Preparation Of Conductive Polymer Modified Titanium-based Compounds Composites And Research On The Electrochemical Behavior

Electrical energy storage is critical to the efficient use of renewable energy.Vehicle electrification also requires advanced energy storage technology to provide high energy and high power density.Lithium-ion batteries provide the highest energy density systems in known batteries and are considered to be the most feasible way to solve these application problems in the near future.Although there are many problems such as cost,safety and energy in the successful market of portable electronic products,this has hindered the practical application of large-size lithium-ion batteries.Therefore,the development of higher capacity,higher performance alternative anodes is the way needed for large-scale application of lithium ion technology.Sulfur is one of the most abundant elements on Earth,with a theoretical specific capacity of up to 1675 mAh/g,making it a potential cathode material for high-capacity lithium-sulfur batteries.So far,lithium-sulfur batteries are still in the laboratory research and development stage,the available energy density is still far below the theoretical value,and the sulfur materials of the lithium-sulfur battery cathode material itself has low electrical conductivity,volume changes during charge and discharge,and other issues,making the electrochemical The performance was unsatisfactory,limiting its large-scale industrial production.In response to these problems,we present a convenient method to achieve favorable surface modification by depositing PEDOT nanoparticles on Ti-based metal oxides by in-situ oxidative polymerization.Compared to Ti-based metal oxides/sulfur and PEDOT/sulfur,ternary PEDOT/Ti-based metal oxides/sulfur exhibit better cycle stability and cycle efficiency.The analysis of the excellent electrochemical PEDOT/Ti-based metal oxide/sulfur cathode properties is attributed to the strong chemical attractive adsorption of polysulfides consisting of Ti-based metal oxide nanoparticles and highly conductive PEDOT.The PEDOT/TiO₂nanocomposites?NCs?we prepared here provide a two-in-one method to improve the electrochemical performance of the sulfur-based cathodes and have potential for high-performance lithium batteries.In this paper,based on these problems in lithium-sulfur batteries,we have begun research on the host material of elemental sulfur in cathode materials.We explored and tried PEDOT/S,TiO₂/S,Ti₄O₇/S,PEDOT/TiO₂/S,PEDOT/Ti₄O₇/S electrode materials respectively,aiming at finding a very suitable cathode material to improve the electrical conductivity of sulfur cathode and suppress Polysulfide migration.The PEDOT/TiO₂ nanomaterial is used as a carrier of sulfur to further modify the positive electrode of the lithium-sulfur battery and improve the performance of the lithium-sulfur battery.However,since TiO₂ is not conductive,we suspect that this insulation may limit the performance of lithium-sulfur batteries to a certain extent.After consulting the literature and learning from the relevant experience of the research group,we have developed conductive Ti₄O₇ nanorods and further improved the performance of lithium-sulfur batteries.PEDOT compounded to obtain the composite material PEDOT/Ti₄O₇,which has been applied to the cathode material to achieve the desired effect.The main research content is as follows:?1?PEDOT/TiO₂ nano-particles were prepared by in-situ oxidative polymerization,and then PEDOT/TiO₂/S composite cathode materials were prepared by thermal fusion at 155°C with elemental sulfur.The XPS experiment verified the existence of chemical bonding between titanium dioxide and polysulfide,reducing the polysulfide shuttle effect.Through CV and impedance test analysis,PEDOT can improve the conductivity of the cathode material,thereby reducing the battery charge transfer resistance,is conducive to promoting the electrochemical reaction and improve the electrochemical performance of lithium-sulfur batteries.At a current density of 1 C,500 cycles of charge and discharge cycles,a reversible specific capacity of 532.1 mAh/g remains.?2?In this paper,Ti₄O₇ nanoparticles were prepared by the method of hydrogen reduction,and then PEDOT/Ti₄O₇ composites were prepared by in-situ oxidation polymerization and sublimation of sulfur,followed by the same method of hot melting PEDOT/Ti₄O₇/S composite cathode material?Compared with PEDOT/S and pure Ti₄O₇/S electrodes,PEDOT/Ti₄O₇/S composite cathode materials have been greatly improved in cycle and rate performance.At a current density of 1 C,500 cycles of charge and discharge were performed,and a reversible specific capacity of 566.1mAh/g remained.At a high rate of discharge of 4 C,the discharge specific capacity reached 416.8 mAh/g.