SI21155A - Material based on single-layer nanotube bundles of transient metals dichalcogenides and electronic conductor for the use in lithium batteries and accumulators - Google Patents

Abstract

The invention deals with the manufacture and application of electronic material based on single-layer nanotubes of dichalcogenides of transient metals and electronic conductor for lithium-ion batteries and accumulators. The material based on single-layer nanotubes of dichalcogenide transient metals and electronic conductor provide the integration of lithium into lithium-diaphragm batteries and the integration of lithium to lithium-ion batteries. The quantity of the integrated lithium in the material based on single-layer nanotube bundles of transient metals dichalcogenides and electronic conductor depends on the share of the active material and on the preparation of these, amounting to 3.2 mol (average value 2.3 mol) lithium per mol of transient metal chalcogenides. The average voltage of making lithium from active material based on single-layer MoS2 nanotube bundles and electronic conductor, is 1.1 V measured against the semi-element Li/Li+.

Description

Material based on bundles of single-layer transition metal dichalcogenide nanotubes and electronic conductor for use in lithium batteries and accumulators

Subject of the invention, the field of technology to which the invention belongs

The object of the invention is the manufacture and use of an active electrode material based on bundles of single-layer transition metal dichalcogenide nanotubes and an electronic conductor in lithium-ion batteries and accumulators. The invention falls within the field of chemical technology, more specifically, of materials into which lithium ions can be incorporated or constructed and are suitable for use in lithium ion batteries. The invention relates to the manufacture and use of material from bundles of single-walled transition metal dichalcogenide nanotubes and an electronic conductor for the active material in lithium-ion batteries and accumulators.

The state of the art

Lithium ion batteries operate on the basis of the installation and construction of Li ⁺ ions. When charging the battery, Li ⁺ ions are embedded in the negative electrode and built from the positive electrode. Reversing the potential at the electrodes (or discharge via the current consumer) results in a reverse process (AR Armstrong et al., Nature, vol. 381, 499 (1996)), so the electrodes are made of materials that allow the incorporation / construction of Li ⁺ ions . Much research has been done on oxides and sulfides as active materials for electrodes (H. Park et al., J. Electrochem. Soc., 142, 1068 (1995)).

In the lithium ion battery subclasses, which reach a current density of 1 pAcrri to 1 mAcm ² , layered crystals of transition metal dichalcogenides are also commonly used as the active cathode material. Particles of layered crystals are large usually from 1-100 pm.

Lithium is incorporated into individual crystal layers of transition metal dichalcogenides in transition metals (C.A. Vincent and B. Scrosati in Modern batteries, Arnold, London, 1997).

The intercalation of alkali metals into layered crystals of transition metal dichalcogenides was first described by Rudorff (Chimia 19, 489 (1965)). M0S2, T1S2, and WS ₂ layered crystals and mixtures of these layered crystals with other composite materials are most commonly used (Anderman et al .; Cathodic electrode; U.S. Patent # 4,735,875). Lithium is incorporated into the crystalline layers of transition metal chalcogenide crystals in the form of solvated Li ⁺ cation (JO Besenhard et al. Z. Naturforsh. 3lb 907 (1976)). One of the major limitations in the use of layered dichalcogenide crystals for the active material is also the decomposition of the electrolyte (K.Kumai et al., J. Power Sources 70, 235 (1998)).

The incorporation of lithium into multilayer carbon nanotubes (MWNTs), where lithium is embedded in the wall of a carbon nanotube (E. Frackowiak et al .; Carbon 37, 61-69 (1999)), or into the interstices of bundles of carbon single-layer nanotubes, is also known and described. (SWNT) (Zhou OZ: Nano-based High Energy Material and Method; U.S. Patent No. 6,280,697)). An example of using intercalated fullerene-like inorganic structures as an active material is also described. (Homyonfer et al.; Method for the preparation of metal intercalated fuller ene'like chalcogenides; U.S. Patent No. 6,217,843).

Japanese, European and US patent databases and publications have been reviewed since 1991, but so far the use of single-layer transition metal dichalcogenide nanotube bundles as active material in lithium ion batteries has not been described.

Installation of lithium in layered crystals of transition metal dichalcogenides

The incorporation of lithium into M0S2 crystals proceeds from 3V to 0.3V with respect to the Li / Li ⁺ half-cell (Hearing et al .; Lithium molybdenum disulphide battery cathode; U.S. Patent No. 4,224,390) in several stages and is reversible in all stages of incorporation . The average operating voltage of the MoS2 // electrolyte // Li cell is 1.8V relative to the half-cell Li / Li ⁺ with a capacity of about 160 mAh / g, which corresponds to the installation of about one mole of lithium per mole of molybdenum disulfide crystals, with 0.5 mole reversibly built. lithium.

The incorporation of lithium into T1S2 layer crystals takes place continuously in the potential range from 3 V to 1.6 V relative to the Li / Li ⁺ half-cell. The average operating voltage of the TiS2 member // electrolyte // Li is 2, IV relative to the half-cell Li / Li ⁺ with a capacity of about 230 mAh / g. This capacity corresponds to the incorporation of about one mole of lithium per mole of titanium disulfide crystals (CA Vincent and B. Ser osati, in Modem batteries, Arnold, London, 1997).

A technical problem

The disadvantages of the known solutions of the incorporation of lithium into the crystalline transition metal crystals of transition metal metals are the following:

• lithium incorporation at higher potentials than desired for electrodes in lithium ion batteries is carried out in the transition crystals of transition metal dichalcogenides;

• the amount of lithium incorporated in the transition metal dichalcogenide crystals is relatively small;

• simultaneous intercalation of solvated Li ⁺ electrolyte molecules (solv.) Between crystalline layers in transition metal crystals reduces the capacity.

Objectives and Objectives of the Invention

The object and object of the invention is to manufacture and use such an active electrode material that will allow the installation of lithium at the desired potentials, which will allow for a large amount of installed lithium, and will allow a large capacity over a wide temperature range.

According to the invention, the task is solved by preparing an electrode material based on bundles of single-layer transition metal dichalcogenide nanotubes and an electronic conductor. Such electrode material is suitable for the construction of an electrode for lithium ion batteries and accumulators. The object of the invention is solved by the use of an electrode material based on bundles of single-layer transition metal dichalcide nanotubes and an electronic conductor that, as an electrode material, enables the reversible incorporation of lithium into bundles of single-layer transition metal dichalcide nanotubes in lithium-ion batteries and accumulators according to independent patents. The problem of simultaneous intercalation of solvated electrolyte molecules in bundles of single-layer tubes of dichalcogenides is solved by the selectivity of intercalation spaces, since their dimension is large enough to allow lithium to be incorporated into the active material and at the same time small enough to allow simultaneous cointercalation of solvated electrolyte molecules.

The solution to the technical problem is the preparation and use of the active material with the general formula of transition metal dichalcogenides and the addition of an electronic conductor as an electrode material. The new material has a different structure than the layer crystals used so far, so it allows for a greater amount of lithium incorporated, and lithium incorporation takes place near the potential of lithium metal.

Description of the solution to the problem

The technical problem is solved by: A) fabrication of materials based on bundles of single-layer transition metal dichalcogenide nanotubes (for example M0S2) and an electronic conductor. B) This material is used to prepare an electrode into which lithium can be reversibly incorporated and built.

Description of pictures:

Figure 1 shows the electrode voltage containing an electrode material based on bundles of single-layer M0S2 nanotubes and a polyaniline-based electronic conductor against metal lithium over three consecutive cycles of cell charge and discharge.

Figure 2 shows the dependence of the amount of embedded Li on charge / discharge after cycles of action in an electrode material based on bundles of single-layer M0S2 nanotubes and a polyaniline based electronic conductor.

A) Preparation of electrode material based on M0S2 single-layer nanotube bundles and electronic conductor

Units of single-layer nanotubes of transition metal dichalcogenides are mixed with electronically conductive material (for example, sulfonated polyaniline or any other electronic conductor that allows electrical contact between single-layer nanotube bundles and the flow collector) with the addition of 1-methyl-2-pyrrolidone or a similar solvent. After drying, an electrode material is obtained.

B) Preparation of electrode from electrode material based on single-layer M0S2 nanotube bundles and electronic conductor

The partially dried electrode material is applied to a metal film, pressurized and dried. After drying, an electrode is obtained. The electrode is transferred to a dry chamber with an inert atmosphere (less than 1 ppm of water and less than 2 ppm of oxygen) and embedded in the electrochemical cell as a negative electrode. Lithium is electrochemically incorporated into the negative electrode by means of a counter electrode and an electrolyte. The incorporation and construction of lithium has been demonstrated by reversibly changing the electrochemical potential between 3V and OV with respect to the electrochemical potential of the reference Li / Li ⁺ electrode.

Example 1

From 0.5 to 2 mg bundles of single-layer molybdenum disulfide nanotubes are mixed with sulfonated polyaniline and l-methyl-2-pyrrolidone such that after drying, the weight fraction of single-layer molybdenum disulfide nanotubes is 85-99%. Partially dried mixture (electrode material) is applied to 8 mm diameter copper foil. The application is compressed at 1500 kg / cm ² and dried for 2 to 8 hours in a vacuum or inert atmosphere at a temperature of 70 to 120 ° C. The final coating thickness ranges from 20-100 pm. Transfer the dried electrode into a dry chamber (argon atmosphere, less than 1 ppm H2O) and incorporate it into the electrochemical cell as a negative electrode.

Example 2

-6 Bundles of single-layer molybdenum disulfide nanotubes are mixed with sulfonated polyaniline and l-methyl-2-pyrrolidone such that after drying, the weight fraction of single-layer molybdenum disulfide nanotubes is 1-85%. The electrode material obtained is treated in the same way as in Embodiment 1, and the electrode obtained is received for incorporation into electrochemical cells. The electrochemical reversible capacity of the electrodes thus produced is proportional to the mass fraction of molybdenum disulfide.

Example 3

Bundles of single-layer molybdenum disulfide nanotubes are mixed with sulfonated polyaniline and l-methyl-2-pyrrolidone. The resulting mixture (electrode material) is applied to a metal foil or mesh that is suitable for the function of the mechanical support and the collecting current in the negative electrodes for lithium batteries. The partially dried coating is compressed under pressure at a pressure of 100 to 10000 kg / cm ² , then the electrode is wound in combination with other electrodes and separatos or used in plan form. The dried electrode is transferred to a dry chamber and used as a negative electrode in an electrochemical cell.

Example 4

In the dry chamber, an electrochemical half-cell is assembled in which the negative (or working) electrode is identical or similar to the electrode described in Embodiments 1, 2, or 3. The positive (or auxiliary) and reference electrode are made of lithium metal. The technical design of a three-electrode cell may be the same as that described in M.Gaberšček et. al .; Electrochem and Solid State Lett., 3,171 (2000). Installation and construction of lithium in / out of the negative electrode takes place at a constant current of 10-25 mA / g, with the potential of the negative electrode varying between 3.0 and 0.0 V relative to the reference lithium electrode. The flow path of the negative electrode potential during installation and construction is illustrated in Fig. 1. It can be seen from the curves in Fig. 1 that up to 2.3 moles of Li per mole of M0S2 are incorporated into the negative electrode. In this case, at least 0.6 moles per mole of M0S2 is reversibly incorporated in Li. The proportion of reversibly embedded Li decreases monotonically with the number of cycles, but approaches the final value of 0.4-0.5 moles of Li per mole of M0S2 (Figure 2).

Example 5

In the dry chamber, an electrochemical half-cell is assembled in which the negative (or working) electrode is the same as the electrode described in Embodiments 1, 2, or 3. The auxiliary and reference electrode design and the technical design of the cell are optional. The installation and construction of lithium in / out of the negative electrode takes place at a constant or variable current between 0.1 and 1000 mA / g, with the potential of the negative electrode varying between 3.0 and 0.0 V depending on the potential of the Li / Li ⁺ half-cell.

The electrode material based on bundles of single-layer dichalcogenides of transition metals for producing electrode material is characterized in that, in addition to the bundles of single-layer dichalcogenides of transition metals, it also contains an electronic conductor and enables reversible electrochemical incorporation and construction of lithium at a potential V of 3.0 potential of the Li / Li ⁺ electrochemical half-cell. In this case, the proportion of bundles of single-layer transition metal dichalcogenide nanotubes in the electrode material is 1-99%; The installation of lithium takes place in the temperature range from -20 ° C to + 60 ° C.

Claims (5)

PATENT APPLICATIONS 1. Active material based on bundles of single-layer transition metal dichalcogen nanotubes, characterized in that, in addition to bundles of single-layer transition metal dichalcogen nanotubes, it contains at least an electronic conductor and enables reversible electrochemical installation and construction of lithium in the potential range from 3.0 V to 0 V depending on the potential electrochemical half-cell Li / Li ⁺ . Active material according to claim 1, characterized in that the proportion of bundles of single-walled transition metal dichalcogenides nanotubes in the electrode material is 1-99%. Active material according to claim 2, characterized in that the electronic conductor is a conductive polymer that allows electrical contact between the bundles of single-walled transition metal dichalcogenide nanotubes and the flow collector. Use of a material according to claims 1 to 3, characterized in that the material is made of an electrode for use in lithium batteries, accumulators or related galvanic cells. Use of a material according to claim 4, characterized in that the installation of lithium takes place in the temperature range from -20 ° C to + 60 ° C.