Carbonization Of Acetate Fiber Under High Pressure And Its Application In Lithium Ion Battery

Based on the diversity of structures and the wide range of sources,pyrolytic carbon is considered as one of the ideal materials to replace the existing cathode of lithium ion batteries.Therefore,in order to improve its lithium storage capacity,various precursor and preparation technologies have been used to extensively study the carbonization behavior of pyrolytic carbon at different temperatures and pressures,such as crystallinity,chemical composition and microstructure,and many groundbreaking achievements have been obtained.However,we found that the current carbonization research under pressure,such as the self-boost method and the hydrothermal method,all have a thermodynamic one-way behavior,namely temperature control pressure,and lack of a study on carbonization behavior under the free and controllable state of three thermodynamic dimensions.Based on this,if the carbonization behavior of materials can be explored under the controllable conditions of pressure and temperature,it will be possible to fill the gap of relevant research under this system.In fact,as a pressure and temperature control equipment--Chinese six-sided top press,in China has half a century of use history.However,the modification equipment is mainly used in the field of superhard material synthesis,and its use as a means of carbonization research under the control of temperature and pressure has not been reported.In addition,for the precursor,we chose the cigarette waste containing acetate fiber,tobacco and paper.Our aim is: through this research,cigarette waste containing toxic and harmful substances can be converted into cathode materials for lithium ion batteries to realize its value-added services.In this paper,the thermodynamic behavior of three materials at different temperatures and pressures was studied by using the isostatic pressure pyrolysis technology.On this basis,the metal oxide was compounded with acetate fiber and the pyrolysis carbonization was studied under isostatic pressure.In addition,the pyrolytic carbon and its composites obtained under different conditions were used as the cathode of lithium ion battery for relevant tests.The results are as follows:（1）The effects of different temperature and pressure systems on the carbonization behavior of acetate fibers and the morphology and structure of pyrolytic carbon were studied.It is found that the increase of temperature and pressure helps to improve the graphitization degree of pyrolytic carbon and has a great influence on the morphology of pyrolytic carbon.In addition,the charge-discharge performance,multiplier performance,cycling performance,impedance and other electrochemical properties of these pyrolytic carbon as the anode material of lithium ion battery were studied.（2）To explore the carbonation effects of temperature and pressure on tobacco paper and tobacco.Firstly,under constant pressure,temperature rise contributes to theimprovement of graphitization degree of cigarette paper and tobacco,and cigarette paper is easier to graphitization than tobacco.Secondly,at constant temperature,the increase of pressure is conducive to the increase of carbonization degree.On this basis,the electrochemical test results of pyrolytic carbon at different temperatures and pressures were analyzed in detail.（3）In order to further improve the application of pyrolytic carbon in anode materials,carbonization of Co O（Sn O₂）/C composites was studied under high pressure.The results show that the disordered degree of pyrolytic carbon increases with the increase of metal oxide content.Co O（Sn O₂）/C with different mass fractions showed different morphologies and structures.Co O/C was easy to form a three-dimensional flake flower structure,while Sn O₂/C was easy to form a reticular porous structure.In addition,the electrochemical properties and lithium storage mechanism of Co O（Sn O₂）/C composites were investigated.