Semi-solid-state battery, and preparation method therefor and use thereof

Abstract

The present invention provides a semi-solid-state battery, and a preparation method therefor and the use thereof. The preparation method comprises the following steps: 1) performing a curing treatment on a battery after liquid injection under 50-70°C and 500-2000 kg / f for 12-48 h, so as to obtain a cured battery; and 2) performing a formation treatment on the cured battery, so as to obtain a semi-solid battery. The semi-solid-state battery provided in the present invention has excellent low-temperature performance.

Description

A semi-solid battery and a preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to a semi-solid battery and a preparation method and application thereof, and belongs to the technical field of batteries. BACKGROUND

[0002] The semi-solid battery is a special type of battery, which contains both liquid electrolyte and solid electrolyte inside. During charging and discharging, ions are transported through solid and liquid electrolytes to achieve the purpose of storing and releasing energy. The semi-solid battery has the advantages of high energy density, high temperature stability, fast charging and excellent cycle performance, and is favored in the fields of vehicle power batteries and energy storage.

[0003] However, the low temperature performance of the semi-solid battery is low, which limits the popular use of such batteries in cold regions. The common solution at present is to configure a circulating heating device outside the battery to improve the operating temperature of the semi-solid battery, thereby improving the discharge performance of such batteries in low temperature environment, but this method only physically heats the semi-solid battery, and the addition of the heating device reduces the energy density of the semi-solid battery.

[0004] Therefore, it is urgent to explore a technical solution to fundamentally solve the low temperature performance of the semi-solid battery. SUMMARY

[0005] The present application provides a preparation method of a semi-solid battery, which is simple to operate and can prepare a semi-solid battery with excellent low temperature performance.

[0006] The present application provides a semi-solid battery prepared by the above preparation method, which has excellent low temperature performance.

[0007] The present application also provides an electronic device comprising the above semi-solid battery, so that the electronic device also has excellent use performance in a low temperature environment.

[0008] In one aspect, the present application provides a preparation method of a semi-solid battery, comprising the following steps:

[0009] 1) curing the battery after liquid injection at 50-70 DEG C, 500-2000 kg / f for 12-48 h to obtain a cured battery;

[0010] 2) performing formation treatment on the cured battery to obtain a semi-solid battery.

[0011] The preparation method described above, in step 1), the curing treatment temperature is 60-70 DEG C, the pressure is 1000-2000 kg / f, and the time is 12-24 h.

[0012] The electrolyte before the solidification treatment comprises a lithium salt, a solvent, and an additive.

[0013] The lithium salt comprises LiPF6, and the mass percentage of LiPF6 is 9-13 wt.%.

[0014] In step 2), the formation temperature of the formation treatment is 35-45℃, and the extrusion pressure is 1000 kg / f (4-6h).

[0015] The preparation method further comprises a first standing treatment before the solidification treatment, the temperature of the first standing treatment is 20-30℃, and the standing time is 24-72h.

[0016] The preparation method further comprises a second standing treatment after the formation treatment, the temperature of the second standing treatment is 25℃, and the standing time is 24-72h.

[0017] The preparation method further comprises a positive plate, the positive plate comprises a positive slurry,

[0018] The positive slurry comprises lithium iron phosphate, conductive carbon black, conductive slurry, binder, and 1%-2% LATP.

[0019] The application further provides a semi-solid battery prepared by the preparation method.

[0020] The application further provides an electronic device comprising the semi-solid battery.

[0021] The preparation method of the semi-solid battery provided by the application realizes the solidification treatment of the battery after liquid injection by controlling specific pressure and temperature, and then performs formation treatment on the solidified battery to obtain a semi-solid battery, which has excellent low-temperature performance.

[0022] The semi-solid battery prepared by the preparation method has excellent low-temperature performance.

[0023] The electronic device provided by the application comprises the semi-solid battery, and therefore can still have good use performance in a low-temperature environment. BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a comparison chart of the semi-solid batteries provided by the embodiments 1-4 at 5℃ low-temperature charging.

[0025] FIG. 2 is a comparison chart of the semi-solid batteries provided by the embodiments 1-4 at 5℃ low-temperature discharging. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0027] The present application provides a preparation method of a semi-solid battery, comprising the following steps: 1) performing solidification treatment on the battery after injection at 50-70℃ and 500-2000kg / f for 12-48h to obtain a solidified battery; and 2) performing formation treatment on the solidified battery to obtain a semi-solid battery.

[0028] The preparation method provided by the present application is used for preparing a semi-solid battery. The solidification treatment of the battery is realized by controlling the temperature and the pressure. Subsequently, the formation treatment is performed on the solidified battery to obtain a semi-solid battery. The semi-solid battery has excellent low-temperature performance.

[0029] In detail, in step 1), the temperature of the solidification treatment includes but is not limited to 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, 62℃, 64℃, 66℃, 68℃, 70℃ or a range formed by any two of them, and the pressure of the solidification treatment includes but is not limited to 500kg / f, 800kg / f, 1000kg / f, 1200kg / f, 1400kg / f, 1600kg / f, 1800kg / f, 2000kg / f or a range formed by any two of them.

[0030] It can be understood that the positive electrode sheet, the negative electrode sheet, the separator and the current collector need to be assembled first to form an assembled battery. The present application does not limit the specific process of assembling the battery, and the battery can be assembled by using the conventional process in the art.

[0031] The injection treatment is performed on the assembled battery, that is, the electrolyte is injected into the assembled battery to obtain a battery after injection. The present application also does not limit the specific process of the injection treatment.

[0032] In a specific embodiment, the soft package battery is injected. First, a monomer solution containing a certain lithium salt concentration is prepared. Then, a thermal initiator is added to the above solution to obtain a precursor solution. Then, the battery is assembled according to the assembly method of the liquid battery. Specifically, the injection amount of each battery cell is 20-25g.

[0033] In the curing process, the battery after curing can be disassembled to obtain the temperature range at which the battery can be substantially cured, or the softness of the soft-pack battery can be felt by hand, if the battery is hard, the effective curing is obtained, and the electrolyte in the battery is in a stable state, which improves the stability of the electrolyte in the battery.

[0034] In step 2), the battery after curing is subjected to formation treatment, so that the positive electrode and the negative electrode of the battery form a stable structure under the wrapping of the electrolyte, and the electrodes can effectively embed and release ions to achieve good charge and discharge cycle performance.

[0035] The preparation method provided by the application can prepare a semi-solid battery with excellent low-temperature performance. The inventors believe that the reason may be that, in the preparation process, the battery after liquid injection is subjected to pressure and temperature curing, so that the curing is more complete and thorough under a certain temperature and pressure, the electrolyte forms a more stable structure, that is, a thermal initiation method, which reduces the flowability and volatility of the electrolyte in a low-temperature environment, and further reduces the internal resistance of the battery and improves the low-temperature conductivity of the battery. On the other hand, the pressure and temperature curing can press the small amount of gas generated in the curing process into the air bag, avoiding the impedance caused by the gas, and further reducing the internal resistance of the battery.

[0036] Further, in a specific embodiment of the application, the temperature of the curing treatment is 60-70℃, the pressure is 500-1000kg / f, and the time is 12-24h.

[0037] In detail, the temperature of the curing treatment includes but is not limited to 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, or a range between any two of them.

[0038] The pressure of the curing treatment includes but is not limited to 500kg / f, 550kg / f, 600kg / f, 650kg / f, 700kg / f, 750kg / f, 800kg / f, 850kg / f, 900kg / f, 950kg / f, 1000kg / f, or a range between any two of them.

[0039] The time of the curing treatment includes but is not limited to 12h, 14h, 16h, 18h, 20h, 22h, 24h, or a range between any two of them.

[0040] When the temperature, pressure and time of the solidification treatment meet the above-mentioned limitations, the liquid precursor can well infiltrate the electrode during in-situ polymerization, forming a more intimate interfacial contact. Under the action of external conditions (temperature and pressure) and initiators, the polymerizable functional groups in the precursor solution undergo polymerization, thereby forming a polymer electrolyte in-situ, further improving the low-temperature performance of the battery.

[0041] Further, in a specific embodiment of the present application, the electrolyte before the solidification treatment comprises a lithium salt, a solvent, an additive.

[0042] In detail, the lithium salt comprises but is not limited to at least one of LiTFSI, LiPF6, LiFSI, LiBOB, LiBF4, LiDFOB, LiBOB, the solvent comprises but is not limited to at least one of PC, EC, DMC, DEC, EMC, and the additive comprises but is not limited to at least one of a conductive additive, an overcharge protection additive, a flame retardant additive.

[0043] In a specific embodiment, the electrolyte before the solidification treatment comprises LiPF6, LiFSI, EC, EMC, DMC, VC, FEC.

[0044] It can be understood that LiPF6 can provide ionic conductivity and also adjust the stability of the electrolyte, and the mass percentage of LiPF6 in the electrolyte is closely related to the performance.

[0045] Further, in a specific embodiment of the present application, the lithium salt comprises LiPF6, and the mass percentage of LiPF6 is 9wt.%-13wt.%.

[0046] In detail, the mass percentage of LiPF6 in the electrolyte comprises but is not limited to 9wt.%, 9.5wt.%, 10wt.%, 10.5wt.%, 11wt.%, 11.5wt.%, 12wt.%, 12.5wt.%, 13wt.% or a range consisting of any two of them.

[0047] When the mass percentage of LiPF6 is within the above-mentioned range, not only can it support ion transfer during battery charging and discharging, but also can provide better battery cycle life, charging and discharging efficiency and temperature characteristics, and improve low-temperature performance.

[0048] Further, in a specific embodiment of the present application, in step 2), the temperature of the formation treatment is 35-45°C, and the extrusion pressure is 1000kg / f.

[0049] In detail, the temperature of the formation treatment includes, but is not limited to, 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, or a range formed by any two of them.

[0050] The formation treatment of the present application adopts a constant current charging mode, and the charging current is 110-550 mA.

[0051] The present application does not limit the time of the formation treatment, and the appropriate time can be selected according to the actual situation. In a specific embodiment, the time of the formation treatment is 4-6 h.

[0052] When the temperature of the formation treatment is in the above range, not only can the solidification of the battery in the formation stage be prevented due to the excessively high temperature, but also the formation can be effectively carried out. At the same time, the extrusion pressure of 1000 kg / f can make the battery form the SEI film better through extrusion, so that the battery is more stable, and the process of improving the charge-discharge performance and the comprehensive performance such as self-discharge and storage of the battery is further improved.

[0053] Further, in a specific embodiment of the present application, the solidification treatment further includes a first standing treatment before the solidification treatment, and the temperature of the first standing treatment is 20-30℃, and the time is 24-72 h.

[0054] In detail, the temperature of the first standing treatment includes, but is not limited to, 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, or a range formed by any two of them. The time includes, but is not limited to, 24 h, 30 h, 35 h, 40 h, 45 h, 50 h, 55 h, 60 h, 65 h, 70 h, 72 h, or a range formed by any two of them.

[0055] The first standing treatment of the battery before the solidification treatment in the above temperature and time range can make the internal stress gradually release, thereby reducing the internal deformation or stress concentration problem that may occur in the formation or solidification process. This helps to improve the manufacturing quality and performance stability of the solid-state battery.

[0056] Further, in a specific embodiment of the present application, the formation treatment further includes a second standing treatment after the formation treatment, and the temperature of the second standing treatment is 20-30℃, and the time is 24-72 h.

[0057] In detail, the temperature of the first standing treatment includes, but is not limited to, 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, or a range formed by any two of them. The time includes, but is not limited to, 24 h, 30 h, 35 h, 40 h, 45 h, 50 h, 55 h, 60 h, 65 h, 70 h, 72 h, or a range formed by any two of them.

[0058] The second standing treatment is performed after the formation treatment according to the above-mentioned temperature and time, so as to ensure that the structure and chemical properties formed in the formation process can stably exist under a wider range of temperature and environmental conditions. At the same time, it is helpful to further reduce the stress inside the battery and improve the overall stability and performance of the battery.

[0059] Further, in a specific embodiment of the present application, the battery after liquid injection includes a positive electrode sheet, and the positive electrode sheet includes a positive electrode slurry, and the positive electrode slurry includes lithium iron phosphate, conductive carbon black, a binder, and 1%-2% of LATP.

[0060] In the present application, the binder includes any one or a combination of at least two of polyvinylidene fluoride, polyethylene oxide, polyvinyl alcohol, polyurethane, polyacrylic acid, sodium carboxymethyl cellulose, or polyacrylonitrile.

[0061] 1%-2% of LATP refers to the mass percentage of LATP in the positive electrode slurry being 1%-2%, and in detail, the mass percentage of LATP in the positive electrode slurry includes but is not limited to 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, or a range formed by any two of them.

[0062] The present application does not limit the preparation process of the positive electrode slurry coated on the positive electrode sheet, and a conventional process in the art can be used.

[0063] In a specific embodiment, the positive electrode slurry is extrusion coated on the AB surface of the carbon-coated aluminum foil, and the surface density is 345±4 g / m 2 and baking to avoid transverse cracking and solvent dripping. The LATP doped in the positive electrode slurry has high electrical conductivity, which is beneficial to the construction of an ion-conducting network, and shortens the diffusion path of electrons and ions. The material with a large specific surface area helps to pass through lithium ions, further accelerating the ion transmission rate and improving the low-temperature performance.

[0064] In another aspect of the present application, a semi-solid battery is provided, which is prepared by the above-mentioned preparation method.

[0065] Since the battery is prepared by the above-mentioned preparation method, it has good low-temperature performance.

[0066] In another aspect of the present application, an electronic device is provided, which includes the semi-solid battery as described above.

[0067] The present application does not limit the specific type of electronic device, as long as it includes the semi-solid battery as described above.

[0068] In a specific embodiment, the electronic device is a drone, and in another specific embodiment, the electronic device is a new energy vehicle; and in another specific embodiment, the electronic device is a smart wearable device.

[0069] Since the electronic device provided by the application comprises the semi-solid battery as described above, the electronic device still has good use performance in a relatively cold area.

[0070] Hereinafter, the semi-solid battery provided by the application is described through specific examples.

[0071] Example 1

[0072] The preparation method of the semi-solid battery provided by the present embodiment comprises the following steps:

[0073] 1. Liquid injection: inject the electrolyte containing the semi-solid additive into the assembled battery, and the mass ratio of the additive and the electrolyte is 3:97;

[0074] The positive electrode plate of the assembled battery comprises: the positive electrode plate main material is lithium iron phosphate, the binder is polyethylene oxide, and the conductive agent is carbon black, and the mass ratio is 96:2.2:1.8;

[0075] The negative electrode plate of the assembled battery comprises: the negative electrode plate main material is graphite, the binder is styrene-butadiene rubber, and the conductive agent is carbon black, and the mass ratio is 96.1:1.8:2.1;

[0076] The composition of the injected electrolyte is EC, EMC, DMC, LiPF6, LiFSI, VC, and FEC with a mass ratio of 34.2:41.8:8.5:9.5:3.0:2.5:0.5.

[0077] 2. Curing: the battery after liquid injection is subjected to first standing treatment at 25℃ for 48h, and then subjected to curing treatment, the curing temperature is 60℃, the applied pressure is 1000kg / f, and the curing time is 12h, to obtain the cured battery.

[0078] 3. Formation: the cured battery is subjected to constant current charging at a charging current of 110mA, the formation temperature is 35℃, the extrusion pressure is 1000kg / f, and the formation time is 5h, to obtain the formed battery.

[0079] 4. Second sealing: first, the air bag is punctured by a knife, and vacuum is applied at the same time, so that the gas and a small part of the electrolyte in the air bag are extracted, and then the second sealing head is immediately sealed in the second sealing area to ensure the air tightness of the battery, and finally the sealed battery is cut off from the air bag.

[0080] 5, Capacity distribution: the battery is distributed in the capacity distribution cabinet after the sealing is completed. In the battery manufacturing process, different battery monomers may have slight differences. The battery capacity distribution improves the overall performance and life of the battery pack by accurately measuring and classifying these differences, and finally obtains the semi-solid battery.

[0081] Embodiment 2

[0082] The preparation method of the semi-solid battery provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0083] In step 2), the solidification temperature is 70℃, and the applied pressure is 1000kg / f.

[0084] Embodiment 3

[0085] The preparation method of the semi-solid battery provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0086] In step 2), the solidification time is 24h.

[0087] Embodiment 4

[0088] The preparation method of the semi-solid battery provided in this embodiment is basically the same as that in Embodiment 2, except that:

[0089] In step 2), the solidification time is 24h.

[0090] Embodiment 5

[0091] The preparation method of the semi-solid battery provided in this embodiment includes the following steps:

[0092] 1, Liquid injection: inject the electrolyte containing the semi-solid additive into the assembled battery, and the mass ratio of the additive and the electrolyte is 3:97;

[0093] The positive electrode sheet of the assembled battery includes: the positive electrode sheet main material is lithium iron phosphate, the binder is polyethylene oxide, and the conductive agent is carbon black, and the mass ratio is 96:2.2:1.8;

[0094] The negative electrode sheet of the assembled battery includes: the negative electrode sheet main material is graphite, the binder is styrene butadiene rubber, and the conductive agent is carbon black, and the mass ratio is 96.1:1.8:2.1;

[0095] The composition of the injected electrolyte is EC, EMC, DMC, LiPF6, LiFSI, VC, FEC with a mass ratio of 34.2:41.8:8.5:9.5:3.0:2.5:0.5.

[0096] 2, curing: the completed battery is placed at 30 °C for the first standing treatment, the standing time is 48 h, then curing treatment is carried out, the curing temperature is 50 °C, the applied pressure is 1000 kg / f, the curing time is 36 h, and the cured battery is obtained.

[0097] 3, formation: the cured battery is charged at a constant current of 110 mA, the formation temperature is 35 °C, the extrusion pressure is 1000 kg / f, and the formation time is 5 h, and the formed battery is obtained. The formed battery is subjected to a second standing treatment, the temperature is 20 °C, and the time is 48 h.

[0098] 4, sealing: first, the air bag is punctured by a cutter, and vacuum is applied, so that the gas and a small amount of electrolyte in the air bag are extracted, then the sealing head is immediately sealed in the sealing area to ensure the airtightness of the battery, and finally the sealed battery is cut off the air bag.

[0099] 5, capacity: the sealed battery is subjected to capacity test in a capacity test cabinet. In the battery manufacturing process, different battery monomers may have slight differences, and battery capacity test can improve the overall performance and life of the battery pack by accurately measuring and classifying these differences, and finally the semi-solid battery is obtained.

[0100] Example 6

[0101] The preparation method of the semi-solid battery provided in this embodiment is basically the same as that in example 1, except that:

[0102] In step 2), the curing treatment is carried out at a temperature of 50 °C and a pressure of 500 kg / f for 48 h.

[0103] Example 7

[0104] The preparation method of the semi-solid battery provided in this embodiment is basically the same as that in example 1, except that:

[0105] In step 1), the composition of the electrolyte is EC, EMC, DMC, LiPF6, LiFSI, VC and FEC with a mass ratio of 26.5:45.5:8.5:13.5:3.0:2.5:0.5.

[0106] Example 8

[0107] The preparation method of the semi-solid battery provided in this embodiment is basically the same as that in example 1, except that:

[0108] In step 3), the formation treatment is carried out at a formation temperature of 30 °C and an extrusion pressure of 800 kg / f.

[0109] Comparative example 1

[0110] The preparation method of the semi-solid battery provided in this comparative example is basically the same as that in Example 1, except that:

[0111] In step 2), no pressure treatment is performed during the curing process, and there is no pressure.

[0112] Comparative Example 2

[0113] The preparation method of the semi-solid battery provided in this comparative example is basically the same as that in Example 1, except that:

[0114] In step 2), the temperature during the curing process is 45℃, the pressure is 2500kg / f, and the time is 24h.

[0115] Comparative Example 3

[0116] The preparation method of the semi-solid battery provided in this comparative example is basically the same as that in Example 1, except that:

[0117] In step 2), the temperature during the curing process is 75℃, the pressure is 450kg / f, and the time is 12h.

[0118] Test Example

[0119] The semi-solid batteries provided in all examples and comparative examples are tested, including the following steps:

[0120] a) Initialize the battery cell discharge;

[0121] b) The battery cell is placed at (5±2)℃ for 20h;

[0122] c) At (5±2)℃, the battery cell is charged at P constant power to the charge termination voltage of any single cell or module, and is placed for 30min;

[0123] d) At (5±2)℃, the battery cell is discharged at P constant power to the discharge termination voltage of the battery cell;

[0124] e) Record the charge energy, discharge energy, charge time, discharge time, charge capacity, and discharge capacity of c) and d); calculate the energy efficiency; calculate the energy retention rate of the charge energy and the discharge energy relative to the initial charge energy and the initial discharge energy, respectively.

[0125] The specific test results are shown in Table 1, wherein Figure 1 is a comparison chart of 5℃ low-temperature charging of Examples 1-4, and Figure 2 is a comparison chart of 5℃ low-temperature discharging of Examples 1-4.

[0126] Table 1

[0127] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for producing a semi-solid battery, characterized by, The method comprises the following steps: 1) performing a curing treatment on the battery after injecting electrolyte at 50-70℃ and 500-2000kg / f for 12-48h to obtain a cured battery; 2) performing a formation treatment on the cured battery to obtain a semi-solid battery.

2. The production method according to claim 1, characterized by, In step 1), the curing treatment is performed at 60-70℃, 1000-2000kg / f for 12-24h.

3. The production method according to claim 1 or 2, characterized by, The electrolyte before the curing treatment comprises a lithium salt, a solvent and an additive.

4. The production method according to claim 3, characterized by, The lithium salt comprises LiPF6, and the mass percentage of LiPF6 is 9wt.%-13wt.%.

5. The production method according to any one of claims 1 or 2, characterized by, In step 2), the formation temperature of the formation treatment is 35-45℃, and the extrusion pressure is 1000kg / f.

6. The production method according to any one of claims 1 or 2, characterized by, The curing treatment further comprises a first standing treatment before the curing treatment, and the first standing treatment is performed at 20-30℃ for 24-72h.

7. The production method according to any one of claims 1 or 2, characterized by, The formation treatment further comprises a second standing treatment after the formation treatment, and the second standing treatment is performed at 25℃ for 24-72h.

8. The method of any one of claim 1, wherein, The battery after injecting electrolyte comprises a positive electrode sheet, and the positive electrode sheet comprises a positive electrode slurry, The positive electrode slurry comprises lithium iron phosphate, conductive carbon black, conductive slurry, binder and 1%-2% LATP.

9. A semi-solid battery, characterized by, The semi-solid battery is prepared by the preparation method in any one of claims 1-8.

10. An electronic device, comprising: The semi-solid battery in claim 9.

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