A flexible composite electrolyte, a solid-state magnesium-aluminum battery and its preparation method

Abstract

This invention discloses a flexible composite electrolyte, a solid-state magnesium-aluminum battery, and a method for preparing the same. The flexible composite electrolyte comprises the following components by mass percentage: 50-70 wt% polyquaternium-51, 20-40 wt% plasticizer, 5-10 wt% LLZO nanowires, and 2-5 wt% PZT particles. This invention utilizes a flexible composite electrode made from polyquaternium-51, plasticizer, ionic liquid, LLZO nanowires, and PZT particles in a specific ratio, along with a Mg-Al alloy anode and an NMC811@LiNbO3 cathode, to form a solid-state magnesium-aluminum battery with a "composite electrolyte + nickel-based cathode + magnesium-aluminum anode" configuration. This battery exhibits high conductivity, high stability, and long lifespan.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a flexible composite electrolyte, a solid magnesium-aluminum battery, and a method for preparing the same. Background Technology

[0002] With the development of renewable energy, the demand for energy storage technologies with long lifespan, high conductivity, high safety, and low cost is becoming increasingly urgent. Aluminum batteries have attracted much attention due to their abundant raw materials, high safety, and high theoretical specific capacity. However, existing solid-state batteries cannot simultaneously meet the requirements of high conductivity, high safety, and long lifespan, specifically because polymer electrolytes (such as PEO) have poor room temperature conductivity (<10). -4 S / cm); Lithium metal anodes have a high risk of dendrite puncture (see...). Figure 1 High-nickel cathodes pose a significant risk of thermal runaway; numerous side reactions occur at the interface, leading to a surge in impedance. Therefore, developing a solid-state battery that simultaneously satisfies high conductivity, high safety, and long lifespan is a pressing technical challenge. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a flexible composite electrolyte that solves the problem that existing solid-state batteries cannot simultaneously meet the requirements of high conductivity, high safety, and long life.

[0004] The present invention also aims to provide a method for preparing a solid magnesium-aluminum battery, a flexible composite electrolyte, and a method for preparing a solid magnesium-aluminum battery.

[0005] To achieve the above objectives, the first technical solution of the present invention is as follows: a flexible composite electrolyte comprising the following components by mass percentage: polyquaternium-51 50~70 wt%, plasticizer 20~40 wt%, LLZO nanowires 5~10 wt%, and PZT particles 2~5 wt%.

[0006] Preferably, the plasticizer is a 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid.

[0007] Another technical solution of the present invention is implemented as follows: a solid magnesium-aluminum battery, comprising a positive electrode, a negative electrode and the flexible composite electrolyte as described in claim 1; the positive electrode is an NMC811 positive electrode material with 1~3 nm LiNbO3 coated on its surface; the negative electrode is a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:(4~6).

[0008] The third technical solution of the present invention is achieved as follows: the preparation method of the above-mentioned flexible composite electrolyte specifically includes the following steps: S1. Prepare raw materials: Weigh out the following by mass percentage: 50~70 wt% of polyquaternium-51, 20~40 wt% of plasticizer, 5~10 wt% of LLZO nanowires and 2~5 wt% of PZT particles; S2. Pre-prepared slurry: The LLZO nanowires and PZT particles are dissolved in an organic solvent to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the plasticizer to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment to obtain a flexible composite electrolyte.

[0009] Preferably, in step S1, the plasticizer is a 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid.

[0010] Preferably, in step S7, the sintering temperature is 800°C to 1200°C, and the sintering holding time is 2 h to 8 h.

[0011] The fourth technical solution of the present invention is achieved as follows: the preparation method of the above-mentioned solid magnesium-aluminum battery includes the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After being left to stand and age, a solid magnesium-aluminum battery is obtained.

[0012] Preferably, the preparation of the positive electrode specifically includes: A 1-3 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material, and the cathode was obtained after drying.

[0013] Preferably, the flexible composite electrolyte is pretreated, specifically including: The flexible composite electrolyte is heat-treated at 60℃ to 80℃ to maintain its water content at 3% to 5%.

[0014] Preferably, the negative electrode undergoes pretreatment, specifically including: The negative electrode is subjected to plasma cleaning to activate its surface, and the surface-activated negative electrode is then modified.

[0015] Compared with existing technologies, this invention utilizes a flexible composite electrolyte made from polyquaternary ammonium salt-51, a plasticizer ionic liquid, LLZO nanowires, and PZT particles in a specific ratio, along with a Mg-Al alloy anode and an NMC811@LiNbO3 cathode, to form a solid-state magnesium-aluminum battery with a "composite electrolyte + nickel-based cathode + magnesium-aluminum anode" configuration. This battery exhibits high conductivity, high stability, and long lifespan. Specifically: 1) The flexible composite electrolyte in this battery has an ionic conductivity as high as 2.1 × 10⁻⁶. -3 1) The S / cm is 100 times higher than that of existing pure polymer batteries; 2) The negative electrode stability of this battery is <50 mV, and the negative electrode material is dendrite-free, ensuring high safety and thus guaranteeing the long-term storage and use safety of the battery; 3) The interface impedance of the NMC811@LiNbO3 positive electrode material in this battery is reduced to 68 Ω·cm. 2 4) The battery has a cycle life of up to 91% and an extremely low rate of degradation; 5) The battery has a rate performance of up to 153 mAh / g, which meets the requirements of fast charging.

[0016] This invention obtains the battery by employing a fabrication process that combines film casting with hot pressing and stacking, laying a solid foundation for obtaining high-performance batteries. Attached Figure Description

[0017] Figure 1 This is a scanning electron microscope image of an existing negative electrode material; Figure 2 This is a scanning electron microscope image of the negative electrode material of this invention application; Figure 3 The time-voltage & current graph of the solid magnesium-aluminum battery prepared in Example 1 of this application during charge-discharge cycle testing; Figure 4 This is a capacity-voltage diagram of the solid magnesium-aluminum battery prepared in Example 1 of this application during charge-discharge cycle testing; Figure 5 This is a schematic diagram showing the distribution of the negative electrode magnesium-aluminum alloy composite material, the electrolyte material, and the positive electrode nickel-based composite material prepared in Example 1 of the present invention. Figure 6 This is a physical image of the solid magnesium-aluminum battery prepared in Example 1 of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In the description of this invention, it should be clarified that the terms "vertical," "lateral," "longitudinal," "front," "rear," "left," "right," "up," "down," and "horizontal," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are merely for the convenience of describing this invention. They do not imply that the device or element referred to must have a specific orientation or position, and therefore should not be construed as a limitation of this invention. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," and "joined" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] The present invention provides a flexible composite electrolyte comprising the following components by mass percentage: 50-70 wt% polyquaternium-51, 20-40 wt% plasticizer, 5-10 wt% LLZO nanowires, and 2-5 wt% PZT particles; wherein the plasticizer is a 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid.

[0021] This invention also provides a solid magnesium-aluminum battery, comprising a positive electrode, a negative electrode, and the flexible composite electrolyte as described in claim 1; the positive electrode is selected from NMC811 positive electrode material with a surface coating of 1~3 nm LiNbO3; the negative electrode is selected from a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:(4~6).

[0022] This invention also provides a method for preparing a flexible composite electrolyte, which specifically includes the following steps: S1. Prepare raw materials: Weigh out the following by mass percentage: 50-70 wt% of polyquaternium-51, 20-40 wt% of plasticizer, 5-10 wt% of LLZO nanowires, and 2-5 wt% of PZT particles; the plasticizer is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid; S2. Pre-prepared slurry: The LLZO nanowires and PZT particles are dissolved in an organic solvent to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the plasticizer to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment, the sintering temperature is 800~1200°C, and the sintering holding time is 2~8h to obtain a flexible composite electrolyte.

[0023] This invention also provides a method for preparing a solid-state magnesium-aluminum battery, characterized by comprising the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After being left to stand and age, a solid magnesium-aluminum battery is obtained.

[0024] In the specific implementation process, the preparation of the positive electrode includes: A 1-3 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material, and the cathode was obtained after drying.

[0025] The flexible composite electrolyte is pretreated, specifically by heat-treating it at 60℃ to 80℃ to maintain its water content at 3% to 5%.

[0026] The negative electrode is pretreated, specifically including: plasma cleaning of the negative electrode to activate its surface, and modification of the surface-activated negative electrode.

[0027] The following are specific examples. Example 1

[0028] The flexible composite electrolyte provided in Example 1 of this invention comprises the following components by mass percentage: 60 wt% polyquaternium salt-51, 30 wt% 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 8 wt% LLZO nanowires, and 3 wt% PZT particles.

[0029] The solid magnesium-aluminum battery provided in Embodiment 1 of the present invention includes a positive electrode, a negative electrode, and the flexible composite electrolyte as described in claim 1; the positive electrode is an NMC811 positive electrode material with 2nm LiNbO3 coated on its surface; the negative electrode is a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:5.

[0030] The preparation method of the flexible composite electrolyte provided in Embodiment 1 of the present invention specifically includes the following steps: S1. Prepare raw materials: Weigh the following by mass percentage: 60 wt% of polyquaternium-51, 30 wt% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 8 wt% of LLZO nanowires and 3 wt% of PZT particles. S2. Pre-prepared slurry: Dissolve the LLZO nanowires and the PZT particles in a mixed solvent of 500g of ethanol and toluene to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment, the sintering temperature is 1000°C, and the sintering holding time is 5h to obtain a flexible composite electrolyte.

[0031] The method for preparing a solid-state magnesium-aluminum battery provided in Embodiment 1 of the present invention includes the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After standing and aging, a solid-state magnesium-aluminum battery is obtained. See details. Figure 6 A picture of the actual product.

[0032] The preparation of the positive electrode specifically includes: A 2 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material, and the cathode was obtained after drying.

[0033] The pretreatment of the flexible composite electrolyte specifically includes: heat-treating the flexible composite electrolyte at 70°C to maintain its water content at 4%; the pretreatment of the negative electrode specifically includes: plasma cleaning of the negative electrode to activate its surface, and modifying the surface-activated negative electrode.

[0034] Example 2

[0035] The flexible composite electrolyte provided in Example 2 of this invention comprises the following components by mass percentage: 50 wt% polyquaternium salt-51, 20 wt% 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 5 wt% LLZO nanowires, and 2 wt% PZT particles.

[0036] The solid magnesium-aluminum battery provided in Embodiment 2 of the present invention includes a positive electrode, a negative electrode, and the flexible composite electrolyte as described in claim 1; the positive electrode is an NMC811 positive electrode material with 1 nm LiNbO3 coated on its surface; the negative electrode is a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:4.

[0037] The preparation method of the flexible composite electrolyte provided in Embodiment 2 of the present invention specifically includes the following steps: S1. Prepare raw materials: Weigh out the following by mass percentage: 50 wt% of polyquaternary ammonium salt-51, 20 wt% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 5 wt% of LLZO nanowires and 2 wt% of PZT particles. S2. Pre-prepared slurry: Dissolve the LLZO nanowires and the PZT particles in a mixed solvent of 500g of ethanol and toluene to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment, the sintering temperature is 800°C, and the sintering holding time is 2h to obtain a flexible composite electrolyte.

[0038] The method for preparing a solid-state magnesium-aluminum battery provided in Embodiment 2 of the present invention includes the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After being left to stand and age, a solid magnesium-aluminum battery is obtained.

[0039] The preparation of the positive electrode specifically includes: A 1 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material and dried to obtain the cathode.

[0040] The flexible composite electrolyte is pretreated by heat treatment at 60°C to maintain its water content at 3%. The negative electrode is pretreated by plasma cleaning to activate its surface and then modifying the activated negative electrode.

[0041] Example 3

[0042] The flexible composite electrolyte provided in Example 3 of this invention comprises the following components by mass percentage: 70 wt% polyquaternium-51, 40 wt% 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 10 wt% LLZO nanowires, and 5 wt% PZT particles.

[0043] The solid magnesium-aluminum battery provided in Embodiment 3 of the present invention includes a positive electrode, a negative electrode and the above-mentioned flexible composite electrolyte; the positive electrode is an NMC811 positive electrode material with 3 nm LiNbO3 coated on its surface; the negative electrode is a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:6.

[0044] The preparation method of the flexible composite electrolyte provided in Embodiment 3 of the present invention specifically includes the following steps: S1. Prepare raw materials: Weigh the following by mass percentage: 70 wt% of polyquaternium-51, 40 wt% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 10 wt% of LLZO nanowires and 5 wt% of PZT particles. S2. Pre-prepared slurry: Dissolve the LLZO nanowires and the PZT particles in a mixed solvent of 500g of ethanol and toluene to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment, the sintering temperature is 1200°C, and the sintering holding time is 8h to obtain a flexible composite electrolyte.

[0045] The method for preparing a solid-state magnesium-aluminum battery provided in Embodiment 3 of the present invention includes the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After being left to stand and age, a solid magnesium-aluminum battery is obtained.

[0046] The preparation of the positive electrode specifically includes: A 3 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material and dried to obtain the cathode.

[0047] The flexible composite electrolyte is pretreated by heat treatment at 80°C to maintain its water content at 5%. The negative electrode is pretreated by plasma cleaning to activate its surface and then modifying the activated negative electrode.

[0048] Example 4

[0049] The flexible composite electrolyte provided in Example 4 of this invention comprises the following components by mass percentage: 50 wt% polyquaternium salt-51, 40 wt% 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 5 wt% LLZO nanowires, and 5 wt% PZT particles.

[0050] The solid magnesium-aluminum battery provided in Embodiment 4 of the present invention includes a positive electrode, a negative electrode, and the flexible composite electrolyte as described in claim 1; the positive electrode is an NMC811 positive electrode material with 2 nm LiNbO3 coated on its surface; the negative electrode is a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:5.

[0051] The preparation method of the flexible composite electrolyte provided in Embodiment 4 of the present invention specifically includes the following steps: S1. Prepare raw materials: Weigh out the following by mass percentage: 50 wt% of polyquaternium-51, 40 wt% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 5 wt% of LLZO nanowires and 5 wt% of PZT particles. S2. Pre-prepared slurry: Dissolve the LLZO nanowires and the PZT particles in a mixed solvent of 500g of ethanol and toluene to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment, the sintering temperature is 800°C, and the sintering holding time is 8h to obtain a flexible composite electrolyte.

[0052] The method for preparing a solid-state magnesium-aluminum battery provided in Embodiment 4 of the present invention includes the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After being left to stand and age, a solid magnesium-aluminum battery is obtained.

[0053] The preparation of the positive electrode specifically includes: A 2 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material, and the cathode was obtained after drying.

[0054] The pretreatment of the flexible composite electrolyte specifically includes: heat-treating the flexible composite electrolyte at 70°C to maintain its water content at 4%; the pretreatment of the negative electrode specifically includes: plasma cleaning of the negative electrode to activate its surface, and modifying the surface-activated negative electrode.

[0055] Example 5

[0056] The flexible composite electrolyte provided in Example 5 of this invention comprises the following components by mass percentage: 70 wt% polyquaternium-51, 20 wt% 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 10 wt% LLZO nanowires, and 2 wt% PZT particles.

[0057] The solid magnesium-aluminum battery provided in Embodiment 5 of the present invention includes a positive electrode, a negative electrode, and the flexible composite electrolyte as described in claim 1; the positive electrode is an NMC811 positive electrode material with 2 nm LiNbO3 coated on its surface; the negative electrode is a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:5.

[0058] The method for preparing the flexible composite electrolyte described above in Embodiment 5 of the present invention specifically includes the following steps: S1. Prepare raw materials: Weigh the following by mass percentage: 70 wt% of polyquaternium-51, 20 wt% of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid, 10 wt% of LLZO nanowires and 2 wt% of PZT particles. S2. Pre-prepared slurry: Dissolve the LLZO nanowires and the PZT particles in a mixed solvent of 500g of ethanol and toluene to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment, the sintering temperature is 1200℃, and the sintering holding time is 2h to obtain a flexible composite electrolyte.

[0059] The method for preparing a solid-state magnesium-aluminum battery provided in Example 5 of this invention Includes the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After being left to stand and age, a solid magnesium-aluminum battery is obtained.

[0060] The preparation of the positive electrode specifically includes: A 2 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material, and the cathode was obtained after drying.

[0061] The pretreatment of the flexible composite electrolyte specifically includes: heat-treating the flexible composite electrolyte at 70°C to maintain its water content at 4%; the pretreatment of the negative electrode specifically includes: plasma cleaning of the negative electrode to activate its surface, and modifying the surface-activated negative electrode.

[0062] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the Comparative Example uses a conventional electrolyte (pure polymer), while the other process parameters are the same as those in Example 1.

[0063] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the comparative example uses NMC811 without LiNbO3 coating as the positive electrode, while the other process parameters are the same as those in Example 1. Performance testing

[0064] 1. The ionic conductivity of the flexible composite electrolyte of the present invention and the traditional pure polymer electrolyte were tested.

[0065] (1) Test equipment and methods: An electrochemical workstation was used, with stainless steel blocking electrodes used to clamp the flexible composite electrolyte obtained in Example 1 of this invention and the conventional pure polymer electrolyte described in the comparative example, respectively; the test temperature was 25℃, and the AC impedance scanning frequency range was 10. 6 From Hz to 0.01Hz, obtain the electrolyte bulk ionic impedance corresponding to the high-frequency real axis intercept. R ion ; Measuring electrolyte membrane thickness L Effective contact area of ​​electrodes S According to the formula for ionic conductivity σ ion = L / ( R ion · S Calculate the ionic conductivity.

[0066] (2) Test results: The ionic conductivity of the composite electrolyte of this invention is 2.1 × 10⁻⁶. -3 S / cm; the ionic conductivity of the comparative pure polymer electrolyte is 2.1 × 10⁻⁶. -5 Compared to S / cm, the ionic conductivity of the flexible composite electrolyte of this invention is increased by 100 times.

[0067] 2. Testing of the negative electrode stability in the solid-state magnesium-aluminum battery of this invention (interface stability of Mg-Al alloy negative electrode, verification of no dendrites) (1) Test method: Voltage polarization stability test: The solid battery obtained in Example 1 of this invention is used as the test object. Under constant temperature of 25℃, it is continuously charged and discharged for 100 h with a constant current of 0.1mA / cm². The steady-state polarization voltage fluctuation difference on the negative electrode side is recorded in real time to characterize the stability of the negative electrode interface. Dendrite morphology observation: After completing the long-term polarization test, the battery cell was disassembled in an argon-filled glove box. The negative electrode surface was cleaned with DMC solvent and vacuum dried. The microstructure of the Mg-Al alloy negative electrode surface was observed using a scanning electron microscope (SEM); see details below. Figure 2 , Figure 2 This is a scanning electron microscope image of the negative electrode material. Analysis... Figure 2 It is evident that the surface of the negative electrode material is dendrite-free, thus laying a solid foundation for the fabrication of high-performance batteries.

[0068] (2) Test results: The difference in the negative electrode polarization voltage fluctuation range was <50 mV throughout the test, and the interface polarization was stable. SEM observation showed that the negative electrode surface was flat and dense, with no magnesium metal dendrites, protrusions, or puncture-like morphology generated, effectively avoiding the risk of dendrite puncture short circuit and ensuring the safety of long-term storage and cyclic use of the battery.

[0069] 3. Detection of the positive electrode interface impedance in the solid magnesium-aluminum battery of this invention (interface performance of the positive electrode coated with NMC811@LiNbO3). (1) Test method: Using the solid-state battery obtained in Example 1 of this invention and the battery obtained in the comparative example as controls, EIS AC impedance test was carried out after standing at 25°C for 2 h, with a frequency range of 10. 6 ~0.01 Hz; high-frequency semicircle of fitted impedance spectrum, extracting charge transfer impedance at the cathode-electrolyte interface. R ct Unit conversion to area ratio impedance (Ω·cm) 2}).

[0070] (2) Test results: The interfacial impedance of the NMC811@LiNbO3 coated positive electrode of this invention is 68 Ω·cm. 2 Under the same conditions, the interfacial impedance of the uncoated NMC811 positive electrode is 309 Ω·cm. 2 After coating, the interfacial impedance decreased by 78%.

[0071] 4. Cycle life capacity retention test of the solid magnesium-aluminum battery of this invention (1) Test method: Taking the solid-state battery obtained in Example 1 of this invention as the standard, under the condition of 25°C, the constant charge and discharge rate of 0.5C is continuously cycled for 500 cycles according to the standard voltage window of solid magnesium-aluminum battery; the discharge capacity is recorded every 50 cycles, and the capacity retention rate is calculated after the cycle ends based on the discharge capacity of the first cycle.

[0072] (2) Test results: After 500 long cycles, the solid magnesium-aluminum battery of the present invention can retain up to 91% of its capacity, and the capacity decay rate during the cycle is extremely low, with an ultra-long service life.

[0073] 5) Performance test of the solid magnesium-aluminum battery of this invention at high rate (fast charging compatibility performance) (1) Test method: Taking the solid-state battery obtained in Example 1 of this invention as the standard, under constant temperature of 25℃, it was uniformly charged to full charge using a small current of 0.2C; and discharged to the cutoff voltage using constant current at rates of 0.1C, 0.5C, 1C and 2C respectively. The discharge specific capacity at each rate was recorded, and the discharge specific capacity at a high rate of 2C was selected as the fast charging performance evaluation index.

[0074] (2) Test results: The battery of the present invention has a 2C high-rate discharge specific capacity of up to 153 mAh / g. The capacity is excellent at high rates and can meet the needs of fast charging.

[0075] 6) The charging capacity, discharging capacity, coulombic efficiency, and median voltage of the solid magnesium-aluminum battery of the present invention were tested. (1) Test method: The batteries obtained in Examples 1-5, as well as the batteries obtained in Comparative Example 1 and Comparative Document 2, were tested using the Blue Battery Test System (BTSDA 7.6.0.425). The test conditions were set as follows: 10C constant current and constant voltage charging (cutoff current 0.02C), followed by 1C constant current discharge to the cutoff voltage.

[0076] (2) Test results: The charging time was about 18 minutes and the discharging time was about 30 minutes. Other test results are shown in Table 1.

[0077] Table 1 Performance test data of solid-state magnesium-aluminum batteries

[0078] Test results show that the charging time is approximately 18 minutes, the discharging time is approximately 30 minutes, and other test results are as follows: Figure 5 , Figure 6 As shown in Table 1, the test results show that the solid magnesium-aluminum battery provided in this embodiment has an ultra-long cycle life. After more than 15,000 charge-discharge cycles, the capacity retention rate is still close to 100%, and the charge-discharge efficiency is stable at more than 98.5%, which far exceeds the level of existing solid magnesium-aluminum batteries. The median voltage is around 1.65V, which significantly shortens the charging time.

[0079] Test results show that the charging time is approximately 18 minutes, the discharging time is approximately 30 minutes, and other test results are as follows: Figure 5 , Figure 6 As shown in Table 1, the test results show that the solid magnesium-aluminum battery provided in this embodiment has an ultra-long cycle life. After more than 15,000 charge-discharge cycles, the capacity retention rate is still close to 100%, and the charge-discharge efficiency is stable at more than 98.5%, which far exceeds the level of existing solid magnesium-aluminum batteries. The median voltage is around 1.65V, which significantly shortens the charging time.

[0080] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A flexible composite electrolyte, characterized in that, It includes the following components by weight percentage: polyquaternium-51 50~70wt%, plasticizer 20~40wt%, LLZO nanowires 5~10wt%, and PZT particles 2~5wt%.

2. The flexible composite electrolyte according to claim 1, characterized in that, The plasticizer is a 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid.

3. A solid-state magnesium-aluminum battery, characterized in that, The device includes a positive electrode, a negative electrode, and the flexible composite electrolyte as described in claim 1; the positive electrode is an NMC811 positive electrode material with a surface coating of 1~3 nm LiNbO3; the negative electrode is a magnesium-aluminum alloy, wherein the percentage of magnesium to aluminum in the magnesium-aluminum alloy is 1:(4~6).

4. A method for preparing the flexible composite electrolyte according to claim 1 or 2, characterized in that, The method specifically includes the following steps: S1. Prepare raw materials: Weigh out the following by mass percentage: 50-70 wt% polyquaternium-51, 20-40 wt% plasticizer, 5-10 wt% LLZO nanowires and 2-5 wt% PZT particles. S2. Pre-prepared slurry: The LLZO nanowires and PZT particles are dissolved in an organic solvent to form a homogeneous suspension slurry; S3. Slurry molding: Add the polyquaternary ammonium salt and the plasticizer to the suspension slurry and mix thoroughly again to form a homogeneous molding slurry; S4. Casting film: The molding slurry is cast into a single-layer electrolyte membrane blank; S5. Hybrid stacking: The single-layer electrolyte membrane preform is stacked; S6: Hot pressing: Hot pressing the laminated film preform; S7: Degreasing heat treatment: The multiphase green blank is subjected to degreasing heat treatment to form a green blank; the green blank is further placed in a high-temperature furnace for sintering heat treatment to obtain a flexible composite electrolyte.

5. The method for preparing the flexible composite electrolyte according to claim 4, characterized in that, In S1, the plasticizer is a 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid.

6. The method for preparing the flexible composite electrolyte according to claim 4 or 5, characterized in that, In step S7, the sintering temperature is 800°C to 1200°C, and the sintering holding time is 2 hours to 8 hours.

7. A method for preparing a solid-state magnesium-aluminum battery according to claim 3, characterized in that, Includes the following steps: Prepare the positive electrode and pretreat the flexible composite electrolyte and negative electrode; The positive electrode, the pretreated electrolyte, and the negative electrode are stacked and assembled to obtain the initial solid-state magnesium-aluminum battery; Pre-tightening pressure is applied to the initial solid-state magnesium-aluminum battery, followed by plastic film encapsulation; After being left to stand and age, a solid magnesium-aluminum battery is obtained.

8. The method for preparing a solid-state magnesium-aluminum battery according to claim 7, characterized in that, The preparation of the positive electrode specifically includes: A 1-3 nm layer of LiNbO3 was coated on the surface of the NMC811 cathode material, and the cathode was obtained after drying.

9. The method for preparing a solid-state magnesium-aluminum battery according to claim 8, characterized in that, Pretreatment of the flexible composite electrolyte specifically includes: The flexible composite electrolyte is heat-treated at 60℃~80℃ to maintain its water content at 3%~5%.

10. The method for preparing a solid-state magnesium-aluminum battery according to claim 8, characterized in that, The negative electrode undergoes pretreatment, specifically including: The negative electrode is subjected to plasma cleaning to activate its surface, and the surface-activated negative electrode is then modified.

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