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• The bifunctional electrocatalyst, Ni(OH) 2 -CNT-Co 3 O 4 /NC, with good ORR and OER performance was prepared by thermal processes of ZIF-67@ZIF-8 and CBD. • The synergistic effect of the Ni(OH) 2 , Co 3 O 4 , N-doping in the catalyst showed high activities compared to the Pt/C and Ir/C catalyst. • The porous and graphitized carbon framework and CNTs in the catalyst are important for the electron conductivity and ion diffusion. • The Zn-air battery with the electrocatalyst demonstrated a high specific capacity of 805.4 mAh g−1 and energy density of 1021.7 Wh Kg−1. • The charge-discharge tests showed a very stable potential gap (0.65 V) with an excellent retention of 94.5% after 4500 cycles at 10 mA cm−2. A rechargeable zinc-air battery (RZAB) is a hopeful alternative battery solution to meet the world's ever-increasing energy storage need. Developing a high-performance electrocatalyst is one of the most critical challenges that need to be addressed for the RZAB to fulfill that role. A Ni(OH) 2 -CNT-Co 3 O 4 /NC catalyst consisting of carbon nanotube (CNT), cobalt oxide, and nitrogen-doped functionalities embedded in a porous carbon framework with two-dimensional Ni(OH) 2 nanosheets is reported. The prepared catalytic material, Ni(OH) 2 -CNT-Co 3 O 4 /NC, showed a high limit current density of -6.409 mA cm−2 during the oxygen reduction reaction (ORR), surpassing that of the commercial Pt/C (-5.625 mA cm−2). The oxygen evolution reaction (OER) potential for this electrocatalyst also reached 1.653 V at a current density of 10 mA cm−2, which is close to that of the commercial RuO 2 and thus showed excellent catalytic activity for the OER. As a bifunctional catalyst in the RZAB, the Ni(OH) 2 -CNT-Co 3 O 4 /NC electrocatalyst exhibited a high power density of 244.5 mW cm−2, and cycled 4500 times at a current density of 10 mA cm−2 while displaying good charge and discharge stability. Based upon these performances, we believe that the Ni(OH) 2 -CNT-Co 3 O 4 /NC catalyst can serve as an excellent bifunctional catalyst in the next-generation RZAB. [Display omitted] [ABSTRACT FROM AUTHOR]

The inhibitive effects of functional groups originating from the presence of additives on corrosion are linked to the physicochemical and electronic properties of these surficial chemical species. In this work, the acetoxy group (i.e. weak bases) with different orbital characters is integrated with donating/accepting molecules which reveals dissimilar inhibitive behaviour. Introducing cations on the acetoxy groups (-Ac) as additives leads to mitigation of undesirable self-corrosion of the anode. The Al-air battery corresponded to a maximum capacity of 2817 mAhg−1 at 10 mAcm−2 with the use of barium-Ac/KOH electrolyte, demonstrates nearly 95% of the theoretical capacity. However, a capacity of only 2392 mAhg−1 is observed for free additive. In addition, the maximum power density (i.e. 91.32 mWcm−2) increased by nearly 50% with the employment of barium-Ac/KOH. The rechargeable Al–air battery based on barium-Ac/KOH presents a low voltage gap of 0.83 V with a remarkable cyclic stability of 25,000 s. The results show that the acetoxy group integrated with metal ions can be a key player in reducing H 2 evolution rate in the aluminium-air batteries. XPS analysis confirmed an Al-complex (i.e. Al-acetoxy) is formed using barium-ac. DFT calculations confirmed that barium-Ac/KOH provides the minimum value of ΔE (about 5.4 eV), indicating the remarkable ability for reacting with Al+3 ions to adsorb on the anode surface leading to complex (Ba-Ac-Al3+) formation. This study highlights the parasitic corrosion reaction leading to low coulombic efficiency in rechargeable Al- air batteries. • The impacts of additive integrated with acetoxy group was studied on Al corrosion and H2 evolution. • The corrosion inhibition efficiency follows the order of: Ba-acetoxy > Ca-acetoxy > Ethyl-acetoxy. • Ba–Ac/KOH exhibited the optimum discharge capacity 2817 mAh/g and 95% Al utilization. • XPS results revealed a complex containing Al-acetoxy contribute to reduce Al self-corrosion. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Fe-Ni-Zn triple single atom catalyst is an excellent bifunctional catalyst for ORR and OER. • XAS and TEM studies confirm Fe, Ni and Zn SAC atomically dispersed in the matrix. • The SAC(Fe,Ni,Zn) with an optimal Fe/Ni ratio of 5:5 is used for ZAB. • The battery has good specific capacity(809 mAh/g @ 50 mA cm−2) and excellent power density of 300 mW cm−2 @ 406 mA cm−2. • A rechargeable Zn-air battery has superior cycle stability with 2150 cycles (358.3 h). The rechargeable Zn-air battery (ZAB) is a promising device for energy storage. A good bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a decisive role in the ZAB. Here, we prepare a Fe-Ni-Zn triple single-atom catalyst (SAC) anchored in the nitrogen-doped porous carbon framework (NC) denoted as SAC(Fe, Ni, Zn)/NC or A-SAC(Fe, Ni, Zn)/NC (ammonia-treated) for the ZAB study. We found that not only Fe-N x , Ni-N x , and Zn-N x act as excellent catalytic sites for ORR and OER, but the synergetic effect by the three adjacent SAC(Fe, Ni, Zn) in the NC enhances the catalytic performance. As a result, the voltage difference (ΔE) of 0.75 V is achieved (half-wave potential of ORR: 0.88 V and the potential of OER at 10 mA cm−2: 1.63 V). In the rechargeable ZAB study, the battery with the A-SAC(Fe, Ni, Zn)/NC has a good specific capacity of 809 mAh/g @ 50 mA cm−2, the excellent power density of 300 mW cm−2 @ 406 mA cm−2 and superior cycle stability (2150 cycles, 358.3 h @ 10 mA cm−2) while the all-soild-state ZAB showed promising power density of 64.5 mW cm−2 and acceptable cycling durability over 25 h@1 mA cm−2. Triple SAC(Fe, Ni, Zn) in the hierarchical porous NC possesses the bifunctional catalytic capability, high ionic diffusivity, and electron conductivity. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable Zn-ion batteries (ARZIB) are promising candidates for next-generation batteries because of their high safety, low cost, and relatively high capacity. In this study, we developed hydrated and potassium-doped manganese dioxide (MO) nanowires mixed with carbon nanotubes (CNT) on a graphene substrate (hydrated KMO-CNT/graphene) for ARZIB. A simple polyol process using poly(ethyl glycol), KMnO 4 , CNT, and graphene was utilized to fabricate hydrated KMO-CNT/graphene. MnO 2 nanowires with diameters of 15–25 nm possess a high specific capacity with a short diffusion path. The intercalated K ions and hydrates in the layered MnO 2 nanowires maintained the MO structure during the charge and discharge processes, whereas carbon nanomaterials (CNT and graphene) enhanced the conductivity of the material. Consequently, hydrated KMO-CNT/graphene demonstrated good ARZIB performance. A high capacity of 359.8 mAh g–1 at 0.1 A g–1, and at a high current density of 3.0 A g–1, a capacity of 129 mAh g–1 with 77% retention after 1000 cycles, were achieved. • Hydrated and potassium-doped MnO 2 mixed with CNT on graphene substrate is synthesized. • Polyol process was conducted with PEG, KMnO 4 , CNT and graphene. • MnO 2 has a high capacity, intercalated K and H 2 O keep the structure of MnO 2 and CNT/graphene provide conductivity. • The hydrated KMO-CNT/graphene delivers high specific capacities of 359.8 mAh g–1 at 0.1 A g–1 and 129 mAh g–1 at 3.0 A g–1 with 77% retention. • The performance of ZIB reaches a high energy density of 410.36 Wh kg–1 at 109.93 W kg–1. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel CNT-CoFe/NC and CNT-CoS 2 Fe/NC was fabricated by thermal treatments and vulcanization. • CNT-CoFe/NC shows a better ORR performance than Pt/C while CNT-CoS 2 Fe/NC shows a better OER performance than RuO 2. • The hybrid catalysts, CNT-CoFe/NC + CNT-CoS 2 Fe/NC, demonstrate a superior performance of rechargeable Zn-air battery. Catalysts with embedded and functionalized elements used for the effective control of oxygen-reduction (ORRs) and oxygen-evolution reactions (OERs) are the key to developing high-performance rechargeable Zn–air batteries (ZABs). Here, carbon nanotube-grafted, Co–Fe embedded, nitrogen-doped porous carbon nano-frameworks (CNT–Co–Fe/NC) were synthesized through the carbonization of Fe-doped zeolitic imidazolate frameworks and vulcanization of the CNT–Co–Fe/NC to form CNT–CoS 2 –Fe/NC. The CNT–CoS 2 –Fe/NC exhibited a superior OER performance with an overpotential of only 1.637 mV at a current density of 10 mA/cm2 and a Tafel slope of 197 mV/dec (which, for RuO 2 , is 112 mV/dec), whereas the CNT–Co–Fe/NC showed an excellent ORR performance with a Tafel slope of 71 mV/dec (which, for 20 wt% Pt/C, is 91 mV/dec). A ZAB was developed with a hybrid catalyst of 50 wt% CNT–Co–Fe/NC and 50 wt% CNT–CoS 2 –Fe/NC in the cathode, and it achieved an excellent specific discharge capacity of 814 mAh/g at 50 mA/cm2, high power density of 245 mW/cm2, and outstanding cycle stability of over 1800 cycles (300 h) at 10 mA/cm2 with a very high retention of 95% and small potential gap of 0.68 V, compared to the corresponding values of 803.7 mAh/g, 215.3 mW/cm2, 900 cycles: retention 92%, and potential gap 0.837 V for 150 h for the ZAB with a hybrid catalyst of Pt/C + RuO 2. It is hypothesized that the ZAB with the novel hybrid catalyst exhibits its excellent catalytic activity and durability as a result of the synergistic effect of the catalyst's embedded heteroatoms and nitrogen–metal/carbon framework that enhances the ORR/OER performance, porous carbon nano-framework that enables rapid diffusion and electrical conduction, and carbon nanotubes that complete the external electrical connection between the catalysts. [ABSTRACT FROM AUTHOR]

• Development of lithium-metal-based anodes based on Li infusion technique is reviewed. • Several three-dimensional substrates designed to withhold molten Li are discussed. • The roles of porosity, lithiophilicity, and conductivity for anodes are discussed. • Unsolved issues and further research considerations are summarized. Lithium-metal-based anodes (LMA) are known to be most propitious for high-energy rechargeable batteries owing to their extremely high theoretical specific capacity (3860 mAh/g) and low electrode potential. Despite this, uncontrollable dendrite growth and large volume change are regarded as the main barriers to their commercialization. Various approaches for anode modification have been proposed to overcome these barriers. Unfortunately, the formation of short filamentous dendrites with various morphologies is still a problem to be addressed. For constructing stable anodes, lithium infusion is considered to be the most efficient strategy for confining the growth of dendrites and volume change. In this review, we dedicate recent advancements in a variety of porous substrates and their impacts on lithium infusion. We firmly believe that this review could dispense an effective facet for mitigating the mentioned issues and excel the superior performances. [ABSTRACT FROM AUTHOR]

The influence of various sulphur-oxygen (SO) group additives has been investigated in retarding the self-corrosion of Al anode in a 4M KOH solution, in order to effectively enhance the overall performance. The studied additives in this work were all found to be capable of decreasing H 2 evolution, and could mitigate aluminium self-corrosion, with the corrosion inhibition towards the cathodic protection process. The less pitting corrosion and holes were observed for inorganic additives in comparison to the organic counterparts. The Al-air batteries demonstrated an improvement in the discharge capacities: 2604, 2393, 2348 and 2048 mAh g−1 for Na 2 SO 4 , Na 2 SO 3 , C 2 H 6 SO, and C 6 H 5 SO 2 OH, respectively, in comparison to that associated with the 4M KOH (2021 mAh g−1). K 2 S 2 O 8 , an inorganic additive, exhibited a hydrogen evolution efficiency of 21%, but the lowest discharge performance (1973 mAh g−1). This may be due to the instability of the anions in redox reactions. The low inhibition efficiency of the hybrid additives in Al self-corrosion, when compared to single additives, may be ascribed to the involvement of Al3+ in complex formation of the inorganic-organic hybrid additives. A stable discharge-charge cycling test over 6 h with a voltage gap of around 0.7 V is observed for Na 2 SO 4 , demonstrating the efficient performance compared to the additive-free KOH electrolyte. It could be concluded that efficient additives containing SO group, successfully mitigated the self-corrosion and hydrogen evolution associated with the Al anode that was confirmed with DFT results. [ABSTRACT FROM AUTHOR]