CN102299383B - Mist pyrolysis preparation method of all-solid-state film lithium battery - Google Patents

Abstract

The invention discloses a spray pyrolysis preparation method of an all-solid-state thin-film lithium battery. Double spray guns are used to simultaneously spray the precursor solutions of two layers at the junction of the electrode film layers. The solution flow rate increases gradually, creating a buffer layer between the two deposition layers. In the buffer layer, the content of the components of the two layers is gradually changed, and the content of the components in the lower layer gradually decreases, while the content of the components in the upper layer gradually increases. Its advantage is to form a tight combination of the upper and lower layers, increase the matching of the upper and lower layers, reduce stress and grain boundaries, improve the conductance of the interface, minimize the impact of the conductance of the interface on the overall performance of the battery, and improve the performance of the battery.

Description

A preparation method of spray pyrolysis for all-solid-state thin-film lithium battery

technical field

The invention relates to a preparation method of a lithium battery, in particular to a spray pyrolysis preparation method of an all-solid thin film lithium battery.

Background technique

The all-solid-state lithium-ion battery composed of inorganic solid electrolyte has the following advantages: it has higher specific energy than traditional nickel-cadmium and nickel-hydrogen batteries; the shape design of the battery is also more convenient and flexible, and can be prepared into almost any shape and size , can be directly integrated in the circuit; it has superior charge-discharge cycle performance, low self-discharge rate, and can overcome the problem of gradual failure of the liquid electrolyte lithium-ion battery due to the dissolution of the electrode active material in the electrolyte after a period of use [Z. R . Zhang, Z. L. Gong, and Y. Yang, J. Phys. Chem. B, 108, 2004, 17546.]; high safety, no gas generated during work, no leakage of electrolyte; stable performance , wide operating temperature range (-50 ~ 180 ℃), can be used in many extreme occasions.

In all-solid-state lithium-ion batteries, the mobility of carriers in the solid-state electrolyte is often much lower than the charge transfer on the electrode surface and the ion diffusion rate in the positive electrode material, which becomes the rate-controlling step in the entire electrode reaction kinetics. Inorganic solid-state electrolytes with high lithium-ion conductivity are the core key to constructing high-performance lithium-ion batteries. However, the bad thing is that the ionic conductivity of the inorganic solid electrolytes that are relatively stable in the air, have a wide electrochemical window, and relatively reasonable preparation costs are generally in the range of 10 ^-5 -10 ^-7 S·cm. ^-1 or so, it is difficult for a solid electrolyte sheet with a general thickness to meet the basic performance requirements of an all-solid-state lithium battery. Moreover, commercial or researched lithium-ion battery cathode materials such as lithium iron phosphate, lithium manganate, etc. have very low electronic conductivity and ionic conductivity, and the battery composed of simple solid electrode sheets greatly affects the overall performance of the battery. restrict.

The all-solid-state thin-film lithium-ion battery is a miniaturized all-solid-state lithium-ion battery. Its positive electrode material-solid electrolyte-negative electrode material is a thin film of several microns to tens of microns, which can overcome the low electronic conductivity and ion conductivity of the positive electrode material. And the low lithium ion conductivity of the solid electrolyte has an adverse effect on battery performance. All-solid-state thin-film lithium-ion batteries have a wide range of application prospects: including: miniature unmanned reconnaissance aircraft power supply (including camera device power supply), a variety of micro sensors, CMOS integrated circuits, smart cards (Smart Card), portable devices, etc., thus becoming Research and development of hot spots.

The current preparation of all-solid-state thin-film lithium batteries basically adopts radio frequency magnetron sputtering deposition, pulsed laser deposition, PECVD and other methods [Y. Iriyama, M. Yokoyama, C. Yada, et al. Electrochem. Solid State Lett., 2004 , 7(10): A340.]. These methods have huge equipment investment, complicated process and high cost. Spray pyrolysis is also an effective means of depositing thin films. A high-pressure carrier gas is used to atomize the precursor solution into small droplets of a few microns and bombard the surface of the heated substrate with these droplets at a fast speed. During this process, the droplets have undergone water evaporation, drying, heat Decompose, adhere to the surface of the substrate to form a thin layer of products, and gradually form a dense film with the continuous progress of atomization and pyrolysis. Spray pyrolysis does not require a vacuum environment, the process is simple, the investment in equipment is small, and it has the ability to prepare large-area films.

However, there are still many unsolved problems in the preparation of all-solid-state thin-film lithium batteries by this method:

1. Thin-film lithium batteries require at least three layers of thin films, namely positive electrode material-solid electrolyte-negative electrode material. An important factor affecting its overall performance is the tightness and matching degree of the interface between layers. In spray pyrolysis, the substrate temperature is usually not high and the kinetic energy brought by the carrier gas to the particles is limited (much less than magnetron sputtering or pulsed laser), resulting in a low degree of tightness and matching of the interface between layers, so the grain boundary resistance of the interface A higher value will seriously affect the overall performance of the battery.

2. There are few solid electrolyte materials suitable for spray pyrolysis preparation. At present, the solid electrolyte LiPON (nitrogen-doped lithium phosphate) with good performance can only be prepared by magnetron sputtering.

3. There are many process parameters that can be adjusted, such as carrier gas velocity, material flow rate, substrate temperature, distance between nozzle and substrate, etc. It is difficult to optimize the process conditions.

At present, research and development personnel have made some explorations on the preparation of all-solid-state thin-film batteries by spray pyrolysis, such as the Chinese invention patent application number 200910044488.7, such as the literature [P. FRAGNAND, R NAGARAJAN., D. VUJIC, J. Power Sources, 1995, 54: 362.], basically the positive or negative electrode sheet or electrolyte sheet of the whole thin-film battery is prepared by the traditional spray pyrolysis method, and it is difficult to overcome the interfacial conductivity between the electrode sheet and the electrolyte sheet, which affects the battery overall performance.

Contents of the invention

The technical problem to be solved by the present invention is to provide a spray pyrolysis preparation method of an all-solid-state thin-film lithium battery that minimizes the impact of interface conductance on the overall performance of the battery.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a spray pyrolysis preparation method of an all-solid-state thin-film lithium battery, which is characterized in that the specific steps are as follows: 1) Place the substrate on the surface of a heated working plate at a constant temperature of 200-500°C , the spray gun A is used to spray the precursor solution I, and the spray gun B is used to spray the precursor solution II; the vertical distance between the spray gun A and the surface of the heating work plate is 8-20cm, and the spray gun A forms an angle of 50-85 ^° with the surface of the heating work plate;

2) Apply carrier gas with a pressure of 60-300Kpa to spray gun A, and spray gun A to atomize and spray precursor solution I onto the substrate for 10-100 minutes; the spray flow rate is 1-10mL/min, followed by 1-2mL The speed of /min reduces the injection flow rate of the precursor solution I and continues to spray the precursor solution I until the injection is stopped;

3) At the same time, the vertical distance between the spray gun B and the surface of the heating work plate is 8-20cm, the spray gun B forms an intersection angle of 50-85 ^o with the surface of the heating work plate, and the carrier gas with a pressure of 60-300Kpa acts on the spray gun B, and the spray gun B atomizes and sprays the precursor solution II to the substrate, the flow rate of the precursor solution II increases at the same rate from zero until the injection flow rate is 1-10mL/min, and then the injection time lasts for 20-200 minutes; then decreases at a rate of 1-2mL/min The flow rate of precursor solution II and continue to spray precursor solution II; until the spraying is stopped;

4) Use the spray gun A to spray the precursor solution III. The vertical distance between the spray gun A and the surface of the heating work plate is ^8-20cm . Spray gun A atomizes and sprays precursor solution III onto the substrate, the flow rate of precursor solution III increases at the same rate from zero until the injection flow rate is 1-10mL/min, and then the injection time lasts for 10-100 minutes;

5) After spraying, after the surface of the heated working plate is cooled, put the processed substrate into a muffle furnace and keep the temperature at 500-700°C for 2-10 hours to produce an all-solid-state thin-film lithium battery.

Precursor solution I is: ammonium metavanadate with a concentration of 0.1-2 mol/L, ammonia water with a concentration of 0.05-0.3 mol/L, lithium acetate with a concentration of 0.1-2 mol/L, and an auxiliary compound with a concentration of 0.1-5 wt%. agent aqueous solution; the auxiliary agent can be one of ethylene glycol methyl ether, n-amyl alcohol, and polyvinyl alcohol PVA with an average molecular weight<5000.

The composition of the precursor solution II is: lanthanum nitrate with a concentration of 0.1-2mol/L, n-butyl titanate with a concentration of 0.1-2mol/L, acetic acid with a concentration of 0.1-1mol/L, and 0.1-2mol/L Lithium acetate, and an auxiliary agent aqueous solution with a mass percentage concentration of (0.1-5wt%); the auxiliary agent can be one of ethylene glycol methyl ether, n-pentanol, and polyvinyl alcohol PVA with an average molecular weight <5000.

The composition of precursor solution III is: lithium acetate with a concentration of 0.1-2mol/L, n-butyl titanate with a concentration of 0.1-2mol/L, acetic acid with a concentration of 0.1-1mol/L and 0.1-5wt% Aqueous solution of auxiliary agent; the auxiliary agent can be one of ethylene glycol methyl ether, n-amyl alcohol, and polyvinyl alcohol PVA with an average molecular weight <5000.

The substrate can be one of copper sheet, silicon sheet and nickel sheet.

    Compared with the prior art, the present invention has the advantage of adopting double spray guns to simultaneously spray the precursor solutions of two layers at the junction of the electrode film layers, the flow rate of the precursor solution in the lower layer gradually decreases, and the flow rate of the upper layer precursor solution gradually increases. A buffer layer is formed between the two deposited layers, and in the buffer layer, the contents of the components of the two layers are gradually changed, the contents of the components of the lower layer gradually become smaller, while the contents of the components of the upper layer gradually increase. In this way, the tight combination of the upper and lower layers is formed, the matching of the upper and lower layers is increased, the stress and grain boundaries are reduced, the conductance of the interface is improved, the influence of the conductance of the interface on the overall performance of the battery is minimized, and the performance of the battery is improved.

Description of drawings

Fig. 1 is a graph of discharge capacity decay of Example 2 on a battery performance tester at a rate of 0.5 times charge and discharge for 100 cycles.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Example 1: Place the copper substrate at a constant temperature of 250°C to heat the surface of the working plate, spray gun A is used to spray the precursor solution I: ammonium metavanadate NH ₄ VO ₃ with a concentration of 0.3 mol/L, and a concentration of 0.08 mol/L ammonia water NH ₃ ·H ₂ O, lithium acetate Li(CH ₃ COO) with a concentration of 0.1 mol/L, and an aqueous solution of ethylene glycol methyl ether with a concentration of 0.2 wt%. Spray gun B is used to spray precursor solution II: lanthanum nitrate La(NO ₃ ) ₃ with a concentration of 0.2mol/L, n-butyl titanate Ti(OC ₄ H ₉ ) ₄ with a concentration of 0.4mol/L, and a concentration of 0.2mol/L L of acetic acid CH ₃ COOH, lithium acetate Li(CH ₃ COO) with a concentration of 0.18 mol/L, and an aqueous solution of n-pentanol with a concentration of 0.1 wt%. The vertical distance between the spray gun A and the surface of the heating work plate is 10cm, the intersection angle between the spray gun A and the surface of the heating work plate ^{is 55o} , and the carrier gas with a pressure of 60Kpa is applied to the spray gun A, and the spray gun A atomizes and sprays the precursor solution I onto the copper substrate, continuously Spray for 30 minutes, and the injection flow rate is 3mL/min; then reduce the flow rate of precursor solution I at a rate of 1mL/min and continue to spray precursor solution I until the injection is stopped;

At the same time, the vertical distance between the spray gun B and the surface of the heating work plate is 10cm, the spray gun B and the surface of the heating work plate form an intersection angle of 55 ^° , and the carrier gas with a pressure of 60Kpa acts on the spray gun B, and the spray gun B atomizes and sprays the precursor solution II onto the copper substrate , the flow rate of precursor solution II was increased from zero at a rate of 1 mL/min until the injection flow rate was 3 mL/min, and then the injection time lasted for 50 minutes. Then reduce the flow rate of the precursor solution II at a rate of 1 mL/min and continue to spray the precursor solution II; until the spraying is stopped;

Spray gun A sprays precursor solution III: Lithium acetate Li(CH ₃ COO) at a concentration of 0.4mol/L, n-butyl titanate Ti(OC ₄ H ₉ ) ₄ at a concentration of 0.3mol/L at a concentration of 0.5mol/L An aqueous solution of acetic acid CH ₃ COOH and polyvinyl alcohol PVA (average molecular weight <5000) with a concentration of 0.2 wt%. The vertical distance between the spray gun A and the surface of the heating work plate is 10m, the intersection angle between the spray gun A and the surface of the heating work plate is 55 ^° , and the carrier gas with a pressure of 60Kpa is applied to the spray gun A, and the spray gun A atomizes and sprays the precursor solution III onto the copper substrate, and the precursor solution The flow rate of III starts from zero and increases at a rate of 1mL/min until the injection flow rate is 3mL/min. The spray time was then continued for 30 minutes. After spraying, after the surface of the heated working plate is cooled, the processed substrate is placed in a muffle furnace at a temperature of 500°C for 3 hours to obtain an all-solid-state thin-film lithium battery.

Example 2: Place the silicon wafer substrate at a constant temperature of 350°C to heat the surface of the working plate, and the spray gun A is used to spray the precursor solution I: ammonium metavanadate NH ₄ VO ₃ with a concentration of 1.0 mol/L and a concentration of 0.15 mol/L ammonia water NH ₃ ·H ₂ O, lithium acetate Li(CH ₃ COO) with a concentration of 0.3 mol/L, and an aqueous solution of ethylene glycol methyl ether with a concentration of 2 wt%. Spray gun B sprays precursor solution II: lanthanum nitrate La(NO ₃ ) ₃ with a concentration of 0.5mol/L, n-butyl titanate Ti(OC ₄ H ₉ ) ₄ with a concentration of 1.0mol/L, and 0.5mol/L An aqueous solution of acetic acid CH ₃ COOH, lithium acetate Li(CH ₃ COO) with a concentration of 0.52 mol/L and polyvinyl alcohol PVA (average molecular weight <5000) with a concentration of 2.2 wt%. The vertical distance between the spray gun A and the surface of the heating work plate is 15cm, and the intersection angle between the spray gun A and the surface of the heating work plate is ^70o , and the carrier gas with a pressure of 150Kpa is applied to the spray gun A, and the spray gun A atomizes and sprays the precursor solution I onto the substrate, continuously spraying for 50 Minutes, the injection flow rate is 6mL/min. Then reduce the flow rate of the precursor solution I and continue to spray the precursor solution I at a speed of 1.5mL/min until the injection stops;

At the same time, the vertical distance between the spray gun B and the surface of the heating work plate is 15cm, and the intersection angle between the spray gun B and the surface of the heating work plate is ^70o , and the carrier gas with a pressure of 150Kpa acts on the spray gun B, and the spray gun B atomizes and sprays the precursor solution II onto the substrate, and the precursor solution II The flow rate increases from zero at a rate of 1.5mL/min until the injection flow rate is 6mL/min, and then the injection time lasts for 100 minutes. Then reduce the flow rate of the precursor solution II at a rate of 1.5mL/min and continue to spray the precursor solution II until the spraying is stopped;

Spray gun A sprays precursor solution III: lithium acetate Li(CH ₃ COO) with a concentration of 1.0mol/L, n-butyl titanate Ti(OC ₄ H ₉ ) ₄ with a concentration of 1.25mol/L, and a concentration of 0.45mol/L An aqueous solution of acetic acid CH ₃ COOH and a mass percentage concentration of 1.9 wt% n-pentanol. Spray gun A is 15m away from the surface of the heating plate, and the angle between spray gun A and the surface of the heating plate is ^70o . Carrier gas with a pressure of 150Kpa is applied to spray gun A. Spray gun A atomizes and sprays precursor solution III onto the substrate. Precursor solution III The flow rate increases from zero at a rate of 1.5mL/min until the injection flow rate is 6mL/min. The spray time was then continued for 55 minutes. After spraying, after the surface of the heated working plate is cooled, the substrate is placed in a muffle furnace and kept at 700°C for 10 hours to obtain an all-solid-state thin-film lithium battery.

As shown in Figure 1, Example 2 is charged and discharged at a high rate of 0.5 times on a battery performance tester produced by Wuhan Landian Electronics Co., Ltd. for 100 cycles of discharge capacity decay. It can be seen from the figure that in the first 6 cycles, the discharge capacity was slightly lower due to the need to activate the electrode active material, but it quickly reached a stable capacity of 130mAh·g, and there was almost no decay within 100 cycles.

Example 3: Place the nickel sheet substrate at a constant temperature of 500°C to heat the surface of the working plate, and the spray gun A is used to spray the flooding solution I: ammonium metavanadate NH ₄ VO ₃ with a concentration of 2.0mol/L and a concentration of 0.28mol/L ammonia water NH ₃ ·H ₂ O, lithium acetate Li(CH ₃ COO) with a concentration of 0.7 mol/L, and an aqueous solution of n-pentanol with a concentration of 4.5 wt%. Spray gun B sprays precursor solution II: lanthanum nitrate La(NO ₃ ) ₃ with a concentration of 1.0 mol/L, n-butyl titanate Ti(OC ₄ H ₉ ) ₄ with a concentration of 2.0 mol/L, and a concentration of 0.9 mol/L acetic acid CH ₃ COOH, lithium acetate Li(CH ₃ COO) with a concentration of 0.95 mol/L, and an aqueous solution of ethylene glycol methyl ether with a concentration of 4.7 wt%. Spray gun A is 19cm away from the surface of the heating plate, and the angle between spray gun A and the surface of the heating plate is 80 ^° . Carrier gas with a pressure of 300Kpa is applied to spray gun A. Spray gun A atomizes and sprays precursor solution I onto the substrate for 90° Minutes, the injection flow rate is 10mL/min, then reduce the flow rate of the precursor solution I at a speed of 2mL/min and continue to spray the precursor solution I until the injection is stopped;

At the same time, the vertical distance between the spray gun B and the surface of the heating work plate is 19cm, and the angle between the spray gun B and the surface of the heating work plate ^{is 80o} . The flow rate of solution II was increased from zero at a rate of 2 mL/min until the injection flow rate was 10 mL/min, and then the injection time lasted for 180 minutes. Then reduce the flow rate of the precursor solution II at a rate of 2mL/min and continue to spray the precursor solution II until the spraying is stopped;

Spray gun A sprays precursor solution III: lithium acetate Li(CH ₃ COO) with a concentration of 1.6 mol/L, n-butyl titanate Ti(OC ₄ H ₉ ) ₄ with a concentration of 2.0 mol/L, and a concentration of 0.92 mol/L An aqueous solution of acetic acid CH ₃ COOH and 4.3 wt% ethylene glycol methyl ether. The vertical distance between the spray gun A and the surface of the heating work plate is 19m, and the intersection angle between the spray gun A and the heating work plate is ^80o , and the carrier gas with a pressure of 300Kpa acts on the spray gun A, and the spray gun A atomizes and sprays the precursor solution III onto the substrate. The flow rate increases from zero at a rate of 2 mL/min until the injection flow rate reaches 10 mL/min, and then the injection time lasts for 90 minutes. After spraying, after the surface of the heated working plate is cooled, the substrate is placed in a muffle furnace and kept at 600°C for 6 hours to obtain an all-solid-state thin-film lithium battery.

Claims (2)

1. A method for preparing an all-solid-state thin-film lithium battery by spray pyrolysis, which is characterized in that the specific steps are as follows: 1) Place the substrate on the surface of a heated working plate at a constant temperature of 200-500°C, and the spray gun A is used to spray the precursor solution I, and the spray gun B is used to spray the precursor solution II; the vertical distance between spray gun A and the surface of the heating work plate is 8-20cm, and the intersection angle between spray gun A and the surface of the heating work plate is 50-85 ^o ; 2) Apply carrier gas with a pressure of 60-300Kpa to spray gun A, and spray gun A to atomize and spray precursor solution I onto the substrate for 10-100 minutes; the spray flow rate is 1-10mL/min, followed by 1-2mL The speed of /min reduces the injection flow rate of the precursor solution I and continues to spray the precursor solution I until the injection is stopped; 3) At the same time, the vertical distance between the spray gun B and the surface of the heating work plate is 8-20cm, the spray gun B forms an intersection angle of 50-85 ^o with the surface of the heating work plate, and the carrier gas with a pressure of 60-300Kpa acts on the spray gun B, and the spray gun B atomizes and sprays the precursor solution II to the substrate, the flow rate of the precursor solution II increases at the same rate from zero until the injection flow rate is 1-10mL/min, and then the injection time lasts for 20-200 minutes; then decreases at a rate of 1-2mL/min The flow rate of precursor solution II and continue to spray precursor solution II; until the spraying is stopped; 4) Use the spray gun A to spray the precursor solution III. The vertical distance between the spray gun A and the surface of the heating work plate is ^8-20cm . Spray gun A atomizes and sprays precursor solution III onto the substrate, the flow rate of precursor solution III increases at the same rate from zero until the injection flow rate is 1-10mL/min, and then the injection time lasts for 10-100 minutes; 5) After spraying, after the surface of the heated working plate is cooled, put the processed substrate into the muffle furnace and keep the temperature at 500-700°C for 2-10 hours to obtain an all-solid-state thin-film lithium battery; Precursor solution I is: ammonium metavanadate with a concentration of 0.1-2 mol/L, ammonia water with a concentration of 0.05-0.3 mol/L, lithium acetate with a concentration of 0.1-2 mol/L, and an auxiliary compound with a concentration of 0.1-5 wt%. agent aqueous solution; the auxiliary agent is one of ethylene glycol methyl ether, n-amyl alcohol, and polyvinyl alcohol with an average molecular weight<5000; The composition of precursor solution II is: lanthanum nitrate with a concentration of 0.1-2mol/L, n-butyl titanate with a concentration of 0.1-2mol/L, acetic acid with a concentration of 0.1-1mol/L and a concentration of 0.1-2mol/L Lithium acetate, and the aqueous solution of auxiliary agent that mass percent concentration is (0.1-5wt%); This auxiliary agent is a kind of in the polyvinyl alcohol of ethylene glycol methyl ether, n-amyl alcohol, average molecular weight＜5000; The composition of precursor solution III is: lithium acetate with a concentration of 0.1-2mol/L, n-butyl titanate with a concentration of 0.1-2mol/L, acetic acid with a concentration of 0.1-1mol/L and 0.1-5wt% Aqueous solution of auxiliary agent; the auxiliary agent is one of ethylene glycol methyl ether, n-amyl alcohol, and polyvinyl alcohol with an average molecular weight <5000. 2. The spray pyrolysis preparation method of the all-solid-state thin-film lithium battery according to claim 1, wherein the substrate is one of a copper sheet, a silicon sheet, and a nickel sheet. the

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