| Distributed power plant is an important power facility that new energy to achieve local consumption and coordinated development. The core is on the development of large capacity,high performance and low cost energy storage system. According to the permanence of reversible conversion that Pb2+ in solution store electricity with the form of solid PbO2 and Pb;The low cost of single fluid flow without membrane; The flexibility of power and capacity can be adjusted by the logarithm of electrode and the concentration of Pb2+; The environmental protection of the residual storage layer can be recovered by H2O2 and reach no pollution. So the lead-acid flow battery have caused the high attention of the field of distributed energy storage power station. However, due to the conventional graphite polymer and carbon foam electrodes with the poor conductivity, low specific surface area and lower hydrogen evolution potential. Battery showed severe negative dendrite, insufficient as the less energy storage capacity, the lower and unstable charge-discharge efficiency and so on. Based on these, carbon foam as substrate for electroless copper plating and electrodeposition lead in this paper. Studied systematically the preparation technology, mechanism and correlation property of carbon foam composite coating. Explored the excellent physical/chemical properties and structural characteristics of the carbon foam composite coating electrode compared with graphite and carbon foam, which influence on the storage deposition and properties in the application of lead-acid flow battery and the mechanism of improving battery capacity.Research shows: Carbon foam composite coating be preparated after pretreatment of carbon foam substrate, electroless copper and electrodeposition lead. Reasonable coarsening of matrix can enhance the mechanical contact with copper coating. The middle layer of copper plating can enhanced electrochemical bonding with electrochemical lead plating layer.Electrochemical lead current density of 20 mA/cm2, or other process parameters, which can obtain smooth surface and layer particles. The mechanism of electroless copper plating follows the theory of electrochemistry mixed potential. Analysis from the electrochemical point,electrochemical lead is divided into under potential deposition and over potential deposition.Physical and chemical characteristics field: The coating woth good adhesion tested by thermal cycling method. XRD analysis of the coating without impurity element incorporation.The conductivity of the carbon foam composite coating electrode is 1315.79 s/cm and the electrode current-carrying capacity meet the requirements of 30 ～ 40 mA/cm2 when the thickness of electroless copper plating layer is 3～4 μm ; Copper/lead plating with high toughness can effectively prevent pre-crack massing in weak skeleton. The overall compressive strength increased to 0.5 Mpa; The carbon foam composite coating electrode has better reversibility of electrode reaction by cyclic voltammetry test, and the reversibility of electrode reaction was enhanced with the increase of scanning speed and the number of cycles, Structural characteristics field: The carbon foam composite coating has excellent lightweight porous characteristic with Porosity 93.71%, apparent density 0.663 g/cm3; The real surface area of the carbon foam composite coating is 3～4 times of the graphite plate.The storage layer Pb on the surface of the carbon foam composite coating is more uniform than that on the graphite plate and the carbon foam electrode, and its surface porous structure disperse charge effectively, not easy to produce dendritic crystals. Maybe due to the uniform and dense distribution of the electric field influence on distribution of Hydroxyl radical on positive electrode, the PbO2 storage layer particles are uniform deposition and compact combination. Because of its physical/chemical characteristics and structural characteristics, it has a smaller electrode reaction polarization overpotential and ohmic partial pressure, that the battery charge/discharge coulombic efficiency 93% ～ 95%; voltage efficiency 89% ～ 90%,eenergy efficiency 83%～85%. When the electrode surface capacity reach to 50 mAh/cm2, the coulombic efficiency still stabilize at 96±0.5%, and showed excellent fast charging and discharging performance. |
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