Research On Crystallized Silicon Solar Cell Recycling Technology

By comparing the removal rates of the mixed acid of hydrochloric acid,nitric acid,nitric acid and hydrofluoric acid at different concentrations when the corresponding coating is removed,a macro leaching rate curve is made,and the recycling and recycling of the waste solar cells are obtained.Etching technology and technical parameters,that is,at room temperature with a volume fraction of 20%HCl solution,acid etching 30min remove the surface of the aluminum coating;room temperature with a volume fraction of 35%HNO₃solution,etching 70min remove the surface of the silver grid;The mixed acid composed of40%by volume of nitric acid and 6%of HF at room temperature was used to remove the silicon nitride coating and polish the crystalline silicon for 75 minutes.Samples were prepared for the important reaction time points in the reaction process,and microscopic analysis was performed by SEM and EDS to further confirm the true state of the macro leach rate curve.Because the recycling of solar cells needs to undergo a high temperature of 450?.to separate the frame and the cell,the solar cells obtained in practical applications must undergo a high temperature process.The experiment adopts the method of step-by-step chemical etching after high-temperature treatment and non-treatment of solar cells to compare the technical parameters of the recycling of the waste crystalline silicon solar cells and analyze the influence of the solar cells after high-temperature treatment.The experimental results show that the aluminum layer and the conductive silver paste on the solar cell after high temperature treatment are more easily removed,and the crystalline silicon doped layer becomes easier to activate and remove more easily.After the aluminum layer is treated with high temperature of 450?for half an hour,obvious oxidation phenomenon occurs,resulting in loose structure and easier reaction.The end point of the reaction is advanced to 20 minutes;most of the conductive silver paste in the cell sheet after high temperature treatment is oxidized,so it is easier to remove except.The reaction time at this stage was shortened by 40min;the time required for the removal of the pn junction of the solar cell after the high temperature treatment in the anti-reflection layer was shortened by 15 min,and due to the high temperature treatment,the crystalline silicon doping layer became more Easy to activate,easier to remove.The high temperature processed solar cells will lose more silicon content during the final stage of processing.This technical study considers the application in the actual industrial technology,adopts the stirring method to detect the difference of the experimental technical parameters in the dynamic process,and adopts the way of using the treatment liquid circulation to detect the circulation state,and the aluminum layer peeling process.At room temperature,at a solid-liquid ratio of 1:30,at 300 r/min,the reaction ended 5 minutes earlier than the static process,and the second cycle reaction ended 5 minutes later than the static process.The third cycle reaction ended 40 minutes later than the static process.As the conductive silver paste is more easily detached during the stirring process,the experimental results show that the concentration of nitric acid does not decrease significantly during the three cycles,and the reaction end point is 6 min earlier than the end time of the leaching reaction in the static state.There is almost no silver content in the agitated and removed residue,and it can be confirmed that almost all the silver is recovered during the silver recovery process.The recovery rate reached 99.58%.In the three cycles,the concentration of mixed acid in the treatment liquid for the removal of the anti-reflective layer is basically unchanged,and the experimental results show that the second phase of the reaction in the stirring process is shortened,and the second phase reaction of the static process is the reaction of the anti-reflection layer removal process.The time was shortened by 23 minutes and the polishing process time was shortened by 15 minutes.The total process end time was 22 min,and the recovery rate of crystalline silicon reached 71.18%.