Polymer electrolyte and high-conductivity particle co-coated high-nickel ternary positive electrode as well as preparation method and application of polymer electrolyte and high-conductivity particle co-coated high-nickel ternary positive electrode
By co-coating polymer electrolyte and highly conductive particles onto the surface of a high-nickel ternary cathode, the interfacial stability problem in all-solid-state batteries was solved, improving the cycle capacity and stability of the battery, reducing the internal resistance of the battery, and achieving higher electronic conductivity and ion permeation network.
Patent Information
- Application Number
- CN202511525225.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-24
- Publication Date
- 2026-02-13
AI Technical Summary
The interfacial stability issues between sulfide solid electrolytes and high-voltage cathode materials in all-solid-state batteries lead to battery capacity decay and short circuits. Existing inorganic coatings are brittle and have discontinuous electronic conduction paths, while polymer coatings have defects in the construction of electron transport networks in composite cathodes.
A high-nickel ternary cathode is co-coated with polymer electrolyte and highly conductive particles. Conductive particles are directionally loaded onto the surface of the high-nickel ternary cathode using radio frequency plasma technology, and a uniform polymer coating is formed on the surface by thermal polymerization, thereby improving electronic conductivity and interface stability.
It effectively avoids side reactions between the positive electrode and the sulfide electrolyte, improves the cycle capacity and stability of the all-solid-state battery, reduces the battery internal resistance, and enhances the electrochemical performance of the electron and ion permeation network.
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Figure CN121528877A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium ion batteries, in particular to a high-nickel ternary positive electrode coated with a polymer electrolyte and high-conductive particles, and a preparation method and application thereof. BACKGROUND
[0002] With the massive consumption of energy by human beings, environmental pollution and energy shortage crisis are becoming more and more serious, and the demand for clean and renewable energy is increasingly urgent in the world. In recent years, due to the development of electric vehicles and the increasing demand for large-scale energy storage in human life, research on lithium batteries has once again triggered a boom, and the development of secondary lithium batteries with higher safety, higher power, larger capacity and longer cycle life has become a new direction of lithium battery development. The safety hazards of traditional liquid lithium ion batteries have attracted widespread attention to solid-state batteries. Organic liquid batteries have a series of hidden dangers such as easy leakage, poor thermal stability, internal short circuit of the battery, and even fire and explosion. Solid-state batteries do not use flammable organic electrolyte, and the solid-state electrolyte also has no flowability and volatility, which can avoid the above safety problems.
[0003] However, full-solid-state batteries face some problems in application, mainly in the interface stability of sulfide solid-state electrolyte and positive electrode (mainly high-voltage positive electrode material). The sulfide electrolyte is thermodynamically unstable, and when it is in contact with the high-voltage positive electrode material, the electrolyte is prone to irreversible decomposition, generating elemental sulfur or lithium sulfide ion-conductive inert products, increasing the battery impedance, and causing the battery capacity to decay or even short circuit.
[0004] The current traditional coating layer, such as metal oxide (Al2O3, ZrO2), phosphate, etc. inorganic coating layer, etc. Such coating is a lithium ion insulator, with high interface impedance. And the inorganic coating layer has high brittleness, and the volume change caused by the positive electrode during charging and discharging can easily cause the coating layer to crack and lose its protective effect. Compared with inorganic coating layers, polymer coatings have certain lithium ion conductivity and good mechanical stability, and can effectively prevent excessive volume expansion of the positive electrode during charging and discharging cycles. However, when the polymer-coated positive electrode material is integrated into a composite positive electrode (i.e. a multi-component system containing active material, conductive agent, electrolyte, etc.), it often faces the problem of discontinuous or insufficient electronic conduction path, leading to increased battery resistance and limited rate performance. The core of this problem lies in the defect of the construction of the internal electronic transmission network of the composite positive electrode. SUMMARY
[0005] The present application aims to solve at least one of the above technical problems, and provides a high-nickel ternary positive electrode coated with a polymer electrolyte and a high-conductive particle, a preparation method and application thereof. The coated high-nickel ternary positive electrode can effectively avoid the problem of excessive side reaction with sulfide solid-state electrolyte in a full solid-state battery, and the high-conductive particle can effectively increase the conductivity of the composite positive electrode in the full solid-state battery.
[0006] In a first aspect, the present application provides a high-nickel ternary positive electrode coated with a polymer electrolyte and a high-conductive particle, wherein the polymer electrolyte comprises a polyacrylate electrolyte, and the high-conductive particle comprises a high-conductive oxide and / or a high-conductive nitride.
[0007] Preferably, the mass of the polymer electrolyte is 3-9 wt% of the high-nickel ternary positive electrode.
[0008] The mass of the high-conductive particle is 1-3 wt% of the high-nickel ternary positive electrode.
[0009] Preferably, the polyacrylate electrolyte comprises at least one of polyethylene glycol diacrylate, polymethyl methacrylate, and polyacrylic acid ethyl ester.
[0010] The high-conductive oxide comprises at least one of Ti2O3, RuO2, and indium tin oxide.
[0011] The high-conductive nitride comprises at least one of TiN and TaN.
[0012] Preferably, the high-conductive particle is distributed in a dot shape on the surface of the high-nickel ternary positive electrode, and the polymer electrolyte is uniformly coated on the surface of the high-nickel ternary positive electrode with a thickness of 1-5 nm.
[0013] In a second aspect, the present application provides a preparation method of a high-nickel ternary positive electrode coated with a polymer electrolyte and a high-conductive particle, comprising the following steps:
[0014] 1) adding a first silane coupling agent and a second silane coupling agent into an ethanol / water mixed solvent, respectively, and hydrolyzing for a period of time;
[0015] 2) placing the high-nickel ternary positive electrode and the high-conductive particle into a radio frequency plasma instrument, respectively, for a period of time to introduce hydroxyl groups to the surface thereof;
[0016] 3) placing the high-nickel ternary positive electrode into the solution after hydrolysis of the first silane coupling agent in step 1), and heating and stirring for a period of time, then filtering, washing, and drying; placing the high-conductive particle into the solution after hydrolysis of the second silane coupling agent in step 1), and heating and stirring for a period of time, then filtering, washing, and drying;
[0017] 4) The high-nickel ternary positive electrode and the high-conductive particles treated in step 3) are added into an ethanol solution and heated and stirred for a period of time; then filtered and dried to obtain a powder;
[0018] 5) The polymer electrolyte monomer and the thermal initiator are placed in an ethanol solution and stirred for 0.5-2 h, and the powder in step 4) is added, and after stirring for 2-3 h, solid-liquid separation is performed to obtain a solid, which is dried to obtain a high-nickel ternary positive electrode coated with a polymer electrolyte and high-conductive particles.
[0019] The present application realizes the directional loading of high-conductive particles on the surface of a high-nickel ternary positive electrode by radio frequency plasma technology, and then uniformly and thinly coats the surface of the high-nickel ternary positive electrode with a polymer coating by thermal polymerization. This method effectively alleviates the serious interface problem between the positive electrode and the sulfide solid-state electrolyte in the all-solid-state battery, and simultaneously improves the electronic conductivity of the positive electrode.
[0020] Preferably, in step 1), the first silane coupling agent and the second silane coupling agent are silane coupling agents that can participate in nucleophilic addition. In the high-nickel ternary positive electrode coated with high-conductive particles, the silane coupling agent can be regarded as a bonding agent between the high-conductive particles and the high-nickel ternary positive electrode. The first silane coupling agent can be "attached" to the surface of the high-nickel ternary positive electrode by plasma radio frequency technology, and the conductive particles are the same. Then the conductive particles are coated on the surface of the high-nickel ternary positive electrode by addition or ring-opening between the silane coupling agents.
[0021] Preferably, in step 1), the volume ratio of water to ethanol in the ethanol / water mixed solvent is (2:98)-(15:85);
[0022] The mass fraction of the first silane coupling agent is 0.5-2 wt%;
[0023] The mass fraction of the second silane coupling agent is 0.5-2 wt%;
[0024] The first silane coupling agent includes at least one of KH570, KH560, MPTES, and KH590;
[0025] The second silane coupling agent includes at least one of KH570, KH560, MPTES, and KH590;
[0026] KH560 contains an epoxy group and can undergo ring-opening. KH570 contains a carbon-carbon double bond and can undergo an addition reaction. MPTES and KH590 contain -SH, and the nucleophilic reagent containing -SH can attack an electron-deficient carbon atom to undergo nucleophilic addition.
[0027] The temperature of the heating and hydrolysis is 50-80℃, and the time of the heating and hydrolysis is 0.5-3 h.
[0028] Preferably, in the step 2), the particle size of the high-conductivity particles is 50-100 nm; the time for the radio frequency plasma instrument treatment is 2-10 min.
[0029] Preferably, in the step 3),
[0030] The mass ratio of the high-nickel ternary positive electrode to the first silane coupling agent is 0.5-1.5:1.
[0031] The mass ratio of the high-conductivity particles to the second silane coupling agent is 0.5-1.5:1.
[0032] The temperature for the heating and stirring is 50-80℃, and the time for the heating and stirring is 1-3 h.
[0033] The solvent used for the cleaning is ethanol.
[0034] Preferably, in the step 4), the temperature for the heating and stirring is 60-80℃, and the time for the heating and stirring is 4-8 h.
[0035] Preferably, in the step 5),
[0036] The mass ratio of the polymer monomer to the initiator is 20-60:1.
[0037] The polymer monomer is the main solute, and the mass fraction of the ethanol solution is 10-15%.
[0038] The mass ratio of the polymer electrolyte monomer to the high-nickel ternary positive electrode is 5-15:1, and the final polymer electrolyte coating content is 3-9 wt% of the high-nickel ternary positive electrode.
[0039] The mass of the high-conductivity particles is 1-3% of the high-nickel ternary positive electrode.
[0040] The solid-liquid separation includes suction filtration or centrifugal separation.
[0041] In a third aspect of the present application, the polymer electrolyte and high-conductivity particle co-coated high-nickel ternary positive electrode is provided as an application of the positive electrode material in a lithium ion full solid-state battery.
[0042] In a fourth aspect of the present application, a full solid-state lithium ion battery is provided, which includes a positive electrode, a negative electrode, and a solid-state electrolyte.
[0043] Preferably, the positive electrode includes the polymer electrolyte and high-conductivity particle co-coated high-nickel ternary positive electrode described in any one of the above, and the electrolyte is Li6PS5Cl or Li 10 GeP2S 12 .
[0044] Preferably, the positive electrode is a composite positive electrode, comprising a positive electrode material, a main solid-state electrolyte and conductive carbon black. The mass ratio of the positive electrode material, the solid-state electrolyte and the conductive carbon black is preferably 70:30:2.
[0045] Preferably, the negative electrode is a lithium-indium negative electrode, and the mass ratio of metal lithium to metal indium is 3:(5-50).
[0046] Compared with the prior art, the present application has the following advantages:
[0047] (1) The polymer electrolyte is selected as the coating main coating layer, which effectively prevents the direct contact between the high-nickel ternary positive electrode and the sulfide electrolyte, greatly reduces the violent side reaction between the positive electrode and the sulfide, and significantly improves the cycle capacity and stability. As a polymer, it has a certain elasticity, which can effectively prevent the lattice slip of the high-nickel ternary positive electrode generated during the cycle process; and inhibits the release of lattice oxygen, which on the other hand inhibits one of the sources of side reactions between the positive electrode and the sulfide solid-state electrolyte.
[0048] (2) The radio frequency plasma technology is used to introduce hydroxyl groups on the surface of the high-nickel ternary positive electrode and the highly conductive particles to condense with the silane coupling agent. The SH and C=C of the silane coupling agent are subjected to nucleophilic addition to realize the directional loading of the ternary positive electrode and the conductive particles, so as to ensure the strength and uniformity of the conductive particle coating. This method has a certain universality.
[0049] (3) The polymer electrolyte and the conductive particle are selected as the two-component coating layer, which provides an effective electronic and ionic permeation network for the composite positive electrode in the all-solid-state battery, and improves the electrochemical performance of the solid-state battery. BRIEF DESCRIPTION OF DRAWINGS
[0050] Figure 1 SEM image of the PEGDA and Ti2O3 co-coating in Example 2;
[0051] Figure 2 TEM image of the PEGDA and Ti2O3 co-coating in Example 2;
[0052] Figure 3 Cycle performance graph of the solid-state lithium ion battery assembled using the positive electrode of Example 2 and Comparative Example 1, respectively;
[0053] Figure 4 Impedance graph of the solid-state lithium ion battery assembled using the positive electrode of Example 2 and Comparative Example 1, respectively. DETAILED DESCRIPTION
[0054] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.
[0055] The instruments and reagents used in the present application are commercially available.
[0056] The conductive particles used in the preferred embodiments of the present application are commercially available conductive particles. After high-energy ball milling (700 r; ball-to-material ratio 60:1) of the commercially available conductive particles, small-particle-size (50-100 nm) conductive particles are obtained. The ratio of water to ethanol in the water / ethanol mixed solvent is a volume ratio.
[0057] Embodiment 1
[0058] (1) 200 mg of silane coupling agent KH570 is placed in 50 ml of a solvent with a water:ethanol ratio of 5:95, and hydrolysis is performed at 60°C for 1 h; 40 mg of silane coupling agent MPTES is placed in 10 ml of a solvent with a water:ethanol ratio of 5:95, and hydrolysis is performed at 60°C for 1 h.
[0059] (2) 400 mg of high-nickel ternary positive electrodes and 50 mg of high-conductive particles RuO2 are placed in a radio frequency plasma instrument respectively for 5 min to introduce hydroxyl groups to the surfaces thereof.
[0060] (3) 400 mg of high-nickel ternary positive electrodes are placed in the solution after hydrolysis of the silane coupling agent KH570 in (1), and 50 mg of high-conductive particles RuO2 are placed in the solution after hydrolysis of the silane coupling agent MPTES in (1), and stirring is performed at 60°C for 2 h, followed by filtration, washing with ethanol, and drying.
[0061] (4) 200 mg of the high-nickel ternary positive electrodes and high-conductive particles RuO2 in (3) are added to 20 ml of an ethanol solution, and stirring is performed at 60°C for 6 h, followed by filtration and drying.
[0062] (5) 500 mg of PMMA and 12.5 mg of thermal initiator AIBN are placed in 5 ml of an ethanol solution, and stirring is performed for 0.5 h, 100 mg of the powder in (4) is added, and stirring is performed for 2 h, followed by suction filtration and vacuum drying, to obtain high-nickel ternary positive electrodes coated with a polymer electrolyte and high-conductive particles.
[0063] The high-nickel ternary positive electrodes coated with a polymer electrolyte and high-conductive particles obtained in this embodiment have high-conductive particles uniformly distributed in the form of dots on the surface of the high-nickel ternary positive electrodes and oriented on the surface of the high-nickel ternary positive electrodes, and the polymer electrolyte has a coating with a thickness of about 2.5 nm on the surface of the high-nickel ternary positive electrodes.
[0064] Example 2
[0065] (1) 400 mg of silane coupling agent KH570 was placed in 50 ml of a solvent of water: ethanol = 5:95 and hydrolyzed at 60°C for 1 h; 50 mg of silane coupling agent MPTES was placed in 10 ml of a solvent of water: ethanol = 5:95 and hydrolyzed at 60°C for 1 h.
[0066] (2) 400 mg of high-nickel ternary positive electrode and 50 mg of high-conductive particle Ti2O3 were respectively placed in a radio frequency plasma instrument and treated for 5 min to introduce hydroxyl groups to the surface thereof.
[0067] (3) 400 mg of high-nickel ternary positive electrode was placed in the solution after hydrolysis of the silane coupling agent KH570 in (1), and 50 mg of high-conductive particle Ti2O3 was placed in the solution after hydrolysis of the silane coupling agent MPTES in (1), and heated and stirred at 60°C for 2 h, and then filtered, washed with ethanol, and dried.
[0068] (4) 200 mg of the high-nickel ternary positive electrode and high-conductive particle Ti2O3 in (3) was added to 20 ml of an ethanol solution and heated and stirred at 60°C for 6 h, and then filtered and dried.
[0069] (5) 500 mg of PEGDA and 12.5 mg of thermal initiator AIBN were placed in 5 ml of an ethanol solution and stirred for 0.5 h, 100 mg of the powder in (4) was added, and stirred for 2 h, and then suction filtered and vacuum dried to obtain a high-nickel ternary positive electrode coated with a polymer electrolyte and a high-conductive particle.
[0070] The high-nickel ternary positive electrode coated with a polymer electrolyte and a high-conductive particle obtained in the present example has the high-conductive particle uniformly distributed in a dot shape on the surface of the high-nickel ternary positive electrode and directionally loaded on the surface of the high-nickel ternary positive electrode, and the polymer electrolyte has a coating layer with a thickness of about 3 nm on the surface of the high-nickel ternary positive electrode.
[0071] Example 3
[0072] (1) 400 mg of silane coupling agent KH570 was placed in 50 ml of a solvent of water: ethanol = 5:95 and hydrolyzed at 60°C for 1 h; 50 mg of silane coupling agent MPTES was placed in 10 ml of a solvent of water: ethanol = 5:95 and hydrolyzed at 60°C for 1 h.
[0073] (2) 400 mg of high-nickel ternary positive electrode and 50 mg of high-conductive particle TiN were respectively placed in a radio frequency plasma instrument and treated for 5 min to introduce hydroxyl groups to the surface thereof.
[0074] (3) 400 mg high-nickel ternary positive electrode was placed in the solution after hydrolysis of silane coupling agent KH570 in (1), and 50 mg high-conductive particle TiN was placed in the solution after hydrolysis of silane coupling agent MPTES in (1), heated and stirred at 60°C for 2 h, filtered, washed with ethanol and dried.
[0075] (4) 200 mg of 6 mg high-nickel ternary positive electrode and high-conductive particle TiN in (3) were added to 20 ml of ethanol solution, heated and stirred at 70°C for 7 h, filtered and dried.
[0076] (5) 1000 mg PEGDA and 25 mg thermal initiator AIBN were placed in 5 ml of ethanol solution, stirred for 1 h, 100 mg of powder in (4) was added, stirred for 3 h, then suction filtered, vacuum dried, to obtain a high-nickel ternary positive electrode coated with polymer electrolyte and high-conductive particles.
[0077] The high-nickel ternary positive electrode coated with polymer electrolyte and high-conductive particles obtained in this example has high-conductive particles uniformly distributed in the form of dots on the surface of the high-nickel ternary positive electrode and oriented loaded on the surface of the high-nickel ternary positive electrode, and the polymer electrolyte has a coating with a thickness of about 3.5 nm on the surface of the high-nickel ternary positive electrode.
[0078] Example 4
[0079] (1) 400 mg of silane coupling agent KH570 was placed in 50 ml of a solvent of water: ethanol = 5:95, heated and hydrolyzed at 60°C for 1 h; 50 mg of silane coupling agent MPTES was placed in 10 ml of a solvent of water: ethanol = 5:95, heated and hydrolyzed at 60°C for 1 h.
[0080] (2) 400 mg of high-nickel ternary positive electrode and 50 mg of high-conductive particle ITO were respectively placed in a radio frequency plasma instrument for 5 min to introduce hydroxyl groups to the surface thereof.
[0081] (3) 400 mg high-nickel ternary positive electrode was placed in the solution after hydrolysis of silane coupling agent KH570 in (1), and 50 mg high-conductive particle ITO was placed in the solution after hydrolysis of silane coupling agent MPTES in (1), heated and stirred at 60°C for 2 h, filtered, washed with ethanol and dried.
[0082] (4) 200 mg of 6 mg high-nickel ternary positive electrode and high-conductive particle ITO in (3) were added to 20 ml of ethanol solution, heated and stirred at 70°C for 7 h, filtered and dried.
[0083] (5) 1000 mg PAE and 25 mg thermal initiator AIBN were placed in 5 ml of ethanol solution, stirred for 1 h, 100 mg of powder in (4) was added, stirred for 3 h, then suction filtered, vacuum dried, to obtain a high-nickel ternary positive electrode coated with polymer electrolyte and high-conductive particles.
[0084] The polymer electrolyte and high-conductive particle co-coated high-nickel ternary cathode obtained in this embodiment has high-conductive particles uniformly distributed in the form of dots on the surface of the high-nickel ternary cathode and oriented loaded on the surface of the high-nickel ternary cathode, and a polymer electrolyte with a coating layer of about 2 nm in thickness on the surface of the high-nickel ternary cathode.
[0085] Example 5
[0086] (1) 600 mg of silane coupling agent KH570 was placed in 50 ml of a solvent of water: ethanol = 5:95 and hydrolyzed at 60°C for 1 h; 70 mg of silane coupling agent KH590 was placed in 10 ml of a solvent of water: ethanol = 10:90 and hydrolyzed at 60°C for 1 h.
[0087] (2) 400 mg of high-nickel ternary cathode and 50 mg of high-conductive particle ITO were respectively placed in a radio frequency plasma instrument for 5 min to introduce hydroxyl groups to the surfaces thereof.
[0088] (3) 400 mg of high-nickel ternary cathode was placed in the solution after hydrolysis of the silane coupling agent KH570 in (1), and 50 mg of high-conductive particle ITO was placed in the solution after hydrolysis of the silane coupling agent KH590 in (1), and heated and stirred at 60°C for 2 h, and then filtered, washed with ethanol and dried.
[0089] (4) 200 mg of the high-nickel ternary cathode and high-conductive particle ITO in (3) were added to 20 ml of an ethanol solution and heated and stirred at 70°C for 7 h, and then filtered and dried.
[0090] (5) 1500 mg of PAE and 37.5 mg of thermal initiator AIBN were placed in 5 ml of an ethanol solution and stirred for 1 h, 100 mg of the powder in (4) was added, and stirred for 3 h, and then suction filtered and vacuum dried to obtain a polymer electrolyte and high-conductive particle co-coated high-nickel ternary cathode.
[0091] The polymer electrolyte and high-conductive particle co-coated high-nickel ternary cathode obtained in this embodiment has high-conductive particles uniformly distributed in the form of dots on the surface of the high-nickel ternary cathode and oriented loaded on the surface of the high-nickel ternary cathode, and a polymer electrolyte with a coating layer of about 4 nm in thickness on the surface of the high-nickel ternary cathode.
[0092] Example 6
[0093] (1) 800 mg of silane coupling agent KH560 was placed in 50 ml of a solvent of water: ethanol = 5:95 and hydrolyzed at 60°C for 1 h; 160 mg of silane coupling agent MPTES was placed in 10 ml of a solvent of water: ethanol = 10:90 and hydrolyzed at 60°C for 1 h.
[0094] (2) 400 mg high nickel ternary cathode and 50 mg high conductive particle TaN were placed in the radio frequency plasma instrument respectively for 5 min to introduce hydroxyl groups to the surface thereof.
[0095] (3) 400 mg high nickel ternary cathode was placed in the solution after hydrolysis of silane coupling agent KH560 in (1), and 50 mg high conductive particle TaN was placed in the solution after hydrolysis of silane coupling agent MPTES in (1), and heated and stirred at 60°C for 2 h, and then filtered, washed with ethanol and dried.
[0096] (4) 200 mg high nickel ternary cathode and high conductive particle ITO in (3) were added to 20 ml ethanol solution, heated and stirred at 70°C for 7 h, and then filtered and dried.
[0097] (5) 2000 mg PEGDA and 50 mg thermal initiator AIBN were placed in 5 ml ethanol solution, stirred for 1 h, and 100 mg powder in (4) was added, stirred for 3 h, and then suction filtered and vacuum dried to obtain a high nickel ternary cathode coated with polymer electrolyte and high conductive particle.
[0098] The high nickel ternary cathode coated with polymer electrolyte and high conductive particle obtained in the example has high conductive particles uniformly distributed in the form of dots on the surface of the high nickel ternary cathode and oriented loaded on the surface of the high nickel ternary cathode, and the polymer electrolyte has a coating with a thickness of about 5 nm on the surface of the high nickel ternary cathode.
[0099] Comparative Example 1
[0100] Comparative Example 1 is a commercial high nickel ternary cathode Li1N i0.8 Co 0.1 Mn 0.1 O2 (commercial 811 cathode).
[0101] Comparative Example 2
[0102] Comparative Example 2 is a high nickel ternary cathode Li1N i0.8 Co 0.1 Mn 0.1 O2 coated only with polymer electrolyte. The specific implementation steps are as follows:
[0103] (1) 100 mg high nickel ternary cathode was placed in the radio frequency plasma instrument for 5 min to introduce hydroxyl groups to the surface thereof.
[0104] (2) 500 mg PEGDA and 12.5 mg thermal initiator AIBN were placed in ethanol solution and stirred for 0.5 h, and 100 mg powder in (1) was added, stirred for 2 h, and then suction filtered and vacuum dried to obtain a high nickel ternary cathode coated with polymer electrolyte.
[0105] Comparative Example 3 is replaced with a silane coupling agent that cannot participate in nucleophilic addition
[0106] Figure 1 a, b are SEM images of high-nickel ternary cathodes prepared in Example 2, and it can be seen that Ti2O3 is uniformly distributed in the form of dots on the surface of the high-nickel ternary cathode.
[0107] Figure 2 a, b are TEM images of high-nickel ternary cathodes prepared in Example 2, and it can be seen that Ti2O3 is directionally loaded on the surface of the high-nickel ternary cathode at high magnification, and the thickness of the polymer PEGDA coating is about 3 nm.
[0108] The high-nickel ternary cathodes obtained in Examples 1-6 and Comparative Examples 1 and 2 were assembled into full solid-state lithium ion batteries. The assembly method is as follows: first, take the high-nickel ternary cathode, Li6PS5Cl, and conductive carbon black in the mass ratio of 70:30:2, add them to a mortar and grind for 20 min to obtain a composite cathode.
[0109] First, 60 mg of Li6PS5Cl2 electrolyte powder was placed in a polyether ether ketone mold with a diameter of 10 mm, and a pressure of 1.5 t was applied for 5 s. Then 7 mg of the composite cathode was placed on one side of the Li6PS5Cl powder, and a pressure of 3 t was applied for 5 min. Finally, a metal In sheet and a Li sheet were placed on the other side of the Li6PS5Cl, and the mold was assembled under pressure to obtain a full solid-state lithium ion battery. The solid-state battery assembly process was completed in an Ar atmosphere glove box. The charge and discharge voltage range was set to 1.9 V-3.8 V, and the assembled solid-state lithium ion battery was tested for constant current charge and discharge and impedance.
[0110] Table 1
[0111] Cycle performance (0.5C 50 cycles) Impedance Example 1 121 mA h g -1 ]] 334 Ω Example 2 165 mA h g -1 ]] 151 Ω Example 3 132 mA h g -1 ]] 235 Ω Example 4 135 mA h g -1 ]] 312 Ω Example 5 127 mA h g -1 ]] 407 Ω Example 6 120 mA h g -1 ]] 610 Ω Comparative Example 1 115 mA h g -1 ]] 857 Ω Comparative Example 2 117 mA h g -1 ]] 646 Ω
[0112] The electrochemical performance of the obtained full solid-state lithium ion battery was tested, and the cycle performance results of the full solid-state lithium ion battery are shown in Figure 3 The full cell voltage range is between 1.9 V and 3.8 V, and a current of 0.5 C is used. As can be seen from Figure 3 , the cycle performance of the high-nickel ternary cathode after coating shows a significant improvement: the battery coated in Example 2 still has a capacity of 165 mAh g -1 after 50 cycles, while the battery of the commercial 811 cathode without coating in Comparative Example 1 has a capacity of only 115 mA hg -1And, the comparative example 1, the uncoated commercial 811 positive electrode, has a significant impedance increase phenomenon compared to the high-nickel ternary positive electrode after polymer coating, which is 857 Ω; the impedance of the co-coating in example 2 is smaller, which is 151 Ω. The present application selects a polymer electrolyte and a conductive particle as a two-component coating layer, which provides an effective electronic and ionic permeation network for the composite positive electrode in the all-solid-state battery, and improves the electrochemical performance of the solid-state battery.
[0113] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for limiting the present application, although the foregoing embodiments of the present application are described in detail, for those skilled in the art, it still can be modified, or part of the technical features of the equivalent replacement, within the spirit and principles of the present application, any modification, equivalent replacement, improvement, etc., should be included in the scope of protection of the present application.
Claims
1. A high-nickel ternary cathode co-coated with a polymer electrolyte and highly conductive particles, characterized in that, The polymer electrolyte includes polyacrylate electrolytes, and the highly conductive particles include highly conductive oxides and / or highly conductive nitrides.
2. The high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles according to claim 1, characterized in that, The polymer electrolyte comprises 3–9 wt% of the high-nickel ternary cathode. The mass of the highly conductive particles is 1 to 3 wt% of the high-nickel ternary cathode. The polyacrylate electrolyte includes at least one of polyethylene glycol diacrylate, polymethyl methacrylate, and ethyl polyacrylate. The highly conductive oxide includes at least one of Ti2O3, RuO2, and indium tin oxide; At least one of the highly conductive nitrides TiN and TaN.
3. The high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles according to claim 1, characterized in that, The highly conductive particles are distributed in a dotted pattern on the surface of the high-nickel ternary cathode. The polymer electrolyte forms a uniform coating with a thickness of 1–5 nm on the surface of the high-nickel ternary cathode.
4. A method for preparing a high-nickel ternary cathode co-coated with a polymer electrolyte and highly conductive particles, characterized in that, Includes the following steps: 1) Add the first silane coupling agent and the second silane coupling agent to a mixed solvent of ethanol / water, and heat to hydrolyze for a period of time; 2) The high-nickel ternary cathode and the high-conductivity particles were respectively placed in a radio frequency plasma instrument for a period of time to introduce hydroxyl groups to their surface; 3) Place the high-nickel ternary cathode in the solution after hydrolysis of the first silane coupling agent in step 1), heat and stir for a period of time, then filter, wash and dry; place the high-conductivity particles in the solution after hydrolysis of the second silane coupling agent in step 1), heat and stir for a period of time, then filter, wash and dry. 4) Add the high-nickel ternary cathode and highly conductive particles treated in step 3) into an ethanol solution and heat and stir for a period of time. Then filter and dry to obtain powder; 5) Place the polymer electrolyte monomer and thermal initiator in an ethanol solution and stir for 0.5 to 2 hours. Add the powder obtained in step 4) and stir for 2 to 3 hours. Separate the solid and liquid to obtain a solid. Dry the solid to obtain a high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles.
5. The method for preparing a high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles according to claim 4, characterized in that, In step 1), the volume ratio of water to ethanol in the water / ethanol mixed solvent is (2:98) to (15:85). The mass fraction of the first silane coupling agent solution is 0.5–2 wt%. The mass fraction of the second silane coupling agent solution is 0.5–2 wt%. The first silane coupling agent includes at least one of KH570, KH560, MPTES, and KH590; The first silane coupling agent includes at least one of KH570, KH560, MPTES, and KH590; The temperature for hydrolysis is 50–80℃, and the hydrolysis time is 0.5–3 hours.
6. The method for preparing a high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles according to claim 4, characterized in that, In step 2), the particle size of the highly conductive particles is 50–100 nm; the treatment time of the radio frequency plasma instrument is 2–10 min.
7. The method for preparing a high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles according to claim 4, characterized in that, In step 3), The mass ratio of the high-nickel ternary cathode to the first silane coupling agent is 0.5–1.5:1; The mass ratio of highly conductive particles to the second silane coupling agent is 0.5–1.5:
1. The heating and stirring temperature is 50–80℃, and the heating and stirring time is 1–3 hours; The solvent used for cleaning is ethanol.
8. The method for preparing a high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles according to claim 4, characterized in that, In step 4), the heating and stirring temperature is 60-80℃, and the heating and stirring time is 4-8h.
9. The method for preparing a high-nickel ternary cathode co-coated with polymer electrolyte and highly conductive particles according to claim 4, characterized in that, In step 5), The mass ratio of polymer monomer to initiator is 20–60:1; The polymer monomer is the main solute, and the mass fraction of this ethanol solution is 10-15%. The mass ratio of polymer electrolyte monomer to high-nickel ternary cathode is 5-15:1, and the final polymer electrolyte coating content is 3-9 wt% of the high-nickel ternary cathode. The mass of highly conductive particles is 1-3% of that of high-nickel ternary cathodes; Solid-liquid separation includes vacuum filtration or centrifugation.
10. The application of a high-nickel ternary cathode co-coated with a polymer electrolyte and highly conductive particles according to any one of claims 1 to 9 as a cathode material in a lithium-ion all-solid-state battery.