Study On Carbonyl And Imine Organic Compounds In Anode Of New Aqueous Proton Battery

With the promotion of vehicles and rise of new devices,safety and energy density of energy storage devices（such as batteries）have drawn widespread attention.The aqueous proton battery is regarded as a promising next-generation energy storage device due to its advantages such as environmental protection,high safety,and low price.However,the carriers involved in the actual charge/discharge process are hydrated protons（H₃O⁺）in some aqueous proton batteries.Radius of hydrated protons is larger than that of protons,so appropriate electrode materials is indispensable requirement.Organic electrode materials have become one of the popular aqueous proton battery electrode materials due to the advantages of large intermolecular gaps,high theoretical specific capacity,and flexible structure.Because of its fast kinetics,C=O and C=N organic compound electrode materials have attracted widespread attention.This work has studied the electrochemical performance of anode electrode materials containing C=O and C=N organic compounds in a new type of aqueous proton battery.The main research contents and results are as follows:（1）A full aqueous proton battery is assembled with polycarbonyl small molecule 5,7,12,14-pentacenetetralone（PT）as the anode electrode and graphite felt（GF）pre-deposited with Mn O₂ as the cathode electrode.Since the anode electrode material of the full battery is ketones,the specific capacity of the full battery is relatively high:124 m A h g^-1(at the current density of 0.3 A g^-1).The full battery shows a capacity of 104 m A h g^-1 at 1 A g^-1 and deliver capacity retention（48%）after2000 cycles.The ultraviolet and visible spectrophotometry（UV-Vis）test results prove that the dissolution of small organic molecules in the electrolyte is the main cause of poor battery cycle stability.Therefore,small organic molecules still need to be improved.（2）In order to decrease the dissolution of small organic molecules in the electrolyte,polyimide（PI）based on 1,4,5,8-naphthalenetetracarboxylic anhydride（NTCDA）and different diamines（ethylenediamine/urea）is synthesized through polycondensation.The productions are named as NTE and NTU,respectively.The electrochemical performance of monomer（NTCDA）and two polymers（NTE and NTU）are tested.The experimental results prove that because introduced additional active sites of urea and increased conjugated system,NTU has the excellent electrochemical performance.A full battery is constructed with NTU as the anode electrode and GF with pre-deposited Mn O₂ as the anode electrode.At a current density of 5 A g^-1,the specific capacity of the full battery can reach 82 m A h g^-1 after 120 cycles of activation,and the capacity retention rate of the full battery is still 67.9%after 5000 cycles.The results of the UV-vis test prove that the increased molecular weight and enlarged conjugated structure after polymerization can significantly alleviate the dissolution problem of organic electrode materials.However,the active site of conjugated carbonyl group has a low utilization in the actual reaction process,resulting in low specific capacity,which is still an urgent problem to be solved.（3）Due to the steric hindrance of the above materials,the utilization of active sites still needs to be improved.We use diquinoxalino[2,3-a:2’,3’-c]phenazine（HATN）as the anode electrode of aqueous proton battery.HATN has a conjugated planar structure to avoid steric hindrance,so the utilization of active sites is relatively high.Thanks to the occurrence of multiple electron transfer reactions,the HATN electrode show a high specific capacity of 304 m A h g^-1(theoretical specific capacity of 419 m A h g^-1),which is significantly higher than the utilization of the active sites of above organic compound electrode materials.In addition,HATN has strongπ-πintermolecular interaction,hence it is easy to assemble to form a stable crystal structure,which is conducive to rate capacity.Under the current density of 5 A g^-1,the specific capacity of the full battery can deliver250 m A h g^-1,and the capacity retention rate is 65.2%after 3300 cycles.Experiments have proved that HATN is a high specific capacity and stable cycle anode electrode material for aqueous proton batteries,and has broad application prospects.