CN100341172C - Film lithium ion battery using stannous selenide film as anode material and its preparation method - Google Patents

Abstract

The invention belongs to the technical field of electrochemistry, and specifically relates to a lithium ion battery whose anode material adopts a nano-sized tin selenide (SnSe) film and a preparation method thereof. The thin film material is prepared by a pulsed laser deposition method, the particle size of the tin selenide (SnSe) thin film is 15-50nm, and the crystal structure belongs to an orthorhombic system. The specific capacity of the thin film electrode is 681mAh/g, and it shows good stability in the process of repeated charge and discharge. The thin film electrode material has good chemical stability, high specific capacity, simple preparation method and is suitable for thin film lithium ion batteries.

Description

Thin film lithium ion battery using tin selenide film as anode material and preparation method thereof

technical field

The invention belongs to the technical field of electrochemistry, and in particular relates to a thin-film lithium ion battery using a tin selenide thin film as an anode material and a preparation method thereof.

Background technique

With the miniaturization of microelectronic devices, it is urgent to develop a matching miniaturized and long-life power supply. Compared with other chemical batteries, the all-solid-state rechargeable thin-film lithium-ion battery has a large specific capacity, long charge and discharge life, and good safety performance. In order to make all-solid-state thin-film lithium-ion batteries have good performance, the key technology is to find anode and cathode materials with high specific capacity, long cycle life and less irreversible capacity loss.

Contents of the invention

The object of the present invention is to provide a kind of new thin film lithium ion battery, its anode material adopts tin selenide (SnSe) thin film, use this anode material can improve the performance of thin film lithium ion battery greatly.

In the thin-film lithium ion battery provided by the invention, the anode material adopts tin selenide (SnSe) thin film, and the thin film is composed of nano particles, the particle size is 15-50 nanometers, and the particle distribution is uniform. So far, there are no reports on any metal selenide materials used as anode materials for lithium-ion batteries.

The present invention firstly finds that tin selenide (SnSe) film material has good electrochemical properties, and the reversible specific capacity is 583mAh/g, higher than the reversible capacity of tin-based composite oxide 462mAh/g, and the reversible capacity loss after 40 cycles It is 30%, has better reversible cycle performance, therefore, can be used as lithium ion battery.

The preparation method of the present invention is mainly the preparation of the anode material tin selenide (SnSe) thin film, which adopts a reactive pulse laser deposition method. That is to say, the pulsed laser ablates the mixed target composed of tin powder and selenium powder to obtain the required thin film. The specific steps are as follows: grind and mix tin powder and selenium powder, wherein the amount of selenium powder is 1.3-1.6 times that of tin powder; after grinding, the mixture is pressed into a disc with a diameter of 10-15mm, which is used as a pulsed laser deposition The target uses a stainless steel sheet as the substrate, the distance between the substrate and the target is 35-42mm, and the substrate temperature is 400-450°C; the reaction chamber is pre-pumped to 1-2Pa, and argon gas is introduced, and the flow is controlled by a needle valve , and maintain the intracavity pressure at 2-8Pa; the 1064nm fundamental frequency generated by the Nd:YAG laser is tripled to obtain a 355nm laser, the laser beam is incident on the target after being focused by the lens, and the energy density is about 1.5-2.5J· cm ^-2 . The deposition time is determined by the film thickness requirements, generally 0.4-0.8h.

The remaining steps of the preparation method of the thin film lithium ion battery of the present invention are the same as the usual preparation methods.

The invention adopts the pulse laser to ablate the mixed target of tin powder and selenium powder to directly prepare the tin selenide film material. The material has the advantages of good chemical stability and the like. In the current reports on the preparation of tin selenide thin films by pulsed laser deposition, commercial tin selenide (SnSe) is used, and there is no report on the direct use of tin powder and selenium powder mixed targets.

In the present invention, the structure of tin selenide (SnSe) is determined by X-ray diffractometer (Bruker D8 Advance). The X-ray diffraction pattern shows that the tin selenide (SnSe) film obtained by pulsed laser reactive deposition has an orthorhombic structure and a small amount of metal tin exists. The measurement by scanning electron microscope (Philips XL30) shows that the tin selenide (SnSe) thin film prepared by pulsed laser reactive deposition is composed of nanoparticles with a diameter of 15-50 nanometers, and the particle distribution is uniform. The composition of the film was characterized by X-ray photoelectron spectroscopy (XPS). The results show that the composition is tin and selenium, where tin has two valence states, and the area of integrated Sn3d _5/2 and Se 3p _3/2 XPS spectra can estimate the composition of the film as Sn _0.1 (SnSe) _0.9 .

The electrochemical performance test of tin selenide (SnSe) film electrode among the present invention adopts the battery system that is made up of three electrodes, and wherein tin selenide (SnSe) film is used as working electrode, and high-purity lithium sheet is used as opposite electrode and respectively Reference electrode. The electrolyte solution is 1M LiPF ₆ +EC+DMC (V/V=1/1). Cell assembly was carried out in an argon-filled dry box. The charge and discharge experiments of the battery were carried out on the Land battery test system.

The tin selenide (SnSe) thin film electrode prepared on the stainless steel sheet by the pulse laser reactive deposition method in the invention has charge and discharge performance. After the tin selenide (SnSe) thin film electrode and metal lithium form the battery, the discharge plateau appears at 1.30V and 0.28V (relative to Li/Li ⁺ ). When the voltage range is 2.50-0.01V and the current density is 10μA/cm ² , the specific capacity of the thin film electrode is maintained at 400-681mAh/g. The above properties show that the tin selenide thin film electrode is a new type of anode material, which can be widely used in thin film lithium ion batteries.

Detailed ways

Example

The invention adopts a reactive pulse laser deposition method to prepare a tin selenide (SnSe) thin film, and the color is gray. During preparation, in the mixed target, the amount of selenium powder is 1.5 times that of tin powder, the diameter of the target is 13mm, clean stainless steel is used as the substrate, the distance between the substrate and the target is 38mm, and the temperature of the substrate is 400°C. Pre-evacuate the reaction chamber to 2Pa, pass in argon to maintain the pressure at 5Pa. The fundamental frequency generated by the Nd:YAG laser is tripled to generate 355nm pulsed laser. The laser repetition frequency is 10Hz and the pulse width is 10ns. The laser beam is focused by the lens and then incident on the mixed target of tin powder and selenium powder. The energy density is 2 J·cm ^-2 , and the deposition time is 0.5 hour.

The X-ray diffraction measurement shows that the deposited film is polycrystalline orthorhombic SnSe (SnSe) and a small amount of metallic tin. X-ray photoelectron spectroscopy showed peaks of Sn and Se, and the composition of the film was estimated to be Sn _0.1 (SnSe) _0.9 . According to the measurement of scanning electron microscope photos, the tin selenide (SnSe) thin film prepared by pulsed laser reactive deposition is composed of particles with a diameter of about 20 nanometers, and the particle distribution is uniform without pinholes.

The electrochemical performance test results of tin selenide (SnSe) thin film electrodes are as follows:

1. The tin selenide (SnSe) thin film electrode can be charged and discharged at a charge and discharge rate of 10μA/cm ² . In the voltage range of 0.01-2.5V, the first discharge capacity can reach 681mAh/g, the capacity decay is small after 40 cycles, and the reversible capacity loss is about 44%. The charge and discharge efficiency is 113%.

2. The cyclic voltammetry test of the tin selenide (SnSe) thin film electrode shows that in the first discharge process, four discharge potential peaks can be observed, respectively at 1.2V, 0.73V, 0.57V and 0.23V. After the second cycle, the peak at 1.2V shifted to 1.0V, the peak at 0.73V disappeared, the peak at 0.57V shifted to 0.50V, and the peak at 0.23V remained unchanged. Four peaks were observed at 0.50V, 0.65V, 0.80V and 1.9V during all charging processes.

3. After the electrochemical reaction of the tin selenide (SnSe) thin film electrode, the X-ray photoelectron spectroscopy test shows that the lithium-tin alloy exists in the thin film electrode of the electrochemical reaction.

4. After the electrochemical reaction of tin selenide (SnSe) thin film electrode and recharging, X-ray diffraction and X-ray photoelectron spectroscopy tests show that tin selenide (SnSe) is formed on the surface of the wave film, and some tin exists.

Therefore, nanoscale tin selenide (SnSe) thin film electrodes can be used as anode materials for lithium-ion batteries.

Claims (2)

1, a kind of film lithium ion battery is characterized in that anode adopts stannous selenide film, and this film is a polycrystalline structure, is made up of nano particle, and particle is of a size of the 15-50 nanometer, and distribution of particles is even.

2, a kind of preparation method of lithium ion battery as claimed in claim 1, the pulse laser reactive deposition processes is adopted in the preparation that it is characterized in that the anode material stannous selenide film, concrete steps are: with glass putty and selenium powder ground and mixed, wherein the amount of substance of selenium powder be glass putty 1.3-1.6 doubly; After the grinding mixture is pressed into the disk that diameter is 10-15mm, as the used target of pulsed laser deposition, adopts stainless steel substrates as substrate, the distance of substrate and target is 35-42mm, and substrate temperature is 400-450 ℃; Take out reaction chamber in advance to 1-2Pa, feed argon gas,, and keep that pressure is 2-8Pa in the chamber by its flow of a noticeable degree; The 1064nm fundamental frequency that is produced by the Nd:YAG laser obtains 355nm laser behind frequency tripling, laser beam is through inciding after the lens focus on the target, and energy density is 1.5-2.5Jcm ^-2