Electrode material ion supplementing method

Abstract

The invention relates to an electrode material ion supplementing method, which comprises the following steps of: dissolving a metal simple substance in liquid ammonia serving as a solvent, soaking an electrode material or an electrode plate in ion supplementing liquid, and subsequently calcining to obtain a finished product electrode material or electrode plate. The method effectively improves the initial coulombic efficiency of an electrode material or an electrode plate, can be suitable for supplementing ions such as lithium, sodium, potassium and calcium in the electrode material or the electrode plate, improves the applicability of an ion supplementing method, and reduces the ion supplementing cost of the electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrode manufacturing, and in particular to a method for replenishing ions of electrode materials. Background Art

[0002] Secondary ion batteries (lithium-ion, sodium-ion, potassium-ion, etc.) have demonstrated unparalleled high energy and power density, fast charging, and long life, making this technology an excellent choice for electric vehicles, portable electronic devices, energy storage, and many other applications. In recent years, research in this field has led companies and governments to invest heavily in the development of increasingly efficient and safer batteries.

[0003] Secondary ion batteries require the nearly lossless repeated insertion and removal of ions between the positive and negative electrodes to maintain normal function, resulting in a Coulombic efficiency approaching 100%. However, both the positive and negative electrode materials undergo side reactions with ions, leading to irreversible losses and reduced Coulombic efficiency. Examples include the irreversible insertion of lithium into the ternary positive electrode and silicon-based negative electrode in lithium-ion batteries, and the irreversible insertion of sodium into the Prussian blue positive electrode and hard carbon negative electrode in sodium-ion batteries. This reduction in Coulombic efficiency reduces the actual available cycle energy density of the ion battery and shortens its cycle life.

[0004] In order to solve the problem of positive and negative electrode ion loss, pretreatment of electrode materials and electrode sheets in the manufacturing stage to reduce the occurrence of irreversible reactions is currently the most effective way to solve the problem of electrode ion loss.

[0005] Chinese patent CN 102214824 discloses a negative electrode material for a non-aqueous electrolyte secondary battery, a manufacturing method thereof, and a lithium-ion secondary battery. The process involves mixing and calcining a silicon-based negative electrode with compounds such as lithium hydride or lithium aluminum hydride, resulting in a high content of lithium within the silicon-based negative electrode before the battery electrode is formed. This process subjects the negative electrode material to high-temperature calcination, which degrades the material's properties and increases energy costs.

[0006] Chinese patent CN115642318A discloses a negative electrode lithium replenishment method, a negative electrode lithium replenishment device, a negative electrode, and a battery. The negative electrode lithium replenishment method adopts a staged lithium replenishment method. The first lithium replenishment stage can quickly replenish lithium to the negative electrode, improving the lithium replenishment efficiency of the negative electrode. The second lithium replenishment stage can accurately control the degree of lithium replenishment of the negative electrode, ensuring the uniformity of lithium replenishment and avoiding local excessive or insufficient lithium replenishment. In addition, a structurally stable SEI film is generated during the lithium replenishment process to ensure the structural stability of the negative electrode, improve the initial efficiency of the negative electrode, and effectively suppress the volume expansion of the active component layer in the negative electrode.

[0007] There are also technologies that use lithium foil, inert lithium powder, etc. to supplement lithium, but these technologies have the disadvantages of poor uniformity and safety.

[0008] Chinese patent CN116014099A discloses a positive electrode lithium replenisher, its preparation method, and application. The positive electrode lithium replenisher comprises a halogen-based lithium replenisher material and an iron-based lithium replenisher material. The particle sizes of the halogen-based lithium replenisher material and the iron-based lithium replenisher material independently satisfy the following relationship: 3 ≤ (D90 - D10) / D50 ≤ 5. By mixing the halogen-based lithium replenisher material and the iron-based lithium replenisher material that meet certain particle size requirements, a mixed positive electrode lithium replenisher is obtained. Within the specified particle size range, this mixed positive electrode lithium replenisher can improve the stability of the positive electrode slurry and increase the first-cycle charge capacity of the battery.

[0009] Chinese patent CN114242954A discloses a lithium replenishment system and method for lithium-ion battery negative electrode sheets. The lithium replenishment system for lithium-ion battery negative electrode sheets includes: an unwinding device, a lithium replenishment tank, a cleaning tank, and a winding device; one end of the negative electrode sheet to be replenished is wound on the unwinding device, and the other end passes through the lithium replenishment tank and the cleaning tank in sequence and is wound on the winding device; the lithium replenishment tank contains a lithium replenishment solution, and the cleaning tank contains a cleaning solution. This lithium replenishment system for lithium-ion battery negative electrode sheets can complete lithium replenishment of the sheet by immersing the sheet in the lithium replenishment solution in the lithium replenishment tank during the sheet feeding process, thereby embedding lithium into the negative electrode. This significantly improves the uniformity of lithium replenishment of the sheet. Subsequently, the sheet is further immersed in the cleaning solution to remove the residual lithium replenishment solution and other residues on the surface of the sheet. Therefore, the system can achieve uniform lithium replenishment of the sheet and is easy to implement large-scale production.

[0010] Chinese patent CN 107851783, "A method for manufacturing a negative electrode active material and a negative electrode for a non-aqueous electrolyte secondary battery," and a non-aqueous electrolyte secondary battery, involves immersing a silicon-based negative electrode material in a lithium-containing solution containing polycyclic aromatic compounds or their derivatives to achieve non-high-temperature liquid-phase lithium replenishment. While this method avoids high-temperature calcination, it has several drawbacks. For example, the immersion solution contains complex organic compounds, which react over time to form polycarbonates, increasing viscosity and gradually solidifying, making them difficult to remove from the material surface. Furthermore, the material surface is enriched with lithium-containing compounds, making it sensitive to air moisture and increasing material costs. Summary of the Invention

[0011] The purpose of the present invention is to provide an electrode material ion replenishment method, which effectively improves the initial coulombic efficiency of the electrode material or electrode sheet, improves the applicability of the ion replenishment method, and reduces the cost of replenishing ions of the electrode material.

[0012] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0013] A method for replenishing ions of an electrode material comprises the following steps:

[0014] 1) dissolving the metal in liquid ammonia under low temperature and / or high pressure to obtain an ion replenisher; low temperature refers to a temperature of -77°C to -34°C, and high pressure refers to a pressure of 1.1 MPa to 1.5 MPa;

[0015] 2) soaking the electrode material or electrode sheet in the ion replenishing solution under low temperature or high pressure environment and then taking it out to obtain a pretreated electrode material or electrode sheet; the low temperature refers to a temperature of -77°C to -34°C, and the high pressure refers to a pressure of 1.1 MPa to 1.5 MPa;

[0016] 3) The removed electrode material or electrode sheet is allowed to stand in dry air or inert gas for 10 seconds to 300 minutes, and then calcined at a temperature of 150 to 1800° C. under inert gas protection for 10 seconds to 300 minutes to obtain a finished electrode material or electrode sheet; the dew point temperature of the dry air is -45° C. to -30° C.;

[0017] Alternatively, the removed electrode material or electrode sheet is washed with liquid ammonia to obtain a finished electrode material or electrode sheet.

[0018] Preferably, in step 3), the electrode material or electrode sheet is washed with liquid ammonia and then calcined to obtain a finished electrode material or electrode sheet.

[0019] Preferably, the metal is one or more of lithium, sodium, potassium and calcium.

[0020] Preferably, when there are two or more metals, during the preparation of the ion replenisher, different types of metals should be completely dissolved in liquid ammonia to obtain ion replenishers containing a single metal, and then the ion replenishers should be mixed to obtain ion replenishers containing multiple metals.

[0021] Preferably, the ion supplement solution is a supersaturated solution.

[0022] Preferably, the soaking time of the electrode material is 1-10080 minutes, preferably 60-180 minutes; the soaking time of the electrode sheet is 1-1440 minutes, preferably 10-120 minutes.

[0023] Preferably, in step 2), the container for holding the ion supplement solution is electrically conductive, and preferably, the container is a stainless steel container.

[0024] Preferably, in step 2), when treating the electrode material, a voltage is applied between the container and the ion replenishing solution, the voltage range may be 0.1 to 1000 V, and the current range may be 1 μA to 10 A;

[0025] When treating the electrode sheet, a voltage is applied between the electrode sheet and the ion replenishing solution. The voltage range can be 0.1 to 1000 V, and the current range can be 1 μA to 10A.

[0026] Preferably, in step 2), stirring or ultrasonic treatment is performed during the soaking process.

[0027] The present invention uses liquid ammonia as a solvent, and metals such as lithium, sodium, potassium, and calcium are dissolved in liquid ammonia to form metal electrons containing ammonia ions. Depending on the different supplementary ion materials, under the action of concentration diffusion, ion diffusion driven by reaction barriers, potential difference driven reactions, and external electric field driven reactions, the ammonia ions in the metal electrons containing ammonia ions in the solution dissociate, and the metal ions enter the interior of the material to complete the ion supplementation of the electrode material or electrode sheet. Liquid ammonia can be obtained by lowering the temperature or increasing the pressure, or by lowering the temperature and increasing the pressure at the same time, as long as the temperature and pressure conditions of ammonia are within the liquid region of its three-phase diagram. Preferably, when using the temperature reduction method, the temperature range is -77°C to -34°C, and when using the pressure increase method, the pressure is 1.1MPa to 1.5MPa.

[0028] The use of liquid ammonia as a solvent has the following advantages over the traditional use of organic solvents as solvents:

[0029] (1) Low raw material cost. Ammonia is a cheap industrial raw material with a unit price much lower than that of organic solvents.

[0030] (2) Reusable. If the prepared liquid ammonia solution cannot be used due to reasons such as being stored for too long or being accidentally contaminated, it does not need to be discarded. Pure gaseous ammonia can be simply separated by heating and reducing pressure and collected and reused. The original solute will also precipitate due to the evaporation of the solvent and re-form the corresponding solid substance.

[0031] (3) No side reactions. There are no side reactions in liquid ammonia solution, while organic solvents will undergo side reactions such as ring opening and polymerization under the catalysis of metal ions, which will increase the impurities and solution viscosity, reduce the treatment effect, and slowly turn into gel and solid over time. The lifespan is usually within 3 days, and it depends on being prepared and used immediately.

[0032] (4) No residue. The electrode material or electrode sheet treated with liquid ammonia can volatilize and remove the small amount of residual ammonia at room temperature and pressure, while organic solvents are difficult to volatilize, and the carbon impurities in them will adhere to the surface of the material and cannot be removed.

[0033] The present invention can simultaneously replenish one or more of the lithium ions, sodium ions, potassium ions, and calcium ions in the electrode material. When it is necessary to replenish two or more metal ions at the same time, when preparing the ion replenishing solution, it is necessary to completely dissolve the single metal in liquid ammonia to form an ion replenishing solution containing the single metal, and then mix the ion replenishing solution containing the single metal to prepare an ion replenishing solution containing multiple metals. Otherwise, when multiple metals are dissolved in liquid ammonia at the same time, intermetallic compounds or alloys are easily formed between the multiple metal elements, which brings additional process difficulty and danger to the preparation of the ion replenishing solution. During the dissolution of the metal element, stirring and ultrasonic methods can be used to accelerate the dissolution of the metal element.

[0034] The ion supplement used is preferably a supersaturated solution, mainly for the following reasons:

[0035] 1. The supersaturated solution can ensure that the liquid ammonia solution reaches the upper limit of ion concentration, which is beneficial to accelerate the replenishment of ions through concentration diffusion when the electrode material or electrode sheet is immersed in the ion replenishment solution.

[0036] 2. Insoluble metal elements remain in the supersaturated solution. After the ions in the ion replenisher diffuse into the electrode material or electrode sheet, the ions in the ion replenisher can be replenished in time.

[0037] 3. The presence of insoluble metal elements in the supersaturated solution will change the electrochemical potential of the system and promote the diffusion of ions into the electrode material or electrode sheet.

[0038] 4. The conductivity of the supersaturated solution is significantly higher than that of the corresponding unsaturated solution, which is conducive to the electron exchange in the ion replenishment process.

[0039] The ion replenisher can be reused, and metal elements should be added to the ion replenisher in time. Otherwise, as the processing volume of electrode materials or electrode sheets increases, the ion concentration in the ion replenisher will gradually decrease, and the color will fade and become transparent, and the ion replenishment effect will deteriorate.

[0040] If the ion replenisher is left for a long time (>30 days), a small amount of amide impurities will be generated, which will have an adverse effect on the performance of the finished product. When using ion replenisher that has been prepared for more than 30 days to replenish ions on electrode materials or electrode sheets, the electrode materials or electrode sheets should be washed with liquid ammonia at least twice to thoroughly clean the small amount of amide generated in the solution and avoid the attachment of amide impurities on the surface of the electrode materials or electrode sheets, which will affect the electrode performance.

[0041] The electrode material or electrode sheet is taken out of the ion replenishing liquid and separated from the high-pressure or low-temperature environment required to form liquid ammonia. The liquid ammonia containing metal elements remaining on the surface of the electrode material or electrode sheet is volatilized, and crystals with metal amide as the main component are formed on the surface of the electrode material or electrode sheet, which have an adverse effect on the use of the electrode material or electrode sheet. Subsequent calcination can, on the one hand, remove the amide remaining on the surface or inside of the electrode material or electrode sheet; on the other hand, calcination can enable the replenished metal ions to form chemical bonds with the electrode material or electrode sheet, thereby preventing the replenished ions from being in a highly active state and being lost or inactivated due to contact with water during subsequent processing.

[0042] After removing the electrode material or electrode sheet from the ion replenisher, it should be washed with liquid ammonia as soon as possible. During the washing process, the ambient temperature and pressure must be controlled to ensure that the residual liquid ammonia on the surface of the electrode material or electrode sheet does not vaporize rapidly. After washing with liquid ammonia, the finished electrode material or electrode sheet can be obtained directly or after calcination.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1) The present invention uses liquid ammonia as a solvent and directly uses a metal element dissolved in liquid ammonia to form an ion replenishing liquid to replenish ions in the electrode material or electrode sheet, effectively improving the initial coulombic efficiency of the electrode material or electrode sheet. It has a wide range of applications and can be simultaneously applied to replenishing lithium, sodium, potassium, calcium, and other ions in the electrode material or electrode sheet. Compared with the traditional use of organic solvents as solvents for replenishing ions in electrode materials or electrode sheets, the cost is low, the environmental pollution is small, and the subsequent processing is simple. In addition, the applicability of organic solvents is generally more targeted and cannot be applied to replenish all metal ions.

[0045] 2) The treatment process of the present invention is controllable, has simple steps, can be matched with existing electrode materials and electrode sheet manufacturing process flows, and is used to effectively solve the element deficiency problem of ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the first charge-discharge curve of the material in Example 1 of the present invention before being treated with ion replenishment technology.

[0047] Figure 2 This is the first charge-discharge curve of the material of Example 1 of the present invention after being treated with ion replenishment technology. DETAILED DESCRIPTION

[0048] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0049] Example 1

[0050] A low-temperature constant temperature bath with ultrasonic oscillation function was placed in an argon-filled glove box. 1000 mL of liquid ammonia was injected into the constant temperature bath at -35°C. 45 g of metallic lithium was added and the ultrasonic oscillation function was turned on to promote lithium dissolution. After ultrasonic oscillation until the metallic lithium was completely dissolved, 45 g of metallic lithium was added again and the ultrasonic oscillation was turned off to obtain an ion replenisher.

[0051] Take 100 g of silicon monoxide electrode material (median particle size 7 μm) and place it in a cage made of 2500 mesh stainless steel gauze. Place it in a constant temperature bath so that the silicon monoxide electrode material is completely immersed in the ion replenisher. After soaking for 4 hours, remove the stainless steel gauze and transfer it to another -35°C constant temperature bath with ultrasonic oscillation function containing 1000 mL of liquid ammonia. Soak for 180 seconds and then take it out.

[0052] The treated silicon monoxide electrode material is quickly dried after leaving the low-temperature environment, filled into a stainless steel crucible and calcined in an argon atmosphere at 500° C. for 1 hour to obtain a finished silicon monoxide electrode material.

[0053] Example 2

[0054] A low-temperature constant temperature bath with ultrasonic oscillation function was placed in an argon-filled glove box. 1000 mL of liquid ammonia was injected into the constant temperature bath at -42°C. 45 g of metallic lithium was added and the ultrasonic oscillation function was turned on to promote lithium dissolution. After ultrasonic oscillation until the metallic lithium was completely dissolved, 45 g of metallic lithium was added again and the ultrasonic oscillation was turned off to obtain an ion replenisher.

[0055] Take 100g of micron silicon electrode material (median particle size 10 microns) and place it in a cage made of 2500 mesh stainless steel mesh. Place it in a constant temperature bath so that the micron silicon electrode material is completely immersed in the ion replenisher. After soaking for 4 hours, take out the stainless steel mesh and transfer it to another -35℃ constant temperature bath with ultrasonic oscillation function containing 1000mL liquid ammonia. Soak for 180 seconds and then take it out.

[0056] The processed micron silicon electrode material is quickly dried after leaving the low-temperature environment, filled into a stainless steel crucible and calcined in an argon atmosphere at 200° C. for 1 hour to obtain a finished silicon electrode material.

[0057] Example 3

[0058] A low-temperature constant temperature bath with ultrasonic oscillation function was placed in an argon-filled glove box. 1000 mL of liquid ammonia was injected into the constant temperature bath at -60°C. 45 g of metallic lithium was added and the ultrasonic oscillation function was turned on to promote lithium dissolution. After ultrasonic oscillation until the metallic lithium was completely dissolved, 45 g of metallic lithium was added again and the ultrasonic oscillation was turned off to obtain an ion replenisher.

[0059] Take 8g of silicon monoxide electrode material, disperse it with 1g of Super P conductive carbon black, 0.5g of CMC binder, and 0.5g of SBR binder in 50mL of water to form a slurry, apply it on copper foil and dry it. Control the coating amount so that the surface loading is about 10mg / cm 2 , and obtain a silicon monoxide electrode sheet.

[0060] Cut a 10cm*10cm silicon monoxide electrode sheet and clamp it with a positive electrode clamp so that the silicon monoxide electrode sheet is completely immersed in the ion replenishing solution. Place the negative electrode connected to the positive electrode clamp circuit in liquid ammonia, adjust the supply voltage so that the voltage on the positive and negative electrode clamps is 2.0V, soak for 15 minutes, take it out, transfer it to another -35℃ constant temperature bath containing 1000mL liquid ammonia, soak for 60 minutes, and then take it out.

[0061] The silicon monoxide electrode sheet is quickly dried after leaving the low-temperature environment, placed in a vacuum oven and baked at 120 degrees for 1 hour, and then taken out to obtain a finished electrode sheet.

[0062] Example 4

[0063] A low-temperature constant temperature bath with ultrasonic oscillation function was placed in an argon-filled glove box. 1000 mL of liquid ammonia was injected into the constant temperature bath at -72°C. 45 g of metallic lithium was added and the ultrasonic oscillation function was turned on to promote lithium dissolution. After ultrasonic oscillation until the metallic lithium was completely dissolved, 45 g of metallic lithium was added again and the ultrasonic oscillation was turned off to obtain an ion replenisher.

[0064] Take 8g of NCA ternary electrode material, 1g of Super P conductive carbon black, and 1g of PVDF binder and disperse them in 50mL of NMP to form a slurry. Apply it on aluminum foil and dry it. Control the coating amount so that the surface loading is about 25mg / cm 2 , and obtain NCA ternary electrode sheet.

[0065] Cut a 10cm*10cm NCA ternary electrode sheet and clamp it with a positive electrode clamp so that the NCA ternary electrode sheet is completely immersed in the ion replenishing solution. Place the negative electrode connected to the positive electrode clamp circuit in liquid ammonia, adjust the supply voltage so that the voltage on the positive and negative electrode clamps is 5.1V, soak for 10 minutes, take it out, transfer it to another -35℃ constant temperature bath containing 1000mL liquid ammonia, soak for 30 minutes, and then take it out.

[0066] The NCA ternary electrode sheet is quickly dried after leaving the low-temperature environment, placed in a vacuum oven and baked at 140 degrees for 1 hour, and then taken out to obtain the finished electrode sheet.

[0067] Example 5

[0068] A low-temperature constant temperature bath with ultrasonic oscillation function was placed in an argon-filled glove box. 1000 mL of liquid ammonia was injected into the constant temperature bath at -54°C. 15 g of metallic sodium was added and the ultrasonic oscillation function was turned on to promote the dissolution of the sodium. After ultrasonic oscillation until the metallic sodium was completely dissolved, 15 g of metallic sodium was added again and the ultrasonic oscillation was turned off to obtain an ion replenisher.

[0069] Take 100g of hard carbon electrode material (median particle size 10 microns) and place it in a cage made of 2000 mesh stainless steel mesh. Place it in a constant temperature bath so that the hard carbon electrode material is completely immersed in liquid ammonia. After soaking for 1 hour, take out the stainless steel mesh. The treated hard carbon electrode material dries quickly after leaving the low-temperature environment, and white powdery crystals appear on the surface. Fill the treated hard carbon electrode material into a stainless steel crucible and calcine it in an argon atmosphere at 800°C for 1 hour to obtain the finished hard carbon electrode material.

[0070] Example 6

[0071] A low-temperature constant temperature bath with ultrasonic oscillation function is placed in an argon-filled glove box, 1000 mL of liquid ammonia is injected into the constant temperature bath at -63°C, 15 g of metallic sodium is added, and the ultrasonic oscillation function is turned on to promote the dissolution of sodium, thereby obtaining an ion replenisher containing sodium; 1000 mL of liquid ammonia is injected into another constant temperature bath at -35°C, 45 g of metallic lithium is added, and the ultrasonic oscillation function is turned on to promote the dissolution of lithium, thereby obtaining an ion replenisher containing lithium; the sodium-containing ion replenisher and the lithium-containing ion replenisher are mixed into another constant temperature bath at -35°C and the ultrasonic oscillation is turned off to obtain an ion replenisher containing both sodium and lithium.

[0072] Take 100g of hard carbon electrode material (median particle size 10 microns) and place it in a cage made of 2000 mesh stainless steel gauze. Place it in a constant temperature bath so that the hard carbon electrode material is completely immersed in the ion replenisher. After soaking for 100 minutes, take out the stainless steel gauze. The treated hard carbon electrode material is quickly dried after leaving the low-temperature environment, and white powdery crystals appear on the surface. Fill the treated hard carbon electrode material into a stainless steel crucible and calcine it in an argon atmosphere at 800°C for 1 hour to obtain the finished hard carbon electrode material.

[0073] Example 7

[0074] A low-temperature constant temperature bath with ultrasonic oscillation function was placed in a glove box filled with argon. 1000 mL of liquid ammonia was injected into the constant temperature bath at -77°C. 45 g of metallic lithium was added and the ultrasonic oscillation function was turned on to promote lithium dissolution. After complete dissolution, the ultrasonic oscillation was turned off to obtain an ion replenisher.

[0075] 100 g of silicon monoxide electrode material (median particle size 7 μm) was placed in a cage made of 2500 mesh stainless steel gauze, and then placed in a constant temperature bath so that the silicon monoxide electrode material was completely immersed in the ion replenisher. After soaking for 8 hours, the stainless steel gauze was removed and transferred to another -35°C constant temperature bath with ultrasonic oscillation function containing 1000 mL of liquid ammonia, and soaked for 246 minutes before being taken out. The treated silicon monoxide electrode material was quickly dried after leaving the low-temperature environment, filled in a stainless steel crucible, and calcined in an argon atmosphere at 500°C for 1 hour to obtain a finished silicon monoxide electrode material.

[0076] Example 8

[0077] A low-temperature thermostatic bath with an ultrasonic oscillation function was placed in an argon-filled glove box. 1000 mL of liquid ammonia was injected into thermostatic bath A at -46°C, 15 g of metallic sodium was added, and the ultrasonic oscillation function was turned on to promote metal dissolution. 1000 mL of liquid ammonia was injected into thermostatic bath B at -45°C, 45 g of metallic lithium was added, and the ultrasonic oscillation function was turned on to promote metal dissolution. 1000 mL of liquid ammonia was injected into thermostatic bath C at -35°C, 5 g of metallic potassium was added, and the ultrasonic oscillation function was turned on to promote metal dissolution. 1000 mL of liquid ammonia was injected into thermostatic bath D at -35°C, 5 g of metallic calcium was added, and the ultrasonic oscillation function was turned on to promote metal dissolution. The liquid ammonia solutions in thermostatic baths A, B, C, and D were drained and mixed into another thermostatic bath at -35°C, and the ultrasonic oscillation was turned off to obtain an ion supplement solution containing sodium, lithium, potassium, and calcium.

[0078] 100 g of hard carbon electrode material (median particle size 10 μm) was placed in a cage made of 2000 mesh stainless steel gauze, and placed in a constant temperature bath to completely immerse the hard carbon electrode material in the ion replenisher solution. After soaking for 180 minutes, the stainless steel gauze was removed and transferred to a sealed stainless steel tube at -35°C and allowed to stand for 2 hours. A vacuum pump was used to maintain the pressure in the sealed stainless steel tube at 10 -3 The obtained hard carbon electrode material, which had a metallic luster on its surface, was taken out as powdery crystals. The processed hard carbon electrode material was placed in a stainless steel crucible and calcined at 800° C. in an argon atmosphere for 1 hour to obtain a finished hard carbon electrode material.

[0079] 0.8 g of the electrode materials obtained in Examples 1, 2, 5, 6, 7, and 8 were respectively taken and dispersed together with 0.06 g of single-walled carbon nanotubes, 0.04 g of CMC binder, and 0.1 g of SBR binder in 5 mL of water to form a uniform slurry, which was then coated on copper foil to form an electrode sheet. The obtained electrode sheet and the electrode sheet obtained in Examples 3 and 4 were vacuum dried and then punched into circular electrode sheets.

[0080] Examples 1 to 4 use metallic lithium as the counter electrode, Examples 5 and 6 use metallic sodium as the counter electrode, 1 mol / L LiPF6 / DMC+DEC+EC (volume ratio of 1:1:1) is the electrolyte for Examples 1-4, 1 mol / L NaPF6 / PC+EC (volume ratio of 1:1) is the electrolyte for Examples 5 and 6, Celgard2400 is the diaphragm for Examples 1-4, and PAN-based nanofiber membrane is the diaphragm for Examples 5 and 6, forming the experimental battery.

[0081] The battery was subjected to a 0.1C constant current charge and discharge test (1C=1500mAh / g). The first coulombic efficiency of the embodiment at different charge and discharge voltages is shown in Table 1.

[0082] It can be seen from Table 1 that after the electrode material or electrode sheet is supplemented with ions using the method of the present invention, the first coulombic efficiency is significantly improved.

[0083] Figure 1 and Figure 2 1 and 2 are the first charge and discharge curves of the electrode material before and after ion replenishment according to Example 1 of the present invention. As can be seen from the figure, the first coulombic efficiency is significantly improved after the electrode material is replenished with ions.

[0084] Table 1

[0085]

[0086]

Claims

1. A method for replenishing ions of electrode materials, characterized in that: The steps include: 1) dissolving the metal in liquid ammonia under low temperature and / or high pressure to obtain an ion replenisher; low temperature refers to a temperature of -77°C to -34°C, and high pressure refers to a pressure of 1.1 MPa to 1.5 MPa; 2) soaking the electrode material or electrode sheet in the ion replenishing solution under low temperature or high pressure environment and then taking it out to obtain a pretreated electrode material or electrode sheet; the low temperature refers to a temperature of -77°C to -34°C, and the high pressure refers to a pressure of 1.1 MPa to 1.5 MPa; 3) The removed electrode material or electrode sheet is allowed to stand in dry air or inert gas for 10 seconds to 300 minutes, and then calcined in an inert atmosphere to obtain a finished electrode material or electrode sheet; The dew point temperature of the dry air is -45°C to -30°C; Alternatively, the removed electrode material or electrode sheet is washed with liquid ammonia to obtain a finished electrode material or electrode sheet.

2. The electrode material ion replenishing method according to claim 1, wherein: In step 3), the electrode material or electrode sheet is washed with liquid ammonia and then calcined to obtain a finished electrode material or electrode sheet.

3. The electrode material ion replenishing method according to claim 1 or 2, characterized in that: The calcination temperature is 150-1800° C., and the calcination time is 10 seconds-300 minutes.

4. The electrode material ion replenishing method according to claim 1, wherein: The metal is one or more of lithium, sodium, potassium and calcium.

5. The electrode material ion replenishing method according to claim 4, characterized in that: When there are two or more metals, during the preparation of the ion replenisher, different types of metals should be completely dissolved in liquid ammonia to obtain ion replenishers containing a single metal, and then the ion replenishers should be mixed to obtain ion replenishers containing multiple metals.

6. The electrode material ion replenishing method according to claim 1, wherein: The ion supplement solution is a supersaturated solution.

7. The electrode material ion replenishing method according to claim 1, wherein: In step 2), the soaking time of the electrode material is 1-10080 minutes, preferably 60-180 minutes; the soaking time of the electrode sheet is 1-1440 minutes, preferably 10-120 minutes.

8. The electrode material ion replenishing method according to claim 1 or 7, characterized in that: In step 2), the container for containing the ion supplement solution is electrically conductive, and preferably, the container is a stainless steel container.

9. The electrode material ion replenishing method according to claim 7 or 8, characterized in that: In step 2), when treating the electrode material, a voltage is applied between the container and the ion replenishing solution, the voltage range may be 0.1 to 1000 V, and the current range may be 1 μA to 10 A; When treating the electrode sheet, a voltage is applied between the electrode sheet and the ion replenishing solution. The voltage range can be 0.1 to 1000 V, and the current range can be 1 μA to 10A.

10. The electrode material ion replenishing method according to claim 1, 7 or 8, characterized in that: In step 2), stirring or ultrasonic treatment is performed during the soaking process.

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