Secondary Zinc-air Batteries Research Articles

Strong electronic coupling between Ni-based MOF and Ni2P enables high-efficiency oxygen evolution reaction for various application scenarios

The high overpotential and sluggish kinetics of oxygen evolution reaction (OER) severely hinder the widespread application of electrochemical water splitting, especially at industrial-level current densities. Herein, we report a novel heterostructural Ni-based metal organic framework (MOF)-Ni2P in-situ grown on iron foam (NiMOF-Ni2P/IF), which shows remarkable OER activity and stability. We demonstrate that the work function difference between NiMOF and Ni2P leads to the strong electron coupling effect by promoting electron transfer at the interface and results in a discernible upward shift of the d-band center of Ni sites for favorable OH− adsorption. The as-fabricated NiMOF-Ni2P/IF exhibits an ultralow overpotential of 330 mV and a small cell voltage of 1.796 V to drive NiMOF-Ni2P/IF‖Pt/C system at 1000 mA cm−2 in 1 M KOH, outperforming the majority of state-of-the-art non-noble-metal-based electrocatalysts. Furthermore, the catalyst shows remarkable performance even under harsh industrial conditions of 40, 60, and 80 °C in 6 M KOH. In addition, NiMOF-Ni2P/IF holds great promise with remarkable stability of 200 h and 600 cycles in simulated seawater and secondary zinc-air batteries (ZABs), respectively. This work offers a rational design strategy for low cost, high activity, and long durability OER electrocatalyst based on in-depth comprehension of the electronic coupling effect.

Research Progress and Future Expectations in Anode of Secondary Zinc-Air Batteries: A Review

Research Progress and Future Expectations in Anode of Secondary Zinc-Air Batteries: A Review

Benchmarking La‐Based Perovskites as Bifunctional Cathodes For Primary and Rechargeable Zinc−Air Batteries with Biopolymer‐Based Electrolyte

AbstractState‐of‐the‐art perovskite‐based electrocatalysts for zinc−air batteries (ZABs) may include one or more Critical Raw Materials (CRMs) like Co, Ru, and rare earth elements, for oxygen reduction/evolution reactions. Under the warnings described by the CRMs Act in Europe, future research in this field must limit the use of these elements, find more sustainable formulations, and better design/integration strategies to trade off costs, supply, and performances. In this benchmarking study, three main perovskites, i. e., LaNiO3‐δ (LNO), LaMnO3+δ (LMO), and LaMn0.5Ni0.5O3 (LMNO), are studied as quasi‐CRM‐free benchmarks and integrated with a novel gel electrolyte from a natural biopolymer in primary and secondary ZABs. By comparing literature performances based on the number of total/active site CRMs for the first time, these reference perovskites showed Zn utilizations >90 % in primary ZABs, with LMO and LMNO approaching 94 % at 2 mA/cm2, the highest result in the field. In secondary ZABs, LMO demonstrated limited cyclability (62 cycles), while LMNO had a moderate number of cycles (117 cycles) and the highest round‐trip efficiency (54.3 %), while LNO presented the lowest charge potential (2.04 V) and longer cyclability (455 cycles). This work demonstrates encouraging performance with fewer CRMs and proper integration in more sustainable ZABs, opening the way to future CRM‐free perovskites.

Polyelectrolyte complex membranes as a selective zincate separator for secondary zinc-air battery

Zinc-air batteries (ZABs) are being extensively studied as an alternative to lithium batteries due to their high energy density and overall safety benefit. While considerable attention has been given to the development of anodes and cathodes for ZABs, the separator membrane component has received relatively little focus. The separator is supposed to play a critical role in rechargeable ZABs by allowing hydroxide ions to permeate while blocking zincate ions. In this study, we investigated for the first time the potential use of polyelectrolyte complex (PEC) membranes as separators for rechargeable ZABs. These membranes were formed by mixing cationic poly(diallyldimethylammonium chloride) (PDADMAC) and anionic poly(sodium-4-styrenesulfonate) (PSS) at various molar ratios, followed by compression molding of the mixture precipitates after centrifugation. Among the different molar ratios tested, the non-stoichiometric PEC (2:1) membrane exhibited the highest ionic selectivity with a diffusion rate of 1.98 × 10−7 cm2 min−1 for Zn(OH)42−. Subsequently, the PEC membranes were integrated into homemade ZABs, and galvanostatic cycling tests were conducted. Overall, the PEC (2:1) membrane demonstrated superior separator ability for rechargeable ZABs compared to the other prepared molar ratios.

Effect of cell design on the durability of secondary zinc-air batteries

Secondary zinc-air batteries (ZAB) are promising sustainable energy storage systems, but their practical implementation has been hindered by a focus on materials, electrode/electrolyte design and formulations that do not translate into an efficient energy storage device. The prevailing cell design features an oversized zinc anode and an unbalanced electrolyte. As a result, the depth of discharge (DoD) of the zinc anode is typically low (<10%) and the durability of tests usually is limited to 500 h. This study focuses on evaluating the electrochemical impact of different cell designs for zinc-air batteries (ZABs) and highlights the critical role of positioning an electrolyte reservoir in close proximity to the zinc anode where a lifetime of up to 4000 h have been obtained. Our tests also involve high utilization of the zinc anode, ranging from 17.5% to 70.0% of the depth of discharge (DoD), equivalent to 136–546 mAh/gZn.

Agarose-based Gel Electrolytes for Sustainable Primary and Secondary Zinc-Air Batteries

Present Zn-air batteries (ZABs) are based on concentrated alkaline liquid electrolytes, with high ionic conductivity, but suffer from leakage, evaporation, and carbonate precipitation due to the semi-open characteristic of these systems. To overcome these issues, gel polymer electrolytes (GPEs), based on naturally occurring biopolymers, arise as a green option to overcome the above-mentioned limitations. In this work, a novel GPE based on pure agarose from seaweed is presented as a smart alternative to liquid (adsorbed on a separator) and gel electrolytes (based on synthetic polymers). The innovative synthesis method described can directly encapsulate concentrated KOH liquid electrolytes into an agarose matrix in one-pot; the process requiring approx. 10 min. The unique gel developed in this work, with 2 wt% agarose and 8 M KOH electrolyte, presents the best compromise between physicochemical and electrochemical properties, at lab scale. The characterization results revealed an outstanding ionic conductivity of 0.45 ± 0.05 S cm−1, ≈100% water retention up to 200–250 h, retarded Zn self-corrosion up to 30 days (symmetric cell under open circuit), average Zn utilization > 70–80% in primary ZABs in the range 1–20 mA cm−2 with peaks of ≈96%. In secondary ZABs the gel electrolyte presents high round-trip efficiency and improved cyclability at high areal capacities, under soft and severe cycling conditions, never tested before. This agarose gel represents a potential benchmark for future development of GPE-based ZABs for stationary applications.

High performance carbon free bifunctional air electrode for advanced zinc-air batteries

Secondary zinc-air batteries (ZABs) offer a promising alternative for the future of sustainable energy storage. However, the current capability of secondary ZABs is far from satisfactory. The limitations for achieving high reversibility are mainly related to the bifunctional air electrodes as it severely hampers practical applications and commercialization of secondary ZABs. Many efforts have been devoted to the development of efficient and corrosion resistant bifunctional electrocatalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In ZABs, carbon is commonly used as conductive additive, however, it has been observed that carbon materials are not resistant to the high positive voltages applied in electrical recharge. In this work, the use of metallic nickel as alternative conductive additive in bifunctional air electrodes is explored and compared with carbon nanotubes (CNT). We demonstrate that the chemical resistance of CNT does not limit the electrode performance; but the density of the additive as well as its interaction with the active material is crucial for achieving long cycle life. The use of Ni as conductive agent in secondary ZABs boosted the cycle life by delivering more than 2,400 cycles, in contrast to the 88 cycles delivered by the analogous carbon-based battery.

Secondary Zinc–Air Batteries: A View on Rechargeability Aspects

Metal–air batteries hold a competitive energy density and are frequently recommended as a solution for low-cost, environmentally friendly electrochemical energy storage applications. Rechargeable zinc–air batteries are prominently studied future devices for energy storage applications. Up to date and despite substantial efforts over the last decades, it is not commercialized on a broader scale because of inadequate performance. Most essential, the ultimate long-term functional zinc–air battery has yet to be discovered. This challenge should be resolved appropriately before articulating the zinc–air batteries to commercial reality and be deployed widespread. We review the present status and some breakthroughs in rechargeable zinc–air batteries research in the last few years, focusing on the anode-related issues. A critical overview of the last five years of the still less explored but essential aspects of rechargeability in zinc–air batteries, such as zinc utilization, solid electrolyte interface, and cell design is presented, some perspectives on possible solutions are offered.

N, S co-doped carbon with embedment of FeNi alloy as bifunctional oxygen electrocatalysts for rechargeable Zinc-air batteries

Zinc-air batteries (ZABs) have sparked great interest, but their wide-ranging applications are limited by sluggish cathode reactions (ORR and OER). In this work, a multifunctional 3D catalyst (FeNi alloy/porous carbon) was easily fabricated by introducing Fe3+ and Ni2+ to modulate in-situ vapor phase grown carbon nanotubes. The as-prepared catalyst FNSNC73-800 displays abundant mesoporous, massive structural defects, and multiple active sites, which greatly facilitate the transport of oxygen species and charge transfer during the reaction. Due to the excellent ORR and OER performance, FNSNC73-800 shows a narrow voltage gap (ΔE) of 0.76 V, which is superior to recent reports. Notably, the secondary zinc-air battery with this catalyst displays a high-peak power density (210 mW cm−2), while maintaining an ultra-low potential gap (0.74 V) after a long-term charge-discharge cycle of 200 h. This effort presents a facile strategy for designing economical and efficient 3D catalysts for zinc-air batteries and more energy devices.

Synergistic Effect of Co9S8 and FeS2 Inlaid on N-Doped Carbon Nanofibers toward a Bifunctional Catalyst for Zn-Air Batteries.

The development of economical and energy-efficient electrocatalysts is essential for the wide-scale application of secondary zinc-air batteries (ZABs). Herein, we prepared Co9S8 and FeS2 nanoparticles inlaid on N-doped carbon nanofibers (Co9S8-FeS2@N-CNFs), which were derived from the in situ growth of Fe-doped ZIF-67 nanosheet arrays on electrospun nanofibers and a subsequent sulfidation process. The Co9S8-FeS2@N-CNFs display excellent electrocatalytic performances for OER (Ej=10, 330 mV) and ORR (E1/2, 0.80 V) as well as a smaller charge and discharge gap (ΔE, 0.76 V) in KOH electrolyte, allowing it to be employed as an attractive air cathode bifunctional catalyst for secondary ZABs. The electrocatalytic performance of the composite materials (Co9S8-FeS2@N-CNFs) is obviously better than that of the single-component materials (FeS2@N-CNFs and Co9S8@N-CNFs). The improved catalytic performance is mainly attributed to the synergistic effect of the two transition-metal sulfides and the optimization of the structure. Furthermore, the peak power density of the assembled aqueous/solid-state ZABs based on Co9S8-FeS2@N-CNFs can reach 214 and 91 mW cm-2 with excellent stability, respectively, which outperforms the ones based on commercial precious-metal-based catalysts. We anticipate that our work will provide new inspiration for the design of MOF-derived sulfides as multifunctional catalysts.

A self-supported bifunctional air cathode composed of Co3O4/Fe2O3 nanoparticles embedded in nanosheet arrays grafted onto carbon nanofibers for secondary zinc-air batteries

Secondary zinc-air batteries (ZABs) with a free-standing and flexible air electrode integrated with distinguished bifunctional oxygen electrocatalysts are crucial for achieving better performance. Herein, benefitting from the rational design and simple synthesis, a highly controlled design can be achieved for the first showing of the synthesis of Co3O4/Fe2O3NAs@CNFs with a unique hierarchical nanostructure, consisting of randomly distributed zero-dimensional (0D) Co3O4/Fe2O3 nanoparticles embedded in two-dimensional (2D) MOF derived nitrogen-doped mesoporous carbon flake nanoarrays grown on three-dimensional (3D) microporous network with interconnected conductive one-dimensional (1D) carbon nanofibers from carbonized electrospinning polymer nanofiber film (PMNFs). Under the synergy of 3D hierarchical porous nanostructure and abundant accessible active sites, Co3O4/Fe2O3NAs@CNFs is endowed with excellent bifunctional electrocatalytic activities like those of commercial Pt/C and RuO2, respectively. Rechargeable aqueous ZABs based on Co3O4/Fe2O3NAs@CNFs as air electrodes outperform their counterparts based on Pt/C and RuO2 loaded carbon nanofibers (CNFs) as air electrodes, with a maximum power density of 246 mW cm−2 and excellent cycling stability with no increased polarization even after 40 h. And the assembled flexible solid-state ZABs with Co3O4/Fe2O3NAs@CNFs also display superior performance and bendability.

Three-dimensional ordered structure for highly reversible neutral zinc-air battery

In view of the low utilization rate of zinc in secondary zinc-air batteries, 3DOM (three-dimensionally ordered macroporous) Ni was constructed on the steel mesh by colloidal crystal template-electrodeposition method, which significantly improved the interface area and optimized the electric field distribution in the electrodeposition process. Meanwhile, the ZIF-8 derivative is uniformly coated on the surface of 3DOM nickel to inhibit the hydrogen evolution reaction in the electrodeposition process of zinc, improving the affinity of electrode surface to zinc, and realizing the uniform electrodeposition of zinc. Finally, a highly reversible negative electrode material for neutral zinc-air battery was obtained, and 200 cycles were realized at a depth of discharge (DOD) of 41.7%.

Potassium Cobalt Pyrophosphate as a Nonprecious Bifunctional Electrocatalyst for Zinc-Air Batteries.

Economic and sustainable (ecological) energy storage forms a major pillar of the global energy sector. Bifunctional electrocatalysts, based on oxygen electrolysis, play a key role in the development of rechargeable metal-air batteries. Pursuing precious metal-free economic catalysts, here, we report K2CoP2O7 pyrophosphate as a robust cathode for secondary zinc-air batteries with efficient oxygen evolution and oxygen reduction (OER||ORR) activity. Prepared by autocombustion, nanoscale K2CoP2O7 exhibited excellent oxygen reduction and evolution reactions among all phosphate-based electrocatalysts. In particular, the OER activity surpassed that of commercial RuO2 with low overpotential (0.27 V). First-principles calculations revealed that the bifunctional activity is rooted in the Co active site with the CoO5 local coordination in the most stable (110) surface. This nanostructured (tetragonal) pyrophosphate can be harnessed as an economic bifunctional catalyst for zinc-air batteries.

Biomass-derived cobalt/carbon hierarchically structured composites for efficient oxygen electrocatalysis and zinc–air batteries

In this work, we constructed a biomass-derived composite (denoted as Co@Co–N,S–C), which exhibited excellent efficient bifunctional performance for ORR/OER, as well as an outstanding performance when employed in secondary zinc–air batteries.

Essential data for industrially relevant development of bifunctional cathodes and biopolymer electrolytes in solid-state zinc–air secondary batteries

The development of bio-based gel polymer electrolytes and bifunctional cathodes with no/less CRM-based catalysts is urgently required for ZABs to push sustainability for full cell design and validation by adopting correct protocols and metrics.

Solvation and Ion-Pairing Effects of Choline Acetate Electrolyte in Protic and Aprotic Solvents Studied by NMR Titrations.

Choline‐based electrolytes have been proposed as environmentally friendly and low‐cost alternatives for secondary zinc air batteries. Choline acetate [Ch]+[OAc]− in protic (D2O) and aprotic (DMSO‐d6) solvents has been studied by means of concentration‐dependent 1H NMR, viscosity, and density measurements. The viscosities have been calculated on the basis of the Jones‐Dole equation and showed that the dominant contribution originates from short‐range ion‐solvent interactions. Site‐specific association affinities were assigned from NMR chemical shift titrations. In DMSO‐d6, the hydroxyl group of choline was found to have the smallest dissociation constant followed by the methyl group of acetate. The corresponding Gibbs energies at low concentration were found to be in agreement with a solvent‐separated ion pair (2SIP) configuration, whereas at concentrations above 300 mM, a solvent‐shared ion pair (SIP) configuration was assigned. For [Ch]+[OAc]− in D2O, association effects were found to be weaker, attributed to the high dielectric constant of the solvent. On time scales on the order of 100 ms, NMR linewidth perturbations indicated a change in the local rotational dynamics of the ions, attributed to short‐range cation‐solvent interactions and not to solvent viscosity. At 184 mM, ∼ 40 % of the cations in DMSO‐d6 and ∼ 10 % in D2O were found to exhibit short‐range interactions, as indicated by the linewidth perturbations. It was found that at about 300 mM, the ions in DMSO‐d6 exhibit a transition from free to collective translational dynamics on time scales on the order of 400 ms. In DMSO‐d6, both ions were found to be almost equally solvated, whereas in D2O solvation of acetate was stronger, as indicated by the obtained effective hydrodynamic radii. For [Ch]+[OAc]− in DMSO‐d6, the results suggest a solvent‐shared ion association with weak H‐bonding interactions for concentrations between 0.3–1 M. Overall, the extent of ion association in solvents such as DMSO is not expected to significantly limit charge transport and hinder the performance of choline‐based electrolytes.

Advanced Oxygen Electrocatalyst for Air-Breathing Electrode in Zn-Air Batteries.

The electrochemical reduction of oxygen to water and the evolution of oxygen from water are two important electrode reactions extensively studied for the development of electrochemical energy conversion and storage technologies based on oxygen electrocatalysis. The development of an inexpensive, highly active, and durable nonprecious-metal-based oxygen electrocatalyst is indispensable for emerging energy technologies, including anion exchange membrane fuel cells, metal-air batteries (MABs), water electrolyzers, etc. The activity of an oxygen electrocatalyst largely decides the overall energy storage performance of these devices. Although the catalytic activities of Pt and Ru/Ir-based catalysts toward an oxygen reduction reaction (ORR) and an oxygen evolution reaction (OER) are known, the high cost and lack of durability limit their extensive use for practical applications. This review article highlights the oxygen electrocatalytic activity of the emerging non-Pt and non-Ru/Ir oxygen electrocatalysts including transition-metal-based random alloys, intermetallics, metal-coordinated nitrogen-doped carbon (M-N-C), and transition metal phosphides, nitrides, etc., for the development of an air-breathing electrode for aqueous primary and secondary zinc-air batteries (ZABs). Rational surface and chemical engineering of these electrocatalysts is required to achieve the desired oxygen electrocatalytic activity. The surface engineering increases the number of active sites, whereas the chemical engineering enhances the intrinsic activity of the catalyst. The encapsulation or integration of the active catalyst with undoped or heteroatom-doped carbon nanostructures affords an enhanced durability to the active catalyst. In many cases, the synergistic effect between the heteroatom-doped carbon matrix and the active catalyst plays an important role in controlling the catalytic activity. The ORR activity of these catalysts is evaluated in terms of onset potential, number of electrons transferred, limiting current density, and durability. The bifunctional oxygen electrocatalytic activity and ZAB performance, on the other hand, are measured in terms of potential gap between the ORR and OER, ΔE = Ej10OER - E1/2ORR, specific capacity, peak power density, open circuit voltage, voltaic efficiency, and charge-discharge cycling stability. The nonprecious metal electrocatalyst-based ZABs are very promising and they deliver high power density, specific capacity, and round-trip efficiency. The active site for oxygen electrocatalysis and challenges associated with carbon support is briefly addressed. Despite the considerable progress made with the emerging electrocatalysts in recent years, several issues are yet to be addressed to achieve the commercial potential of rechargeable ZAB for practical applications.

Projecting the Specific Energy of Rechargeable Zinc–Air Batteries

Commercial primary zinc–air batteries provide 450 Wh kgcell–1 (at the cell level), but the practical specific energy of secondary zinc–air batteries remains unclear. Using a specific-energy model a...

New Insights of Zn2+/Li+ Hybrid Aqueous Batteries

The integration of energy storage systems into intermittent renewable energy sources in power grids ensures the continuity of the energy supply in a balanced and efficient way. Novel rechargeable zinc ion and zinc hybrid aqueous technologies constitute paradigmatic examples of promising alternative energy storage systems for large‐scale applications, due to their intrinsic low cost, environmental friendliness, safety, high power density, and ease of operation. This work evaluates the performance improvement of zinc/LiFePO4 and zinc/LiMn2O4 batteries through the incorporation of an alternative chloride‐based electrolyte formulation inspired in Leclanché battery technology and also, in recently reported secondary zinc–air batteries. The use of this alternative electrolyte shows an increased working voltage and improves capacity retention for both zinc/LiFePO4 and zinc/LiMn2O4 batteries. This work analyses for the first time the specific energy of zinc‐based hybrid aqueous batteries in a functional cell, by means of the incorporation of light zinc anode and Li+‐based cathode which comprises superior active material loading. This approach demonstrates the feasibility of reversible zinc‐based hybrid aqueous batteries with more than 90 W h kg−1Active materials as to 13 W h kg−1Active materials of the baseline technology.

Enhancing bifunctional catalytic activity of cobalt-nickel sulfide spinel nanocatalysts through transition metal doping and its application in secondary zinc-air batteries.

Developing large-scale and high-performance OER (oxygen evolution reaction) and ORR (oxygen reduction reaction) catalysts have been a challenge for commercializing secondary zinc–air batteries. In this work, transition metal-doped cobalt–nickel sulfide spinels are directly produced via a continuous hydrothermal flow synthesis (CHFS) approach. The nanosized cobalt–nickel sulfides are doped with Ag, Fe, Mn, Cr, V, and Ti and evaluated as bifunctional OER and ORR catalyst for Zn–air battery application. Among the doped spinel catalysts, Mn-doped cobalt–nickel sulfides (Ni1.29Co1.49Mn0.22S4) exhibit the most promising OER and ORR performance, showing an ORR onset potential of 0.9 V vs. RHE and an OER overpotential of 348 mV measured at 10 mA cm−2, which is attributed to their high surface area, electronic structure of the dopant species, and the synergistic coupling of the dopant species with the active host cations. The dopant ions primarily alter the host cation composition, with the Mn(iii) cation linked to the introduction of active sites by its favourable electronic structure. A power density of 75 mW cm−2 is achieved at a current density of 140 mA cm−2 for the zinc–air battery using the manganese-doped catalyst, a 12% improvement over the undoped cobalt–nickel sulfide and superior to that of the battery with a commercial RuO2 catalyst.