Preparation method of battery piece with composite conducting layer

Abstract

The invention provides a preparation method of a battery piece with a composite conducting layer, and the method comprises the following steps: carrying out the graphical grooving of a P surface and an N surface of a battery piece body, forming an electrode opening region, and exposing a P electrode and an N electrode; preparing a passivation tunneling layer on the P surface of the cell body; preparing an ohmic contact layer in the electrode opening area of the P surface and / or the N surface of the cell body; and preparing a binding layer, an electrode layer and a protective layer in the electrode opening area in sequence. The solar cell has the advantages that the ohmic contact layer and the passivation tunneling layer form the composite conducting layer, the passivation tunneling layer is continuously and evenly distributed on the P face of the cell piece, the thickness of the passivation tunneling layer is in the nanometer level, the defect state density of the surface of the cell piece is reduced, the recombination rate of carriers on the surface is reduced, and the performance of the solar cell is improved. The open-circuit voltage of the primary battery piece is not reduced; meanwhile, work function matching can be carried out, recombination of photo-induced electrons and holes can be effectively inhibited, the photo-hole migration efficiency is integrally prolonged, and the contact resistance is synchronously reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a method for preparing a solar cell having a composite conductive layer. Background Art

[0002] With the development of the photovoltaic industry, reducing production costs has become a key goal. Currently, using electroplated copper to replace expensive conductive silver paste in the production of metal grid lines has achieved significant results. The cost difference between one gram of silver and one gram of copper is over 100 times, making the trend towards silver-free production inevitable.

[0003] Among the various photovoltaic cell types produced, N-type TOPCon cells are the most mass-produced. The key to their manufacturing process is the formation of an anti-reflection layer—a tunneling oxide layer of SiO2 (1nm-3nm)—on the N-side, and an anti-reflection layer—an aluminum oxide layer of Al2O3 (5nm-10nm)—on the P-side. This provides excellent passivation for the TOPCon cell. Finally, an anti-reflection layer (such as SiNx) and conductive grid lines are printed on both sides of the cell to create an N-type TOPCon cell.

[0004] However, when introducing the copper electroplating process, the anti-reflection layer on both sides of the cell must be partially and continuously or discontinuously removed using a laser. After exposing the P / N poles, an ohmic contact layer is then applied via electroplating or chemical deposition to facilitate the subsequent electroplating process. However, this not only destroys the anti-reflection layer function of the original cell (increasing recombination and reducing the cell's Voc), but also, the ohmic contact layer prepared using a micron-scale process (electroplating / chemical plating) often cannot fully contact and react with the silicon surface due to the cell's surface topography (such as velvet). This ultimately leads to uneven deposition and the inability to form a continuous and evenly distributed ohmic contact layer. A good ohmic contact layer not only allows current to be evenly transmitted from the cell's doped layer to the metal electrode, but also avoids local current failure or even heat concentration caused by poor contact, which not only affects current collection efficiency but also affects the reliability of the cell and module. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method for preparing a battery cell with a composite conductive layer to solve the above or other problems existing in the prior art.

[0006] To solve the above technical problems, the present invention adopts a technical solution: a method for preparing a battery cell with a composite conductive layer, comprising the following steps:

[0007] The P-side and N-side of the battery cell body are respectively patterned to form electrode opening areas, exposing the P electrode and N electrode;

[0008] Prepare a passivation tunneling layer on the P surface of the battery cell body;

[0009] Prepare ohmic contact layers in the electrode opening areas on the P-side and N-side of the battery cell body;

[0010] A bonding layer, an electrode layer and a protective layer are sequentially prepared in the electrode opening area.

[0011] Furthermore, the thickness of the passivation tunneling layer is 1-5 nm.

[0012] In some embodiments, the thickness of the passivation tunneling layer is 1-5 nm.

[0013] Furthermore, a passivation tunneling layer is prepared by heat treatment. The passivation tunneling layer is formed in the electrode opening area of the P surface of the battery cell body. The heat treatment temperature is 550-900° C. and the heat treatment time is 5-120 seconds.

[0014] Furthermore, the passivation tunneling layer is made of silicon oxide.

[0015] Furthermore, the steps of preparing an ohmic contact layer in the electrode opening regions on the P-side and N-side of the cell body include:

[0016] Depositing a first metal on the N-side of the heat-treated battery cell body to form a first metal layer;

[0017] After the first metal is deposited, a second metal is deposited on the P surface of the heat-treated battery cell body to form a second metal layer;

[0018] After the second metal is deposited, an annealing treatment is performed to prepare an ohmic contact layer.

[0019] Furthermore, the first metal is deposited by electroplating or light-induced electroplating, and the thickness of the first metal layer is 500-1000 nm.

[0020] Furthermore, the second metal is deposited by magnetron sputtering or evaporation, and the thickness of the second metal layer is 5-200 nm.

[0021] Furthermore, the first metal layer and the second metal layer are made of different materials. The materials of the first metal layer and the second metal layer include silver, cobalt, tungsten, nickel, vanadium, gold, titanium, aluminum or alloys.

[0022] Furthermore, when annealing is performed after the second metal is deposited, the annealing temperature is 200-650° C. and the annealing time is 30-300 seconds.

[0023] Furthermore, the annealed cell body is etched to remove the first metal deposited in areas other than the electrode opening area on the N side of the cell body and the second metal deposited in areas other than the electrode opening area on the P side of the cell body.

[0024] In some feasible embodiments, the material of the passivation tunneling layer is silicon oxide, aluminum oxide, nickel oxide or titanium oxide.

[0025] Furthermore, a chemical vapor deposition method is used to control the flow rate of the reaction source, the flow rate of the oxygen source, the reaction temperature and the reaction time to prepare a passivation tunneling layer. The reaction source includes a silicon source, an aluminum source, a nickel source or a titanium source, and the oxygen source includes oxygen.

[0026] Furthermore, the silicon source includes SiH4, the flow rate of the silicon source is 5-70 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-800°C, and the reaction time is 30-600s;

[0027] The aluminum source includes trimethylaluminum, the flow rate of the aluminum source is 10-50 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-400°C, and the reaction time is 30-600s;

[0028] The nickel source includes Ni(CO)4, the flow rate of the nickel source is 10-50 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-600°C, and the reaction time is 30-600s;

[0029] The titanium source includes TiCl4, the flow rate of the titanium source is 5-70 sccm, the flow rate of the oxygen source is 400-800 sccm, the reaction temperature is 600-1000°C, and the reaction time is 30-600s.

[0030] Furthermore, a plasma-enhanced chemical vapor deposition method is used to control the flow rate, reaction temperature, reaction time and reaction power of the reaction gas to prepare a passivation tunneling layer. The reaction gas includes a mixed gas of a silicon source and a nitrogen oxide compound or a mixed gas of an aluminum source and an oxygen source or a mixed gas of a nickel source and an oxygen source or a mixed gas of a titanium source and an oxygen source.

[0031] Furthermore, the mixed gas of the silicon source and the nitrogen oxide compound includes SiH4 and N2O mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the silicon source and the nitrogen oxide compound is 10-100 sccm, the reaction power is 100-300 W, the reaction temperature is 200-400° C., and the reaction time is 30-600 s;

[0032] The mixed gas of the aluminum source and the oxygen source includes trimethylaluminum and O2 mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the aluminum source and the oxygen source is 10-100 sccm, the reaction power is 100-300 W, the reaction temperature is 200-500 ° C, and the reaction time is 30-600 s;

[0033] The mixed gas of the nickel source and the oxygen source includes Ni(CO)4 and O2 mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the nickel source and the oxygen source is 10-100 sccm, the reaction power is 100-300 W, the reaction temperature is 200-500° C., and the reaction time is 30-600 s;

[0034] The mixed gas of the titanium source and the oxygen source includes TiCl4 and O2 mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the titanium source and the oxygen source is 10-100 sccm, the reaction power is 100-300W, the reaction temperature is 300-600°C, and the reaction time is 30-600s.

[0035] Furthermore, metal is deposited on the P and N sides of the cell body using PVD, and annealing is performed after deposition to prepare an ohmic contact layer. The deposited metals on the P and N sides of the cell body are different, and the thickness of the ohmic contact layer is 1-100nm.

[0036] Furthermore, the thickness of the deposited metal is 5-200 nm, and the deposited metal material includes silver, cobalt, tungsten, nickel, vanadium, gold, titanium, aluminum or alloy

[0037] Furthermore, in the annealing step after deposition, the annealing temperature is 250-650° C. and the annealing time is 30-180 seconds.

[0038] Furthermore, the annealed cell body is etched to remove the deposited metal in other areas of the P-side and N-side of the cell body except the electrode opening area.

[0039] Furthermore, the annealed cell body is etched with an etching solution at a temperature of 20-60° C. for a time of 1-30 minutes.

[0040] Furthermore, the etching solution includes hydrochloric acid, formic acid and sodium hydroxide, the mass percentage of hydrochloric acid in the etching solution is 1%-15%, the mass percentage of formic acid in the etching solution is 3%-20%, and the mass percentage of sodium hydroxide in the etching solution is 3%-15%.

[0041] Furthermore, the bonding layer, electrode layer and protective layer are all prepared by wet electroplating deposition process, wherein:

[0042] The material of the bonding layer includes nickel, tungsten, silver or titanium, and the thickness of the bonding layer is 0.1-3um;

[0043] The material of the electrode layer includes copper, and the thickness of the electrode layer is 5-50um;

[0044] The material of the protective layer includes nickel, tin or silver, and the thickness of the protective layer is 0.1-3um.

[0045] Furthermore, before preparing the passivation tunneling layer on the P surface of the cell, the cell body after the grooves are sequentially subjected to thermal repair and acid treatment.

[0046] Due to the adoption of the above technical solution, when preparing the cell with a composite conductive layer, a passivation tunneling layer of a certain thickness is prepared on the P-side of the laser-grooved cell body. After the passivation tunneling layer is prepared, an ohmic contact layer is prepared on the P-side and N-side of the cell body. The ohmic contact layer and the passivation tunneling layer constitute a composite conductive layer. The passivation tunneling layer can be continuously and evenly distributed on the P-side of the cell, or the passivation tunneling layer can be arranged at the groove of the P-side of the cell, and the thickness of the passivation tunneling layer is nanometer-level, which reduces the defect state density on the cell surface, thereby reducing the carrier recombination rate on the surface. Therefore, the decrease in the open-circuit voltage (Voc) of the solar cell caused by the previous removal of the local anti-reflection layer can be avoided, so that the open-circuit voltage of the original cell is not reduced. At the same time, the provision of the passivation tunneling layer can achieve work function matching, which can effectively suppress the recombination of photogenerated electrons and holes, overall extend the photo-hole migration efficiency and simultaneously reduce the contact resistance.

[0047] The setting of the ohmic contact layer, the thickness of the ohmic contact layer is at the nanometer level, so that the electroplating process of the thick electrode structure can achieve the maximum overall conversion efficiency improvement of the battery cell. Through the vacuum deposition process or the electroplating process combined with the annealing process, a uniform and well-contacted ohmic contact layer can be obtained, thereby achieving the purpose of reducing the contact resistance of the battery cell, and combined with the subsequent electroplating process of the electrode structure, the conversion efficiency of the battery cell is improved and the production cost of the battery cell is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 1 is a schematic structural diagram of a battery cell body after slotting according to the first embodiment of the present invention;

[0049] Figure 2 This is a schematic structural diagram of preparing a passivation tunneling layer on the P surface of a battery cell body according to the first embodiment of the present invention;

[0050] Figure 3 Schematic diagram of the structure of preparing ohmic contact layers on the P-side and N-side of the battery cell body according to the first embodiment of the present invention;

[0051] Figure 42. It is a schematic structural diagram of a battery cell in which bonding layers are prepared on the P-side and N-side of the battery cell body according to the first embodiment of the present invention;

[0052] Figure 5 2. It is a schematic structural diagram of a battery cell in which electrode layers are prepared on the P-side and N-side of the battery cell body according to the first embodiment of the present invention;

[0053] Figure 6 1 is a schematic structural diagram of a battery cell after protective layers are formed on the P-side and N-side of the battery cell body according to the first embodiment of the present invention;

[0054] Figure 7 Schematic diagram of the structure of preparing a passivation tunneling layer on the P surface of the battery cell body according to the second embodiment of the present invention;

[0055] Figure 8 Schematic diagram of the structure of preparing ohmic contact layers on the P-side and N-side of the battery cell body according to the second embodiment of the present invention;

[0056] Figure 9 2 is a schematic structural diagram of a battery cell in which bonding layers are prepared on the P-side and N-side of the battery cell body according to the second embodiment of the present invention;

[0057] Figure 10 2 is a schematic structural diagram of a battery cell in which electrode layers are prepared on the P-side and N-side of the battery cell body according to the second embodiment of the present invention;

[0058] Figure 11 It is a schematic structural diagram of a battery cell after protective layers are prepared on the P-side and N-side of the battery cell body according to the second embodiment of the present invention.

[0059] In the picture:

[0060] 1. Liner 2. P electrode 3. Aluminum oxide layer

[0061] 4. Anti-reflection layer 5. Silicon dioxide layer 6. N electrode

[0062] 7. Passivation tunneling layer 8. Ohmic contact layer 9. Bonding layer

[0063] 10. Electrode layer 11. Protective layer DETAILED DESCRIPTION

[0064] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0065] Figure 1A structural schematic diagram of an embodiment of the present invention is shown. This embodiment relates to a method for preparing a battery cell with a composite conductive layer, in which a passivation tunneling layer is prepared on the P-side of the battery cell body after slotting to reduce the defect state density on the battery cell surface and the carrier recombination rate on the surface. Then, an ohmic contact layer is prepared on the passivation tunneling layer at the P-side slotting of the battery cell body and on the N-side slotting, respectively, and a metal electrode structure is prepared on the ohmic contact layer to reduce contact resistance, improve the conversion efficiency of the battery cell, and reduce the production cost of the battery cell.

[0066] Example 1

[0067] A method for preparing a battery cell with a composite conductive layer comprises the following steps:

[0068] The P side and N side of the cell body are patterned and grooved to form electrode opening areas, exposing the P electrode 2 and the N electrode 6, so as to facilitate the subsequent setting of the passivation tunneling layer 7 and the ohmic contact layer 8. Figure 1 As shown, according to the design requirements of the battery cell structure, graphic grooves are performed at the designed positions of the P and N sides of the battery cell to provide a basis for the subsequent preparation of the passivation tunneling layer 7, the ohmic contact layer 8 and the metal electrode. When the battery cell body is graphic grooved, the P side of the battery cell body is graphic grooved, the passivation tunneling layer 7 and the ohmic contact layer 8 are prepared on the P side of the battery cell body, the N side of the battery cell body is graphic grooved, and the ohmic contact layer 8 is prepared on the N side of the battery cell body. The setting position of the graphic groove is selected and set according to the type of the battery cell body and the actual structural design requirements of the battery cell, and no specific requirements are made here.

[0069] The above-mentioned cell body is a cell on which the anti-reflection layer 4 is prepared. For example, the cell body can be a TOPCon cell prepared with an anti-reflection layer 4. The cell body includes a liner 1, and a P electrode 2, an aluminum oxide layer 3 and an anti-reflection layer 4 are arranged in sequence on the P surface of the liner 1, and a silicon dioxide layer 5, an N electrode 6 and an anti-reflection layer 4 are arranged in sequence on the N surface of the liner 1.

[0070] When patterning the cell body, laser grooves are performed on the cell body where metal electrodes are required. On the P side of the cell body, the aluminum oxide layer 3 and anti-reflection layer 4 are removed at the corresponding locations, exposing the P electrode 2 beneath the aluminum oxide layer 3 and anti-reflection layer 4. On the N side of the cell body, the anti-reflection layer 4 is removed at the corresponding locations, exposing the N electrode 6 beneath the anti-reflection layer 4, forming an electrode opening area. The subsequently prepared ohmic contact layer 8 is disposed in this electrode opening area so that the metal electrode forms effective contact with the semiconductor through the ohmic contact layer 8, facilitating the input and output of current. Here, the grooved area is the electrode opening area, and the area outside the grooved area is the non-electrode opening area.

[0071] After the laser grooving of the cell body is completed, thermal repair and acid treatment are sequentially performed to remove impurities on the cell body surface to facilitate the subsequent preparation of the passivation tunneling layer 7. When thermally repairing the cell after the grooving is completed, the cell is placed in a tunnel furnace and placed in an atmospheric atmosphere for heating and repair. The thermal repair temperature is 550-900°C and the thermal repair time is 5-120 seconds. By controlling the thermal repair temperature and time, an oxide layer is formed at the groove, so that the damage caused to the cell during the laser grooving can be removed through cleaning.

[0072] In some feasible embodiments, the temperature of the thermal repair can be 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, or any temperature value between 550-900℃. It can be selected and set according to actual needs, and no specific requirements are made here.

[0073] In some feasible embodiments, the time of the hot repair is 20s, 40s, 60s, 80s, 100s, 120s, or any other time value between 5-120s. The time value is selected and set according to actual needs, and no specific requirements are made here.

[0074] After the slotted battery cells are thermally repaired, they are acid-treated. At room temperature, the thermally repaired battery cells are cleaned with acid to remove the oxide layer and impurities on the surface of the battery cells. The acid is a hydrofluoric acid solution with a concentration of 0.5%-3%. The acid treatment time is 30-300s. By controlling the cleaning time of the acid solution, the oxide layer is removed and the impurities on the surface of the battery cells are removed at the same time.

[0075] like Figure 2 As shown, a passivation tunneling layer 7 is prepared on the P surface of the cell to play a tunneling role, reduce the defect state density on the surface of the cell, and reduce the recombination rate of carriers on the surface. The thickness of the passivation tunneling layer 7 is 1-5nm, which is a passivation tunneling layer 7 of nano-physical scale. It can avoid the result of the open circuit voltage of the solar cell being reduced due to the previous removal of the local anti-reflection layer 4, and achieve the open circuit voltage of the solar cell not being reduced; in the P-pole structure design of the N-type TOPCon cell, the P-pole of the P surface is used for the transfer and collection of holes, that is, the work function of the boron-doped silicon (p poly) is controlled in the range of 4.8ev-5.0ev, and the two materials with the lower work function aluminum oxide layer 3 (controlling its work function range of 4.0ev-4.5ev) are stacked. At this time, the holes will be transported from the high work function (p poly) migrates to the material with low work function (aluminum oxide layer 3), and the passivation tunneling layer 7 can effectively inhibit the recombination of photogenerated electrons and holes, overall prolong the efficiency of photohole migration, and reduce contact resistance.

[0076] In some feasible embodiments, the thickness of the above-mentioned passivation tunneling layer 7 can be 1nm, 2nm, 3nm, 4nm, 5nm, or any other thickness value between 1-5nm. The thickness of the passivation tunneling layer 7 is selected and set according to actual needs, and no specific requirements are made here.

[0077] The material of the above-mentioned passivation tunneling layer 7 is silicon oxide, aluminum oxide, nickel oxide or titanium oxide. The material of the passivation tunneling layer 7 is selected and set according to actual needs, and no specific requirements are made here.

[0078] The passivation tunneling layer 7 covers the P surface of the cell after the grooves are formed, and is located in the electrode opening area of the P surface of the cell body and the non-electrode opening area except the electrode opening area, and is a continuous thin film structure.

[0079] When preparing the passivation tunneling layer 7, a chemical vapor deposition (CVD) method can be used to deposit it in a chemical vapor deposition vacuum equipment, controlling the flow rate of the reaction source, the flow rate of the oxygen source, the reaction temperature and the reaction time to prepare the passivation tunneling layer 7. The above-mentioned reaction source includes a silicon source, an aluminum source, a nickel source or a titanium source, and the above-mentioned oxygen source includes oxygen.

[0080] Specifically, the silicon source includes SiH4, the flow rate of the silicon source is 5-70 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-800°C, and the reaction time is 30-600s.

[0081] In some feasible embodiments, the flow rate of the silicon source can be 10sccm, 20sccm, 30sccm, 40sccm, 50sccm, 60sccm, or any other flow rate value between 5-70sccm. The selection is made according to actual needs and no specific requirements are made here.

[0082] In some feasible embodiments, the flow rate of the oxygen source can be 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, or any other flow rate value between 50-500 sccm, which can be selected according to actual needs and no specific requirements are made here.

[0083] In some feasible embodiments, the reaction temperature can be 200°C, 400°C, 600°C, 800°C, or any other temperature value between 200-800°C. The temperature can be selected according to actual needs and no specific requirements are given here.

[0084] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0085] The aluminum source includes trimethylaluminum, the flow rate of the aluminum source is 10-50 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-400° C., and the reaction time is 30-600 s.

[0086] In some feasible embodiments, the flow rate of the aluminum source can be 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, or any other flow rate value between 10-50 sccm. The selection is made according to actual needs and no specific requirements are made here.

[0087] In some feasible embodiments, the flow rate of the oxygen source can be 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, or any other flow rate value between 50-500 sccm, which can be selected according to actual needs and no specific requirements are made here.

[0088] In some feasible embodiments, the reaction temperature can be 200°C, 250°C, 300°C, 350°C, 400°C, or any other temperature value between 200-400°C. The selection is based on actual needs and no specific requirements are made here.

[0089] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0090] The nickel source includes Ni(CO)4, the flow rate of the nickel source is 10-50 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-600°C, and the reaction time is 30-600s.

[0091] In some feasible embodiments, the flow rate of the nickel source can be 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, or any other flow rate value between 10-50 sccm. The selection is made according to actual needs and no specific requirements are made here.

[0092] In some feasible embodiments, the flow rate of the oxygen source can be 100 sccm, 200 sccm, 300 sccm, 400 sccm, 500 sccm, or any other flow rate value between 50-500 sccm, which can be selected according to actual needs and no specific requirements are made here.

[0093] In some feasible embodiments, the reaction temperature can be 200°C, 300°C, 400°C, 500°C, 600°C, or any other temperature value between 200-600°C. The selection is based on actual needs and no specific requirements are made here.

[0094] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0095] The titanium source includes TiCl4, the flow rate of the titanium source is 5-70 sccm, the flow rate of the oxygen source is 400-800 sccm, the reaction temperature is 600-1000°C, and the reaction time is 30-600s.

[0096] In some feasible embodiments, the flow rate of the titanium source can be 10 sccm, 30 sccm, 50 sccm, 70 sccm, or any other flow rate value between 5-70 sccm, which can be selected according to actual needs and no specific requirements are made here.

[0097] In some feasible embodiments, the flow rate of the oxygen source can be 400 sccm, 500 sccm, 600 sccm, 700 sccm, 800 sccm, or any other flow rate value between 400-800 sccm. The flow rate can be selected based on actual needs and no specific requirements are given here.

[0098] In some feasible embodiments, the reaction temperature can be 600°C, 700°C, 800°C, 900°C, 1000°C, or any other temperature value between 600-1000°C. The selection is made according to actual needs and no specific requirements are made here.

[0099] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0100] Alternatively, the above-mentioned passivation tunneling layer 7 can also be deposited by a plasma enhanced chemical vapor deposition (PECVD) method in a plasma enhanced chemical vapor deposition vacuum device, controlling the flow rate of the reaction gas, the reaction temperature, the reaction time and the reaction power to prepare the passivation tunneling layer 7, wherein the reaction gas includes a mixed gas of a silicon source and a nitrogen oxide or a mixed gas of an aluminum source and an oxygen source or a mixed gas of a nickel source and an oxygen source or a mixed gas of a titanium source and an oxygen source.

[0101] Specifically, the above-mentioned mixed gas of silicon source and nitrogen oxide includes SiH4 and N2O mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of silicon source and nitrogen oxide is 10-100sccm, the reaction power is 100-300W, the reaction temperature is 200-400℃, and the reaction time is 30-600s.

[0102] In some feasible embodiments, the flow rate of the mixed gas of silicon source and nitrogen oxide compound can be 20sccm, 40sccm, 60sccm, 80sccm, 100sccm, or any other flow rate value between 10-100sccm, which can be selected according to actual needs and no specific requirements are made here.

[0103] In some feasible embodiments, the reaction power can be any power value between 100-300W, such as 100W, 150W, 200W, 250W, 300W, etc., which can be selected according to actual needs and no specific requirements are made here.

[0104] In some feasible embodiments, the reaction temperature can be 200°C, 250°C, 300°C, 350°C, 400°C, or any other temperature value between 200-400°C. The selection is based on actual needs and no specific requirements are made here.

[0105] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0106] The mixed gas of the aluminum source and oxygen source includes trimethylaluminum and O2 mixed in a ratio of 1:1-1:30. The flow rate of the mixed gas of the aluminum source and oxygen source is 10-100 sccm, the reaction power is 100-300W, the reaction temperature is 200-500°C, and the reaction time is 30-600s.

[0107] In some feasible embodiments, the flow rate of the mixed gas of the aluminum source and the oxygen source can be 20sccm, 40sccm, 60sccm, 80sccm, 100sccm, or any other flow rate value between 10-100sccm. The selection is made according to actual needs and no specific requirements are made here.

[0108] In some feasible embodiments, the reaction power can be any power value between 100-300W, such as 100W, 150W, 200W, 250W, 300W, etc., which can be selected according to actual needs and no specific requirements are made here.

[0109] In some feasible embodiments, the reaction temperature can be 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, or any other temperature value between 200-500°C. The selection is based on actual needs and no specific requirements are made here.

[0110] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0111] The mixed gas of the nickel source and oxygen source includes Ni(CO)4 and O2 mixed in a ratio of 1:1-1:30. The flow rate of the mixed gas of the nickel source and oxygen source is 10-100sccm, the reaction power is 100-300W, the reaction temperature is 200-500℃, and the reaction time is 30-600s.

[0112] In some feasible embodiments, the flow rate of the mixed gas of the nickel source and the oxygen source can be 20sccm, 40sccm, 60sccm, 80sccm, 100sccm, or any other flow rate value between 10-100sccm. The selection is made according to actual needs and no specific requirements are made here.

[0113] In some feasible embodiments, the reaction power can be any power value between 100-300W, such as 100W, 150W, 200W, 250W, 300W, etc., which can be selected according to actual needs and no specific requirements are made here.

[0114] In some feasible embodiments, the reaction temperature can be 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, or any other temperature value between 200-500°C. The selection is based on actual needs and no specific requirements are made here.

[0115] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0116] The mixed gas of the titanium source and oxygen source includes TiCl4 and O2 mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the titanium source and oxygen source is 10-100 sccm, the reaction power is 100-300W, the reaction temperature is 300-600℃, and the reaction time is 30-600s.

[0117] In some feasible embodiments, the flow rate of the mixed gas of the titanium source and the oxygen source can be 20sccm, 40sccm, 60sccm, 80sccm, 100sccm, or any other flow rate value between 10-100sccm. The selection is made according to actual needs and no specific requirements are made here.

[0118] In some feasible embodiments, the reaction power can be any power value between 100-300W, such as 100W, 150W, 200W, 250W, 300W, etc., which can be selected according to actual needs and no specific requirements are made here.

[0119] In some feasible embodiments, the reaction temperature can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, or any other temperature value between 300-600°C. The selection is based on actual needs and no specific requirements are made here.

[0120] In some feasible embodiments, the reaction time can be 100s, 300s, 500s, or any other time value between 30-600s, and is selected according to actual needs. No specific requirements are made here.

[0121] like Figure 3 As shown, after the passivation tunneling layer 7 is prepared, an ohmic contact layer 8 is prepared in the electrode opening areas on the P and N sides of the cell body: metal is deposited on the P and N sides of the cell body using PVD, and annealing is performed after deposition to prepare the ohmic contact layer 8. When metal deposition is performed using PVD, a metal deposition layer is deposited on the P and N sides of the cell body respectively. When metal deposition is performed on the cell body, the cell body is placed in a vacuum deposition device for vacuum sputtering deposition, and metal deposition is performed on both the P and N sides of the cell body. In this case, metal deposition can be performed on one side of the cell body first, and then on the other side of the cell body, or metal deposition can be performed on both the P and N sides of the cell body at the same time. The selection and setting are based on the functional settings of the vacuum deposition equipment, and no specific requirements are given here.

[0122] The deposited metals on the P-side and N-side of the cell body are different. The deposited metals on the P-side and N-side of the cell body are selected and set according to actual needs, and no specific requirements are made here. The above-mentioned deposited metal materials include silver, cobalt, tungsten, nickel, vanadium, gold, titanium, aluminum or alloys, that is, the deposited metal material can be a metal element, and the metal element includes silver, cobalt, tungsten, nickel, vanadium, gold, titanium or aluminum, or the deposited metal material can also be a metal alloy, and the metal alloy includes silver alloy, cobalt alloy, tungsten alloy, nickel alloy, vanadium alloy, gold alloy, titanium alloy or aluminum alloy. The deposited metal material is selected and set according to actual needs, and no specific requirements are made here.

[0123] The thickness of the deposited metal is 5nm-200nm. The thickness of the deposited metal is selected and set according to actual needs. No specific requirements are given here. When depositing metal on the battery cell body, the thickness of the deposited metal is controlled by controlling the power of the vacuum deposition equipment. The deposition power of the vacuum deposition equipment is 1-10KW / CM 2 , select according to actual needs, no specific requirements are made here.

[0124] During metal deposition, the metal deposition time is 3-300s. The metal deposition time is selected according to actual needs and no specific requirements are given here.

[0125] In some feasible embodiments, preferably, an aluminum metal layer is deposited on the P side of the battery cell body, and the thickness of the aluminum metal layer is 5-200 nm, and a nickel metal layer is deposited on the N side of the battery cell body, and the thickness of the nickel metal layer is 5-200 nm.

[0126] After the metal deposition is completed, the cell body after metal deposition is annealed in the deposition chamber of the vacuum deposition equipment to form an ohmic contact layer 8. In the annealing step after deposition, the annealing temperature is 200-650°C and the annealing time is 30-300s. The annealing temperature and annealing time are selected according to actual needs and no specific requirements are made here.

[0127] The thickness of the ohmic contact layer 8 is 1-100 nm. The thickness of the ohmic contact layer 8 is selected and set according to actual needs, and no specific requirements are made here.

[0128] The annealed cell body is etched to remove the deposited metal in other areas of the P-side and N-side of the cell body except the electrode opening area, that is, the deposited metal on the passivation tunneling layer 7 on the P-side of the cell body and the deposited metal on the anti-reflection layer 4 on the N-side of the cell body are removed, and only the ohmic contact layer prepared by the reaction in the electrode opening area is retained. The annealed cell body is etched with an etching solution, the etching temperature is 20-60°C, and the etching time is 1-30 minutes. The etching temperature and etching time are selected according to actual needs and no specific requirements are made here.

[0129] The above-mentioned etching solution includes hydrochloric acid, formic acid and sodium hydroxide. The mass percentage of hydrochloric acid in the etching solution is 1%-15%, the mass percentage of formic acid in the etching solution is 3%-20%, and the mass percentage of sodium hydroxide in the etching solution is 3%-15%. The mass percentages of hydrochloric acid, formic acid and sodium hydroxide in the etching solution are selected according to actual needs and no specific requirements are made here.

[0130] After etching is completed, the passivation tunneling layer 7 and the ohmic contact layer 8 form a composite conductive layer, which reduces surface recombination and the defect state density on the cell surface, thereby reducing the recombination rate of carriers on the surface and reducing contact resistance.

[0131] After etching is completed, a bonding layer 9, an electrode layer 10 and a protective layer 11 are sequentially prepared in the electrode opening area. Figure 4-6 As shown, in the electrode opening area, a bonding layer 9 is prepared on the ohmic contact layer 8, an electrode layer 10 is prepared on the bonding layer 9, and a protective layer 11 is prepared on the electrode layer 10. At the same time, the protective layer 11 wraps the sides of the bonding layer 9 and the electrode layer 10 to protect the sides of the bonding layer 9 and the electrode layer 10.

[0132] The above-mentioned bonding layer 9, electrode layer 10 and protective layer 11 are all metal layer structures, and the bonding layer 9, electrode layer 10 and protective layer 11 are all prepared by wet electroplating deposition process, wherein the material of the bonding layer 9 includes nickel, tungsten, silver or titanium, and the thickness of the bonding layer 9 is 0.1-3um. The material and thickness of the bonding layer 9 are selected according to actual needs, and no specific requirements are made here; the material of the electrode layer 10 includes copper, and the thickness of the electrode layer 10 is 5-50um. The material and thickness of the electrode layer 10 are selected according to actual needs, and no specific requirements are made here; the material of the protective layer 11 includes nickel, tin or silver, and the thickness of the protective layer 11 is 0.1-3um. The material and thickness of the protective layer 11 are selected according to actual needs, and no specific requirements are made here.

[0133] After the protective layer 11 is prepared, a cell with a composite conductive layer is obtained.

[0134] A battery cell with a composite conductive layer is prepared using the above-mentioned method for preparing a battery cell with a composite conductive layer, such as Figure 6 As shown, it includes a battery cell body, and the P side and N side of the battery cell body are respectively provided with at least one electrode opening area, and the electrode opening area of the P side of the battery cell body is sequentially provided with a passivation tunneling layer 7, an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11, and the passivation tunneling layer 7 is provided in the area other than the electrode opening area of the P side of the battery cell body, and the electrode opening area of the N side of the battery cell body is sequentially provided with an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11.

[0135] Specifically, the above-mentioned battery cell body includes a liner 1. On the P side of the liner 1, a P electrode 2 layer is arranged in the electrode opening area, and the area outside the electrode opening area is sequentially provided with a P electrode 2 layer, an aluminum oxide layer 3 and an anti-reflection layer 4; on the N side of the liner 1, a silicon dioxide layer 5 and an N electrode 6 layer are sequentially provided in the electrode opening area, and the area outside the electrode opening area is sequentially provided with a silicon dioxide layer 5, an N electrode 6 layer and an anti-reflection layer 4.

[0136] On the P surface of the battery cell body, the passivation tunneling layer 7 is arranged in the electrode opening area and the area outside the electrode opening area, that is, the passivation tunneling layer 7 covers the P surface of the battery cell body, and the passivation tunneling layer 7 is arranged on the P electrode 2 layer in the electrode opening area and on the anti-reflection layer 4 in the area outside the electrode opening area.

[0137] On the P-side of the cell body, in the electrode opening region, an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11 are sequentially provided on the passivation tunneling layer 7.

[0138] On the N side of the cell body, in the electrode opening region, an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11 are sequentially provided on the N electrode 6 layer.

[0139] The thickness of the passivation tunneling layer 7 is 1-5 nm, and the material of the passivation tunneling layer 7 is silicon oxide, aluminum oxide, nickel oxide or titanium oxide.

[0140] The thickness of the ohmic contact layer 8 is 1-100 nm.

[0141] The following detailed description takes the TOPCon battery cell as an example.

[0142] A method for preparing a battery cell with a composite conductive layer comprises the following steps:

[0143] A cell body is provided, which is a cell body with anti-reflection layers 4 prepared on both sides. The cell body includes a silicon substrate 1, a silicon dioxide layer 5, an N electrode 6 and an anti-reflection layer 4 arranged on the N side of the silicon substrate 1, and a P electrode 2, an aluminum oxide layer 3 and an anti-reflection layer 4 arranged on the P side of the silicon substrate 1.

[0144] The P side and N side of the battery cell body are respectively grooved graphically by laser grooving to form electrode opening areas: the position of the electrode is determined according to the electrode design requirements of the battery cell, and the corresponding positions on the two side surfaces of the battery cell body prepared with the anti-reflection layer 4 are grooved by laser. On the N side of the battery cell body, the anti-reflection layer 4 at the corresponding position is removed, and on the P side of the battery cell body, the anti-reflection layer 4 and the aluminum oxide layer 3 at the corresponding position are removed to form the electrode opening area, thereby completing the electrode pattern preparation of the P side and N side of the battery cell body.

[0145] In this embodiment, the silicon liner 1 is an N-type silicon liner 1 , and the antireflection layer 4 is silicon nitride.

[0146] Thermally repair the slotted cell body to form an oxide layer in the electrode opening area: Place the slotted cell body in a tunnel furnace and heat it at 700°C for 80 seconds to form an oxide layer in the electrode opening area. This oxide layer is silicon oxide.

[0147] The heat-treated cell body is acid-treated to remove the oxide layer and impurities. The heat-treated cell body is cleaned with 1.5% hydrofluoric acid to remove silicon oxide and impurities in the electrode opening area. The acid treatment time is 100 seconds.

[0148] The cleaned cell body is placed in a vacuum deposition device, and a passivation tunneling layer 7 is prepared on the P surface of the cell body by chemical vapor deposition or plasma enhanced chemical vapor deposition. When the chemical vapor deposition method is used, the reaction source is trimethylaluminum, the flow rate of the reaction source is 10-50 sccm, the oxygen source is oxygen, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-400°C, and the reaction time is 30-600s. The reaction generates an aluminum oxide layer, which is the passivation tunneling layer 7. The thickness of the aluminum oxide layer is 1-5nm.

[0149] When plasma-enhanced chemical vapor deposition is used, the reaction gas is trimethylaluminum and O2 mixed in a ratio of 1:30, the flow rate of the trimethylaluminum and oxygen mixture is 10-100 sccm, the reaction power is 100-300 W, the reaction temperature is 200-500° C., and the reaction time is 30-600 s. The reaction forms an aluminum oxide layer, which is the passivation tunneling layer 7. The thickness of the aluminum oxide layer is 1-5 nm.

[0150] The cell body with the passivation tunneling layer 7 prepared is placed in a vacuum deposition device for metal deposition. A metal deposition layer is formed on the P side and N side of the cell body respectively. When metal deposition is performed in the vacuum deposition device, the power of the vacuum deposition device is 5KW / CM 2 The deposition time is 100s, and the P-side metal deposition and the N-side metal deposition are carried out simultaneously. The metal deposited on the P-side is different from the metal deposited on the N-side. Aluminum metal is vacuum sputtered on the P-side to form an aluminum metal deposition layer on the P-side, and nickel metal is vacuum sputtered on the N-side to form a nickel metal deposition layer on the N-side.

[0151] After the deposition time is reached, the metal deposition is completed, and the deposited cell body is annealed in a vacuum deposition device. The annealing time is 60s and the annealing temperature is 350°C. After the annealing is completed, an aluminum ohmic contact layer is prepared on the P side of the cell body. The thickness of the aluminum ohmic contact layer is 1-100nm. A nickel ohmic contact layer is prepared on the N side of the cell body. The thickness of the nickel ohmic contact layer is 1-100nm.

[0152] The annealed cell body is etched to remove the metal deposited layer from the non-electrode opening areas (excluding the electrode opening areas) on the P-side and N-side surfaces of the cell body: the annealed cell body is placed in an etchant for 5 minutes at a temperature of 60°C. The etchant is a mixed solution of hydrochloric acid and formic acid, wherein the mass percentage of hydrochloric acid in the etchant is 3% and the mass percentage of formic acid in the etchant is 5%. After the etching process is completed, the etched cell body is cleaned with pure water to remove the etchant from the cell body so that the cell can be subsequently electroplated.

[0153] When the battery cell body is etched, the aluminum metal layer at the non-electrode area on the P side of the battery cell body and the nickel metal layer at the non-electrode area on the N side are removed to expose the anti-reflection layer 4 at the non-electrode area on the P side of the battery cell body and the anti-reflection layer 4 at the non-electrode area on the N side of the battery cell body. An aluminum-silicon alloy reaction layer is formed in the electrode opening area on the P side of the battery cell, that is, the ohmic contact layer 8 structure of the P side. A nickel-silicon reaction layer is formed in the electrode opening area on the N side of the battery cell, that is, the ohmic contact layer 8 structure of the N side. After etching, a battery cell to be electroplated with an electrode opening area is obtained, and then the battery cell is electroplated to prepare a metal electrode.

[0154] The bonding layer 9 is prepared on the etched cell by electroplating process, and the bonding layer 9 is formed at the electrode opening area of the P side and N side of the cell respectively. The bonding layer 9 is a metal layer, and the material of the bonding layer 9 is preferably nickel. The thickness of the bonding layer 9 is 3um.

[0155] The electrode layer 10 is prepared on the battery cell with the bonding layer 9 completed by electroplating process, and the electrode layer 10 is formed on the bonding layer 9 at the electrode opening area of the P side and N side of the battery cell respectively. The material of the electrode layer 10 is copper and the thickness of the electrode layer 10 is 8um.

[0156] The protective layer 11 is prepared on the battery cell with the electrode layer 10 completed by the electroplating process. The protective layer 11 is formed on the electrode layer 10 at the electrode opening area on the P side and the N side of the battery cell respectively. The protective layer 11 is located on the upper surface of the electrode layer 10 and wraps the side edges of the bonding layer 9 and the electrode layer 10 to protect the side edges of the bonding layer 9 and the electrode layer 10. The protective layer 11 is a metal layer, the material of the protective layer 11 is tin, and the thickness of the protective layer 11 is 1um.

[0157] The cell on which the protective layer 11 is prepared is cleaned to remove the plating solution and particulate impurities on the cell, and the cleaned cell is blown dry to obtain a cell with a composite conductive layer.

[0158] When chemical vapor deposition is used to form a passivation tunneling layer 7 on the P-side of the cell body within a vacuum deposition apparatus, the vacuum deposition apparatus is controlled at different power levels while maintaining the same reaction source flow rate, oxygen source flow rate, reaction temperature, and reaction time (for example, a flow rate of 30 sccm for the reaction source trimethylaluminum, a flow rate of 200 sccm for the oxygen source oxygen, a reaction temperature of 300°C, and a reaction time of 60 seconds) to produce passivation tunneling layers 7 of varying thicknesses. Simultaneously, during the ohmic contact layer 8 preparation process, the vacuum deposition apparatus is controlled at different power levels to produce ohmic contact layers 8 of varying thicknesses, as described in Examples 1 to 6 below.

[0159] In the first embodiment, the passivation tunneling layer 7 is aluminum oxide, the thickness of the passivation tunneling layer 7 is 1.67 nm, the thickness of the P-side ohmic contact layer is 12.7 nm, and the thickness of the N-side ohmic contact layer is 12.4 nm.

[0160] In the second embodiment, the passivation tunneling layer 7 is aluminum oxide, the thickness of the passivation tunneling layer 7 is 1.66 nm, the thickness of the P-side ohmic contact layer is 12.6 nm, and the thickness of the N-side ohmic contact layer is 12.7 nm.

[0161] In the third embodiment, the passivation tunneling layer 7 is aluminum oxide, the thickness of the passivation tunneling layer 7 is 2.55 nm, the thickness of the P-side ohmic contact layer is 12.7 nm, and the thickness of the N-side ohmic contact layer is 12.7 nm.

[0162] In the fourth embodiment, the passivation tunneling layer 7 is aluminum oxide, the thickness of the passivation tunneling layer 7 is 2.58 nm, the thickness of the P-side ohmic contact layer is 12.7 nm, and the thickness of the N-side ohmic contact layer is 12.5 nm.

[0163] In the fifth embodiment, the passivation tunneling layer 7 is aluminum oxide, the thickness of the passivation tunneling layer 7 is 3.57 nm, the thickness of the P-side ohmic contact layer is 12.6 nm, and the thickness of the N-side ohmic contact layer is 12.6 nm.

[0164] In the sixth embodiment, the passivation tunneling layer 7 is aluminum oxide, the thickness of the passivation tunneling layer 7 is 3.38 nm, the thickness of the P-side ohmic contact layer is 12.6 nm, and the thickness of the N-side ohmic contact layer is 12.6 nm.

[0165] Next, a passivation tunneling layer 7 is prepared using TiCl4 as a reaction source or a mixture of TiCl4 and O2 in a ratio of 1:30 as a reaction gas. The preparation process is the same as the above-mentioned process steps. When the passivation tunneling layer 7 is prepared on the P-side of the solar cell body in a vacuum deposition apparatus using chemical vapor deposition or plasma-enhanced chemical vapor deposition, the vacuum deposition apparatus power is controlled to different powers, and the same reaction gas flow rate, reaction temperature, and reaction time are selected (for example: the flow rate of the reaction source TiCl4 is 30 sccm, the flow rate of the oxygen source oxygen is 550 sccm, the reaction temperature is 450°C, and the reaction time is 60 seconds). Passivation tunneling layers 7 of varying thicknesses are prepared. Simultaneously, during the preparation process of the ohmic contact layer 8, the power of the vacuum deposition apparatus is controlled to different powers to prepare ohmic contact layers 8 of varying thicknesses, as shown in the following Examples 7 to 12.

[0166] In the seventh embodiment, the passivation tunneling layer 7 is titanium oxide, the thickness of the passivation tunneling layer 7 is 1.57 nm, the thickness of the P-side ohmic contact layer is 12.5 nm, and the thickness of the N-side ohmic contact layer is 12.7 nm.

[0167] In the eighth embodiment, the passivation tunneling layer 7 is titanium oxide, the thickness of the passivation tunneling layer 7 is 1.56 nm, the thickness of the P-side ohmic contact layer is 12.7 nm, and the thickness of the N-side ohmic contact layer is 12.6 nm.

[0168] In the ninth embodiment, the passivation tunneling layer 7 is titanium oxide, the thickness of the passivation tunneling layer 7 is 2.85 nm, the thickness of the P-side ohmic contact layer is 12.7 nm, and the thickness of the N-side ohmic contact layer is 12.6 nm.

[0169] In the tenth embodiment, the passivation tunneling layer 7 is titanium oxide, the thickness of the passivation tunneling layer 7 is 2.85 nm, the thickness of the P-side ohmic contact layer is 12.5 nm, and the thickness of the N-side ohmic contact layer is 12.7 nm.

[0170] In the eleventh embodiment, the passivation tunneling layer 7 is titanium oxide, the thickness of the passivation tunneling layer 7 is 4.12 nm, the thickness of the P-side ohmic contact layer is 12.6 nm, and the thickness of the N-side ohmic contact layer is 12.6 nm.

[0171] In the twelfth embodiment, the passivation tunneling layer 7 is titanium oxide, the thickness of the passivation tunneling layer 7 is 4.11 nm, the thickness of the P-side ohmic contact layer is 12.6 nm, and the thickness of the N-side ohmic contact layer is 12.6 nm.

[0172] The battery cells prepared in the above twelve embodiments were measured for Eta (conversion efficiency), Voc (open circuit voltage), FF (fill factor) and Rs (resistance), where Eta is the conversion efficiency, Voc is the open circuit voltage, FF is the fill factor, and Rs is the resistance. Control group 1 consisted of battery cells without a passivation tunneling layer (P-side) and with an ohmic contact layer (the ohmic contact layers on the P-side and N-side were both made of nickel); control group 2 consisted of battery cells without a passivation tunneling layer (P-side) and with an ohmic contact layer (the ohmic contact layer on the P-side was made of aluminum, and the ohmic contact layer on the N-side was made of nickel); test groups 1 to 6 were battery cells prepared using the methods of Examples 1 to 6 above, and the material of the passivation tunneling layer was aluminum oxide; test groups 7 to 12 were battery cells prepared using the methods of Examples 7 to 12 above, and the material of the passivation tunneling layer was titanium oxide. The test results are shown in Table 1 below.

[0173] Table 1 Comparison of Eta, Voc, FF, and Rs parameters between the experimental and control groups

[0174]

[0175] As can be seen from the table above, the measured data show that the Eta, Voc, and FF of the cell are all improved, while Rs is reduced. In particular, the open-circuit voltage of the cell with a passivation tunneling layer is significantly increased, indicating that the provision of a passivation tunneling layer can repair the anti-reflection layer of the original cell that was previously damaged by laser grooving; and the ohmic contact layer also repairs the doping layer of the original cell that was damaged by laser grooving, thereby increasing the open-circuit voltage of the cell and reducing the contact resistance. Therefore, the conversion efficiency and fill factor of the obtained cell are both improved.

[0176] Example 2

[0177] Compared with Example 1, the difference between this embodiment is the step of preparing a passivation tunneling layer on the P side of the battery cell body and the step of preparing an ohmic contact layer in the electrode opening areas on the P side and N side of the battery cell body. The other steps are the same.

[0178] A method for preparing a battery cell with a composite conductive layer comprises the following steps:

[0179] The P side and N side of the cell body are patterned and grooved to form electrode opening areas, exposing the P electrode 2 and the N electrode 6, so as to facilitate the subsequent setting of the passivation tunneling layer 7 and the ohmic contact layer 8. Figure 1 As shown, according to the design requirements of the battery cell structure, graphic grooves are performed at the designed positions of the P and N sides of the battery cell to provide a basis for the subsequent preparation of the passivation tunneling layer 7, the ohmic contact layer 8 and the metal electrode. When the battery cell body is graphic grooved, the P side of the battery cell body is graphic grooved, the passivation tunneling layer 7 and the ohmic contact layer 8 are prepared on the P side of the battery cell body, the N side of the battery cell body is graphic grooved, and the ohmic contact layer 8 is prepared on the N side of the battery cell body. The setting position of the graphic groove is selected and set according to the type of the battery cell body and the actual structural design requirements of the battery cell, and no specific requirements are made here.

[0180] The above-mentioned cell body is a cell on which the anti-reflection layer 4 is prepared. For example, the cell body can be a TOPCon cell prepared with an anti-reflection layer 4. The cell body includes a liner 1, and a P electrode 2, an aluminum oxide layer 3 and an anti-reflection layer 4 are arranged in sequence on the P surface of the liner 1, and a silicon dioxide layer 5, an N electrode 6 and an anti-reflection layer 4 are arranged in sequence on the N surface of the liner 1.

[0181] When patterning the cell body, laser grooves are performed on the cell body where metal electrodes are required. On the P side of the cell body, the aluminum oxide layer 3 and anti-reflection layer 4 are removed at the corresponding locations, exposing the P electrode 2 beneath the aluminum oxide layer 3 and anti-reflection layer 4. On the N side of the cell body, the anti-reflection layer 4 is removed at the corresponding locations, exposing the N electrode 6 beneath the anti-reflection layer 4, forming an electrode opening area. The subsequently prepared ohmic contact layer 8 is disposed in this electrode opening area so that the metal electrode forms effective contact with the semiconductor through the ohmic contact layer 8, facilitating the input and output of current. Here, the grooved area is the electrode opening area, and the area outside the grooved area is the non-electrode opening area.

[0182] After the cell body is laser grooved, a passivation tunneling layer is prepared on the P surface of the cell body, such as Figure 7 As shown, the passivation tunneling layer 7 is prepared by heat treatment, specifically: the battery cell after the groove is completed is placed in a tunnel furnace and placed in an atmospheric atmosphere for heating treatment. The heat treatment temperature is 550-900°C and the heat treatment time is 5-120s. By controlling the temperature and time of the heat treatment, an oxide layer is formed at the groove. The oxide layer is the passivation tunneling layer 7. Therefore, the material of the passivation tunneling layer 7 is silicon oxide.

[0183] In this embodiment, the heat treatment temperature can be 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, or any temperature value between 550-900℃. It can be selected and set according to actual needs, and no specific requirements are made here.

[0184] In this embodiment, the heat treatment time is 20s, 40s, 60s, 80s, 100s, 120s, or any other time value between 5-120s. It is selected and set according to actual needs, and no specific requirements are made here.

[0185] The thickness of the passivation tunneling layer 7 is 1-5nm, which is a passivation tunneling layer 7 of nano-physical scale. It can avoid the result of the open-circuit voltage of the solar cell decreasing due to the previous removal of the local anti-reflection layer 4, and achieve the open-circuit voltage of the solar cell not decreasing. At the same time, the passivation tunneling layer 7 can effectively inhibit the recombination of photogenerated electrons and holes, overall extend the light-hole migration efficiency, and reduce the contact resistance.

[0186] In this embodiment, the thickness of the passivation tunneling layer 7 can be 1nm, 2nm, 3nm, 4nm, 5nm, or any other thickness value between 1-5nm. The thickness of the passivation tunneling layer 7 is selected and set according to actual needs, and no specific requirements are given here. Figure 8 As shown, after the passivation tunneling layer 7 is prepared, the ohmic contact layer 8 is prepared in the electrode opening areas of the P-side and N-side of the battery body, including:

[0187] A first metal is deposited on the N-side of the heat-treated battery cell body to form a first metal layer. The first metal is deposited by electroplating or light-induced electroplating, which is selected according to actual needs.

[0188] The thickness of the above-mentioned first metal layer is 500-1000nm. The thickness of the first metal layer can be 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, etc., any thickness value between 500-1000nm. The thickness of the first metal layer is selected according to actual needs, and no specific requirements are made here.

[0189] After the first metal is deposited, a second metal is deposited on the P side of the heat-treated battery cell body to form a second metal layer. The second metal is deposited by magnetron sputtering or evaporation, which is selected according to actual needs.

[0190] The thickness of the above-mentioned second metal layer is 5-200nm. The thickness of the second metal layer can be 5nm, 50nm, 100nm, 150nm, 200nm, or any other thickness value between 5-200nm. The thickness of the second metal layer is selected according to actual needs and no specific requirements are made here.

[0191] The material of the above-mentioned second metal layer is different from the material of the first metal layer. The material of the first metal layer and the material of the second metal layer both include silver, cobalt, tungsten, nickel, vanadium, gold, titanium, aluminum or an alloy. That is, the deposited metal material can be a metal element, which includes silver, cobalt, tungsten, nickel, vanadium, gold, titanium or aluminum, or the deposited metal material can also be a metal alloy, which includes a silver alloy, cobalt alloy, tungsten alloy, nickel alloy, vanadium alloy, gold alloy, titanium alloy or aluminum alloy.

[0192] In this embodiment, preferably, the material of the first metal layer is nickel, and the material of the second metal layer is aluminum.

[0193] After the second metal is deposited, annealing treatment is performed to prepare an ohmic contact layer 8. An ohmic contact layer 8 is formed at the electrode opening area on the N side of the battery cell body and the electrode opening area on the P side of the battery cell body. After the second metal is deposited, the battery cell body after the second metal deposition is annealed in the deposition chamber of the vacuum deposition equipment. The annealing step is performed in a vacuum heating chamber with a vacuum degree of 10E-5-10E-7Torr, an annealing temperature of 200-650°C, and an annealing time of 30-300s. The annealing temperature and annealing time are selected according to actual needs and no specific requirements are made here.

[0194] The thickness of the ohmic contact layer 8 is 1-100 nm. The thickness of the ohmic contact layer 8 is selected and set according to actual needs, and no specific requirements are made here.

[0195] The annealed cell body is etched to remove the first metal deposited in other areas of the N-side of the cell body except the electrode opening area and the second metal deposited in other areas of the P-side of the cell body except the electrode opening area, that is, the second metal on the anti-reflection layer 4 on the P-side of the cell body and the first metal on the anti-reflection layer 4 on the N-side of the cell body are removed, and only the ohmic contact layer prepared by the reaction in the electrode opening area is retained. The annealed cell body is etched with an etching solution at an etching temperature of 20-60°C and an etching time of 1-30 minutes. The etching temperature and etching time are selected according to actual needs and no specific requirements are made here.

[0196] The above-mentioned etching solution includes hydrochloric acid, formic acid and sodium hydroxide. The mass percentage of hydrochloric acid in the etching solution is 1%-15%, the mass percentage of formic acid in the etching solution is 3%-20%, and the mass percentage of sodium hydroxide in the etching solution is 3%-15%. The mass percentages of hydrochloric acid, formic acid and sodium hydroxide in the etching solution are selected according to actual needs and no specific requirements are made here.

[0197] After etching is completed, the passivation tunneling layer 7 and the ohmic contact layer 8 form a metal-doped silicon oxide layer, which plays the role of passivation, tunneling and conductivity. The passivation tunneling layer 7 and the ohmic contact layer (aluminum metal) are prepared in the electrode opening area of the P side of the battery cell body to form aluminum silicon oxide, which can effectively repair the damage to the passivation layer during laser grooving, improve the open circuit voltage of the battery, increase the conductivity of the oxide, and reduce the difficulty of subsequent electroplating to prepare the bonding layer 9, electrode layer 10 and protective layer 11; the ohmic contact layer (nickel metal) is prepared in the electrode opening area of the N side of the battery cell body to form nickel silicon oxide, which effectively reduces the series resistance and improves the FF of the battery.

[0198] After etching is completed, a bonding layer 9, an electrode layer 10 and a protective layer 11 are sequentially prepared in the electrode opening area. Figure 9-11 As shown, in the electrode opening area, a bonding layer 9 is prepared on the ohmic contact layer 8, an electrode layer 10 is prepared on the bonding layer 9, and a protective layer 11 is prepared on the electrode layer 10. At the same time, the protective layer 11 wraps the sides of the bonding layer 9 and the electrode layer 10 to protect the sides of the bonding layer 9 and the electrode layer 10.

[0199] The above-mentioned bonding layer 9, electrode layer 10 and protective layer 11 are all metal layer structures, and the bonding layer 9, electrode layer 10 and protective layer 11 are all prepared by wet electroplating deposition process, wherein the material of the bonding layer 9 includes nickel, tungsten, silver or titanium, and the thickness of the bonding layer 9 is 0.1-3um. The material and thickness of the bonding layer 9 are selected according to actual needs, and no specific requirements are made here; the material of the electrode layer 10 includes copper, and the thickness of the electrode layer 10 is 5-50um. The material and thickness of the electrode layer 10 are selected according to actual needs, and no specific requirements are made here; the material of the protective layer 11 includes nickel, tin or silver, and the thickness of the protective layer 11 is 0.1-3um. The material and thickness of the protective layer 11 are selected according to actual needs, and no specific requirements are made here.

[0200] After the protective layer 11 is prepared, a cell with a composite conductive layer is obtained.

[0201] A battery cell with a composite conductive layer is prepared using the method for preparing a battery cell with a composite conductive layer of this embodiment, such as Figure 11 As shown, it includes a battery cell body, and the P side and N side of the battery cell body are respectively provided with at least one electrode opening area, and the electrode opening area of the P side of the battery cell body is sequentially provided with a passivation tunneling layer 7, an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11, and the electrode opening area of the N side of the battery cell body is sequentially provided with an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11.

[0202] Specifically, the above-mentioned battery cell body includes a liner 1. On the P side of the liner 1, a P electrode 2 layer is arranged in the electrode opening area, and the area outside the electrode opening area is sequentially provided with a P electrode 2 layer, an aluminum oxide layer 3 and an anti-reflection layer 4; on the N side of the liner 1, a silicon dioxide layer 5 and an N electrode 6 layer are sequentially provided in the electrode opening area, and the area outside the electrode opening area is sequentially provided with a silicon dioxide layer 5, an N electrode 6 layer and an anti-reflection layer 4.

[0203] On the P surface of the cell body, in the electrode opening area, along the P surface of the cell body to the outside direction, a passivation tunneling layer 7, an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11 are sequentially arranged on the P electrode 2 layer.

[0204] On the N side of the cell body, in the electrode opening area, along the N side of the cell body to the outside, an ohmic contact layer 8, a bonding layer 9, an electrode layer 10 and a protective layer 11 are sequentially provided on the N electrode 6 layer.

[0205] The thickness of the passivation tunneling layer 7 is 1-5 nm, and the material of the passivation tunneling layer 7 is silicon oxide.

[0206] The thickness of the ohmic contact layer 8 is 1-100 nm.

[0207] The above-mentioned method for preparing a battery cell with a composite conductive layer is used to prepare a battery cell with a composite conductive layer. In the step of preparing a passivation tunneling layer 7 on the P side of the battery cell body by heat treatment, the temperature and time of the heat treatment are controlled to obtain a passivation tunneling layer 7 of different thicknesses. At the same time, in the step of preparing an ohmic contact layer 8 in the electrode opening areas of the P and N sides of the battery cell body, nickel metal is deposited on the N side of the battery cell body by electroplating, and the power of the electroplating equipment is controlled to different powers. Then, aluminum metal is deposited on the P side of the battery cell body by magnetron sputtering, and the power of the magnetron sputtering equipment is controlled to different powers. Then, annealing is performed to prepare an ohmic contact layer. A nickel-silicon ohmic contact layer is formed by reaction in the electrode opening area of the N side of the battery cell body, and an aluminum-silicon ohmic contact layer is formed by reaction in the electrode opening area of the P side of the battery cell body, thereby obtaining ohmic contact layers 8 of different thicknesses.

[0208] The parameters of the prepared battery cells are shown in Table 2 below. The prepared battery cells were measured for Eta (conversion efficiency), Voc (open circuit voltage), FF (fill factor) and Rs (resistance), where Eta is the conversion efficiency, Voc is the open circuit voltage, FF is the fill factor, and Rs is the resistance. The control group 1 is a battery cell without a passivation tunneling layer (P-side) and with an ohmic contact layer (the ohmic contact layers on the P-side and N-side are both made of nickel). The control group 2 is a battery cell without a passivation tunneling layer (P-side) and with an ohmic contact layer (the P-side ohmic contact layer is made of aluminum and the N-side ohmic contact layer is made of nickel). The thickness of the passivation tunneling layer, the thickness of the P-pole ohmic contact layer and the thickness of the N-pole ohmic contact layer of the battery cells in test groups 1 to 6 are different.

[0209] Table 2 Comparison of Eta, Voc, FF, and Rs parameters of cells in the experimental group and the control group

[0210]

[0211] As can be seen from the table above, the measured data show that the Eta, Voc, and FF of the cell are all improved, while Rs is reduced. In particular, the open-circuit voltage of the cell with a passivation tunneling layer is significantly increased, indicating that the provision of a passivation tunneling layer can repair the anti-reflection layer of the original cell that was previously damaged by laser grooving; and the ohmic contact layer also repairs the doping layer of the original cell that was damaged by laser grooving, thereby increasing the open-circuit voltage of the cell and reducing the contact resistance. Therefore, the conversion efficiency and fill factor of the obtained cell are both improved.

[0212] Due to the adoption of the above technical solution, when preparing the cell with a composite conductive layer, a passivation tunneling layer of a certain thickness is prepared on the P surface of the cell body after the laser groove is completed. After the passivation tunneling layer is prepared, an ohmic contact layer is prepared on the P surface and N surface of the cell body. The ohmic contact layer and the passivation tunneling layer constitute a composite conductive layer. The passivation tunneling layer can be continuously and evenly distributed on the P surface of the cell, or the passivation tunneling layer can be arranged at the groove of the P surface of the cell, and the thickness of the passivation tunneling layer is nanometer-level, which reduces the defect state density on the surface of the cell, thereby reducing the recombination rate of carriers on the surface, thereby avoiding the open circuit voltage (V oc) decreases, so that the open-circuit voltage of the original battery cell does not decrease; at the same time, the setting of the passivation tunneling layer can match the work function, which can effectively suppress the recombination of photogenerated electrons and holes, overall extend the light-hole migration efficiency and simultaneously reduce the contact resistance; the setting of the ohmic contact layer, the thickness of the ohmic contact layer is nanometer-level, so that the electroplating process of the thick electrode structure can achieve the maximum overall conversion efficiency improvement of the battery cell. Through the vacuum deposition process electroplating process and combined with the annealing process, a uniform and well-contacted ohmic contact layer can be obtained, thereby achieving the purpose of reducing the contact resistance of the battery cell, and combined with the subsequent electroplating process of the electrode structure, the conversion efficiency of the battery cell is improved and the production cost of the battery cell is reduced.

[0213] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a battery cell having a composite conductive layer, characterized by: The following steps are involved: The P-side and N-side of the battery cell body are respectively patterned to form electrode opening areas, exposing the P electrode and N electrode; Prepare a passivation tunneling layer on the P surface of the battery cell body; Prepare ohmic contact layers in the electrode opening areas on the P-side and N-side of the battery cell body; A bonding layer, an electrode layer and a protective layer are sequentially prepared in the electrode opening area.

2. The method for preparing a battery cell with a composite conductive layer according to claim 1, wherein: The thickness of the passivation tunneling layer is 1-5 nm.

3. The method for preparing a battery cell with a composite conductive layer according to claim 1 or 2, wherein: The passivation tunneling layer is prepared by heat treatment. The passivation tunneling layer is formed in the electrode opening area of the P surface of the battery cell body. The heat treatment temperature is 550-900° C. and the heat treatment time is 5-120 seconds.

4. The method for preparing a battery cell with a composite conductive layer according to claim 3, wherein: The passivation tunneling layer is made of silicon oxide.

5. The method for preparing a battery cell with a composite conductive layer according to claim 3, wherein: The step of preparing an ohmic contact layer in the electrode opening areas on the P-side and N-side of the battery cell body comprises: Depositing a first metal on the N-side of the heat-treated battery cell body to form a first metal layer; After the first metal is deposited, a second metal is deposited on the P surface of the heat-treated battery cell body to form a second metal layer; After the second metal is deposited, an annealing treatment is performed to prepare an ohmic contact layer.

6. The method for preparing a battery cell with a composite conductive layer according to claim 5, wherein: The first metal is deposited by electroplating or light-induced electroplating, and the thickness of the first metal layer is 500-1000 nm.

7. The method for preparing a battery cell with a composite conductive layer according to claim 6, wherein: The second metal is deposited by magnetron sputtering or evaporation, and the thickness of the second metal layer is 5-200 nm.

8. The method for preparing a battery cell with a composite conductive layer according to claim 7, wherein: The first metal layer and the second metal layer are made of different materials. The materials of the first metal layer and the second metal layer both include silver, cobalt, tungsten, nickel, vanadium, gold, titanium, aluminum or alloys.

9. The method for preparing a battery cell with a composite conductive layer according to any one of claims 5 to 8, wherein: When the second metal is annealed after deposition, the annealing temperature is 200-650° C. and the annealing time is 30-300 seconds.

10. The method for preparing a battery cell with a composite conductive layer according to claim 9, wherein: The annealed cell body is etched to remove the first metal deposited in other areas of the N-side of the cell body except the electrode opening area and the second metal deposited in other areas of the P-side of the cell body except the electrode opening area.

11. The method for preparing a battery cell with a composite conductive layer according to claim 1 or 2, characterized in that: The passivation tunneling layer is made of silicon oxide, aluminum oxide, nickel oxide or titanium oxide.

12. The method for preparing a battery cell with a composite conductive layer according to claim 11, wherein: The passivation tunneling layer is prepared by using a chemical vapor deposition method to control the flow of a reaction source, the flow of an oxygen source, the reaction temperature and the reaction time. The reaction source includes a silicon source, an aluminum source, a nickel source or a titanium source, and the oxygen source includes oxygen.

13. The method for preparing a battery cell with a composite conductive layer according to claim 12, wherein: The silicon source includes SiH4, the flow rate of the silicon source is 5-70 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-800°C, and the reaction time is 30-600s; The aluminum source includes trimethylaluminum, the flow rate of the aluminum source is 10-50 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-400° C., and the reaction time is 30-600 s; The nickel source includes Ni(CO)4, the flow rate of the nickel source is 10-50 sccm, the flow rate of the oxygen source is 50-500 sccm, the reaction temperature is 200-600°C, and the reaction time is 30-600s; The titanium source includes TiCl4, the flow rate of the titanium source is 5-70 sccm, the flow rate of the oxygen source is 400-800 sccm, the reaction temperature is 600-1000°C, and the reaction time is 30-600s.

14. The method for preparing a battery cell with a composite conductive layer according to claim 11, wherein: The passivation tunneling layer is prepared by adopting a plasma enhanced chemical vapor deposition method to control the flow rate, reaction temperature, reaction time and reaction power of the reaction gas, wherein the reaction gas includes a mixed gas of a silicon source and a nitrogen oxide compound or a mixed gas of an aluminum source and an oxygen source or a mixed gas of a nickel source and an oxygen source or a mixed gas of a titanium source and an oxygen source.

15. The method for preparing a battery cell with a composite conductive layer according to claim 14, wherein: The mixed gas of the silicon source and the nitrogen oxide compound includes SiH4 and N2O mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the silicon source and the nitrogen oxide compound is 10-100 sccm, the reaction power is 100-300 W, the reaction temperature is 200-400°C, and the reaction time is 30-600s; The mixed gas of the aluminum source and the oxygen source includes trimethylaluminum and O2 mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the aluminum source and the oxygen source is 10-100 sccm, the reaction power is 100-300 W, the reaction temperature is 200-500 ° C, and the reaction time is 30-600 s; The mixed gas of the nickel source and the oxygen source includes Ni(CO)4 and O2 mixed in a ratio of 1:1-1:30, the flow rate of the mixed gas of the nickel source and the oxygen source is 10-100 sccm, the reaction power is 100-300 W, the reaction temperature is 200-500°C, and the reaction time is 30-600s; The mixed gas of the titanium source and the oxygen source includes TiCl4 and O2 mixed in a ratio of 1:1-1:

30. The flow rate of the mixed gas of the titanium source and the oxygen source is 10-100 sccm, the reaction power is 100-300W, the reaction temperature is 300-600°C, and the reaction time is 30-600s.

16. The method for preparing a battery cell with a composite conductive layer according to any one of claims 12 to 15, characterized in that: Metal is deposited on the P and N sides of the cell body using PVD, and annealed after deposition to prepare an ohmic contact layer. The deposited metals on the P and N sides of the cell body are different, and the thickness of the ohmic contact layer is 1-100 nm.

17. The method for preparing a battery cell with a composite conductive layer according to claim 16, wherein: The thickness of the deposited metal is 5-200 nm, and the deposited metal material includes silver, cobalt, tungsten, nickel, vanadium, gold, titanium, aluminum or alloy.

18. The method for preparing a battery cell with a composite conductive layer according to claim 17, wherein: In the annealing step after deposition, the annealing temperature is 250-650° C. and the annealing time is 30-180 seconds.

19. The method for preparing a battery cell with a composite conductive layer according to claim 18, wherein: The annealed cell body is etched to remove the deposited metal in other areas of the P-side and N-side of the cell body except the electrode opening area.

20. The method for preparing a battery cell with a composite conductive layer according to claim 10 or 19, wherein: The annealed cell body is etched using an etching solution at a temperature of 20-60° C. for 1-30 minutes.

21. The method for preparing a battery cell with a composite conductive layer according to claim 20, wherein: The etching solution includes hydrochloric acid, formic acid and sodium hydroxide, the mass percentage of the hydrochloric acid in the etching solution is 1%-15%, the mass percentage of the formic acid in the etching solution is 3%-20%, and the mass percentage of the sodium hydroxide in the etching solution is 3%-15%.

22. The method for preparing a battery cell with a composite conductive layer according to any one of claims 1-2, 4-8, 10, 12-15, 17-19 and 21, characterized in that: The bonding layer, the electrode layer and the protective layer are all prepared by a wet electroplating deposition process, wherein: The material of the bonding layer includes nickel, tungsten, silver or titanium, and the thickness of the bonding layer is 0.1-3 μm; The material of the electrode layer includes copper, and the thickness of the electrode layer is 5-50 μm; The material of the protective layer includes nickel, tin or silver, and the thickness of the protective layer is 0.1-3 μm.

23. The method for preparing a battery cell with a composite conductive layer according to claim 11, wherein: Before preparing the passivation tunneling layer on the P surface of the battery cell, the battery cell body after the groove is sequentially subjected to thermal repair and acid treatment.

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