Research Of Improving The Positive Electrode Performance Of Lead Acid Batteries

Lead-acid battery had a history of 152 years since it was been invented in 1859,but it's still one of the most widely used secondary power sources in nowadays because of its excellent characteristics.Although its manufacturing technology is well established,the specific energy actually achieved is low.In this paper we tried to improve the lead-acid battery's performance by preparing different active material plates and using additives.XRD and SEM technology have been used to reveal the effect of paste mixing and plates curing conditions on the active material phases,structure and particle size.The experiment results showed that the main material phase was tri-basic lead sulfate(3BS)at 40 ? mixing and 50?curing,and the crystal particles had a size of about 3 ?m.A mixture of 3BS and tetra-basic lead sulfate(4BS)obtained at 40? mixing and 85? curing,and its larger crystal was about 5 ?m long.The 4BS paste was obtained at 80? semi-suspension mixing and 50? curing,and the crystal particles had a size of about 6 ?m,particles of 10 ?m size were also found.The positive plate obtained at 80 ? mixing and 50 ? curing had the best strength,although its premature capacity was lower than other plates and the specific capacity was 45mAh/g,its capacity retention performance was better than other plates.Hollow glass microspheres(HGM)was added into the positive plate as an additive,the experiment results showed that the addition of HGM increased the resistance of the plate and the formation time relatively,but decreased the PbO2 content in the formed plates,the amount reached 10%with 5%HGM.The electrode with 1%and 3%HGM content had a largest reduction current,which reflect that they could improve the electrode reactivity.About 7%utilization of PAM reached at high-rate discharge conditions with 3%HGM content,but the extent is not obvious at low-rate discharge conditions.The specific capacity was 51mAh/g at 2h rate with 3%HGM,which had a increase of 10.9%when compared to the plate without HGM.Moreover,HGM maintained its good sphere structure after hundreds of charge-discharge cycles and have no adverse effect to the prepared batteries.Carbon Nanotubes(CNTs)was added into the positive plate as an additive,the results showed that the addition of CNTs decreased the resistance of the plate and the formation time,but increased the PbO2 content in the formed plates,the amount reached 11%with 0.8%CNTs.Cyclic voltammetry showed that the reduction current increased along with the addition of CNTs,which reflect that they could improve the electrode reactivity.At low-rate discharge conditions the maximum PAM utilization of 6.4%occurred with 0.8%CNTs content,but at high-rate discharge conditions only 5%occurred with 0.4%CNTs content.The specific capacity reached 57mAh/g at 2h rate with 0.8%CNTs.The improved utilization with the addition of CNTs can be attributed to its conductivity,it could optimize the PAM particles,increase the specific area of positive electrode and lower the current density of positive electrode.