•A series of Na-doping LiNi0.5Co0.2Mn0.3O2 materials are synthesized by co-precipitation method.•Proper sodium doping is beneficial for the material properties improvement.•Besides enlarging the Li slab, the introduced sodium can weaken the LiO band in the material.•Na-doping can improve the thermal stability of the LiNi0.5Co0.2Mn0.3O2 material.Na-doped Ni-rich layered oxide LiNi0.5Co0.2Mn0.3O2 cathode materials are synthesized via co-precipitation method in this work. The crystal structure, thermal stability as well as electrochemical performance are studied. Results show that when the Na-doping amount is less than and equal to 2%, the samples can exhibit better electrochemical performance than the parent compound. One reason is that the Na doping can reduce the cationic mixing in the compound, as confirmed by X-Ray powder diffraction (XRD). Beside, results from X-ray photoelectron spectroscopy (XPS) and galvanostatic intermittent titration technique (GITT) show that the introduced sodium can also impact the chemical environment of lithium, making the latter become more easily de-intercalated from the bulk material. However, as the Na-doping amount increases, the electrochemical properties of the samples were deteriorated. Furthermore, results from differential scanning calorimetry (DSC) measurement indicate that the added Na+ is also beneficial for improving the thermal stability of the layered oxide.

•A novel ultrasonic/microwave assisted co-precipitation method was proposed to synthesize lithium-rich material.•We compared the as-prepared sample with that from traditional co-precipitation method.•The sample shows better performances.Ultrasonic/microwave-assisted co-precipitation method (UMCP) is proposed to synthesize lithium-rich material, Li1.1Mn0.433Ni0.233Co0.233O2. The synthesized precursors from UMCP were denser, and the final products showed improved crystallinity, as well as lower cation disordering, caused by the homogeneous dispersed reagents introduced by the ultrasonic effect, resulting in higher discharge capacity and better cycling performance compared with those from traditional co-precipitation method. The sample synthesized by UMCP exhibited a capacity of 260 mAh g−1 at 0.1 C charge/discharge rate and 207 mAh g−1 after 50 cycles, while the discharge capacity of the control sample was only 212 mAh g−1 for the first cycle and 180 mAh g−1 after 20 cycles.

The gel electrolyte is a key factor affecting the performance of lead-acid batteries. Two conventional gelators, colloidal and fumed silica, are investigated. A novel gel electrolyte is prepared by mixing the gelators with sulphuric acid. The physical property testing demonstrates that the mixed gel electrolyte is more mobile, has a longer gelling time, greater stability and a better crosslinking structure than its counterparts as compared with any single gelling agent. The electrochemical properties indicate that the mixed gel electrolyte can suppress the oxygen evolution reaction, reduce the resistance to charge transfer at open circuit potential, increase the initial capacity, demonstrating that it is a promising gel electrolyte for lead acid batteries.Highlights► The viscosity of the new gel electrolyte was significantly improved. ► A longer gelling time was indicated in the novel gel. ► The mixing of two gelators can inhibit the oxygen evolution reaction. ► The initial capacity is increased by twenty percent in the gel battery with mixed gel electrolyte under the same conditions. ► When gelling agents are mixed in a certain proportion, an appropriate three-dimensional gel structure is formed, entrapping more sulfuric acid electrolyte.

The effect of the rare earth element lanthanum (La) on the microstructure of lead–calcium grid alloys was studied by the metallographic microscope. A comparison of the electrochemical corrosion behavior of the new and traditional grid alloys was investigated by cyclic voltammetry (CV), A.C. impedance and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to study the surface morphology of anodic films of Pb–Ca–Sn–Al–Re alloys formed in sulfuric acid solution at 1.3 and 0.9 V for 2 h. The morphology of the corrosion layer was analyzed by SEM after the constant current corrosion test. The results show that an appropriate content of La can effectively (1) increase the fineness of the grain of Pb–Ca–Sn–Al alloys, (2) increase the growth of PbO2 film, and (3) make the anodic film formed at 1.3 V become fine and compact. Alloys with contents of 0.01 wt.%, 0.03 wt.% and 0.1 wt.% La were shown satisfactory results. La also can decrease the growth of Pb(II) film, purify and increase the density of the anodic film at 0.9 V, especially for La content of 0.03 wt.% and 0.1 wt.%. Moreover, La can improve the corrosion resistance of Pb–Ca–Sn–Al alloys, particularly for a La content of 0.01 wt.%.Highlights► We have prepared a novel Pb–Ca–Sn–Al–La alloy, the fineness of the grain was increased by La. ► The La to Pb–Ca–Sn–Al alloy can increase the growth of PbO2, fine and compact anodic film at 1.3 V. ► The La can decrease the growth of Pb(II) at 0.9 V, clear and increase the density of the anodic film. ► La can increase the growth of dendritic crystals, improve the corrosion resistance of Pb–Ca–Sn–Al alloys.

A series of Pb–Na alloys were synthesized by adding sodium to lead. Linear sweep voltammetry (LSV), cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), and other analytical methods were used to investigate the electrochemical performances of the Pb–Na alloys in 1.28 g cm−3 H2SO4 solution. The results indicate that the addition of sodium reduces the generation of PbO and PbSO4 greatly during anodic process, inhibits the oxygen evolution reaction and accelerates the evolution of hydrogen, and the Pb–Na alloys have good cycle performance and corrosion resistance properties. The alloys retain the merits, whilst removing the flaws, of the pure grid, thereby providing a promising positive grid alloy for spirally wound lead acid batteries.Highlights► Sodium decreases the generation of PbO and PbSO4 during anodic process. ► Sodium inhibits the oxidation and corrosion on the Pb electrode effectively. ► Lead–sodium increases the resistance to oxygen evolution. ► Lead–sodium is suitable as the positive plate material in lead-acid batteries.

The effects of different lanthanum content (0, 0.00600, 0.0112, 0.0195 and 0.0540 wt.%) on the electrochemical behavior of lead–lanthanum alloy in sulfuric acid solutions were investigated by linear potential sweep (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The morphology of the corrosion layer and corrosion section of Pb and Pb–La alloys were analyzed by scanning electron microscope (SEM) after corrosion testing. It was found that the addition of La inhibits the oxygen evolution reaction on the surface of Pb alloy electrodes, and La amounts of 0.00600 and 0.0540 wt.% in Pb–La alloy electrodes can lead to a more effective inhibition. The results of the LSV, CV and EIS experiments show that the addition of La can inhibit the growth of the anodic Pb(II) oxides and PbO2 film. The resistance of the anodic film on the Pb–La electrodes is much lower than that on the Pb electrode. SEM for the corrosion layer indicates that the corrosion product on pure Pb and Pb–0.0195% La alloy is uniform and compact. The corrosion products on the alloys with La contents of 0.00600, 0.0112 and 0.0540 are loose and porous that the active materials can easily sit in the apertures to contact the grid surface intimately with the effective. The results demonstrate that Pb–La alloys show the potential for application as the positive grid material in maintenance-free lead-acid batteries.

Policies and laws encouraging the development of renewable energy systems in China have led to rapid progress in the past 2 years, particularly in the solar cell (photovoltaic) industry. The development of the photovoltaic (PV) and wind power markets in China is outlined in this paper, with emphasis on the utilization of lead-acid batteries. The storage battery is a key component of PV/wind power systems, yet many deficiencies remain to be resolved. Some experimental results are presented, along with examples of potential applications of valve regulated lead-acid (VRLA) batteries, both the absorbed glass mat (AGM) and gelled types.

A detailed investigation of the effects on the microstructure and electrochemical properties of lead–calcium–tin–aluminum alloys of adding tin and calcium was undertaken. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) were used to study the anode electrochemical behavior (such as the growth of lead dioxide, a passive film and the evolution of oxygen) of the lead grid alloy in sulfuric acid solution. The structure and corrosion morphology of the lead alloy were observed and analyzed using a polarizing microscope, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The experimental results show that the grains gradually became smaller as the content of calcium increased, and the content of tin decreased, in the alloy. The size and shape of grains were related to the ratio of tin to calcium content in the alloys. The linear sweep voltammetry and AC impedance measurements suggested that the preferred ratio of tin to calcium content, r, is between 9 and 15, and the optimum range of tin content in the alloys is 0.8–1.1%.

The effects of three types of fumed silica on the electrochemical properties of gelled electrolytes have been investigated by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), transmission electron microscope (TEM) and the Brunauer, Emmett and Teller (BET) technique. The CV and EIS results show that a moderate mechanical dispersion of fumed silica in the H2SO4 solution has important effects on the electrochemical properties of the gelled electrolyte. The optimal mechanical dispersion time is closely related to the operating temperature during preparation of gel, as well as the silica particle size and its distribution. A high stirring rate improves the electrode capacity and decreases the viscosity of the gelled electrolyte. With moderate mechanical dispersion, gelled electrolytes prepared from different fumed silica particles exhibit equal electrode capacities.

The influence of the rare earth metal, samarium, as an alloying additive on the electrochemical behaviour of pure lead is studied by means of X-ray diffraction, self-depassivation, linear sweep voltammetry and a.c. impedance spectroscopy in 4.87 M H2SO4 at 25 °C. Studies on Pb–Sm alloys (Sm = 0.02, 0.04, and 0.12 wt.%) indicate that the oxide film formed on the alloy surface at 0.9 V is thicker than that on pure lead when the alloy contained less than 0.1 wt.% Sm. In addition, samarium exercises little influence on the conversion of PbSO4 to PbO2 in the oxide film during charging. The electrochemical impedance of the oxide film is much larger than that of the oxide formed on pure lead. With the addition of more than 0.1% Sm, however, the oxide film on the alloy surface is thinner and samarium obviously promotes the conversion of passive PbSO4 in oxide film to conductive PbO2. The a.c. impedance data show that a high content of samarium greatly inhibits the growth of the passivation layer and decreases the electrochemical impedance of the film.

The influence of the content of SiO2 (in the form of a soot) on the capacity and the self-discharge of lead–acid batteries, as well as on the structure of gelled-electrolyte, is studied in detail by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy and scanning electron microscopy. The content of SiO2 and the viscosity of the gelled-electrolyte are important factors which affect the capacity of batteries. A comparison of cyclic voltammograms indicates a change in the electrochemical behaviour of the lead electrode in the presence of SiO2. The reaction resistance increases as a function of the SiO2 content. The mechanism of the effect of the content of silica soot on electrode capacity and on the performance of gelled-electrolyte is discussed.