Preparation method and application of oxygen vacancy Li2ZrO3 material

Abstract

The application discloses a preparation method and application of an oxygen vacancy Li2ZrO3 material and belongs to the field of lithium ion batteries. The oxygen vacancy Li2ZrO3 with uniform structure and high ionic conductivity is successfully prepared by using seaweed fiber, hydrochloric acid, ethanol, zirconium chloride, lithium carbonate and sodium borohydride as raw materials. The seaweed fiber is used as a template, so that the defect of excessively large crystal particle size caused by the traditional solid-phase sintering method is avoided to a certain extent; and the oxygen vacancy is manufactured in a certain concentration of sodium borohydride aqueous solution without changing the structure, so that the operation is simple and practical, and the product is controllable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a preparation method of oxygen vacancy Li2ZrO3 material and application thereof. BACKGROUND

[0002] There are many problems in energy storage and conversion that need to be solved, and the best choice is to manufacture renewable energy to reduce dependence on non-renewable energy. Among many energy storage technologies, lithium batteries play an increasingly important role. Compared with traditional liquid lithium batteries, lithium batteries using polymer electrolytes have better safety and development space, but the commonly used polymer electrolyte matrix such as PEO, PAN and the like is limited by low conductivity, which is difficult to support the use of high rate batteries, and the stability is difficult to control, and the use is limited at low temperature. Although inorganic solid electrolyte has strong ion transport capacity, it is difficult to be used on a large scale due to brittleness and poor interface contact with the electrode. Therefore, adding inorganic fast ion conductor as filler to the polymer electrolyte has become an important choice to solve the problems of ion transport and interface.

[0003] Seaweed fiber is a kind of degradable natural biological polysaccharide, which not only has low cost and is environment-friendly, but also has excellent eggshell structure which is beneficial to the combination of metal ions and enables it to obtain corresponding fiber morphology. Li2ZrO3 is a common fast ion conductor with good ion conductivity, which is commonly used in lithium ion battery electrode layers and electrolytes. SUMMARY

[0004] In view of the problems in the prior art, the present application uses natural and environmentally friendly renewable seaweed fiber as a matrix material, and designs fiber-like Li2ZrO3 using seaweed fiber with an eggshell structure as a template, and further increases oxygen vacancies by treating with a sodium borohydride aqueous solution to form a composite electrolyte with PEO, which has very excellent electrochemical performance.

[0005] The preparation process of the present application is simple, does not require expensive equipment, the obtained product has excellent performance, the preparation process is environmentally friendly, and has a broad prospect in the application of solid-state lithium ion batteries.

[0006] To achieve the above object, the present application provides the following technical scheme:

[0007] A preparation method of oxygen vacancy Li2ZrO3 material, comprising the following steps:

[0008] 1) Prepare an HCl aqueous solution, add a certain amount of seaweed fiber to the HCl aqueous solution, and stand at room temperature to obtain acidified seaweed fiber and wash with deionized water;

[0009] 2) Crosslinking the acidified seaweed fiber in ZrCl4 aqueous solution at room temperature to obtain zirconium alginate fiber, and washing with deionized water;

[0010] 3) Placing the washed zirconium alginate fiber in anhydrous ethanol, then adding lithium carbonate aqueous solution, and combining lithium ions with the zirconium alginate fiber by electrostatic adsorption, and drying;

[0011] 4) Segmentally heating the product of step 3) to 1000℃ in an air environment to obtain monoclinic Li2ZrO3, and treating the monoclinic Li2ZrO3 in sodium borohydride aqueous solution to form oxygen vacancy Li2ZrO3.

[0012] Preferably, the concentration of the HCl aqueous solution in step 1) is 1.0M, and the standing time is 2h.

[0013] Preferably, the ZrCl4 aqueous solution in step 2) is configured to be 0.05M by using 50%wt of the fiber ZrCl4, and the reaction time is 6h.

[0014] Preferably, the lithium carbonate is used in an amount equal to the mass of the fiber in step 3), and the reaction time is 2h.

[0015] Preferably, the segmental heating in step 4) is divided into room temperature to 450℃, holding for 3h, and then continuously heating to 1000℃, holding for 8h.

[0016] In addition, the application also provides an application of the oxygen vacancy Li2ZrO3 material prepared by the above method in a lithium ion battery solid-state electrolyte.

[0017] Preferably, the application of the oxygen vacancy Li2ZrO3 material in the lithium ion battery solid-state electrolyte is specifically:

[0018] 1) Dissolving lithium bis(trifluoromethanesulfonyl)imide and polyethylene oxide in anhydrous acetonitrile, and mixing uniformly to form a lithium bis(trifluoromethanesulfonyl)imide and polyethylene oxide mixture;

[0019] 2) Adding oxygen vacancy Li2ZrO3 powder into the lithium bis(trifluoromethanesulfonyl)imide and polyethylene oxide mixture, mixing uniformly, pouring into a mold, and drying in a vacuum environment to obtain an oxygen vacancy Li2ZrO3 / PEO lithium battery solid-state electrolyte.

[0020] Preferably, the mass of the oxygen vacancy Li2ZrO3 powder is 1-10% of the mass of the polyethylene oxide.

[0021] Preferably, the mass of the oxygen vacancy Li2ZrO3 powder is 3% of the mass of the polyethylene oxide.

[0022] The beneficial effects of the application are as follows:

[0023] 1. Using seaweed fiber, hydrochloric acid, ethanol, zirconium chloride, lithium carbonate, and sodium borohydride as raw materials, oxygen-vacant Li₂ZrO₃ with uniform structure and high ionic conductivity was successfully prepared. Using seaweed fiber as a template avoids to some extent the defect of excessively large crystal size caused by traditional solid-state sintering methods.

[0024] 2. The high-ionic-conductivity oxygen-vacancy Li₂ZrO₃ material of this invention utilizes eggshell-structured seaweed fibers as a template. After further increasing oxygen vacancies through treatment with sodium borohydride aqueous solution, it bonds well with a PEO-based polymer electrolyte, forming a composite electrolyte with excellent electrochemical performance. This electrolyte exhibits high lithium-ion transport number and conductivity without a significant decrease in mechanical strength. The assembled LFP / Li battery maintains stable cycling for over 300 cycles at 65°C and a current density of 2C (1C = 170 mAh g⁻¹), while retaining a capacity of 120 mAh g⁻¹. It also demonstrates good rate performance, with a specific capacity at 3C approaching 6 times that of PEO SPE.

[0025] 3. The preparation process of this invention is simple, does not require expensive equipment, yields products with excellent performance, and the preparation process is environmentally friendly, showing broad prospects for solid-state lithium-ion battery applications. Attached Figure Description

[0026] Figure 1 These are the scanning electron microscope images and elemental distribution maps of O-LZO obtained in Example 1;

[0027] Figure 2 The XRD patterns of O-LZO and LZO in Example 1, Comparative Example 1, and Comparative Example 2 are shown above, and the XRD patterns of PEO@O-LZO3%, PEO@LZO3%, and PEO SPE are shown below.

[0028] Figure 3 These are XPS plots of O-LZO and LZO with respect to the O element obtained in Example 1 and Comparative Example 1;

[0029] Figure 4 The lithium-ion transference number of the PEO@O-LZO 3% electrolyte prepared in Example 1 was measured by an electrochemical workstation using a Li / Li battery.

[0030] Figure 5 The lithium-ion transference number was measured by an electrochemical workstation using a Li / Li battery with the PEO@LZO 3% electrolyte prepared in Comparative Example 1.

[0031] Figure 6 The lithium-ion transference number of the PEO SPE electrolyte prepared in Comparative Example 3 was measured by an electrochemical workstation using a Li / Li battery.

[0032] Figure 7 is a plot of ionic conductivity at different temperatures measured by assembled SS / SS cells using the electrochemical workstation for Example 1, Example 2, Comparative Example 1 and 2.

[0033] Figure 8 is a long cycle plot of PEO@O-LZO 3% composition LFP / Li cell at 65 °C at 2C rate in Example 1;

[0034] Figure 9 is a rate performance plot of solid state electrolyte tested at 65 °C in Example 1, Comparative Example 1 and 2;

[0035] Figure 10 is a cycle stability plot measured at 65 °C for Li / Li cell assembled using solid state electrolyte in Example 1, Comparative Example 1 and 2;

[0036] Figure 11 is a performance plot obtained by linear sweep voltammetry at 65 °C for SS / CPE / Li cell assembled in Example 1, Comparative Example 1 and 2.

[0037] Figure 12 is a stress strain plot of product in Example 1, Example 3, Comparative Example 1 and 2. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Based on the examples in the present application, other similar examples obtained by those skilled in the art without making creative efforts should all belong to the scope of protection of the present application.

[0039] Example 1

[0040] 1) 2g of seaweed fiber (AF) was placed in 100 mL of 1M HC1 solution for 2h reaction, then taken out and washed with deionized water to obtain acidified seaweed fiber (H-AF).

[0041] 2) H-AF was placed in 0.05M ZrCl4 aqueous solution for 8h reaction, then taken out and washed with deionized water to obtain zirconium alginate fiber (Zr-AF).

[0042] 3) 2g of lithium carbonate was dissolved in 100 mL of a mixed solution of water and 200 mL of ethanol, and then Zr-AF was placed in the solution for 2h reaction, then taken out and completely dried to obtain Li-Zr-AF.

[0043] 4) Li-Zr-AF was heated to 450 °C at a rate of 2 °C per minute in an air environment, and then heated to 1000 °C at a rate of 1 °C per minute, and then kept for 8h.

[0044] The product Li2ZrO3(LZO) was taken out for cleaning, drying, and grinding.

[0045] 0.2 g of Li2ZrO3 was placed in 20 mL of 1 M aqueous sodium borohydride solution for 1 h to obtain oxygen vacancy lithium zirconate (O-LZO).

[0046] 5) 1 g of LiTFSI and 3 g of PEO were dissolved in 45 mL of anhydrous acetonitrile, and 0.09 g of O-LZO was added under stirring until uniform stirring, and then casting was performed. After drying at 60°C in a vacuum environment, PEO@O-LZO 3% electrolyte was obtained.

[0047] The above final product was cut into pieces and assembled into LFP / Li, SS / SS, Li / Li, etc. batteries in a glove box, and charge-discharge cycling and electrochemical tests were performed on a blue electric battery test system and an electrochemical workstation.

[0048] Example 2

[0049] The remaining steps were the same as in Example 1, except that:

[0050] 5) 1 g of LiTFSI and 3 g of PEO were dissolved in 45 mL of anhydrous acetonitrile, and 0.03 g of O-LZO was added under stirring until uniform stirring, and then casting was performed. After drying at 60°C in a vacuum environment, PEO@O-LZO 1% electrolyte was obtained.

[0051] Example 3

[0052] The remaining steps were the same as in Example 1, except that:

[0053] 5) 1 g of LiTFSI and 3 g of PEO were dissolved in 45 mL of anhydrous acetonitrile, and 0.3 g of O-LZO was added under stirring until uniform stirring, and then casting was performed. After drying at 60°C in a vacuum environment, PEO@O-LZO 10% electrolyte was obtained.

[0054] Comparative Example 1

[0055] 1) 2 g of seaweed fiber (AF) was placed in 100 mL of 1M HCl solution for 2 h, then taken out and washed with deionized water to obtain acidified seaweed fiber (H-AF).

[0056] 2) The H-AF was placed in 0.05M ZrCl4 aqueous solution for 8 h, then taken out and washed with deionized water to obtain zirconium alginate fiber (Zr-AF).

[0057] 3) 2 g of lithium carbonate was dissolved in 100 mL of a mixed solution of water and 200 mL of ethanol, and the Zr-AF was placed in it and stirred uniformly for 2 h, then taken out and completely dried to obtain Li-Zr-AF.

[0058] 4) Li-Zr-AF was heated to 450℃ at 2℃ / min in air, and then heated to 1000℃ at 1℃ / min for 8h.

[0059] The product Li2ZrO3(LZO) was taken out, washed, dried and grinded.

[0060] 5) 1g of LiTFSI and 3g of PEO were dissolved in 45mL of anhydrous acetonitrile, and 0.09g of Li2ZrO3 was added and stirred until uniform, then cast, and dried at 60℃ in a vacuum environment to obtain PEO@LZO 3% electrolyte.

[0061] The final product was cut and assembled into LFP / Li, SS / SS, Li / Li, etc. batteries in a glove box, and the charge-discharge cycles and electrochemical tests were performed on a blue electric battery test system and an electrochemical workstation.

[0062] Comparative Example 2

[0063] 1g of LiTFSI and 3g of PEO were dissolved in 45mL of anhydrous acetonitrile, and stirred until uniform, then cast, and dried at 60℃ in a vacuum environment to obtain PEO electrolyte.

[0064] The final product was cut and assembled into LFP / Li, SS / SS, Li / Li, etc. batteries in a glove box, and the charge-discharge cycles and electrochemical tests were performed on a blue electric battery test system and an electrochemical workstation.

[0065] From Figure 1 Visible fiber structure, uniform Zr distribution.

[0066] From Figure 2 The above figure shows that LZO and O-LZO both conform to the structure of monoclinic Li2ZrO3, indicating that the increase of oxygen vacancies does not cause phase change; the lower crystallinity of PEO after adding LZO and O-LZO is more conducive to lithium ion transport.

[0067] From Figure 3 It is observed that O-LZO has a new characteristic peak corresponding to the Zr-O bond at the position of binding energy 290eV, which can reflect the successful creation of oxygen vacancies on O-LZO.

[0068] From Figures 4-6It can be seen that after adding LZO, the interfacial impedance of PEO@LZO electrolyte has risen, but the lithium ion transfer number is 0.39, which is still greater than 0.26 of PEO SPE. It can be observed that after adding O-LZO, the interfacial impedance has decreased obviously, and the transfer number has increased to 0.57, which is more conducive to the transport of lithium ions in the electrolyte.

[0069] Figure 7 It can be obviously observed that PEO@O-LZO3% has the optimal lithium ion conductivity within the test temperature, which indicates that it plays a greater role in the transmission of lithium ions in the electrolyte, and is conducive to the stable cycle and use under large current of the assembled battery.

[0070] Figure 8 It can be seen that after 300 cycles, the coulombic efficiency is always maintained above 99.5%, and the final capacity is stable at 120mAh g -1 , with excellent capacity retention and long-term working ability.

[0071] Figure 9 It can be obviously observed that PEO@O-LZO3% and PEO@LZO3% both have good rate performance, and PEO@O-LZO3% has obvious advantages at high rate, which indicates that the presence of oxygen vacancies further improves the lithium ion transport capacity. At a current density of 3C, the capacity of PEO@O-LZO3% is nearly 6 times that of PEO SPE battery.

[0072] Figure 10 It can be observed that at a current density of 0.1mA cm -2 , the batteries using PEO@O-LZO3% and PEO@LZO3% both maintain stable cycle within 950h without obvious voltage rise, which is obviously improved compared with the cycle life of PEO SPE close to 100h, and the polarization voltage is small, and the interface contact with Li sheet is good.

[0073] Figure 11 It can be seen that the prepared PEO@O-LZO3% and PEO@LZO3% still remain stable at a voltage close to 4.8V or above, which means that the electrolyte can adapt to higher voltage electrodes. Compared with pure PEO with a voltage lower than 4.0V, the problem of solid-state polymer electrolyte being difficult to adapt to high-voltage electrodes is effectively solved.

[0074] Figure 12 It can be seen that with the addition of a small amount of O-LZO, the mechanical strength of the electrolyte does not decrease obviously, which can inhibit the generation of lithium dendrites to a certain extent. However, when more O-LZO is added, the mechanical strength decreases obviously. Considering the ion transport capacity and mechanical strength, the optimal comprehensive performance is obtained when the addition amount of O-LZO is 3% of the mass of PEO.

[0075] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes only one independent technical solution, and the specification is described in this way only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for preparing oxygen-vacancy Li₂ZrO₃ material, characterized in that, Includes the following steps: 1) Prepare an HCl aqueous solution, add a certain mass of seaweed fiber to the HCl aqueous solution, let it stand at room temperature to obtain acidified seaweed fiber, and wash it with deionized water; 2) Acidified seaweed fibers were cross-linked in ZrCl4 aqueous solution at room temperature to obtain zirconium alginate fibers, which were then washed with deionized water. 3) Place the cleaned zirconium alginate fiber in anhydrous ethanol, then add lithium carbonate aqueous solution, and use electrostatic adsorption to combine lithium ions with zirconium alginate fiber, then dry. 4) The product of step 3) is heated in stages to 1000℃ in air to obtain monoclinic Li2ZrO3, which is then treated in sodium borohydride aqueous solution to form oxygen vacancy Li2ZrO3.

2. The method for preparing oxygen-vacancy Li₂ZrO₃ material according to claim 1, characterized in that, The concentration of the HCl aqueous solution mentioned in step 1) is 1.0M, and the standing time is 2h.

3. The method for preparing oxygen-vacancy Li₂ZrO₃ material according to claim 1, characterized in that, The ZrCl4 aqueous solution mentioned in step 2) is prepared into a 0.05M aqueous solution by using ZrCl4 accounting for 50% wt of the fiber, and the reaction time is 6h.

4. The method for preparing oxygen-vacancy Li₂ZrO₃ material according to claim 1, characterized in that, In step 3), the amount of lithium carbonate used is the same as the weight of the fiber, and the reaction time is 2 hours.

5. The method for preparing oxygen-vacancy Li₂ZrO₃ material according to claim 1, characterized in that, In step 4, the temperature is raised in stages: from room temperature to 450℃ and then kept at that temperature for 3 hours; then the temperature is raised to 1000℃ and kept at that temperature for 8 hours.

6. The application of oxygen-vacancy Li2ZrO3 material prepared by the method according to any one of claims 1-5 in solid electrolytes of lithium-ion batteries.

7. The application according to claim 6, characterized in that, Specifically: 1) Dissolve lithium bis(trifluoromethanesulfonyl)imide and polyethylene oxide in anhydrous acetonitrile and mix them evenly to form a mixture of lithium bis(trifluoromethanesulfonyl)imide and polyethylene oxide; 2) The oxygen vacancy Li2ZrO3 powder was added to the mixture of lithium bis(trifluoromethanesulfonyl)imide and polyethylene oxide and mixed evenly. The mixture was then poured into a mold and dried under vacuum to obtain the oxygen vacancy Li2ZrO3 / PEO lithium battery solid electrolyte.

8. The application according to claim 7, characterized in that, The mass of the oxygen-vacancy Li2ZrO3 powder is 1-10% of the mass of the polyethylene oxide.

9. The application according to claim 8, characterized in that, The mass of the oxygen-vacancy Li2ZrO3 powder is 3% of the mass of polyethylene oxide.

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