A dendrite-free electrochemical silver plating method

Abstract

This invention provides a dendrite-free electrochemical silver plating method, comprising: immersing a conductive substrate in an electroplating solution, using the conductive substrate as a working electrode, and performing plating to obtain a silver-plated substrate; the electroplating solution includes a silver source, ammonia, a chelating agent, a buffer, and an electrolyte. Compared with the prior art, this invention uses a combination of ammonia and a chelating agent, which effectively suppresses dendrite formation, and further improves the adhesion between the silver plating layer and the substrate by employing stepwise electrodeposition, thereby enhancing the conductivity and stability of the silver-plated substrate.

Description

Technical Field

[0001] This invention belongs to the field of electroplating technology, and particularly relates to a dendrite-free electrochemical silver plating method. Background Technology

[0002] As an excellent conductive material, metallic silver has a wide range of applications in electronic components, displays, and top electrodes of solar cells.

[0003] Traditional methods for preparing silver thin films include electroless plating, slot coating, spraying, and printing. However, these methods suffer from problems such as poor density, weak film adhesion, and poor controllability of film thickness. Electrochemical silver plating is simple and produces strong film adhesion, but it suffers from poor controllability of film morphology. Furthermore, in electrochemical silver plating using a silver-ammonia system, silver tends to grow in a dendritic pattern, leading to reduced film density and weakened adhesion between the plating and the substrate, thus affecting its conductivity and stability. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a dendrite-free electrochemical silver plating method.

[0005] This invention provides a dendrite-free electrochemical silver plating method, comprising:

[0006] A transparent conductive substrate is immersed in an electroplating solution, and a silver-plated substrate is obtained by using the transparent conductive substrate as the working electrode. The electroplating solution includes a silver source, a complexing agent, a buffer, and an electrolyte. The complexing agent includes a first complexing agent and a second complexing agent. The first complexing agent is ammonia.

[0007] Preferably, the concentration of the silver source in the electroplating solution is 0.02–1 mol / L; the concentration of the first complexing agent ammonia in the electroplating solution is 0.02–1 mol / L based on the effective components; the concentration of the second complexing agent in the electroplating solution is 0.02–1 mol / L; the concentration of the buffer in the electroplating solution is 0.001–0.15 mol / L; and the concentration of the electrolyte in the electroplating solution is 0.01–2 mol / L.

[0008] Preferably, based on the effective components, the molar ratio of the first complexing agent to the second complexing agent in the electroplating solution is (5-10):1.

[0009] Preferably, the transparent conductive substrate is selected from FTO, ITO, AZO glass or flexible transparent conductive substrate;

[0010] The silver source is selected from silver nitrate;

[0011] The second complexing agent is selected from one or more of phosphate chelating agents, ethylenediaminetetraacetic acid chelating agents, and alkanolamine chelating agents;

[0012] The buffer is selected from boric acid;

[0013] The electrolyte is selected from potassium nitrate and / or sodium nitrate.

[0014] Preferably, the chelating agent is selected from one or more of sodium phosphate, disodium ethylenediaminetetraacetate, and triethanolamine.

[0015] Preferably, the transparent conductive substrate is cleaned before being immersed in the electroplating solution;

[0016] The cleaning process involves ultrasonic cleaning with deionized water, acetone, and ethanol in sequence.

[0017] Preferably, the plating is performed in the presence of a counter electrode; the counter electrode is selected from platinum sheets or platinum mesh.

[0018] Preferably, the plating process specifically involves: first applying a current density of 20–50 mA / cm². 2 Apply plating for 0.1–1 s, then apply a current density of 0.01–5 mA / cm². 2 Apply plating for 1–20 minutes.

[0019] Preferably, the plating process specifically involves: first applying a current density of 40–50 mA / cm². 2 Apply plating for 0.3–0.5 seconds, then apply a current density of 0.1–1 mA / cm². 2 Apply plating for 1 to 10 minutes.

[0020] This invention provides a dendrite-free electrochemical silver plating method, comprising: immersing a conductive substrate in an electroplating solution, using the conductive substrate as a working electrode, and performing plating to obtain a silver-plated substrate; the electroplating solution includes a silver source, ammonia, a chelating agent, a buffer, and an electrolyte. Compared with the prior art, this invention uses a combination of ammonia and a chelating agent, which effectively suppresses dendrite formation, and further improves the adhesion between the silver plating layer and the substrate by employing stepwise electrodeposition, thereby enhancing the conductivity and stability of the silver-plated substrate. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the silver plating layer on the FTO transparent conductive glass after plating in Embodiment 1 of the present invention. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a dendrite-free electrochemical silver plating method, comprising: immersing a transparent conductive substrate in an electroplating solution, using the conductive substrate as a working electrode, and performing plating to obtain a silver-plated substrate; the electroplating solution includes a silver source, a complexing agent, a buffer, and an electrolyte; the complexing agent includes a first complexing agent and a second complexing agent; the first complexing agent is ammonia.

[0024] In this invention, there are no special restrictions on the source of any raw materials; they can be commercially available.

[0025] The transparent conductive substrate is FTO, ITO, AZO glass, or a flexible transparent conductive substrate.

[0026] In this invention, the transparent conductive substrate is preferably cleaned first; the cleaning is preferably performed by ultrasonic cleaning with deionized water, acetone and ethanol in sequence; the ultrasonic cleaning time is preferably 10 to 30 minutes, more preferably 15 to 25 minutes, and even more preferably 20 minutes; after cleaning, it is preferably dried with nitrogen gas.

[0027] The conductive substrate is then immersed in an electroplating solution comprising a silver source, a complexing agent, a buffer, and an electrolyte. The silver source can be any silver source known to those skilled in the art and is not particularly limited; in this invention, a soluble inorganic silver salt is preferred, and silver nitrate is more preferred. The concentration of the silver source in the electroplating solution is preferably 0.02–1 mol / L, more preferably 0.05–0.5 mol / L, and even more preferably 0.1–0.2 mol / L. Based on the effective components, the concentration of the first complexing agent in the electroplating solution is preferably 0.02–1 mol / L. The concentration of the second complexing agent is preferably 0.05–0.5 mol / L, more preferably 0.1–0.2 mol / L, and most preferably 0.15–0.2 mol / L; the second complexing agent is preferably one or more of phosphate chelating agents, ethylenediaminetetraacetic acid chelating agents, and alkanolamine chelating agents, more preferably one or more of sodium phosphate, disodium ethylenediaminetetraacetic acid, and triethanolamine; the concentration of the second complexing agent in the electroplating solution is preferably 0.02–1 mol / L, more preferably 0.02–0.5 mol / L, and more preferably 0.15–0.2 mol / L. The preferred concentration is 0.02–0.1 mol / L; based on the effective components, the molar ratio of the first complexing agent to the second complexing agent in the electroplating solution is preferably (5–10):1, more preferably (6–9):1, and even more preferably (7–8):1; the buffer is preferably boric acid; the concentration of the buffer in the electroplating solution is preferably 0.001–0.15 mol / L, more preferably 0.005–0.1 mol / L, and even more preferably 0.01–0.05 mol / L; the electrolyte is preferably an alkali metal salt, more preferably a nitrate. Potassium nitrate and / or sodium nitrate; the concentration of the electrolyte in the electroplating solution is preferably 0.01-2 mol / L, more preferably 0.01-1 mol / L, even more preferably 0.01-0.5 mol / L, and most preferably 0.05-0.1 mol / L; the electroplating solution can be prepared according to methods well known to those skilled in the art, and there are no special limitations. In this invention, it is preferred to first mix the silver source with water, then add ammonia and a complexing agent under stirring conditions to obtain a clear solution, and then add a buffer and electrolyte to obtain the electroplating solution.

[0028] Using a conductive substrate as the working electrode, plating is performed to obtain a silver-plated substrate. In this invention, a two-electrode system is preferably used for plating, i.e., the plating is performed in the presence of a counter electrode. The counter electrode is preferably a platinum sheet or platinum mesh. The plating is preferably performed using a constant current electrodeposition method. The plating is preferably performed using a step-by-step electrodeposition method. In this invention, the plating is preferably specifically performed by first applying a current density of 20–50 mA / cm². 2 Apply plating for 0.1–1 s, then apply a current density of 0.01–5 mA / cm². 2 Plating for 1–20 minutes; more preferably, plating with a current density of 30–50 mA / cm². 2Apply plating for 0.1–1 s, then apply a current density of 0.05–3 mA / cm². 2 Plating for 1–15 minutes; further optimization specifically involves: first applying a current density of 40–50 mA / cm². 2 Apply plating for 0.3–0.5 seconds, then apply a current density of 0.1–1 mA / cm². 2 Plating for 1–10 minutes; the optimal setting is as follows: first apply a current density of 40–50 mA / cm². 2 Apply plating for 0.3–0.5 seconds, then apply a current density of 0.2–1 mA / cm². 2 Apply plating for 1-5 minutes.

[0029] This invention employs a combination of a first complexing agent and a second complexing agent to effectively suppress dendrite formation. Furthermore, by using stepwise electrodeposition, a uniform and dense coating is formed, which improves the adhesion between the silver coating and the substrate, thereby enhancing the conductivity and stability of the silver-plated substrate.

[0030] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a dendrite-free electrochemical silver plating method provided by the present invention.

[0031] All reagents used in the following examples are commercially available.

[0032] Example 1

[0033] Electroplating solution includes the following materials:

[0034] Silver nitrate 0.1M;

[0035] Complexing agent 1: 0.16M 28% ammonia solution;

[0036] Complexing agent 2: Disodium ethylenediaminetetraacetate 0.02M;

[0037] Buffer: 0.01M boric acid;

[0038] Other additives: KNO3 0.05M.

[0039] (1) Cut the FTO transparent conductive glass into 2cm×1cm pieces, place them in deionized water, acetone and ethanol respectively for ultrasonic cleaning for 20min, blow them dry with nitrogen and store them for later use.

[0040] (2) Prepare the electroplating solution according to the above formula. First, dissolve 1.6987g of silver nitrate in 100ml of deionized water to prepare a 0.1M silver nitrate aqueous solution. Then, while stirring, add 1.08ml of 28% (volume ratio) ammonia water and 0.6724g of disodium ethylenediaminetetraacetate to obtain a clear solution.

[0041] (3) Add 0.06183g of buffer boric acid and 0.5055g of additive KNO3.

[0042] (4) Plating: Using the above-mentioned FTO transparent conductive glass as the working electrode and a 2cm×2cm platinum sheet as the counter electrode, a two-electrode system is adopted, and a constant current electrodeposition method is used. First, the current density is 50mA / cm. 2 Plating was applied for 0.3 seconds, followed by a current density of 0.2 mA / cm². 2 Apply plating for 5 minutes.

[0043] Example 2

[0044] Electroplating solution includes the following materials:

[0045] Silver nitrate: 0.1M;

[0046] Complexing agent 1: 0.16M 28% ammonia solution;

[0047] Complexing agent 2: Disodium ethylenediaminetetraacetate 0.02M;

[0048] Buffer: 0.01M boric acid;

[0049] Other additives: KNO3 0.05M.

[0050] (1) Cut the FTO transparent conductive glass into 2cm×1cm pieces, place them in deionized water, acetone and ethanol respectively for ultrasonic cleaning for 20min, blow them dry with nitrogen and store them for later use.

[0051] (2) Prepare the electroplating solution according to the above formula. First, dissolve 1.6987g of silver nitrate in 100ml of deionized water to prepare a 0.1M silver nitrate aqueous solution. Then, while stirring, add 1.08ml of 28% (volume ratio) ammonia water and 0.6724g of disodium ethylenediaminetetraacetate to obtain a clear solution.

[0052] (3) Add 0.06183g of buffer boric acid and 0.5055g of additive KNO3.

[0053] (4) Plating: Using the above-mentioned FTO transparent conductive glass as the working electrode and a 2cm×2cm platinum sheet as the counter electrode, a two-electrode system is adopted, and a constant current electrodeposition method is used. First, the current density is 50mA / cm. 2 Plating was applied for 0.3 seconds, followed by a current density of 1 mA / cm². 2 Apply plating for 1 minute.

[0054] Example 3

[0055] Electroplating solution includes the following materials:

[0056] Silver nitrate: 0.1M;

[0057] Complexing agent 1: 0.16M 28% ammonia solution;

[0058] Complexing agent 2: Disodium ethylenediaminetetraacetate 0.02M;

[0059] Buffer: 0.01M boric acid;

[0060] Other additives: KNO3 0.05M.

[0061] (1) Cut the FTO transparent conductive glass into 2cm×1cm pieces, place them in deionized water, acetone and ethanol respectively for ultrasonic cleaning for 20min, blow them dry with nitrogen and store them for later use.

[0062] (2) Prepare the electroplating solution according to the above formula. First, dissolve 1.6987g of silver nitrate in 100ml of deionized water to prepare a 0.1M silver nitrate aqueous solution. Then, while stirring, add 1.08ml of 28% (volume ratio) ammonia water and 0.6724g of disodium ethylenediaminetetraacetate to obtain a clear solution.

[0063] (3) Add 0.06183g of buffer boric acid and 1.011g of additive KNO3.

[0064] (4) Plating: Using the above-mentioned FTO transparent conductive glass as the working electrode and a 2cm×2cm platinum sheet as the counter electrode, a two-electrode system is adopted, and a constant current electrodeposition method is used. First, the current density is 50mA / cm. 2 Plating was applied for 0.3 seconds, followed by a current density of 0.2 mA / cm². 2 Apply plating for 5 minutes.

[0065] Comparative Example 1

[0066] Electroplating solution includes the following materials:

[0067] Silver nitrate: 0.1M;

[0068] Complexing agent 1: 0.16M 28% ammonia solution;

[0069] Buffer: 0.01M boric acid;

[0070] Other additives: KNO3 0.05M.

[0071] (1) Cut the FTO transparent conductive glass into 2cm×1cm pieces, place them in deionized water, acetone and ethanol respectively for ultrasonic cleaning for 20min, blow them dry with nitrogen and store them for later use.

[0072] (2) Prepare the electroplating solution according to the above formula. First, dissolve 1.6987g of silver nitrate in 100ml of deionized water to prepare a 0.1M silver nitrate aqueous solution. Then, while stirring, add 1.08ml of 28% (volume ratio) ammonia water and 0.6724g of disodium ethylenediaminetetraacetate to obtain a clear solution.

[0073] (3) Add 0.06183g of buffer boric acid and 0.5055g of additive KNO3.

[0074] (4) Plating: Using the above-mentioned FTO transparent conductive glass as the working electrode and a 2cm×2cm platinum sheet as the counter electrode, a two-electrode system is adopted, and a constant current electrodeposition method is used. First, the current density is 50mA / cm. 2 Plating was applied for 0.3 seconds, followed by a current density of 0.2 mA / cm². 2 Apply plating for 5 minutes.

[0075] Comparative Example 2

[0076] Electroplating solution includes the following materials:

[0077] Silver nitrate: 0.1M;

[0078] Complexing agent 1: 0.16M 28% ammonia solution;

[0079] Complexing agent 2: Disodium ethylenediaminetetraacetate 0.02M;

[0080] Buffer: 0.01M boric acid;

[0081] Other additives: KNO3 0.05M.

[0082] (1) Cut the FTO transparent conductive glass into 2cm×1cm pieces, place them in deionized water, acetone and ethanol respectively for ultrasonic cleaning for 20min, blow them dry with nitrogen and store them for later use.

[0083] (2) Prepare the electroplating solution according to the above formula. First, dissolve 1.6987g of silver nitrate in 100ml of deionized water to prepare a 0.1M silver nitrate aqueous solution. Then, while stirring, add 1.08ml of 28% (volume ratio) ammonia water and 0.6724g of disodium ethylenediaminetetraacetate to obtain a clear solution.

[0084] (3) Add 0.06183g of buffer boric acid and 0.5055g of additive KNO3.

[0085] (4) Plating: Using the aforementioned FTO transparent conductive glass as the working electrode and a 2cm×2cm platinum sheet as the counter electrode, a two-electrode system is employed, using a constant current electrodeposition method with a current density of 0.2mA / cm². 2 Apply plating for 5 minutes.

[0086] The FTO transparent conductive glass after silver plating in Example 1 was analyzed using a scanning electron microscope, and a scanning electron microscope image of its silver plating layer was obtained, as shown below. Figure 1 As shown.

[0087] The FTO transparent conductive glasses deposited in Examples 1-3 and Comparative Examples 1-2 were analyzed. The film thickness non-uniformity was measured using a step tester, with a thickness of 1 cm. 2 There were more than 10 internal test points, and the conductivity was tested using the four-probe method. The results are shown in Table 1.

[0088] Table 1. Results of non-uniformity and relative conductivity of the deposited FTO transparent conductive glass film.

[0089] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Film thickness non-uniformity ±10％ ±16％ ±14％ ±53％ ±32％ relative conductivity 100％ 85％ 94％ 63％ 40％ Membrane adhesion powerful middle powerful Difference Difference

Claims

1. A dendrite-free electrochemical silver plating method, characterized in that, include: A transparent conductive substrate is immersed in an electroplating solution, and a silver-plated substrate is obtained by using the transparent conductive substrate as the working electrode. The electroplating solution includes a silver source, a complexing agent, a buffer, and an electrolyte. The complexing agent includes a first complexing agent and a second complexing agent. The first complexing agent is ammonia. The concentration of the silver source in the electroplating solution is 0.02~1 mol / L; based on the effective components, the concentration of the first complexing agent in the electroplating solution is 0.1~0.2 mol / L; the concentration of the second complexing agent in the electroplating solution is 0.02~0.1 mol / L; the concentration of the buffer in the electroplating solution is 0.01~0.05 mol / L; and the concentration of the electrolyte in the electroplating solution is 0.05~0.1 mol / L. Based on the effective components, the molar ratio of the first complexing agent to the second complexing agent in the electroplating solution is (7~8):1; The second complexing agent is selected from disodium ethylenediaminetetraacetate; The buffer is selected from boric acid; The electrolyte is selected from potassium nitrate and / or sodium nitrate; The plating process specifically involves: first applying a current density of 40~50 mA / cm². 2 Apply plating for 0.3~0.5 s, then apply a current density of 0.1~1 mA / cm². 2 Apply plating for 1~10 minutes.

2. The method according to claim 1, characterized in that, The transparent conductive substrate is selected from FTO, ITO, AZO glass or flexible transparent conductive substrate; The silver source is selected from silver nitrate.

3. The method according to claim 1, characterized in that, The transparent conductive substrate is cleaned and then immersed in the electroplating solution; The cleaning process involves ultrasonic cleaning with deionized water, acetone, and ethanol in sequence.

4. The method according to claim 1, characterized in that, The plating is performed in the presence of a counter electrode; the counter electrode is selected from platinum sheets or platinum mesh.

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