Preparation And Lithium Storage Properties Of Flexible Composites Based On Electrodeposition Silicon

Flexible electronic products are one of the most promising development directions of electronic products.However,traditional battery often cannot withstand bending,folding and other operations,which severely limits the development of flexible electronic products.In this thesis,flexible three-dimensional silicon/carbon nanotube paper composite anode materials?Si/CNTs?were fabricated by galvanostatic electrodeposition method,and the characteristics of the composite electrode,such as its morphology,composition and mechanical properties,as well as the lithium storage performance of the lithium ion battery anode were studied.In addition,the charging and discharging behaviors of the flexible composite anode were explored.Furthermore,flexible half-cell were assembled.The main results of this thesis are listed as follows:?1?Using flexible three-dimensional carbon nanotube paper as a conductive substrate,the flexible Si/CNTs composite anode materials were prepared by a low-cost galvanostatic electrodeposition method to obtain an ultra-thin,light-weight,free-binder,and free-standing flexible composite anode.The results showed that the composite electrode maintained the porous structure of the three-dimensional carbon nanotubes,and the silicon deposit adhered firmly to the wall of the CNT;And the mechanical properties test showed that the Si/CNTs electrode had good flexibility and can repeatedly bent and twisted without being destroyed.?2?The above-mentioned flexible composite material was assembled into coin cell and tested for electrochemical performance.The test results showed that the electrodeposited silicon was the main active material.And regulating the quality of the electrodeposited silicon layer can effectively increase the volumetric specific capacity of the composite electrode.And the volumetric specific capacity of the electrode with a Si mass loading of 2.3 mg cm^-2 was 1925 mAh cm^-3 at 200 mA g^-1,which is higher than the silicon-based flexible electrode reported in most of the current literatures.However,the rate performance of the composite electrode was reduced with the increase of the volumetric capacity.?3?The use of direct contact?similar to short-circuit contact?pre-lithiation effectively solved the problem of low initial coulombic efficiencies of the Si/CNTs electrodes.?4?Using polydimethylsiloxane as the flexible packaging material,a flexible half-cell of Si/CNTs electrode was prepared.The flexible half-cell has a good flexibility,high voltage up to 2V or more.The cell can be discharged,and can light a red LED with a rated voltage of 1.8V.In summary,the flexible Si/CNTs composite anode material exhibited good flexibility and excellent electrochemical performance,and was expected to be used as an anode material for a flexible lithium-ion battery.This thesis can provide some guidance and reference for the research of ultra-thin flexible silicon-based anode.