| In recent years,the e-bike industry has achievedrapid development in China,and the number of nationwide e-bikes has exceeded 250 million.As the core component of e-bike,lead-acid battery is the biggest contributor to the green travel with annual consumption reaching more than 1 billion.However,the service life of lead-acid battery used in e-bike is only about one year,and the return rate has been up to 10%?20%due to the battery failure.Therefore,it is particularly important to solve the problem of deep cycle service life of lead-acid battery,which can not only reduce the material usage and energy consumption,but also reduce loss result from the return and replacement,thus creating huge benefits for enterprises and society.This investigation is based on the existing technology quality problems of lead-acid battery in e-bike,andaimedatthe capacity attenuation for valve-controlled lead-acid battery.From the perspective of ion migration issues,influenceof metal ion migration behavior by proton exchange membrane materials has beenstudied.Adopting the doping of inorganic gas phase silica to improve the proton conductivity.Using lead antimony alloy solve the problem of poor deep cycle performance of grid corrosion layer.Using bismuth doping is applied to improve the positive active material conductivity and skeletal structure stability during deep cycle process.In this work,the cathode hydrogen evolution problem caused by the metal ions migrated to negative electrode has been proposed a solution.The mechanism of bismuth and antimony doping to improve the structural stability of positive active substances and enhance the battery capacity has been intensively studied.In order to improve the structural stability and electrical conductivity in the cycling process,bismuth and antimony doped lead oxide were sintered at high temperature and applied into the active substances.The results show that antimony and bismuth can enter the lead lattice after sintering at 450?.After bismuth doping,the content of?-Pb O2 in the formed mature plate possesses a maximum value at 1.0%doping,while antimony doping has little influence on the performance parameters of the raw plate and the mature plate,and 1.0%bismuth doping can reduce the conversion voltage to 100 m V.The battery with 1.0%bismuth doping has the highest discharge capacity,which is increased by 2.0%compared with 1.0%antimony doping and 8.7%compared with undoped blank battery.The 1.0%bismuth doped battery has the highest deep cycle life with an initial capacity of 90%after 250 cycles,the 1.0%antimony doped battery has an initial capacity of 80%after 250 cycles,and the undoped battery has a capacity of less than 70%after 250 cycles.It was found that lead discharged before bismuth after bismuth doping,and bismuth could keep the structure stable during charging and discharging.Thermogravimetric study shows that bismuth and antimony doping can increase the water content of electrochemical lead dioxide structure,and thus affect the discharge capacity of lead dioxide electrode.The influence of temperature,forced convection and electric field on the diffusion coefficient and electric field factor of antimony ions in the proton exchange membrane was verified by using proton exchange membrane to prevent the antimony ions from migrating to the negative electrode.The experiments show that the proton exchange membrane can effectively prevent the migration of antimony ions.Under the electric field of 1 V,only 0.018mol·L-1 Sb3+can pass through the proton exchange membrane after 48 hours under the condition at 50 ? and sulfuric acid electrolyte.Proton exchange membranes can prevent more than 95%of antimony ions from transmembrane migration under the same conditions under the combined effect of diffusion and electric field.The proton exchange membrane electrochemical window above 2.8 V conforms to the requirements of the lead-acid battery.The battery internal resistance is affected by proton exchange membrane with a 5.4%decrease in proton conductivity,a 4.6%increase in battery internal resistance,and a 7.0%decrease in C2capacity with 30 microns PEM compared to AGM.Based on the investigation on deep cycle life of battery,it can be found that 93%initial capacity maintains after circular250 times using proton exchange membrane cells antimony and lead plate grid alloy,and 80%for blank cells after circular 250 times.This indicates that the deep cycle life of the battery can be improved by using proton exchange membrane to prevent antimony ion migration.In order to solve the problem of proton conductivity of proton exchange membrane,gas-phase SiO2 doped proton exchange membrane was used to study the influence of SiO2 doping content on the performance of proton exchange membrane,and the influence of modified thickness,temperature,forced convection and electric field on the inhibition of antimony ion migration.The results show that the modified proton exchange membrane has the best performance when the doping amount at6.0%,and can effectively prevent the transmembrane migration of more than 97%antimony ions under the experimental conditions.When the doping content was 6.0%,the water absorption rate increased by 33.2%,ionic conductivity increased by 16.9%,resistance decreased by 1.81%,discharge capacity increased by 1.3%.The decomposition temperature of the modified proton exchange membrane is above 200?,which can meet the requirements of lead-acid battery.The modified proton exchange membrane battery has an initial capacity of 91%after 257 cycles,and the undoped modified battery has an initial capacity of 87%,indicating that the doping modified proton exchange membrane can improve the deep cycle life of the battery.In order to further solve the problem of battery hydrothermal loss caused by metal ion migration to the negative electrode,the effect of p-nitrobenzoic acid on the performance of hydrogen evolution from the negative electrode was studied.The study shows that the addition of 0.010%p-nitrobenzoic acid can increase the hydrogen development overpotential by 26m V.With the addition of 0.01%,the charging acceptance capacity and low-temperature performance reach the maximum value.The charging acceptance capacity reaches 3.33,0.51 higher than the blank,and the low-temperature discharge capacity at-10 ? and-18 ? increases by 2.5%and6.6%respectively.The blank battery attenuates to less than 75%of the initial capacity,indicating that the addition of p-nitrobenzoic acid is beneficial to the improvement of the negative cycle life of the battery under the condition of negative control capacity. |
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