Current collector for pre-lithiation of positive electrode and preparation method therefor, positive electrode sheet, lithium-ion battery and electric device

Abstract

A current collector for the pre-lithiation of a positive electrode and a preparation method therefor, a positive electrode sheet, a lithium-ion battery and an electric device. The current collector for the pre-lithiation of a positive electrode comprises a porous current collector, wherein an oxygen capturing agent and a pre-lithiation agent are contained in the pores of the porous current collector.

Description

Positive electrode lithium supplementing current collector, preparation method thereof, positive electrode sheet, lithium ion battery and electric device

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to Chinese Patent Application No. CN202411062256.5, filed on August 5, 2024, the contents of which are incorporated herein in their entirety. TECHNICAL FIELD

[0003] The present disclosure relates to a positive electrode lithium supplementing current collector, a preparation method thereof, a positive electrode sheet, a lithium ion battery and an electric device. BACKGROUND

[0004] In the charging and discharging process of a lithium ion battery, the solvent of the electrolyte is easily reduced on the surface of the negative electrode to form a solid-state electrolyte passivation film (SEI), which avoids further reaction and consumption of active lithium, and this process is called film formation process, which is crucial to the performance and stability of the lithium ion battery. In the film formation process, due to a series of complex chemical reactions and physical processes, the active lithium in the positive electrode material may be lost, which in turn affects the performance and cycle life of the battery. In order to make up for the loss of active lithium in the film formation process and improve the utilization efficiency of active lithium in the positive electrode material, researchers have proposed lithium supplementing technology. Compared with negative electrode lithium supplementing technology such as lithium powder or lithium ribbon, positive electrode lithium supplementing process has the advantages of simple equipment, relatively mild generation environment, small danger and good battery consistency, but at the same time has many defects: 1) the residual alkali of the positive electrode lithium supplementing agent is high, which easily leads to chemical gel during the batching process, affecting the processing performance of the electrode sheet; 2) the decomposition residues of the positive electrode lithium supplementing agent occupy a certain electrode sheet space, reducing the porosity of the electrode sheet and affecting the lithium ion diffusion on the surface of the positive electrode active particles, resulting in reduced battery power performance; 3) the positive electrode lithium supplementing agent reduces the proportion of active materials in the electrode sheet, reducing the battery capacity; 4) the release products of the positive electrode lithium supplementing agent cause side reactions of the electrolyte, leading to problems such as battery cell swelling and valve opening hazards.

[0005] In order to solve the above problems, the existing positive electrode lithium supplementing process has been improved, for example, a coating containing a lithium supplementing agent is added to the current collector before preparing the positive electrode active material layer; or the lithium supplementing agent slurry is directly mixed with the positive electrode slurry to prepare a positive electrode sheet. These methods can to some extent solve the problem of the influence of the residual alkali of the positive electrode lithium supplementing agent on the preparation of the positive electrode sheet, but the introduction of the lithium supplementing agent coating increases the thickness of the non-active current collector, reduces the volume energy density of the battery, and increases the transmission path of the active material and the current collector, making the electronic transmission resistance larger and the power performance lower. The method of directly mixing the lithium supplementing agent with the positive electrode slurry has the problem of uneven mixing, which easily causes the aggregation of the lithium supplementing agent, and cannot completely avoid the influence of the residual alkali of the lithium supplementing agent on the stability of the positive electrode slurry

[0006] Therefore, there is still a need for an improved solution that helps to improve the electrical performance of the battery while ensuring the safety of the battery. SUMMARY

[0007] The purpose of the present disclosure is to provide a positive electrode lithium supplement current collector and a preparation method thereof, a positive electrode tab, a lithium ion battery and an electrical equipment, so as to improve the electrical performance and safety performance of the lithium ion battery.

[0008] To achieve the above-mentioned purpose, the first aspect of the present disclosure provides a positive electrode lithium supplement current collector, comprising a porous current collector, wherein the pores of the porous current collector contain an oxygen capturing agent and a lithium supplement agent.

[0009] Optionally, the oxygen capturing agent comprises an aromatic compound and / or a thioamino compound.

[0010] Optionally, the oxygen capturing agent comprises at least one of 2,2'-diphenylbutanedione, methyl cinnamate, dithio amino methane, diphenyl ketone and diphenyl anthracene.

[0011] Optionally, the lithium supplement agent comprises at least one of lithium ferrite, lithium oxalate, lithium nickelate and lithium carbonate.

[0012] Optionally, the porosity of the porous current collector is 20-70%.

[0013] Optionally, the porous current collector has first pores with a pore size of 50-100 nm and second pores with a pore size of 10-100 μm, the pore volume of the first pores accounts for 10-30% of the total pore volume, and the pore volume of the second pores accounts for 70-90% of the total pore volume.

[0014] Optionally, the oxygen capturing agent is contained in the first pores, and the lithium supplement agent is contained in the second pores.

[0015] Optionally, based on 100 parts by weight of the positive electrode lithium supplement current collector, the content of the oxygen capturing agent is 0.1-5 parts by weight, and the content of the lithium supplement agent is 1-50 parts by weight.

[0016] Optionally, the pores of the porous current collector further contain a binder and a conductive agent, and the weight ratio of the lithium supplement agent, the binder and the conductive agent is 100:(1-20):(0.5-20).

[0017] Optionally, the conductive agent comprises at least one of carbon black, carbon tube and graphene.

[0018] The second aspect of the present disclosure provides a method for preparing the positive electrode lithium supplement current collector of the first aspect of the present disclosure, which comprises:

[0019] obtaining a porous current collector, and preparing a mixed slurry containing an oxygen capturing agent, a lithium supplement agent and a solvent;

[0020] loading the mixed slurry into the pores of the porous current collector, and then removing the solvent to obtain the positive electrode lithium supplementing current collector.

[0021] Optionally, the content of the solvent is 40-80 parts by weight based on 100 parts by weight of the lithium supplementing slurry.

[0022] Optionally, the method of loading the mixed slurry into the pores of the porous current collector is vacuum impregnation, and the conditions of the vacuum impregnation include a vacuum degree of 5-50 Pa, a temperature of 20-50℃, and an impregnation time of 5-15 h.

[0023] Optionally, the porous current collector has first pores with a pore size of 50-100 nm and second pores with a pore size of 10-100 μm, the pore volume of the first pores accounts for 10-30% of the total pore volume, and the pore volume of the second pores accounts for 70-90% of the total pore volume; the method comprises:

[0024] subjecting the foil-shaped current collector to first etching treatment to obtain a current collector containing the first pores; wherein the conditions of the first etching treatment include an ion beam current of 10-30 pA, a residence time of 100-300 μs, and laser drilling at a laser frequency of 100-200 Hz and a drilling speed of 1-2 m / min;

[0025] preparing a first slurry containing the oxygen capturing agent, loading the first slurry into the first pores of the current collector containing the first pores through first vacuum impregnation to obtain a current collector after first vacuum impregnation; wherein the conditions of the first vacuum impregnation include a vacuum degree of 5-50 Pa, a temperature of 20-50℃, and an impregnation time of 5-15 h;

[0026] subjecting the current collector after first vacuum impregnation to second etching treatment to obtain a current collector containing the second pores; wherein the conditions of the second etching treatment include an ion beam current of 10-30 pA, a residence time of 300-500 μs, and laser drilling at a laser frequency of 100-200 Hz and a drilling speed of 0.5-1.5 m / min;

[0027] preparing a second slurry containing the lithium supplementing agent and the solvent, loading the second slurry into the second pores of the current collector containing the second pores through second vacuum impregnation, and then removing the solvent to obtain the positive electrode lithium supplementing current collector; wherein the conditions of the second vacuum impregnation include a vacuum degree of 5-50 Pa, a temperature of 20-50℃, and an impregnation time of 5-15 h.

[0028] In a third aspect, the present disclosure provides a positive electrode tab, comprising the positive electrode lithium supplementing current collector according to the first aspect of the present disclosure and a positive electrode active material layer arranged on the surface of the positive electrode lithium supplementing current collector.

[0029] In a fourth aspect, the present disclosure provides a lithium ion battery, comprising the positive electrode tab according to the third aspect of the present disclosure.

[0030] In a fifth aspect, the present disclosure provides a power utilization device, comprising the lithium ion battery according to the fourth aspect of the present disclosure.

[0031] According to the above technical solution, the present disclosure integrates the lithium supplementing agent and the oxygen capturing agent into the porous current collector, reduces or avoids the direct contact between the lithium supplementing agent and the positive electrode active material, thereby reducing the influence of the lithium supplementing agent residual alkali substance on the stability of the positive electrode material and improving the processing performance of the tab; at the same time, the lithium supplementing agent and its decomposition residues can be retained in the pores of the porous current collector, reducing the negative influence on the power performance and capacity of the battery, and effectively improving the electrical performance; in addition, the oxygen capturing agent can avoid the electrolyte side reaction caused by the release product of the lithium supplementing agent, thereby reducing the risk of gas generation, reducing the gas swelling and valve opening phenomenon of the battery cell, and significantly improving the safety performance of the battery.

[0032] Other features and advantages of the present disclosure will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and are used together with the following specific embodiments to explain the present disclosure, but do not constitute a limitation of the present disclosure. In the drawings:

[0034] FIG. 1 is a structural schematic diagram of one specific embodiment of the positive electrode tab provided by the present disclosure.

[0035] LEGEND OF THE FIGURES

[0036] 1 - positive electrode lithium supplementing current collector, 2 - positive electrode active material layer. DETAILED DESCRIPTION

[0037] The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0038] In a first aspect, the present disclosure provides a positive electrode lithium supplementing current collector, comprising a porous current collector, wherein the pores of the porous current collector contain an oxygen capturing agent and a lithium supplementing agent.

[0039] According to the present disclosure, since the porous current collector has a porous structure, the oxygen capturing agent and the lithium supplementing agent are encapsulated in the pores of the porous current collector, which can reduce or avoid the direct contact between the lithium supplementing agent and the positive active material, thereby reducing the influence of the lithium supplementing agent on the stability of the positive active material and improving the processing performance of the electrode sheet. At the same time, the lithium supplementing agent and its decomposition residues can be retained in the pores of the porous current collector and will not reduce the porosity of the active material area due to occupying the electrode sheet space, thereby reducing the negative influence on the battery power performance and capacity and effectively improving the electrical performance. In particular, the oxygen capturing agent can be used to capture and neutralize singlet oxygen molecules released by the decomposition of the lithium supplementing agent, so as to inhibit the occurrence of side reactions such as electrolyte decomposition and oxidation caused by the singlet oxygen, thereby reducing the risk of gas production, reducing the gas swelling and valve opening phenomenon of the battery, and significantly improving the safety performance of the battery.

[0040] The oxygen capturing agent is an organic compound capable of specifically reacting with singlet oxygen. In the present disclosure, the oxygen capturing agent can include aromatic compounds and / or thioamino compounds, wherein the aromatic compounds can include at least one of aromatic ketones, aromatic esters, aromatic alcohols, aromatic hydrocarbons, aromatic aldehydes, aromatic phenols, and halogenated aromatic hydrocarbons. For example, the aromatic ketones can include 2,2'-diphenylbutanedione, diphenylacetone, etc.; the aromatic hydrocarbons can include diphenylanthracene, etc.; the aromatic esters can include methyl cinnamate, ethyl benzoate, ethyl cinnamate, etc.; the aromatic aldehydes can include vanillin, etc.; the thioamino compounds can include dithioamino methane, etc.; the aromatic phenols can include catechol, phenol, etc.; the aromatic alcohols can include benzyl alcohol, etc.; and the halogenated aromatic hydrocarbons can include bromobenzene, benzene tetrachloride, etc.

[0041] In a preferred embodiment, the oxygen capturing agent includes at least one of 2,2'-diphenylbutanedione (English name: 1,4-Diphenyl-2,3-butanedione), methyl cinnamate, dithioamino methane (English name: Methanesulfinamide), diphenylacetone, and diphenylanthracene. Using the above-mentioned organic compounds as the oxygen capturing agent can facilitate the efficient capture of singlet oxygen molecules, effectively inhibit the electrolyte side reactions, significantly reduce the risk of gas production, and improve the safety performance of the battery.

[0042] According to the present disclosure, the lithium supplementing agent is a lithium-containing compound, specifically, the lithium supplementing agent can include at least one of lithium ferrite, lithium oxalate, lithium nickelate, and lithium carbonate, and preferably at least one selected from lithium ferrite and lithium nickelate. The lithium supplementing agent can have a particle shape and can have a particle size matching the pore size of the pores of the porous current collector. For example, the particle size of the lithium supplementing agent can be 1 μm to 100 μm.

[0043] According to the present disclosure, the porous current collector has a porous structure, and in order to have a better lithium supplement effect, the porosity of the porous current collector can be 20-70%, preferably 30-50%. The porosity refers to the percentage of the pore volume in the porous current collector to the total volume (i.e. the apparent volume) of the porous current collector in a natural state.

[0044] The pores in the porous current collector are uniformly distributed and can be through holes or blind holes; preferably, the pores in the porous current collector are through holes (i.e. holes that penetrate the current collector) to improve the lithium supplement effect. The pores in the porous current collector can have a certain pore size range, so as to accommodate a certain amount of lithium supplement agent and oxygen capturing agent. The specific pore size can be adjusted according to actual needs. For example, the pore size of the pores in the porous current collector can be 50 nm-100 μm.

[0045] In a preferred embodiment, the porous current collector can have first pores with a pore size of 50 nm-100 nm and second pores with a pore size of 10 μm-100 μm, the pore volume of the first pores accounts for 10-30% of the total pore volume, and the pore volume of the second pores accounts for 70-90% of the total pore volume. Further, the oxygen capturing agent can be accommodated in the first pores, and the lithium supplement agent can be accommodated in the second pores, at this time, the lithium supplement agent has a particle size that matches the pore size of the second pores. By arranging the oxygen capturing agent in smaller pores and the lithium supplement agent in larger pores, the lithium supplement effect can be further optimized and the risk of gas production can be reduced, so that the battery has significantly improved electrical performance and safety performance.

[0046] The material of the porous current collector can be common in the art, such as aluminum foil. The thickness of the porous current collector can be adjusted within a certain range. Specifically, the thickness of the porous current collector can be 10 μm-70 μm.

[0047] According to the present disclosure, the amount of the oxygen capturing agent and the lithium supplement agent can be adjusted within a certain range. In a specific embodiment, based on 100 parts by weight of the positive electrode lithium supplement current collector, the content of the oxygen capturing agent can be 0.1-5 parts by weight, preferably 0.5-2 parts by weight; and the content of the lithium supplement agent can be 1-50 parts by weight, preferably 5-20 parts by weight. By controlling the amount of the oxygen capturing agent and the lithium supplement agent, favorable electrical performance and safety performance of the battery can be achieved.

[0048] Further, the pores of the porous current collector also contain a binder and a conductive agent, at this time, the pores of the porous current collector also contain a binder and a conductive agent, the weight ratio of the lithium supplement agent, the binder and the conductive agent can be 100:(1-20):(0.5-20); under the above content ratio, it is beneficial to reduce the sheet resistance and improve the electrical performance of the battery. The types of the binder and the conductive agent can be common in the art, specifically, the binder can be polyvinylidene fluoride (PVDF); the conductive agent can include at least one of carbon black, carbon nanotubes, and graphene.

[0049] In a second aspect of the present disclosure, a method for preparing the positive electrode lithium supplement current collector of the first aspect of the present disclosure is provided, which comprises the following steps S1-S2:

[0050] S1, obtaining a porous current collector, preparing a mixed slurry containing an oxygen capturing agent, a lithium supplement agent and a solvent;

[0051] S2, loading the mixed slurry into the pores of the porous current collector, and then removing the solvent to obtain a positive electrode lithium supplement current collector.

[0052] In step S1, the porous current collector can be a commercially available product with the characteristics described above, or can be prepared by existing technology. In one embodiment, the method for preparing the porous current collector comprises: etching a foil-shaped current collector to obtain the porous current collector. The etching conditions can include: the ion beam current of focused ion beam etching is 1-50 pA, the residence time is 50-1000 s, the laser frequency of laser drilling is 100-500 Hz, and the drilling speed is 0.5-5 m / min.

[0053] The mixed slurry can also contain a binder and a conductive agent, and the content of each component satisfies the range described above. The specific types of the oxygen capturing agent, the lithium supplement agent, the binder and the conductive agent are as described above. The solvent can be N-methyl pyrrolidone (NMP), and the content of the solvent can be 40-80 parts by weight based on 100 parts by weight of the mixed slurry. The mixed slurry can be obtained by mixing the above components.

[0054] In step S2, the method for loading the mixed slurry into the pores of the porous current collector can be vacuum impregnation, and the conditions of the vacuum impregnation can include: the vacuum degree is 5-50 Pa, the temperature is 20-50℃, and the impregnation time is 5-15 h. The method for removing the solvent is well known to those skilled in the art, for example, the porous current collector can be dried to remove the solvent, and the drying conditions can be conventional in the art, for example: the temperature is 50℃-100℃, and the time is 5 min-10 min.

[0055] In the preferred embodiment of the porous current collector having the first pores with a pore size of 50 nm to 100 nm and the second pores with a pore size of 10 μm to 100 μm, the oxygen capturing agent is contained in the first pores and the lithium supplementing agent is contained in the second pores, the method for preparing the positive electrode lithium supplementing current collector comprises the following steps:

[0056] The foil-shaped current collector is subjected to a first etching treatment to obtain a current collector containing first pores; wherein the conditions of the first etching treatment can include: an ion beam current of 10 to 30 pA, a residence time of 100 to 300 μs, and laser drilling with a laser frequency of 100 to 200 Hz and a drilling speed of 1 to 2 m / min;

[0057] A first slurry containing an oxygen capturing agent is prepared, and the first slurry is loaded into the first pores of the current collector containing the first pores by a first vacuum impregnation to obtain a current collector after the first vacuum impregnation; wherein the conditions of the first vacuum impregnation can include: a vacuum degree of 5 to 50 Pa, a temperature of 20 to 50 °C, and an impregnation time of 5 to 15 h;

[0058] The current collector after the first vacuum impregnation is subjected to a second etching treatment to obtain a current collector containing second pores; wherein the conditions of the second etching treatment can include: an ion beam current of 10 to 30 pA, a residence time of 300 to 500 μs, and laser drilling with a laser frequency of 100 to 200 Hz and a drilling speed of 0.5 to 1.5 m / min;

[0059] A second slurry containing a lithium supplementing agent and a solvent is prepared, and the second slurry is loaded into the second pores of the current collector containing the second pores by a second vacuum impregnation, and then the solvent is removed to obtain a positive electrode lithium supplementing current collector; wherein the conditions of the second vacuum impregnation can include: a vacuum degree of 5 to 50 Pa, a temperature of 20 to 50 °C, and an impregnation time of 5 to 15 h. The second slurry can also contain the above-mentioned binder and conductive agent.

[0060] In a third aspect of the present disclosure, a positive electrode tab is provided, which, as shown in FIG. 1, comprises the positive electrode lithium supplementing current collector 1 of the first aspect of the present disclosure and a positive electrode active material layer 2 arranged on the surface of the positive electrode lithium supplementing current collector 1.

[0061] The positive electrode active material layer 2 is formed of a positive electrode active material, which can be lithium iron phosphate, lithium manganese iron phosphate, etc. The amount of the positive electrode active material can be adjusted within a certain range, for example, the weight ratio of the positive electrode active material to the lithium supplementing agent can be (100-105): 1. The surface density of the positive electrode active material can be 360-500 g / m 2 , and the compacted density can be 2-2.6 g / m 3 .

[0062] The preparation method of the positive electrode tab is not particularly limited in the present disclosure, and the positive electrode active material can be coated on the surface of the positive electrode lithium supplement current collector 1 by using the processes and equipment well known in the art, and the positive electrode tab is obtained by drying.

[0063] The positive electrode tab of the present disclosure not only has excellent lithium supplement effect, which is beneficial to slow down the loss of active lithium in the positive electrode material, but also can effectively inhibit the electrolyte side reaction and reduce the risk of gas production. In addition, it also has good processability and is suitable for large-scale industrial production. The use of the positive electrode tab in lithium ion batteries is beneficial to improve the capacity and power performance of the battery, avoid the hidden dangers of cell swelling and valve opening, and significantly improve the safety performance and stability of the battery.

[0064] In a fourth aspect, the present disclosure provides a lithium ion battery comprising the positive electrode tab of the third aspect of the present disclosure. The specific structure of the lithium ion battery is not particularly limited in the present disclosure, and it can include other structures commonly used in the art, such as negative electrodes, separators, and electrolytes, etc. The specific types of substances can be well known to those skilled in the art, and the present disclosure will not be repeated here.

[0065] In a fifth aspect, the present disclosure provides an electrical equipment comprising the lithium ion battery of the fourth aspect of the present disclosure.

[0066] The present disclosure is further illustrated by the following examples, but is not used to limit the present disclosure.

[0067] The raw materials and reagents used in the examples and comparative examples are commercially available products.

[0068] The test method for the porosity of the current collector is the mercury intrusion porosimetry test method, and the test method for the pore distribution is the BET pore size distribution test method.

[0069] Example 1

[0070] The lithium supplement agent (lithium ferrite), oxygen capture agent (methyl cinnamate), binder (PVDF), conductive agent (carbon black), and solvent (N-methyl pyrrolidone) were mixed in a weight ratio of 10:1:0.2:0.1:10 to obtain a mixed slurry.

[0071] A 20-μm-thick aluminum foil current collector was etched under the following conditions: focused ion beam current, 10 pA; residence time, 200 μs; laser frequency, 200 Hz; and punching speed, 1 m / min, to obtain a porous aluminum foil current collector having a porosity of 50%. The above mixed slurry was loaded into the pores of the aluminum foil porous current collector by vacuum impregnation (conditions: vacuum degree, 5 Pa; temperature, 20°C; and time, 5 h), and the positive electrode lithium supplement current collector was obtained after drying. The content of the oxygen capturing agent was 0.5 parts by weight and the content of the lithium supplement agent was 5 parts by weight, based on 100 parts by weight of the positive electrode lithium supplement current collector.

[0072] A lithium iron phosphate slurry (areal density, 400 g / m 2 ; and tap density, 2.6 g / m 3 ) was coated on the surface of the above positive electrode lithium supplement current collector (weight ratio of lithium iron phosphate slurry to lithium supplement agent, 100:1), and the active material slurry was observed to have good flowability during the coating process. Then, the positive electrode sheet was obtained after drying.

[0073] Example 2

[0074] The positive electrode sheet was prepared according to the method of Example 1, except that the above mixed slurry was loaded into the pores of the aluminum foil porous current collector by vacuum impregnation (conditions: vacuum degree, 5 Pa; temperature, 20°C; and time, 10 h), and the positive electrode lithium supplement current collector was obtained after drying. The same lithium supplement slurry as in Example 1 was loaded into the pores of the aluminum foil porous current collector by vacuum impregnation under the same conditions, and the content of the oxygen capturing agent was 1 part by weight and the content of the lithium supplement agent was 10 parts by weight, based on 100 parts by weight of the positive electrode lithium supplement current collector.

[0075] Example 3

[0076] The positive electrode sheet was prepared according to the method of Example 1, except that the above mixed slurry was loaded into the pores of the aluminum foil porous current collector by vacuum impregnation (conditions: vacuum degree, 5 Pa; temperature, 40°C; and time, 15 h), and the positive electrode lithium supplement current collector was obtained after drying. The same lithium supplement slurry as in Example 1 was loaded into the pores of the aluminum foil porous current collector by vacuum impregnation under the same conditions, and the content of the oxygen capturing agent was 2 parts by weight and the content of the lithium supplement agent was 20 parts by weight, based on 100 parts by weight of the positive electrode lithium supplement current collector.

[0077] Example 4

[0078] The oxygen capturing agent (methyl cinnamate) was used as a first slurry, and the lithium supplement agent (lithium ferrite), binder (PVDF), conductive agent (carbon black), and solvent (N-methyl pyrrolidone) were mixed to obtain a second slurry, and the weight ratio of the lithium supplement agent, binder, conductive agent, and solvent was 20:1.5:0.2:0.1:20.

[0079] The foil-shaped current collector with a thickness of 40 μm was subjected to a first etching treatment under the conditions of a current of 20 pA, a residence time of 200 μs, a laser frequency of 200 Hz, and a punching speed of 2 m / min, to obtain a current collector containing first pores with a pore diameter of 50 nm to 100 nm, which accounted for 30% of the total pore volume; the first slurry was loaded into the first pores of the current collector by first vacuum impregnation under the conditions of a vacuum degree of 30 Pa, a temperature of 20°C, and a time of 5 h; the obtained current collector was subjected to a second etching treatment under the conditions of a current of 30 pA, a residence time of 300 μs, a laser frequency of 200 Hz, and a punching speed of 1 m / min, to obtain a current collector containing second pores with a pore diameter of 10 μm to 100 μm, which accounted for 70% of the total pore volume; the second slurry was loaded into the second pores of the current collector by second vacuum impregnation under the conditions of a vacuum degree of 50 Pa, a temperature of 20°C, and a time of 10 h, and then the solvent was removed, to obtain a positive electrode lithium supplementing current collector. The porosity of the positive electrode lithium supplementing current collector was 50%, and, based on 100 parts by weight of the positive electrode lithium supplementing current collector, the oxygen trapping agent was contained in the first pores in an amount of 1.5 parts by weight, and the lithium supplementing agent was contained in the second pores in an amount of 20 parts by weight.

[0080] The lithium iron phosphate slurry was coated on the surface of the positive electrode lithium supplementing current collector according to the method of Example 1, and it was observed that the active material slurry had good fluidity during the coating process. Then, the positive electrode tab was obtained by drying.

[0081] Example 5

[0082] The positive electrode tab was prepared according to the method of Example 1, except that the porosity of the porous current collector was 70%, and the weight ratio of the lithium supplementing agent, the oxygen trapping agent, the binder, the conductive agent, and the solvent was 40:3:2:1:40. Based on 100 parts by weight of the positive electrode lithium supplementing current collector, the content of the oxygen trapping agent was 3 parts by weight, and the content of the lithium supplementing agent was 40 parts by weight.

[0083] Example 6

[0084] The positive electrode tab was prepared according to the method of Example 1, except that the oxygen trapping agent ethyl benzoate was used to replace the methyl cinnamate in Example 1.

[0085] Comparative Example 1

[0086] The lithium iron phosphate slurry and the lithium supplementing agent (lithium ferrite) were mixed in a weight ratio of 100:1, and the obtained mixed slurry was coated on the surface of an aluminum foil current collector. It was observed that the active material slurry had a serious gelation phenomenon and could not maintain good fluidity during the coating process. Then, the positive electrode tab was obtained by drying.

[0087] Comparative Example 2

[0088] The positive electrode sheet was prepared according to the method of Example 1, except that the mixed slurry did not contain an oxygen capturing agent.

[0089] Test Example

[0090] The positive electrode sheets of the examples and comparative examples were subjected to capacity test, high temperature cycle test, high temperature storage gas production test and low temperature power test, and the test methods were as follows, and the results are shown in Table 1.

[0091] Capacity test: The positive electrode sheets of the examples and comparative examples were respectively matched with graphite negative electrodes to prepare soft package batteries with a nominal capacity of about 2 Ah by the lamination method. At room temperature 25±3℃, 1 / 3C constant current charging to 3.8V, standing for 5min, 0.1C charging to 3.8V, standing for 30min; discharge: at room temperature 25±3℃, 1 / 3C constant current discharge to 2.0V, standing for 30min. The above steps were cycled for three cycles, and the capacity of the last cycle was recorded as C0.

[0092] High temperature cycle test: at 60±3℃, after 7h of battery environment adaptation before the start of the cycle, the test was started, 0.5C constant current charging to 3.75V (current calculation according to RPTs capacity test results), standing for 30min; discharge, at 60±3℃, 0.5C constant current discharge to 2.0V (current calculation according to RPTs capacity test results), standing for 30min. Record the charge and discharge capacity / energy / voltage data. Take the discharge capacity C1 of the first cycle as the reference, and calculate the capacity retention rate at 200 cycles.

[0093] High temperature storage gas production test: at room temperature 25±3℃, 1 / 3C constant current charging to 3.8V, standing for 5min, 0.1C charging to 3.8V, standing for 30min; then 1 / 3C constant current discharge to 2.0V, standing for 30min; repeat three times to record the third discharge capacity as C0. Then 1 / 3C constant current charging to 3.8V, standing for 5min, 0.1C charging to 3.8V, standing for 30min to adjust the load to 100% SOC, and then store at 60℃ for 7D, and use the displacement device to test the gas production.

[0094] Low temperature power test: at-10℃, the battery was tested after 6h of environment adaptation. At-10℃, the battery was discharged to the cut-off voltage at 0.2C, and then stood for 30min; charged to 3.8V at 1 / 3C, stood for 5min, and then charged to 3.8V at 0.1C, stood for 30min; discharged to the cut-off voltage in turn at 0.2C / 1 / 3C / 1C / 1.5C / 2C / 3C, and then stood for 30min (if the current is greater than or equal to 1C, stand for 1h); record the capacity / energy / median voltage / temperature rise of the charge and discharge steps, and the discharge ratio = discharge capacity at this discharge current / discharge capacity at 0.2C discharge current.

[0095] Table 1

[0096] As can be seen from Table 1, the positive electrode plate prepared in the example has higher capacity, cycle capacity retention rate and low-temperature rate discharge ratio, and lower full-charge storage gas production rate, and exhibits excellent electrical performance and safety performance.

[0097] The preferred embodiments of the present disclosure are described in detail above with reference to the drawings, but the present disclosure is not limited to the specific details of the above-described embodiments, and various simple modifications can be made to the technical solutions of the present disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0098] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present disclosure will not further describe various possible combination manners.

[0099] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed by the present disclosure.

Claims

1. A positive electrode lithium supplementing current collector, characterized by, The porous current collector comprises pores containing an oxygen capturing agent and a lithium supplement agent.

2. The positive-lithium-supplementing current collector according to claim 1, wherein The oxygen capturing agent comprises an aromatic compound and / or a thioamino compound.

3. The positive-lithium-supplementing current collector according to claim 1 or 2, wherein The oxygen capturing agent comprises at least one of 2,2'-diphenylbutanedione, methyl cinnamate, dithioaminomethane, diphenylacetone and diphenylanthracene.

4. The positive-electrode lithium supplementing current collector according to any one of claims 1 to 3, wherein The lithium supplement agent comprises at least one of lithium ferrite, lithium oxalate, lithium nickelate and lithium carbonate.

5. The positive-electrode lithium supplementing current collector according to any one of claims 1 to 4, wherein The porosity of the porous current collector is 20-70%.

6. The positive-electrode lithium supplementing current collector according to any one of claims 1 to 5, wherein The porous current collector has first pores with a pore size of 50-100 nm and second pores with a pore size of 10-100 microns, the pore volume of the first pores accounts for 10-30% of the total pore volume, and the pore volume of the second pores accounts for 70-90% of the total pore volume.

7. The positive-lithium-supplementing current collector according to claim 6, wherein The oxygen capturing agent is contained in the first pores, and the lithium supplement agent is contained in the second pores.

8. The positive-electrode lithium supplementing current collector according to any one of claims 1 to 7, wherein The content of the oxygen capturing agent is 0.1-5 parts by weight based on 100 parts by weight of the positive electrode lithium supplement current collector, and the content of the lithium supplement agent is 1-50 parts by weight.

9. The positive-electrode lithium supplementing current collector according to any one of claims 1 to 8, wherein The pores of the porous current collector also contain a binder and a conductive agent, and the weight ratio of the lithium supplement agent, the binder and the conductive agent is 100:(1-20):(0.5-20).

10. The positive-lithium-supplementing current collector according to claim 9, wherein The conductive agent comprises at least one of carbon black, carbon tubes and graphene.

11. A method for producing the positive-electrode lithium supplementing current collector according to any one of claims 1 to 10, characterized by, The method comprises: obtaining a porous current collector, preparing a mixed slurry containing an oxygen capturing agent, a lithium supplement agent and a solvent; loading the mixed slurry into the pores of the porous current collector, and then removing the solvent to obtain a positive electrode lithium supplement current collector.

12. The method of claim 11, wherein, The content of the solvent is 40-80 parts by weight based on 100 parts by weight of the mixed slurry; and / or, the method for loading the mixed slurry into the pores of the porous current collector is a vacuum impregnation method, and the conditions of the vacuum impregnation method comprise a vacuum degree of 5-50 Pa, a temperature of 20-50°C and an impregnation time of 5-15 h.

13. The method of claim 11 or 12, wherein, The porous current collector has first pores with a pore size of 50-100 nm and second pores with a pore size of 10-100 microns, the pore volume of the first pores accounts for 10-30% of the total pore volume, and the pore volume of the second pores accounts for 70-90% of the total pore volume. The method for preparing the positive electrode lithium supplement current collector comprises: subjecting a foil-shaped current collector to a first etching treatment to obtain a current collector containing the first pores; wherein the conditions of the first etching treatment comprise an ion beam current of 10-30 pA, a residence time of 100-300 microseconds, and laser punching at a laser frequency of 100-200 Hz and a punching speed of 1-2 m / min; preparing a first slurry containing the oxygen capturing agent, and loading the first slurry into the first pores of the current collector containing the first pores through a first vacuum impregnation to obtain a current collector after the first vacuum impregnation; wherein the conditions of the first vacuum impregnation comprise a vacuum degree of 5-50 Pa, a temperature of 20-50°C and an impregnation time of 5-15 h; The first vacuum-impregnated current collector is subjected to a second etching treatment to obtain a current collector containing the second holes; wherein the second etching treatment conditions include: an ion beam current of 10-30 pA, a residence time of 300-500 μs, and laser drilling at a laser frequency of 100-200 Hz and a drilling speed of 0.5-1.5 m / min; A second slurry containing the lithium supplement agent and a solvent is prepared, the second slurry is loaded into the second holes of the current collector containing the second holes through a second vacuum impregnation, and then the solvent is removed to obtain a positive electrode lithium supplement current collector; wherein the second vacuum impregnation conditions include: a vacuum degree of 5-50 Pa, a temperature of 20-50 ℃, and an impregnation time of 5-15 h.

14. A positive electrode sheet characterized by comprising: The positive electrode lithium supplement current collector according to any one of claims 1-10 and a positive electrode active material layer arranged on the surface of the positive electrode lithium supplement current collector.

15. A lithium-ion battery, characterized by, The positive electrode tab according to claim 14.

16. An electrical device, characterized by The lithium ion battery according to claim 15.

Images