CN105186043B - All solid state LiMn2O4‑Li4Ti5O12Battery and preparation method thereof - Google Patents

Abstract

The invention discloses a method for preparing an all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery, comprising the following steps: uniformly mixing LiMn ₂ O ₄ , conductive agent, solid electrolyte, and aluminum powder, and pressing into tablets to form a prefabricated positive electrode body; mix Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte, and aluminum powder evenly, and press to form a negative electrode preform; place the two positive electrode preforms or negative electrode preforms on both sides of the current collector aluminum foil and heat Bond the positive electrode or negative electrode prefabricated body with the current collector aluminum foil to form the positive electrode sheet and the negative electrode sheet respectively; form a solid electrolyte layer on the surface of the positive electrode sheet or the negative electrode sheet; stack the positive electrode sheet and the negative electrode sheet alternately to make the solid electrolyte layer Clamped between the positive electrode sheet and the negative electrode sheet, forming a battery preform after hot pressing; and removing the moisture in the battery preform, and sealing it with an aluminum-plastic film to obtain the all-solid LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ batteries. The present invention also provides an all-solid LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery obtained by the above method.

Description

All-solid LiMn2O4-Li4Ti5O12 battery and its preparation method

technical field

The invention relates to an all-solid LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery and a preparation method thereof.

Background technique

Most of the electrolytes currently used in lithium batteries contain volatile and flammable organic solvents. In order to manufacture batteries with higher output voltage, higher energy density and larger scale, it is necessary to use electrolytes containing a large amount of organic solvents. However, the organic electrolyte in the battery causes serious fire and electrolyte leakage occurs from time to time. The most effective way to overcome these safety issues and create a reliable battery is to replace the flammable liquid electrolyte with a nonflammable solid electrolyte. Compared with traditional liquid electrolyte batteries, all-solid-state lithium batteries not only have higher energy, but also avoid the corrosion of containers by liquid electrolytes such as acid and alkali, and have the advantages of no leakage, long storage life, and easy miniaturization. The wide operating temperature range extends the application range of lithium batteries to various special working environments such as electric vehicles, energy storage, aerospace, biology, and the human body. It will increasingly affect and change people's lives.

In summary, the development and utilization of all-solid-state lithium batteries has great practical significance.

Contents of the invention

The invention provides a method for preparing an all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery, comprising the following steps:

Mix LiMn ₂ O ₄ , conductive agent, solid electrolyte, and aluminum powder evenly, and hot press to form a positive electrode preform;

Mix Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte, and aluminum powder evenly, and hot press to form a negative electrode preform;

Place the two positive electrode preforms and negative electrode preforms on both sides of the current collector aluminum foil and heat press to form the positive electrode sheet and the negative electrode sheet respectively;

forming a solid electrolyte layer on at least one surface of the positive electrode sheet or the negative electrode sheet;

alternately stacking the positive electrode sheet and the negative electrode sheet, so that the solid electrolyte layer forms a sandwich structure with the positive electrode sheet and the negative electrode sheet, and forms a battery prefabricated body after hot pressing; and

The moisture in the battery prefabricated body was removed, and the aluminum-plastic film was sealed to obtain the all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery.

Further, the mass ratio of LiMn ₂ O ₄ , conductive agent, solid electrolyte and aluminum powder in the positive electrode preform is 10:0.1~1.0:0.5~1.5:0.5~1.5.

Further, the mass ratio of LiMn ₂ O ₄ , conductive agent, solid electrolyte and aluminum powder in the positive electrode preform is 10:0.3~0.7:0.8~1.2:0.8~1.2.

Further, the mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and aluminum powder in the negative electrode preform is 10:0.1~1.0:0.5~1.5:0.5~1.5.

Further, the mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and aluminum powder in the negative electrode preform is 10:0.3~0.7:0.8~1.2:0.8~1.2.

Further, the solid electrolyte layer is formed by magnetron sputtering.

Further, the positive electrode preform and the negative electrode preform are heated to 660° C. to 680° C. to melt the aluminum powder to form the positive electrode sheet and the negative electrode sheet respectively.

The present invention also provides an all-solid LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery, comprising:

The positive electrode sheet includes uniformly mixed LiMn ₂ O ₄ , conductive agent, solid electrolyte and metal aluminum, wherein the metal aluminum is bonded between LiMn ₂ O ₄ , conductive agent and solid electrolyte;

Negative electrode sheet, including uniformly mixed Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and metal aluminum, wherein the metal aluminum is bonded between Li ₄ Ti ₅ O ₁₂ , conductive agent and solid electrolyte;

The interlayer is a solid electrolyte layer between the positive electrode sheet and the negative electrode sheet.

Further, the mass ratio of LiMn ₂ O ₄ , conductive agent, solid electrolyte and metal aluminum in the positive electrode sheet is 10:0.1~1.0:0.5~1.5:0.5~1.5.

Further, the mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and aluminum powder in the negative electrode sheet is 10:0.1~1.0:0.5~1.5:0.5~1.5.

The all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery provided by the present invention not only has high energy, but also can make the above-mentioned battery have a good cycle time by using metal aluminum as the binder of the positive electrode sheet and the negative electrode sheet. performance and safety features. In addition, the preparation method of the present invention also has the characteristics of simple manufacturing process and easy industrial application.

Description of drawings

Fig. 1 is a flow chart for preparing an all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery provided by an embodiment of the present invention.

FIG. 2 is a cycle test graph of the all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery obtained in Example 1.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, only some structures related to the present invention are shown in the drawings but not all structures.

Please refer to Figure 1, a method for preparing an all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery, including the following steps:

S1, mix LiMn ₂ O ₄ , conductive agent, solid electrolyte, and aluminum powder evenly, and hot press to form a positive electrode preform;

S2, mixing Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte, and aluminum powder evenly, and hot pressing to form a negative electrode preform;

S3, placing the two positive electrode preforms and negative electrode preforms on both sides of the current collector aluminum foil and hot pressing to form the positive electrode sheet and the negative electrode sheet respectively;

S4, forming a solid electrolyte layer on at least one surface of the positive electrode sheet or the negative electrode sheet;

S5, stacking the positive electrode sheet and the negative electrode sheet alternately, so that the solid electrolyte layer is located between the positive electrode sheet and the negative electrode sheet, forming a battery prefabricated body after hot pressing; and

S6, removing the moisture in the battery preform, and sealing it with an aluminum-plastic film to obtain the all-solid LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery.

In step S1, the mass ratio of LiMn ₂ O ₄ , conductive agent, solid electrolyte and aluminum powder in the positive electrode preform is 10:0.1~1.0:0.5~1.5:0.5~1.5; preferably, the positive electrode preform The mass ratio of LiMn ₂ O ₄ , conductive agent, solid electrolyte and aluminum powder is 10:0.3~0.7:0.8~1.2:0.8~1.2; more preferably, LiMn ₂ O ₄ , conductive agent, The mass ratio of the solid electrolyte to the aluminum powder is 10:0.4~0.6:0.9~1.1:0.9~1.1. The purpose of adding aluminum powder to the positive electrode preform is to serve as a binder for the solid electrolyte of LiMn ₂ O ₄ and conductive agent. The solid electrolyte can be a lithium ion conductor, such as β-Al ₂ O ₃ , LiPON, Li ₂ SP ₂ S ₅ glass, Li ₁₀ GeP ₂ S ₁₂ , NASICON, LISICON, Li _3x La _1-3x of perovskite structure TiO ₃ (LLT, 0<x<0.16) and other solid electrolyte systems. The conductive agent may be activated carbon, conductive carbon black, carbon nanotubes, graphene or other types of conductive additives.

In step S2, the mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and aluminum powder in the negative electrode preform is 10:0.1~1.0:0.5~1.5:0.5~1.5; preferably, the negative electrode The mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and aluminum powder in the preform is 10:0.3~0.7:0.8~1.2:0.8~1.2; more preferably, the Li ₄ Ti ₅ in the negative electrode preform The mass ratio of O ₁₂ , conductive agent, solid electrolyte and aluminum powder is 10:0.4~0.6:0.9~1.1:0.9~1.1. The purpose of adding aluminum powder to the negative electrode preform is to serve as a binder for the solid electrolyte of Li ₄ Ti ₅ O ₁₂ and the conductive agent, and to improve the conductivity of the entire pole piece.

In step S3, preferably, heating is performed in a vacuum atmosphere or an inert gas atmosphere, so as to prevent oxidation. In addition, the heating temperature may be greater than or equal to the melting point of the aluminum powder, that is, greater than or equal to 660°C. In order not to damage the structure of the solid electrolyte, Li ₄ Ti ₅ O ₁₂ and LiMn ₂ O ₄ , the heating temperature is 660° C. to 680° C. Preferably, the heating temperature is 660°C to 670°C. More preferably, the heating temperature is 660°C to 665°C. Since the heating temperature is higher than the melting point of the aluminum powder, the aluminum powder of the positive electrode preform will melt and bond between the LiMn ₂ O ₄ and the solid electrolyte of the conductive agent. It can be understood that the aluminum powder in the negative electrode preform will also be melted, so as to bond between Li ₄ Ti ₅ O ₁₂ and the solid electrolyte of the conductive agent. Further, the heating time is preferably 10 minutes to 60 minutes. Furthermore, an annealing step is included, the annealing temperature is 400° C. to 600° C., and the annealing time is 1 hour to 2 hours. Experiments have proved that more stable positive and negative electrodes can be obtained through annealing treatment. More preferably, the annealing temperature is 500°C to 600°C.

In step S4, a solid electrolyte layer may be formed on at least one surface of the positive electrode sheet or the negative electrode sheet. The solid electrolyte layer may be formed by a magnetron sputtering method or other methods. The thickness of the solid electrolyte layer can be selected according to actual needs, and is generally 1 micron to 10 microns. Preferably, the solid electrolyte layer has a thickness of 2 microns to 5 microns. More preferably, the solid electrolyte layer has a thickness of 2 microns to 4 microns, so that the charging and discharging performance of the battery can be significantly improved.

In step S5, the hot pressing temperature is 600°C-660°C.

In step S6, the moisture in the battery preform can be removed by vacuum drying, heat drying or other methods, and sealed with an aluminum-plastic film to obtain the all-solid LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery.

The present invention also provides an all-solid LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery, comprising:

The positive electrode sheet includes uniformly mixed LiMn ₂ O ₄ , conductive agent, solid electrolyte and metal aluminum, wherein the metal aluminum is bonded between LiMn ₂ O ₄ , conductive agent and solid electrolyte;

Negative electrode sheet, including uniformly mixed Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and metal aluminum, wherein the metal aluminum is bonded between Li ₄ Ti ₅ O ₁₂ , conductive agent and solid electrolyte;

sandwiching a solid electrolyte layer between said positive and negative electrode sheets;

a first current collector, disposed on a side of the positive electrode sheet away from the solid electrolyte layer; and

The second current collector is arranged on the side of the negative electrode sheet away from the solid electrolyte layer.

The mass ratio of LiMn ₂ O ₄ , conductive agent, solid electrolyte and metal aluminum in the positive electrode sheet is 10:0.1-1.0:0.5-1.5:0.5-1.5. Preferably, the mass ratio of LiMn ₂ O ₄ , conductive agent, solid electrolyte and aluminum powder in the positive electrode sheet is 10:0.3~0.7:0.8~1.2:0.8~1.2; more preferably, the LiMn ₂ in the positive electrode sheet The mass ratio of O ₄ , conductive agent, solid electrolyte and aluminum powder is 10:0.4~0.6:0.9~1.1:0.9~1.1.

Further, the mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and metal aluminum in the negative electrode sheet is 10:0.1~1.0:0.5~1.5:0.5~1.5. Preferably, the mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and aluminum powder in the negative electrode sheet is 10:0.3~0.7:0.8~1.2:0.8~1.2; more preferably, the negative electrode sheet The mass ratio of Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and aluminum powder is 10:0.4~0.6:0.9~1.1:0.9~1.1. The first current collector and the second current collector are preferably aluminum foils, so as to form good contact with the positive electrode sheet and the negative electrode sheet.

Example 1:

Weigh 1g LiMn ₂ O ₄ , 0.05g conductive carbon black, 0.1g aluminum powder, 0.1g Li _3x La _1-3x TiO ₃ with perovskite structure and mix evenly. Positive electrode sheet: Weigh 1g Li ₄ Ti ₅ O ₁₂ , 0.05g conductive carbon black, 0.1g aluminum powder, 0.1g Li _3x La _1-3x TiO ₃ with perovskite structure and mix evenly, and press the tablet at 660°C under an inert atmosphere Heat treatment to form a negative electrode sheet; sputter a Li _3x La _1-3x TiO ₃ film with a perovskite structure with a thickness of about 2 microns on one surface of the positive electrode sheet, then place the negative electrode on the positive electrode sheet and place it on the back of the positive and negative electrodes. Aluminum foil of appropriate size is placed on it, and the positive and negative electrodes are bonded with the solid electrolyte under moderate pressure, and the aluminum foil and the positive and negative electrodes are bonded together to form an electrode pair; after removing moisture, seal it with an aluminum-plastic composite film to obtain a battery. Please refer to Figure 2, after 210 charge-discharge cycles, the battery capacity has no attenuation.

Example 2:

It is basically the same as in Example 1, except that both the positive electrode preform and the negative electrode preform contain 0.15 g of aluminum powder. Experiments have proved that the battery capacity has no attenuation after 200 charge-discharge cycles.

Example 3:

It is basically the same as Example 1, except that both the positive electrode preform and the negative electrode preform contain 0.05 g of aluminum powder. Experiments have proved that the battery capacity has no attenuation after 180 charge and discharge cycles.

Example 4:

It is basically the same as Example 1, except that the heat treatment temperature of the positive electrode preform and the negative electrode preform is 670°C. Experiments have proved that the battery capacity has no attenuation after 200 charge-discharge cycles.

Example 5:

It is basically the same as Example 1, except that the heat treatment temperature of the positive electrode preform and the negative electrode preform is 680°C. Experiments have proved that the battery capacity has no attenuation after 180 charge and discharge cycles.

Embodiment 6:

It is basically the same as Example 1, except that both the positive electrode preform and the negative electrode preform contain 0.15 g of Li _3x La _1-3x TiO ₃ with a perovskite structure. Experiments have proved that the battery capacity has no attenuation after 200 charge-discharge cycles.

Embodiment 7:

It is basically the same as in Example 1, except that both the positive electrode preform and the negative electrode preform contain 0.05 g of conductive carbon black. Experiments have proved that the battery capacity has no attenuation after 200 charge-discharge cycles.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

Claims (7)

1. A method for preparing an all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery, characterized in that it comprises the following steps: Mix LiMn ₂ O ₄ , conductive agent, solid electrolyte, and aluminum powder evenly, and hot press to form a positive electrode preform; Mix Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte, and aluminum powder evenly, and hot press to form a negative electrode preform; In a vacuum atmosphere or an inert gas atmosphere, heat the positive electrode preform and the negative electrode preform and combine them with the current collector aluminum foil to form the positive electrode sheet and the negative electrode sheet respectively, wherein the heating temperature is 660°C-680°C, and the heating time is 10-50min. Perform annealing treatment after heating, the annealing temperature is 400-600°C, and the annealing time is 1-2h; forming a solid electrolyte layer on at least one surface of the positive electrode sheet or the negative electrode sheet; Alternately stacking the positive electrode sheet and the negative electrode sheet, sandwiching the solid electrolyte layer between the positive electrode sheet and the negative electrode sheet, and hot pressing to form a battery prefabricated body; and The moisture in the battery prefabricated body was removed, and the aluminum-plastic film was sealed to obtain the all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery. 2. The preparation method of the all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery according to claim 1, characterized in that, in the positive electrode preform, LiMn ₂ O ₄ , conductive agent, solid electrolyte and aluminum powder The mass ratio is 10:0.1～1.0:0.5～1.5:0.5～1.5. 3. The preparation method of the all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery according to claim 2, characterized in that, in the positive electrode preform, LiMn ₂ O ₄ , conductive agent, solid electrolyte and aluminum powder The mass ratio is 10:0.3～0.7:0.8～1.2:0.8～1.2. 4. The preparation method of the all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery according to claim 1, characterized in that, in the negative electrode preform, Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and The mass ratio of the aluminum powder is 10:0.1-1.0:0.5-1.5:0.5-1.5. 5. The preparation method of the all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery according to claim 4, characterized in that, in the negative electrode preform, Li ₄ Ti ₅ O ₁₂ , conductive agent, solid electrolyte and The mass ratio of the aluminum powder is 10:0.3-0.7:0.8-1.2:0.8-1.2. 6. The method for preparing an all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery according to claim 1, wherein the solid electrolyte layer is formed by magnetron sputtering. 7. An all-solid-state LiMn ₂ O ₄ -Li ₄ Ti ₅ O ₁₂ battery, characterized in that it is prepared according to the preparation method described in any one of claims 1-6.