JP4805691B2 - Non-aqueous electrolyte battery active material, non-aqueous electrolyte battery and battery pack - Google Patents

Description

  The present invention relates to an active material for a lithium ion nonaqueous electrolyte battery, a nonaqueous electrolyte battery, and a battery pack.

  Non-aqueous electrolyte batteries that are charged and discharged by moving lithium ions between a negative electrode and a positive electrode are actively researched and developed as high energy density batteries.

  In recent years, nonaqueous electrolyte batteries have been expected as power sources for uninterruptible power supplies of hybrid vehicles, electric vehicles, mobile phone base stations, etc., and have been promoted in the past, such as long-term reliability of about 3 to 10 years. Different characteristics from high energy density are required.

  In order to improve reliability, the key is to reduce deterioration due to side reactions between the electrolytic solution and the electrode active material. As a method for significantly suppressing the side reaction, increasing the charging potential of the negative electrode can be mentioned. Conventionally, an active material, such as graphite, that undergoes Li desorption reaction at a potential close to the ionization potential of Li metal (0.01 to 0.4 V vs. Li / Li +) has been used for the negative electrode. On the other hand, by using an active material in which the Li desorption reaction is performed at a higher potential (about 0.5 to 2 V vs. Li / Li +) as the negative electrode, the potential of the negative electrode during charging can be increased and the electrolyte solution can be added. The reaction can be made difficult to proceed.

  Oxides such as Li4Ti5O12, TiO2, MoO2, and WO2 can desorb and insert lithium at a potential in the range of 0.4 to 2.5 V vs. Li / Li +, but have insufficient capacity density or cycle characteristics.

  Lithium titanate (Li4Ti5O12) has very high reliability in lithium desorption, but its weight capacity density is only about one-half that of graphite, and it has energy compared to conventional lithium secondary batteries. A decrease in density is inevitable. On the other hand, TiO 2 having a weight capacity density larger than that of lithium titanate, MoO 2 having a large volume capacity density, and WO 2 are all poor in cycle characteristics. In particular, since TiO2 is an insulator, the charge / discharge reaction is difficult to proceed.

  Regarding active materials of TiO2, MoO2, and WO2, improvement of cycle characteristics by adding other metal elements is disclosed (see Patent Documents 1 to 3).

  Patent Document 1 discloses that an active material is synthesized by adding an oxide such as Fe or Ni to anatase TiO2 and baking at 700 ° C. for 10 hours. Patent Document 2 discloses that an active material is synthesized by adding an oxide such as Fe or Ni to MoO2 and baking at 700 ° C. for 12 hours. Patent Document 3 discloses that an active material is synthesized by adding an oxide such as Fe or Ni to WO2 and baking at 1000 ° C. for 10 hours.

However, these active materials have not yet achieved sufficient cycle characteristics.
JP 2000-268822 JP JP 2000-277113 A JP 2000-277111 A

  In view of the above circumstances, the present invention provides an active material excellent in cycle characteristics, and a nonaqueous electrolyte battery and a battery pack using the active material.

  The active material for a non-aqueous electrolyte battery according to the present invention is an M1 metal dioxide oxide selected from Ti, Mo, and W, to which M2 selected from Cr, Fe, Ni, Cu, Zr, Ge, Sn, and Zn is added. In the X-ray diffraction pattern, the full width at half maximum of the peak having the highest intensity is 1 ° or more and less than 4 °.

  In addition, the nonaqueous electrolyte battery of the present invention includes a positive electrode and M1 metal dioxide selected from Ti, Mo, and W, to which M2 selected from Cr, Fe, Ni, Cu, Zr, Ge, Sn, and Zn is added. A negative electrode having an active material that is an oxide and has a peak half-width of 1 ° or more and less than 4 ° in an X-ray diffraction pattern, and a non-aqueous electrolyte is provided.

  Moreover, the battery pack of the present invention is characterized by comprising the above-mentioned assembled battery of nonaqueous electrolyte batteries.

  The present invention provides an active material excellent in cycle characteristics, and a nonaqueous electrolyte battery and a battery pack using the active material.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment, and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for promoting explanation and understanding of the invention, and its shape, dimensions, ratio, and the like are different from those of an actual device. However, these are in consideration of the following explanation and known techniques. The design can be changed as appropriate.

  First, the active material for a nonaqueous electrolyte battery will be described in the first embodiment, then the nonaqueous electrolyte battery will be described in the second embodiment, and finally, the third embodiment will be described. The battery pack will be described.

(First embodiment)
The active material for nonaqueous electrolyte batteries according to the first embodiment will be described.

  The active material for a non-aqueous electrolyte battery according to the first embodiment is an M1 metal oxide selected from Ti, Mo, and W, and includes Cr, Fe, Ni, Cu, Zr, Ge, Sn, and Zn. M2 selected is added to the metal dioxide oxide, and the half-width of the peak having the highest intensity in the X-ray diffraction pattern is 1 ° or more and less than 4 °.

  In the first embodiment, lithium is inserted by reducing the crystal structure by adding M2 to the metal dioxide oxide of M1 selected from Ti, Mo, and W, and manufacturing it by the manufacturing method described later. Destruction of the crystal structure due to desorption can be reduced, and cycle characteristics can be improved.

  This is thought to be because many voids were generated in the structure due to low crystallization, and the resistance to changes in the volume of the crystal lattice due to lithium insertion / extraction increased. Furthermore, it is considered that the additive metal element generates defects, vacancies, and amorphous portions in the crystal structure, and contributes to maintaining the resistance to lithium insertion / extraction of the crystal structure.

  As a secondary effect, the presence of many vacancies in the crystal increases the number of lithium occlusion sites and increases the charge / discharge capacity.

  Note that low crystallization in the present embodiment refers to a state in which the X-ray diffraction pattern is broadened, and is different from an amorphous state in which no peak is visible in the X-ray diffraction pattern. Specifically, low crystallization refers to an active material prepared such that the full width at half maximum of the peak having the highest intensity in the X-ray diffraction pattern is 1 ° or more and less than 4 °.

  Therefore, in the first embodiment, it is important to adjust the full width at half maximum of the strongest diffraction peak in the powder X-ray diffraction measurement of the active material to 1 ° or more and less than 4 °. When it is 1 ° or more, the effect of reducing deterioration due to expansion and contraction of the active material due to low crystallization becomes apparent. If it is less than 4 °, it is difficult to make the cycle deterioration due to side reactions and elution caused by the raw materials remaining due to insufficient firing.

  These additive metal elements also contribute to imparting conductivity to the active material. These additive metal elements are stable as oxides in a potential range of 0.5 to 2 V vs. Li / Li + and do not adversely affect charging and discharging.

  In particular, with regard to titanium dioxide in which M1 is Ti, the conductivity is remarkably improved, and sufficient charge / discharge capacity and cycle characteristics can be obtained in both the anatase type and the rutile type. Therefore, it is preferable to use rutile TiO2 or anatase TiO2 as the main phase. The main phase refers to a phase having the highest intensity diffraction peak in the X-ray diffraction pattern.

  Furthermore, as will be described later in the examples, titanium dioxide having anatase-type TiO2 as a main phase is more effective in improving the cycle characteristics of the first embodiment than titanium dioxide having rutile-type TiO2 as a main phase. Is particularly suitable for the present invention.

  On the other hand, for molybdenum dioxide and tungsten dioxide in which M1 is Mo or W, it is preferable that the crystal phase belonging to the monoclinic system and belonging to the space group P21 / n is the main phase. This is because the reversible storage amount of Li is large and the conductivity of the oxide is high.

  It is important that the active material of the first embodiment is fired at a relatively low temperature in order to prepare the half-width of the peak with the highest intensity in the X-ray diffraction pattern to be 1 ° or more and less than 4 °. is there. The optimum firing temperature varies depending on the additive element M2, and the relationship between the main phase of the metal dioxide oxide and preferred firing conditions is as follows.

Anatase TiO2: 350 ° C to 600 ° C, 2 hours to 20 hours Rutile TiO2: 500 ° C to 1000 ° C, 2 hours to 20 hours
MoO2 · WO2: 400 ° C or higher and 600 ° C or lower, 2 hours or longer and 20 hours or shorter On the other hand, if the firing temperature is high as in Patent Documents 1 to 3, the crystallinity of the active material increases and the half-value width of the X-ray diffraction pattern Cannot be adjusted to the above range, and the effect of improving the cycle characteristics of the present embodiment cannot be expected.

  In this production method, since it takes a long time to obtain a uniform material by in-solid diffusion, the precursor is preferably prepared by mixing or reacting in the liquid phase. A method of obtaining a precursor from an aqueous solution by a coprecipitation method, a method of obtaining a precursor gel containing an additive element by a sol-gel method, and the like are particularly preferable.

  M1 and M2 preferably satisfy a molar ratio of 0.03 ≦ M2 / (M1 + M2) ≦ 0.2. If it is smaller than this range, the effect of improving the cycle characteristics and increasing the capacity may not be sufficient, and if this range is exceeded, the charge / discharge capacity becomes smaller.

  The average particle size of the active material is preferably 20 nm or more and 10 μm or less. The particle size and specific surface area of the active material affect the rate of lithium insertion and desorption reaction, and have a great influence on the negative electrode characteristics. However, values within this range can stably exhibit the characteristics.

  Furthermore, the average particle size of the active material is preferably 1 μm or less. This is for improving the utilization factor of the active material and improving the large current characteristics of the battery.

  As a method for analyzing the average particle diameter of the active material, a laser diffraction method may be mentioned. For example, using a laser diffraction distribution measuring device (Shimadzu SALD-300), first add about 0.1 g of a sample, a surfactant and 1 to 2 mL of distilled water to a beaker and stir well, and then a stirred water tank The luminous intensity distribution is measured 64 times at intervals of 2 seconds, and the particle size distribution data is analyzed.

(Second embodiment)
The nonaqueous electrolyte battery according to the second embodiment is characterized by using the active material of the first embodiment as a negative electrode active material.

  The structure of an example of a single battery (nonaqueous electrolyte battery) according to the second embodiment will be described with reference to FIGS. 1 and 2. In FIG. 1, the cross-sectional schematic diagram of the flat type nonaqueous electrolyte secondary battery concerning 2nd embodiment is shown. FIG. 2 is a partial cross-sectional schematic diagram showing in detail a portion surrounded by a circle shown by A in FIG.

  As shown in FIG. 1, a flat wound electrode group 6 is accommodated in the exterior member 7. The wound electrode group 6 has a structure in which the positive electrode 3 and the negative electrode 4 are wound in a spiral shape with a separator 5 interposed therebetween. The nonaqueous electrolyte is held in the wound electrode group 6.

  As shown in FIG. 2, the negative electrode 4 is located on the outermost periphery of the wound electrode group 6, and the separator 5, the positive electrode 3, the separator 5, the negative electrode 4, the separator 5, and the positive electrode 3 are disposed on the inner peripheral side of the negative electrode 4. The positive electrode 3 and the negative electrode 4 are alternately stacked with the separator 5 interposed therebetween, such as a separator 5. The negative electrode 4 includes a negative electrode current collector 4a and a negative electrode active material-containing layer 4b supported on the negative electrode current collector 4a. In the portion located on the outermost periphery of the negative electrode 4, the negative electrode active material-containing layer 4b is formed only on one surface of the negative electrode current collector 4a. The positive electrode 3 includes a positive electrode current collector 3a and a positive electrode active material-containing layer 3b supported on the positive electrode current collector 3a.

  As shown in FIG. 1, the strip-like positive electrode terminal 1 is electrically connected to the positive electrode current collector 3 a in the vicinity of the outer peripheral end of the wound electrode group 6. On the other hand, the strip-like negative electrode terminal 2 is electrically connected to the negative electrode current collector 4 a in the vicinity of the outer peripheral end of the wound electrode group 6. The tips of the positive electrode terminal 1 and the negative electrode terminal 2 are drawn out from the same side of the exterior member 7.

  Hereinafter, the negative electrode, the nonaqueous electrolyte, the positive electrode, the separator, the exterior member, the positive electrode terminal, and the negative electrode terminal will be described in detail.

1) Negative Electrode The negative electrode includes a negative electrode current collector and a negative electrode layer that is supported on one or both surfaces of the negative electrode current collector and includes a negative electrode active material, a negative electrode conductive agent, and a binder.

  As the negative electrode active material, the active material of the first embodiment described above is used.

  Examples of the negative electrode conductive agent for improving the current collecting performance and suppressing the contact resistance with the current collector include acetylene black, carbon black, and graphite.

  Examples of the binder for binding the negative electrode active material and the negative electrode conductive agent include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene butadiene rubber, and the like.

  The thickness of the negative electrode active material layer is desirably in the range of 1.0 to 150 μm. Therefore, when the negative electrode current collector is supported on both surfaces, the total thickness of the negative electrode active material layer is in the range of 20 to 300 μm. A more preferable range of the thickness of one side is 30 to 100 μm. Within this range, the large current discharge characteristics and cycle life are greatly improved.

  Regarding the mixing ratio of the negative electrode active material, the negative electrode conductive agent, and the binder, the negative electrode active material is 70% by weight to 96% by weight, the negative electrode conductive agent is 2% by weight to 28% by weight, and the binder is 2% by weight. It is preferable to be in the range of 28% by weight or less. When the amount of the negative electrode conductive agent is less than 2% by weight, the current collecting performance of the negative electrode layer is deteriorated, and the large current characteristics of the nonaqueous electrolyte secondary battery are deteriorated. On the other hand, when the amount of the binder is less than 2% by weight, the binding property between the negative electrode layer and the negative electrode current collector is lowered, and the cycle characteristics are lowered. On the other hand, from the viewpoint of increasing the capacity, the negative electrode conductive agent and the binder are each preferably 28% by weight or less.

  The negative electrode current collector is preferably copper, nickel, or stainless steel that is electrochemically stable at the Li insertion / release potential of the negative electrode active material. The thickness of the negative electrode current collector is desirably 5 to 20 μm. This is because within this range, the electrode strength and weight reduction can be balanced.

  The negative electrode is prepared by, for example, applying a slurry prepared by suspending a negative electrode active material, a negative electrode conductive agent, and a binder in a commonly used solvent to a negative electrode current collector, drying the negative electrode layer, and then forming a negative electrode layer. It is produced by applying. In addition, the negative electrode active material, the negative electrode conductive agent, and the binder may be formed in a pellet shape and used as the negative electrode layer.

2) Non-aqueous electrolyte Examples of the non-aqueous electrolyte include a liquid non-aqueous electrolyte prepared by dissolving an electrolyte in an organic solvent, a gel non-aqueous electrolyte obtained by combining a liquid electrolyte and a polymer material, and the like.

  The liquid non-aqueous electrolyte is prepared by dissolving the electrolyte in an organic solvent at a concentration of 0.5 mol / l or more and 2.5 mol / l or less.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), and trifluorometa. Examples thereof include lithium salts such as lithium sulfonate (LiCF ₃ SO ₃ ) and bistrifluoromethylsulfonylimitolithium [LiN (CF ₃ SO ₂ ) ₂ ], or a mixture thereof. It is preferable that it is difficult to oxidize even at a high potential, and LiPF ₆ is most preferable.

  Examples of the organic solvent include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate, and chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). And cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), dioxolane (DOX), chain ethers such as dimethoxyethane (DME) and dietoethane (DEE), γ-butyrolactone (GBL), acetonitrile ( AN), sulfolane (SL) and the like alone or in combination.

  Examples of the polymer material include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), and the like.

  As the nonaqueous electrolyte, a room temperature molten salt (ionic melt) containing lithium ions, a polymer solid electrolyte, an inorganic solid electrolyte, or the like may be used.

  The room temperature molten salt (ionic melt) refers to a compound that can exist as a liquid at room temperature (15 ° C. to 25 ° C.) among organic salts composed of a combination of an organic cation and an anion. Examples of the room temperature molten salt include a room temperature molten salt that exists alone as a liquid, a room temperature molten salt that becomes a liquid when mixed with an electrolyte, and a room temperature molten salt that becomes a liquid when dissolved in an organic solvent. In general, the melting point of a room temperature molten salt used for a nonaqueous electrolyte battery is 25 ° C. or less. The organic cation generally has a quaternary ammonium skeleton.

  The polymer solid electrolyte is prepared by dissolving an electrolyte in a polymer material and solidifying it.

  The inorganic solid electrolyte is a solid material having lithium ion conductivity.

3) Positive Electrode The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer that is supported on one or both surfaces of the positive electrode current collector and includes a positive electrode active material, a positive electrode conductive agent, and a binder.

  Examples of the positive electrode active material include oxides, sulfides, and polymers.

For example, as the oxide, manganese dioxide (MnO ₂ ) occluded Li, iron oxide, copper oxide, nickel oxide, and lithium manganese composite oxide (for example, Li _x Mn ₂ O ₄ or Li _x MnO ₂ ), lithium Nickel composite oxide (for example, Li _x NiO ₂ ), lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel cobalt composite oxide (for example, LiNi _1-y Co _y O ₂ ), lithium manganese cobalt composite oxide (for example, LiMn _y Co _1-y O ₂ ), spinel-type lithium manganese nickel composite oxide (Li _x Mn _2-y Ni _y O ₄ ), lithium phosphorus oxide having an olivine structure (Li _x FePO ₄ , Li _x Fe _{1- y Mn y PO 4, Li x} CoPO 4 , etc.), iron sulfate (Fe ₂ (SO _{4) 3),} vanadium oxide (e.g. V ₂ O _5), and lithium-nickel-cobalt-manganese composite oxide and the like.

  For example, examples of the polymer include conductive polymer materials such as polyaniline and polypyrrole, and disulfide polymer materials. In addition, sulfur (S), carbon fluoride, etc. can be used.

As positive electrode active materials that can obtain a high positive electrode voltage, lithium manganese composite oxide (Li _x Mn ₂ O ₄ ), lithium nickel composite oxide (Li _x NiO ₂ ), lithium cobalt composite oxide (Li _x CoO ₂ ), Lithium nickel cobalt composite oxide (Li _x Ni _1-y Co _y O ₂ ), spinel type lithium manganese nickel composite oxide (Li _x Mn _2-y Ni _y O ₄ ), lithium manganese cobalt composite oxide (Li _x Mn _y Co _1-y O ₂ ), lithium iron phosphate (Li _x FePO ₄ ), lithium nickel cobalt manganese composite oxide, and the like. X and y are preferably in the range of 0 to 1.

Among them, when using a non-aqueous electrolyte containing a room temperature molten salt, it is possible to use lithium iron phosphate, Li _x VPO ₄ F, lithium manganese composite oxide, lithium nickel composite oxide, lithium nickel cobalt composite oxide, It is preferable from the viewpoint of cycle life. This is because the reactivity between the positive electrode active material and the room temperature molten salt is reduced.

  Examples of the positive electrode active material for the primary battery include manganese dioxide, iron oxide, copper oxide, iron sulfide, and carbon fluoride.

  The primary particle diameter of the positive electrode active material is preferably 100 nm or more and 1 μm or less. It is easy to handle in industrial production as it is 100 nm or more. When the thickness is 1 μm or less, diffusion of lithium ions in the solid can proceed smoothly.

The specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more and 10 m ² / g or less. When it is 0.1 m ² / g or more, sufficient lithium ion storage / release sites can be secured. When it is 10 m ² / g or less, it is easy to handle in industrial production, and good charge / discharge cycle performance can be secured.

  Examples of the positive electrode conductive agent for improving the current collecting performance and suppressing the contact resistance with the current collector include carbonaceous materials such as acetylene black, carbon black, and graphite.

  Examples of the binder for binding the positive electrode active material and the positive electrode conductive agent include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

  The thickness of one surface of the positive electrode active material layer is preferably in the range of 1.0 μm to 150 μm from the viewpoint of maintaining the large current discharge characteristics and cycle life of the battery. Accordingly, when the positive electrode current collector is supported on both surfaces, the total thickness of the positive electrode active material layer is desirably in the range of 20 μm to 300 μm. A more preferable range on one side is 30 μm to 120 μm. Within this range, large current discharge characteristics and cycle life are improved.

  Regarding the compounding ratio of the positive electrode active material, the positive electrode conductive agent, and the binder, the positive electrode active material is 80% by weight to 95% by weight, the positive electrode conductive agent is 3% by weight to 18% by weight, and the binder is 2% by weight. It is preferable to be in the range of 17 wt% or less. With respect to the positive electrode conductive agent, the effect described above can be exhibited by being 3% by weight or more, and by being 18% by weight or less, decomposition of the nonaqueous electrolyte on the surface of the positive electrode conductive agent under high temperature storage can be achieved. Can be reduced. When the amount of the binder is 2% by weight or more, sufficient electrode strength can be obtained, and when the amount is 17% by weight or less, the blending amount of the electrode insulator can be reduced and the internal resistance can be reduced.

  For the positive electrode, for example, a positive electrode active material, a positive electrode conductive agent, and a binder are suspended in a suitable solvent, and this suspended slurry is applied to a positive electrode current collector and dried to produce a positive electrode active material-containing layer. Then, it is manufactured by applying a press. In addition, the positive electrode active material, the positive electrode conductive agent, and the binder may be formed in a pellet shape and used as the positive electrode active material-containing layer.

  The positive electrode current collector is preferably an aluminum foil or an aluminum alloy foil.

  The thickness of the aluminum foil and the aluminum alloy foil is 5 μm or more and 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% or more. As the aluminum alloy, an alloy containing elements such as magnesium, zinc and silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% or less.

4) Separator Examples of the separator include a porous film containing polyethylene, polypropylene, cellulose, or polyvinylidene fluoride (PVdF), and a synthetic resin nonwoven fabric. Among these, a porous film made of polyethylene or polypropylene is preferable from the viewpoint of improving safety because it can be melted at a constant temperature to interrupt the current.

5) Exterior member Examples of the exterior member include a laminate film having a thickness of 0.2 mm or less and a metal container having a thickness of 0.5 mm or less. The wall thickness of the metal container is more preferably 0.2 mm or less.

  Examples of the shape include a flat type, a square type, a cylindrical type, a coin type, a button type, a sheet type, and a laminated type. Of course, in addition to a small battery mounted on a portable electronic device or the like, a large battery mounted on a two-wheel to four-wheel automobile or the like may be used.

  The laminate film is a multilayer film composed of a metal layer and a resin layer covering the metal layer. In order to reduce the weight, the metal layer is preferably an aluminum foil or an aluminum alloy foil. The resin layer is for reinforcing the metal layer, and a polymer such as polypropylene (PP), polyethylene (PE), nylon, polyethylene terephthalate (PET), or the like can be used. The laminate film is formed by sealing by heat sealing.

  Examples of the metal container include aluminum or an aluminum alloy. As the aluminum alloy, an alloy containing elements such as magnesium, zinc and silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 1% or less. Thereby, it becomes possible to dramatically improve long-term reliability and heat dissipation in a high temperature environment.

6) Negative electrode terminal The negative electrode terminal can be formed from a material that is electrochemically stable at the Li occlusion-release potential of the negative electrode active material described above and has conductivity. Specific examples include copper, nickel, and stainless steel. In order to reduce the contact resistance, the same material as the negative electrode current collector is preferable.

7) Positive electrode terminal The positive electrode terminal can be formed from a material having electrical stability and electrical conductivity in a range where the potential with respect to the lithium ion metal is 3 V or more and 5 V or less. Specific examples include aluminum alloys and aluminum containing elements such as Mg, Ti, Zn, Mn, Fe, Cu, and Si. In order to reduce the contact resistance, the same material as the positive electrode current collector is preferable.

  The nonaqueous electrolyte battery according to the second embodiment is not limited to the configuration shown in FIGS. 1 and 2 described above, and can be configured, for example, as shown in FIGS. FIG. 3 is a partially cutaway perspective view schematically showing another flat type nonaqueous electrolyte secondary battery according to the second embodiment, and FIG. 4 is an enlarged cross-sectional view of a portion B in FIG.

  As shown in FIG. 3, a laminated electrode group 9 is housed in an exterior member 8 made of a laminate film. As shown in FIG. 4, the stacked electrode group 9 has a structure in which the positive electrodes 3 and the negative electrodes 4 are alternately stacked with separators 5 interposed therebetween. There are a plurality of positive electrodes 3, each including a positive electrode current collector 3 a and a positive electrode active material-containing layer 3 b supported on both surfaces of the positive electrode current collector 3 a. A plurality of negative electrodes 4 are present, each including a negative electrode current collector 4a and a negative electrode active material-containing layer 4b supported on both surfaces of the negative electrode current collector 4a. One side of the negative electrode current collector 4 a of each negative electrode 4 protrudes from the positive electrode 3. The negative electrode current collector 4 a protruding from the positive electrode 3 is electrically connected to the strip-shaped negative electrode terminal 2. The tip of the strip-like negative electrode terminal 2 is drawn out from the exterior member 8 to the outside. Although not shown here, the positive electrode current collector 3a of the positive electrode 3 has a side protruding from the negative electrode 4 on the side opposite to the protruding side of the negative electrode current collector 4a. The positive electrode current collector 3 a protruding from the negative electrode 4 is electrically connected to the belt-like positive electrode terminal 1. The front end of the belt-like positive electrode terminal 1 is located on the opposite side to the negative electrode terminal 2 and is drawn out from the side of the exterior member 8.

(Third embodiment)
The battery pack according to the third embodiment has a plurality of single batteries according to the second embodiment. Each battery unit is electrically arranged in series or in parallel to form an assembled battery.

  The flat battery shown in FIG. 1 or FIG. 3 can be used for a single battery.

  The battery unit 21 in the battery pack of FIG. 5 is composed of a flat type non-aqueous electrolyte battery shown in FIG. The plurality of battery units 21 are stacked in the thickness direction with the direction in which the positive electrode terminal 1 and the negative electrode terminal 2 protrude are aligned. As shown in FIG. 6, the battery units 21 are connected in series to form an assembled battery 22. As shown in FIG. 5, the assembled battery 22 is integrated by an adhesive tape 23.

  A printed wiring board 24 is disposed on the side surface from which the positive electrode terminal 1 and the negative electrode terminal 2 protrude. As shown in FIG. 6, a thermistor 25, a protection circuit 26, and a terminal 27 for energizing external devices are mounted on the printed wiring board 24.

  As shown in FIGS. 5 and 6, the positive electrode side wiring 28 of the assembled battery 22 is electrically connected to the positive electrode side connector 29 of the protection circuit 26 of the printed wiring board 24. The negative electrode side wiring 30 of the assembled battery 22 is electrically connected to the negative electrode side connector 31 of the protection circuit 26 of the printed wiring board 24.

  The thermistor 25 is for detecting the temperature of the battery unit 21, and the detection signal is transmitted to the protection circuit 26. The protection circuit 26 can cut off the plus side wiring 31a and the minus side wiring 31b between the protection circuit and a terminal for energization to an external device under a predetermined condition. The predetermined condition is, for example, when the detected temperature of the thermistor becomes equal to or higher than a predetermined temperature, or when overcharge, overdischarge, overcurrent, or the like of the battery unit 21 is detected. This detection method is performed for each individual battery unit 21 or the entire battery unit 21. When detecting each battery unit 21, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each battery unit 21. In the case of FIG. 6, wiring 32 for voltage detection is connected to each battery unit 21, and a detection signal is transmitted to the protection circuit 26 through these wirings 32.

  In the assembled battery 22, a protective sheet 33 made of rubber or resin is disposed on three side surfaces other than the side surface from which the positive electrode terminal 1 and the negative electrode terminal 2 protrude. Between the side surface from which the positive electrode terminal 1 and the negative electrode terminal 2 protrude and the printed wiring board 24, a block-shaped protection block 34 made of rubber or resin is disposed.

  The assembled battery 22 is stored in a storage container 35 together with the protective sheets 33, the protective blocks 34, and the printed wiring board 24. That is, the protective sheet 33 is disposed on each of the inner side surface in the long side direction and the inner side surface in the short side direction of the storage container 35, and the printed wiring board 24 is disposed on the inner side surface on the opposite side in the short side direction. The assembled battery 22 is located in a space surrounded by the protective sheet 33 and the printed wiring board 24. A lid 36 is attached to the upper surface of the storage container 35.

  In addition, instead of the adhesive tape 23, a heat shrink tape may be used for fixing the assembled battery 22. In this case, protective sheets are arranged on both side surfaces of the assembled battery, the heat shrinkable tube is circulated, and then the heat shrinkable tube is thermally contracted to bind the assembled battery.

  5 and 6 are connected in series, but may be connected in parallel to increase the battery capacity. Of course, the assembled battery packs can be connected in series and in parallel.

  Moreover, the aspect of a battery pack is changed suitably by a use.

  The battery pack of the third embodiment can be used for power sources of digital cameras, vacuum cleaners, two-wheel to four-wheel hybrid electric vehicles, two-wheel to four-wheel electric vehicles, on-board vehicles such as assist bicycles, etc. Can be mentioned. In particular, those in which both cycle characteristics and energy density are desired are preferable. Specifically, those for electric vehicles and vacuum cleaners are suitable.

  Examples will be described below, but the present invention is not limited to the examples described below unless the gist of the present invention is exceeded.

  (Example 1) A mixed solution of 20 g of ethanol and 1 g of water was dropped into a sol-gel reaction solution in which 23 g of titanium tetraisopropoxide, 50 g of ethanol, and 2.4 g of iron chloride (FeCl 2 · H 2 O) were dissolved, and left at room temperature overnight. A gel was obtained. This was dried at 100 ° C. for 12 hours and then calcined in the atmosphere at 400 ° C. for 6 hours to obtain a negative electrode active material powder.

  (Example 2) A negative electrode active material powder of Example 2 was obtained by synthesis in the same manner as in Example 1 except that the firing temperature was 550 ° C.

  Example 3 Synthesis was performed in the same manner as in Example 1 except that 2.3 g of chromium chloride (CrCl2) was added instead of iron chloride to obtain a negative electrode active material powder of Example 3.

  (Example 4) The negative electrode active material powder of Example 4 was synthesized by the same method as Example 1 except that 2.3 g of chromium chloride (CrCl2) was added instead of iron chloride and the firing temperature was 600 ° C. Obtained.

  Example 5 A negative electrode active material powder of Example 5 was obtained by synthesis in the same manner as in Example 1 except that 2.4 g of nickel chloride (NiCl2) was added instead of iron chloride.

  (Example 6) Instead of iron chloride, 2.4 g of nickel chloride (NiCl2) was added, and the sintering temperature was set to 600 ° C. Obtained.

  (Example 7) A negative electrode active material powder of Example 7 was obtained in the same manner as in Example 1 except that 2.4 g of copper chloride (CuCl2) was added instead of iron chloride.

  (Example 8) The negative electrode active material powder of Example 8 was synthesized by the same method as Example 1 except that 2.4 g of nickel chloride (CuCl2) was added instead of iron chloride and the firing temperature was 520 ° C. Obtained.

  Example 9 A negative electrode active material powder of Example 9 was obtained in the same manner as in Example 1 except that 3.6 g of zirconium tetraisopropoxide was added instead of iron chloride.

  (Example 10) The negative electrode active material powder of Example 10 was synthesized by the same method as Example 1 except that 3.6 g of zirconium tetraisopropoxide was added instead of iron chloride and the firing temperature was 600 ° C. Obtained.

  (Example 11) A negative electrode active material powder of Example 11 was obtained in the same manner as in Example 11 except that 3.3 g of germanium tetraisoethoxide was added instead of iron chloride.

  (Example 12) The negative electrode active material powder of Example 12 was synthesized by the same method as Example 1 except that 3.3 gg of germanium tetraisoethoxide was added instead of iron chloride and the firing temperature was 650 ° C. Obtained.

  (Example 13) A negative electrode active material powder of Example 13 was obtained in the same manner as in Example 1 except that 3.1 g of tin chloride (SnCl2) was added instead of iron chloride.

  (Example 14) The negative electrode active material powder of Example 14 was synthesized by the same method as Example 1 except that 3.1 g of tin chloride (SnCl2) was added instead of iron chloride and the firing temperature was 650 ° C. Obtained.

  Example 15 A negative electrode active material powder of Example 15 was obtained in the same manner as in Example 1 except that 2.2 g of zinc chloride (ZnCl2) was added instead of iron chloride.

  (Example 16) The negative electrode active material powder of Example 16 was synthesized by the same method as in Example 1 except that 2.2 g of zinc chloride (ZnCl2) was added instead of iron chloride and the firing temperature was 600 ° C. Obtained.

  (Example 17) A solution of 2.5 g of nickel chloride (NiCl2) in 50 g of ethanol was added to 8 g of MoO2 powder, and wet-mixed in a mortar. This was dried at 100 ° C. for 12 hours and then calcined in an argon stream at 450 ° C. for 18 hours to obtain a negative electrode active material powder of Example 17.

  (Example 18) A solution prepared by dissolving 2.5 g of nickel chloride (NiCl2) in 50 g of ethanol was added to 8 g of WO2 powder, and wet mixed in a mortar. This was dried at 100 ° C. for 12 hours and then calcined in an argon stream at 450 ° C. for 18 hours to obtain a negative electrode active material powder of Example 18.

  (Example 19) A black-gray negative electrode active material powder whose surface was coated with carbon by subjecting the powder synthesized by the same method as in Example 1 to a heat treatment at 400 ° C. for 3 hours in an argon stream containing toluene vapor. Got.

  (Example 20) A black-gray negative electrode active material powder whose surface was coated with carbon by subjecting a powder synthesized by the same method as in Example 9 to a heat treatment at 400 ° C. for 3 hours in an argon stream containing toluene vapor. Got.

  (Example 21) A black-gray negative electrode active material powder whose surface was coated with carbon by subjecting a powder synthesized by the same method as in Example 10 to a heat treatment at 500 ° C. for 3 hours in an argon stream containing toluene vapor. Got.

  (Comparative Example 1) A mixed solution of 20 g of ethanol and 1 g of water was dropped into a sol-gel reaction solution in which 23 g of titanium tetraisopropoxide and 50 g of ethanol were dissolved, and left at room temperature overnight to obtain a gel. This was dried at 100 ° C. for 12 hours and then calcined in the atmosphere at 400 ° C. for 6 hours to obtain a negative electrode active material powder of Comparative Example 1.

  (Comparative Example 2) Synthesis was performed in the same manner as in Comparative Example 1 except that the firing temperature was set to 700 ° C, whereby an active material of Comparative Example 2 was obtained.

  (Comparative Example 3) The active material of Comparative Example 3 was synthesized in the same manner as in Comparative Example 1 except that 2.4 g of iron chloride FeCl2 · H2O) was dissolved in the sol-gel reaction solution of Comparative Example 1 and the calcination temperature was 700 ° C. Obtained.

  (Comparative Example 4) The active material of Comparative Example 4 was obtained by synthesizing in the same manner as Comparative Example 1 except that 2.4 g of copper chloride (CuCl2) was dissolved in the sol-gel reaction solution of Comparative Example 1 and the calcination temperature was 700 ° C. It was.

  (Comparative Example 5) A negative electrode active material powder of Comparative Example 5 was obtained by synthesizing in the same manner as Comparative Example 1 except that the firing temperature was 250 ° C.

  Comparative Example 6 Commercially available MoO2 powder (300 mesh, 99.5%) was used as the active material.

  (Comparative Example 7) Commercially available WO2 powder (100mesh, 99.9%) was used as the active material.

  (Comparative Example 8) A negative electrode active material powder of Comparative Example 5 was obtained in the same manner as in Comparative Example 1 except that the firing temperature was 350 ° C.

  The samples obtained in Examples 1 to 21 and Comparative Examples 1 to 8 were subjected to composition analysis, X-ray diffraction measurement, and charge / discharge test described below.

(Composition analysis)
Elemental composition of the obtained sample was examined by ICP emission analysis.

(X-ray diffraction measurement)
The obtained powder sample was subjected to powder X-ray diffraction measurement, and the full width at half maximum of the strongest peak of the active material was measured. The measurement was performed under the following conditions using an X-ray diffractometer (model M18XHF22) manufactured by Mac Science Co., Ltd.

Counter cathode: Cu
Tube voltage: 50 kv
Tube current: 300mA
Scanning speed: 1 ° (2θ) / min
Time constant: 1 sec
Receiving slit: 0.15mm
Divergent slit: 0.5 °
Scattering slit: 0.5 °
From the diffraction pattern, the half width (° (2θ)) of the peak of the Si surface index (220) appearing at d = 1.92 ° (2θ = 47.2 °) was measured. Further, when the peak of Si (220) overlapped with the peaks of other substances contained in the active material, the peak was isolated and the half width was measured.

  About the measured diffraction pattern, the background was removed and the influence of the Kα2 line was corrected, and the half width (° (2θ)) of the target peak was measured.

(Charge / discharge test)
The obtained sample was kneaded with N-methylpyrrolidone as a dispersion medium with 7 wt% of graphite having an average diameter of 6 µm and 3 wt% of polyvinylidene fluoride. It was vacuum-dried for 12 hours to obtain a test electrode. A battery in which the counter electrode and the reference electrode were metallic Li and the electrolyte was an EC / MEC (volume ratio 1: 2) solution of 1M LiPF ₆ was produced in an argon atmosphere.

The charge / discharge test conditions were as follows: charging at a current density of 1 mA / cm ² up to a predetermined potential difference (charging potential) between the reference electrode and the test electrode, followed by constant voltage charging for 8 hours, and discharging at a current of 1 mA / cm ² . The process was performed at a density up to a predetermined discharge potential.

  In the charge / discharge test, the charge capacity and the discharge capacity were the amounts of electricity that flowed from the start to the end of charging or discharging. This discharge capacity is defined as the initial discharge capacity.

Next, similarly, the battery is charged to a predetermined charging potential at a current density of 1 mA / cm ² , further subjected to constant voltage charging for 8 hours, and discharged 100 times to a discharging potential at a current density of 10 mA / cm ^2. The maintenance rate of the discharge capacity at the 100th cycle relative to the cycle was measured.

Table 1 shows the results of composition analysis, X-ray diffraction measurement, and charge / discharge test for each example and comparative example.

  As shown in Table 1, Examples 1-21 are excellent in capacity retention after 100 cycles as compared with Comparative Examples 1-8. Therefore, it can be seen that the active material of the present embodiment is excellent in cycle characteristics.

  Further, Example 19 is superior to Example 1, Example 20 is superior to Example 9, and Example 21 is superior to Example 10 in capacity retention after 100 cycles. Therefore, it can be seen that when the surface of the metal dioxide oxide of the present embodiment is coated with carbon, the cycle characteristics are more excellent.

  Further, with respect to the capacity retention rate after 100 cycles, Example 1 is about four times that of Comparative Example 1, whereas Example 2 is about twice that of Comparative Example 2. Therefore, it can be seen that titanium dioxide having an anatase type TiO2 as a main phase has a remarkable effect of improving cycle characteristics as compared with titanium dioxide having a rutile type TiO2 as a main phase, and is particularly suitable for the present invention.

  In Comparative Example 8, the initial charge / discharge capacity is low because impurities (alcohol content, moisture, carbon, etc.) in the reaction liquid remain because the firing temperature is low (350 ° C.), and side reactions occur during Li charging. This is considered to occur.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to these, In the category of the summary of the invention as described in a claim, it can change variously. In addition, the present invention can be variously modified without departing from the scope of the invention in the implementation stage. Furthermore, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

The cross-sectional schematic diagram of the flat type nonaqueous electrolyte secondary battery concerning 1st embodiment. The partial cross section schematic diagram showing in detail the part enclosed by the circle | round | yen shown by A of FIG. The partial notch perspective view which showed typically another flat type nonaqueous electrolyte secondary battery concerning 1st embodiment. The expanded sectional view of the B section of FIG. The disassembled perspective view of the battery pack which concerns on 2nd embodiment. The block diagram which shows the electric circuit of the battery pack of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Positive electrode terminal, 2 ... Negative electrode terminal, 3 ... Positive electrode, 3a ... Positive electrode collector, 3b ... Positive electrode active material containing layer, 4 ... Negative electrode, 4a ... Negative electrode collector, 4b ... Negative electrode active material containing layer, 5 ... Separator, 6 ... wound electrode group, 7, 8 ... exterior member, 9 ... laminated electrode group, 21 ... single battery, 22 ... assembled battery, 23 ... adhesive tape, 24 ... printed wiring board, 28 ... positive electrode side wiring, 29 ... positive electrode side connector, 30 ... negative electrode side wiring, 31 ... negative electrode side connector, 33 ... protective block, 35 ... storage container, 36 ... lid.

Claims (6)

M1 metal oxide selected from Ti, Mo, W, to which M2 selected from Cr, Fe, Ni, Cu, Zr, Ge, Sn, Zn is added,
An active material for a non-aqueous electrolyte battery, wherein a half-width of a peak having the highest intensity in an X-ray diffraction pattern is 1 ° or more and less than 4 °.   2. The active material for a non-aqueous electrolyte battery according to claim 1, wherein the M 1 is Ti and the main phase is rutile TiO 2.   2. The active material for a non-aqueous electrolyte battery according to claim 1, wherein the M 1 is Ti and the main phase is anatase TiO 2.   4. The active material for a non-aqueous electrolyte battery according to claim 1, wherein the molar ratio of M1 and M2 satisfies 0.03 ≦ M2 / (M1 + M2) ≦ 0.2. A positive electrode;
A negative electrode comprising the active material according to any one of claims 1 to 4,
A nonaqueous electrolyte battery comprising: a nonaqueous electrolyte.   A battery pack comprising the assembled battery of the nonaqueous electrolyte battery according to claim 5.

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