All-solid-state composite electrolyte based on glass fiber vertical array structure and preparation method thereof

[0040] Example 1

[0041] (1) Polyethylene oxide (PEO, molecular weight 60W) and lithium bistrifluoromethanesulfonimide (LiTFSI) were prepared in a molar ratio of 15:1, and mixed thoroughly.

[0042] (2) Li is selected as the solid electrolyte material in this embodiment. 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 , 500g total mass of lithium carbonate, alumina, germanium dioxide, ammonium dihydrogen phosphate powders were weighed according to the stoichiometric ratio and mixed and ball-milled, and an additional 5wt% lithium carbonate was added to make up for the volatilization of the lithium source during the high-temperature melting process. After fully mixing, put the mixed powder in a corundum crucible, and put it in a high temperature electric melting furnace at 1350 o C was kept for 30 minutes, until a clear molten glass was formed, the glass was transferred to a platinum alloy grooved bushing heated by a high-temperature electrofusion electrode, and the temperature in the bushing was controlled at 1250 ° C. It can be seen from the glass fiber drawing device shown in the accompanying drawing that the molten glass 1 flows out along the leak nozzle 3 at the bottom of the platinum alloy slotted leak plate 2, and is stretched into glass fiber by the rotating reel 5 at the outlet. figure 1 6 shows the rotating reel 6, that is, the reel 5 in a rotating state. The diameter of the glass fiber can be controlled according to the viscosity of the glass and the drawing speed, and the LAGP glass fiber with a diameter of 10 μm can be drawn. The so-called glass fiber in the present invention refers to the glass fiber. figure 2 shown, where the horizontal axis is the temperature change parameter, and the vertical axis is the viscosity. Finally, place the drawn glass fiber in a muffle furnace 850 o C heat treatment for 6h, that is, to obtain LAGP glass fiber electrolyte.

[0043] (3) Take an appropriate amount of drawn LAGP glass fiber electrolyte and cut it into the same length of 15cm. Generally speaking, the glass fiber electrolyte used in experiments and experiments is cut into 10-15cm, and the industrial use is generally cut into a cutting length that can be adjusted according to the mold. Glass fibers of equal length of 1-5m can be arranged neatly and horizontally in the stainless steel mold; the mixed powder of polymer and lithium salt is added to the neatly arranged glass fiber electrolyte, and this step is repeated several times, and the specific folding times are as required. The amount of mixing is determined, and the multi-layer glass fiber electrolyte/polymer/lithium salt mixture is superimposed. For the specific process, please refer to the appendix. image 3 After vacuum hot pressing, longitudinal sectioning after drying, an all-solid-state composite electrolyte with a vertical array structure with a thickness of 500 μm is obtained, and the mass ratio of polymer to inorganic solid-state electrolyte is 1:9.

[0044] The structure diagram of the all-solid-state composite electrolyte based on the glass fiber vertical array structure is shown in Fig. 4(a) and Fig. 4(b), the scanning electron microscope Fig. 4(a) is the surface structure diagram of the all-solid-state composite electrolyte, and the image scale is 50 μm; scanning electron microscope Figure 4(b) is the cross-sectional structure diagram of the all-solid composite electrolyte, the image scale is 20 μm, the glass fiber diameter in Figure 4(a) and Figure 4(b) is 10 μm, and the polymer/inorganic mass ratio is 1:9.

[0045] After testing, the all-solid-state composite electrolyte based on the vertical array structure prepared in this example has a significant improvement in room temperature ionic conductivity compared with the ordinary PEO-LAGP composite electrolyte (LAGP is introduced in the form of powder at the same weight ratio). Figure 5 It can be seen from the comparison diagram of the AC impedance spectrum (EIS) that the horizontal axis Z' represents the real part of the impedance, and the vertical -Z" represents the imaginary part of the impedance. The curve of the frequency change, the curve 5b in the figure is the curve of the all-solid-state composite electrolyte with the virtual and real impedance with the frequency of the embodiment, the room temperature ionic conductivity of this embodiment can reach 3.3×10 -4 S/cm.

[0046] from the attached Image 6 It can be seen from the figure that the use of this all-solid-state composite electrolyte with a vertical array structure based on the glass fiber drawing technology to assemble a metal lithium-lithium iron phosphate full battery, compared with the ordinary polyethylene oxide-germanium aluminum lithium phosphate composite electrolyte, the curve a is the change of the specific capacity of the lithium metal-lithium iron phosphate battery assembled with the common all-solid-state composite electrolyte during the first cycle, curve b is the specific capacity of the lithium metal-lithium iron phosphate battery assembled with the common all-solid-state composite electrolyte at the tenth cycle Changes; curve c is the change of the specific capacity of the lithium metal-lithium iron phosphate battery assembled with the all-solid-state composite electrolyte with a glass fiber vertical array structure in the present embodiment during the first cycle, and the curve d is the present embodiment with a glass fiber vertical The change in specific capacity of the lithium metal-lithium iron phosphate battery assembled with the all-solid-state composite electrolyte of the array structure at the tenth cycle. From the comparison of these graphs, it can be seen that the ratio of the all-solid composite electrolyte based on the vertical glass fiber array structure in this example is The capacity has been significantly improved.

[0047] Example 2

[0048] (1) Combine polyvinylidene fluoride (PVDF, molecular weight 100W) with lithium hexafluorophosphate LiPF 6 Formulate in a 25:1 molar ratio and mix well.

[0049] (2) Li is selected as the solid electrolyte material in this embodiment. 1.5 Al 0.5 Ti 1.5 (PO 4 ) 3 , 500g total mass of lithium carbonate, aluminum oxide, titanium dioxide, ammonium dihydrogen phosphate powder will be weighed according to the stoichiometric ratio and mixed and ball milled, and an additional 5wt% lithium carbonate will be added to make up for the volatilization of the lithium source during the high temperature melting process. After thorough mixing, the mixed powder was placed in an alumina crucible, at 1400 o C for 30 minutes in a high-temperature furnace to a clear and molten state, and then transfer the glass liquid to the platinum alloy slot bushing, and the temperature in the platinum alloy slot bushing is controlled at 1300 o C. The molten glass flows out from the leak nozzle at the bottom of the platinum alloy slotted bushing, and is drawn into glass fibers by the rotating reel at the outlet. The glass viscosity is regulated by controlling the melting temperature inside the platinum alloy slot bushing, and the size of the glass fiber is controlled by adjusting the rotation speed of the reel, and LATP glass fibers with a diameter of 10 μm are drawn. Finally, place the drawn glass fiber in a muffle furnace 900 o C heat treatment for 6h, the LATP glass fiber electrolyte is obtained.

[0050] (3) Take an appropriate amount of drawn glass fiber bundles and cut them into the same length of 15cm, lay them flat in a stainless steel mold, assemble the mold with a vertical array of glass fibers, and add the mixed powder of polymer and lithium salt to the well-arranged glass fiber electrolyte, And repeat this step for many times, superimpose the multi-layer glass fiber electrolyte/polymer/lithium salt mixture; after vacuum hot pressing, longitudinally sectioning to obtain an all-solid composite electrolyte with a thickness of 500 μm and a vertical array structure, the polymer electrolyte and solid The mass ratio of electrolytes is 1:8.

[0051] After testing, the room temperature ionic conductivity of the all-solid-state composite electrolyte with a vertical array structure based on the glass fiber drawing technology prepared in this example can reach 2.9×10 -4 S/cm.

[0052] Example 3

[0053] (1) Combine polyethylene glycol (PEG, molecular weight 10000) with lithium hexafluorophosphate LiPF 6 Formulate in a 25:1 molar ratio and mix well.

[0054] (2) Li is selected as the solid electrolyte material in this embodiment. 1.5 Al 0.5 Ti 1.5 (PO 4 ) 3 , 500g of lithium carbonate, alumina, germanium dioxide, and ammonium dihydrogen phosphate powders were mixed and ball-milled according to the stoichiometric ratio, and an additional 5wt% of lithium carbonate was added to make up for the volatilization of the lithium source during the high-temperature melting process. After fully mixing, put the mixed powder in a corundum crucible, and put it in a high temperature electric melting furnace at 1350 o C for 30 minutes, until a clear molten glass is formed, the molten glass is transferred to the platinum alloy groove type bushing, and the temperature in the platinum alloy groove type bushing is controlled at 1250 °s C. The molten glass flows out from the leak nozzle at the bottom of the platinum alloy slotted bushing, and is drawn into glass fibers by the rotating reel at the outlet. The viscosity of the glass is regulated by controlling the melting temperature inside the platinum alloy groove bushing, and the size of the glass fiber is controlled by adjusting the rotation speed of the reel, and the LAGP glass fiber electrolyte with a diameter of 10 μm is drawn. Finally, place the drawn glass fiber in a muffle furnace 850 o C heat treatment for 6h, the LAGP glass fiber electrolyte is obtained.

[0055] (3) Take an appropriate amount of drawn glass fiber and cut it into the same length of 10cm, use the vertical array of glass fiber to assemble the mold, add the mixed powder of polymer and lithium salt to the well-arranged glass fiber electrolyte, and repeat this step many times, stacking Multilayer glass fiber electrolyte/polymer/lithium salt mixture; after hot pressing in vacuum, longitudinally sectioning a composite electrolyte sheet with a thickness of 300 μm and a vertical array structure, the mass ratio of polymer electrolyte to solid electrolyte is 1:8.

[0056] After testing, the room temperature ionic conductivity of the all-solid-state composite electrolyte based on the glass fiber vertical array structure prepared in this example can reach 1.5×10 -4 S/cm.

[0057] From the above, it can be seen that the all-solid-state composite electrolyte based on the glass fiber vertical array structure of the present invention not only has higher ionic conductivity, but also has a higher specific capacity of the all-solid-state lithium ion battery assembled by using the all-solid-state composite electrolyte prepared by the present invention. High (119.7mAh/g), which improves the overall performance of the composite electrolyte.