Treatment method of lithium ion battery shell, battery shell and battery

Abstract

The invention discloses a treatment method of a lithium ion battery shell, the battery shell and a battery. The treatment method comprises the following steps: S1, carrying out surface treatment on the battery shell to be treated; s2, the battery shell treated in the step S1 is put into electrolyte, a bipolar pulse power supply is adopted for high-voltage electrochemical oxidation treatment, the treatment voltage is 200-650 V, and the treatment current density is 1-10 A / dm < 2 >; s3, washing the battery shell treated in the step S2 with water, and performing hole sealing treatment; and S4, drying and curing: naturally airing or drying at the temperature of 80-120 DEG C. The method has the advantages that the surface hardness and wear resistance of the shell can be improved, good insulation performance can be provided, and the production cost can be controlled easily.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a method for treating a lithium-ion battery housing, a battery housing and a battery. Background Art

[0002] At present, there are two ways to protect the surface of lithium-ion batteries. One is to clean the battery during the manufacturing process and then cover a layer of PET protective film or blue film on the surface of the battery housing. The other is to spray UV insulating glue on the battery core to achieve the functions of insulation and battery appearance protection. The traditional film wrapping process has difficulties in controlling the film wrapping size, and has very strict requirements for the incoming materials of the PET film or blue film for film wrapping. Otherwise, poor appearance will occur, and there will be processes such as rework, resulting in waste of manufacturing costs. The UV insulating glue spraying process is a metal surface treatment solution borrowed from the automotive industry, which has problems such as environmental protection and uneven spraying. And the UV spraying process requires new equipment, and the equipment is relatively expensive, and the investment in fixed assets will also cause problems of increased costs. Summary of the Invention

[0003] Aiming at the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present invention is: how to provide a method for treating a lithium-ion battery housing that can both improve the surface hardness and wear resistance of the housing and provide good insulation performance, as well as a battery housing and a battery using this treatment method.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for treating a lithium-ion battery housing includes the following steps:

[0006] S1. Perform surface treatment on the battery housing to be treated;

[0007] S2. Put the battery housing treated in step S1 into an electrolyte solution and perform high-voltage electrochemical oxidation treatment using a bipolar pulse power supply. The treatment voltage is 200 - 650V, and the treatment current density is 1 - 10A / dm 2 ;

[0008] S3. Wash the battery housing treated in step S2 with water and perform sealing treatment;

[0009] S4. Dry and cure: Air dry naturally or bake at 80 - 120°C.

[0010] By applying a high-energy pulsed electric field (200–600 V) to break down the passivation film on the metal surface, inducing micro-plasma discharge in the micro-region (local temperature reaching 2000–8000 K), a complex electro-thermal chemical reaction occurs between the metal substrate and the electrolyte components (such as silicates and phosphates), resulting in the formation of a ceramic coating with α-Al2O3, MgO or TiO2 as the main phase. This process follows a dynamic cycle mechanism of "electrochemical oxidation - film breakdown - molten deposition", ultimately forming a gradient composite structure composed of a dense inner layer and a porous outer layer. Compared with traditional anodic oxidation treatment, the coating of this technology has significant advantages: the thickness can reach 10–200 μm, the microhardness is above 2000 HV, it has a metallurgical bond with the substrate, and has excellent wear resistance, corrosion resistance and insulation properties. In addition, this technology is compatible with the treatment of complex geometric workpieces and the electrolyte environment is friendly.

[0011] Further, in the step S2, the electrolyte contains 5–10 g / L of K2SiO3, 4–6 g / L of Na2O2, 0.5–1 g / L of NaF, 2–3 g / L of CH3COONa, 1–3 g / L of Na3VO3; the pH of the electrolyte is 11–13.

[0012] Further, in the step S2, the electrolyte contains 10–20 g / L of Na3PO4, 1–4 g / L of KOH and 10–15 g / L of Na2MoO4.

[0013] Further, in the step S1, the surface treatment steps include: first removing the grease and contaminants on the aluminum substrate surface with an alkaline or organic solvent; then removing the oxide layer and activating the surface with dilute sulfuric acid or a mixed acid solution; finally, performing a water wash.

[0014] Further, the concentration of the dilute sulfuric acid is 10%.

[0015] Further, the sealing treatment uses silicate or polymer to seal the surface micropores.

[0016] A battery case is prepared by using the treatment method for the lithium-ion battery case as described above.

[0017] A battery includes the battery case as described above.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. Greatly improves the surface hardness of the material, the microhardness is between 1000 and 2000 HV, and the highest can reach 3000 HV, which can be comparable to that of cemented carbide, far exceeding the hardness of high-carbon steel, high-alloy steel and high-speed tool steel; there is no need to worry about scratches and other defects during the production of the battery.

[0020] 2. Has good wear resistance.

[0021] 3. It has good heat resistance and corrosion resistance, and the neutral salt spray test is ≥ 1000 hours.

[0022] 4. It has good insulation performance, and the insulation resistance can reach 100 MΩ.

[0023] 5. The ceramic film grows in-situ on the substrate, with firm bonding, and the ceramic film is dense and uniform. Detailed implementation manners

[0024] The present invention will be further described in detail below in conjunction with the embodiments.

[0025] During specific implementation: A processing method for a lithium-ion battery housing, and its main process flow is as follows:

[0026] Aluminum shell housing to be processed → Chemical degreasing → Pickling activation → Water washing → High-pressure electrochemical oxidation (electrolyte + high-voltage power supply) → Water washing → Sealing holes → Drying → Final product inspection.

[0027] Embodiment 1: In this embodiment, a silicate-based electrolyte is used to process the battery housing, and three-component electrolytes are used in the experiment.

[0028] The first group: The electrolyte contains 5 g / L of K2SiO3, 4 g / L of Na2O2, 0.5 g / L of NaF, 2 g / L of CH3COONa, and 1 g / L of Na3VO3.

[0029] The second group: The electrolyte contains 7 g / L of K2SiO3, 5 g / L of Na2O2, 0.8 g / L of NaF, 2.5 g / L of CH3COONa, and 2 g / L of Na3VO3.

[0030] The third group of electrolyte contains 10 g / L of K2SiO3, 6 g / L of Na2O2, 1 g / L of NaF, 3 g / L of CH3COONa, and 3 g / L of Na3VO3.

[0031] During the experiment, 300 aluminum shell housings are used to remove the grease and contaminants on the surface of the aluminum substrate with acetone; dilute sulfuric acid (10% H2SO4) is used to remove the oxide layer and activate the surface; then the workpiece is thoroughly washed with deionized water to avoid impurity residues.

[0032] The 300 aluminum shell housings are evenly divided into three groups and respectively placed in 3 groups of electrolytes. A bipolar pulse power supply is used, and at a voltage of 450 V and a current density of 5.5 A / dm 2 , it is processed for 30 minutes; silicate is used to seal the micropores to improve the corrosion resistance, and it is dried in an environment of 80 - 120 °C.

[0033] The aluminum shell casings treated with three groups of electrolytes were respectively subjected to tests on microhardness, coating thickness, insulation resistance, and salt spray test. The test results are shown in Table 1 below.

[0034] Table 1

[0035] Group Microhardness (HV) Coating thickness (μm) Salt spray test (h) Insulation resistance (MΩ) The first group 1980 ± 85 HV 35 ± 4 μm 1020±65h 112 ± 13 MΩ The second group 2280 ± 72 HV 44 ± 5 μm 1230±80h 140 ± 15 MΩ The third group 2080 ± 90 HV 52 ± 6 μm 1220±75h 140 ± 15 MΩ

[0036] Example 2: The three electrolytes used in this example are as follows.

[0037] Component 1: The electrolyte contains 10 g / L of Na3PO4, 1 g / L of KOH, and 10 g / L of Na2MoO4.

[0038] Component 2: The electrolyte contains 15 g / L of Na3PO4, 2.5 g / L of KOH, and 12.5 g / L of Na2MoO4.

[0039] Component 3: The electrolyte contains 20 g / L of Na3PO4, 4 g / L of KOH, and 15 g / L of Na2MoO4.

[0040] During the test, 300 aluminum shell casings were also used to remove the grease and contaminants on the surface of the aluminum substrate with acetone; dilute sulfuric acid (10% H2SO4) was used to remove the oxide layer and activate the surface; then the workpiece was thoroughly cleaned with deionized water to avoid residue of impurities.

[0041] The 300 aluminum shell casings were evenly divided into three groups and were respectively placed into three groups of electrolytes. A bipolar pulse power supply was used, and at a voltage of 450 V and a current density of 6 A / dm 2 , they were processed for 25 minutes; silicate was used to seal the micropores to improve the corrosion resistance, and they were dried in an environment of 80 - 120 °C.

[0042] The aluminum shell casings treated with three groups of electrolytes were respectively subjected to tests on microhardness, coating thickness, insulation resistance, and salt spray test. The test results are shown in Table 2 below.

[0043] Table 2

[0044] Group Microhardness (HV) Coating thickness (μm) Salt spray test (h) Insulation resistance (MΩ) The first group 2050 ± 110 HV 28 ± 3 μm 1500±120h 105 ± 15 MΩ The second group 2350 ± 95 HV 41 ± 4 μm 1800±100h 150 ± 13 MΩ The third group 2180 ± 120 HV 50 ± 6 μm 1850±150h 150 ± 16 MΩ

[0045] During specific implementation, the treatment process of the above lithium-ion battery casing is set after the stretching and cleaning process of the battery casing, which can save two steps of chemical degreasing and pickling activation, and is directly connected to the water washing section of the aluminum shell manufacturing process for continuous production.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for treating a lithium-ion battery housing, characterized in that, It includes the following steps: S1. Perform surface treatment on the battery case to be processed; S2. Place the battery housing processed in step S1 into the electrolyte and perform high-voltage electrochemical oxidation treatment using a bipolar pulse power supply. The treatment voltage is 200 - 650 V, and the treatment current density is 1 - 10 A / dm 2 ; S3. Wash the battery case processed in step S2 and perform hole sealing treatment; S4. Drying and curing: Air dry naturally or dry at 80 - 120 °C.

2. The method for treating a lithium-ion battery housing according to claim 1, wherein In the said step S2, the electrolyte contains 5 - 10 g / L of K2SiO3, 4 - 6 g / L of Na2O2, 0.5 - 1 g / L of NaF, 2 - 3 g / L of CH3COONa, 1 - 3 g / L of Na3VO3; the pH of the electrolyte is 11 - 13.

3. The processing method of the lithium-ion battery housing according to claim 1, characterized in that, In the said step S2, the electrolyte contains 10 - 20 g / L of Na3PO4, 1 - 4 g / L of KOH and 10 - 15 g / L of Na2MoO4.

4. The method for treating a lithium-ion battery housing according to claim 1, characterized in that, In the said step S1, the steps of surface treatment include: first remove the grease and contaminants on the surface of the aluminum substrate with an alkaline or organic solvent; then remove the oxide layer and activate the surface with dilute sulfuric acid or a mixed acid solution; finally perform water washing.

5. The method for treating a lithium-ion battery housing according to claim 1, characterized in that, The hole sealing treatment uses silicate or polymer to seal the surface micropores.

6. A battery housing, characterized in that, It is prepared by using the treatment method of the lithium-ion battery case as described in any one of claims 1 - 6.

7. A battery, characterized in that, It includes the battery case as described in claim 7.