N,P Doped Lead Carbon Battery Cathode Additive Preparation And Battery Performance Study

Lead-carbon batteries have the same properties as traditional lead-acid batteries,such as safety,cheapness and stability.The addition of carbon material in the negative plate can provide capacitive buffer and conductive network for the battery,thus significantly extending the cycle life of the battery in high rate partial charge state(HRPSo C).However,the addition of carbon in the negative electrode will,on the one hand,aggravate the occurrence of hydrogen precipitation reaction,and the generated hydrogen will separate the carbon particles from the lead,which will destroy the structural stability of the negative electrode plate;on the other hand,the uneven mixing of lead and carbon will reduce the connection between the negative electrode active material(lead sponge)and the carbon material during the charging process,which will lead to the aggregation of carbon material,and then lead to the increase of battery resistance,which greatly affects the battery performance.The doping of carbon materials with elements with high hydrogen precipitation potential such as N,P and S can effectively inhibit the occurrence of hydrogen precipitation reactions.In this paper,laminated g-C₃N₄-doped Pb-Carbon composites,N,P-doped Pb-Carbon composites formed by high-temperature carbonization of D418 resin and N,P-doped Pb-Carbon composites formed by high-temperature carbonization of D418 resin after adsorption of Pb were prepared,and the electrochemical properties of the three materials were investigated separately,and the batteries were assembled by using them as anode additives,and the performance of the batteries was investigated.The main research findings are as follows.(1)The graphitic phase carbon nitride(g-C₃N₄)with a specific surface area of 226.58m~2/g lamellae was prepared by high-temperature pyrolysis using urea as the precursor.The negative electrode plates of lead carbon batteries were prepared from g-C₃N₄ at the ratios of0.5%,1%,2%,3%and 4%,and were studied in comparison with the negative electrode plates with the addition amount of 1%activated carbon.The results showed that the g-C₃N₄cathode plate with 1%addition exhibited higher specific capacitance,lower impedance and hydrogen precipitation current.The hydrogen precipitation current(-6.67 A/g)of the 1%g-C₃N₄ anode plate at 1.5 V is only 6%of that of the activated carbon anode plate(-130 A/g);the impedance of 1%g-C₃N₄ and activated carbon anode materials are 1.34?and 47.38?.More importantly,the specific capacitance of 1%g-C₃N₄ anode plate(52 F/g)is higher than that of 1%activated carbon anode plate(11.70 F/g)is 344%higher.The prepared negative plates with different ratios were assembled into batteries according to three positive and two negative to perform cycle life tests under high rate partial charge condition(HRPSo C),and the results showed that the battery with 1%g-C₃N₄ showed a higher cycle life with 600cycles before battery failure(discharge voltage below 1.7 V),which is an increase in service life compared to 370 cycles of the activated carbon group battery 62.16%.The results of failure mechanism analysis showed that the addition of N suppressed the hydrogen precipitation reaction and the lamellar structure improved the compatibility of lead and carbon,enabling g-C₃N₄ to be more uniformly distributed in the anode active material.(2)N,P-doped resin carbon materials(N,P/RC)were prepared by high-temperature carbonization under N2 protection using D418 macroporous chelate resin as the precursor,and their structures were characterized by XRD,SEM and FTIR.The negative electrode plates of lead carbon batteries were prepared by N,P/RC at the ratios of 0.1%,0.5%,1%,1.5%and 2%,and were studied in comparison with the negative electrode plates with the addition amount of 1%activated carbon.The results showed that the N,P/RC negative plates with 1%addition showed excellent electrochemical performance with high specific capacitance(71.45 F/g),low hydrogen precipitation current(11.12 A/g at 1.5 V)and small impedance(33.60?).The negative plates were assembled into a battery with three positive and two negative plates to show a high initial capacity of 13.69 Ah at 0.5A constant current discharge and 14.09 Ah at 1A constant current discharge,while the activated carbon group only had 12.44 Ah and 12.68 Ah.The 10-h charge/discharge curves clearly showed that the battery with N and P/RC added had a smaller capacity than the battery with The cells with N and P/RC have smaller polarization than those with activated carbon.(3)The N,P-doped resin carbon@Pb composite(N,P/RC@Pb)was prepared by high temperature carbonization after Pb²⁺adsorption by D418 resin,which eliminated the problem of uneven mixing of lead and carbon to some extent.The influencing factors of Pb adsorption by D418 resin and the effect of carbonization temperature on the final product were investigated,and the results showed that the optimum p H for adsorption was 4,and the adsorption efficiency was 96.7%at this time.The adsorption capacity increased from 6.18mg/g to 84.90 mg/g when the initial concentration of adsorption was increased from 20 mg/L to 300 mg/L.The adsorption basically reached the steady state in the first 8 h.The best graphitization of N,P/RC@Pb was prepared at the carbonization temperature of 600°C,when the conductivity was stronger.The prepared N,P/RC@Pb 0.1%,0.5%,1%,1.5%and2%were added to the negative plate of lead carbon battery for cyclic voltammetry,AC impedance and linear cyclic voltammetry tests,and the results showed that the negative plate with 1%addition had a high specific capacitance of 81.75 F/g,impedance of 27.40?and hydrogen precipitation current of-10.50 A/g at-1.5 V.It was more conductive than The electrochemical performance of the negative electrode plate was significantly improved by adding N and P/RC.The negative plates were assembled into a battery according to three positives and two negatives to show a higher initial capacity of 13.95 Ah tested at 0.5A constant current discharge and 14.35 Ah tested at 1A constant current discharge,which is2.5%higher than the initial capacity of the battery with N and P/RC added and 12%higher than the initial capacity of the activated carbon group battery.