Preparation And Electrochemical Performance Study Of Graphene Based Lithium/Organic Battery Electrode Materials

Compared with traditional lithium-ion battery, lithium/organic(Li/O) battery as a new type of secondary battery, has high theroretical specific capacity, high specific energy, environment friendly and low-cost, traditional inorganic materials couldn’t meet the needs of social development, but organic materials have advantages over structural diversity and the machinability, thus Li/O battery is promising in wearable electronic equipments and new-type energy vehicles. However, because most of the organic matter is non-conductive insulator and during the progress of charge and discharge cycles the reaction make a lot of byproducts, Organic lithium salt dissolve easily In the organic electrolyte Cause a loss of active substances and the problems limited research progress and in the actual application of the Li/O battery.This paper on the basis of the study of the electrochemical performance of Li/O battery come to some significant causes the rapid decay of the Li/O battery electrochemical performance. And aimed at the essential problems to explore the way to improve its performance and obtained the ideal results. Experiment selected four kinds of organic(SAD, NAD, NTCDA and PTCDA) acid anhydride materials as the active material of lithium battery. Based on the electrochemical cycle test, cyclic voltammograms test, scanning electron microscope(SEM), transmission electron microscopy(TEM), infrared spectrum FT- IR testing and analysis the material before and after charge-discharge, this experiment come to some conclusions such as, in the lithium battery organic active substances easily dissolved in the electrolyte and causes the loss of the anode materials, The smallest molecular weight organic matter succinic anhydride(SAD) are more likely to happen to dissolve, from the first cycle discharge specific capacity of 217 mAh/g(80% of the theoretical capacity) after the second cycle the value attenuation to 56 mAh/g, after five cycles the discharge specific capacity decay rapidly and stability in the 23 mAh/g. And the 3,4,9,10-Perylenetetracarboxylic dianhydride(PTCDA) which own the biggest molecular weight after 100 cycles the discharge specific capacity from the initial 130.8 mAh/g(95% of the theoretical capacity) slow down to 86 mAh/g, on the basis of SEM the smaller the molecular weight of Li/O batteries the more sediment on Li-foil, in constant current charge and discharge process of Li/O organic materials dissolved in the electrolyte and through the battery membrane deposit on the Li-foil, greatly influence on the efficiency of lithium.Based on these conclusions, this paper designs a kind of organic- graphene composite material. The good electrical conductivity of chemical modification of graphene piece have been proved during the test. Its unique layered structure offers organic the electron transport corridor, There are abundant crosslinked hole structure in the layered and effectively prevent the organic matter and its reaction products organic lithium salt dissolution and direct contact with the electrolyte. The layered structure of graphene sheet has the larger specific surface area and provide great storage space for organic matter particles, increase the organic contact with lithium ions and beneficial to the reaction of Li+ de/insert. For this experiment effectively improve the electrochemical properties of the organic matter. Take PTCDA for instance, after 100 cycles the discharge specific capacity of PTCDA/Super-P/PVDF electrode from 130 mAh/g attenuation to 86 mAh/g and still attenuation. But the PTCDA-CCG electrode after 200 cycles can still retain stable discharge specific capacity of 95 mAh/g. Concluded by the analysis that the organic composite with Graphene not only improve the discharge specific capacity but also get a good cycle stability.