Semi-solid lithium ion battery

Abstract

The invention discloses a semi-solid lithium ion battery, which comprises a positive electrode, a negative electrode, a positive electrode, a negative electrode and a positive electrode, the formula of the positive electrode comprises 90%-98% of an active substance, 2%-6% of a solid electrolyte, 0.5%-2% of a conductive agent and 0.5%-3% of an adhesive; the formula of the negative electrode comprises 90%-98% of an active substance, 1%-5% of a thickening agent, 0.5%-2% of a conductive agent and 1%-3% of an adhesive; the diaphragm is coated with a 2C + 12 + 2LATP coating; and a high-concentration electrolyte with a lithium salt concentration of 3.0 to 3.5 mol. According to the semi-solid-state lithium ion battery, an optimized positive electrode and negative electrode material formula is adopted, and a proper amount of solid electrolyte is added into the positive electrode and the negative electrode, so that the ionic conductivity and the thermal stability of the battery are further improved. And moreover, by using the high-concentration lithium salt electrolyte and the improved diaphragm technology, the battery has better electrochemical performance and longer cycle life in the charge-discharge process.

Description

Technical Field

[0001] The present invention relates to the field of lithium ion batteries, and in particular to a semi-solid lithium ion battery. Background Art

[0002] With the development of science and technology, lithium-ion batteries have been widely used in portable electronic devices, electric vehicles and energy storage systems. However, traditional liquid lithium-ion batteries are prone to safety hazards such as fire and explosion during the charging and discharging process due to the flammable liquid electrolytes they use. In addition, the poor performance stability of liquid electrolytes in high and low temperature environments further limits their application scope.

[0003] As a new type of battery technology, semi-solid lithium-ion batteries significantly improve the safety performance of batteries while maintaining high energy density by combining liquid electrolytes and solid electrolytes. Semi-solid batteries fundamentally solve the safety problems of traditional liquid batteries by reducing the proportion of liquid electrolytes and introducing non-flammable solid electrolytes. In addition, semi-solid batteries also have excellent cycle performance and high and low temperature performance, and can work stably under a wider range of environmental conditions. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a semi-solid lithium-ion battery, which not only improves the safety of the battery, but also improves the overall performance of the battery, and is suitable for various application scenarios requiring high safety, high energy density and long life.

[0005] The present invention is achieved through the following technical solutions: a semi-solid lithium-ion battery, comprising:

[0006] A positive electrode having a formulation comprising 90% to 98% of an active material, 2% to 6% of a solid electrolyte, 0.5% to 2% of a conductive agent, and 0.5% to 3% of a binder;

[0007] a negative electrode having a formulation comprising 90% to 98% of an active material, 1% to 5% of a thickener, 0.5% to 2% of a conductive agent, and 1% to 3% of a binder;

[0008] A diaphragm coated with a 2C+12+2LATP coating;

[0009] A high concentration electrolyte having a lithium salt concentration of 3.0 to 3.5 molar.

[0010] As a preferred technical solution, the method for preparing the positive electrode comprises the following steps:

[0011] Baking the positive electrode material at 70°C to 90°C for 4 to 8 hours;

[0012] Stirring at 15 to 25 rpm for 5 to 10 minutes, then stirring at 50 to 100 rpm for 3 to 5 hours;

[0013] Add the solid electrolyte and the conductive agent, stir at 15 to 25 rpm for 5 to 10 minutes, and then stir at 50 to 100 rpm for 1 to 2 hours;

[0014] The slurry was stirred under vacuum and the viscosity was adjusted to 3000 to 7000 mPa·s.

[0015] As a preferred technical solution, the method for preparing the negative electrode comprises the following steps:

[0016] baking the negative electrode material at 50°C to 70°C;

[0017] The active material, thickener, conductive agent, binder and solid electrolyte are mixed in proportion;

[0018] Stirring at 15 to 25 rpm for 5 to 10 minutes, then stirring at 50 to 100 rpm for 2 to 4 hours;

[0019] The slurry was stirred under vacuum and the viscosity was adjusted to 3000 to 7000 mPa·s.

[0020] As a preferred technical solution, the method for preparing the diaphragm comprises the following steps:

[0021] Apply 2C+12+2LATP coating;

[0022] The membrane is dried at a moderate temperature.

[0023] As a preferred technical solution, the method for preparing the electrolyte comprises the following steps:

[0024] preparing a high concentration electrolyte having a lithium salt concentration of 3.0 to 3.5 molar;

[0025] The solvent composition is adjusted as needed to enhance the wettability and liquid absorption of the negative electrode.

[0026] As a preferred technical solution, the positive electrode active material is selected from at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide.

[0027] As a preferred technical solution, the solid electrolyte is Li1+xAlxTi2-x(PO4)3(LATP).

[0028] As a preferred technical solution, the diaphragm is a polyolefin diaphragm, and solid electrolyte coatings are coated on both sides of the diaphragm.

[0029] The beneficial effects of the present invention are as follows: firstly, by introducing solid electrolytes into the positive and negative electrode materials, the proportion of flammable liquid electrolytes used is greatly reduced, the safety performance of the battery is fundamentally improved, and the risk of fire and explosion of traditional liquid batteries in the case of needle puncture, extrusion, short circuit, etc. is avoided;

[0030] Secondly, the solid electrolyte LATP (Li1+xAlxTi2-x(PO4)3) used has high ionic conductivity and a wide electrochemical window, which significantly improves the ionic conduction efficiency of the battery, and enhances the energy density and electrochemical performance of the battery. In addition, the use of high-concentration lithium salt electrolyte further enhances the stability of the battery in high and low temperature environments, allowing the battery to maintain excellent performance in a wider operating temperature range;

[0031] By optimizing the formula of the positive electrode and the negative electrode, combined with an improved manufacturing process, the semi-solid lithium-ion battery of the present invention also performs well in terms of cycle life and charge and discharge rate. The battery can still maintain a high capacity retention rate after long-term cycle use, meeting the application requirements for high battery life and performance.

[0032] Combining the above advantages, the semi-solid lithium-ion battery of the present invention not only has significant improvements in safety and performance, but also has a longer service life and better environmental adaptability. It is suitable for a variety of high-demand application scenarios such as portable electronic devices, electric vehicles, energy storage systems, etc., and has broad market prospects and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0035] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0036] Any feature disclosed in this specification (including any additional claims, abstract and drawings), unless otherwise stated, may be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0037] like Figure 1 As shown, the present invention provides a semi-solid lithium ion battery, which includes a positive electrode, a negative electrode, a separator and an electrolyte. The positive electrode material includes an active substance, a solid electrolyte, a conductive agent and a binder. The active substance is selected from lithium cobalt oxide, lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide; the solid electrolyte is Li1+xAlxTi2-x(PO4)3(LATP);

[0038] The conductive agent includes JLK-CS15 and super-P; the adhesive is Solf-5130;

[0039] The negative electrode material includes an active material, a thickener, a conductive agent and a binder;

[0040] The active material is selected from graphite or other suitable materials; the thickener is CMC; the conductive agent is carbon black; and the binder is SBR. The diaphragm is a polyolefin diaphragm coated with a 2C+12+2LATP coating. The electrolyte is a high-concentration lithium salt electrolyte, and the lithium salt concentration is 3.0 to 3.5 moles.

[0041] The preparation method of the positive electrode comprises the following steps:

[0042] First, bake the positive electrode material at 80°C for 6 hours and wait until the temperature drops below 60°C for use. Then, stir at 18.6 rpm for 5 minutes and at 74.4 rpm for 3 to 4 hours. Next, add the solid electrolyte and conductive agent, stir at 18.6 rpm for 5 minutes and at 74.4 rpm for 1 hour. Finally, vacuum stir and adjust the slurry viscosity to 4000 to 6000 mPa·s.

[0043] The method for preparing the negative electrode comprises the following steps:

[0044] First, the negative electrode material was baked at 60°C. Then, the active material, thickener, conductive agent, binder and solid electrolyte were mixed in proportion and stirred at 18.6 rpm for 5 minutes and then at 74.4 rpm for 3 hours. Finally, vacuum stirring was performed to adjust the slurry viscosity to 4000 to 6000 mPa·s.

[0045] The preparation method of the diaphragm comprises the following steps: coating a 2C+12+2LATP coating on a polyolefin diaphragm and drying the coating at an appropriate temperature.

[0046] The preparation method of the electrolyte comprises the following steps:

[0047] First, a high-concentration electrolyte with a lithium salt concentration of 3.0 to 3.5 molar is prepared. Then, the solvent composition is adjusted as needed to enhance the wettability and liquid absorption of the negative electrode.

[0048] The assembly method of the semi-solid lithium-ion battery comprises the following steps: firstly, the positive electrode, the negative electrode, the separator and the electrolyte are prepared according to the above method. Then, the positive electrode, the negative electrode and the separator are assembled into a battery, and the electrolyte is injected to finally prepare the semi-solid lithium-ion battery.

[0049] The first test results are as follows:

[0050]

[0051] Conclusion: After the solid electrolyte is mixed with the positive electrode, the positive electrode's specific capacity is normal. The 28-day charge retention capacity is as follows:

[0052]

[0053] High temperature and high humidity storage test, as shown in the following table:

[0054]

[0055] 70 degrees 48H high temperature storage test, as shown in the following table:

[0056]

[0057] The magnification test is as follows:

[0058]

[0059] The cycle test performance is as follows:

[0060]

[0061] The test steps are as follows:

[0062] Take 3 pcs of batteries and randomly label them as 4#, 5#, and 6#, then charge them at a constant current of 0.2CA until the limiting voltage is 4.05V, then change to constant voltage charging, and stop charging when the cut-off current is 0.02CA; put the fully charged numbered batteries on the test platform, adjust the descending speed of the test press needle to about 3mm / s, and the diameter of the rustless steel needle to 3.0mm, then adjust the pressure of the press to an appropriate range, put the protective plate in place, turn on the switch, let the press needle descend, and pierce the battery.

[0063] After the experiment, check the appearance of the battery.

[0064] Semi-solid (solid-liquid combination solution) can solve the safety risks of liquid battery puncture, extrusion, short circuit fire, etc. It is suitable for low-power conventional lithium batteries and has good comprehensive safety performance. It can be used as a selling point in the high-safety battery market in the future to enhance the competitiveness of related markets.

[0065] In view of the poor performance of the third iteration test (high rate discharge, ultra-high temperature resistance), subsequent optimization will be continued; preliminary research and improvement will be carried out to achieve multi-market and multi-field applications, thereby enhancing product competitiveness.

[0066] The present invention mainly improves the safety performance of the battery through the application of LATP. LATP: Li1+xAlxTi2-x(PO4)3 (Lithium Aluminum Titanium Phosphate) is a solid electrolyte material with a NASICON (sodium superionic conductor) structure, which has high ionic conductivity and a wide electrochemical window. It replaces part of the electrolyte function through solid-state ion conduction.

[0067] Through the above method, the semi-solid lithium-ion battery of the present invention has significant advantages in safety, energy density and cycle life, and is suitable for a variety of application scenarios requiring high safety and high performance. The battery fundamentally improves the safety of the battery and reduces the risk of fire and explosion by reducing the proportion of liquid electrolyte and introducing non-flammable solid electrolyte;

[0068] In addition, by optimizing the formula design of the positive and negative electrodes and combining it with an improved manufacturing process, the battery performs well in terms of cycle life and charge and discharge rate, and can maintain a high capacity retention rate after long-term cyclic use.

[0069] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. A semi-solid lithium-ion battery, characterized in that: include: A positive electrode having a formulation comprising 90% to 98% of an active material, 2% to 6% of a solid electrolyte, 0.5% to 2% of a conductive agent, and 0.5% to 3% of a binder; a negative electrode having a formulation comprising 90% to 98% of an active material, 1% to 5% of a thickener, 0.5% to 2% of a conductive agent, and 1% to 3% of a binder; A diaphragm coated with a 2C+12+2LATP coating; A high concentration electrolyte having a lithium salt concentration of 3.0 to 3.5 molar.

2. The semi-solid lithium-ion battery according to claim 1, characterized in that: The preparation method of the positive electrode comprises the following steps: Baking the positive electrode material at 70°C to 90°C for 4 to 8 hours; Stirring at 15 to 25 rpm for 5 to 10 minutes, then stirring at 50 to 100 rpm for 3 to 5 hours; Add the solid electrolyte and the conductive agent, stir at 15 to 25 rpm for 5 to 10 minutes, and then stir at 50 to 100 rpm for 1 to 2 hours; The slurry was stirred under vacuum and the viscosity was adjusted to 3000 to 7000 mPa·s.

3. The semi-solid lithium-ion battery according to claim 1, characterized in that: The method for preparing the negative electrode comprises the following steps: baking the negative electrode material at 50°C to 70°C; The active material, thickener, conductive agent, binder and solid electrolyte are mixed in proportion; Stirring at 15 to 25 rpm for 5 to 10 minutes, then stirring at 50 to 100 rpm for 2 to 4 hours; The slurry was stirred under vacuum and the viscosity was adjusted to 3000 to 7000 mPa·s.

4. The semi-solid lithium-ion battery according to claim 1, characterized in that: The preparation method of the diaphragm comprises the following steps: Apply 2C+12+2LATP coating; The membrane is dried at a moderate temperature.

5. The semi-solid lithium-ion battery according to claim 1, characterized in that: The preparation method of the electrolyte comprises the following steps: preparing a high concentration electrolyte having a lithium salt concentration of 3.0 to 3.5 molar; The solvent composition is adjusted as needed to enhance the wettability and liquid absorption of the negative electrode.

6. The semi-solid lithium-ion battery according to claim 1, characterized in that: The positive electrode active material is selected from at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide.

7. The semi-solid lithium-ion battery according to claim 1, characterized in that: The solid electrolyte is Li1+xAlxTi2-x(PO4)3(LATP).

8. The semi-solid lithium-ion battery according to claim 1, characterized in that: The diaphragm is a polyolefin diaphragm, and both sides of the diaphragm are coated with a solid electrolyte coating.

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