News

Lead-acid batteries, since the advent of 1859, with low cost, mature technology, high and low temperature performance and deep discharge and other significant advantages, widely used in automotive starting, energy storage system, emergency power supply and many other fields. As the core component of lead-acid battery, the performance of electrode material is directly related to the overall charge and discharge efficiency, cycle life and energy density of the battery. In recent years, with the surge in global demand for efficient and long-life energy storage equipment, researchers have carried out a lot of research on lead-acid battery electrode materials, and are committed to breaking through traditional limitations and promoting lead-acid battery technology to a new height.

1. Characteristics and limitations of traditional electrode materials

(1) Positive electrode material

The active material of the positive electrode of the lead-acid battery is lead dioxide (PbO_2). alpha-PbO_2 and beta-PbO_2 are two common crystal forms. alpha-PbO_2 has higher hardness and stability, while beta-PbO_2 has larger specific surface area and conductivity. The synergies between the two ensure the performance of the positive electrode in the charge and discharge process. In the charging stage, PbSO_4 is gradually transformed into PbO_2, and the following reaction occurs: PbSO_4 + 2H_2O-2e ^ -PBO_2 + 4H^+ + SO_4^2-; When discharging, the process is reversed. However, PbO_2 is easy to soften and fall off during use, resulting in short cycle life of the battery. As the number of charge and discharge cycles increases, the structure of the active material in the positive electrode is gradually destroyed, and the active surface area is reduced, resulting in the attenuation of the battery capacity, which limits the use of lead-acid batteries in applications requiring a long life.

(2) Negative electrode material

The negative active material is spongiform lead (Pb). In the discharge process, Pb loses electrons to form PbSO_4, that is, Pb + SO_4^2 - - 2e^-PbSO_4; When charged, the resulting electrons of PbSO_4 are reconverted into Pb. Lead has good electrical conductivity and low cost, but the negative electrode is prone to hydrogen evolution at the end of the charge, which not only consumes electric energy, reduces the charging efficiency, but also may cause the internal pressure of the battery to rise, affecting the safety of the battery. At the same time, lead sulfate crystals will gradually form on the surface of the negative electrode during the charge and discharge cycle, and if the crystal growth is too large, it will hinder ion transport and further reduce the performance of the battery.

2. Research and development of new electrode materials

(1) New cathode materials

1. ** Composite oxides ** : In order to improve the performance of PbO_2, researchers have tried to compound it with other metal oxides. For example, the PbO_2-MnO_2 composite cathode material is formed by adding MnO_2. MnO_2 has good catalytic activity, which can promote the formation and stability of PbO_2 and inhibit its softening and shedding. The research shows that the proper addition of MnO_2 can prolong the battery cycle life by 20%-30%, and effectively improve the long-term service performance of lead-acid batteries. In the process of charge and discharge, MnO_2 participated in the REDOX reaction, regulated the electron transfer process on the electrode surface, optimized the reaction kinetics of PbO_2, and enhanced the electrode stability.

2. ** Conductive polymer modification ** : The use of conductive polymers such as polyaniline (PANI) to modify PbO_2 electrode has become a research focus. PANI has good electrical conductivity and environmental stability. Coating PANI on the surface of PbO_2 can significantly improve the electron transport rate of the electrode. During the charging and discharging process, PANI can transfer electrons quickly, accelerate the conversion reaction between PbO_2 and PbSO_4, reduce electrode polarization, and improve the charging and discharging efficiency of the battery. Experiments show that the positive electrode modified by PANI can significantly improve the charge and discharge performance of the battery at high rate. Under the condition of high current discharge, the battery capacity retention rate is increased by about 15%-20%, which expands the application range of lead-acid batteries in high-power demand scenarios.

(2) New negative electrode materials

1. ** Lead-based alloy ** : By adding a small amount of other metal elements to the pure lead to form an alloy to improve the negative electrode performance. Such as adding calcium (Ca), tin (Sn) and other elements to form Pb-Ca-Sn $alloy negative electrode. Calcium can reduce the hydrogen evolution overpotential of lead, effectively inhibit the hydrogen evolution reaction, reduce hydrogen production, and improve the charging efficiency. Tin can enhance the mechanical strength of the alloy, improve the corrosion resistance of the electrode, and prevent the negative electrode from being damaged by corrosion during the charge and discharge process. Lead-acid batteries using Pb-Ca-Sn alloy negative electrode increase the cycle life by 30%-40% compared with traditional pure lead negative battery, while reducing maintenance costs, and have broad application prospects in industrial energy storage and other fields.

2. ** Carbon composite ** : The composite of carbon material and lead negative electrode is another effective way to improve the performance of the negative electrode. For example, graphene, which has excellent electrical conductivity and high specific surface area, is combined with lead to form a $Pb-$graphene composite. As a conductive network, graphene can accelerate electron transport, provide more active sites for lead deposition and dissolution, and inhibit the growth and aggregation of lead sulfate crystals. The study found that the addition of an appropriate amount of graphene negative electrode significantly improved the performance of the battery in a low temperature environment, and at -20 ° C, the battery capacity retention rate increased by 25%-35% compared with the traditional lead negative electrode, which greatly enhanced the application adaptability of lead-acid batteries in cold areas.

3. Technical means and development trend of electrode material research

(1) Application of advanced characterization technology

Advanced characterization technology plays a key role in the research of lead-acid battery electrode materials. Scanning electron microscopy (SEM) is used to observe the microscopic morphology of electrode materials, clearly showing the structural changes on the electrode surface, the distribution of active substances and crystal growth, and helping researchers analyze the failure mechanism of electrodes during charging and discharging. X-ray diffraction (XRD) can accurately determine the crystal structure and phase composition of the electrode material, and understand the crystal transformation of the material in different states by analyzing the diffraction pattern, which provides a basis for optimizing the material synthesis process. In addition, electrochemical impedance spectroscopy (EIS) can measure the impedance change of the electrode during charge and discharge, deeply study the electrode reaction kinetics, reveal the hindrance factors in the process of ion transport and electron transfer, and help optimize the performance of new electrode materials.

(2) The trend of interdisciplinary integration

In the future, the research on lead-acid battery electrode materials will show the development trend of multi-disciplinary cross-integration. Materials science, chemistry, physics and other disciplines have collaborated deeply to design and construct new electrode materials from the atomic and molecular levels. For example, using quantum chemistry calculations to simulate the electronic structure and chemical reaction process of electrode materials, predict material properties, guide experimental synthesis, reduce blind trial and error, and accelerate the development process of new materials. At the same time, the concept of bibionics is used to develop self-healing and adaptive electrode materials, mimicking the self-regulation mechanism in the biological body, so that the electrode can automatically repair the damage during the charge and discharge process, maintain stable performance, and open up a new path for the innovative development of lead-acid battery electrode materials.

The research of lead-acid battery electrode materials is constantly breaking through the traditional limitations, and the research and development of new materials and the innovation of technical means have injected new vitality into it. By improving the performance of electrode materials, lead-acid batteries are expected to achieve significant improvements in key indicators such as energy density, cycle life, charge and discharge efficiency, continue to play an important role in the field of energy storage, and expand the market in emerging application scenarios, providing reliable and efficient solutions for global energy storage and conversion needs.