CN102502789B - Alkaline-earth metal germanate nanomaterial and its preparation method and application as lithium-ion battery negative electrode material - Google Patents

Abstract

The invention discloses an alkaline earth metal germanate nanometer material, a preparation method thereof and an application as a negative electrode material of a lithium ion battery. The method comprises the following steps: 1) mixing the aqueous solution of the alkaline earth metal salt with the germanium source compound GeO to obtain a mixed solution; 2) heating the mixed solution obtained in step 1) in a polytetrafluoroethylene _- lined autoclave The reaction is carried out, and the reaction is completed and cooled to obtain the alkaline earth metal germanate nanomaterial. The method has simple process, abundant and easy-to-obtain raw materials, is suitable for large-scale production, and has a high degree of practicality, and the obtained alkaline earth metal germanate is a nanometer material with high actual capacity, which can be directly used as the negative electrode material of lithium ion battery, improving the Germanium-based materials, as anode materials for lithium-ion batteries, have poor cycle performance and severe volume changes during charging and discharging, so they can be directly used as electrode materials for lithium-ion batteries.

Description

Alkaline-earth metal germanate nanomaterial and its preparation method and application as lithium-ion battery negative electrode material

technical field

The invention relates to an alkaline earth metal germanate nanometer material, a preparation method thereof and an application as a negative electrode material of a lithium ion battery.

Background technique

With the rapid development of energy, transportation, information, national defense and other fields, higher requirements are put forward for the performance of energy storage devices. Lithium-ion batteries have become a popular choice for portable electronics such as notebook computers, tablet computers, and mobile phones because of their outstanding advantages such as high working voltage, high energy density, large capacity, small self-discharge, good cycle performance, long service life, light weight, and small size. Ideal power supply for devices. In order to meet the actual use requirements such as safety, stability, and long standby time, high-capacity, long-life lithium-ion batteries have become an important research direction for their development. Since the current specific capacity of positive electrode materials is relatively low, there is not much room for capacity improvement, so the development of high-capacity lithium-ion batteries is mainly concentrated on negative electrode materials. At present, the commercially used anode material is carbon material, and its theoretical specific capacity is only 372mAh/g. Therefore, finding a high-capacity anode material that can replace carbon has become an important research direction.

Germanium has a high theoretical specific capacity (1600mAh/g), high lithium ion mobility and conductivity, and is widely distributed in the earth, low cost, and environmentally friendly, so it has become a promising negative electrode material . However, during the charging and discharging process, the lithium intercalation and deintercalation process of germanium is accompanied by a volume change of 370%, causing electrode cracking and active material falling off from the current collector, and the structure is gradually pulverized and destroyed, resulting in a continuous decline in capacity during multiple cycles. In response to this problem, in recent years, the cycleability of germanium anode materials has been improved mainly through the following aspects:

1. Nano elemental germanium material

In order to improve the cycle performance of elemental germanium, the nanometerization of germanium can reduce its volume change to a certain extent and reduce the internal stress of the electrode. Although the volume of germanium nanowires and germanium nanotubes will expand and shrink during the charging and discharging process, and the length and diameter will also change, the one-dimensional germanium nanowires or tubes can effectively buffer the volume change, making the structure It does not break, and at the same time, electrons can effectively flow from the current collector to the nanowire or tube, and the electrolyte infiltrated in the gap between the winding of the nanowire or tube shortens the diffusion path of lithium ions, making it have good cycle performance and high rate discharge performance. However, although germanium nanowires and nanotubes have good recyclability, their preparation process is complicated, the output is low, and the cost of raw materials is high. At present, they are limited to the basic research stage, and it is difficult to industrialize large-scale production, and the degree of practicality is low.

2. Germanium-based composite materials

The current research on germanium-based composites mainly focuses on germanium-carbon composites. Because carbon has better flexibility, good electronic conductivity, lower density, and smaller volume expansion (10%), it becomes the active matrix of germanium-based negative electrode materials. After carbon coating on the surface of germanium, it can effectively prevent the oxidation of elemental germanium, reduce the irreversible capacity, and also buffer the volume change during charge and discharge, prevent the agglomeration and growth of germanium particles, thereby improving the capacity retention performance of germanium-based negative electrode materials. However, germanium-carbon composite materials also have some problems. Vapor deposition and polymerization-pyrolysis methods are usually used for preparation. These methods also have complicated preparation processes, low yields, and are difficult to produce on a large scale.

In addition to using the above-mentioned germanium-carbon composite materials, there are also studies using germanium compounds, such as germanium dioxide (GeO ₂ ), germanium disulfide (GeS ₂ ), and lithium germanium phosphate (LiGe ₂ (PO ₄ ) ₃ ) as negative electrode materials. In the process of charging and discharging for the first time, germanium particles will be formed and embedded in matrix materials such as Li ₂ O, Li ₂ S, Li ₃ PO ₄ , which also play a role in buffering volume changes, but the cycle performance still cannot meet the actual requirements. And the specific capacity is low. Therefore, the development of a high-performance germanium-based nano-anode material suitable for large-scale production is of great significance to the development of high-performance lithium-ion batteries.

Contents of the invention

The purpose of the present invention is to provide an alkaline-earth metal germanate nano-material, its preparation method and its application as a lithium-ion battery negative electrode material.

The method for preparing alkaline earth metal germanate nanomaterial provided by the invention comprises the following steps:

1) mixing an aqueous solution of an alkaline earth metal salt with a germanium source compound _GeO to obtain a mixed solution;

2) The mixed solution obtained in step 1) is heated in a polytetrafluoroethylene-lined reactor and then reacted, and cooled after the reaction is completed to obtain the alkaline earth metal germanate nanomaterial.

In the above method, the alkaline earth metal salt is selected from at least one of acetate and hydroxide of the following metal elements: Mg, Ca, Sr and Ba; the alkaline earth metal salt and GeO _The amount of feed material The ratio is 1: 4-10: 1; Wherein, for calcium salt and _GeO The amount ratio of feed material is preferably 2: 7-2: 1, specifically can be 2: 7-1: 1 or 1: 1-2 : 1; For strontium salt and GeO ₂ The ratio of the amount of feeding material is preferably 1: 4-2: 1, specifically can be 1: 4-1: 2 or 1: 2-2: 1; For barium salt and GeO ₂ The ratio of the amount of the feed material is preferably 5: 1-10: 1, specifically 5: 1-7: 1 or 7: 1-10: 1; for magnesium salt and _GeO The ratio of the amount of the feed material is preferably 1: 1-5:1, specifically 1:1-2:1 or 2:1-5:1. The concentration of the aqueous solution of the alkaline earth metal salt is based on the complete dissolution of the alkaline earth metal salt.

In the step 3), in the heating step, the heating rate is 5-30°C/min, specifically 5-20°C/min, 5-10°C/min, 10-30°C/min, 10-20 °C/min or 20-30°C/min; in the reaction step, the temperature is 180°C-200°C, specifically 180-190°C or 190-200°C, and the time is 12-48 hours, specifically 12- 24 hours, 12-36 hours, 24-48 hours, 24-36 hours or 36-48 hours; the volume of the polytetrafluoroethylene lining is 25mL-100mL, specifically 25mL-50mL or 50-100mL; In the above cooling step, the cooling method can be natural cooling to room temperature.

In addition, the above method further includes the following steps: after the reaction is completed, the reaction system obtained after cooling is washed with deionized water, centrifuged and then dried to obtain the pure alkaline earth metal germanate nanomaterial.

The alkaline earth metal germanate nanomaterial prepared according to the above method also belongs to the protection scope of the present invention. The alkaline earth metal germanate nanomaterial is at least one of alkaline earth metal magnesium germanate nanomaterial, alkaline earth metal calcium germanate nanomaterial, alkaline earth metal strontium germanate nanomaterial and alkaline earth metal barium germanate nanomaterial;

Wherein, in the alkaline earth metal magnesium germanate nanomaterial, the apparent physical state of the magnesium germanate is magnesium germanate nanosheets, the diameter of the nanosheets is 2-10 μm, and the thickness is 20-80 nm;

The apparent physical state of the calcium germanate is a calcium germanate one-dimensional nanowire, the length of the calcium germanate one-dimensional nanowire is 20-1000 μm, and the diameter is 20-70 nm;

The apparent physical state of the strontium germanate is a strontium germanate one-dimensional nanowire, the length of the strontium germanate one-dimensional nanowire is 50-1000 μm, and the diameter is 20-80 nm;

The apparent physical state of the barium germanate is one-dimensional barium germanate nanowires, the length of the one-dimensional barium germanate nanowires is 50-500 μm, and the diameter is 20-60 nm.

The above-mentioned application of the alkaline earth metal germanate nanomaterial provided by the present invention as a battery electrode material, as well as energy storage elements or portable electronic devices containing the alkaline earth metal germanate nanomaterial also belong to the protection scope of the present invention. Wherein, the battery electrode material is preferably a negative electrode material of a lithium ion battery; the energy storage element is preferably a negative electrode material of a lithium ion battery; the portable electronic device is a mobile phone, a camera, a video camera, MP3, MP4 or a notebook computer.

Compared with the prior art, the method for preparing the alkaline earth metal germanate nanomaterial provided by the invention has simple process, easy-to-obtain raw materials, high yield, is suitable for large-scale production, and has a high degree of practicality. And the obtained alkaline earth metal germanate is a nanometer material, which improves the poor cycle performance of the germanium material as the negative electrode material of the lithium ion battery, and the problem of drastic volume change during the charging and discharging process, and can be directly used as the electrode material of the lithium ion battery.

Description of drawings

Fig. 1 is the X-ray diffraction (XRD) pattern of the calcium germanate nanomaterial that embodiment 1 obtains.

Fig. 2 is the scanning electron micrograph of the calcium germanate nano material that embodiment 1 obtains.

Fig. 3 is the charge and discharge curves of the first three cycles under the condition of 100mA/g constant current charge and discharge with the calcium germanate nanomaterial obtained in Example 1 as the negative electrode material.

FIG. 4 is an X-ray diffraction (XRD) spectrum of the strontium germanate nanomaterial obtained in Example 4.

FIG. 5 is a scanning electron micrograph of the strontium germanate nanomaterial obtained in Example 4.

Fig. 6 is the charge and discharge curves of the first three cycles under the condition of 100mA/g constant current charge and discharge with the strontium germanate nanomaterial obtained in Example 4 as the negative electrode material.

FIG. 7 is an X-ray diffraction (XRD) spectrum of the barium germanate nanomaterial obtained in Example 7.

FIG. 8 is a scanning electron micrograph of the barium germanate nanomaterial obtained in Example 7.

Fig. 9 is the charging and discharging curves of the first three cycles under the constant current charging and discharging condition of 100mA/g when the barium germanate nanomaterial obtained in Example 7 is used as the negative electrode material.

FIG. 10 is an X-ray diffraction (XRD) spectrum of the magnesium germanate nanomaterial obtained in Example 10.

11 is a scanning electron micrograph of the magnesium germanate nanomaterial obtained in Example 10.

Fig. 12 is the charge and discharge curves of the first three cycles under the condition of 100mA/g constant current charge and discharge with the magnesium germanate nanomaterial obtained in Example 10 as the negative electrode material.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods are conventional methods unless otherwise specified. The materials can be obtained from public commercial sources unless otherwise specified.

Embodiment 1, the preparation of calcium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Ca(CH ₃ COO) ₂ ·H ₂ O:GeO ₂ =2:7, ultrasonically stir in water for 30min, mix well and transfer to the lining of a 25mL polytetrafluoroethylene autoclave , put it into a stainless steel high-pressure reactor, raise the temperature from room temperature to 180 °C at a rate of 10 °C/min, and keep it for 24 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge Dry to obtain a white powder.

Characterization of calcium germanate nanomaterials:

The structure was determined by powder X-ray diffractometer (Rigaku DmaxrB, CuK _α -ray), and the results are shown in Fig. 1 . As can be seen from the figure, there is no impurity peak in the spectrogram, indicating that the product has high purity and is the target product calcium germanate.

The length and diameter of the calcium germanate obtained under the above conditions were detected with a Japanese electron scanning electron microscope (JEOL-6700F), and the results showed that the obtained calcium germanate was a one-dimensional nanowire structure with a length of 20-1000 μm and a diameter of 20-70 nm (See Figure 2).

Electrochemical performance characterization of calcium germanate:

The calcium germanate prepared in Example 1, acetylene black and polyvinylidene fluoride (binder) were mixed at a mass ratio of 70:20:10 to form a slurry, and evenly coated on the copper foil current collector to obtain a negative electrode Diaphragm. A metal lithium sheet was used as the positive electrode, a polypropylene microporous membrane (Celgard 2400) was used as the diaphragm, and 1mol/L LiPF ₆ (the solvent was a mixture of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:1) was used as the electrolyte. A Swagelok-type mock battery was assembled in an argon-protected glove box.

The battery assembled above was subjected to a constant current charge and discharge test on an Arbin BT2000 charge and discharge tester. The charge and discharge rate was 100mA/g, and the charge and discharge voltage range was 0-3.0V. The charge and discharge curves are shown in Figure 3. The calcium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Embodiment 2, the preparation of calcium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Ca(OH) ₂ :GeO ₂ =1:1, ultrasonically stir in water for 30min, mix evenly, transfer to a 50mL polytetrafluoroethylene autoclave lining, put it into In a stainless steel high-pressure reactor, the temperature was raised from room temperature to 200 °C at a rate of 20 °C/min, and kept for 48 hours, then naturally cooled to room temperature, washed with deionized water three times, centrifuged and dried to obtain a white powder.

The structure confirmation results and the apparent physical form, length and diameter of the white powder are the same as in Example 1.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are exactly the same as in Example 1. The calcium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Embodiment 3, the preparation of calcium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Ca(CH ₃ COO) ₂ ·H ₂ O:GeO ₂ =2:1, ultrasonically stir in water for 30min, mix well and transfer to a 25mL polytetrafluoroethylene autoclave lining , put it into a stainless steel high-pressure reactor, raise the temperature from room temperature to 200 °C at a heating rate of 30 °C/min, and keep it for 24 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge Dry to obtain a white powder.

The structure confirmation results and the apparent physical form, length and diameter of the white powder are the same as in Example 1.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are the same as in Example 1. The calcium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Embodiment 4, preparation of strontium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Sr(CH ₃ COO) ₂ ·1/2H ₂ O:GeO ₂ =1:4, ultrasonically stir in water for 30min, mix well and transfer to a 25mL polytetrafluoroethylene autoclave In the lining, put it into a stainless steel high-pressure reactor, raise the temperature from room temperature to 180 °C at a rate of 5 °C/min, and keep it for 24 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge After separation and drying, a white powder was obtained.

Characterization of strontium germanate nanomaterials:

The structure was determined by powder X-ray diffractometer (Rigaku DmaxrB, CuK _α -ray), and the results are shown in FIG. 4 . As can be seen from the figure, there is no impurity peak in the spectrogram, indicating that the product has high purity and is the target product strontium germanate.

The length and diameter of the strontium germanate obtained under the above conditions were detected by a Japanese electron scanning electron microscope (JEOL-6700F), and the results showed that the obtained strontium germanate was a one-dimensional nanowire structure with a length of 50-1000 μm and a diameter of 20-80 nm (See Figure 5).

Electrochemical performance characterization of strontium germanate:

The strontium germanate prepared in Example 4, acetylene black and polyvinylidene fluoride (binder) were mixed at a mass ratio of 70:20:10 to form a slurry, and evenly coated on the copper foil current collector to obtain a negative electrode Diaphragm. A metal lithium sheet was used as the positive electrode, a polypropylene microporous membrane (Celgard 2400) was used as the diaphragm, and 1mol/L LiPF ₆ (the solvent was a mixture of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:1) was used as the electrolyte. A Swagelok-type mock battery was assembled in an argon-protected glove box.

The battery assembled above was subjected to a constant current charge and discharge test on an Arbin BT2000 charge and discharge tester. The charge and discharge rate was 100mA/g, and the charge and discharge voltage range was 0-3.0V. The charge and discharge curves are shown in Figure 6. The strontium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Embodiment 5, the preparation of strontium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Sr(OH) ₂ ·8H ₂ O:GeO ₂ =1:2, ultrasonically stir in water for 30 minutes, mix well and transfer to a 100mL polytetrafluoroethylene autoclave lining, Put it into a stainless steel autoclave, raise the temperature from room temperature to 200 °C at a rate of 30 °C/min, and keep it for 12 hours, then naturally cool to room temperature, wash with deionized water three times, and dry after centrifugation. A white powder was obtained.

The structure confirmation results and apparent physical form, length and diameter of the white powder are the same as in Example 4.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are the same as in Example 4. The strontium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Embodiment 6, preparation of strontium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Sr(CH ₃ COO) ₂ ·1/2H ₂ O:GeO ₂ =2:1, ultrasonically stir in water for 30min, mix well and transfer to a 50mL polytetrafluoroethylene autoclave Put it into a stainless steel high-pressure reactor, raise the temperature from room temperature to 190 °C at a rate of 10 °C/min, and keep it for 48 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge After separation and drying, a white powder was obtained.

The structure confirmation results and apparent physical form, length and diameter of the white powder are the same as in Example 4.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are the same as in Example 4. The strontium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Embodiment 7, the preparation of barium germanate nano material and its electrochemical performance test

Weigh according to the ratio of Ba(CH ₃ COO) ₂ ·H ₂ O:GeO ₂ =10:1, ultrasonically stir in water for 30min, mix evenly and transfer to a 25mL polytetrafluoroethylene autoclave lining , put it into a stainless steel high-pressure reactor, raise the temperature from room temperature to 180 °C at a rate of 10 °C/min, and keep it for 24 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge Dry to obtain a white powder.

Characterization of barium germanate nanomaterials:

The structure was determined by powder X-ray diffractometer (Rigaku DmaxrB, CuK _α -ray), and the results are shown in FIG. 7 . As can be seen from the figure, there is no impurity peak in the spectrogram, indicating that the product has high purity and is the target product barium germanate.

The length and diameter of the barium germanate obtained under the above conditions were detected by a Japanese electron scanning electron microscope (JEOL-6700F). The results showed that the obtained barium germanate was a one-dimensional nanowire structure with a length of 50-500 μm and a diameter of 20-60 nm. (See Figure 8).

Electrochemical performance characterization of barium germanate:

The barium germanate prepared in Example 7, acetylene black and polyvinylidene fluoride (binder) were mixed at a mass ratio of 70:20:10 to form a slurry, and evenly coated on the copper foil current collector to obtain a negative electrode Diaphragm. A metal lithium sheet was used as the positive electrode, a polypropylene microporous membrane (Celgard 2400) was used as the diaphragm, and 1mol/L LiPF ₆ (the solvent was a mixture of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:1) was used as the electrolyte. A Swagelok-type mock battery was assembled in an argon-protected glove box.

The battery assembled above was subjected to a constant current charge and discharge test on an Arbin BT2000 charge and discharge tester. The charge and discharge rate was 100mA/g, and the charge and discharge voltage range was 0-3.0V. The charge and discharge curves are shown in Figure 9. The barium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Example 8, preparation of barium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Ba(CH ₃ COO) ₂ ·H ₂ O:GeO ₂ =7:1, ultrasonically stir in water for 30min, mix well and transfer to the lining of a 50mL polytetrafluoroethylene autoclave , put it into a stainless steel high-pressure reactor, raise it from room temperature to 180 °C at a rate of 20 °C/min, and keep it for 36 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge Dry to obtain a white powder.

The structure confirmation results and the apparent physical form, length and diameter of the white powder were the same as in Example 7.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are the same as in Example 7. The barium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Embodiment 9, the preparation of barium germanate nano material and its electrochemical performance test

Weigh according to the ratio of Ba(OH) ₂ ·8H ₂ O:GeO ₂ =5:1, ultrasonically stir in water for 30 minutes, mix evenly and transfer to a 100mL polytetrafluoroethylene autoclave lining, Put it into a stainless steel autoclave, raise the temperature from room temperature to 190 °C at a rate of 30 °C/min, and keep it for 48 hours, then naturally cool to room temperature, wash with deionized water three times, and dry after centrifugation. A white powder was obtained.

The structure confirmation results and the apparent physical form, length and diameter of the white powder were the same as in Example 7.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are the same as in Example 7. The barium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Example 10, preparation of magnesium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Mg(CH ₃ COO) ₂ ·4H ₂ O:GeO ₂ =1:1, ultrasonically stir in water for 30min, mix evenly and transfer to a 25mL polytetrafluoroethylene autoclave lining , put it into a stainless steel high-pressure reactor, raise the temperature from room temperature to 180 °C at a rate of 10 °C/min, and keep it for 48 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge Dry to obtain a white powder.

Characterization of magnesium germanate nanomaterials:

The structure was determined by powder X-ray diffractometer (Rigaku DmaxrB, CuK _α -ray), and the results are shown in FIG. 10 . As can be seen from the figure, there is no impurity peak in the spectrogram, indicating that the product has high purity and is the target product magnesium germanate.

Detect the thickness and diameter of the magnesium germanate obtained under the above-mentioned conditions with a Japanese electron scanning electron microscope (JEOL-6700F), and the result shows that the magnesium germanate obtained is a nano-sheet structure, with a diameter of 2-10 μm and a thickness of 20-80nm (see Figure 11).

Electrochemical performance characterization of magnesium germanate:

The magnesium germanate prepared in Example 10, acetylene black and polyvinylidene fluoride (binder) were mixed at a mass ratio of 70:20:10 to form a slurry, and evenly coated on the copper foil current collector to obtain a negative electrode Diaphragm. A metal lithium sheet was used as the positive electrode, a polypropylene microporous membrane (Celgard 2400) was used as the diaphragm, and 1mol/L LiPF ₆ (the solvent was a mixture of ethylene carbonate and dimethyl carbonate with a volume ratio of 1:1) was used as the electrolyte. A Swagelok-type mock battery was assembled in an argon-protected glove box.

The battery assembled above was subjected to a constant current charge and discharge test on an Arbin BT2000 charge and discharge tester. The charge and discharge rate was 100mA/g, and the charge and discharge voltage range was 0-3.0V. The magnesium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Example 11, preparation of magnesium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Mg(CH ₃ COO) ₂ ·4H ₂ O:GeO ₂ =2:1, ultrasonically stir in water for 30min, mix well and transfer to a 50mL polytetrafluoroethylene autoclave lining Put it into a stainless steel autoclave, raise the temperature from room temperature to 180 °C at a rate of 20 °C/min, and keep it for 24 hours, then naturally cool to room temperature, wash with deionized water three times, and centrifuge Dry to obtain a white powder.

The results of structural confirmation and the apparent physical form, length and diameter of the white powder were the same as in Example 10.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are the same as in Example 10. The barium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Example 12, preparation of magnesium germanate nanomaterial and its electrochemical performance test

Weigh according to the ratio of Mg(OH) ₂ :GeO ₂ =5:1, ultrasonically stir in water for 30min, mix evenly, transfer to a 100mL polytetrafluoroethylene autoclave liner, put it into In a stainless steel high-pressure reactor, the temperature was raised from room temperature to 200 °C at a rate of 30 °C/min, and kept for 24 hours, then naturally cooled to room temperature, washed with deionized water three times, centrifuged and dried to obtain a white powder.

The results of structural confirmation and the apparent physical form, length and diameter of the white powder were the same as in Example 10.

The positive electrode, negative electrode, electrolyte and battery assembly of the simulated battery are the same as in Example 10. The barium germanate prepared in this example and the test results of the simulated battery are listed in Table 1.

Table 1. Preparation conditions of alkaline earth metal germanate nanomaterials and simulated battery test results

According to the results in Table 1, it can be seen that the present invention uses soluble alkaline earth metal salts and germanium dioxide to conveniently prepare alkaline earth metal germanate nanomaterials through high-pressure hydrothermal reaction. As a new type of negative electrode material for lithium-ion batteries, it has greatly improved the problem of poor cycle performance of germanium-based negative electrode materials, showing a high specific capacity.

Claims (1)

1. a method of preparing germanic acid strontium nano material, comprises the steps: (the CH according to Sr ₃cOO) ₂1/2H ₂o:GeO ₂the ratio of the amount of substance of=1:4 takes, ultrasonic agitation 30min in water, transfers to after mixing in the autoclave liner of 25mL polytetrafluoroethylene, puts it in stainless steel autoclave, heating rate with 5 ℃/min, from room temperature, rise to 180 ℃, and keep 24 hours, then naturally cool to room temperature, with deionized water washing three times, dry after centrifugation, obtain white powder, be described germanic acid strontium nano material.

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