Single-oriented copper metal negative electrode and preparation method and application thereof

Abstract

The application belongs to the technical field of lithium ion batteries, and specifically discloses a single-orientation copper metal negative electrode and a preparation method and application thereof. The application also includes application of the single-orientation electrolytic copper foil negative electrode material to preparation of a lithium ion battery. The single-orientation copper foil can be obtained by screening (200) crystal faces, and the (200) crystal face single-orientation copper has a lower atomic density and weaker interatomic interaction force, so that the (200) crystal face orientation of the copper can effectively improve the reaction activity of the copper negative electrode. After 100 cycles at a high temperature 1.0 C rate, the specific capacity of the prepared (200) crystal face single-orientation copper is as high as 183.5 mAhg ‑1 , and the capacity retention rate is 88.1%, which is much higher than 55.1% of the untreated one. Meanwhile, the (200) crystal face single-orientation copper also has excellent high-voltage performance.

Description

Technical Field

[0001] This invention relates to a single-oriented copper metal anode, its preparation method, and its application, belonging to the field of lithium-ion battery technology. Background Technology

[0002] Energy crisis and environmental pollution are common challenges facing countries worldwide. my country's current energy structure remains dominated by fossil fuels, resulting in an irrational energy structure, low energy utilization, and severe environmental impact. Therefore, accelerating the upgrading of the energy structure and vigorously developing sustainable and environmentally friendly renewable energy sources is urgently needed. However, renewable energy power generation is unstable and discontinuous, requiring the development of efficient energy storage systems to coordinate renewable energy grid connection and improve the grid's tolerance to renewable energy generation. Electrochemical energy storage technology, as an emerging energy storage technology, has attracted widespread attention from researchers. Currently, the most widely used chemical energy storage device is the lithium-ion battery. With the continuous development of high-energy-density lithium-ion battery technology, the operating range of electric vehicles powered by lithium-ion batteries is gradually increasing, and their market share is also rising. However, as high-energy-density lithium-ion batteries are continuously introduced to the market, their inherent problems are also being exposed, such as rapid battery degradation and poor rate performance. In particular, incidents of electric vehicle fires and injuries caused by battery fires and explosions are occurring frequently, greatly raising public concern and anxieties about electric vehicle safety. In the first half of 2020 alone, more than 20 electric vehicle fires occurred in my country, involving 28 electric vehicles. Most of these vehicles were powered by high-energy-density lithium-ion batteries assembled with nickel-rich cathode materials. In terms of timing, electric vehicle fires were less frequent from January to March, gradually increasing from April to June, with July to September being the peak period. This is mainly because July to September is the high-temperature season, and the internal temperature of electric vehicles rises sharply under the summer sun.

[0003] In recent years, only a few studies have been reported on copper metal anodes. Some studies have shown that subgrain and refined grain structures effectively improve the overall uniformity of the metal and suppress pitting and intergranular corrosion. On the other hand, constructing crystal defects and refining grain size increases the number of grain boundaries. This invention shows that the (200) crystal plane of copper has a lower atomic density and weaker interatomic interaction forces, and constructing the (200) crystal plane orientation of copper can effectively improve the electrochemical performance of copper metal anodes. Although materials science issues such as grain size and crystal plane orientation have been studied extensively in traditional copper alloys, their influence on the interfacial electrochemical behavior of copper anodes is usually ignored, and the reaction mechanism of these material structural characteristics when copper is used as an electrode material is still unclear.

[0004] Therefore, designing, preparing, and investigating the influence of different crystal plane exposure characteristics of copper metal materials on the interface state of copper anodes, thereby obtaining unique guiding ideas for the design of copper anode materials, has very important practical and academic value and is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a single-oriented copper metal anode, its preparation method, and its application. The aim is to construct a single-oriented crystal plane for the copper metal anode (single orientation refers to the (200) crystal plane of copper having a crystal plane preference of 80%) through preferential crystal plane selection, thereby suppressing pitting and intergranular corrosion and increasing the number of grain boundaries. On the one hand, copper anodes with different crystal planes produce different polarizations, suppressing anode corrosion. On the other hand, different crystal planes have different atomic densities, resulting in weaker interatomic interactions, reducing anode heating, and thus improving the electrochemical performance of lithium-ion batteries.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a single-oriented copper metal anode includes the following steps: cleaning the copper foil and directly heat-treating it under an inert atmosphere to obtain the anode.

[0008] Furthermore, the cleaned copper foil is heat-treated in an inert atmosphere (in a tube furnace) at a temperature of 100–500°C, a heating rate of 3–10°C / min, and a heat treatment time of 0.5–3 h.

[0009] Furthermore, the heat treatment temperature is 200–500°C, preferably 300–450°C.

[0010] A further preferred embodiment involves heat-treating the pre-oxidized copper foil in a tube furnace under an inert atmosphere. The heat treatment temperature is 450°C, the heating rate is 10°C / min, and the heat treatment time is 2 hours.

[0011] When the heat treatment temperature is between 100-500℃, the orientation preference of the (200) crystal plane is higher than 80%. Temperatures below 450℃ will allow the orientation preference of the (200) crystal plane to reach a maximum of 100%, while temperatures above 450℃ will cause the crystal phase structure of copper to become disordered.

[0012] The preparation method described herein uses copper foil comprising at least one of commercial electrolytic copper foil, porous copper foil, and Cu-Zn alloy copper foil, preferably commercial electrolytic copper foil; more preferably commercial pure ultrathin electrolytic copper foil with a purity of 99.99%.

[0013] Commercial pure ultrathin electrolytic copper foil has a highly ordered crystal phase structure, which is beneficial for subsequent heat treatment. Other copper foils have other elemental impurities or uneven mechanical structures, which also have a certain impact on the crystal phase structure.

[0014] Furthermore, the copper foil is cleaned using at least one of deionized water, ethanol, and acetone; preferably, ethanol and deionized water are used alternately to clean the copper foil. It is preferable to use deionized ethanol and deionized water alternately to repeatedly clean the copper foil three times, each time for 10 minutes.

[0015] Cleaning copper foil can remove inorganic impurities, grease, and dust from its surface.

[0016] The preparation method described herein uses an inert atmosphere comprising at least one of N2, Ar, He, and H2; preferably an Ar atmosphere.

[0017] The present invention also provides a single-oriented copper metal anode prepared by the aforementioned preparation method, wherein the copper in the copper metal anode has a single orientation of the (200) crystal plane, the heat treatment temperature is between 100-500℃, and the crystal plane selectivity of the (200) crystal plane is higher than 80%. At a heat treatment temperature of 450℃, the crystal plane selectivity of the (200) crystal plane reaches 100%.

[0018] Another object of the present invention is to provide a lithium-ion battery in which the single-oriented copper metal prepared by the above-described preparation method is used as the negative electrode.

[0019] Taking lithium-ion batteries as an example, the traditional alloying mechanism is to reduce the heat generation of copper anode materials and improve their electrochemical performance by adding magnesium, zinc, indium, gallium, and aluminum to copper. However, the long-term heat generation effect of copper alloy anodes in electrolytes is still not ideal. The single-oriented copper metal anode of this invention obtains single (200) oriented copper through simple heat treatment, which can achieve an action mechanism different from conventional alloying, specifically as follows:

[0020] (1) Unidirectional copper metal with a (200) crystal plane has a lower atomic density and weaker interatomic interaction forces, reducing heat generation at the negative electrode. The surface density of the (200) crystal plane is calculated to be 6.4 nm. -2 13.1 nm lower than the (111) plane -2 and 10.9nm of (220) plane -2 .

[0021] (2)(200) Unidirectional copper metal with crystal plane can adjust the electrochemical behavior of the copper anode surface, making the copper anode interface reaction uniform, improving the utilization rate, and effectively maintaining the capacity.

[0022] (3)(200) Single-oriented copper metal with crystal plane can effectively suppress side reactions and reduce the corrosion of negative electrode metal, improve the utilization rate of prototype, and at the same time exhibit excellent high voltage performance.

[0023] Compared with the prior art, the technical solution of the present invention brings the following beneficial effects:

[0024] (1) The single-oriented copper metal anode of the present invention has a simple preparation method, low cost, safety and environmental protection requirements. It can not only significantly reduce the corrosion rate of copper anode, but also effectively maintain the capacity of copper anode and exhibit excellent high voltage performance. The utilization rate of anode is increased, and copper anode has good corrosion resistance and high electrochemical activity to meet the high capacity requirements of lithium-ion batteries.

[0025] (2) The single-oriented copper metal anode of the lithium-ion battery of the present invention can not only control the utilization rate of the lithium-ion battery anode, but also ensure that the copper anode alloy and the ternary cathode have high electrochemical activity, which is of great significance for improving battery performance and extending discharge life, and is conducive to large-scale promotion and application.

[0026] (3) The method for preparing the single-oriented copper metal anode of lithium-ion battery of the present invention is simple, easy to implement, low in cost, and has good application prospects.

[0027] (4) The (200) single-oriented copper metal anode prepared by the present invention is used in lithium-ion batteries. After 100 cycles at room temperature and 1.0C rate, the capacity retention rate of the lithium-ion battery is 89.9%. Attached Figure Description

[0028] Figure 1 The images show the XRD patterns of copper metal anodes prepared by treating copper foil at three different temperatures in Examples 1-6.

[0029] Figure 2 Capacity curves from charge-discharge tests performed in Examples 1-3;

[0030] Figure 3 The capacity curves for charge-discharge tests performed in Examples 4 to 6 are shown. Detailed Implementation

[0031] Example 1

[0032] In this embodiment, the copper metal negative electrode is a commercially pure copper foil after heat treatment.

[0033] The copper metal negative electrode obtained in this embodiment was assembled into a 2016 type button battery and charged and discharged within a voltage range of 3.0-4.3V.

[0034] The method for preparing the copper metal anode of a lithium-ion battery in this embodiment includes the following steps:

[0035] Commercial pure copper foil was repeatedly washed three times with alternating ethanol and deionized water, each time for 10 minutes.

[0036] The cleaned commercial pure copper foil was heat-treated in an Ar atmosphere at a temperature of 150°C, a rate of 10°C / min, for 2 hours, and then cooled to room temperature in an Ar atmosphere.

[0037] The test conditions were as follows: at 25°C, the device was first activated once at 0.2°C and 0.5°C, and then circulated 100 times at 1.0°C.

[0038] The lithium-ion battery in this embodiment uses the aforementioned copper metal negative electrode.

[0039] Example 2

[0040] In this embodiment, the copper metal negative electrode is a commercially pure copper foil after heat treatment.

[0041] The copper metal negative electrode obtained in this embodiment was assembled into a 2016 type button battery and charged and discharged within a voltage range of 3.0-4.3V.

[0042] The method for preparing the copper metal anode of a lithium-ion battery in this embodiment includes the following steps:

[0043] Commercial pure copper foil was repeatedly washed three times with alternating ethanol and deionized water, each time for 10 minutes.

[0044] The cleaned commercial pure copper foil was heat-treated in an Ar atmosphere at a temperature of 300℃, a rate of 10℃ / min, and a time of 2 hours, and then cooled to room temperature in an Ar atmosphere.

[0045] The test conditions were as follows: at 25°C, the device was first activated once at 0.2°C and 0.5°C, and then circulated 100 times at 1.0°C.

[0046] The lithium-ion battery in this embodiment uses the aforementioned copper metal negative electrode.

[0047] Example 3

[0048] In this embodiment, the copper metal negative electrode is a commercially pure copper foil after heat treatment.

[0049] The copper metal negative electrode obtained in this embodiment was assembled into a 2016 type button battery and charged and discharged within a voltage range of 3.0-4.3V.

[0050] The method for preparing the copper metal anode of a lithium-ion battery in this embodiment includes the following steps:

[0051] Commercial pure copper foil was repeatedly washed three times with alternating ethanol and deionized water, each time for 10 minutes.

[0052] The cleaned commercial pure copper foil was heat-treated in an Ar atmosphere at a temperature of 450°C, a rate of 10°C / min, for 2 hours, and then cooled to room temperature in an Ar atmosphere.

[0053] The test conditions were as follows: at 25°C, the device was first activated once at 0.2°C and 0.5°C, and then circulated 100 times at 1.0°C.

[0054] The lithium-ion battery in this embodiment uses the aforementioned copper metal negative electrode.

[0055] Example 4

[0056] In this embodiment, the copper metal negative electrode is a commercially pure copper foil after heat treatment.

[0057] The copper metal negative electrode obtained in this embodiment was assembled into a 2016 type button battery and charged and discharged within a voltage range of 3.0-4.3V.

[0058] The method for preparing the copper metal anode of a lithium-ion battery in this embodiment includes the following steps:

[0059] Commercial pure copper foil was repeatedly washed three times with alternating ethanol and deionized water, each time for 10 minutes.

[0060] The cleaned commercial pure copper foil was heat-treated in an Ar atmosphere at a temperature of 150°C, a rate of 10°C / min, for 2 hours, and then cooled to room temperature in an Ar atmosphere.

[0061] The test conditions were: activation at 0.2C and 0.5C for one cycle at 50℃, followed by 100 cycles at 1.0C.

[0062] The lithium-ion battery in this embodiment uses the aforementioned copper metal negative electrode.

[0063] Example 5

[0064] In this embodiment, the copper metal negative electrode is a commercially pure copper foil after heat treatment.

[0065] The copper metal negative electrode obtained in this embodiment was assembled into a 2016 type button battery and charged and discharged within a voltage range of 3.0-4.3V.

[0066] The method for preparing the copper metal anode of a lithium-ion battery in this embodiment includes the following steps:

[0067] Commercial pure copper foil was repeatedly washed three times with alternating ethanol and deionized water, each time for 10 minutes.

[0068] The cleaned commercial pure copper foil was heat-treated in an Ar atmosphere at a temperature of 300℃, a rate of 10℃ / min, and a time of 2 hours, and then cooled to room temperature in an Ar atmosphere.

[0069] The test conditions were: activation at 0.2C and 0.5C for one cycle at 50℃, followed by 100 cycles at 1.0C.

[0070] The lithium-ion battery in this embodiment uses the aforementioned copper metal negative electrode.

[0071] Example 6

[0072] In this embodiment, the copper metal negative electrode is a commercially pure copper foil after heat treatment.

[0073] The copper metal negative electrode obtained in this embodiment was assembled into a 2016 type button battery and charged and discharged within a voltage range of 3.0-4.3V.

[0074] The method for preparing the copper metal anode of a lithium-ion battery in this embodiment includes the following steps:

[0075] Commercial pure copper foil was repeatedly washed three times with alternating ethanol and deionized water, each time for 10 minutes.

[0076] The cleaned commercial pure copper foil was heat-treated in an Ar atmosphere at a temperature of 450°C, a rate of 10°C / min, for 2 hours, and then cooled to room temperature in an Ar atmosphere.

[0077] The test conditions were: activation at 0.2C and 0.5C for one cycle at 50℃, followed by 100 cycles at 1.0C.

[0078] The lithium-ion battery in this embodiment uses the aforementioned copper metal negative electrode.

[0079] Figure 1 The images show the XRD patterns of copper metal anodes prepared by treating copper foil at three different temperatures in Examples 1-6. Figure 1 As can be seen, at a heat treatment temperature of 150℃, the (111) and (220) crystal plane orientations of copper are significantly weakened. In the untreated copper foil, the (220) crystal plane orientation is the most prominent, and with heat treatment, the (220) crystal plane orientation of copper has been significantly weakened. Furthermore, as the heat treatment temperature gradually increases, the (111) and (220) crystal plane orientations of copper also gradually weaken. When the heat treatment temperature is 450℃, the (111) and (220) crystal plane orientations of copper have been completely removed, and the copper negative electrode obtained at this time has a single (200) crystal plane orientation. And from... Figure 1 As can be seen from this, when the heat treatment temperature is 450℃, the crystal plane preference of copper (200) reaches 100%.

[0080] Figure 2Capacity curves from charge-discharge tests of Examples 1-3 are shown. The copper foils obtained in Examples 1-3 were assembled into 2016-type button batteries and subjected to charge-discharge tests within a voltage range of 3.0-4.3V. The test conditions were: activation at 0.2C and 0.5C for one cycle at 25°C, followed by 100 cycles at 1.0C. As the (111) and (220) crystal plane orientations of the copper decreased, the capacity decay after cycling gradually decreased. When the copper negative electrode had a single (200) crystal plane orientation, after 100 cycles at 25°C and a 1.0C rate, its capacity retention rate was 89.9%, while the capacity retention rate of the untreated original copper foil was only 76.1%.

[0081] Figure 3 Capacity curves for charge-discharge tests in Examples 4-6 are shown. The copper foils obtained in Examples 1-3 were assembled into 2016-type button batteries and subjected to charge-discharge tests within a voltage range of 3.0-4.3V. The test conditions were: activation at 0.2C and 0.5C for one cycle at a high temperature of 50°C, followed by 100 cycles at 1.0C. As the (111) and (220) crystal plane orientations of copper decreased, the capacity decay after cycling gradually decreased. When the copper negative electrode had a single (200) crystal plane orientation, the specific capacity remained as high as 183.1 mAh g⁻¹ after 100 cycles at a high temperature of 50°C and a 1.0C rate, with a capacity retention rate of 88.1%, while the capacity retention rate of the untreated original copper foil was only 55.1%.

[0082] Comparative Example 1

[0083] The other steps are the same as in Example 1, except that no subsequent heat treatment is performed.

[0084] Comparative Example 2

[0085] The other steps are the same as in Example 4, except that no subsequent heat treatment is performed.

[0086] Performance testing

[0087] The charge-discharge performance of the copper negative electrodes prepared in Examples 1-6 and Comparative Examples 1-2 was tested using charge-discharge tests. The copper foils obtained in Examples 1-3 were assembled into 2016-type button batteries and subjected to charge-discharge tests within a voltage range of 3.0-4.3V. The test conditions were 25℃ and 50℃, with initial activation at 0.2C and 0.5C for one cycle, followed by 100 cycles at 1.0C. The data are shown in Tables 1 and 2.

[0088] Table 1. Comparison of electrical properties of the materials in the examples and comparative examples (tested at 25°C)

[0089]

[0090] Table 2. Comparison of electrical properties of the materials in the examples and comparative examples (tested at 50°C)

[0091]

[0092] As can be seen from Tables 1 and 2, with increasing temperature, the (111) and (220) crystal plane orientations of copper decrease, the capacity decay after cycling gradually decreases, and the utilization rate of the copper anode increases. When the heat treatment temperature is 450℃, the copper anode has a 100% single (200) crystal plane orientation. After 100 cycles at 25℃ and a 1.0C rate, its capacity retention rate is 89.9%, while the capacity retention rate of untreated pure copper foil is only 76.1%. In addition, after 100 cycles at 50℃ and a 1.0C rate, the specific capacity is still as high as 183.1 mAh g⁻¹, with a capacity retention rate of 88.1%, which is much higher than the 55.1% of the untreated pure copper foil.

[0093] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a unidirectional copper metal anode, characterized in that the steps include... include: The copper foil is cleaned and then heat-treated in an inert atmosphere to obtain the product. Clean the copper foil using at least one of deionized water, ethanol, or acetone; or clean the copper foil repeatedly with alternating ethanol and deionized water three times, each time for 10 minutes. The copper in the copper metal anode has a single orientation of (200) crystal plane, and the crystal plane preference of (200) crystal plane is higher than 80%. The cleaned copper foil is heat-treated in an inert atmosphere at a temperature of 100–450°C, a heating rate of 3–10°C / min, and a heat treatment time of 0.5–3 h.

2. The preparation method according to claim 1, characterized in that, The heat treatment temperature is 200–450°C.

3. The preparation method according to claim 1, characterized in that, Inert atmospheres include at least one of N2, Ar, He, and H2.

4. The preparation method according to claim 1, characterized in that, Copper foil includes at least one of commercial electrolytic copper foil, porous copper foil, and Cu-Zn alloy copper foil.

5. A lithium-ion battery, characterized in that: The unidirectional copper metal prepared by the preparation method described in claim 1 is used as the negative electrode.

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