TWI429595B - The method for forming the Anode material composite of TI, LI, SN for battery - Google Patents

Description

Method for forming battery anode material with Ti, Li and Sn composite materials

The invention is a novel negative electrode material with high safety, high electric capacity and high service life, and is a preparation method of a battery anode material with low cost and simple operation, and is suitable for various energy storage devices, such as lithium ion secondary batteries. And super capacitors.

Nowadays, the size of electronic equipment, information technology, biomedical equipment and equipment is becoming lighter and thinner. Therefore, the battery used for it is expected to have the advantages of small size and long-term use to maintain high storage capacity and high discharge capacity. Lithium ion batteries that meet these traits are gradually receiving attention from relevant academics and industry.

The main components of the lithium ion battery include a positive electrode (LiCoO ₂ , LiMn ₂ O ₄ , LiFePO _{4 ,} etc.), an electrolytic solution, a separator, and a negative electrode (carbonaceous material, titanium-based material, etc.). The working principle of a lithium-ion battery is to use lithium ions to perform embedding and embedding between the positive and negative electrodes to complete the charge-discharge reaction, and the charge-discharge chemical reaction can be summarized as the following chemistry. The reaction formula, wherein M is Co, Ni or Mn, and the reaction direction is toward the right when charging, and the reaction direction is toward the left when discharging:

Positive reaction: LiMO ₂ Li(1-x)MO ₂ +xLi ⁺ +xe ^-

Negative reaction: C ₆ +xLi ⁺ +xe ^- LixC ₆

Total reaction: LiMO ₂ + C ₆ Li(1-x)MO ₂ +LixC ₆

In recent years, various transition metal oxides have been studied for negative electrodes of lithium ion batteries, such as MoO ₂ , SnO ₂ , CoO ₂ , CuO, FeO, Li ₄ Ti ₅ O ₁₂ and TiO ₂ , among which TiO ₂ and Li _{4 .} Titanium-based materials such as Ti ₅ O ₁₂ have been widely used. Due to the stable crystal structure of these materials, the volume change rate caused by charge and discharge is extremely small (less than 0.2%), so the cycle life is excellent (1,500 cycles or more). It is considered to replace the traditional carbon-based material as a negative electrode material for lithium ion batteries to solve the safety problem, but its poor conductivity and low capacitance (about 180 mAh/g) are the most difficult problems to be overcome as the negative electrode of lithium ion batteries.

U.S. Patent No. 6,007,945 discloses the use of a solid solution method for mixing TiO ₂ and SnO ₂ in a different ratio to a negative electrode material for a lithium ion battery. The commercial TiO ₂ and SnO ₂ powders were uniformly mixed in a ratio of Ti to Sn atomic ratio of Ti ₆ Sn ₅ and Ti ₂ Sn, and the mixture was sintered at 1100 ° C and pulverized to an average particle diameter of about 15 μm. Then, the active powder was uniformly mixed with 5 wt% of fine petroleum coke and polyvinylidene fluoride to prepare a working electrode, and LiCoO _{2 was used} as a counter electrode for electrical testing. The results show that the reversible capacities of the electrodes with atomic ratios of Ti ₆ Sn ₅ and Ti ₂ Sn are 1130 mA/cm ³ and 1110 mA/cm ^{3 respectively} (electrode density is 3.65 g/cm ³ ), and the initial operating voltage of the LiCoO ₂ full cell is about 3.5 V. And a stable voltage of 3.2V can be maintained after 50 cycles. Although the above synthetic method can improve the capacitance of TiO ₂ , since the TiO ₂ is easy to form a Li-Ti-O structure during charge and discharge, the material generates a large amount of irreversible capacity, so many literature studies have changed the base of the composite material to a low irreversible capacity. And a structurally stable lithium titanate (Li ₄ Ti ₅ O ₁₂ ) material.

Document Materials Research Bulletin , 46 (2011) 492-500 discloses a novel composite material, Sn/Li ₄ Ti ₅ O _{12 , which is} uniformly mixed with self-made Li ₄ Ti ₅ O ₁₂ and Sn by high-energy mechanical ball milling. The authors used a solid state reaction method to uniformly mix the quantitative organic lithium salt with titanium dioxide and then sintered at various temperatures to obtain Li, Ti, O composites, which were sintered at 800 ° C to obtain a pure crystal image of Li ₄ Ti ₅ O ₁₂ , and then by chemical reaction method. Mixing SnCl ₂ . The 2H ₂ O and NaBH ₄ solvents were used to obtain nano Sn powder, and finally Li ₄ Ti ₅ O ₁₂ and Sn were mixed into Sn/Li ₄ Ti ₅ O ₁₂ in different ratios. The results show that Li ₄ Ti ₅ O ₁₂ can suppress the problem of excessive volume expansion of Sn during charge and discharge and Sn can make Li ₄ Ti ₅ O ₁₂ have superior conductivity and make Sn/Li ₄ Ti ₅ O ₁₂ have good circulation. Stability and high capacity, the first discharge capacity can reach 321mAh/g when the weight ratio of Li ₄ Ti ₅ O ₁₂ :Sn is 70:30, and it can maintain 300mAh/g after 30 cycles.

Document Journal Alloys and Compounds , 462 (2008) 404-409 discloses a Li ₄ Ti ₅ O ₁₂ -SnO ₂ composite obtained by depositing a Sn, O compound on a self-made Li ₄ Ti ₅ O ₁₂ by a chemical deposition method. First, different ratios of SnCl ₂ will be used. After xH ₂ O is contained in an alcohol solvent, Li ₄ Ti ₅ O ₁₂ and NH _{3 are} sequentially added. H ₂ O was deposited on the surface of the Li ₄ Ti ₅ O ₁₂ material, and then sintered at 500 ° C for 3 hr to obtain a Li ₄ Ti ₅ O ₁₂ -SnO ₂ composite. The results show that this method uniformly qualifies SnO ₂ on the surface of Li ₄ Ti ₅ O ₁₂ and has good cycle life stability and capacitance. The first discharge capacity of 5% 5% of SnO ₂ modified on Li ₄ Ti ₅ O ₁₂ surface is 443 mAh. /g was maintained at 189 mAh/g after 42 cycles.

From the above literature, the synthesis of lithium titanate materials and tin compounds has been extensively studied in the near future, but it is found that the capacity retention rate is not as good as that of Li ₄ Ti ₅ O ₁₂ , presumably because the tin compounds are more coated with Li _{4 . On the} surface of Ti ₅ O ₁₂ , the volume of the tin compound changes during charging and discharging, resulting in poor cycle life.

In view of the above-mentioned background of the invention, in order to meet the special needs of the industry, the present invention provides a Ti, Li, Sn composite material having high capacitance, high service life and high safety, which can be used to solve the problem that the above-mentioned conventional art fails to achieve. .

In view of this, one of the objects of the present invention is to prepare a Ti, Li, and Sn composite material with high capacitance, high service life and high safety by a simple and low-cost operation method, which can be used for mass production, for lithium. Ion batteries are of great help in the promotion of electric vehicles and can promote the development of electric vehicle related industries. The present invention mainly synthesizes SnO ₂ and TiO ₂ into a solid solution material to increase the capacitance and suppress the volume change of SnO ₂ during charge and discharge to increase the cycle life, and then doping Li into the solid solution. In order to reduce the irreversible capacity, it becomes a new Ti, Li, and Sn composite material. The invention prepares a Ti, Li and Sn composite material with high electric capacity, high service life and high safety for the simple and low cost operation method, and is suitable for mass production, and is important for the promotion of lithium ion batteries in electric vehicles. Help and promote the development of electric vehicle related industries.

In order to achieve the above object, the present invention provides a method for preparing an electrode material, comprising: providing an acid plating bath; adding titanium dioxide powder, a metal salt and a reducing agent to the acid plating bath to obtain a precursor; The precursor is heat treated once to obtain a SnO ₂ /TiO ₂ solid solution; then a lithium source is uniformly mixed with the solid solution and then subjected to secondary heat treatment to obtain an electrode material.

In a preferred embodiment, the acidic plating bath is composed of an acid and a solvent. The acid is preferably formic acid, benzoic acid, sulfuric acid, hydrochloric acid, borofluoric acid, acetic acid, nitric acid or a combination thereof. The solvent is preferably water, an alkane, a ketone or an aldehyde. Classes, alcohols, ethers, aromatic hydrocarbons, kerosene or combinations thereof. In a preferred embodiment, the temperature of the acid plating bath is from 40 ° C to 100 ° C. In a preferred embodiment, the crystal phase of the titanium dioxide is rutile, anatase, brookite or a combination thereof. In a preferred embodiment, the metal salt is a tin compound, a telluride, a telluride or a combination thereof. In a preferred embodiment, the reducing agent is thiourea, sodium sulfide, sodium thiosulfate, sodium thiosulfate or a combination thereof.

In a preferred embodiment, the method further comprises a drying step prior to the heat treatment step. The drying step is preferably carried out at 60 ° C to 120 ° C. . Furthermore, the method preferably further comprises a washing step prior to the drying step. In a preferred embodiment, the lithium source is lithium carbonate, lithium hydroxide or a combination thereof. In a preferred embodiment, the two heat treatments are carried out at 200 to 1300 °C. In a preferred embodiment, the crystal phase of the titanium dioxide is rutile, anatase, brookite or a combination thereof. In a preferred embodiment, the metal salt is a tin compound, a telluride, a telluride or a combination thereof. In a preferred embodiment, the electrode material is used as a negative electrode. In a preferred embodiment, the electrode material is made by the method described above.

As can be seen from the above, the process of the present invention is relatively simple and convenient to handle, and does not require special equipment, and is particularly suitable for mass production, quite in line with the industry. Planning and demand for the production line.

The present invention is directed to Ti, Li, Sn composite materials, and in order to fully understand the present invention, detailed structures, elements, and method steps thereof are set forth in the following description. Obviously, the practice of the present invention is not limited to the specific details familiar to those skilled in the art of Ti, Li, Sn composites. On the other hand, well-known structures and elements thereof are not described in detail to avoid unnecessary limitation of the invention. In addition, in order to provide a clearer description and to enable those skilled in the art to understand the present invention, the various parts of the drawings are not drawn according to their relative sizes, and the ratio of certain dimensions to other related scales will be highlighted. The exaggerated and irrelevant details are not completely drawn, in order to simplify the illustration. The preferred embodiments of the present invention are described in detail below, but the present invention may be widely practiced in other embodiments and the scope of the present invention is not limited by the scope of the appended claims.

The invention provides a simple method for preparing an electrode material, and the electrode prepared by the method is applied to a battery, which not only enables the battery to have a high electric capacity, but also has a long service life.

The present invention provides a method for preparing an electrode material, comprising: providing an acid plating bath; adding titanium dioxide powder, a metal salt, and a reducing agent to the acid plating bath to obtain a precursor; and applying the precursor once After heat treatment, a SnO ₂ /TiO ₂ solid solution is obtained; then a lithium source is uniformly mixed with the solid solution and then subjected to secondary heat treatment to obtain an electrode material.

The acidic plating bath used in the present invention is composed of an acid and a solvent, and the ratio thereof is well known to those skilled in the art, and will not be further described herein. The acid plating bath may be obtained commercially or directly, or may be self-utilizing other chemical configurations when an operator desires to carry out the method of the invention. In the present invention, the acid includes, but is not limited to, formic acid, benzoic acid, sulfuric acid, hydrochloric acid, borofluoric acid, acetic acid, nitric acid or a combination thereof, with borofluoric acid being preferred.

In the case of a solvent, it may be water, an alkane such as ethane, propane or pentane, a ketone such as acetone, methyl ethyl ketone or N-methyl-2-tetrahydropyrrolidone, or an aldehyde such as : butyraldehyde), alcohols (methanol, ethanol, propanol, butanol, pentanol or isopropanol), ethers (such as: diethyl ether), aromatic hydrocarbons (such as benzene, toluene or xylene) And kerosene or a combination thereof, but is not limited thereto, and water is preferred. The temperature of the acid plating bath is preferably 40 ° C to 100 ° C. In the present invention, the crystal phase of the titanium oxide is not particularly limited, but is preferably rutile, anatase, brookite or a combination thereof, and rutile is more preferable.

The metal salts used in the present invention may be tin compounds, tellurides, tellurides Or a combination thereof, but is not limited thereto. The tin compound may be tin dichloride, tin tetrachloride, tin sulfate, tin borofluoride or a combination thereof; the telluride may be barium chloride, barium sulfate, barium borofluoride or a combination thereof; It is cerium dichloride, cerium tetrachloride, cerium bromide or a combination thereof.

The amount of the metal salt to be added is not particularly limited, and the present invention can be carried out as long as the metal salt is added to the acidic plating bath and the concentration of the obtained metal ion is within the range of the saturated concentration. Preferably, the concentration of metal ions in the acidic solution is between 0.01 M and 0.40.

In the practice of the present invention, the relative amounts of titanium dioxide and metal salts are mainly considered, and therefore, the volume to be used for the acid plating bath is not limited. In the method of the present invention, the relative amount of titanium dioxide and the metal salt is determined by the operator in various considerations (for example, the type of titanium dioxide selected and its surface area, the performance of the anode material to be obtained, the cost of the material, etc., etc. Etc.), and there is variation, therefore, the relative amount of titanium dioxide and the metal salt should not be limited. In order to make it easier for the operator to implement the present invention, the inventors have also proposed the following dosages. It is estimated that the amount of metal ions generated by the metal salt in the acidic plating bath is preferably 0.35 M or less, more preferably 0.10 M to 0.35 M, and particularly preferably 0.20 M. ~0.25M between.

In addition, it must be stated again that the metal salts in the acid plating bath, The choice of the type of acid and solvent and the amount of addition thereof depend on the cost of the operator, the convenience of material selection, the ease of operation, or the degree to which the electrode material can be used to assemble the battery. Therefore, There should be no restrictions.

The reducing agent used in the present invention is not particularly limited as long as it can reduce the metal ions in the reactants and deposit them on the surface of the titanium oxide material. For example, it may be thiourea, sodium sulfide, sodium thiosulfate, sodium thiosulfate or a combination thereof. In a preferred embodiment, the reducing agent is sodium thiosulfate.

In the present invention, the first heat treatment step may further comprise a drying step. However, since the temperature of the heat treatment environment is higher than room temperature, the removal of the reducing agent and the acid plating bath may be accelerated, so that the practical operation is performed. In the above, the drying treatment is generally carried out together with the heat treatment. The drying step is preferably carried out at 60 ° C to 120 ° C. In order to reduce the amount of impurities in the precursor, the drying step may further comprise a step of washing the precursor.

The second heat treatment step comprises a step of mixing a SnO ₂ /TiO ₂ solid solution and a lithium source. The two heat treatment steps of the present invention are generally preferably carried out at 400 to 1300 °C. As for the time of heat treatment, those skilled in the art should know that the higher the temperature of the heat treatment, the shorter the time required. Therefore, the heat treatment time mainly depends on the temperature of the heat treatment. Generally, the heat treatment time is preferably 10 minutes. 180 minutes, more preferably 10 minutes to 120 minutes.

The lithium source used in the present invention is not particularly limited as long as it can be doped into the SnO ₂ /TiO ₂ solid solution during the secondary heat treatment. For example, it may be lithium carbonate, lithium hydroxide or a combination thereof. In a preferred embodiment, the lithium source is lithium carbonate.

In addition, in order to prevent the precursor from being oxidized during the heat treatment before drying, the heat treatment is preferably carried out under an inert gas atmosphere or in the presence of a small gas atmosphere, that is, a gas atmosphere pressure value. Below the condition of 10 ^-2 torr. To be carried out under an inert gas atmosphere, the inert gas is preferably selected from nitrogen, argon, helium, carbon dioxide, nitrogen dioxide or a combination thereof. Of course, the presence of moisture and oxygen should be avoided in this gas atmosphere.

Although a variety of preferred conditions have been exemplified above, those skilled in the art will appreciate that as long as the electrode material is finally obtained, the temperature and operating time of the heat treatment may not be limited to a specific numerical range, and therefore, the operator may Factors such as equipment limitations and time costs are used to consider the temperature and time to be taken during heat treatment. As described above, the crystal phase of titanium dioxide is not particularly limited, but is preferably rutile, anatase, brookite or a combination thereof. Among them, rutile is better.

The term "reduced and then heat-treated metal salts" as used in the present invention refers to a product obtained by subjecting a metal salt to reduction, followed by heat treatment, which may be a metal, a metal compound or a mixture thereof. The metal salt which is subjected to the heat treatment after reduction is a metal, a metal compound or a mixture thereof depending on the reaction environment. Specific examples of the metal salt which has been subjected to heat treatment after reduction include tin metal, tin sulfide or tin oxide, but are not limited thereto.

The electrode material obtained by the method of the present invention can be used as a lithium ion secondary battery as well as other electrochemical devices. Generally, it is preferred to use it as a negative electrode material. The electrode material of the present invention has the advantages of high safety, high capacitance, low capacitance decay rate, long service life and high stability.

<Preparation of negative electrode piece>

The anode material is uniformly mixed with a conductive material, a binder and a solvent to obtain a paste, which is then coated on a sheet-like current collector material (coated on both sides or on one side, In the embodiment of the invention, the coating material is coated on one side, and after drying, a current collecting material having one or two coating layers formed on the surface is obtained, and in addition, in order to mold and enhance the capacity density of the subsequently produced battery, And strengthening the structure of the coating layer, and the adhesion between the coating layer and the current collector, optionally followed by pressurization of the coating layer by a press to form the negative electrode tab It is worth noting that the hardness of titanium dioxide itself is high, so the pressure roller material should be carefully selected to prevent the press from being damaged.

The changes in the types, amounts, shapes, etc. of the above-mentioned conductive materials, adhesives, solvents, and collector materials, etc., may be determined by the industry in accordance with their professional literacy and needs; for example, in general practice, As the conductive material, carbon black, nano carbon fiber or the like may be used as the conductive material, and the amount thereof is usually about 0 to 20% by weight of the total weight of the negative electrode material, the conductive material and the binder; wherein the conductive material may not be added. The thickness of the coating layer is preferably from 20 to 350 μm.

In the above adhesive, it is preferred to use chemical stability and electrochemical high voltage stability of the electrolyte, and the amount thereof is usually about 1 to 10% by weight of the negative electrode material. Fluorine-based polymers can be used as the binder. [Polyvinylidene fluoride (PVDF), Polytetrafluoroethylene], and polyolefins are commonly used in the industry. Polyethylene (PE) is commonly used in the industry. Polyvinyl alcohol (PVA), Styrene-butadiene rubber (SBR) and cellulose [usually used as Carboxymethylcellulose] Etc., you can also mix and use for this.

In terms of solvent, it may generally be water, N-methyl pyrrolidone, dimethylformamide, alcohols such as ethanol, isopropanol, etc., or a mixture of such solvents; It is water and N-methylpyrrolidone, especially N-methylpyrrolidone, which is most commonly used; and the control of the type and amount of solvent has been changed in the industry and is a well-known technique, so it is a familiar The technical field of the present invention can be changed according to its professional literacy and needs, and therefore will not be described herein.

In the case of the above-mentioned current collector material, materials such as copper and nickel may be used, and the shape is not limited, and is usually in a thin state such as a foil shape or a mesh shape; and the size (for example, length, width, thickness, weight of use, etc.) ), depending on the size of the negative electrode piece to be produced, the thickness is preferably 5 to 20 μm.

Construction and other components of lithium ion secondary batteries

As shown in FIG. 1, a lithium ion secondary battery 1 includes an upper cover 11 and a lower cover 12, which are mutually engageable to define a closed space (not shown in FIG. 2); the lithium ion The battery 1 further includes a spring washer 13 disposed in the direction of the lower cover 12, a stainless steel wafer 14, a negative electrode tab 15, an isolation film 16, and a positive pole tab 17, and An electrolyte (not shown) filled in the sealed space.

It should be emphasized that, in the context of the present invention, a spring gasket, a stainless steel wafer, a negative pole piece, a separator, a positive pole piece, and any of the aspects or materials known in the art can be used. The electrolyte is used; and the changes in the types, manufacturing methods, and dosages of the above battery components are well-known in the industry, and the industry can control them according to their professional qualities and their needs. Therefore, only a brief description will be given in this application.

<Positive pole piece>

The positive electrode tab is formed in a manner similar to the above negative electrode tab, except that the anode material is replaced by a positive electrode material. The material of the positive electrode material is a transition metal oxide of lithium, such as the compound LiM _(1-x) M' _x O ₂ (wherein the value x is 1 or less) or LiM _(2-y) M' _y O ₄ ( Wherein the value y is less than or equal to 2), and M and M' are respectively selected from the group consisting of: and at least one of M and M' is a transition metal: titanium (Ti), vanadium (V) ), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), or tin (Sn); its preparation can be referred to by China The contents of Chapter 3 of the book "Lithium Ion Battery" (first edition, May 2002) published by Central South University Press. Further, the raw material of the positive electrode material may be a transition metal oxide containing two or more kinds of lithium, or may be combined with other battery materials such as lithium carbonate. In addition, the positive electrode tab may also be directly a piece of lithium foil.

<isolation film>

The separator 15 is mainly used for insulation, preventing short circuit of the battery, improving safety, and allowing ions to pass between the positive and negative pole pieces. The separator suitable for use in the present invention is not particularly limited in type, for example, a solid form such as a non-woven fabric or a porous film which is generally used in the field, or a gel state, etc.; Olefin polymer compound (polyolefine), especially polypropylene/polyethylene (PP/PE), or polypropylene/polyethylene/polypropylene (PP/PE/PP), among which PP/PE/PP More common.

<electrolyte>

The electrolyte suitable for use in this case is a non-aqueous system, and the electrolyte is composed of a non-aqueous solvent and an electrolyte dispersed in the solvent. Suitable electrolytes are lithium hexafluorophosphate (LiPF ₆ ), lithium fluoroborate (LiBF ₄ ), lithium bistrifluoromethylsulfonimide [LiN(CF ₃ SO ₂ ) ₂ ], trifluoromethanesulfonic acid, which are commonly used in the art. A lithium salt such as lithium (LiCF ₃ SO ₃ ), or a combination thereof, wherein preferred is a mixture selected from LiPF ₆ , LiBF ₄ , and the like. The electrolyte concentration in the electrolyte is recommended to be 0.1 to 2.0 M in the present case, preferably 0.5 to 1.2 M.

The non-aqueous solvent in the electrolyte is solid and gelatinous in type. Or various forms of liquid can be used. As for the liquid non-aqueous solvent, it can be selected by users in the field, for example, carbonates [such as ethylene carbonate, propylene carbonate, dimethyl carbonate, carbonic acid). Diethyl carbonate, and methylethyl carbonate, etc., furans [such as tetrahydrofuran (terrahydrofuran), ethers [such as diethyl ether, etc., thioethers] such as methyl rings A combination of a methyl-sulfolane or the like, a nitrile such as acetonitrile, propanenitrile, or the like.

The solid non-aqueous solvent may be a polymer compound, and may be selected, for example, from an ether-based polymer such as polyethylene oxide and a crosslinked body thereof, or a polymethacrylate. Molecular, polyacrylate polymer, fluorine polymer compound [for example, polyvinylidene fluoride (PVDF) and vinylidene fluoride-hexafluoropropylene copolymer], or The combination of these, etc.

<electrolyte>

The type of the electrolyte is not particularly limited, and may be, for example, a lithium salt [e.g., LiPF ₆ , LiBF ₄ , LiN(CF ₃ SO ₂ ) ₂ , LiCF ₃ SO ₃ ], and the concentration range thereof is preferably 0.1 to 1.5 M, preferably It is 0.5~1.2M. The electrolyte may be obtained by dissolving the electrolyte in the above liquid non-aqueous solvent; however, when a solid non-aqueous solvent is used, an organic solvent (for example, an alkane, a ketone, an aldehyde, or the like) may be used first. Alcohol, ether, benzene, toluene, xylene, kerosene, or a combination thereof, first dissolves and uniformly mixes an electrolyte and the solid non-aqueous solvent, and then heats to evaporate the organic solvent to obtain an electrolysis liquid. In each of the application examples, the electrolyte component selected in the present case is a LiPF ₆ electrolyte having a concentration of 1 M, and the solvent portion is a mixture of ethylene carbonate and dimethyl carbonate mixed at a weight ratio of 1:1; the separator 16 is The PP/PE/PP material is used; and the positive electrode tab 17 is a lithium foil.

<Example>

The present invention will be further described in the following examples and comparative examples, but it should be understood that these examples are for illustrative purposes only and are not to be construed as limiting. Further, unless otherwise specified, the mixing of each of the materials in the examples and the comparative examples and subsequent tests and evaluations were carried out under normal temperature and normal pressure.

[Chemicals and related battery parts] <Battery anode material>

(1) Acid: Boric acid, Panreac, having a purity of 35.0%.

(2) Solvent: water.

(3) Titanium dioxide.

(4) The reactant: Sn(BF ₄ ) ₂ , Acoros, having a purity of 50.0%.

(5) Reducing agent: Na ₂ S ₂ O ₄ , purity of 98.2%.

(6) Lithium source: Li ₂ CO ₃ , purity of 98.2%.

(7) Conductive material: carbon black.

<Negative pole piece>

(8) Solvent: N -methyl-2-tetrahydropyrrolidone (NMP, C ₅ H ₉ NO), purity 99.5%.

(9) Adhesive: PVDF, molecular weight of about 304,000.

(10) Current collector: copper foil with a thickness of 15 μm.

<electrolyte>

(11) Electrolyte: LiPF ₆ with a purity of 99.0%.

(12) Solvent: ethylene carbonate and dimethyl carbonate, and the purity was 99.0%.

<Other battery parts>

(13) Upper and lower cover.

(14) Spring washers.

(15) Stainless steel discs.

(16) Isolation film.

(17) Positive electrode piece: lithium foil, purity 99.9%, diameter 1.65 cm The wafer.

[Examples and Comparative Examples]

The operating conditions of the respective examples and comparative examples will be separately described below, and will be listed later in Table 1.

[Example 1]

Embodiment 1 is a method of performing one of the following steps to prepare a battery negative electrode material:

(A) After mixing the volume of borofluoric acid and water to 47.3 mL and 485.8 mL, respectively, the temperature was raised to 60 ° C to obtain an acidic plating bath.

(B) sequentially adding 37.5 g of rutile phase titanium dioxide and 49.3 mL of borofluoride tin to a dewatering treatment at a temperature of 110 ° C for 2 hours (estimated by input of titanium dioxide carbon material per gram, the acidic solution The amount of medium metal ions was 0.0018 mol, and 17.41 g of sodium sulfite was uniformly mixed for 30 minutes, and the precursor was taken out and washed several times, and then transferred to an oven set to a temperature of 100 ° C until a solid was obtained. Dry matter.

(C) The dried product was placed in a crucible and then transferred to a high temperature furnace set to 600 ° C and filled with nitrogen gas for a heat treatment. After 120 minutes, it was naturally cooled and taken out to obtain a SnO ₂ /TiO _{2 .} Solid solution material.

(D) Finally, 7.3 g of SnO ₂ /TiO ₂ solid solution material was uniformly mixed with 0.7 g of Li ₂ CO ₃ , placed in a crucible, and transferred to a high temperature furnace filled with nitrogen gas at a temperature of 600 ° C for two times. After heat treatment, after 120 minutes, it was naturally cooled and taken out to obtain a Ti, Li, and Sn composite.

[Embodiment 2]

Li ₂ CO ₃ in the step (D) was 2.1 g.

[Example 3]

Li ₂ CO ₃ in the step (D) was 2.8 g.

[Comparative Example 1]

Comparative Example 1 is a rutile phase titanium dioxide which has been subjected to a water removal treatment at a temperature of 110 ° C for 2 hours without any treatment.

[Application Example] <Lithium Ion Secondary Battery>

The negative electrode materials respectively obtained according to the methods described in the respective examples/comparative examples are each doped with carbon black (ie, conductive material) and PVDF (ie, binder) in a ratio of 60:20:20 by weight. And obtaining a solid composition, and then taking 20% by weight of the solid composition of N-methyl-2-tetrahydropyrrolone (NMP, C ₅ H ₉ NO), and uniformly mixing with the solid composition to form a paste Things.

Applying each paste to one side of the copper foil, and then smoothing it with a 250 μm doctor blade to make the total thickness of the copper foil and the paste up to 250 Μm, and then placed in an oven set to 110 ° C [manufactured by Kathy Drying Electromechanical Co., Ltd.] to remove residual NMP, after 2 hours, a pole piece was obtained. Then, a wafer having a diameter of 16 mm is cut by a tableting machine, which is a negative electrode sheet 15 which can be subsequently prepared to separately prepare a lithium ion secondary battery 1 as shown in FIG.

Referring to FIG. 1 , an upper cover 11 , a lower cover 12 , a spring washer 13 , a stainless steel wafer 14 , a separator 16 , a positive electrode sheet 17 , and an electrolyte are prepared for each of the negative electrode tabs 15 . (1M LiPF6 electrolyte, the solvent part of which is mixed with ethylene carbonate and dimethyl carbonate in a weight ratio of 1:1), and has a water content of 10 ppm or less and a battery capping machine. Glove box manufactured by Poly Industrial Co., Ltd. [manufactured by Unilab Mbraum, model No. Proj-4189], these components are assembled in the arrangement shown in Figure 2, and capped with the battery capping machine ( To ensure its closure, a separate coin-type battery is obtained; this is the desired lithium-ion secondary battery.

<Effect test>

The negative electrode materials obtained by the methods shown in the respective examples/comparative examples, and the lithium ion secondary batteries thus prepared were subjected to the following respective efficacy tests:

[Initial charge/discharge test]

Each of the lithium ion secondary batteries is charged with a constant current by a charge and discharge tester (manufactured by Taiwan Jiayou Technology Co., Ltd., model BAT-750B) at a current of 0.326 mA cm ^-2 (about 0.1 C). The instrument displays that the battery circuit voltage reaches 0.1V, and obtains the first charge capacity value of the battery; after 5 minutes, the battery is subjected to constant current discharge to a circuit voltage of 3.0V at a current of 0.326 mA cm ^-2 . Thus, the first discharge capacity value of the battery was obtained, and then the initial charge and discharge efficiency of each battery was calculated by the following formula.

In addition, by dividing the first charge capacity value of each battery by the weight of the titanium dioxide in the negative electrode tab of the battery, an average of "the battery negative electrode obtained by the methods described in the respective examples and comparative examples of the present invention can be obtained. Material" 1 gram, the charge/discharge capacity (in mAh/g) of the corresponding battery. The initial charge/discharge efficiency (unit: "%") obtained by the respective examples/comparative examples, and the charge/discharge capacity (unit: mAh/g) are listed in Table 1.

[Fifty charge/discharge test]

The operation method of this test is to continue the above-mentioned [initial charge/discharge test] for fifty times, and each time the charge/discharge test is completed, the next one is stopped after five minutes of stopping; the battery is obtained. For a total of fifty times of charge and discharge capacity values, it is worth noting that the capacity of the titanium dioxide material is stable at about the fifth charge and discharge. Therefore, the battery is calculated according to the value of the fiftyth discharge capacity. Cycle characteristics.

In addition, by dividing the value of the 50th discharge capacity of each battery by the weight of titanium dioxide in the negative electrode sheet of the battery, it is also possible to obtain an average of 50 grams of the corresponding battery from the carbon material. Discharge capacity (in mAh/g). The values of the twentieth discharge capacity and cycle characteristics (in "%") of the batteries obtained in accordance with the respective examples/comparative examples and subsequent preparations are shown in Table 1.

The first discharge capacity of each of the examples shown in Table 1 (shown as "1st discharge capacity" in Table 2) and the fifth discharge capacity (shown as "5th in Table 2" are listed in Table 2. Discharge capacity"), the 50th discharge capacity ("50th discharge capacity" in Table 2), discharge efficiency, fifth Ten cycle characteristics (denoted as "50th cycle characteristics" in Table 2), relative to the difference of the comparative example using the same titanium dioxide; those marked with "+" in the data represent the obtained in this test item. The test value is higher than the corresponding comparative example.

According to the test results of the above various examples, in Tables 1 to 2, the battery negative electrode material obtained by the method of the present invention is shown, regardless of the untreated rutile titanium dioxide, regardless of the first discharge capacity, The 50th discharge capacity, discharge efficiency, and twentieth cycle characteristics have more excellent performance. The above-mentioned batteries were selected, and the discharge capacity values of the other 50 times were sorted into the results shown in Fig. 2, from which the cycle life of each battery was also known.

As can be seen from the figure, the battery assembled by the negative electrode materials produced in Examples 1 to 3 has not only a large discharge capacity but also a deterioration in the performance of each charge and discharge capacity. Not all of them are better than Comparative Example 1, but they can still be maintained at a certain level; therefore, the batteries configured in Examples 1 to 3 will have a more stable performance and are expected to have a longer service life. Different lithium compounds may be selected as the source of lithium to carry out the method; for example, lithium hydroxide, both of which can successfully obtain a battery negative electrode material having good characteristics. A negative electrode material having good characteristics can also be obtained by different secondary heat treatment temperatures and time.

It can be seen from the above that when the Ti, Li, and Sn composite materials are further formed into a negative electrode sheet, the lithium ion secondary battery obtained correspondingly can have a high discharge capacity and can supply electric energy continuously and for a long time, and Under long-term use, the battery can still maintain a high discharge capacity, thus increasing its service life. Moreover, since the negative electrode material is made of a highly safe Ti-based material, the characteristics are very consistent. Market demand. The method of the invention is very simple to operate, no special equipment or materials are needed, and the obtained anode material can be used without further purification, thereby greatly reducing the production cost, so the method of the invention can be produced at a low cost. After the appropriate anode material, it is further used as a battery with high safety, large discharge capacity and long service life, creating a huge commercial interest for the manufacturer.

Obviously, many modifications and differences may be made to the invention in light of the above description. It is therefore to be understood that within the scope of the appended claims, the invention may be The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the claims of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the present invention should be included in the following claims. Within the scope.

1‧‧‧Lithium ion secondary battery

11‧‧‧Upper cover

12‧‧‧ Lower cover

13‧‧‧Spring washer

14‧‧‧Stainless steel discs

15‧‧‧Negative pole piece

16‧‧‧Separator

17‧‧‧ positive pole piece

1 is an exploded perspective view of the present invention, illustrating the positional relationship of each component of a lithium ion secondary battery and its arrangement; and FIG. 2 is a cycle life test chart of the present invention, illustrating a comparative example 1 and an embodiment. The battery negative electrode material obtained in 1~3 is the discharge capacity value obtained each time when the charge/discharge test is performed 50 times after further making a battery.

1‧‧‧Lithium ion secondary battery

11‧‧‧Upper cover

12‧‧‧ Lower cover

13‧‧‧Spring washer

14‧‧‧Stainless steel discs

15‧‧‧Negative pole piece

16‧‧‧Separator

17‧‧‧ positive pole piece

Claims (7)

A method for forming a battery anode material of a Li, Sn composite material, the method for forming a battery anode material having a Ti, Li, and Sn composite material comprises: providing an acid plating bath; and adding a titanium dioxide powder, a metal salt, and a reducing agent Adding to the acidic plating bath to obtain a precursor; the precursor is subjected to a heat treatment once, wherein the primary heat treatment is performed by a temperature of 600 to 800 ° C and filled with nitrogen to form a SnO ₂ /TiO ₂ solid. a solution material; after uniformly mixing the SnO ₂ /TiO ₂ solid solution material and a lithium source, performing a second heat treatment, wherein the second heat treatment is performed by a temperature of 700 to 1300 ° C and filled with nitrogen gas to form The battery anode material of the Ti, Li, Sn composite material, wherein the lithium source is lithium carbonate, lithium hydroxide or a combination thereof. The method for forming a battery anode material having a Ti, Li, and Sn composite material according to the first aspect of the invention, wherein the acid plating bath further comprises: an acid, the acid is formic acid, benzoic acid, sulfuric acid, hydrochloric acid, Boric acid, acetic acid, nitric acid or a combination thereof; and a solvent which is water, an alkane, a ketone, an aldehyde, an alcohol, an ether, an aromatic hydrocarbon, kerosene or a combination thereof. The method for forming a battery negative electrode material having a Ti, Li, and Sn composite material according to the first aspect of the invention, wherein the temperature of the acidic plating bath is 40 ° C to 100 ° C. The method for forming a battery negative electrode material having a Ti, Li, and Sn composite material according to claim 1, wherein the titanium dioxide powder is rutile, anatase, brookite or a combination thereof. The method for forming a battery negative electrode material having a Ti, Li, and Sn composite material according to claim 1, wherein the metal salt is a tin compound, a telluride, a telluride or a combination thereof. The method for forming a battery anode material having Ti, Li, and Sn composite materials according to claim 1, wherein the reducing agent is thiourea, sodium sulfide, sodium thiosulfate, sodium sulfite or combination. The method for forming a battery anode material having a Ti, Li, and Sn composite material according to claim 1, wherein the one-time heat treatment step further comprises a drying step and a cleaning step, wherein the drying step is It is carried out at 60 ° C ~ 120 ° C.