A semi-solid lithium battery anode structure and its preparation method
A 3D porous copper structure was prepared on copper foil by electrochemical deposition, and active materials such as silicon and germanium were deposited. Combined with a carbon coating layer, the problems of low capacity and poor cycle performance of lithium-ion battery anode materials were solved, and efficient charge transport and stable battery performance were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YUNNAN UNIV
- Filing Date
- 2022-12-20
- Publication Date
- 2026-06-30
AI Technical Summary
Existing lithium-ion battery anode materials have low capacity, poor cycle performance, and poor rate performance. The complex micro-interfaces caused by traditional coating processes affect charge transport and pose safety hazards.
A semi-solid lithium-ion battery anode structure was prepared by electrochemical deposition. A stable charge transport mechanism was constructed using a 3D porous copper framework and a carbon coating layer. Active materials such as silicon and germanium were deposited on copper foil and coated with carbon materials by hydrogen bubble template method and electrophoretic deposition method to form a self-supporting structure.
It improves the cycling stability and charge transport efficiency of the material, reduces the impact of volume expansion of active materials, simplifies the process, and reduces costs.
Smart Images
Figure CN116093259B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery anode material preparation, and specifically relates to a semi-solid lithium battery anode structure and preparation method. Background Technology
[0002] The advantages of high energy density, high operating voltage, long cycle life, and environmental friendliness have made lithium-ion batteries the mainstream of rechargeable battery development today. Currently, the theoretical specific capacity of graphite, the anode material for commercially available lithium-ion batteries, is only 372 mAh / g. After prolonged charge-discharge cycles, its layered structure is prone to collapse, leading to a decrease in capacity and a significant shortening of lifespan. Furthermore, its performance is poor at high rates, and it poses safety hazards during rapid discharge, failing to meet the development needs of today's high-tech era.
[0003] Liquid electrolyte lithium-ion batteries remain the mainstream technology currently in use. Their negative electrode active layer is formed by coating granulated active materials. There are complex micro-interfaces between the surface of the active materials, the binder, and the granular active materials. The resulting physical and chemical factors will affect charge transport, making it difficult to control the overall charge transport of the electrode and hindering breakthroughs. Summary of the Invention
[0004] To address the problems of low battery capacity, poor cycle performance, poor rate performance, and the impact of traditional coating processes in current lithium-ion battery anode materials, this invention employs electrochemical deposition to successfully prepare a semi-solid lithium-ion battery anode structure. The active materials selected are silicon and germanium, which possess high theoretical specific capacity. The spatial buffering capacity of the 3D porous framework structure obtained by electrochemical deposition effectively alleviates the volume expansion of the active materials, thereby improving the material's cycle stability. Electrochemical deposition avoids the charge transport effects caused by the numerous complex micro-interfaces inherent in traditional coating processes. The continuous and stable Cu framework in the anode provides an efficient channel for electron transport, while the uniform and continuous carbon coating layer serves as a lithium-ion transport layer. The anode constructs positive and negative charge transport layers on opposite sides of the active layer, causing reverse flow of electron and ion transport within the active layer, establishing a stable and efficient charge transport mechanism.
[0005] Specifically, this invention first electrochemically deposits a 3D porous copper structure on a copper foil using a hydrogen bubble template method, then electrochemically deposits materials such as silicon and germanium on the 3D porous copper structure, and finally coats the surface of the 3D porous composite structure with carbon materials by electrophoretic deposition, thus obtaining an integrated self-supporting semi-solid lithium battery anode material.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for preparing a semi-solid lithium-ion battery anode material includes the following steps:
[0008] A. Electrochemical deposition of 3D porous copper structures on copper foil using the hydrogen bubble template method;
[0009] B. Deposition of active materials such as silicon and germanium on this structure;
[0010] C. Carbon material is then coated onto the surface of the 3D porous composite structure by electrophoretic deposition.
[0011] Further, the basic precipitation solution in step A is prepared by using deionized water as a solvent, first adding 0.1-0.5 mol / L CuSO4 and magnetically stirring until completely dissolved, then adding 0.1-2 mol / L electrolyte (one or both of Na2SO4 and NaH2PO4) and magnetically stirring for 5-10 min. Next, 1-3 mol / L H2SO4 is added and stirred for 5-10 min. Finally, one or both of 5-20 mmol / L HCl or 1-10 mg / L PEG are added and magnetically stirred for 5-10 min.
[0012] Furthermore, in step A, the copper foil has a thickness of 9 μm and a diameter of 18 mm. The copper foil is first ultrasonically acid-washed with 10% HCl for 5 minutes to remove the surface oxide layer, and then ultrasonically cleaned with anhydrous ethanol, acetone, and deionized water sequentially for 3-5 minutes. Finally, it is placed in a forced-air drying oven to dry for later use.
[0013] Furthermore, the electrochemical deposition in step A employs a three-electrode system, with the working electrode being the copper foil that has been cleaned and dried for later use, the counter electrode being a high-purity copper sheet with a thickness of 0.1 mm, and the reference electrode being one of a platinum mesh electrode, an Ag / AgCl electrode, a saturated calomel electrode, or a silver wire electrode.
[0014] Furthermore, the current density of the electrochemical deposition in step A is between 1 and 5 A / cm². 2 The time interval is between 10 and 100 seconds.
[0015] Furthermore, the sample after electrochemical deposition in step A is washed three times sequentially with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at a temperature between 50 and 100°C for 1 to 5 hours.
[0016] Further, in step B, the deposition solution is selected from one of CH4O, C3H6O, C3H8O, C4H6O, and C6H6 as the solvent, and 0.05–0.5 mol / L (C4H6O) is added first. 12 ClN, C8H 20 ClN, C 12 H 28 ClN and C 16 H 36After one or more electrolytes (ClN) are completely dissolved by stirring, 0.1-1 mol / L SiCl4 or GeCl4 is added dropwise and stirred until homogeneous.
[0017] Furthermore, the electrochemical deposition in step B employs a three-electrode system. The working electrode is the product from step A, the counter electrode is either a platinum mesh electrode or a graphite electrode, and the reference electrode is either a platinum mesh electrode, an Ag / AgCl electrode, a saturated calomel electrode, or a silver wire electrode. Because the chlorides of the active materials silicon and germanium readily react with water, the electrochemical deposition must be carried out in a glove box with a non-aqueous solvent system and a water and oxygen content both below 1 ppm.
[0018] Furthermore, in step B, the electrochemical deposition voltage is between -1 and -5V, and the time is between 10 and 150 minutes.
[0019] Furthermore, the sample electrochemically deposited in step B is washed three times sequentially with deoxygenated PC and anhydrous ethanol, and then dried in a vacuum drying oven at a temperature between 40 and 80°C for 1 to 5 hours.
[0020] Furthermore, the electrophoretic deposition in step C employs a dual-electrode system, with the working electrode being the sample prepared in step B, and the counter electrode being either a platinum mesh electrode or a graphite electrode.
[0021] Further, the preparation of the electrophoresis solution in step C is divided into two steps: Solution a: Weigh 10mg-100mg of PVP and dissolve it in an appropriate amount of deionized water. Stir magnetically until completely dissolved. Then, weigh 10mg-200mg of carbon material and grind it in an agate mortar for 10-60 minutes. Dissolve the carbon material in the above solution and sonicate for 1-3 hours. Solution b: Weigh 1-10mg of Mg(NO3)2·6H2O / Al(NO3)2·9H2O and add it to an appropriate amount of one or more of the following dispersants: C3H6O, C3H8O, and C2H6O. Stir magnetically until completely dissolved. Measure 1-10mL of solution a and add it to solution b. Stir magnetically for 1-3 hours and sonicate for 1-3 hours. The preparation of the carbon material electrophoresis solution is now complete.
[0022] Furthermore, the voltage used for electrophoresis in step C is between 10-150V, and the electrophoresis time is between 1 and 60 minutes; the sample after electrophoresis is naturally air-dried in the atmosphere.
[0023] Compared with traditional materials and processes, this invention has the following advantages:
[0024] (1) The self-supporting 3D porous copper structure rigid skeleton has excellent spatial buffering ability, which can effectively alleviate the volume expansion of active materials, thereby improving the material capacity and improving the material cycle stability.
[0025] (2) The integrated preparation method avoids the influence of physical and chemical factors on the electrochemical performance of materials caused by the complex micro-interface between the active material surface and the binder, as well as between the particulate active material and the active material caused by coating.
[0026] (3) The experimental process is simple, low-cost and efficient. Attached Figure Description
[0027] Figure 1 It is a 3D porous copper SEM.
[0028] Figure 2 It is a 3D porous Cu / Si composite material SEM.
[0029] Figure 3 It is a 3D Cu / Si / MWCNTs composite material SEM.
[0030] Figure 4 This is a comparison chart of charge-discharge cycle life.
[0031] Figure 5 This is a comparison chart of rate performance. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the implementation methods of this invention will be described in detail below with reference to the accompanying drawings.
[0033] Example 1
[0034] A semi-solid lithium-ion battery anode structure and its fabrication. This embodiment uses copper foil as a substrate for porous copper electrochemical deposition, followed by Si electrochemical deposition, and finally MWCNT coating. The fabrication method includes the following steps:
[0035] A. Electrochemical deposition of 3D porous copper structures on copper foil using the hydrogen bubble template method;
[0036] B. Si was deposited on the 3D porous copper structure by electrochemical deposition.
[0037] C. MWCNTs are coated on the surface of a 3D porous Cu / Si composite structure by electrophoretic deposition.
[0038] Implementation method of step A:
[0039] Copper foil pretreatment: First, ultrasonically pickle the copper foil with 10% HCl for 5 minutes to remove the surface oxide layer, and then ultrasonically clean it with acetone, anhydrous ethanol and deionized water for 3-5 minutes in sequence.
[0040] Preparation of deposition solution: Weigh 2.26 g CuSO4 and dissolve it in 63.1 mL of deionized water. Stir magnetically until completely dissolved. Then weigh 8.48 g NaH2PO4 and add it to the solution. Stir magnetically for 10 min. Next, add 5.8 mL H2SO4 dropwise. Weigh 0.14 mg PEG and measure 59 μL HCl. Add each solution sequentially and stir magnetically for 10 min. The porous copper deposition solution is now ready.
[0041] Electrochemical deposition: A three-electrode system was used for electrochemical deposition. The working electrode was a 9 μm thick, 18 mm diameter copper foil; the counter electrode was a 0.1 mm thick high-purity copper sheet; and the reference electrode was a platinum mesh electrode. The electrochemical deposition current density was 3 A / cm². 2 The time is 10 seconds.
[0042] Sample preparation after deposition: The deposited sample was washed three times each with deionized water and anhydrous ethanol. It was then dried in a vacuum drying oven at 80℃ for 3 hours.
[0043] Implementation method of step B:
[0044] Preparation of the sedimentation solution: C4H6O was selected as the solvent for the sedimentation solution. 39.1 mL of C4H6O was measured, and 1.15 g of C8H2O was weighed. 20 After adding ClN and stirring until completely dissolved, add 0.92 mL of SiCl4 dropwise and stir until homogeneous. The silicon deposition solution is now ready.
[0045] Electrochemical deposition: A three-electrode system was used for electrochemical deposition. The working electrode was the product of step A, the counter electrode was a graphite electrode, and the reference electrode was an Ag electrode. The electrochemical deposition voltage was -3.5V, and the deposition time was 60min.
[0046] Sample preparation after deposition: The deposited sample was washed three times sequentially with deoxygenated PC and anhydrous ethanol. It was then dried in a vacuum drying oven at 60℃ for 2 hours.
[0047] Implementation method of step C:
[0048] (1) Solution A: Weigh 40 mg PVP and dissolve it in 100 mL of deionized water. Stir magnetically until completely dissolved. Then weigh 200 mg MWCNT. S (MWCNT S The agate mortar (with a purity of 95%, a tube diameter of 10–20 nm, and a length of 10–30 μm) was ground for 30 min, dissolved in the above solution, and sonicated for 1 h.
[0049] (2) Solution B: Weigh 2 mg Al(NO3)2·9H2O and add it to 100 mL of L3H8O and stir magnetically until completely dissolved.
[0050] (3) Measure 1 mL of solution A and add it to solution B. Stir magnetically for 1 h and then sonicate for 2 h. The MWCNTs electrophoresis solution is now ready.
[0051] Electrophoretic deposition was performed using a dual-electrode system. The working electrode was the sample prepared in step B, and the counter electrode was a graphite electrode. Electrophoresis was performed at 90V for 20 minutes. After electrophoresis, the sample was allowed to air dry naturally.
[0052] The uneven edges of the prepared sample were trimmed off, and the sample was cut into a 14mm diameter disc. This disc was used as the negative electrode, a lithium sheet as the positive electrode, and LiPF6 (1M LiPF6+EC / DMC(1:1)v / v) as the electrolyte. A Clgard 2400 separator was used, and the discs were assembled into a 2032 button cell in an argon-filled glove box. The battery performance was tested with a charge / discharge voltage window of 0.01–3.0V and a rate of 0.1C.
[0053] like Figure 1 As shown in the figure, the copper electrochemically deposited using the hydrogen bubble template method has a 3D porous structure. Figure 2 As shown, silicon adheres relatively uniformly to the surface of the porous copper. (As...) Figure 3 As shown, MWCNTs are coated on the outermost layer, isolating the active silicon layer from the electrolyte, effectively avoiding side reactions caused by direct contact between silicon and electrolyte, and presenting an overall 3D porous multilayer structure.
[0054] like Figure 4 As shown in the figure, the initial capacities of the Cu / Si / MWCNTs and Cu / Si composite anodes are not significantly different. However, after 150 cycles, the Cu / Si / MWCNTs composite anode still has a reversible capacity of approximately 2500 mAh / g, while the Cu / Si composite anode only has a reversible capacity of approximately 1800 mAh / g. The Cu / Si / MWCNTs composite anode exhibits better cycle stability. The coating of MWCNTs avoids direct contact between the active material and the electrolyte, reducing the probability of active material failure due to side reactions, thus significantly improving battery capacity.
[0055] like Figure 5As shown in the figure, the Cu / Si / MWCNTs composite anode has a reversible capacity of approximately 3300 mAh / g at 0.1C and still retains approximately 2100 mAh / g at a higher rate of 10C. After 80 charge-discharge cycles at different rates, returning to 0.1C yields a reversible capacity of approximately 3100 mAh / g, indicating good material recovery performance. In contrast, the Cu / Si composite anode has a reversible capacity of approximately 3000 mAh / g at 0.1C. However, the capacity decays relatively rapidly with increasing rate, reaching only about 1600 mAh / g at 10C and only about 2500 mAh / g at 0.1C, a significant difference from the initial 0.1C capacity. This is because the high current causes the active material to expand and pulverize, resulting in irreversible damage to the composite material structure and poor recovery. The rate performance comparison demonstrates that MWCNTs coating optimizes the battery's rate performance.
Claims
1. A semi-solid lithium battery anode structure, characterized in that, This lithium-ion battery anode is composed of a composite layer consisting of a 3D porous Cu current collector framework structure, an active layer, and a carbon coating layer. The active layer is formed by layering the 3D porous Cu current collector framework structure, and the carbon coating layer is uniformly coated on the active layer. The pore size of the 3D porous Cu current collector framework structure is 10µm~100µm, the deposition mass of the active material is 0.1~1.0mg, and the thickness of the carbon coating is 0.1µm~10µm. The 3D porous Cu current collector framework structure is composed of a copper foil as a substrate and a 3D porous Cu current collector framework. The active layer is directly composited onto the 3D porous Cu current collector framework using an integrated electrochemical deposition method. The anode is a self-supporting structure. The method for preparing the semi-solid lithium battery anode structure includes: A. A 3D porous Cu current collector framework is electrochemically deposited on copper foil using a hydrogen bubble template method. The working electrode is a copper foil with a thickness of 9 μm and a diameter of 18 mm, the counter electrode is a high-purity copper sheet with a thickness of 0.1 mm, and the reference electrode is a platinum mesh electrode. B. Electrochemical deposition of active material on a 3D porous Cu current collector framework, using C4H6O as the solvent of the deposition solution, wherein the active material is silicon or germanium; including: B.1 Preparation of sedimentation solution: Measure 39.1 mL of C4H6O and weigh 1.15 g of C8H 20 After adding ClN and stirring until completely dissolved, add 0.92 mL of SiCl4 dropwise and stir until homogeneous; the silicon deposition solution is now ready. B.2 Electrochemical deposition: Electrodeposition adopts a three-electrode system. The working electrode is the product of step A, the counter electrode is a graphite electrode, and the reference electrode is an Ag electrode. The electrodeposition voltage is -3.5V and the deposition time is 60min. B.3 Sample processing after deposition: The deposited sample was washed three times with deoxygenated PC and anhydrous ethanol in sequence; then dried in a vacuum drying oven at 60℃ for 2 hours. C. Carbon material is then coated onto the surface of a 3D porous composite structure via electrophoretic deposition. The 3D porous Cu current collector framework serves as an electron transport channel, the carbon coating layer serves as an ion transport layer, and the lithium battery anode places the positive and negative charge transport conductors on the upper and lower sides of the active layer, respectively, so that the electric and ion transport in the active layer are reversed, establishing a stable and efficient charge transport mechanism.
2. The semi-solid lithium battery anode structure according to claim 1, characterized in that, Step A further includes: A.1 Copper foil pretreatment: First, ultrasonically pickle the copper foil with 10% HCl for 5 minutes to remove the surface oxide layer, and then ultrasonically clean it with acetone, anhydrous ethanol and deionized water for 3-5 minutes in sequence. A.2 Preparation of deposition solution: Weigh 2.26g CuSO4 and dissolve it in 63.1mL deionized water. Stir magnetically until completely dissolved. Weigh 8.48g NaH2PO4 and add it to the solution. Stir magnetically for 10min. Then add 5.8mL H2SO4 dropwise. Weigh 0.14mg PEG and measure 59μL HCl. Add them sequentially and stir magnetically for 10min. The porous copper deposition solution is now ready. A.3 Electrochemical Deposition: Electrodeposition employs a three-electrode system, with an electrodeposition current density of 3 A / cm². 2 The time is 10 seconds; A.4 Sample processing after deposition: Wash the deposited sample three times with deionized water and anhydrous ethanol respectively; dry it in a vacuum drying oven at 80℃ for 3 hours.
3. The semi-solid lithium battery anode structure according to claim 1, characterized in that, Step C further includes: C.1 Solution A: Weigh 40 mg PVP and dissolve it in 100 mL of deionized water. Stir magnetically until completely dissolved. Then weigh 200 mg MWCNT. S After grinding the agate in a mortar for 30 minutes, dissolve it in the above solution and sonicate for 1 hour. C.2 Solution B: Weigh 2 mg Al(NO3)2•9H2O and add it to 100 mL of C3H8O and stir magnetically until completely dissolved; C.
3. Take 1 mL of solution A and add it to solution B. Stir magnetically for 1 h and then sonicate for 2 h. The MWCNTs electrophoresis solution is now ready.
4. The semi-solid lithium battery anode structure according to claim 3, characterized in that, The MWCNT S The purity is 95%, the tube diameter is 10~20nm, and the length is 10~30µm.