Application Of Low-cost Porous Carbon Matrix Composites In Negative Electrode Of Lead-acid Batteries

Lead-acid batteries is a kind of secondary battery with mature technology,high reliability,high recovery and low price,which is widely used in transportation,electric power,communication,military,energy storage and other fields.Lead-acid battery has excellent electrochemical performance,but due to the irreversible sulfation of electrode active material,the service life of lead-acid battery is short,and the actual specific energy(20?40Wh kg^-1)is far lower than the theoretical specific energy(170 Wh kg^-1).Since entering the 21st century,with the development and application of new carbon materials,the life of lead-acid batteries has been improved to a certain extent,especially the life of batteries has been greatly improved.However,the application of new carbon materials in lead-acid batteries also brings new problems,and more work needs to be done.In this thesis,two kinds of low-cost porous carbon matrix composites are used as additives for the negative electrode of lead-acid battery to improve the irreversible sulfation of the negative active material and the capacity and life of the battery.(1)Carbon nanotube clusters in situ grown on stereotaxically-constructed graphene(SCG-CNTs)are prepared by one-step catalytic pyrolysis of transition metals.Then SCG-CNTs are used as additives to improve the irreversible sulfation of negative active material of lead-acid batteries,so as to improve the specific capacity of negative active material and the cycle life of the battery.The specific capacity of the negative active material of battery with SCG-CNTs(176 m Ah g^-1)is increased by 23%compared to the commercial battery(143 m Ah g^-1).The cycle life of the battery with SCG-CNTs at high rate part state of charge(HRPSo C)(42946cycles)is 154%higher than that of conventional commercial batteries(16888 cycles)due to the formation of micro conductive junction like structure of SCG-CNTs in the negative active material.(2)Firstly,the silkworm excrement-based porous carbon(SEPC)is prepared by one-step catalytic pyrolysis of transition metals.Then,SEPC is used as a reducing agent to reduce the negative active materials of waste lead-acid batteries to obtain the silkworm excrement based porous carbon materials loaded with lead oxide particles(SEPC-Pb O).The affinity between the SEPC loaded with Pb O and the negative active material is greatly improved,which reduces the difficulty of mixing lead paste and carbon material.In the process of repeated charge and discharge,the Pb O of SEPC load is gradually converted to Pb SO₄,which inhibits the hydrogen evolution ability of the SEPC.Batteries performance tests showed that the sepcific capacity of the negative active material of battery with SEPC-Pb O(165 m Ah g^-1)is 15%higher than that of the commercial battery(143 m Ah g^-1),and the capacity retention rate for 400 cycle at 100%discharge of depth(DOD)cycles is up to 84%...