A sodium-ion battery positive electrode and a sodium-ion battery

Abstract

This application provides a sodium-ion battery positive electrode sheet and a sodium-ion battery. The sodium-ion battery positive electrode sheet includes: a positive electrode current collector and a positive electrode active material disposed on the surface of the positive electrode current collector; the positive electrode active material includes an intercalation-deintercalation type positive electrode material and an adsorption type positive electrode material; the amount of positive electrode active material on the surface of the positive electrode current collector is 0.2 to 0.8 g per square decimeter. Using the above-mentioned sodium-ion battery positive electrode sheet, the sodium-ion battery maintains a power density of 2 kW / kg to 3.5 kW / kg and a battery energy density of 40 Wh / kg to 80 Wh / kg, meeting the requirements for HEV battery packs.

Description

Technical Field

[0001] This article relates to, but is not limited to, the field of energy storage, and particularly to, but is not limited to, a sodium-ion battery cathode and a sodium-ion battery. Background Technology

[0002] With increasing public concern about fuel efficiency and environmental protection, the electrification trend of passenger vehicles is becoming more and more apparent, giving rise to hybrid electric vehicles (HEVs). For HEVs, their small-capacity batteries can meet all functions except for long-term pure electric performance, such as low-speed pure electric operation, regenerative braking, and improved acceleration. Compared to plug-in hybrids and pure electric vehicles, hybrid vehicles offer lower costs while still meeting fuel consumption regulations.

[0003] However, for battery packs in hybrid electric vehicles (HEVs), high power output is required when the battery is low. Currently, the best solution is ternary lithium batteries. However, the materials used in ternary lithium batteries, such as nickel, cobalt, manganese, and lithium carbonate, are scarce. As battery demand continues to rise, lithium battery prices are also rising sharply. The pressure of rising costs is not conducive to the promotion of new energy vehicles. Therefore, dedicated batteries that can meet the needs of HEVs and significantly reduce costs have become the main trend in battery development. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0005] This application provides a sodium-ion battery positive electrode sheet, which includes: a positive electrode current collector and a positive electrode active material disposed on the surface of the positive electrode current collector, wherein the positive electrode active material includes an intercalation-deintercalation type positive electrode material and an adsorption type positive electrode material;

[0006] The amount of positive active material used on the surface of the positive current collector is 0.2g to 0.8g per square decimeter;

[0007] The weight ratio of the deintercalation-type cathode material to the adsorption-type cathode material is (65 to 85):(30 to 10).

[0008] In one embodiment provided in this application, the deintercalation-intercalation cathode material is selected from any one or more of layered sodium ion compounds, polyanionic sodium ion compounds, Prussian blue compounds, and carbonyl compounds;

[0009] In one embodiment provided in this application, the interlayer spacing of the deintercalation cathode material is 0.37 nm to 0.6 nm.

[0010] In one embodiment provided in this application, the deintercalation-deintercalation cathode material is selected from Na. xMO2 (M is selected from any one or more of Co, Fe, Mn and Ni), perylenetetracarboxylic dianhydride (PTCDA), sodium vanadium fluorophosphate and Na2Fe2(SO4)3 are all selected from one or more of these.

[0011] In one embodiment provided in this application, the adsorption-type positive electrode material is selected from any one or two of activated carbon and graphene.

[0012] In one embodiment provided in this application, the sodium-ion battery positive electrode sheet includes: a positive electrode current collector, a positive electrode active material disposed on the surface of the positive electrode current collector, and an additive disposed on the surface of the positive electrode current collector to improve the conductivity of the positive electrode.

[0013] In one embodiment provided in this application, the additive for improving the conductivity of the positive electrode is selected from any one or more of conductive carbon black, conductive carbon fiber, and conductive carbon nanotubes.

[0014] In one embodiment provided in this application, the amount of the additive for improving the conductivity of the positive electrode current collector surface is 0.03g to 0.06g per square decimeter.

[0015] In one embodiment provided in this application, the surface of the positive current collector further includes a positive electrode adhesive, and the amount of the positive electrode adhesive on the surface of the positive current collector is 0.01g to 0.03g per square decimeter; the positive electrode adhesive is selected from any one or more of styrene-butadiene rubber latex, carboxymethyl cellulose and polyvinylidene fluoride.

[0016] In another aspect, this application provides a sodium-ion battery, including a negative electrode, an electrolyte, and a separator, as well as the aforementioned sodium-ion battery positive electrode.

[0017] In one embodiment provided in this application, the concentration of the additive in the electrolyte is from 0.5 mol / L to 3 mol / L;

[0018] In one embodiment provided in this application, the additives in the electrolyte are selected from any one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, phosphorus pentafluoride, and hydrofluoric acid.

[0019] In one embodiment of this application, the electrolyte is a sodium ion electrolyte; in another embodiment, the electrolyte is an organic sodium salt electrolyte; in yet another embodiment, the electrolyte is a sodium hexafluorophosphate electrolyte.

[0020] In one embodiment provided in this application, the negative electrode sheet includes a negative electrode current collector and a negative electrode layered material disposed on the surface of the negative electrode current collector.

[0021] In one embodiment provided in this application, the negative electrode sheet includes a negative electrode current collector, a negative electrode layered material disposed on the surface of the negative electrode current collector, and an additive for improving the conductivity of the negative electrode disposed on the surface of the negative electrode current collector.

[0022] In one embodiment provided in this application, the amount of negative electrode layered material on the surface of the negative electrode current collector is 0.2g to 0.5g per square decimeter.

[0023] In one embodiment provided in this application, the amount of additive for improving the conductivity of the negative electrode on the surface of the negative electrode current collector is 0.03g to 0.06g per square decimeter.

[0024] In one embodiment provided in this application, the surface of the negative electrode current collector further includes a negative electrode adhesive, and the amount of negative electrode adhesive on the surface of the negative electrode current collector is 0.01g to 0.03g per square decimeter; the negative electrode adhesive is selected from any one or more of styrene-butadiene rubber latex, carboxymethyl cellulose and polyvinylidene fluoride.

[0025] In one embodiment provided in this application, the negative electrode layered material is a stable low-potential layered material with a layered structure, and the interlayer spacing of the negative electrode layered material is 0.41 nm to 0.51 nm.

[0026] In one embodiment provided in this application, the potential of the negative electrode layered material is below 0.2V.

[0027] In one embodiment provided in this application, the pore size of the diaphragm is 0.37 nm to 1000 nm; in another embodiment provided in this application, the pore size of the diaphragm is 0.4 nm to 0.8 nm.

[0028] In one embodiment provided in this application, the negative electrode layered material is selected from any one or more of carbon-based materials, titanium-based materials, sodium alloy compounds, and transition metal materials.

[0029] In one embodiment provided in this application, the negative electrode layered material is selected from any one or more of soft carbon, hard carbon, graphene, titanium dioxide, titanium spinel, sodium peptide, CNs and MxOy (M = Co, Fe, Cu, Ni).

[0030] In one embodiment provided in this application, the additive for improving the conductivity of the negative electrode current collector surface is selected from any one or more of conductive carbon black, conductive carbon fiber, and conductive carbon nanotubes.

[0031] In one embodiment of this application, the negative electrode current collector and the positive electrode current collector are each independently selected from highly conductive and non-oxidizing metallic materials; in one embodiment of this application, the conductivity of the highly conductive and non-oxidizing metallic material is ≤5×10⁻⁶. 8 Ωm, the potential of the material is ≤-0.5V.

[0032] In one embodiment provided in this application, the negative current collector and the positive current collector are each independently selected from any one or two of aluminum foil and silver foil;

[0033] In one embodiment provided in this application, the pore size of the separator is a battery separator with a pore size of 0.37 nm to 0.6 nm; preferably, the material of the separator is selected from any one or more of glass fiber filter paper, organic polymer nonwoven fabric, polyolefin composite separator, and perfluorosulfonic acid membrane.

[0034] Furthermore, this application provides the application of the aforementioned sodium-ion battery in high-power batteries. The discharge rate of the battery can be from 30C to 100C; the discharge power of the battery can be from 40kW to 150kW.

[0035] On the other hand, this application provides the above-mentioned application of sodium-ion batteries in hybrid electric vehicles.

[0036] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application may be realized and obtained by means of the methods described in the description. Attached Figure Description

[0037] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0038] Figure 1 This is a schematic diagram of a ternary lithium battery in the prior art.

[0039] Figure 2 This is a schematic diagram of a sodium-ion battery according to Embodiment 1 of this application.

[0040] Figure 3 This is a schematic diagram comparing the discharge power of the sodium-ion battery and the ternary lithium battery prepared in Example 1 of this application.

[0041] Figure 4 This is a schematic diagram showing the relationship between the weight ratio of activated carbon in the positive electrode active material and the energy density.

[0042] Figure 5This is a schematic diagram showing the relationship between the weight ratio of activated carbon in the positive electrode active material and the power density.

[0043] Reference numerals: 1. Positive electrode; 2. Negative electrode; 3. Separator; 4. Electrolyte; 5. Deintercalation type positive electrode material; 6. Adsorption type positive electrode material; 7. Positive electrode current collector; 8. Negative electrode current collector; 9. Negative electrode layered material. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application are described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0045] The embodiments of this application provide a hybrid sodium-ion battery structure as follows: Figure 2 As shown: the positive electrode 1 is mainly composed of a mixture of deintercalation type positive electrode material 5 and adsorption type positive electrode material 6 and is attached to the positive electrode current collector 7. The negative electrode 2 is mainly composed of negative electrode layered material 9 and is attached to the negative electrode current collector 8. There is an electrolyte 4 and a separator 3 between the positive electrode 1 and the negative electrode 2.

[0046] In the embodiments of this application, the optional preparation method of the sodium-ion battery can be carried out in accordance with the process flow of paragraphs 0037 to 0047 in Chinese Patent CN110048071A.

[0047] Example 1

[0048] Example 1 provides a sodium-ion battery positive electrode sheet comprising a positive current collector (aluminum foil with a thickness of 15 μm, 0.72 μm...). 2 The method comprises: positive electrode active material, positive electrode binder, and additives to improve conductivity; the positive electrode active material, the positive electrode binder, and the additives to improve conductivity are mixed evenly and then coated on one side of the positive electrode current collector. The amount of positive electrode active material on the surface of the positive electrode current collector is 0.2g to 0.8g per square decimeter. The positive electrode active material includes adsorption-type positive electrode material and deintercalation-type positive electrode material, and the weight ratio of the deintercalation-type positive electrode material to the adsorption-type positive electrode material is (65 to 85):(30 to 10). The sodium-ion battery provided in this embodiment combines the advantages of double-layer supercapacitors to meet the discharge power requirements of HEVs and solve the problems of low energy density and poor self-discharge of double-layer supercapacitors.

[0049] The interlayer spacing of the deintercalation-intercalation type cathode material ranges from 0.37 nm to 0.6 nm. The deintercalation-intercalation type cathode material can be selected as a layered sodium ion compound Na₂Fe₂(SO₄)₃, with an interlayer spacing ranging from 0.37 nm to 0.51 nm. The adsorption type cathode material can be selected as activated carbon for batteries (0.72 nm). 2The positive electrode current collector corresponds to 0.0069 kg of material. The weight ratio of the deintercalation type positive electrode material to the adsorption type positive electrode material is 85:15. The amount of the additive for improving the conductivity of the positive electrode on the surface of the positive electrode current collector is 0.03 g to 0.06 g per square decimeter. The additive for improving the conductivity of the positive electrode current collector includes conductive carbon nanotubes (CNTs) (0.72 μm). 2 The positive electrode current collector corresponds to 0.0005 kg of material) and conductive carbon black SPli (0.72 m). 2 The positive electrode current collector corresponds to 0.0033 kg of material. The amount of positive electrode adhesive on the surface of the positive electrode current collector is 0.01 g to 0.03 g per square decimeter; the positive electrode adhesive can be polyvinylidene fluoride (PVDF) (0.72 m). 2 The positive current collector corresponds to 0.0013 kg of material.

[0050] The negative electrode of the sodium-ion battery provided in Example 1 includes a negative electrode current collector (aluminum foil with a thickness of 9 μm, 0.72 m). 2 The anode material comprises a negative electrode layered material, a negative electrode binder, and additives to improve conductivity; the negative electrode material and the negative electrode binder are mixed evenly and then coated on one side of the negative electrode current collector. The amount of negative electrode layered material on the surface of the negative electrode current collector is 0.2g to 0.5g per square decimeter. The negative electrode layered material includes soft carbon (0.72m... 2 The negative electrode current collector corresponds to 0.025 kg of material; the interlayer spacing of the negative electrode layered material is 0.41 nm to 0.51 nm, and the potential of the negative electrode layered material is below 0.2 V. The additive for improving conductivity on the surface of the negative electrode current collector is used at an amount of 0.03 g to 0.06 g per square decimeter; the additive for improving conductivity on the surface of the negative electrode current collector is selected from conductive carbon black SPli (0.72 μm). 2 The negative electrode current collector corresponds to 0.0033 kg of material) conductive carbon fiber VGCF (0.72 m 2 The negative electrode current collector corresponds to 0.0005 kg of material; the amount of negative electrode adhesive used is 0.01 g to 0.03 g per square decimeter, and the negative electrode adhesive is selected from any one or more of styrene-butadiene rubber latex, carboxymethyl cellulose, and polyvinylidene fluoride. In this embodiment, the negative electrode adhesive is styrene-butadiene rubber latex SBR BM-451B (0.72 m³). 2 The negative electrode current collector corresponds to 0.0008 kg of material and carboxymethyl cellulose CMC2200 (0.72 m). 2The negative electrode current collector corresponds to 0.0008 kg of material. Aluminum foil is used for both the positive and negative electrode current collectors, reducing the battery's dependence on precious metal materials. Sodium ions are abundant in nature and have low cost, which can significantly reduce battery costs by more than 50%, making it more conducive to the promotion of hybrid vehicles.

[0051] The separator for the sodium-ion battery provided in Example 1 is glass fiber filter paper, which can be purchased from Henan Huiqiang New Energy Materials Technology Co., Ltd., with a thickness of 16μm and a diameter of 0.737m. 2 The pore size of the diaphragm is from 0.37 nm to 1000 nm, preferably from 0.4 nm to 0.8 nm. In this embodiment, the pore size of the diaphragm is 0.4 nm.

[0052] The concentration of the additive in the electrolyte is from 0.5 mol / L to 3 mol / L; optionally, the additive in the electrolyte is selected from any one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, phosphorus pentafluoride, and hydrofluoric acid; optionally, the electrolyte is a sodium ion electrolyte, preferably, the electrolyte is an organic sodium salt electrolyte, and more preferably, the electrolyte is a sodium hexafluorophosphate electrolyte. The electrolyte of the sodium ion battery provided in Example 1 is a sodium hexafluorophosphate electrolyte with added ethylene carbonate, which can be purchased from Do-Fluoride Chemicals Co., Ltd.; the corresponding amount of sodium hexafluorophosphate electrolyte in this battery is 0.035 kg, and the concentration of ethylene carbonate in the electrolyte is 2 mol / L.

[0053] Based on Example 1, the proportion of adsorbed positive electrode material (activated carbon) in the positive electrode active material was changed; the proportion of adsorbed positive electrode active material started from 0%, with 5% increments, up to 100%; battery performance was tested. The discharge power at 50% SOC for 10 seconds at room temperature was tested. The test results are as follows... Figure 3 , Figure 4 and Figure 5 As shown.

[0054] from Figure 3 As can be seen, under the same SOC, the sodium-ion battery provided in Example 1 of this application has a discharge capacity close to that of current ternary lithium batteries, meeting the needs of HEV models. It provides HEVs with multiple functions such as low-speed pure electric driving, acceleration assistance, and energy recovery while achieving low cost.

[0055] from Figure 4 and Figure 5As can be seen, the sodium-ion battery provided in Example 1 of this application maintains a power density of 2 kW / kg to 3.5 kW / kg and a battery energy density of 40 Wh / kg to 80 Wh / kg. This meets the requirements for use in HEV battery packs.

[0056] The sodium-ion battery provided in this application reduces the battery's dependence on precious metal materials. Sodium ions are abundant in nature and have low cost, which can significantly reduce battery costs by more than 50%, making it more conducive to the promotion of hybrid vehicles.

[0057] The sodium-ion battery provided in this application comprises both adsorption-type and deintercalation-type positive electrode materials, combining the advantages of double-layer supercapacitors to meet the discharge power requirements of HEVs and address the issues of low energy density and poor self-discharge in double-layer supercapacitors. The sodium-ion battery positive electrode material provided in this application exhibits better self-discharge performance compared to purely adsorption-type electrodes (requiring less than 5% for HEV batteries).

Claims

1. A sodium-ion battery positive electrode, characterized in that, The sodium-ion battery positive electrode sheet includes: a positive electrode current collector and a positive electrode active material disposed on the surface of the positive electrode current collector; The positive electrode active material is composed of a deintercalation positive electrode material and an adsorption positive electrode material; The amount of positive active material used on the surface of the positive current collector is 0.2g to 0.8g per square decimeter; The weight ratio of the deintercalation-type positive electrode material to the adsorption-type positive electrode material is (65 to 85):(30 to 10); The interlayer spacing of the deintercalation-deintercalation cathode material is 0.37 nm to 0.6 nm; The deintercalation cathode material is selected from Na. x MO2, perylenetetracarboxylic acid dianhydride, sodium vanadium fluorophosphate, and Na2Fe2(SO4)3 are selected from any one or more of Co, Fe, Mn, and Ni; The adsorption-type positive electrode material is activated carbon.

2. The sodium-ion battery positive electrode sheet according to claim 1, characterized in that, The sodium-ion battery positive electrode sheet includes: a positive electrode current collector, a positive electrode active material disposed on the surface of the positive electrode current collector, an additive for improving the conductivity of the positive electrode disposed on the surface of the positive electrode current collector, and a positive electrode binder. The additives for improving the conductivity of the positive electrode are selected from any one or more of conductive carbon black, conductive carbon fiber, and conductive carbon nanotubes. The amount of the additive for improving the conductivity of the positive electrode current collector surface is 0.03g to 0.06g per square decimeter; The positive electrode adhesive is selected from any one or more of styrene-butadiene rubber latex, carboxymethyl cellulose, and polyvinylidene fluoride. The amount of positive electrode adhesive used on the surface of the positive electrode current collector is 0.01g to 0.03g per square decimeter.

3. A sodium-ion battery, comprising a negative electrode, an electrolyte, and a separator, characterized in that, It also includes the sodium-ion battery positive electrode sheet according to any one of claims 1 to 2.

4. The sodium-ion battery according to claim 3, characterized in that, The concentration of the additive in the electrolyte is from 0.5 mol / L to 3 mol / L; The additives in the electrolyte are selected from any one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, phosphorus pentafluoride, and hydrofluoric acid. The electrolyte is a sodium ion electrolyte; The negative electrode sheet includes a negative electrode current collector, a negative electrode layered material disposed on the surface of the negative electrode current collector, and a negative electrode adhesive; The negative electrode sheet includes a negative electrode current collector, a negative electrode layered material disposed on the surface of the negative electrode current collector, and an additive for improving the conductivity of the negative electrode disposed on the surface of the negative electrode current collector. The amount of additive used to improve the conductivity of the negative electrode on the surface of the negative electrode current collector is 0.03g to 0.06g per square decimeter. The negative electrode adhesive is selected from any one or more of styrene-butadiene rubber latex, carboxymethyl cellulose, and polyvinylidene fluoride. The amount of negative electrode adhesive used on the surface of the negative electrode current collector is 0.01g to 0.03g per square decimeter.

5. The sodium-ion battery according to claim 4, characterized in that, The electrolyte is an organic sodium salt electrolyte.

6. The sodium-ion battery according to claim 5, characterized in that, The electrolyte is sodium hexafluorophosphate electrolyte.

7. The sodium-ion battery according to any one of claims 3 to 6, characterized in that, The amount of negative electrode layered material used on the surface of the negative electrode current collector is 0.2g to 0.5g per square decimeter; The negative electrode layered material is a stable low-potential layered material with a layered structure, and the interlayer spacing of the negative electrode layered material is 0.41 nm to 0.51 nm. The potential of the negative electrode layered material is below 0.2V; The pore size of the diaphragm is from 0.37 nm to 1000 nm.

8. The sodium-ion battery according to claim 7, characterized in that, The pore size of the diaphragm is 0.4 nm to 0.8 nm.

9. The sodium-ion battery according to any one of claims 3 to 6, characterized in that, The negative electrode layered material is selected from any one or more of carbon-based materials, titanium-based materials, sodium alloy compounds, and transition metal materials; The additives for improving the conductivity of the negative electrode current collector surface are selected from any one or more of conductive carbon black, conductive carbon fiber, and conductive carbon nanotubes. The negative electrode current collector and the positive electrode current collector are each independently selected from highly conductive and non-oxidizing metal materials; The electrical conductivity of the metallic material is ≤5×10⁻⁶. 8 Ωm, the potential of the metallic material is ≤-0.5V; The separator has a pore size of 0.37 nm to 0.6 nm.

10. The sodium-ion battery according to claim 9, characterized in that, The negative electrode layered material is selected from soft carbon, hard carbon, graphene, titanium dioxide, titanium-based spinel, CNs, and A. x O y Any one or more of the following, where A is Co, Fe, Cu, or Ni; The negative electrode current collector and the positive electrode current collector are each independently selected from any one or two of aluminum foil and silver foil; The membrane material is selected from any one or more of glass fiber filter paper, organic polymer nonwoven fabric, polyolefin composite membrane, and perfluorosulfonic acid membrane.

11. The application of the sodium-ion battery according to any one of claims 3 to 10 in high-power batteries; The sodium-ion battery has a discharge rate of 30C to 100C.

12. The application of the sodium-ion battery according to any one of claims 3 to 10 in a hybrid electric vehicle.

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