Recent advances in zinc-air batteries

N-, Fe-Doped carbon sphere/oriented carbon nanofiber nanocomposite with synergistically enhanced electrochemical activities

Excellent electrocatalyst for oxygen reduction in zinc–air batteries: N-, Fe-doped carbon sphere/oriented carbon nanofiber nanocomposite was prepared. The typical product is a competitive alternative to commercial Pt/C in the practical application of zinc–air batteries.

The design of Fe, N-doped hierarchically porous carbons as highly active and durable electrocatalysts for a Zn–air battery

A new type of Fe, N-doped hierarchically porous carbons (N–Fe-HPCs) has been synthesized via a green and simple silicate templated two-step graphitization of N-enriched polyquaternium networks.

Selective nitrogen bonding states in nitrogen-doped carbon via a solution plasma process for advanced oxygen reduction reaction

Selective nitrogen bonding within nitrogen-doped carbon nanoparticles was achieved by altering linear and heterocyclic precursor via solution plasma.

Shrimp-shell derived carbon nanodots as precursors to fabricate Fe,N-doped porous graphitic carbon electrocatalysts for efficient oxygen reduction in zinc–air batteries

Shrimp-shell derived N-doped carbon nanodots as precursors are used to fabricate Fe, N-doped porous carbon electrocatalysts exhibiting superior ORR activity in zinc–air batteries.

Functionalized carbon nanotubes and graphene-based materials for energy storage

This feature article summarizes recent progress in the functionalization of carbon nanotubes and graphene for energy storage applications in supercapacitors and batteries.

Cobalt nanoparticles encapsulated in N-doped graphene nanoshells as an efficient cathode electrocatalyst for a mechanical rechargeable zinc–air battery

Air-cathodes with properties of efficiency, durability and low cost are essential for high performance metal–air batteries and fuel cells for practical applications.

Metal coordination enhanced Ni–Co@N-doped porous carbon core–shell microsphere bi-functional electrocatalyst and its application in rechargeable zinc/air batteries

Primary and rechargeable zinc/air batteries could be the next generation of energy storage devices because of their high power density and safety.

Spherical nitrogen-doped hollow mesoporous carbon as an efficient bifunctional electrocatalyst for Zn-air batteries

Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO(2) template that is removed upon hydrofluoric acid etching. The morphology and structural features of these HMCs were evaluated using scanning electron microscopy and transmission electron microscopy and the N-doping (7.1 at%) was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen reduction/evolution reaction (ORR/OER) performance of N-doped HMC was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte. N-doped HMC demonstrated a high ORR onset potential of -0.055 V (vs. Hg/HgO) and excellent stability. The outstanding bifunctional activity was implemented in a practical Zn-air battery (ZAB), which exhibited a small charge-discharge voltage polarization of 0.89 V and high stability over repeated cycling.

Lithium Sulfur Primary Battery with Super High Energy Density: Based on the Cauliflower-like Structured C/S Cathode

The lithium-sulfur primary batteries, as seldom reported in the previous literatures, were developed in this work. In order to maximize its practical energy density, a novel cauliflower-like hierarchical porous C/S cathode was designed, for facilitating the lithium-ions transport and sulfur accommodation. This kind of cathode could release about 1300 mAh g⁻¹ (S) capacity at sulfur loading of 6 ~ 14 mg cm⁻², and showed excellent shelf stability during a month test at room temperature. As a result, the assembled Li-S soft package battery achieved an energy density of 504 Wh kg⁻¹ (654 Wh L⁻¹), which was the highest value ever reported to the best of our knowledge. This work might arouse the interests on developing primary Li-S batteries, with great potential for practical application.

Flexible High-Energy Polymer-Electrolyte-Based Rechargeable Zinc-Air Batteries

A thin-film, flexible, and rechargeable zinc-air battery having high energy density is reported particularly for emerging portable and wearable electronic applications. This freeform battery design is the first demonstrated by sandwiching a porous-gelled polymer electrolyte with a freestanding zinc film and a bifunctional catalytic electrode film. The flexibility of both the electrode films and polymer electrolyte membrane gives great freedom in tailoring the battery geometry and performance.

Highly Active and Durable Nanocrystal-Decorated Bifunctional Electrocatalyst for Rechargeable Zinc-Air Batteries

A highly active and durable bifunctional electrocatalyst that consists of cobalt oxide nanocrystals (Co3 O4 NC) decorated on the surface of N-doped carbon nanotubes (N-CNT) is introduced as effective electrode material for electrically rechargeable zinc-air batteries. This active hybrid catalyst is synthesized by a facile surfactant-assisted method to produce Co3 O4 NC that are then decorated on the surface of N-CNT through hydrophobic attraction. Confirmed by half-cell testing, Co3 O4 NC/N-CNT demonstrates superior oxygen reduction and oxygen evolution catalytic activities and has a superior electrochemical stability compared to Pt/C and Ir/C. Furthermore, rechargeable zinc-air battery testing of Co3 O4 NC/N-CNT reveals superior galvanodynamic charge and discharge voltages with a significantly extended cycle life of over 100 h, which suggests its potential as a replacement for precious-metal-based catalysts for electric vehicles and grid energy storage applications.

Development of Cobalt Hydroxide as a Bifunctional Catalyst for Oxygen Electrocatalysis in Alkaline Solution

Co(OH)2 in the form of hexagonal nanoplates synthesized by a simple hydrothermal reaction has shown even greater activity than cobalt oxides (CoO and Co3O4) in oxygen reduction and oxygen evolution reactions (ORR and OER) under alkaline conditions. The bifunctionality for oxygen electrocatalysis as shown by the OER-ORR potential difference (ΔE) could be reduced to as low as 0.87 V, comparable to the state-of-the-art non-noble bifunctional catalysts, when the Co(OH)2 nanoplates were compounded with nitrogen-doped reduced graphene oxide (N-rGO). The good performance was attributed to the nanosizing of Co(OH)2 and the synergistic interaction between Co(OH)2 and N-rGO. A zinc-air cell assembled with a Co(OH)2-air electrode also showed a performance comparable to that of the state-of-the-art zinc-air cells. The combination of bifunctional activity and operational stability establishes Co(OH)2 as an effective low-cost alternative to the platinum group metal catalysts.

Mn-Co oxide/PEDOT as a bifunctional electrocatalyst for oxygen evolution/reduction reactions

Bifunctional electrocatalysts, which facilitate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), are vital components in advanced metal-air batteries. Results are presented for carbon-free, nanocrystalline, rod-like, Mn-Co oxide/PEDOT bifunctional electrocatalysts, prepared by template-free sequential anodic electrodeposition. Electrochemical characterization of synthesized electrocatalysts, with and without a conducting polymer (PEDOT) coating, was performed using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). In addition, microstructural characterization was conducted using SEM, TEM, STEM and XPS. Mn-Co oxide/PEDOT showed improved ORR/OER performance relative to Mn-Co oxide and PEDOT. On the basis of rotating disk electrode (RDE) experiments, Mn-Co oxide/PEDOT displayed the desired 4-electron transfer oxygen reduction pathway. Comparable ORR activity and superior OER activity relative to commercial Pt/C were observed.

Ag-Cu nanoalloyed film as a high-performance cathode electrocatalytic material for zinc-air battery

A novel Ag50Cu50 film electrocatalyst for oxygen reduction reaction (ORR) was prepared by pulsed laser deposition (PLD) method. The electrocatalyst actually is Ag-Cu alloyed nanoparticles embedded in amorphous Cu film, based on transmission electron microscopy (TEM) characterization. The rotating disk electrode (RDE) measurements provide evidence that the ORR proceed via a four-electron pathway on the electrocatalysts in alkaline solution. And it is much more efficient than pure Ag catalyst. The catalytic layer has maximum power density of 67 mW cm(-2) and an acceptable cell voltage at 0.863 V when current densities increased up to 100 mA cm(-2) in the Ag50Cu50-based primary zinc-air battery. The resulting rechargeable zinc-air battery exhibits low charge-discharge voltage polarization of 1.1 V at 20 mAcm(-2) and high durability over 100 cycles in natural air.

Co3O4 nanoparticles decorated carbon nanofiber mat as binder-free air-cathode for high performance rechargeable zinc-air batteries

An efficient, durable and low cost air-cathode is essential for a high performance metal-air battery for practical applications. Herein, we report a composite bifunctional catalyst, Co3O4 nanoparticles-decorated carbon nanofibers (CNFs), working as an efficient air-cathode in high performance rechargeable Zn-air batteries (ZnABs). The particles-on-fibers nanohybrid materials were derived from electrospun metal-ion containing polymer fibers followed by thermal carbonization and a post annealing process in air at a moderate temperature. Electrochemical studies suggest that the nanohybrid material effectively catalyzes oxygen reduction reaction via an ideal 4-electron transfer process and outperforms Pt/C in catalyzing oxygen evolution reactions. Accordingly, the prototype ZnABs exhibit a low discharge-charge voltage gap (e.g. 0.7 V, discharge-charge at 2 mA cm(-2)) with higher stability and longer cycle life compared to their counterparts constructed using Pt/C in air-cathode. Importantly, the hybrid nanofiber mat readily serves as an integrated air-cathode without the need of any further modification. Benefitting from its efficient catalytic activities and structural advantages, particularly the 3D architecture of highly conductive CNFs and the high loading density of strongly attached Co3O4 NPs on their surfaces, the resultant ZnABs show significantly improved performance with respect to the rate capability, cycling stability and current density, promising good potential in practical applications.

One-dimensional manganese-cobalt oxide nanofibres as bi-functional cathode catalysts for rechargeable metal-air batteries

Rechargeable metal-air batteries are considered a promising energy storage solution owing to their high theoretical energy density. The major obstacles to realising this technology include the slow kinetics of oxygen reduction and evolution on the cathode (air electrode) upon battery discharging and charging, respectively. Here, we report non-precious metal oxide catalysts based on spinel-type manganese-cobalt oxide nanofibres fabricated by an electrospinning technique. The spinel oxide nanofibres exhibit high catalytic activity towards both oxygen reduction and evolution in an alkaline electrolyte. When incorporated as cathode catalysts in Zn-air batteries, the fibrous spinel oxides considerably reduce the discharge-charge voltage gaps (improve the round-trip efficiency) in comparison to the catalyst-free cathode. Moreover, the nanofibre catalysts remain stable over the course of repeated discharge-charge cycling; however, carbon corrosion in the catalyst/carbon composite cathode degrades the cycling performance of the batteries.

Eggplant-derived microporous carbon sheets: towards mass production of efficient bifunctional oxygen electrocatalysts at low cost for rechargeable Zn–air batteries

Microporous carbon sheets derived from eggplant via carbonization and KOH activation serve as efficient bifunctional catalysts for high performance zinc–air batteries.

Hierarchical nanoarray materials for advanced nickel–zinc batteries

Due to the unique structural advantages, hierarchical Co₃O₄@NiO nanoarrays can be regarded as advanced electrodes for Ni–Zn batteries.

Zinc bromide in aqueous solutions of ionic liquid bromide salts: the interplay between complexation and electrochemistry

Voltammetric studies of ZnBr₂ (50 mM) in aqueous equimolar solutions of ionic liquid bromide salts (1-alkyl-1-methylpyrrolidinium bromide, [C_nMPyrr], and tetraalkylammonium bromide, [N_n,n,n,n]Br, 50 mM, where n = 2, 4 or 6) are reported.

Structural design of graphene for use in electrochemical energy storage devices

This review elucidates the structural design methodologies toward high-performance graphene-based electrode materials for electrochemical energy storage devices.

Co3O4 nanoparticles grown on N-doped Vulcan carbon as a scalable bifunctional electrocatalyst for rechargeable zinc–air batteries

Balancing the loading of in situ grown Co₃O₄ nanoparticles with the N-doped Vulcan carbon underneath is essential to produce scalable high-performance bifunctional catalysts of Co₃O₄/NVC for rechargeable Zn–air batteries.

A one-pot method to prepare a ZnO/Ag/polypyrrole composite for zinc alkaline secondary batteries

A ZnO/Ag/polypyrrole (ZAP) composite was synthesized by a facile one-pot method in which silver ammonia complex ions were reduced to metallic silver using a pyrrole monomer as the reducing agent. Meanwhile, the pyrrole monomer was oxidized and formed polypyrrole.

Porous nanoarchitectures of spinel-type transition metal oxides for electrochemical energy storage systems

Transition metal oxides possessing two kinds of metals (denoted as A_xB_3−xO₄, which is generally defined as a spinel structure; A, B = Co, Ni, Zn, Mn, Fe,etc.), with stoichiometric or even non-stoichiometric compositions, have recently attracted great interest in electrochemical energy storage systems (ESSs).

Electrode Nanostructures in Lithium-Based Batteries

Lithium-based batteries possessing energy densities much higher than those of the conventional batteries belong to the most promising class of future energy devices. However, there are some fundamental issues related to their electrodes which are big roadblocks in their applications to electric vehicles (EVs). Nanochemistry has advantageous roles to overcome these problems by defining new nanostructures of electrode materials. This review article will highlight the challenges associated with these chemistries both to bring high performance and longevity upon considering the working principles of the various types of lithium-based (Li-ion, Li-air and Li-S) batteries. Further, the review discusses the advantages and challenges of nanomaterials in nanostructured electrodes of lithium-based batteries, concerns with lithium metal anode and the recent advancement in electrode nanostructures.

Retaining the 3D framework of zinc sponge anodes upon deep discharge in Zn-air cells

We fabricate three-dimensional zinc electrodes from emulsion-cast sponges of Zn powder that are thermally treated to produce rugged monoliths. This highly conductive, 3D-wired aperiodic scaffold achieves 740 mA h gZn(-1) when discharged in primary Zn-air cells (>90% of theoretical Zn capacity). We use scanning electron microscopy and X-ray diffraction to monitor the microstructural evolution of a series of Zn sponges when oxidized in Zn-air cells to specific depths-of-discharge (20, 40, 60, 80% DOD) at a technologically relevant rate (C/40; 4-6 mA cm(-2)). The Zn sponges maintain their 3D-monolithic form factor at all DOD. The cell resistance remains low under all test conditions, indicating that an inner core of metallic Zn persists that 3D-electrically wires the electrode, even to deep DOD.