The Research Of Lead Carbon Electrochemical Energy Storage Systems

Electrochemical energy storage systems have been widely used in portable electronic devices,hybrid electric vehicles,electric vehicles,automobiles and renewable energy storage.In the 21 st century,with the development of electric vehicles,hybrid electric vehicles and renewable energy storage,high power requirements have been put forward on electrochemical energy storage?EES?devices.Lead and carbon are two relatively abundant and cheap elements used in EES.The elementary substance and compounds of lead and carbon can be made into several electrochemical energy storage devices,such as C/C electric double layer capacitor?EDLC?,PbO₂/AC asymmetric electrochemical capacitor?AEC?and lead-carbon battery.EDLC has the characteristics of high charge-discharge power,short response time and long cycle life.However,the price of activated carbon is still very high and the pore size distribution is narrow.PbO₂/AC AEC is a kind of hybrid energy storage device,which is of high power and low price.It has enormous potential to be used in the peak-shaving and frequency regulation of electric grid.The cycle life of PbO₂/AC AEC depends mostly on the PbO₂ positive electrode,hence the cycle life of PbO₂ should be extended.Lead carbon battery is a kind of modified lead acid battery by carbon materials.Lead carbon battery has the characteristics of low price and and mature manufacturing technology,and has enhanced charge power and further enhanced cycle life at partial state of charge operation,which is suitable for the storage of electricity generated by renewable energy.This paper focuses on the crucial issues in the development of EDLC,PbO₂/AC AEC and lead carbon battery,studied the factors influencing the performance of PbO₂ electrode,assembled the PbO₂/AC AEC with high energy density,discussed the electrochemical origin of the enhanced charge acceptance of lead-carbon electrode,proposed a method for the preparation of 3D hierarchical porous carbon,and applied a kind of rice husk carbon in the construction of lead carbon electrode,while used this electrode in the partial state of charge operations.The conclusions are as follows.?1?Three-dimensional porous titanium based PbO₂ electrode?3D-Ti/PbO₂?was prepared by galvanostatic electrodeposition method.Through the optimization of preparation parameters,the 3D-Ti/PbO₂ prepared at 1 mA cm^-2 has the largest capacity with a capacity of 132 mAh g^-1 at a high discharge current density of 0.9 A g^-1.The factors that influencing the performance of 3D-Ti/PbO₂ were studied by scanning electron microscopy,voltammetric charge analysis and electrochemical impedance spectroscopy.Results indicate that the PbO₂ electrodes have large capacity and good rate capability should possess high surface area and good connection between the PbO₂ particles.?2?Through the discussion of the electrochemical behavior of 3D-Ti/PbO₂ and AC in sulfuric acid electrolytes,we have assembled the PbO₂/AC AEC wih high energy density.When the mass ratio between AC and PbO₂ is 1.61,3D-Ti/PbO₂/AC AEC has the highest energy density of 49.4 Wh kg^-1,with a specific capacitance of 135 F g^-1 and a power density of 433.2 W kg^-1.When the power density of 3D-Ti/PbO₂/AC AEC reaches 2078 W kg^-1,the energy density still sustains at 30 Wh kg^-1.?3?Physical and electrochemical techniques are applied in the discussion of the role of carbon materials in a lead-carbon composite electrode.Results indicate that,in the charge process of a lead-carbon electrode,the capacity of AC is small;and at the surface of AC,the reduction of PbSO₄ occurs preferentially,which provides electron buffer;meanwhile,the large surface area of carbon provides sites for the growth of Pb branches,so as to contribute the distribution of electrons.In summary,the electrochemical reaction at AC surface contributes mostly to the enhancement of the charge acceptance of lead-carbon electrode.?4?Based on the above-mentioned mechanism,we proposed a facile,simple method to prepare 3D hierarchical porous carbon materials using lignin as precursor,KOH as activation agent and template.Lignin derived hierarchical porous carbon?LHPC?possesses both mesopores and micropores with a 3D skeleton composed with large micron-sized pores.LHPC was further assembled into C/C EDLC.LHPC displays relatively high specific capacitance,good rate capability and long-term cycling stability.LHPC exhibits a capacitance of 165 F g^-1 at 0.05 A g^-1 and 123.5 F g^-1 at 10 A g^-1 in 1 mol L-1 H-2SO₄ aqueous electrolytes.?5?We prepared a lead-carbon electrode with superior performance at partial state of charge?PSoC?operation by using rice derived carbon?RHC?.Traditional Pb electrode was sulfated severely at PSoC operation.Lead-carbon electrode with high surface area porous carbon materials as additive was destroyed by severe hydrogen evolution reaction.The lead-carbon electrode composed of RHC has good cycling stability and high coulombic efficiency at PSoC.The superior performance of lead-carbon electrode composed with RHC was thought to be that the large pores in RHC provide sites for the Pb/PbSO₄ redox couple,which enhances the reversibility of Pb negative electrode.