•The Ni(OH)2/C composite electrode provides ultrahigh charge-discharge speed of 50C.•The Ni(OH)2/C composite offers a larger discharge specific capacity of 345.2 mAh g−1.•The materials exhibits excellent cycle life during the 20000 cycles.Nickel hydroxide is widely used as cathode materials in metal hydride–Ni (MHNi) and Cd–Ni rechargeable batteries and the asymmetric supercapacitors due to its good electrochemical properties and affordable prices. The specific capacity and cycle life of Ni(OH)2 are greatly declined at high current density due to its P-type semiconductor structure and the mechanism of solid-phase proton diffusion. The paper thus proposes a new controllable complexing–precipitation method to prepare nano-Ni(OH)2 sheets on mesoporous carbon particles, denoted as nano-Ni(OH)2/C composite. Because of the “fusion effect” of the Ni(OH)2 and mesoporous carbon, a sample with 20% carbon can offer 345.2 mAh g−1 at ultrahigh current density of 30 A g−1 which are higher than that of its theoretical one-electron capacity (291 mAh g−1) of Ni(OH)2 during the first 20,000 cycles. Furthermore, the capacity still keeps up to 97% of the initial capacity, which exhibits a superior electrochemical property than the existing Ni(OH)2. The nano-Ni(OH)2/C composite (20% carbon) exhibits a superior electrochemical property than the reported existing Ni(OH)2 and Ni(OH)2/carbon composites in the literature.

•NiFe-LDHs nanosheets are prepared by a new facile and scalable preparation method.•The sample exhibits excellent catalytic activity and stability toward oxygen evolution reaction.•The sample containing 15% Fe exhibits a superior OER performance to 20% Ir/C.Recently, numerous researches have been conducted to develop non-precious metal catalysts for oxygen evolution reaction (OER), among which NiFe oxyhydroxides as the efficient catalysts have been intensively investigated. Herein, we demonstrate NiFe layered double hydroxides (NiFe-LDHs) nanosheets as highly active OER catalysts, which are synthesized by a facile, scalable and template free method. The ordered nanosheets structure of NiFe-LDHs with Fe contents from 0 to 25% was obtained at low temperature with precisely controlled the pH value by complexation-precipitation process. Compared with 20% commercial Ir/C, the obtained sample with 15% Fe exhibits superior catalytic performance in 1 mol L−1 KOH solution. Its overpotential and Tafel slope are, 216 mV and 37 mV dec−1, lower than that of 20% Ir/C (330 mV and 130 mV dec−1) respectively at a current density of 10 mA cm−2. Furthermore, it also exhibits superior stability and durability to 20% Ir/C in 15 h galvanostatic polarization experiments.

•The Pb-O2 fuel cell provides a clean and spontaneous synthetic method for pure α-PbO.•The Pb-O2 fuel cell provides good electrochemical performance in the NaOH solution.•The electrolyte is recyclable after the precipitate process of high pure PbO.•The obtained α-PbO mixed with 60% Shimadzu PbO offers superior capacity and stability.In order to solve the problem of high pollution and high energy consumption of the current lead oxide (PbO) preparation processes, a new clean and energy saving preparation method for high purity α-PbO via discharge of a Pb-O2 fuel cell is reported. The fuel cell with metallic lead anode, oxygen cathode, and 30% NaOH electrolyte can provide a discharge voltage of 0.66–0.38 V corresponding to discharge current range of 5–50 mA cm−2. PbO is precipitated from the NaHPbO2–containing electrolyte through a cooling crystallization process after discharge process, and the XRD patterns indicate the structure is pure α-PbO. The mother liquid after crystallization can be recycled for the next batch. The obtained PbO mixed with 60% Shimadzu PbO is superior to the pure Shimadzu PbO in discharge capacity and cycle ability.

•Carbon nanodots were prepared from NaOH-boiled graphene.•The composite of PdO/CND showed electrocatalytic activity towards EOR.•The catalyst of PdO/CND-0.5M delivered the best electrocatalytic activity for EOR.For the first time, carbon nanodots were prepared from NaOH-boiled graphene. And, a novel catalyst that contained PdO and carbon nanodots (denoted as PdO/CND) was fabricated in this work. In this work, 0.5 M and 1.5 M NaOH solutions were respectively employed with an intention to study the influence of NaOH concentration on the electrocatalytic activity of the obtained catalysts for ethanol oxidation reaction (EOR). The obtained samples were thoroughly characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared spectrometry (FTIR). The results indicated that the intensities of the diffraction peaks for graphene were significantly promoted with increasing the NaOH concentration and carbon nanodots with an average particle size less than 4 nm were fabricated by this developed boiling–grinding–ultrasonication (BGU) method. The electrocatalytic performances of the obtained PdO/CND catalysts for EOR were investigated using cyclic voltammetry (CV) and chronoamperometry (CA). And the consequences strongly demonstrated that PdO/CND prepared from 0.5 M NaOH-boiled graphene showed the best electrocatalytic activity towards EOR among all the prepared catalysts. Developing a very facile method for producing carbon nanodots as well as a novel composite catalyst that contained PdO and carbon nanodots for EOR was the main contribution of this work.

•Spherical α-Ni(OH)2 was synthesized by a green dual complexation-precipitation method.•The electrode offers a large capacity of 457.9 mAh g−1 at high rate of 500 mA g−1.•Al-doped α-Ni(OH)2 shows a good cycling stability in 6 M KOH.The ever-growing demand for energy has greatly stimulated recent researches on developing high-performance materials for nickel-based rechargeable batteries. However, the practical applications of Nickel-base batteries are largely hindered due to lack of high power density and long lifespan of their cathode materials, β-Ni(OH)2. Here, Al-doped α-Ni(OH)2 microspheres comprising densely packed irregular nano sheets have been synthesized via a dual complexation-precipitation (DCP) method. The resulting electrode offers a large specific capacity of 457.9 mAh g−1 at remarkably high rate of 500 mA g−1, which is 47.0% larger than that for β-Ni(OH)2 under the same conditions. In addition, the electrode still keeps 87.0% of the initial capacity after 2000 cycles, displaying excellent cycling performance. The outstanding electrochemical performance benefits from the synergistic contribution of the doped metal ions and the unique hierarchical structure.

In this paper, we present a new efficient composite electrocatalyst, manganese dioxide-supported silver bismuthate (Ag4Bi2O5/MnO2), for oxygen reduction reaction (ORR) in alkaline media. The new electrocatalyst was characterized with scanning electron microscope (SEM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements indicate that the Ag4Bi2O5/MnO2 composite is a very efficient electrocatalyst for ORR in alkaline media. The physical and electrochemical characterization results suggest that the high activity is ascribed to the support effects from MnO2 and the synergetic effects among Ag4Bi2O5 and MnO2. The analysis of rotating disk electrode (RDE) results shows that the ORR occurs via a four-electron pathway on the surface of the Ag4Bi2O5/MnO2 electrocatalyst. This electrocatalyst was further tested in a designed zinc–oxygen (Zn–O2) battery. This battery can offer a discharge time of 225 h at 120 mA cm−2, increasing by more than 492% as compared with pure MnO2 electrocatalyst. It demonstrates that this inexpensive Ag4Bi2O5/MnO2 electrocatalyst is a viable alternative to platinum electrocatalyst for energy conversion devices.

This paper reports a new method of direct recovery of highly pure lead oxide (PbO) from waste lead pastes and lead grids of spent lead–acid batteries via catalytic conversion, desulfurization, and recrystallization processes in sequence. On the basis of the analytical results of lead (Pb) and lead dioxide (PbO2) contents in the scrap lead paste, a certain amount of waste lead grid was used as a reductant to transform the excess PbO2 into lead sulfate (PbSO4). This paper systematically studies the influence of the concentration of sulfuric acid (H2SO4) and catalyst and the reaction temperature on the catalytic process. The desulfurization of the obtained PbSO4 and the recrystallization of PbO in sodium hydroxide (NaOH) solutions of different concentrations are also investigated. Furthermore, electrochemical experimental results show that the prepared α-PbO with high purity provides slightly superior electrochemical performance to the existing lead oxide obtained by the Shimadzu ball-milling method during the first 350 charge–discharge cycles in the cycling test.

In the present paper, we report a novel MnO2 cathode material doped with nano Ag4Bi2O5. The results of characteristic structure indicate that Ag4Bi2O5 is evenly distributed in the MnO2 material and affects the original structure of MnO2. The electrochemical performances of the doped electrode in the alkaline electrolyte are measured by galvanostatic method and cyclic voltammetry tests. Results show that the doped electrode has excellent electrochemical properties and its discharge voltage is 50–100 mV higher than that of the traditional MnO2 electrode. The doped electrode can offer a discharge specific capacity of 481 mAh g−1 at 120 mA g−1. The cycling life of the doped electrode reaches up to 115 cycles, which is 3.4 times longer than that of electrolytic MnO2 electrode at a high current density of 1000 mA g−1. The effect of doping Ag4Bi2O5 is much better than that of doping Bi2O3 or Ag2O independently, which indicates that Ag4Bi2O5 shows more superior electrochemical performance with the assistance of both Ag and Bi cations.

AgCuO2 as ultra fast charging cathode material for alkaline secondary batteries is reported in the present paper. The structural characterization shows that the AgCuO2 material is composed of many one-dimension linear crystals arranged in a certain sequence. The experimental results show that the AgCuO2 electrodes have good electrochemical characteristics at ultra fast charging-discharging speed from 5000 mA g−1 to 50,000 mA g−1. The super high speed ability of charge/discharge makes the charge time of the electrode shorter than 29 s. Cyclic voltammetric (CV) and galvanostatic charge–discharge tests reveal that the charge/discharge process is not the single electron transfer for Cu(III) but the fast dual electron transfer for Ag(II) and Cu(III). The characteristics of high cycling capacity and fast charging for AgCuO2 not only increase the specific capacity of batteries considerably but also make it possible to charge the future electric cars instantaneously as fast as refueling the fuel vehicles.

This paper reports a new lead recovery method, in which high purity metallic Pb is directly produced by electrolyzing PbO obtained from waste lead acid batteries in alkaline solution. The sodium ionic exchange membrane is used to avoid HPbO2− being oxidized to PbO2 on the anode. The new system is not only low energy consuming, but also beneficial to improving the lead recovery efficiency. Furthermore, the new recovery process realizes the circulation of the waste electrolyte, avoiding emission of lead effluent. The effect of concentration of NaOH solution on the cell voltage of the electrolytic bath was studied. Experimental results indicate that the cell voltage of electrolytic bath is 1.23 V, the current efficiency is 99.9%, the lead recovery efficiency is 99.8% and the energy consumption reaches 317 kWh ton Pb− 1 at a current density of 20 mA cm− 2.Highlights► This paper reports a new lead recovery technology by eletrolyzing alkaline PbO solution. ► The appropriate concentration of NaOH in catholyte should be controlled at 15–20%, and that in anolyte at 30%. ► The energy consumption per ton lead is as low as 317 kWh at 20 mA cm− 2. ► The recovery rate of Pb can reach up to 99.8% in the electrolytic process.

Nano Ag4Bi2O5 as a novel cathode material of rechargeable alkaline batteries was successfully synthesized by precise control of precipitation reaction. KOH solution was used as precipitant and a mixture of AgNO3 and Bi(NO3)3 as Ag–Bi source. The experimental results indicate that concentration of KOH, reaction temperature and PH value have the effects on the structure and electrochemical property of the product. The material was characterized by means of XRD, FSEM and TG–DSC. The results show that the sample is single crystals with 50–100 nm in width and 600–800 nm in length. The electrochemical performances of Ag4Bi2O5 in the alkaline electrolyte were measured by galvanostatic method and cyclic voltammetry tests through film electrode. The sample shows three typical procedures during the charge–discharge, corresponding to Ag(II)–Ag(I), Ag(I)–Ag(0) and Bi(III)–Bi(0) transformation processes. This result is also verified by XRD tests. The Ag4Bi2O5 electrode has excellent electrochemical properties. It undergoes a current density as high as 20 A g−1, which greatly reduces charge time down to 55.9 s. The electrode offers a cycling capacity of 330 mAh g−1 and a cycling life more than 400 cycles at 1–2 A g−1.Highlights► Nano Ag4Bi2O5 as a novel cathode material was synthesized. ► The sample shows regular morphology with 50–100 nm in width and 600–800 nm in length. ► The material reduces the charge time down to 55.9 s at a super high current density of 20 A g−1.

A spherical β-Ni(OH)2 product with nano–micro structure was synthesized by a new controllable crystallization complexation precipitation method. The results show that the nano–micro spherical Ni(OH)2 possesses superior electrochemical properties due to its own nano–micro structure. Furthermore, the new samples of cobalt-doped, zinc-doped, and cobalt–zinc codoped Ni(OH)2 with nano–micro structure were also synthesized. The electrochemical properties of these four nano–micro spherical Ni(OH)2 samples were investigated by galvanostatic charge–discharge and cyclic voltammetric (CV) tests. The electrochemical experimental results indicate that the diffusivity of proton of the doped Ni(OH)2 samples is significantly improved as compared with the pure Ni(OH)2 sample. The Co–Zn codoped Ni(OH)2 sample offers a high discharge specific capacity of 257 mA h g–1 and a long life of more than 800 cycles at a super high charge–discharge speed of 50 C, and the charging time of the product is as short as to 1.2 min.

The present paper introduces a new method to prepare nano-NiOOH by oxidizing and cracking spherical Ni(OH)2 of nano-structure in NaClO–NaOH solution. The prepared samples were characterized by X-ray powder diffraction (XRD), field emission scan electronic microscope (FESEM) and transmission electron microscopy (TEM). Results indicate that the synthesized sample is nano-NiOOH rod of 60–150 nm in width. The charge/discharge tests show that the nano-NiOOH cathode shows good cycling reversibility at high current density of 10,000 mA g−1, provides a high capacity of 276 mAh g−1 and reduces the charge time to as short as 1.83 min. Furthermore, the nano-NiOOH still keeps a reversible capacity of 93.7% after 120 cycles at a super high charge/discharge current of 10,000 mA g−1, showing a good charge/discharge property.

The present paper reports the synthesis of the high capacity NiOOH through oxidization of spherical Ni(OH)2 by utilizing high-density NaClO-NaOH solution. The relationship between the structure and the change in electrochemical behavior during the synthesis process of NiOOH was investigated by means of the tests of FSEM, XRD, CV and galvanostatic discharge method. During most oxidizing time, the increment of NiOOH capacity is in linear relationship with the reaction time and is restrained by surface area and the diffusion of protons in solid phase. The optimal reaction time to synthesize ideal spherical NiOOH is 3 h. The appearance of a small platform at 1.2 V in discharging process and the cracks detected by FSEM of NiOOH during reaction process are the evidence of complete oxidization of spherical Ni(OH)2.

A new single flow alkaline battery, Zn–K2[Zn(OH)]4–O2 battery, in which electrodeposited zinc is employed as an negative electrode and the oxygen in atmosphere as an high-capacity positive electrode active material is developed. The working process of the battery only depends on the circulation of a single electrolyte solution with assistance of a single pump and no cationic membrane is needed. The newly designed dual catalytical layers of composite oxygen electrode employs nano-structured Ni(OH)2 and the electrolytic manganese dioxide doped with NaBiO3 as two types of novel highly-efficient catalysts for oxygen evolution and reduction process, respectively. Cell (grade 1000 mAh) test results show that high efficiency is achieved with an average coulombic efficiency of 97.4% and an energy efficiency of 72.2% in 150 cycles.

The present paper reports a new single flow acid battery, Cu–H2SO4–PbO2 battery, in which smooth graphite is employed as negative electrode, lead dioxide as positive electrode and the intermixture of H2SO4–CuSO4 as electrolyte. The reaction Cu⇌Cu2+ takes place on the negative electrode. The working process of the battery is only the circulation of H2SO4–CuSO4 intermixture by means of a single pump. No cationic membrane is needed. A miniature acidic copper single flow battery with a rated capacity of 2000 mAh can offer a discharge voltage of 1.29 V, an average coulombic efficiency of 97% and an energy efficiency of 83% during 450 cycles at a charge/discharge current of 1000 mA.

An investigation was performed on the suitability of carbon materials, metallic lead and its alloys as substrates for zinc negative electrode in acid PbO2–Zn single flow batteries. The zinc deposition process was carried out in the medium of 1 mol·L− 1 H2SO4 at room temperature. No maximum current appears on the potentiostatic current transients for the zinc deposition on lead and its alloys. With increasing overpotential, the progressive nucleation turns to be a 3D-instantaneous nucleation process for the resin-graphite composite. Hydrogen evolution on the graphite composite is effectively suppressed with the doping of a polymer resin. The hydrogen evolution reaction on the lead is relatively weak, while on the lead alloys, it becomes serious to a certain degree. Although the exchange current density of zinc deposition and dissolution process on the graphite composite is relatively low, the zinc corrosion is weakened to a great extent. With the increase of deposition time, zinc deposits are more compact. The cyclings of zinc galvanostatic charge–discharge on the graphite composite provide more than 90% of coulombic and 80% of energy efficiencies, and exhibit superior cycling stability during the first 10 cycles.Download full-size image