (ICM) structures in G. sulfurreducens. This ICM is an invagination of the inner membrane that has folded and organized by an unknown mechanism, often but not always located near the tip of a cell. Using confocal microscopy, we can identify that at least half of the cells contain an ICM when grown on low potential anode surfaces, whereas cells grown at higher potential anode surfaces or using fumarate as electron acceptor had significantly lower ICM frequency. 3D models developed from cryo-electron tomograms show the ICM to be a continuous extension of the inner membrane in contact with the cytoplasmic and periplasmic space. The differential abundance of ICM in cells grown under different thermodynamic conditions supports the hypothesis that it is an adaptation to limited energy availability, as an increase in membrane-bound respiratory proteins could increase electron flux. Thus, the ICM provides extra inner-membrane surface to increase the abundance of these proteins. G. sulfurreducens is the first Thermodesulfobacterium or metal-oxide reducer found to produce ICMs.

Meticulous integration of N and C active sites in Ni2P electrocatalyst for sustainable ammonia oxidation and efficient hydrogen production

Ammonia, as an efficient hydrogen carrier, is emerging as an alternative energy resource to replace fossil fuels in the carbon–neutral era. Hydrogen production by water electrolysis seeks a lower potential dependent anodic reaction to overcome its energy-inefficiency that originates from the high potential anodic oxygen evolution reaction (OER). In this work, nickel phosphide supported on nitrogen doped-carbon (Ni2P@N-C) was prepared by one-pot synthesis for the bifunctional activity of hydrogen evolution (HER) and ammonia oxidation (AOR) reactions. The Ni2P@N-C electrocatalyst exhibits about 78% decomposition of ammonia compared to the initial concentration. The amount of hydrogen generated in a 0.5 M ammonia environment for 30 min is about 2.144 mmol(H2)/mol(NH3) h cm2. The fabricated ammonia electrolysis cell demonstrates a comparatively low energy consumption rate of 8.611 KWHkg(H2)−1. Thus, engineering a bifunctional electrocatalyst for a low potential anode oxidation reaction and the cathodic HER is a promising strategy to fabricate an energy efficient electrolysis cell for hydrogen production with a low cell potential requirement.

Low-potential solid-solid interfacial charging on layered polyaniline anode for high voltage pseudocapacitive intercalation Li-ion supercapacitors

Lithium-ion supercapacitors (LISCs) have attracted increasing attention for its competitive energy and power capabilities compared with electric double layer capacitors and lithium-ion batteries. The working voltage of LISCs is the potential difference between the cathode and the anode and is oftentimes determined by the lower potential limit of the anode. Up to date, only carbon and MXene anodes can allow charge/discharge at low potentials. Here, we report electrochemically tuned layered polyaniline with solidified SEI nanochannels that promises as new type low potential anode for high voltage pseudocapacitive intercalation LISCs (PI-LISCs). We found that the tuned layered polyaniline attained high volumetric capacity of 196 mAh cm−3 at 25 mA g−1 at potentials as low as 0.01 V vs. Li/Li+, while allows the fabrication of a high voltage PI-LISC at 4.5 V with a high energy density of 100.5 Wh L−1 at 219.8 W L−1 and a high power density of 13.7 kW L−1 at 27.9 Wh L−1, as well as excellent capacity retention at 90.1 % after 10,000 cycles. Our findings present a significant step forward to open up new opportunities of high energy and high power PI-LISCs.

Recent Progress and Perspective: Na Ion Batteries Used at Low Temperatures.

With the rapid development of electric power, lithium materials, as a rare metal material, will be used up in 50 years. Sodium, in the same main group as lithium in the periodic table, is abundant in earth’s surface. However, in the study of sodium-ion batteries, there are still problems with their low-temperature performance. Its influencing factors mainly include three parts: cathode material, anode material, and electrolyte. In the cathode, there are Prussian blue and Prussian blue analogues, layered oxides, and polyanionic-type cathodes in four parts, as this paper discusses. However, in the anode, there is hard carbon, amorphous selenium, metal selenides, and the NaTi2(PO4)3 anode. Then, we divide the electrolyte into four parts: organic electrolytes; ionic liquid electrolytes; aqueous electrolytes; and solid-state electrolytes. Here, we aim to find electrode materials with a high specific capacity of charge and discharge at lower temperatures. Meanwhile, high-electrical-potential cathode materials and low-potential anode materials are also found. Furthermore, their stability in air and performance degradation in full cells and half-cells are analyzed. As for the electrolyte, despite the aspects mentioned above, its electrical conductivity in low temperatures is also reported.

Electrochemical Behavior of CsI in LiCl Molten Salt

The electrochemical behavior of CsI in LiCl molten salt was investigated to identify its impact on the electrolytic oxide reduction of oxide-phase spent nuclear fuels by combined electrolysis and cyclic voltammetry experiments of LiCl-CsI in comparison with LiCl, LiCl-CsCl, and LiCl-LiI. It was found that Cs+ ions were hardly involved in the cathode reaction, and reduction of Li+ ions occurred dominantly in the cathode. In contrast, incorporation of I− ions induced low-potential anode reaction compared with the I− ion-free cases. Such additional electrochemical reaction resulted in the generation of I2 and/or ICl gases, which would increase a process burden for treating 129I with exceptionally long lifetime. In this respect, separating CsI from spent nuclear fuel before the electrolytic oxide reduction is recommended for the purpose of efficient waste management.

A disordered rock salt anode for fast-charging lithium-ion batteries

Rechargeable lithium-ion batteries with high energy density that can be safely charged and discharged at high rates are desirable for electrified transportation and other applications1-3. However, the sub-optimal intercalation potentials of current anodes result in a trade-off between energy density, power and safety. Here we report that disordered rock salt4,5 Li3+xV2O5 can be used as a fast-charging anode that can reversibly cycle two lithium ions at an average voltage of about 0.6 volts versus a Li/Li+ reference electrode. The increased potential compared to graphite6,7 reduces the likelihood of lithium metal plating if proper charging controls are used, alleviating a major safety concern (short-circuiting related to Li dendrite growth). In addition, a lithium-ion battery with a disordered rock salt Li3V2O5 anode yields a cell voltage much higher than does a battery using a commercial fast-charging lithium titanate anode or other intercalation anode candidates (Li3VO4 and LiV0.5Ti0.5S2)8,9. Further, disordered rock salt Li3V2O5 can perform over 1,000 charge-discharge cycles with negligible capacity decay and exhibits exceptional rate capability, delivering over 40 per cent of its capacity in 20 seconds. We attribute the low voltage and high rate capability of disordered rock salt Li3V2O5 to a redistributive lithium intercalation mechanism with low energy barriers revealed via ab initio calculations. This low-potential, high-rate intercalation reaction can be used to identify other metal oxide anodes for fast-charging, long-life lithium-ion batteries.

Titanosilicate Sitinakite Compound As a Low-Potential Anode for Sodium-Ion Battery

Sodium-ion batteries (SIBs) have been considered as a promising candidate for large-scale energy storage applications, because of the low cost of sodium element and a broad choice of cathode materials which do not contain the expensive raw materials. However, a lack of promising anode materials still hinders the development of SIBs technology. Herein, we for the first time report a one dimensional tunnel-structure titanosilicate sitinakite compound with an ideal formula of Na1.68H0.32Ti2O3SiO4·1.76H2O employed as a new type anode material in SIBs. This material can deliver a reversible capacity of 110 mAh g-1 at a current density of 20 mA g-1 and with an average working voltage of 0.4 V vs. Na+/Na. The structure changes of this material during discharge/charge processes were investigated by using in-situ laboratory X-ray diffraction. The results indicated that sodium insertion proceeds via a topotactic intercalation pathway. We also identified pre-dehydration as an effective avenue to further improve the capacity of Na1.68H0.32Ti2O3SiO4·1.76H2O anode (reversible capacity of 131 mAh g-1 at a current density of 20 mA g-1 after pre-dehydration process). In addition, cation Nb doped Na1.68H0.32Ti2O3SiO4·1.76H2O compounds have been synthesized and systematically investigated the electrochemical performances in SIBs. Reference [1] Liu, Y.; Xia, Y., Na1.68H0.32Ti2O3SiO4·1.76H2O as a Low-Potential Anode Material for Sodium-Ion Battery. ACS Applied Energy Materials 2018, doi:10.1021/acsaem.8b01412.

Direct Experimental Observation of the Interfacial Instability of the Fast Ionic Conductor Li10GeP2S12 at the Lithium Metal Anode

High capacity and low potential anode materials like lithium metal are preferred for high energy densities in all solid-state batteries. Due to the highly reducing potential of lithium metal, the electrochemical and thermodynamic stability of a solid ion conductor at the interface plays a crucial role for the performance of all solid-state batteries. When a solid electrolyte is in contact with lithium metal, three different types of interfaces may occur:1 (I) A stable interface may form with electrolytes that are thermodynamically stable against Li contact. (II) A reaction occurs and a mixed ionic-electronic conducting (MCI) new interphase forms,2 which rapidly growths due to the electronic percolation pathways. (III) A reaction occurs and a solid electrolyte interphase (SEI) forms,3 which only conducts ions. While (I) may be preferred and (II) is exclusively detrimental, due to a proceeding reaction front, the impact of (III) on the battery performance depends on the type of forming SEI. Here we will shortly introduce the types of possible interphases/interfaces and discuss the expected effects on the overall resistance and performance of an all-solid-state battery. Using time-resolved impedance spectroscopy and time-resolved cyclic voltammetry we introduce a guideline to characterize solid electrolytes for their stability against metal interfaces. The solid electrolyte Li10GeP2S12 will be shown as an example of an instability,4 as has been theoretically predicted.5,6 SEI formation occurs, affecting the overall cell resistance detrimentally. Using a novel in situ X-ray photoelectron technique we study the resulting interphase formation when Li10GeP2S12 is in contact with Li. Using the observed chemical species, in combination with time-resolved electrochemical measurements, we suggest a reaction mechanism for the interphase formation as well as provide an understanding of the growth kinetics. 1Wenzel S., Leichtweiss T., Krüger D., Sann J., Janek J. Solid State Ion. 2015, 278, 98-105 2Hartmann P., Leichtweiss T., Busche M., Schneider M., Reich M., Sann J., Adelhelm P., Janek J. J. Phys. Chem. C 2013, 117, 21064-21074 3 Wenzel S., Weber D., Leichtweiss T., Busche M., Sann J., Janek J. Solid State Ion. 2016, 286, 24-33 4Wenzel S., Randau S., Leichtweiss T., Weber D., Sann J., Zeier W.G., Janek J. submitted 5Zhu Y., He X., Mo Y. ACS Appl. Mater. Int. 2015, 7, 23685-23693 6Zhu Y., He X., Mo Y. J. Mater. Chem A 2016 DOI: 10.1039/C5TA08574H.

Development of Sulfolane-Based Electrolytes for Li-ion batteries

The quest for higher energy density Li-ion batteries pushes toward ‘high voltage’ cathode operating above 4.5V. However, if such materials have been proposed for many years in the case of LiNi0.5 Mn1.5 O4 1 or more recently for LiCoPO4F2, the implementation of such materials is currently prevented by the lack of adapted electrolyte. Several reports deal with high voltage electrolytes such as ionic liquids, dinitrile compounds or fluorinated carbonates. Yet, another class of solvents investigated are the alkyl sulfone, linear3 or cyclic4. Among them, sulfolane, despites its high viscosity has been reported to allow low potential anode operation (such as Li metal or graphite), while other reports point out the high oxidative stability of the electrolytes made thereof4, which was explained based on fundamental studies such as QC5 and MD6. Mixtures of sulfolane seem able to allow room temperature operation of both graphite and high voltage electrodes but no report can be found of a sulfolane-based electrolyte compatible, at the same time, with graphite and a high voltage electrodes. Thus, we examine here the possibility of forming new electrolyte system, based on sulfolane/DMC mixtures for room temperature operation. In particular, the role of the Li salt has been investigated as it is known to play a role on conductivity, via viscosity and dissociation in a solvent system that has a lower dielectric constant and higher viscosity than alkyl carbonate mixtures such as EC/DMC. In addition, keeping the application in mind, SEI building on graphite and aluminum current collector corrosion are also dependent on the Li salt or mixture used. Thus several inorganic and organic Li salts have been investigated in terms of conductivity and electrochemical stability and tested versus graphite and LiNi0.5 Mn1.5 O4 electrodes in a DMC/sulfolane mixed solvent.

The Low Potential Zinc Anode In Theory and Application

Abstract After a brief discussion of the principles of cathodic protection and the basic requirements of a galvanic anode, anode requirements are examined specifically in terms of the cathodic protection of iron or steel in an electrolyte of uniform characteristics. For sea water it is shown that it is desirable to limit the cathode polarization to a value less anodic than −1.1 v (vs Ag/AgCl). The advantages of a low potential anode for the cathodic protection of iron under these conditions are discussed in detail in terms of circuit resistance, self-regulation, and cunrent distribution on the cathode. Other desirable anode characteristics such as current efficiency, current capacity per unit volume, and the effect of anode shape on anode current output are examined mathematically. The practical advantages and implications of the above considerations are described. It is suggested that where cathode polarization controls current distribution on the cathode and regulates anode current output, a new concept can be advanced for the design of cathodic protection systems utilizing low potential zinc anodes. 5.2.2