Research On Application Of Rice Husk Carbon-based Additive In Starting And Stopping The Negative Electrode Of Lead-carbon Batteries

In hybrid electric vehicles（HEVs）,start-stop batteries need to operate from a partial baseline state of charge while providing high current discharge and accepting fast charging.In this application condition,sulfation will occur on the negative plate of lead-acid battery,resulting in electrode failure.Studies have shown that negative sulfation can be effectively improved by the addition of carbon-based materials,so scholars call the lead-acid battery with carbon-based materials added to the negative electrode as lead-carbon batteries（LCBs）.However,due to the lower potential than the theoretical value during the electrochemical reaction of carbon materials,the negative plate of lead-carbon battery will have serious hydrogen evolution,which leads to premature battery failure due to water loss of electrolyte.Biomass rice husk carbon-based materials are widely used as additives for lead-acid batteries because of their abundant raw materials,simple preparation method,low cost,abundant porous structure and large specific surface area（SSA）.In addition,researchers further developed a new lead carbon composite material to improve the hydrogen evolution overpotential of rice husk carbon material and inhibit the water loss of electrolyte.In order to improve the cycle life and dynamic charging acceptability of start-stop lead carbon batteries,the performance of start-stop lead-carbon batteries was improved by selecting and optimizing rice husk carbon based additive and its formula.The main work of this paper is as follows:（1）Firstly,mixed carbon（MBH）,rice husk activated carbon（RHAC）and two kinds of lead carbon compounds(Pb O@RHAC and Pb O_1-x@RHAC)were added to the negative electrode of start-stop battery with 1%content respectively,and the performance stability was compared by testing the start-stop cycle life,dynamic charging acceptance and low-temperature starting ability of the battery.It indicates that biomass rice husk-based activated carbon material can improve the start-stop battery performance,and the lead-carbon composite Pb O_1-x@RHAC corresponds to the best start-stop battery performance.（2）In order to study the mechanism of action of rice husk carbon-based materials as negative additives for start-stop batteries,p Hysical tests and electrochemical characterization of various additives and corresponding electrodes were conducted.The results show that Pb O_1-x@RHAC composite has a large specific surface area of electrical conductivity and electrochemical activity,which is conducive to promoting the reversible conversion between Pb and Pb SO₄,providing additional nucleation sites for electrochemical reactions and inhibiting the deposition of large Pb SO₄.Secondly,the electrode corresponding to Pb O_1-x@RHAC composite material has the lowest electron mass transfer resistance,which is beneficial to promote proton transfer and reduce the pHysical and electrochemical polarization of the electrochemical mass transfer process.Compared with MBH and RHAC materials,the hydrogen evolution overpotential of Pb O_1-x@RHAC and Pb O@RHAC materials was increased to different degrees,which inhibited the hydrogen evolution of electrolyte.（3）Taking PbO_1-x@RHAC composite material with the best performance as the research object,the addition amount of it in the negative electrode of start-stop battery was studied.The electrochemical characterization of different electrodes was conducted by setting the content gradient.The results showed that the electrode with the content of 1.5%had the largest specific surface area and the lowest mass transfer resistance.In order to study the effect of additive amount on battery performance,the battery was tested by start-stop application.The test results show that when the addition amount is1.5%,the dynamic charging acceptance capacity of the battery is the highest,and the start-stop cycle life reaches 59,258 times,reaching the advanced level in the field of start-stop battery in China.