Conductive agent and preparation method thereof, pole piece, battery, battery pack and electric equipment

Abstract

The invention discloses a conductive agent and a preparation method and application thereof, and belongs to the technical field of lithium batteries, and the conductive agent is characterized by comprising a porous carbon-based nano material and metal peroxide nano particles in pores of the porous carbon-based nano material. The conductive agent provided by the invention can be applied to preparation of lithium battery positive electrode slurry. The metal peroxide nanoparticles in the conductive agent provided by the invention can react with trace water in the battery to generate O2, and in the SEI film generation process, the O2 can accelerate the generation rate of Li2O, finally increase the content of the Li2O component and reduce the direct current impedance of the battery, so that the rate performance of the battery is improved, and meanwhile, water removal and acid inhibition are realized, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and specifically to a conductive agent and a preparation method thereof, an electrode, a battery, a battery pack, and electrical equipment. Background Art

[0002] In lithium-ion batteries, the intrinsic properties of the solid electrolyte membrane (SEI) directly influence battery performance. Numerous literature reports indicate that the Li2O component in the SEI membrane contributes to improved battery rate capability and lifespan. Therefore, increasing the Li2O content in the SEI membrane is an effective means of improving battery performance.

[0003] However, the SEI film formation mechanism and the structure-activity relationship between component ratios and electrolyte composition remain unclear. Furthermore, the SEI film breaks down and regenerates during battery charge and discharge, leading to dynamic compositional changes. Therefore, controlling the SEI film to maintain a high Li2O content during battery charge and discharge is extremely difficult. Currently, the mainstream approach to constructing a Li2O-rich SEI film is to directly add Li2O to the negative electrode material. However, this approach only ensures that the SEI film during battery formation is rich in Li2O, but cannot guarantee that the SEI film generated during charge and discharge will also be rich in Li2O. Furthermore, this approach requires high-precision experimental control, which is prohibitively expensive and difficult to implement in engineering applications. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present application provides a conductive agent and its preparation method, electrode, battery, battery pack and electrical equipment to reduce the DC impedance of the battery, thereby improving the battery rate performance, while removing water and inhibiting acid, thereby extending the battery life.

[0005] In the first aspect, the present application provides a conductive agent comprising a porous carbon-based nanomaterial and metal peroxide nanoparticles in its pores. The metal peroxide nanoparticles can react with trace water inside the battery to generate O2. During the formation of the SEI film, O2 can accelerate the generation rate of Li2O, ultimately increasing the content of Li2O in the SEI film, which can significantly reduce the DC impedance of the battery and thus improve the rate performance. Since the water inside the electrode will continue to escape as the structure changes during the battery cycle, the metal peroxide nanoparticles will have the ability to release oxygen sustainably. In addition to releasing oxygen, the metal peroxide nanoparticles will react with the water inside the battery, so they also have the function of removing water and inhibiting acid, which can improve the battery life.

[0006] Optionally, the metal peroxide nanoparticles include at least one of alkali metal peroxide nanoparticles and alkaline earth metal peroxide nanoparticles.

[0007] Optionally, the average pore size of the porous carbon-based nanomaterial is 50nm-100nm.

[0008] Optionally, the porous carbon-based nanomaterial includes at least one of acetylene black, conductive carbon black (Super-P), carbon nanotubes and graphene.

[0009] Optionally, the alkali metal peroxide nanoparticles include at least one of Li2O2, Na2O2, K2O2, Rb2O2, and Cs2O2.

[0010] Optionally, the alkaline earth metal peroxide nanoparticles include at least one of BeO2, MgO2, CaO2, SrO2, and BaO2.

[0011] Optionally, based on the total mass of the conductive agent, the content of the metal peroxide nanoparticles in the conductive agent is 1% to 45%.

[0012] In a second aspect, the present application provides a method for preparing a conductive agent, which is simple to operate and can prepare the conductive agent, comprising:

[0013] S1: mixing porous carbon-based nanomaterials, metal salts, surfactants, and solvents;

[0014] S2 adjusts the pH to 7-8 and stirs to obtain a suspension;

[0015] S3: adding an H2O2 aqueous solution to the suspension obtained in step S2, and then adjusting the pH value to 9-10, and reacting to obtain the conductive agent.

[0016] Optionally, the metal in the metal salt may be at least one of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba.

[0017] Optionally, the acid radical in the metal salt may be Cl - , NO 3- , SO4 2- , SO2(CF3)2 2- At least one of them.

[0018] Optionally, the mass ratio of the porous carbon-based nanomaterial to the metal salt is 1:0.5 to 1:2.5.

[0019] Optionally, the surfactant includes at least one of polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, dextran, and diethylene glycol dimethyl ether.

[0020] In a third aspect, the present application further provides a pole piece comprising the conductive agent of the first aspect or a conductive agent produced using the conductive agent preparation method of the second aspect.

[0021] In a fourth aspect, the present application also provides a battery comprising the electrode according to the third aspect.

[0022] In a fifth aspect, the present application also provides a battery pack comprising at least two batteries according to the fourth aspect.

[0023] In a sixth aspect, the present application further provides an electrical device comprising the battery of the fourth aspect or the battery pack of the fifth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a scanning electron microscope image of Example 1;

[0025] Figure 2 The test results of Li2O content in the SEI films of Example 1, Example 2, and Comparative Example 1 after formation and high-temperature cycling are shown. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] The present application provides a conductive agent comprising a porous carbon-based nanomaterial and metal peroxide nanoparticles in its pores. The pores of the porous carbon-based nanomaterial can provide sites for the generation of metal peroxide nanoparticles, which can react with trace water inside the battery to generate O2. During the formation of the SEI film, O2 can accelerate the generation rate of Li2O, and ultimately increase the content of Li2O in the SEI film, which can significantly reduce the DC impedance of the battery and thus improve the rate performance. Since the water inside the electrode will continue to escape as the structure changes during the battery cycle, the metal peroxide nanoparticles will have the ability to release oxygen sustainably. In addition to releasing oxygen, the metal peroxide nanoparticles will react with the water inside the battery, so they also have the function of removing water and inhibiting acid, which can increase the battery life.

[0028] In one embodiment of the present application, the average pore size of the porous carbon-based nanomaterial is 50nm-100nm, and the average pore size is measured using the small-angle X-ray scattering (SAXS) method. By measuring the scattering intensity of X-rays in the carbon material, the pore size distribution function can be obtained. The product of the pore size distribution function and the pore size is integrated over the entire pore size range, and then divided by the integral of the pore size distribution function over the entire pore size range to obtain the average pore size. The appropriate pore size can ensure that the metal peroxide nanoparticles are generated in the pores and prevent the metal peroxide nanoparticles from being generated outside the porous carbon-based nanomaterial, which is conducive to controlling the particle size of the metal peroxide nanoparticles. At the same time, the appropriate pore size can ensure the conductivity of the conductive agent, thereby ensuring the charge and discharge performance of the battery.

[0029] In one embodiment of the present application, the porous carbon-based nanomaterial includes, but is not limited to, at least one of acetylene black, conductive carbon black, carbon nanotubes, and graphene. Such porous carbon-based nanomaterials facilitate the adsorption of metal peroxide nanoparticles, increase the number of sites for metal peroxide nanoparticle generation, make it easier to obtain metal peroxide nanoparticles, and prevent them from agglomerating. Furthermore, they have high electronic conductivity and a high specific surface area, reducing the battery's DC impedance, thereby improving its rate performance, while also removing water and inhibiting acid, thereby extending its life. In yet another embodiment of the present application, the porous carbon-based nanomaterial can be conductive carbon black or graphene, which further reduces the battery's DC impedance, thereby improving its rate performance, while also removing water and inhibiting acid, thereby extending its life.

[0030] In one embodiment of the present application, the metal peroxide nanoparticles in the conductive agent include at least one of alkali metal peroxide nanoparticles and alkaline earth metal peroxide nanoparticles. Specifically, the metal peroxide nanoparticles include at least one of Li2O2, Na2O2, K2O2, Rb2O2, Cs2O2, BeO2, MgO2, CaO2, SrO2, and BaO2. After the alkali metal peroxide nanoparticles and alkaline earth metal peroxide nanoparticles release oxygen, metal ions are less likely to deposit at the negative electrode and form dendrites, thereby avoiding battery degradation and safety risks, thereby improving battery life. In another embodiment of the present application, the metal peroxide nanoparticles in the conductive agent can be at least one of Li2O2 and CaO2, which can better avoid battery degradation and safety risks, thereby further improving battery life.

[0031] In one embodiment of the present application, the content of metal peroxide nanoparticles in the conductive agent is 1% to 45%. This helps balance the conductivity of the conductive agent and the oxygen release rate of the metal peroxide, can control the oxygen release rate, ensure that the SEI film is continuously replenished with Li2O, improve battery rate performance, and extend battery life. Specifically, the content of metal peroxide nanoparticles in the conductive agent can be, but is not limited to, 1%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 28%, 30%, 33%, 35%, 37%, 45%, and any two thereof. In another embodiment of the present application, the content of at least one of the metal peroxide nanoparticles in the conductive agent can be 9% to 22%, which can better control the oxygen release rate, ensure that the SEI film is continuously replenished with Li2O, improve battery rate performance, and extend battery life.

[0032] The present application also provides a method for preparing a conductive agent, comprising: mixing a porous carbon-based nanomaterial, a metal salt, a surfactant, and a solvent, adjusting the pH to 7-8, adding an aqueous H2O2 solution after stirring, adjusting the pH to 9-10, filtering, and drying to obtain the conductive agent. The above-mentioned conductive agent preparation method is simple, environmentally friendly, and the solvent can be recycled.

[0033] In one embodiment of the present application, the metal in the metal salt includes at least one of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba, and metal peroxide nanoparticles in the conductive agent can be prepared. In another embodiment of the present application, the metal in the metal salt can be at least one of Li and Ca, and at least one of Li2O2 and CaO2 can be prepared.

[0034] In one embodiment of the present application, the acid radical of the metal salt is Cl - 、NO 3- 、SO4 2- 、SO2(CF3)2 2- The acid radical residue of the metal salt is low, which has little harm to the battery. In another embodiment of the present application, the acid radical in the metal salt can be Cl - , SO4 2- , which can further reduce the harm to the battery.

[0035] In one embodiment of the present application, the solvent includes but is not limited to water.

[0036] In one embodiment of the present application, the mass ratio of the porous carbon-based nanomaterial and the metal salt is set to 1:0.5 to 1:25, which is beneficial to regulating the content of the metal peroxide nanoparticles in the product, and can control the oxygen release rate, ensure that the SEI film is continuously replenished with Li2O, reduce the DC impedance of the battery, and thus improve the battery rate performance, while removing water and suppressing acid, thereby extending the battery life. Specifically, the mass ratio of the porous carbon-based nanomaterial and the metal salt can be, but is not limited to, 1:0.5, 1:0.66, 1:0.77, 1:1, 1:1.3, 1:1.6, 1:1.66, 1:1.8, 1:2, 1:2.5, and the range of any two thereof. In another embodiment of the present application, the mass ratio of the porous carbon-based nanomaterial and the metal salt can be 1:0.75 to 1:1, which can better control the oxygen release rate, ensure that the SEI film is continuously replenished with Li2O, better reduce the DC impedance of the battery, thereby improving the battery rate performance, while removing water and suppressing acid, thereby extending the battery life.

[0037] In one embodiment of the present application, the surfactant includes at least one of polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, dextran, and diethylene glycol dimethyl ether. These surfactants are readily soluble in water, are used in relatively small amounts, and are harmless to battery performance. Alternatively, the surfactant may be polyvinyl pyrrolidone, dextran, or diethylene glycol dimethyl ether.

[0038] This embodiment further provides an electrode sheet, comprising a current collector and the conductive agent, or a conductive agent prepared using the conductive agent preparation method. The beneficial effects of this embodiment are as shown in the above embodiment.

[0039] The present invention also provides a battery comprising the aforementioned electrode sheets. A positive electrode sheet, a separator, and a negative electrode sheet are stacked in sequence, and then a battery cell is obtained through a lamination or winding process. The battery is then baked, injected, formed, and packaged to obtain the battery.

[0040] The present application also provides a battery pack. In some embodiments, the battery pack is assembled from battery cells. The battery pack may contain one or more battery cells, which may be assembled in parallel or in series. The specific number and assembly method can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0041] There is no special restriction on the specific type of battery in this application. For example, from the perspective of shape, the battery includes but is not limited to square shell batteries, soft pack batteries and cylindrical batteries, etc., and this application does not impose any special restrictions. From the perspective of the pole core structure, the pole core of the battery can be a wound pole core (that is, the positive electrode sheet, the negative electrode sheet and the separator are stacked and arranged, and then the pole core is made by a winding process), or it can be a laminated pole core (that is, multiple positive electrode sheets, negative electrode sheets and separators are stacked to form a pole core). The outer shell can be a hard shell (such as a steel shell, a hard plastic shell, etc.), or a soft shell (such as an aluminum-plastic film, a bag-type soft shell, etc.). This application does not impose any special restrictions.

[0042] An embodiment of the present application further provides an electrical device comprising the above-mentioned battery or battery pack. The electrical device has advantages corresponding to the above-mentioned electrode additives, which will not be described in detail.

[0043] The electrical equipment in the embodiments of the present application can be conventional electrical equipment in this field, such as power equipment (such as electric vehicles, electric cars), electronic equipment (such as mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without special restrictions.

[0044] The present application is further described in detail below using several specific experiments as examples and in conjunction with the accompanying drawings.

[0045] Example 1

[0046] Conductive agent preparation, steps are as follows:

[0047] Step 1) First, 5g LiCl and 50g CaSO4 were added to 6L water in sequence and fully dissolved. Then, 50g conductive carbon black (Super-P) was added to the above solution and stirred evenly. Then, 500mL polyethylene glycol was added and stirred evenly.

[0048] Step 2) Using aqueous ammonia, the pH of the solution obtained in step 1) is adjusted to 7 to obtain a suspension.

[0049] Step 3) The suspension obtained in step 2) was stirred in an ice bath for 4 h and then heated at 30 mL min -1 A 30% molar fraction of H₂O₂ aqueous solution was added dropwise at a rate of 2 L while stirring for 4 hours to obtain a mixed solution. Ammonia was added to the resulting mixed solution to adjust the pH to 10. After the reaction, the solid was filtered, rinsed with ultrapure water and then ethanol, and then dried in a vacuum oven at 100°C to obtain 56.2 g of Li₂O₂ / CaO₂@SP conductive agent. The metal ion concentration was measured using ICP-OES (inductively coupled plasma optical emission spectrometry), revealing a combined mass percentage of 12.1% for Li₂O₂ and CaO₂ in the conductive agent.

[0050] Preparation of lithium iron phosphate (LiFePO4, LFP) graphite soft pack battery:

[0051] Positive electrode slurry formula: The mass ratio of LFP main material, Li2O2 / CaO2@SP, and PVDF binder is 95:2.8:2.2, and the solid content of the slurry is 61.5%. The slurry and electrode are prepared according to the following steps:

[0052] 1) PVDF and NMP were mixed and stirred to prepare a glue solution;

[0053] 2) Add Li2O2 / CaO2@SP to the adhesive solution, stir and add NMP to assist solid dispersion, and stir and disperse the Li2O2 / CaO2@SP evenly to obtain a conductive adhesive solution;

[0054] 3) Add the LFP main material to the conductive glue solution in step 2) by adding 50% each time and stirring until it is evenly dispersed; then vacuum and stir to obtain the positive electrode slurry;

[0055] 4) Coating process: The positive electrode slurry is rolled onto the surface of the aluminum foil, dried, and then rolled to obtain the positive electrode sheet.

[0056] A natural graphite negative electrode was designed and fabricated with an N / P ratio of 1:1. The negative electrode slurry formula consisted of natural graphite, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and SuperP conductive agent in a mass ratio of 94:1.8:2.2:2, with a slurry solids content of 62.6%. The slurry and electrode were prepared as follows:

[0057] 1) Add natural graphite and SuperP into a high-speed mixer and knead them.

[0058] 2) Add CMC and stir at low speed to make CMC evenly distributed in the mixture.

[0059] 3) Finally, add SBR emulsion, stir and fully disperse the components to obtain negative electrode slurry.

[0060] 4) Coating process: The negative electrode slurry is rolled onto the surface of the aluminum foil, dried, and then rolled to obtain the negative electrode sheet.

[0061] Soft pack battery production:

[0062] 1) Cut the positive and negative electrode sheets into 6cm x 7cm pieces and use a lamination process to produce a three-positive, four-negative soft-pack battery. Use a 13μm PE separator, a common carbonate electrolyte with a mass ratio of DMC:EMC:EC = 1:1:1, and LiPF6 at a concentration of 1 mol / L.

[0063] 2) At 25° C., the obtained soft-pack battery was charged with a current of 0.2 C for 3 h, then charged to 3.8 V at 0.5 C, and then discharged to 2 V at 0.5 C. This cycle was repeated three times to obtain a formed battery.

[0064] Example 2

[0065] This embodiment is basically the same as the first embodiment, except that:

[0066] In the conductive agent preparation method of this embodiment, step 1) 50g of CaSO4 is added to 6L of water to fully dissolve, then 50g of conductive carbon black (Super-P) is added to the above solution and stirred evenly, and then 500mL of polyethylene glycol is added and stirred evenly.

[0067] Finally, 55.2 g of CaO2@SP conductive agent was obtained, in which the mass percentage of CaO2 was 9.4%.

[0068] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0069] Example 3

[0070] This embodiment is basically the same as the first embodiment, except that:

[0071] In the conductive agent preparation method of this embodiment, step 1) 20g of LiCl was added to 6L of water to fully dissolve, and then 50g of conductive carbon black (Super-P) was added to the above solution and stirred evenly, and then 500mL of polyethylene glycol was added and stirred evenly.

[0072] Finally, 51.6 g of Li2O2@SP conductive agent was obtained, in which the mass percentage of Li2O2 was 3.1%.

[0073] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0074] Example 4

[0075] This embodiment is basically the same as the first embodiment, except that:

[0076] In the conductive agent preparation method of this embodiment, step 1) 65g of CaSO4 is added to 6L of water to fully dissolve, then 50g of conductive carbon black (Super-P) is added to the above solution and stirred evenly, and then 500mL of polyethylene glycol is added and stirred evenly.

[0077] Finally, 63.5 g of CaO2@SP conductive agent was obtained, in which the mass percentage of CaO2 was 21.2%.

[0078] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0079] Example 5

[0080] This embodiment is basically the same as the first embodiment, except that:

[0081] In the conductive agent preparation method of this embodiment, step 1) 100g of CaSO4 is added to 6L of water to fully dissolve, then 50g of conductive carbon black (Super-P) is added to the above solution and stirred evenly, and then 500mL of polyethylene glycol is added and stirred evenly.

[0082] Finally, 89.4 g of CaO2@SP conductive agent was obtained, in which the mass percentage of CaO2 was 44.1%.

[0083] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0084] Example 6

[0085] This embodiment is basically the same as the first embodiment, except that:

[0086] In the conductive agent preparation method of this embodiment, step 1) 20g of CaSO4 is added to 6L of water to fully dissolve, then 50g of conductive carbon black (Super-P) is added to the above solution and stirred evenly, and then 500mL of polyethylene glycol is added and stirred evenly.

[0087] Finally, 50.7 g of CaO2@SP conductive agent was obtained, in which the mass percentage of CaO2 was 1.4%.

[0088] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0089] Example 7

[0090] This embodiment is basically the same as the first embodiment, except that:

[0091] In the conductive agent preparation method of this embodiment, step 1) 5g LiCl and 50g CaSO4 are added to 5L of 1% graphene dispersion, and then 1L of water is added and stirred evenly, and then 500mL of polyethylene glycol is added and stirred evenly.

[0092] Finally, 54.1 g of Li2O2 / CaO2@Graphene conductive agent was obtained, in which the total mass percentage of Li2O2 and CaO2 was 7.6%.

[0093] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0094] Example 8

[0095] This embodiment is basically the same as the first embodiment, except that:

[0096] In the conductive agent preparation method of this embodiment, the conductive carbon black (Super-P) in step 1) is changed to natural graphite.

[0097] Finally, 52.7 g of Li2O2 / CaO2@NG conductive agent was obtained, in which the total mass percentage of Li2O2 and CaO2 was 5.2%.

[0098] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0099] Comparative Example 1

[0100] The conductive agent of the present application was not used, and the conductive carbon black (Super-P) in Example 1 was directly used as the conductive agent. The slurry preparation, coating, roller pressing process and battery preparation were the same as in Example 1.

[0101] Comparative Example 2

[0102] This embodiment is basically the same as the first embodiment, except that:

[0103] In the conductive agent preparation method of this embodiment, step 1) 30g of FeCl3 is added to 6L of water to fully dissolve, then 50g of conductive carbon black (Super-P) is added to the above solution and stirred evenly, and then 500mL of polyethylene glycol is added and stirred evenly.

[0104] Finally, 58.1 g of Fe2O3@SP conductive agent was obtained, in which the mass percentage of Fe2O3 was 13.9%.

[0105] The rest of the preparation steps, slurry preparation, coating, roller pressing process and battery preparation remain unchanged.

[0106] Table 1 Summary of key information of Examples and Comparative Examples

[0107]

[0108]

[0109] 1) Characterization of conductive agent morphology

[0110] Scanning electron microscope (SEM) testing

[0111] like Figure 1 The scanning electron microscope image of the conductive agent used in Example 1 is shown in FIG. Figure 1It can be seen that both the porous carbon-based nanomaterials and the metal peroxide nanoparticles have nanometer sizes.

[0112] 2) Characterization of the changes in Li2O content in the SEI film after battery formation and high-temperature cycling

[0113] The batteries after Example 1, Example 2, and Comparative Example 1 were disassembled to obtain negative electrode sheets. Then, a 2cm×2cm size negative electrode sheet was taken for XPS testing, and the O1s narrow spectrum was precisely scanned. The Li2O content was calculated as follows: the O1s spectrum was peaked, and the peak at ~528.9eV was the Li2O peak. The ratio of this peak area to the entire O1s peak area was calculated. The Li2O content on the surface of the negative electrode sodium hydroxide after formation can be obtained by multiplying the ratio of the Li2O peak by the ratio of the O element tested by XPS. The test results of the Li2O content after battery formation are as follows: Figure 2 .

[0114] The batteries formed in Example 1, Example 2, and Comparative Example 1 were charged to 3.8V at 1C at 45°C and then discharged to 2V at 1C for 900 cycles to obtain batteries after high-temperature cycling. The batteries after high-temperature cycling were disassembled to obtain negative electrode sheets, and then a negative electrode sheet of 2cm×2cm in size was taken for XPS testing, and the O1s narrow spectrum was precisely scanned. The Li2O content was calculated as follows: the O1s spectrum was peaked, and the peak at ~528.9eV was the Li2O peak. The ratio of this peak area to the entire O1s peak area was calculated. The Li2O content on the surface of the negative electrode sodium monoxide after high-temperature cycling can be obtained by multiplying the ratio of the Li2O peak by the ratio of the O element tested by XPS. The test results of the Li2O content after high-temperature cycling are as follows. Figure 2 .

[0115] Depend on Figure 2 It can be seen that the use of the conductive agent of the present application can significantly increase the Li2O content of the SEI film. At the same time, the conductive agent of the present application can maintain the Li2O content in the SEI film at a relatively high level during the battery cycle.

[0116] 3) Battery charge and discharge DC impedance test

[0117] The formed batteries of Examples 1-8, Comparative Examples 1, and 2 were charged to 3.8V at 1C and then discharged to 2V at 1C for 900 cycles at 45°C to obtain high-temperature cycled batteries. The formed and high-temperature cycled batteries were then subjected to the following charging and discharging DC impedance tests at room temperature.

[0118] The discharge DC impedance test steps at room temperature are as follows:

[0119] (1) Adjust the ambient temperature to 25°C, adjust the battery to 25% SOC, let it rest for 30 minutes, and then test the OCV.

[0120] (2) Charge with a 3C current for 30s and record the voltage data at 0s / 0.5s / 15s / 30s respectively.

[0121] (3) DC impedance (DCIR) uses the formula DCIR=(U0-U t ) / I calculation, record the voltage data at different times.

[0122] The discharge DC impedance test steps at room temperature are as follows:

[0123] (1) Adjust the ambient temperature to 25°C and adjust the battery to 80% SOC.

[0124] (2) Discharge with a current of 3C for 30s, and record the voltage data at 0s / 0.5s / 15s / 30s respectively.

[0125] (3) DC impedance (DCIR) uses the formula DCIR=(U0-U t ) / I calculation, record the voltage data at different times.

[0126] U0 is the voltage at 0s, U t is the voltage at the corresponding time;

[0127] SOC: State of Charge, refers to the percentage of the battery's current capacity to the total capacity;

[0128] OCV: Open Circuit Voltage, refers to the terminal voltage of the battery in the open circuit state;

[0129] DCIR: DC impedance resistor, refers to the battery impedance during DC charging / discharging.

[0130] The charge and discharge DC impedance tests of the batteries after formation and the batteries after high-temperature cycling in all embodiments and comparative examples are shown in Tables 2 and 3.

[0131] Table 2 Charge and discharge DC impedance test of the battery after formation

[0132]

[0133]

[0134] As can be seen from Table 2, the impedances of Examples 1-8 are significantly lower than those of Comparative Examples 1 and 2, indicating that the conductive agent of the present application has the effect of reducing battery impedance. This shows that the conductive agent containing metal peroxide nanoparticles can reduce battery impedance. At the same time, alkali metal and alkaline earth metal ions are less likely to deposit on the negative electrode and produce dendrites, which further helps to reduce the battery impedance. Among them, the impedances of Examples 2 and 4 are lower than those of Examples 5 and 6. From this, it can be seen that when the type of metal peroxide nanoparticles is the same, the content of metal peroxide nanoparticles in the range of 9%-22% can react with trace water inside the battery to generate O2. During the SEI film formation process, O2 can accelerate the generation rate of Li2O, ultimately increasing the content of the Li2O component without reducing the conductive properties of the conductive agent. It has a good effect of reducing impedance, thereby improving the battery rate performance. The results show that after using the conductive agent, the charge / discharge DC impedance of the battery after formation at room temperature is significantly reduced, which can improve the rate performance.

[0135] Table 3 Charge and discharge DC impedance test results of batteries after high temperature cycling

[0136]

[0137]

[0138] As can be seen from Table 3, the impedances of Examples 1-8 are significantly lower than those of Comparative Examples 1 and 2, indicating that the conductive agent of the present application has the effect of reducing battery impedance. This shows that the conductive agent containing metal peroxide nanoparticles can reduce battery impedance. At the same time, alkali metal and alkaline earth metal ions are less likely to deposit on the negative electrode and produce dendrites, which further helps reduce the battery impedance. The impedances of Examples 2 and 4 are lower than those of Examples 5 and 6. This shows that when the type of metal peroxide nanoparticles is the same, the content of metal peroxide nanoparticles in the range of 9%-22% can react with trace water inside the battery to generate O2. During the SEI film formation process, O2 can accelerate the generation rate of Li2O, ultimately increasing the content of the Li2O component without reducing the conductive properties of the conductive agent. It has a good impedance reduction effect, thereby improving the battery rate performance. The results show that after using the conductive agent, the charge / discharge DC impedance of the battery at room temperature after high-temperature cycling is significantly reduced, which can improve the rate performance.

[0139] 4) Battery capacity retention test

[0140] The batteries formed in Examples 1-8, Comparative Examples 1 and 2 were charged to 3.6V at 1C, then charged to 3.7V at 0.1C, then charged to 3.8V at 0.05C, then discharged to 2.2V at 1C, then discharged to 2.1V at 0.1C, and then discharged to 2V at 0.05C. The first cycle discharge capacity was recorded. After charging to 3.8V at 1C and discharging to 2V at 1C, 900 cycles were repeated. The batteries were charged to 3.6V at 1C, then charged to 3.7V at 0.1C, then charged to 3.8V at 0.05C, then discharged to 2.2V at 1C, then discharged to 2.1V at 0.1C, and then discharged to 2V at 0.05C. The discharge capacity was tested and the capacity retention rate was calculated. The test results of all Examples and Comparative Examples are shown in Table 4.

[0141] Table 4 Capacity retention of batteries after high temperature cycling

[0142]

[0143]

[0144] As can be seen from Table 4, the battery capacity retention rates of Examples 1-8 are significantly higher than those of Comparative Examples 1 and 2, indicating that the conductive agent of the present application has the effect of improving the battery capacity retention rate. It further illustrates that the conductive agent containing metal peroxide nanoparticles can improve the battery capacity retention rate. This is because alkali metal and alkaline earth metal ions are difficult to deposit on the negative electrode and produce dendrites, avoiding battery degradation and safety risks, and more conducive to improving the battery capacity retention rate, thereby improving battery life. Among them, the impedance of Examples 2 and 4 is lower than that of Examples 5 and 6. From this, it can be seen that when the type of metal peroxide nanoparticles is the same, the metal peroxide nanoparticle content is in the range of 9%-22%. The metal peroxide nanoparticles can better control the oxygen release rate. During the SEI film formation process, O2 can accelerate the generation rate of Li2O, ensuring that the SEI film is continuously replenished with Li2O. At the same time, it can better maintain the conductive properties of the conductive agent, which has the effect of improving the battery capacity retention rate, thereby improving the battery life. The results show that after using the conductive agent, the battery capacity retention rate after high-temperature cycling is significantly increased, which helps to improve the battery life.

[0145] In summary, maintaining a high level of Li2O content in the battery SEI film can significantly improve the battery's rate performance and cycle life.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A conductive agent, characterized in that The invention comprises porous carbon-based nanomaterials and metal peroxide nanoparticles in their pores.

2. The conductive agent according to claim 1, characterized in that The metal peroxide nanoparticles include at least one of alkali metal peroxide nanoparticles and alkaline earth metal peroxide nanoparticles.

3. The conductive agent according to claim 1, characterized in that The average pore diameter of the porous carbon-based nanomaterial is 50nm-100nm.

4. The conductive agent according to any one of claims 1 to 3, characterized in that: The porous carbon-based nanomaterial includes at least one of acetylene black, conductive carbon black, carbon nanotubes and graphene.

5. The conductive agent according to any one of claims 2 to 4, characterized in that: The alkali metal peroxide nanoparticles include at least one of Li2O2, Na2O2, K2O2, Rb2O2, and Cs2O2.

6. The conductive agent according to any one of claims 2 to 4, characterized in that: The alkaline earth metal peroxide nanoparticles include at least one of BeO2, MgO2, CaO2, SrO2, and BaO2.

7. The conductive agent according to any one of claims 2 to 6, characterized in that: Based on the total mass of the conductive agent, the content of the metal peroxide nanoparticles is 1% to 45%.

8. A method for preparing a conductive agent as claimed in claim 1, characterized in that: The preparation method comprises the following steps: S1: mixing porous carbon-based nanomaterials, metal salts, surfactants, and solvents; S2 adjusts the pH to 7-8 and stirs to obtain a suspension; S3: adding an H2O2 aqueous solution to the suspension obtained in step S2, and then adjusting the pH value to 9-10, and reacting to obtain the conductive agent.

9. The method for preparing the conductive agent according to claim 8, characterized in that: In S1, the metal in the metal salt includes at least one of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba.

10. The method for preparing the conductive agent according to claim 8 or 9, characterized in that: In the S1, the acid radical in the metal salt includes Cl - , NO 3- , SO4 2- , SO2(CF3)2 2- At least one of .

11. The method for preparing a conductive agent according to claim 8, characterized in that: In S1, the mass ratio of the porous carbon-based nanomaterial to the metal salt is 1:0.5 to 1:2.

5.

12. The method for preparing a conductive agent according to claim 8, characterized in that: In S1, the surfactant includes at least one of polyethylene glycol, polyvinyl pyrrolidone, polyvinyl alcohol, dextran, and diethylene glycol dimethyl ether.

13. A pole piece, characterized in that: The conductive agent comprises the conductive agent according to any one of claims 1 to 7 or the conductive agent prepared by the preparation method according to any one of claims 8 to 12.

14. A battery, characterized in that: The invention comprises the pole piece described in claim 13.

15. A battery pack, characterized in that: Comprising at least two batteries as claimed in claim 14.

16. An electrical device, characterized in that: The invention comprises the battery according to claim 14 or the battery pack according to claim 15.

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