Experimental Study On The Deposition Characteristics Of Cold Sprayed Substrate By Silicon Powder And Copper-silicon Mixed Powder

Silicon material is expected to be a new type of lithium ion battery anode material for graphite replacement because of its highest theoretical specific capacity(4200mAh / g)and high lithium intercalation potential(0.2V).However,the silicon anode will appear dramatic volume effect(300%)in the charge and discharge process,will cause the silicon particles crushing and pulverization,leading to the silicon cathode lost electrical contact with the collector,resulting in the battery will loss of activity.The silicon material have low conductivity,and its rate performance is poor,which will seriously affect the applications of silicon material as a lithium-ion battery anode material.Improve the capacity of lithium-ion battery of the charge retention capability of it has become a key issues we need to breakthrough in the research of lithium-ion battery.If apply new binder,anode materials can also improve the battery cycle performance,but under the consideration of large-scale application,the manufacture of silicon-based composite material with nanostructures has the greatest potential for development.At present,most of the laboratory research methods of preparing silicon-based composite materials are expensive,complex.therefore,the development of a simple,low-cost,uniform method of combining nanostructured silicon-based materials with collectors is the focus of the development of new silicon-based electrodes.The cold spray method is such a simple,economical method for the preparation of silicon-based negative batteries.In 2007,Japanese scholars have tried to use low-pressure cold spray method to prepare silicon-based anode material,showing a good cycle performance.But lack of research on the mechanism of coating formation during the preparation process,this paper mainly though the experimental method to explore the deposition characteristics in the process of cold spray preparation of silicon-based anode material,it can provide a theoretical reference for the preparation of lithium-ion silicon-based negative battery when use cold spray method.At first use the self-made high-pressure cold spraying equipment to sprayed silicon or copper-silicon mixed powder on the substrate under different gas parameters,spray pass(spray several passes means repeated spray several times),particle size,substrate material,then through the post-processing to obtain coating section,the surface and cross-sectional features of the coatings were observed by scanning electron microscopy,the coating structure was analyzed by energy spectrum analyzer and X-ray diffractometer,and the main factors affecting the structure of the coating were put forward.The results show that the silicon particles are broken when sprayed and the copper of the substrate is eroded or squeezed to the surface,then subsequent silicon particles compress the extruded copper to cover the silicon particles.When the particle size of the silicon particles is appropriate,a coating layer having a deeper depth of silicon embedding can be realized by increasing the particle size of the silicon particles.When there are copper powder involved in the sprayed,the temperature is too high will make the coating oxidation serious.The silicon distribution on both sides of the bottom will be significantly higher when the point is continuously sprayed.