Herstellung von mit reduziertem Graphenoxid beladenen Bleioxid-Verbundwerkstoffen für Blei-Kohlenstoff-Batterien

07 Jun 2023

Graphene is a new type of two-dimensional structure conductive material, which is composed of a single layer of carbon atoms and its basic structural unit is a six-membered ring structure, which has good chemical stability. Moreover, graphene has a high specific surface area, which not only provides a large reaction interface, but also improves the dispersion of surface nanomaterials. The high conductivity of graphene is conducive to the transfer of electron charge in the electrochemical reaction process; The winding between the graphene sheets can provide the pore structure
conducive to electrolyte penetration and ion diffusion, so the conductive composite material constructed based on graphene as a negative electrode additive can significantly improve the electrochemical performance of lead-acid batteries.

However, due to the low density of graphene materials, carbon floating effect will occur when added to the negative lead paste, which will also lead to the loose combination of lead and carbon. Moreover, the introduction of graphene materials will aggravate the problem of hydrogen evolution in the negative electrode and cause the electrolyte to lose water and dry up, so it needs to be modified composite; At the same time, graphene materials are easy to aggregate and caking, the surface is smooth and inert, which is not conducive to composite with other materials, so it must be effectively functionalized.

Technical features:
The invention provides a preparation method of reduced graphene oxide supported lead oxide composite material for lead carbon battery.

The graphene oxide dispersion is thoroughly mixed with aniline and lead acetate solution (pH value is adjusted with KOH alkali solution), and then added to the reaction kettle for hydrothermal reaction (180℃); Separate the graphene/lead composite hydrogel in the reaction product and wash it with anhydrous ethanol and deionized water; Then it was first condensed -(60℃) and then freeze-dried (vacuum, -60℃) to get the reduced graphene oxide/lead oxide composite aerogel; The reduced GO/lead oxide composite aerogel was calcined under the protection of argon (450℃, 2 hours, heating rate of 5℃/min), and the reduced GO supported lead oxide composite was obtained.

The application method of the obtained RGO supported lead oxide composite material is as follows: the composite material is used as a negative electrode additive, mixed with lead powder, acetylene black, barium sulfate, humic acid, sodium lignin sulfonate, short fiber, deionized water and dilute sulfuric acid, and coated on the lead grid, and the negative electrode generator plate of lead acid battery is obtained after curing.

The reduced graphene oxide in the invention refers to the graphite is intercalated and dispersed by chemical method first, and oxygen-containing functional groups are modified on its surface to form graphite oxide or graphene oxide; And then a strong reducing agent is used to reduce and eliminate the functional groups on the surface to get reduced graphene oxide. The graphene prepared by this method has more surface defects, contains more oxygen-containing functional groups, and is easy to modify the surface. Moreover, this method can realize large-scale production of graphene, and is more suitable for industrial applications than stripping graphene by physical method.

The reduced graphene oxide/lead oxide nanocomposite material prepared by the invention is uniformly loaded with lead oxide particles between the reduced graphene sheets, and the diameter size is controllable between 50300 nm, and the amino or imino functional group in the aniline molecule can effectively adsorb lead ions through electrostatic action and coordination complexation. -Moreover, the nitrogen-containing functional group has reducibility and can be REDOX adsorbed with lead ions with strong oxidizing properties, which enhances the adsorption ability of the graphene oxide sheet to lead ions, increases the active site of the composite material and enriches the performance characteristics of the composite material. The agglomeration of graphene is avoided, and the uniform dispersion of graphene and lead compounds is realized. And improve the density of carbon materials, reduce the phenomenon of floating carbon in the mixing process of graphene and lead anode materials, can significantly improve the charge acceptance capacity of lead-acid batteries and HRPSoC cycle life; At the same time, nitrogen doping and the composite of lead oxide and graphene can effectively increase the hydrogen evolution overpotential of the additive and improve the water loss problem of lead-carbon batteries.

Test data:
The produced negative electrode generator plate and the positive plate of the lead-acid battery were assembled into a liquid-rich battery, and the cycle life and specific capacity of the highrate partially charged condition (HRSoC) were measured and compared (data are shown in Table 1 and Figure 1). The results show that the cycle performance and specific capacity of the lead-carbon battery are significantly improved compared with that of the traditional leadacid battery (blank pair ratio) after the introduction of graphene additives by conventional methods, and the lead-carbon battery with the additive prepared by the invention has further improved in terms of HRPSoC cycle life and specific capacity.

Table 1 . Comparison of performance tests of liquid -rich led-acid batteries

FIG. 2 shows the comparison of hydrogen evolution performance of the prepared n egative generator plate. As can be seen from the figure, the blank without adding graphene material has the highest overpotential for proportional hydrogen evolution, while the common graphene material added in accordance with the common method has the lowest proportional hydrogen evolution overpotential, which is inseparable from the influence of the carbon material itself has a low hydrogen evolution overpotential. However, after adding the reduced graphene oxide/lead oxide additive prepared by the invention, the ratio of hydrogen evolution overpotential of the negative plate is roughly the same as that of the blank pair without the addition of graphene, which proves that the invention can effectively inhibit hydrogen evolution and has a significant effect on slowing down the water loss failure of the battery.