Transition metal-doped cupric oxide nanomaterial, preparation method thereof, negative plate and battery

Abstract

The embodiment of the present application relates to transition metal doped copper cobaltate nanomaterial and a preparation method thereof, a negative plate and a battery, and belongs to the technical field of lithium ion battery negative materials.The embodiment of the present application aims to solve the technical problems of low intrinsic electronic conductivity and low lithium ion migration driving force of copper cobaltate as a negative material in the prior art.The transition metal doped copper cobaltate nanomaterial of the embodiment of the present application has a chemical molecular formula of Cu 1‑x M x Co2O4, wherein M represents a transition metal, and the value range of x is 0.05 <= x <= 0.1.The material provided in the embodiment of the present application exhibits excellent electrochemical performance and excellent cycle stability through the doping of a transition metal element.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery anode material technology, and particularly to a transition metal-doped copper cobalt oxide nanomaterial, its preparation method, anode sheet, and battery. Background Technology

[0002] For decades, lithium-ion batteries (LIBs) have been considered promising energy storage devices, widely used in our lives due to their high safety, high energy density, good cycle performance, and environmental friendliness. They have shown great potential in large-scale applications, including hybrid vehicles, portable electronic devices, and stationary energy storage. However, some obstacles still affect the development of lithium-ion batteries, such as the limited capacity of anode materials. As a crucial component of lithium-ion batteries, the anode is critical to battery performance. Graphite is the most commercially available anode, but its theoretical capacity is limited (372 mAh g⁻¹). -1 The existing anode materials cannot meet the growing demands of rapid societal development. To address this issue, exploring new anode materials has become an urgent task. Researchers worldwide have conducted extensive studies and found that transition metal oxides (TMOs) are being studied extensively among many anode materials due to their high theoretical capacity, potentially replacing graphene-based materials. Examples include Co3O4, CuO, Mn2O3, Fe2O3, and ZnO. Binary metal oxides (BMOs), as transition metal oxides, such as CuCo2O4, ZnCo2O4, NiCo2O4, and ZnMn2O4, exhibit excellent electrochemical performance due to their synergistic effects and complex chemical compositions. Among various BMOs, spin-structured CuCo2O4 stands out due to its high theoretical capacity (872 mAh g / g). -1 CuCo2O4 is considered a promising candidate anode material due to its environmental friendliness. However, it suffers from low intrinsic electronic conductivity and low lithium-ion migration kinetics. Summary of the Invention

[0003] In view of this, embodiments of this application provide a transition metal-doped copper cobalt oxide nanomaterial, its preparation method, a negative electrode sheet, and a battery, to solve the technical problems of low intrinsic electronic conductivity and low lithium-ion migration kinetics of copper cobalt oxide in the prior art.

[0004] The first aspect of this application provides a transition metal-doped copper cobalt oxide nanomaterial, wherein the chemical formula of the transition metal-doped copper cobalt oxide nanomaterial is: Cu 1-x M x Co2O4, where M represents a transition metal and x takes values ​​in the range of 0.05 ≤ x ≤ 0.1.

[0005] In some embodiments that may include the above embodiments, the transition metal is Bi or Cr;

[0006] The transition metal is Bi, and x takes a value of 0.05;

[0007] The transition metal is Cr, and x takes the value 0.1.

[0008] A second aspect of this application also provides a method for preparing transition metal-doped copper cobalt oxide nanomaterials, comprising the following steps:

[0009] Step 1: Weigh out the copper source, cobalt source, transition metal source and precipitant according to the stoichiometric ratio of the chemical formula of the transition metal-doped copper cobalt oxide nanomaterial, dissolve them in an appropriate amount of organic solvent, stir evenly to obtain a mixed solution;

[0010] Step 2: The mixed solution is subjected to hydrothermal treatment to obtain an intermediate substance;

[0011] Step 3: Calcine the intermediate material to obtain transition metal-doped copper cobalt oxide nanomaterials.

[0012] In some embodiments that may include the above embodiments, the following steps are specifically included:

[0013] Step 1: Weigh (1-x) mmol of copper source, 2 mmol of cobalt source and x mmol of transition metal source according to the stoichiometric ratio of the chemical formula of the transition metal-doped copper cobalt oxide nanomaterial, dissolve them in 60-x mL of organic solvent, then add 6.67 mmol of precipitant, stir and mix evenly under a magnetic stirrer at 200 rpm, and sonicate to obtain a mixed solution.

[0014] Step 2: Place the mixed solution into a reaction vessel for hydrothermal reaction at a temperature of 140°C for 10 hours to obtain a precipitate, which is then washed and dried to obtain an intermediate substance.

[0015] Step 3: Calcine the intermediate material in air at a temperature of 450-650℃ for 2 hours to obtain transition metal-doped copper cobalt oxide nanomaterials.

[0016] In some embodiments that may include the above embodiments, the copper source is one or more of copper nitrate trihydrate, copper nitrate hexahydrate, copper sulfate, and copper chloride.

[0017] In some embodiments that may include the above embodiments, the cobalt source is one or more of cobalt nitrate hexahydrate, cobalt sulfate heptahydrate, cobalt chloride, and cobalt tetroxide.

[0018] In some embodiments that may include the above embodiments, the transition metal source is a bismuth source and / or a chromium source;

[0019] The bismuth source is one or more of bismuth nitrate, bismuth trichloride, and bismuth citrate.

[0020] The chromium source is one or more of chromium nitrate, chromium trioxide, and basic chromium sulfate.

[0021] In some embodiments that may include the above embodiments, the organic solvent is one or more of N,N-dimethylformamide, ethanol, and acetone; the precipitant is urea and / or polyacrylamide.

[0022] A third aspect of this application also provides a negative electrode sheet containing the above-described nanomaterials or nanomaterials prepared by the above-described methods.

[0023] The fourth aspect of this application also provides a battery, including the negative electrode sheet described above, and further including a battery casing, a positive electrode sheet, a separator, and an electrolyte.

[0024] Compared with the prior art, the embodiments of this application have the following beneficial effects:

[0025] 1. This application incorporates a precipitant, which utilizes a solvothermal method to improve the ionic conductivity of transition metal-doped copper cobalt oxide nanomaterials as lithium-ion battery electrode materials; the precipitant decomposes when dissolved in an organic solvent under high temperature and high pressure, causing metal ions to aggregate and form a precipitate.

[0026] 2. This application prepares transition metal-doped copper cobalt oxide by a hydrothermal method. The preparation method is simple, easy to implement, highly reproducible, reduces energy consumption, and has a high raw material utilization rate. It can prepare high-purity transition metal-doped copper cobalt oxide materials with excellent crystallinity and electrochemical performance. The materials exhibit excellent electrochemical performance and excellent cycle stability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 Cu, as described in Embodiment 1 of this application 0.95 Bi 0.05 Charge-discharge cycle diagram of Co2O4 nanomaterials;

[0029] Figure 2 Cu, as described in Embodiment 1 of this application 0.95 Bi 0.05Charge-discharge cycle diagram of Co2O4 nanomaterials;

[0030] Figure 3 Cu of Embodiment 2 of this application 0.9 Cr 0.1 Charge-discharge cycle diagram of Co2O4 nanomaterials;

[0031] Figure 4 Cu, as described in Embodiment 2 of this application 0.9 Cr 0.1 Charge-discharge cycle diagram of Co2O4 nanomaterials;

[0032] Figure 5 This is a charge-discharge cycle diagram of the CuCo2O4 nanomaterial of Comparative Example 1 of this application;

[0033] Figure 6 This is a charge-discharge cycle diagram of CuCo2O4 nanomaterials in Comparative Example 1 of this application;

[0034] Figure 7 Cu, as an embodiment of this application 0.95 Bi 0.05 Co2O4 nanomaterials, Cu 0.9 Cr 0.1 XRD spectra of Co2O4 nanomaterials and CuCo2O4 nanomaterials;

[0035] Figure 8 Here is a SEM image of the Bi-doped copper cobalt oxide nanomaterial from an embodiment of this application;

[0036] Figure 9 Here is a SEM image of the Cr-doped copper cobalt oxide nanomaterial from an embodiment of this application;

[0037] Figure 10 The image shows the CV diagram of the Bi-doped copper cobalt oxide nanomaterial according to an embodiment of this application.

[0038] Figure 11 The image shows the CV diagram of the Cr-doped copper cobalt oxide nanomaterial according to an embodiment of this application.

[0039] Figure 12 The CV diagram of CuCo2O4 nanomaterials in Comparative Example 1 of this application is shown.

[0040] Figure 13 The impedance diagram is shown for the transition metal-doped copper cobalt oxide nanomaterials of this application embodiment. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] To address the technical problems of low intrinsic electronic conductivity and low lithium-ion migration kinetics in copper cobalt oxide as an anode material in the prior art, this application presents a material with excellent electrochemical performance, exhibiting superior electrochemical performance and excellent cycle stability in electrochemical tests.

[0043] Experimental methods not specifically described in the following examples are generally performed according to national standards; if no corresponding national standard exists, they are performed according to generally accepted international standards or standards known in the art. Unless otherwise stated, all parts are parts by weight and all percentages are weight percentages.

[0044] Comparative Example 1

[0045] 0.002 mmol of copper nitrate, 0.004 mmol of cobalt nitrate, and 0.0133 mmol of urea were added to 60 ml of N,N-dimethylformamide and stirred magnetically for 0.5 h, followed by sonication for 3 minutes to ensure complete dissolution of the substances in the solvent, resulting in a mixed solution. The mixed solution was then placed in a reaction vessel for high-temperature and high-pressure reaction. The reaction vessel was placed in a forced-air drying oven, and the temperature was set at 140 °C for 10 h. The resulting precipitate was then washed three times with N,N-dimethylformamide and dried again in a forced-air drying oven at 80 °C for 20 h to obtain an intermediate powder.

[0046] The obtained intermediate powder was sintered in a muffle furnace at 550°C in air for 2 hours with a heating rate of 5°C / min. After cooling, copper cobalt oxide material, abbreviated as CuCo2O4 pure sample, was obtained.

[0047] Example 1

[0048] 0.0019 mmol of copper nitrate, 0.004 mmol of cobalt nitrate, 0.0001 mmol of bismuth nitrate, and 0.0133 mmol of urea were added to 60 ml of N,N-dimethylformamide and stirred magnetically for 0.5 h, followed by sonication for 3 minutes to ensure complete dissolution of the substances in the solvent, resulting in a mixed solution. The mixed solution was then placed in a reaction vessel for high-temperature and high-pressure reaction. The reaction vessel was placed in a forced-air drying oven, and the temperature was set at 140 °C for 10 h. The resulting precipitate was then washed three times with N,N-dimethylformamide and dried again in a forced-air drying oven at 80 °C for 20 h to obtain an intermediate powder.

[0049] The obtained intermediate powder was sintered in a muffle furnace at 550℃ in air for 2 hours, with a heating rate of 5℃ / min. After cooling, bismuth-doped copper cobalt oxide material, abbreviated as Cu, was obtained. 0.95 Bi 0.05 Co2O4 doped material.

[0050] Example 2

[0051] 0.0018 mmol of copper nitrate, 0.004 mmol of cobalt nitrate, 0.0002 mmol of chromium nitrate, and 0.0133 mmol of urea were added to 60 ml of N,N-dimethylformamide and stirred magnetically for 0.5 h, followed by sonication for 3 minutes to ensure complete dissolution of the substances in the solvent, resulting in a mixed solution. The mixed solution was then placed in a reaction vessel for high-temperature and high-pressure reaction. The reaction vessel was placed in a forced-air drying oven, and the temperature was set at 140 °C for 10 h. The resulting precipitate was then washed three times with N,N-dimethylformamide and dried again in a forced-air drying oven at 80 °C for 20 h to obtain an intermediate powder.

[0052] The obtained intermediate powder was sintered in a muffle furnace at 550℃ in air for 2 hours, with a heating rate of 5℃ / min. After cooling, chromium-doped copper cobalt oxide material was obtained, abbreviated as Cu. 0.9 Cr 0.1 Co2O4 doped material.

[0053] Example 3

[0054] 0.0019 mmol of copper nitrate, 0.004 mmol of cobalt nitrate, 0.0001 mmol of bismuth nitrate, and 0.0133 mmol of urea were added to 60 ml of N,N-dimethylformamide and stirred magnetically for 0.5 h, followed by sonication for 3 minutes to ensure complete dissolution of the substances in the solvent, resulting in a mixed solution. The mixed solution was then placed in a reaction vessel for high-temperature and high-pressure reaction. The reaction vessel was placed in a forced-air drying oven, and the temperature was set at 140 °C for 10 h. The resulting precipitate was then washed three times with N,N-dimethylformamide and dried again in a forced-air drying oven at 80 °C for 20 h to obtain an intermediate powder.

[0055] The obtained intermediate powder was sintered in a muffle furnace at 450°C in air for 2 hours with a heating rate of 5°C / min. After cooling, bismuth-doped copper cobalt oxide material was obtained, abbreviated as CuCo2O4-5%bismuth-450°C doped material.

[0056] Example 4

[0057] 0.0019 mmol of copper nitrate, 0.004 mmol of cobalt nitrate, 0.0001 mmol of bismuth nitrate, and 0.0133 mmol of urea were added to 60 ml of N,N-dimethylformamide and stirred magnetically for 0.5 h, followed by sonication for 3 minutes to ensure complete dissolution of the substances in the solvent, resulting in a mixed solution. The mixed solution was then placed in a reaction vessel for high-temperature and high-pressure reaction. The reaction vessel was placed in a forced-air drying oven, and the temperature was set at 140 °C for 10 h. The resulting precipitate was then washed three times with N,N-dimethylformamide and dried again in a forced-air drying oven at 80 °C for 20 h to obtain an intermediate powder.

[0058] The obtained intermediate powder was sintered in a muffle furnace at 650℃ in air for 2 hours with a heating rate of 5℃ / min. After cooling, bismuth-doped copper cobalt oxide material was obtained, abbreviated as CuCo2O4-5% bismuth-650℃ doped material.

[0059] Example 5

[0060] 0.0018 mmol of copper nitrate, 0.004 mmol of cobalt nitrate, 0.0002 mmol of chromium nitrate, and 0.0133 mmol of urea were added to 60 ml of N,N-dimethylformamide and stirred magnetically for 0.5 h, followed by sonication for 3 minutes to ensure complete dissolution of the substances in the solvent, resulting in a mixed solution. The mixed solution was then placed in a reaction vessel for high-temperature and high-pressure reaction. The reaction vessel was placed in a forced-air drying oven, and the temperature was set at 140 °C for 10 h. The resulting precipitate was then washed three times with N,N-dimethylformamide and dried again in a forced-air drying oven at 80 °C for 20 h to obtain an intermediate powder.

[0061] The obtained intermediate powder was sintered in a muffle furnace at 450°C in air for 2 hours with a heating rate of 5°C / min. After cooling, chromium-doped copper cobalt oxide material was obtained, abbreviated as CuCo2O4-10%chromium-450°C doped material.

[0062] Example 6

[0063] 0.0018 mmol of copper nitrate, 0.004 mmol of cobalt nitrate, 0.0002 mmol of chromium nitrate, and 0.0133 mmol of urea were added to 60 ml of N,N-dimethylformamide and stirred magnetically for 0.5 h, followed by sonication for 3 minutes to ensure complete dissolution of the substances in the solvent, resulting in a mixed solution. The mixed solution was then placed in a reaction vessel for high-temperature and high-pressure reaction. The reaction vessel was placed in a forced-air drying oven, and the temperature was set at 140 °C for 10 h. The resulting precipitate was then washed three times with N,N-dimethylformamide and dried again in a forced-air drying oven at 80 °C for 20 h to obtain an intermediate powder.

[0064] The obtained intermediate powder was sintered in a muffle furnace at 650℃ in air for 2 hours with a heating rate of 5℃ / min. After cooling, chromium-doped copper cobalt oxide material was obtained, abbreviated as CuCo2O4-10%chromium-650℃ doped material.

[0065] Example 7

[0066] XRD test

[0067] The materials prepared in Comparative Example 1, Example 1, and Example 2 were subjected to XRD tests, and the test results are as follows: Figure 7 As shown. From Figure 7 It can be observed that no characteristic peaks of chromium oxide and bismuth oxide were generated, and the XRD pattern also shifted. Therefore, it can be concluded that chromium and bismuth have been incorporated into copper cobalt oxide.

[0068] Example 8

[0069] SEM test

[0070] From the literature reviewed, the effects of bismuth doping on morphology and other aspects of material modification were discussed. Figure 8 The same applies to bismuth doping and the effect of chromium doping on morphology. Figure 9 The same applies to chromium doping, which leads us to conclude that both bismuth and chromium are doped in.

[0071] Example 9

[0072] Performance testing

[0073] The Cu obtained in Example 1 0.95Bi 0.05 The application of Co2O4 doped materials as electrode materials in lithium-ion batteries includes the following steps:

[0074] (1) Preparation of negative electrode: The Cu obtained in Example 1 was used to prepare the negative electrode. 0.95 Bi 0.05 Weigh 70 mg of Co2O4 doped material, mix it with 20 mg of conductive agent superP and 10 mg of binder polyvinylidene fluoride (PVDF) and grind it for 20 min to obtain a uniformly mixed negative electrode material. Add 0.5 mL of N-methylpyrrolidone and continue grinding to obtain a uniformly dispersed negative electrode material. Coat the negative electrode material evenly on copper foil with a scraper and dry it under vacuum at 80 °C for 12 h to obtain a negative electrode sheet.

[0075] (2) Assembly of button batteries: Using lithium metal sheets as the counter electrode, 2016 type button batteries were made in a glove box filled with argon gas. Celgard 2400 separator was used as the separator, and LiPF6 / EC:DEC with a concentration of 1M (volume ratio 1:1) was used as the electrolyte.

[0076] The fabricated 2016-type button cell battery was tested for performance using a Blue Electric testing system. The electrochemical energy storage performance of the fabricated lithium-ion battery was also tested. Figure 1 It is Cu 0.95 Bi 0.05 Cyclic performance of Co2O4 doped material at different charge-discharge current densities of 0.1C, 0.2C, 0.5C, 1C, and 2C.

[0077] Depend on Figure 1 It can be seen that the Cu obtained using Example 1 0.95 Bi 0.05 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 1035 mAh / g at 0.1C; it demonstrates good charge-discharge stability and is also very stable with lithium-ion batteries; Cu 0.95 Bi 0.05 The battery capacity of Co2O4 doped materials is significantly improved.

[0078] Depend on Figure 1 It can be seen that using the Cu obtained in Example 1 0.95 Bi 0.05 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 1000 mAh / g at 0.2C; it demonstrates good charge-discharge stability and is also very stable with lithium-ion batteries. 0.95 Bi 0.05 The battery capacity of Co2O4 doped materials is significantly improved.

[0079] Depend on Figure 1It can be seen that the Cu obtained using Example 1 0.95 Bi 0.05 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 976 mAh / g at 0.5C; it demonstrates good charge-discharge stability and is also very stable with lithium-ion batteries; Cu 0.95 Bi 0.05 The battery capacity of Co2O4 doped materials is significantly improved.

[0080] Depend on Figure 1 It can be seen that the Cu obtained using Example 1 0.95 Bi 0.05 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 790 mAh / g at 1C current, demonstrating good charge-discharge stability and excellent stability, similar to lithium-ion batteries. Among these, Cu... 0.95 Bi 0.05 The battery capacity of Co2O4 doped materials is significantly improved.

[0081] Figure 2 The performance graph is based on 65 cycles at a current density of 0.1C. Figure 2 It can be seen that the Cu obtained using Example 1 0.95 Bi 0.05 When Co2O4 doped materials are assembled into a half-cell (with lithium foil as the counter electrode), its specific capacity is about 400 mAh / g; it has good charge and discharge stability and is a very stable lithium-ion battery.

[0082] The above performance figures show that the CR2016 coin cell of Example 1 of this application, which uses bismuth-doped copper cobalt oxide as the negative electrode active material, lithium sheet as the counter electrode, 1M LiF6 as the solute, and EC and DEC as organic solvents (volume ratio 1:1) as the electrolyte, has good electrochemical performance, good rate performance, high coulombic efficiency and long cycle life.

[0083] This application obtains Cu by in-situ doping of bismuth through a combination of solvothermal and calcination. 0.95 Bi 0.05 Co2O4 materials. Due to bismuth doping, copper cobalt oxide exhibits excellent electrochemical properties and significant morphological changes.

[0084] The negative electrode material containing the above-mentioned bismuth-doped copper cobalt oxide material can enhance the conductive connection between electrode particles, significantly improve the specific capacity of lithium-ion batteries, and exhibit excellent rate performance and better cycle stability as an electrode material.

[0085] Example 10

[0086] Performance testing

[0087] The Cu obtained in Example 2 0.9 Cr 0.1 The application of Co2O4 doped materials as electrode materials in lithium-ion batteries includes the following steps:

[0088] (1) Preparation of negative electrode: The Cu obtained in Example 2 was used to prepare the negative electrode. 0.9 Cr 0.1 Weigh 70 mg of Co2O4 doped material, mix it with 20 mg of conductive agent superP and 10 mg of binder polyvinylidene fluoride (PVDF) and grind it for 20 min to obtain a uniformly mixed negative electrode material. Add 0.5 mL of N-methylpyrrolidone and continue grinding to obtain a uniformly dispersed negative electrode material. Coat the negative electrode material evenly on copper foil with a scraper and dry it under vacuum at 80 °C for 12 h to obtain a negative electrode sheet.

[0089] (2) Assembly of button batteries: Using lithium metal sheets as the counter electrode, 2016 type button batteries were made in a glove box filled with argon gas. Celgard 2400 separator was used as the separator, and LiPF6 / EC:DEC with a concentration of 1M (volume ratio 1:1) was used as the electrolyte.

[0090] The fabricated 2016-type button cell battery was tested for performance using a Blue Electric testing system. The electrochemical energy storage performance of the fabricated lithium-ion battery was also tested. Figure 3 It is Cu 0.9 Cr 0.1 Cyclic performance of Co2O4 doped material at different charge-discharge current densities of 0.1C, 0.2C, 0.5C, 1C, and 2C.

[0091] Depend on Figure 3 It can be seen that the Cu obtained using Example 2 0.9 Cr 0.1 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 1190 mAh / g at 0.1C; it demonstrates good charge-discharge stability and is also very stable with lithium-ion batteries; Cu 0.9 Cr 0.1 The battery capacity of Co2O4 doped materials is significantly improved.

[0092] Depend on Figure 3 It can be seen that using the Cu obtained in Example 2 0.9 Cr 0.1 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 1100 mAh / g at 0.2C; it demonstrates good charge-discharge stability and is also very stable with lithium-ion batteries. 0.9 Cr 0.1 The battery capacity of Co2O4 doped materials is significantly improved.

[0093] Depend on Figure 3 It can be seen that the Cu obtained using Example 2 0.9 Cr 0.1 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 970 mAh / g at 0.5C; it demonstrates good charge-discharge stability and is also very stable with lithium-ion batteries; Cu 0.9 Cr 0.1 The battery capacity of Co2O4 doped materials is significantly improved.

[0094] Depend on Figure 3 It can be seen that the Cu obtained using Example 2 0.9 Cr 0.1 A half-cell assembled with Co2O4 doped material (using a lithium sheet as the counter electrode) exhibits a specific capacity of approximately 790 mAh / g at 1C current, demonstrating good charge-discharge stability and excellent stability, similar to lithium-ion batteries. Among these, Cu... 0.9 Cr 0.1 The battery capacity of Co2O4 doped materials is significantly improved.

[0095] Figure 4 The performance graph is based on 60 cycles at a current density of 0.1C. Figure 4 It can be seen that the Cu obtained using Example 2 0.9 Cr 0.1 When Co2O4 doped materials are assembled into a half-cell (with lithium foil as the counter electrode), the specific capacity is about 580 mAh / g; the charge and discharge stability is good, and the lithium-ion battery is very stable.

[0096] The above performance figures show that the CR2016 coin cell, which uses chromium-doped copper cobalt oxide as the negative electrode active material, lithium sheet as the counter electrode, 1M LiF6 as the solute, and EC and DEC as organic solvents (volume ratio 1:1) as the electrolyte, has good electrochemical performance, good rate performance, high coulombic efficiency and long cycle life.

[0097] This application obtains Cu by in-situ doping with chromium through a combination of hydrothermal method and calcination. 0.9 Cr 0.1 Co2O4. Due to chromium doping, copper cobalt oxide exhibits excellent electrochemical properties and significant morphological changes.

[0098] The negative electrode material containing the above-mentioned chromium-doped copper cobalt oxide material can enhance the conductive connection between electrode particles, significantly improve the specific capacity of lithium-ion batteries, and exhibit excellent rate performance and excellent cycle stability as an electrode material.

[0099] Example 11

[0100] Performance testing

[0101] The pure CuCo2O4 material prepared in Comparative Example 1 was used as an electrode material in a lithium-ion battery. The specific steps included:

[0102] (1) Preparation of negative electrode: Weigh 70 mg of CuCo2O4 material obtained in Comparative Example 1, mix and grind with 20 mg of conductive agent superP and 10 mg of binder polyvinylidene fluoride (PVDF) for 20 min to obtain a uniformly mixed negative electrode material, add 0.5 mL of N-methylpyrrolidone, continue grinding to obtain a uniformly dispersed negative electrode material, coat the negative electrode material evenly on copper foil with a scraper, and vacuum dry at 80 °C for 12 h to obtain a negative electrode sheet;

[0103] (2) Assembly of button batteries: Using lithium metal sheets as the counter electrode, 2016 type button batteries were made in a glove box filled with argon gas. Celgard 2400 separator was used as the separator, and LiPF6 / EC:DEC with a concentration of 1M (volume ratio 1:1) was used as the electrolyte.

[0104] The fabricated 2016-type button cell battery was tested for performance using a Blue Electric testing system. The electrochemical energy storage performance of the fabricated lithium-ion battery was also tested. Figure 5 The graph shows the cycling performance of CuCo2O4 material at different charge / discharge current densities of 0.1C, 0.2C, 0.5C, 1C, and 2C.

[0105] Depend on Figure 5 It can be seen that the CuCo2O4 material prepared in Comparative Example 1, when assembled into a half-cell (with lithium sheet as counter electrode), has a specific capacity of approximately 1025 mAh / g at a current of 0.1C.

[0106] Depend on Figure 5 It can be seen that when the CuCo2O4 material prepared in Comparative Example 1 is assembled into a half cell (with lithium sheet as counter electrode), the specific capacity is about 995 mAh / g at a current of 0.2C.

[0107] Depend on Figure 5 It can be seen that the CuCo2O4 material prepared in Comparative Example 1, when assembled into a half-cell (with a lithium sheet as the counter electrode), has a specific capacity of approximately 936 mAh / g at a current of 0.5C.

[0108] Depend on Figure 5 It can be seen that the CuCo2O4 material prepared in Comparative Example 1, when assembled into a half-cell (with lithium sheet as counter electrode), has a specific capacity of approximately 766 mAh / g at a current of 1C.

[0109] Figure 6 The performance graph is based on 60 cycles at a current density of 0.1C. Figure 6It can be seen that the specific capacity of a half-cell assembled with CuCo2O4 material prepared in Comparative Example 1 (with lithium sheet as counter electrode) is about 390 mAh / g.

[0110] The above performance figures show the CR2016 coin cell composed of pure copper cobalt oxide material as the negative electrode active material, lithium sheet as the counter electrode, 1M LiF6 as the solute, and EC and DEC as organic solvents (volume ratio 1:1).

[0111] This application obtained a pure CuCo2O4 sample through a combination of hydrothermal method and calcination.

[0112] Example 12

[0113] Cyclic Voltmeter Curve Test

[0114] Cyclic voltammetry curves can reveal the internal reaction processes of negative electrode materials, such as... Figure 12 The first two cycles of cyclic voltammetry for the pure copper cobalt oxide electrode were obtained, with a scan voltage range of 0-3 V and a scan rate of 0.1 mV / s. During the first scan, a reduction peak was observed at 2.12 V, which is attributed to the decomposition of the electrolyte and the formation of the SEI on the surface of the negative electrode material during the initial discharge process. As the reaction progressed, a stronger reduction peak appeared near 2.2 V, corresponding to the process of lithium ion intercalation into the copper cobalt oxide to form an alloy. In subsequent scans, strong oxidation peaks appeared near 0.75 V, corresponding to the process of lithium ion extraction from the copper cobalt oxide lithium alloy. The entire process of lithium ion intercalation and extraction in the copper cobalt oxide electrode was detected from the first cycle of cyclic voltammetry.

[0115] Cyclic voltammetry curves can reveal the internal reaction processes of negative electrode materials, such as... Figure 10 The first two cycles of cyclic voltammetry for the bismuth-doped electrode were performed with a scan voltage range of 0-3 V and a scan rate of 0.1 mV / s. During the first scan, a reduction peak was observed at 2.2 V, which is attributed to the decomposition of the electrolyte and the formation of the SEI on the surface of the negative electrode material during the initial discharge. As the reaction progressed, a stronger reduction peak appeared near 2.25 V, corresponding to the process of lithium ions intercalating into the bismuth-doped copper cobalt oxide to form an alloy. In subsequent scans, strong oxidation peaks appeared near 0.8 V, corresponding to the process of lithium ions being extracted from the bismuth-doped copper cobalt oxide lithium alloy. The entire process of lithium ion intercalation and extraction in the bismuth-doped copper cobalt oxide electrode was detected from the first cycle of cyclic voltammetry. In subsequent cycles, the intensity of the reduction peak near 2.25 V and the oxidation peak near 1.25 V gradually increased, indicating that the bismuth-doped copper cobalt oxide electrode was gradually activated, and the material contained more active sites.

[0116] Cyclic voltammetry curves can reveal the internal reaction processes of negative electrode materials, such as... Figure 11 The first two cycles of cyclic voltammetry for the chromium-doped electrode were performed with a scan voltage range of 0-3V and a scan rate of 0.1mV / s. During the first scan, a reduction peak was observed at 2.1V, which is attributed to the decomposition of the electrolyte and the formation of the SEI on the surface of the negative electrode material during the initial discharge process. As the reaction progressed, a stronger reduction peak appeared near 2.15V, corresponding to the process of lithium ions intercalating into the chromium-doped copper cobalt oxide to form an alloy. In subsequent scans, strong oxidation peaks appeared near 0.78V, corresponding to the process of lithium ions being extracted from the chromium-doped copper cobalt oxide lithium alloy. The entire process of lithium ion intercalation and extraction in the chromium-doped copper cobalt oxide electrode was detected from the first cycle of cyclic voltammetry. In subsequent cycles, the intensity of the reduction peak near 2.15V and the oxidation peak near 1.25V gradually increased, indicating that the chromium-doped copper cobalt oxide electrode was gradually activated, and the material contained more active sites.

[0117] Example 13

[0118] Electrochemical impedance spectroscopy

[0119] Electrochemical impedance spectroscopy (EIS) can be divided into two regions. The low-frequency region of the EIS is represented by a diagonal line corresponding to the lithium-ion diffusion process, while the high-frequency region is represented by a semicircle corresponding to the charge transfer resistance of the electrode. The charge transfer resistance is determined by the diameter of this semicircle. Figure 13 The charge transfer resistance of bismuth-doped copper cobalt oxide was 280Ω. Figure 13 The charge transfer resistance of chromium-doped copper cobalt oxide was 250Ω. These results indicate that as the lithium insertion / de-lithiation reaction continues, the lithium insertion depth of the bismuth-doped and chromium-doped electrodes gradually increases and the structure remains stable, thus maintaining efficient lithium-ion transport.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A transition metal-doped copper cobalt oxide nanomaterial, characterized in that, The chemical formula of the transition metal-doped copper cobalt oxide nanomaterial is: Cu 1-x M x Co2O4, where M represents a transition metal and x takes values ​​in the range of 0.05 ≤ x ≤ 0.1; The transition metal is Bi or Cr; The transition metal is Bi, and x takes a value of 0.05; The transition metal is Cr, and x takes the value 0.

1.

2. A method for preparing the transition metal-doped copper cobalt oxide nanomaterial of claim 1, characterized in that, Includes the following steps: Step 1: Weigh out the copper source, cobalt source, transition metal source and precipitant according to the stoichiometric ratio of the chemical formula of the transition metal-doped copper cobalt oxide nanomaterial, dissolve them in an appropriate amount of organic solvent, stir evenly to obtain a mixed solution; Step 2: Perform hydrothermal treatment on the mixed solution to obtain an intermediate substance; Step 3: Calcine the intermediate material to obtain transition metal-doped copper cobalt oxide nanomaterials.

3. The method according to claim 2, characterized in that, Specifically, the steps include the following: Step 1: Weigh (1-x) mmol of copper source, 2 mmol of cobalt source and x mmol of transition metal source according to the stoichiometric ratio of the chemical formula of the transition metal-doped copper cobalt oxide nanomaterial, dissolve them in 60-x mL of organic solvent, then add 6.67 mmol of precipitant, stir and mix evenly under a magnetic stirrer at 200 rpm, and sonicate to obtain a mixed solution. Step 2: Place the mixed solution into a reaction vessel for hydrothermal reaction at a temperature of 140°C for 10 hours to obtain a precipitate, which is then washed and dried to obtain an intermediate substance. Step 3: Calcine the intermediate material in air at a temperature of 450-650℃ for 2 hours to obtain transition metal-doped copper cobalt oxide nanomaterials.

4. The method according to claim 2 or 3, characterized in that, The copper source is one or more of copper nitrate trihydrate, copper nitrate hexahydrate, copper sulfate, and copper chloride.

5. The method according to claim 2 or 3, characterized in that, The cobalt source is one or more of cobalt nitrate hexahydrate, cobalt sulfate heptahydrate, cobalt chloride, and cobalt tetroxide.

6. The method according to claim 2 or 3, characterized in that, The transition metal source is a bismuth source and / or a chromium source; The bismuth source is one or more of bismuth nitrate, bismuth trichloride, and bismuth citrate. The chromium source is one or more of chromium nitrate, chromium trioxide, and basic chromium sulfate.

7. The method according to claim 2 or 3, characterized in that, The organic solvent is one or more of N,N-dimethylformamide, ethanol, and acetone; the precipitant is urea and / or polyacrylamide.

8. A negative electrode sheet, characterized in that, The negative electrode contains the nanomaterial as described in claim 1 or the nanomaterial prepared by any one of claims 2-7.

9. A battery, characterized in that, The battery includes the negative electrode sheet as described in claim 8, and further includes a battery casing, a positive electrode sheet, a separator, and an electrolyte.

Images