Study On The Modification Of Negative Plates For Lead Acid Batteries And Assembly Of An Acid-Free Lead-Sodium Hybrid Battery System

Lead acid batteries, as the most frequently used rechargeable batteries, have been widely used in military, communications, industrial and civil mobile equipment and vehicles for more than 150 years. Though many new battery technologies are emerging in present days, the demand for the century-old lead acid batteries is still continuously increasing and they still occupy the largest battery market share in the world. The main reasons are their unique properties of low cost, high safety and easy recycling. However, lead acid batteries still suffer from several drawbacks which restrict their practical application and further development. Firstly, the energy density is relatively low which cannot meet the demand for electrical vehicle and large-scale energy storage system. Secondly, the cycling performance is poor because of the sulfation on the negative plates, especially under the high-rate partial state of charge(HRPSoC, operation condition of HEV) condition. Thirdly, sulphuric acid electrolyte and lead electrode material can be harmful to environment and human body. Therefore, it is urgently needed to solve the existing problems of lead acid batteries. This paper focuses on improving the performance of lead acid batteries by adding additives and modified carbon materials to the negative plates. In addition, we also propose an acid-free lead-sodium hybrid battery system with excellent performance. The details are as follows:(1) Investigating the effects of two additives-modified staple fibers and porous hollow glass microspheres(PHGMs) on the performance of negative plates in lead acid batteries. The modified staple fibers can increase the electronic conductivity of the active material and improve the whole conductive network of the plates, while the PHGMs can improve the porosity and facilitate electrolyte diffusion of the plates. And the utilization of active materials and cycling performance of the batteries could be improved with the addition of these two additives.(2) Investigating the effects of carbon materials and modified carbon materials on the performance of lead acid batteries. We can inhibit the hydrogen evolution on the carbon materials and improve the electrochemical performance of lead acid batteries by modification of carbon materials. Firstly, the bismuth element is used to modify the commercial activated carbon, which can greatly reduce the hydrogen evolution rate. However, the addition of carbon materials can not only cause serious hydrogen evolution. And in this way we load the nano PbO on the carbon material by in-situ method. Pb is a kind of element with high hydrogen evolution overpotential. After modification by PbO, the hydrogen evolution overpotertial of carbon material could be improved obviously. Moreover, the PbO can also increase the affinity between carbon material and Pb electrode material, which means they can be mixed well during the paste process.(3) A novel acid-free lead-sodium hybrid battery is assembled by using lead/activated carbon(Pb/AC) composite as the anode and copper-nickel hexacyanoferrate(CuNiHCF) as the cathode in 1 M Na2SO4 aqueous electrolyte based on the existing technical process. The key factors for the new battery system could be summarized from four aspects:(1) a clear energy storage mechanism;(2) excellent cycling stability and rate capability;(3) high energy density;(4) less environmental pollution and low cost.