JP2016085893A - Active material, electrode, battery cell, lithium ion secondary battery and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a lithium ion secondary battery with a large capacity; or a lithium ion secondary battery enhanced in cycle characteristics.SOLUTION: An active material comprises: particles having lithium, manganese, oxygen and nickel. The particles have a layered rock salt type crystal structure region. The crystal region has a lamination defect. Using an electrode including as an active material, a material having a lamination defect in its layered rock salt type crystal structure region for a lithium ion secondary battery enables the increase in discharge capacity, and the enhancement of battery cycle characteristics involved with charge and discharge thereof.SELECTED DRAWING: Figure 1

Description

The present invention relates to an object, a method, or a manufacturing method. Or this invention relates to a process, a machine, a manufacture, or a composition (composition of matter). In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a battery cell, a power storage device, a memory device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to a structure of a secondary battery and a manufacturing method thereof. In particular, the present invention relates to a positive electrode active material for a lithium ion secondary battery.

In recent years, portable electronic devices such as smartphones and tablets have rapidly spread. In addition, due to increasing interest in environmental issues, attention is focused on hybrid cars and electric vehicles, and the importance of secondary batteries is increasing. Examples of the secondary battery include a nickel metal hydride battery, a lead storage battery, and a lithium ion secondary battery. In particular, lithium ion secondary batteries have been actively developed because of their high capacity and miniaturization.

The basic configuration of the secondary battery is such that an electrolyte (electrolytic solution or solid electrolyte) is interposed between the positive electrode and the negative electrode. As the positive electrode and the negative electrode, a structure having a current collector and an active material layer provided on the current collector is typical. In the case of a lithium ion secondary battery, a material capable of inserting and extracting lithium is used as an active material for the positive electrode and the negative electrode.

In the lithium ion secondary battery, as the positive electrode active material, for example, lithium iron phosphate (LiFePO ₄ ), lithium manganese phosphate (LiMnPO ₄ ), lithium lithium cobalt phosphate (LiCoPO ₄ ), which are disclosed in Patent Document 1, Known are phosphoric acid compounds having an olivine structure including lithium (Li) and iron (Fe), manganese (Mn), cobalt (Co) or nickel (Ni), such as lithium nickel phosphate (LiNiPO ₄ ). Yes.

JP-A-11-259593

An object of one embodiment of the present invention is to provide a novel active material, a novel electrode, a battery cell with large capacity, or a novel power storage device. Another object of one embodiment of the present invention is to provide a power storage device with improved cycle characteristics. Another object of one embodiment of the present invention is to provide a highly reliable power storage device. Another object of one embodiment of the present invention is to provide a power storage device with a long lifetime.

Another object of one embodiment of the present invention is to increase the productivity of a power storage device. Another object of one embodiment of the present invention is to provide a novel power storage device, a novel electrode, a novel active material, or the like.

Note that the description of these problems does not disturb the existence of other problems. Note that one embodiment of the present invention does not necessarily have to solve all of these problems. Issues other than these will be apparent from the description of the specification, drawings, claims, etc., and other issues can be extracted from the descriptions of the specification, drawings, claims, etc. It is.

In one embodiment of the present invention, particles including lithium, manganese, oxygen, and nickel, the particles have a layered rock salt type crystal structure region, and the crystal region has stacking faults Provide active material.

In one embodiment of the invention, the stacking fault is observed using an atomic resolution analytical electron microscope JEM-ARM200F manufactured by JEOL Ltd.

In one embodiment of the present invention, an electrode including an active material layer containing an active material, a conductive additive, and a binder, and a current collector is provided.

In one embodiment of the above invention, the first electrode including an active material and the second electrode are included, and the first electrode has a function of operating as one of a positive electrode and a negative electrode, The two electrodes provide a battery cell having a function capable of operating as the other of the positive electrode and the negative electrode.

In one embodiment of the present invention, a lithium ion secondary battery including a battery cell and a battery control unit is provided.

In one embodiment of the present invention, an electronic device including a lithium ion secondary battery and a display device, operation buttons, an external connection port, a speaker, or a microphone is provided.

According to one embodiment of the present invention, a novel active material, a novel electrode, a power storage device with a large capacity, or a novel power storage device can be provided. According to one embodiment of the present invention, a power storage device with improved cycle characteristics can be provided. According to one embodiment of the present invention, a highly reliable power storage device can be provided. According to one embodiment of the present invention, a power storage device with a long lifetime can be provided.

Further, according to one embodiment of the present invention, productivity of the power storage device can be increased. According to one embodiment of the present invention, a novel power storage device, a novel electrode, a novel active material, or the like can be provided. Note that the description of these effects does not disturb the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. It should be noted that the effects other than these are naturally obvious from the description of the specification, drawings, claims, etc., and it is possible to extract the other effects from the descriptions of the specification, drawings, claims, etc. It is.

It shows the crystal structure of Li ₂ MnO ₃ (rock salt layered type). It shows the crystal structure of Li ₂ MnO ₃ (rock salt layered type). The schematic diagram which shows an electrode. The figure explaining a thin storage battery. The figure explaining sectional drawing of an electrode. The figure explaining a thin storage battery. The figure explaining a thin storage battery. The figure explaining a thin storage battery. The figure explaining the curvature radius of a surface. The figure explaining the curvature radius of a film. The figure explaining a coin type storage battery. The figure explaining a cylindrical storage battery. The figure for demonstrating the example of a storage battery. The figure for demonstrating the example of a storage battery. The figure for demonstrating the example of a storage battery. The figure for demonstrating the example of a storage battery. The figure for demonstrating the example of a storage battery. FIG. 10 is a block diagram illustrating one embodiment of the present invention. 1 is a conceptual diagram illustrating one embodiment of the present invention. FIG. 10 is a circuit diagram illustrating one embodiment of the present invention. FIG. 10 is a circuit diagram illustrating one embodiment of the present invention. 1 is a conceptual diagram illustrating one embodiment of the present invention. FIG. 10 is a block diagram illustrating one embodiment of the present invention. 6 is a flowchart illustrating one embodiment of the present invention. 10A and 10B each illustrate an example of an electronic device. 10A and 10B each illustrate an example of an electronic device. 10A and 10B each illustrate an example of an electronic device. 10A and 10B each illustrate an example of an electronic device. The figure which shows the cross-sectional TEM observation result of lithium manganese complex oxide. The figure which shows the discharge capacity accompanying discharge.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that modes and details can be variously changed. In addition, the present invention is not construed as being limited to the description of the embodiments below.

(Embodiment 1)
In this embodiment, an active material and a manufacturing method thereof according to one embodiment of the present invention will be described with reference to FIGS.

The active material according to one embodiment of the present invention includes particles having stacking faults, and the particles having stacking faults include at least lithium, manganese, nickel, and oxygen.

Note that an active material refers only to a material related to insertion / extraction of ions serving as carriers. However, in this specification and the like, a layer containing carbon covered with an original “active material” is also included.

As one of particles having a layered rock salt type crystal structure having a stacking fault, a lithium manganese composite oxide represented by a composition formula Li _x Mn _y M _z O _w can be given. Therefore, by using the lithium-manganese composite oxide represented by the compositional formula _{Li x Mn y M z O w} , is described a method for synthesizing an active material.

Here, Ni is preferably used as the element M, but a metal element selected from other than lithium and manganese, or silicon and phosphorus may be used. Moreover, it is preferable that 0 ≦ x / (y + z) <2 and z> 0 and 0.26 ≦ (y + z) / w <0.5 are satisfied. Note that the lithium manganese composite oxide means an oxide containing at least lithium and manganese, such as chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, silicon, And at least one element selected from the group consisting of phosphorus and the like. The lithium manganese composite oxide may have a spinel crystal structure region in addition to the layered rock salt crystal structure as long as it has a layered rock salt crystal structure region containing stacking faults. The lithium manganese composite oxide preferably has an average particle size of, for example, 5 nm or more and 50 μm or less.

In this specification and the like, the crystal structure of the layered rock salt is a crystal structure in which a lithium layer and a layer containing lithium and a metal atom are alternately stacked with an oxygen layer interposed therebetween, that is, a metal through an oxide. A crystal structure in which atoms and lithium-containing layers and lithium single layers are alternately stacked.

In this specification and the like, the stacking fault refers to a planar lattice defect (plane defect). In other words, the crystal is formed by periodically stacking several types of atomic planes, but the regularity (order) of the stacking is out of order.

For example, a typical Li ₂ MnO ₃ crystal structure as a layered rock salt crystal structure is shown in FIGS. In this specification, the crystal structure database ICSD No. It is described along the crystal structure of JCPDS 84-1634 by 202639, or ICDD (The International Center for Diffraction Data).

FIG. 1A shows a structure of the crystal structure of Li ₂ MnO ₃ as viewed from [100]. FIG. 2A shows the structure of Li ₂ MnO ₃ as viewed from [110]. FIGS. 1B and 2B show a structure of the layer 23 containing lithium and manganese as viewed from [103].

As shown in FIG. 1A, lithium layers 20 and lithium and manganese layers 21 are alternately stacked in the c-axis direction with an oxygen layer 22 interposed therebetween. As shown in FIG. 1B, lithium 15, manganese 13, and manganese 11 are located on a straight line B parallel to the straight line A, and the straight line A is composed of lithium 10, manganese 12, and manganese 14. .

Similarly, in FIG. 2, as shown in FIG. 2A, lithium layers 20 and lithium and manganese layers 21 are alternately stacked in the c-axis direction with the oxygen layer 22 interposed therebetween. . As shown in FIG. 2B, lithium 16, manganese 11, and manganese 12 are located on a straight line D parallel to the straight line C, and the straight line C is composed of lithium 10, manganese 13, and manganese 17. .

In the crystal structure of Li ₂ MnO _3, the layer having lithium and manganese is laminated with the upper layer or the lower layer 23 having lithium and manganese while being shifted in the ab plane while maintaining the structure, respectively. Stacking faults occur. In other words, if normal, the lithium 10 of the layer 23 containing lithium and manganese is stacked so that the portion that should overlap the lithium of the layer 21 containing lithium and manganese overlaps with manganese along the [001] direction. It becomes a stacking fault.

Since the crystal structure of the layered rock salt is a two-dimensional structure, charging and discharging are performed by diffusion, insertion and desorption of lithium ions while maintaining the layered structure formed by the oxygen layer 22 and the layer 21 containing lithium and manganese. Is done.

However, in the case of the crystal structure of Li ₂ MnO ₃ , lithium ions are released not only from the lithium layer 20 but also from the lithium and manganese layer 21, so that the lithium and manganese layer 21 and the upper and lower layers. The layered structure between the layer 23 having lithium and manganese and the layer 24 having lithium and manganese that are overlapped collapses, and the interlayer distance or the crystal structure itself changes. As a result, diffusion of lithium ions becomes difficult, causing a decrease in battery voltage and a decrease in discharge capacity.

On the other hand, when the lithium manganese composite oxide has a stacking fault in the layered rock salt type crystal structure region, a metal atom enters the stacking fault. Therefore, when lithium ions are released from the lithium layer 20 and the layer 21 containing lithium and manganese, the metal atoms that have entered the stacking faults are combined with surrounding oxygen atoms, thereby improving the structural stability of the crystal. The layered structure can be maintained even after lithium ions are desorbed. As a result, diffusion of lithium ions is facilitated, and a decrease in battery voltage and a decrease in discharge capacity can be prevented. Thereby, the cycling characteristics of the battery accompanying charging / discharging can be improved.

Moreover, when the amount of metal atoms of the lithium manganese composite oxide is too large, excessive metal atoms enter the layered rock salt type crystal structure region, thereby inhibiting the diffusion, insertion and desorption of lithium ions. Therefore, in the lithium manganese composite oxide, the molar ratio of manganese to metal atoms is 0.2 to 1.3, preferably 0.2 to 0.5, and more preferably 0.2 to 0.5, with respect to 1 for manganese. What should be done.

As a raw material for the lithium manganese composite oxide, a manganese compound and a lithium compound can be used. Further, together with the raw materials of the manganese compound and the lithium compound, at least one selected from the group consisting of chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, silicon, and phosphorus The raw material of the compound containing these elements can be used. Examples of manganese compounds that can be used include manganese dioxide, manganese sesquioxide, trimanganese tetroxide, hydrated manganese oxide, manganese carbonate, and manganese nitrate. Moreover, as a lithium compound, lithium hydroxide, lithium carbonate, lithium nitrate etc. can be used, for example.

In this embodiment, MnCO _{3 is} used as a manganese compound, Li ₂ CO ₃ and NiO are used as starting materials as a lithium compound.

First, Li ₂ CO ₃ , MnCO ₃ and NiO are used as starting materials, and each is weighed.

Next, Li ₂ CO ₃ , MnCO ₃ , and NiO are mixed. There is no restriction | limiting in particular about the mixing method of a starting material, A well-known crusher and a grinder can be used. Examples thereof include a ball mill, a bead mill, a jet mill, and a roller mill. Further, the pulverization / pulverization method may be dry or wet. There is no restriction | limiting in particular as a solvent which can be used in the case of wet, For example, water, alcohol, acetone, etc. can be used.

When the starting materials are mixed in a wet process, a heat treatment for evaporating the solvent contained in the mixed starting materials is performed. The heat treatment performed here may be performed at 50 ° C. or higher and 150 ° C. or lower. By performing the heat treatment, the solvent contained in the mixed starting material is evaporated to obtain a mixed material.

Next, the mixed raw material is put into a crucible and fired at 800 ° C. or higher and 1100 ° C. or lower. The firing time is, for example, 5 hours to 20 hours, Air gas (dry air) is used as the firing gas, and the flow rate is 10 L / min. The firing atmosphere may be an air atmosphere or an atmosphere using oxygen gas. A fired product (lithium manganese composite oxide) is formed by firing the mixed raw material.

The lithium manganese composite oxide obtained by sintering a plurality of primary particles synthesized by firing is in a state in which a large number of primary particles are formed by sintering a plurality of primary particles. Therefore, crushing treatment is performed on the lithium manganese composite oxide in which a plurality of primary particles are sintered. By crushing the fired product, the fired product is crushed into primary particles or into a powder close to primary particles. In the present specification and the like, the crushing treatment includes an operation of crushing the sintered product. In addition, grinding | pulverization means operation which further crushes a primary particle. For the pulverization treatment, a known pulverizer or pulverizer can be used in the same manner as the starting material mixing method. Further, the pulverization / pulverization method may be dry or wet. There is no restriction | limiting in particular as a solvent which can be used in the case of wet, For example, water, alcohol, acetone, etc. can be used. It is preferable to crush the lithium manganese composite oxide because the specific surface area of the particles increases.

In the present embodiment, the pulverization treatment of the lithium manganese composite oxide obtained by sintering the primary particles is performed by a wet method using acetone using a bead mill.

When performing the pulverization treatment, when performing the pulverization treatment, heat treatment for evaporating the solvent is performed after the pulverization treatment. The heat treatment performed here may be performed under the same conditions as in the baking step. Thereafter, vacuum drying is performed to obtain a powdery lithium manganese composite oxide.

The lithium manganese composite oxide after the crushing treatment may be disturbed in crystallinity due to the impact of the crushing treatment. In addition, oxygen deficiency may occur in the lithium manganese composite oxide. Therefore, it is preferable to heat-treat again the powdery lithium manganese composite oxide after vacuum drying.

In the heat treatment, the crushed lithium manganese composite oxide is put in a crucible, and the heat treatment is performed at 300 ° C. to 1000 ° C., preferably 600 ° C. to 900 ° C. The heating time is, for example, 5 hours to 20 hours, Air gas (dry air) is used as the gas, and the flow rate is 10 L / min. The heating atmosphere may be an air atmosphere or an atmosphere using oxygen gas.

By performing heat treatment on the lithium manganese composite oxide after the pulverization treatment, the oxygen deficiency can be repaired and the disorder of crystallinity during the pulverization treatment can be recovered. In addition, the powdered lithium manganese composite oxide after the heat treatment may be crushed again, and in this case, the pulverization treatment is performed by the lithium manganese composite oxide in which primary particles are sintered. What is necessary is just to perform on the conditions similar to the crushing process performed with respect to.

Through the above steps, a lithium manganese composite oxide having a layered rock salt type crystal structure region represented by the composition formula Li _x Mn _y M _z O _w and having stacking faults can be formed.

Note that one embodiment of the present invention is described in this embodiment. Alternatively, in another embodiment, one embodiment of the present invention will be described. Note that one embodiment of the present invention is not limited thereto. That is, in this embodiment and other embodiments, various aspects of the invention are described; therefore, one embodiment of the present invention is not limited to a particular aspect. For example, as an embodiment of the present invention, an example in which the active material includes particles having stacking faults is described; however, one embodiment of the present invention is not limited thereto. Depending on circumstances or conditions, in one embodiment of the present invention, the active material may include another particle. Alternatively, for example, depending on circumstances or circumstances, in one embodiment of the present invention, the active material may have another defect. Alternatively, for example, depending on circumstances or conditions, in one embodiment of the present invention, the active material may not include particles having stacking faults.

This embodiment can be implemented in appropriate combination with any of the other embodiments.

(Embodiment 2)
In this embodiment, an electrode and a manufacturing method thereof according to one embodiment of the present invention will be described.

<Electrode configuration>
3A is an overhead view of the electrode 100, and FIG. 3B is a view showing a cross section of a portion surrounded by a broken line in FIG. 3A. The electrode 100 has a structure in which an active material layer 102 is provided over a current collector 101. Note that FIG. 3A illustrates an example in which the active material layer 102 is provided on both surfaces of the current collector 101; however, the active material layer 102 may be provided only on one surface of the current collector 101.

The current collector 101 is not particularly limited as long as it exhibits high conductivity without causing a significant chemical change in the battery cell. For example, metals such as stainless steel, gold, platinum, zinc, iron, nickel, copper, aluminum, titanium, tantalum, and manganese, alloys thereof, sintered carbon, and the like can be used. Further, copper or stainless steel may be coated with carbon, nickel, titanium or the like. Alternatively, an aluminum alloy to which an element that improves heat resistance, such as silicon, neodymium, scandium, or molybdenum, is added can be used. Alternatively, a metal element that forms silicide by reacting with silicon may be used. Examples of metal elements that react with silicon to form silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, and the like. In addition, the current collector 101 has various shapes such as a foil shape, a plate shape (sheet shape), a net shape, a columnar shape, a coil shape, a punching metal shape, an expanded metal shape, a porous shape, and a nonwoven fabric as appropriate. Can be used. Furthermore, the current collector 101 may have fine irregularities on the surface in order to increase the adhesion with the active material layer. The current collector 101 may have a thickness of 5 μm to 30 μm.

The active material layer 102 includes an active material. An active material refers only to a substance related to insertion / extraction of ions serving as carriers, but in this specification and the like, in addition to a material that is originally an “active material”, a material that includes a conductive assistant or a binder. Is also called an active material layer.

When the negative electrode active material is used as the active material, for example, a carbon-based material, an alloy-based material, or the like can be used.

Examples of the carbon-based material include graphite, graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotube, graphene, and carbon black.

Examples of graphite include artificial graphite such as mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite, and natural graphite such as spheroidized natural graphite.

Graphite shows a base potential as low as lithium metal when lithium ions are inserted into the graphite (when a lithium graphite intercalation compound is formed) (0.1 to 0.3 V vs. Li ^/ Li ⁺ ). Thereby, a lithium ion secondary battery can show a high operating voltage. Further, graphite is preferable because it has advantages such as relatively high capacity per unit volume, small volume expansion, low cost, and high safety compared to lithium metal.

As the negative electrode active material, a material capable of performing a charge / discharge reaction by an alloying / dealloying reaction with lithium can also be used. For example, a material containing at least one of Ga, Si, Al, Ge, Sn, Pb, Sb, Bi, Ag, Zn, Cd, In, and the like can be used. Such an element has a larger capacity than carbon. In particular, silicon has a high theoretical capacity of 4200 mAh / g. Examples of alloy materials using such elements include Mg ₂ Si, Mg ₂ Ge, Mg ₂ Sn, SnS ₂ , V ₂ Sn ₃ , FeSn ₂ , CoSn ₂ , Ni ₃ Sn ₂ , and Cu ₆ Sn _5. , Ag ₃ Sn, Ag ₃ Sb, Ni ₂ MnSb, CeSb ₃ , LaSn ₃ , La ₃ Co ₂ Sn ₇ , CoSb ₃ , InSb, SbSn, and the like.

As the negative electrode active material, SiO, SnO, SnO ₂ , titanium dioxide (TiO ₂ ), lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ ), lithium graphite intercalation compound, (Li _x C ₆ ), niobium pentoxide ( An oxide such as Nb ₂ O ₅ ), tungsten oxide (WO ₂ ), or molybdenum oxide (MoO ₂ ) can be used.

Further, as the anode active material, a double nitride of lithium and a transition metal, Li ₃ with N-type structure _{Li 3-x M x N (} M = Co, Ni, Cu) can be used. For example, Li _2.6 Co _0.4 N ₃ shows a large charge / discharge capacity (900 mAh / g, 1890 mAh / cm ³ ) and is preferable.

When lithium and transition metal double nitride is used, since the negative electrode active material contains lithium ions, it can be combined with materials such as V ₂ O ₅ and Cr ₃ O ₈ that do not contain lithium ions as the positive electrode active material. . Note that even when a material containing lithium ions is used for the positive electrode active material, lithium and transition metal double nitride can be used as the negative electrode active material by previously desorbing lithium ions contained in the positive electrode active material.

A material that causes a conversion reaction can also be used as the negative electrode active material. For example, a transition metal oxide that does not undergo an alloying reaction with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), or iron oxide (FeO), may be used as the negative electrode active material. As a material causing the conversion reaction, oxides such as Fe ₂ O ₃ , CuO, Cu ₂ O, RuO ₂ and Cr ₂ O ₃ , sulfides such as CoS _0.89 , NiS and CuS, Zn ₃ N _{2 are further included.} This also occurs in nitrides such as Cu ₃ N and Ge ₃ N ₄ , phosphides such as NiP ₂ , FeP ₂ and CoP ₃ , and fluorides such as FeF ₃ and BiF ₃ .

When a positive electrode active material is used as the active material, a material into which lithium ions can be inserted and removed can be used. For example, a material having an olivine structure, a layered rock salt structure, a spinel structure, a NASICON crystal structure, or the like can be used.

In this embodiment, the case where the active material described in Embodiment 1 is used as the positive electrode active material will be described; however, other active materials may be used.

Examples of the active material other than the active material described in the first embodiment include LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , Li ₂ NiO ₃ , LiMn ₂ O ₄ , V ₂ O ₅ , Cr ₂ O ₅ , and MnO _2. Etc. can be used as materials.

Alternatively, an olivine-type lithium-containing composite phosphate (general formula LiMPO ₄ (M is one or more of Fe (II), Mn (II), Co (II), Ni (II))) can be used. . Representative examples of the general formula LiMPO ₄ include LiFePO ₄ , LiNiPO ₄ , LiCoPO ₄ , LiMnPO ₄ , LiFe _a Ni _b PO ₄ , LiFe _a Co _b PO ₄ , LiFe _a Mn _b PO ₄ , LiNi _a Co _b PO ₄ . LiNi _a Mn _b PO ₄ (a + b is 1 or less, 0 <a <1, 0 <b <1), LiFe _c Ni _d Co _e PO ₄ , LiFe _c Ni _d M _e PO ₄ , LiNi _c Co _d Mn _e PO ₄ (c + d + e ≦ _{1, 0 <c <1,0 <d} <1,0 <e <1), LiFe f Ni g Co h Mn i PO 4 (f + g + h + i is 1 or less, 0 <f <1,0 < Examples thereof include lithium metal phosphate compounds such as g <1, 0 <h <1, 0 <i <1).

Or a lithium-containing composite such as a general formula Li _(2-j) MSiO ₄ (M is one or more of Fe (II), Mn (II), Co (II), Ni (II), 0 ≦ j ≦ 2) Silicates can be used. Representative examples of the general formula Li _(2-j) MSiO ₄ include Li _(2-j) FeSiO ₄ , Li _(2-j) NiSiO ₄ , Li _(2-j) CoSiO ₄ , Li _(2-j) MnSiO _{4, Li (2-j)} Fe k Ni l SiO 4, Li (2-j) Fe k Co l SiO 4, Li (2-j) Fe k Mn l SiO 4, Li (2-j) Ni k Co _{l SiO 4, Li (2-} j) Ni k Mn l SiO 4 (k + l is 1 or _{less, 0 <k <1,0 <l} <1), Li (2-j) Fe m Ni n Co q SiO 4, _{Li (2-j) Fe m} Ni n Mn q SiO 4, Li (2-j) Ni m Co n Mn q SiO 4 (m + n + q is 1 or less, 0 <m <1,0 <n <1,0 <q _{<1), Li (2-} j) Fe r Ni s Co t Mn _{u SiO 4 (r + s +} t + u ≦ 1, 0 <r <1,0 <s <1,0 <t <1,0 <u <1) lithium silicate compounds of the like.

As active materials, A _x M ₂ (XO ₄ ) ₃ (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb, Al, X = S, P, Mo, W, As, A NASICON type compound represented by the general formula of Si) can be used. Examples of NASICON compounds include Fe ₂ (MnO ₄ ) ₃ , Fe ₂ (SO ₄ ) ₃ , and Li ₃ Fe ₂ (PO ₄ ) ₃ . Further, as a positive electrode active material, a compound represented by a general formula of Li ₂ MPO ₄ F, Li ₂ MP ₂ O ₇ , Li ₅ MO ₄ (M = Fe, Mn), a perovskite type fluoride such as NaF ₃ , FeF _3, etc. , Metal chalcogenides such as TiS ₂ and MoS ₂ (sulfides, selenides, tellurides), materials having an inverse spinel crystal structure such as LiMVO ₄ , vanadium oxides (V ₂ O ₅ , V ₆ O ₁₃ , LiV ₃ O _{8 and the} like), manganese oxide, organic sulfur compounds, and the like can be used.

When the carrier ion is an alkali metal ion or alkaline earth metal ion other than lithium ion, lithium is used as the positive electrode active material in the lithium compound, lithium-containing composite phosphate and lithium-containing composite silicate. A compound substituted with a carrier such as a metal (for example, sodium or potassium) or an alkaline earth metal (for example, calcium, strontium, barium, beryllium, magnesium) may be used.

The average particle diameter of the positive electrode active material is preferably, for example, 5 nm or more and 50 μm or less.

The active material layer 102 may have a conductive additive. As the conductive assistant, for example, artificial graphite such as natural graphite or mesocarbon microbeads, carbon fiber, or the like can be used. As the carbon fibers, for example, carbon fibers such as mesophase pitch-based carbon fibers and isotropic pitch-based carbon fibers can be used. Moreover, carbon nanofiber, a carbon nanotube, etc. can be used as carbon fiber. Carbon nanotubes can be produced by, for example, a vapor phase growth method. Further, as the conductive assistant, for example, a carbon material such as carbon black (acetylene black (AB) or the like) or graphene can be used. Further, for example, metal powder such as copper, nickel, aluminum, silver, gold, metal fiber, conductive ceramic material, or the like can be used.

Flaky graphene has excellent electrical properties such as high electrical conductivity, and excellent physical properties such as flexibility and mechanical strength. Therefore, by using graphene as a conductive additive, the contact point and the contact area between the active materials can be increased.

The active material layer 102 preferably includes a binder, and the binder preferably includes a water-soluble polymer. The active material layer 102 may include a plurality of types of binders.

As the binder, it is preferable to use rubber materials such as styrene-butadiene rubber (SBR), styrene / isoprene / styrene rubber, acrylonitrile / butadiene rubber, butadiene rubber, and ethylene / propylene / diene copolymer. These rubber materials are more preferably used in combination with water-soluble polymers. Since these rubber materials have rubber elasticity and are easy to expand and contract, they are resistant to the stress associated with expansion / contraction of the active material accompanying charging / discharging and bending of the electrode, and can provide a highly reliable electrode. In some cases, it has a hydrophobic group and is hardly soluble in water. In such a case, since the particles are dispersed in an aqueous solution without being dissolved in water, a composition containing a solvent used for forming the active material layer 102 (also referred to as an electrode mixture composition) is applied. It may be difficult to increase the viscosity to a suitable level. At this time, if a water-soluble polymer having a high viscosity adjusting function, such as a polysaccharide, is used, an effect of appropriately increasing the viscosity of the solution can be expected, and the rubber material and the rubber material are uniformly dispersed with each other. An electrode, for example, an electrode with high uniformity of electrode film thickness and electrode resistance can be obtained.

As binders, polystyrene, polymethyl acrylate, polymethyl methacrylate (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoro Materials such as ethylene, polyethylene, polypropylene, isobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), and polyacrylonitrile (PAN) may be used.

Each binder may be used alone, or two or more binders may be used in combination.

<Method for producing electrode>
Next, a method for manufacturing the electrode 100 which is one embodiment of the present invention is described.

First, an electrode mixture composition is prepared. The electrode mixture composition can be prepared, for example, by using the above-described active material, adding a binder, a conductive auxiliary agent, and the like and kneading with a solvent. The electrode mixture composition may be a slurry or a paste. In addition, as a solvent, water, NMP (N-methyl-2-pyrrolidone), etc. can be used, for example. From the viewpoint of safety and cost, it is preferable to use water.

As an example, the case where the electrode 100 is a positive electrode for a storage battery will be described. Here, an example in which the active material according to one embodiment of the present invention is used as an active material, acetylene black is used as a conductive additive, PVdF is used as a binder, and NMP is used as a solvent is described.

First, the active material according to one embodiment of the present invention, acetylene black, and polyvinylidene fluoride are mixed. An electrode mixture composition can be formed by adding NMP to these mixtures until a predetermined viscosity is obtained, and kneading. In this step, kneading and addition of the polar solvent may be repeated a plurality of times. The electrode mixture composition may be a slurry or a paste.

Through the above steps, an electrode mixture composition in which the active material, the conductive aid, and the binder are uniformly dispersed can be formed.

Here, an undercoat may be formed on the current collector. The undercoat refers to a coating layer for reducing contact resistance and improving adhesion between the current collector and the active material layer. As the undercoat, for example, a carbon layer, a metal layer, a layer including carbon and a polymer, and a layer including a layer including a metal and a polymer can be used. By forming the undercoat on the current collector, the contact resistance between the current collector formed later and the active material layer can be reduced. In addition, adhesion between the current collector and the active material layer can be improved. In the case where graphene is used as the conductive assistant, the undercoat is preferably not dissolved by the reducing solution in the graphene oxide reduction step.

Further, as the undercoat, for example, a dispersion aqueous solution such as graphite or acetylene black, or a mixture of the aqueous solution with a polymer can be used, for example, a mixture of graphite and sodium polyacrylate (PAANA), Further, a mixture of AB and PVdF can be used. Further, the blending ratio of graphite and PAA may be graphite: PAA = 95: 5 to 50:50, and the blending ratio of AB and PVdF may be AB: PVdF = 70: 30 to 50:50.

Note that the undercoat is not necessarily formed on the current collector as long as there is no problem with the adhesion between the active material layer and the current collector, electrode strength, and contact resistance.

Next, the slurry is provided on one side or both sides of the current collector by, for example, a coating method such as a doctor blade method.

Next, the active material layer is formed by drying the slurry provided on the current collector by a method such as ventilation drying or reduced pressure (vacuum) drying. This drying may be performed using, for example, hot air of 50 ° C. or higher and 180 ° C. or lower. By this step, the polar solvent contained in the active material layer is evaporated. The atmosphere is not particularly limited.

Here, the density of the active material layer may be increased by applying pressure to the active material layer by a compression method such as a roll press method or a flat plate press method. In addition, when pressing is performed, heat of 90 ° C. or higher and 180 ° C. or lower, preferably 120 ° C. or lower, is applied to the binder (for example, PVdF) contained in the undercoat or the active material layer so as not to change the electrode characteristics. By softening to the extent, the adhesion between the current collector and the active material layer can be further enhanced.

Next, the pressed active material layer is dried. Drying may be performed under reduced pressure (vacuum) or in a reducing atmosphere. This drying step may be performed, for example, at a temperature of 50 ° C. or higher and 300 ° C. or lower for 1 hour or longer and 48 hours or shorter. By this drying, the polar solvent and water present in the active material layer are well evaporated or removed.

Further, the current collector on which the active material layer is formed may be pressed. Thereby, the adhesiveness of an active material layer and a collector can be improved. In addition, the density of the active material layer can be increased. In addition, when pressing is performed, heat of 90 ° C. or higher and 180 ° C. or lower, preferably 120 ° C. or lower, is applied to the binder (for example, PVdF) contained in the undercoat or the active material layer so as not to change the electrode characteristics. By softening to the extent, the adhesion between the current collector and the active material layer can be further enhanced.

Finally, the current collector and the active material layer are punched into a predetermined size to produce an electrode.

By using the lithium manganese composite oxide according to one embodiment of the present invention as an active material, lithium ions can be easily diffused in the active material, and a decrease in battery voltage and a decrease in discharge capacity can be prevented. .

However, when the amount of metal atoms in the lithium manganese composite oxide becomes too large, excessive metal atoms enter the layered rock salt type crystal structure region, thereby inhibiting the diffusion, insertion and desorption of lithium ions. Therefore, in the lithium manganese composite oxide, the molar ratio of manganese to metal atoms is 0.2 to 1.3, preferably 0.2 to 0.5, and more preferably 0.2 to 0.5, with respect to 1 for manganese. What should be done.

As described above, by using the lithium manganese composite oxide having a stacking fault as an electrode, it is possible to suppress a decrease in battery voltage and a decrease in discharge capacity. Thereby, the cycling characteristics of the battery accompanying charging / discharging can be improved.

Note that one embodiment of the present invention is described in this embodiment. Alternatively, in another embodiment, one embodiment of the present invention will be described. Note that one embodiment of the present invention is not limited thereto. That is, in this embodiment and other embodiments, various aspects of the invention are described; therefore, one embodiment of the present invention is not limited to a particular aspect. For example, as an embodiment of the present invention, an example in which the present invention is applied to a lithium ion secondary battery has been described. However, one embodiment of the present invention is not limited thereto. In some cases or depending on the situation, one embodiment of the present invention includes various secondary batteries, lead storage batteries, lithium ion polymer secondary batteries, nickel / hydrogen storage batteries, nickel / cadmium storage batteries, nickel / iron storage batteries, nickel -You may apply to a zinc storage battery, a silver oxide / zinc storage battery, a solid battery, an air battery, a primary battery, a capacitor, or a lithium ion capacitor. Alternatively, for example, depending on circumstances or circumstances, one embodiment of the present invention may not be applied to a lithium ion secondary battery.

This embodiment can be implemented in appropriate combination with any of the other embodiments.

(Embodiment 3)
In this embodiment, an example of a battery cell including an electrode which is one embodiment of the present invention will be described.

Note that in this specification and the like, a battery cell refers to all elements and devices having a power storage function. For example, a storage battery such as a lithium ion secondary battery, a lithium ion capacitor, and an electric double layer capacitor are included.
<Thin storage battery>
FIG. 4 shows a thin storage battery as an example of a battery cell. FIG. 4 shows an example of a thin storage battery. If the thin storage battery is configured to have flexibility, if the thin storage battery is mounted on an electronic device having at least a part of the flexibility, the storage battery can be bent in accordance with the deformation of the electronic device.

FIG. 4 shows an external view of a thin storage battery 500. 5A and 5B show an A1-A2 cross section and a B1-B2 cross section indicated by a dashed line in FIG. A thin storage battery 500 includes a positive electrode 503 having a positive electrode current collector 501 and a positive electrode active material layer 502, a negative electrode 506 having a negative electrode current collector 504 and a negative electrode active material layer 505, a separator 507, an electrolyte solution 508, and an exterior. And a body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in the exterior body 509. The exterior body 509 is filled with the electrolytic solution 508.

The electrode which is one embodiment of the present invention is used for at least one of the positive electrode 503 and the negative electrode 506. Alternatively, the electrode which is one embodiment of the present invention may be used for both the positive electrode 503 and the negative electrode 506.

First, the structure of the positive electrode 503 will be described. As the positive electrode 503, an electrode according to one embodiment of the present invention is preferably used. Here, an example in which the electrode 100 described in Embodiment 2 is used for the positive electrode 503 is described.

The solvent of the electrolytic solution 508 is preferably an aprotic organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl. Carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether , Methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in any combination and ratio.

Further, by using a polymer material that is gelled as a solvent for the electrolytic solution, the safety against liquid leakage and the like is increased. Further, the secondary battery can be made thinner and lighter. Typical examples of the polymer material to be gelated include silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide, polypropylene oxide, and fluorine-based polymer.

In addition, by using one or more ionic liquids (room temperature molten salts) that are flame retardant and volatile as the electrolyte solvent, the internal temperature rises due to internal short circuit or overcharge of the battery cell. In addition, the battery cell can be prevented from rupture or ignition. An ionic liquid consists of a cation and an anion, and contains an organic cation and an anion. Examples of organic cations used in the electrolyte include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, and aromatic cations such as imidazolium cations and pyridinium cations. In addition, as an anion used in the electrolytic solution, a monovalent amide anion, a monovalent methide anion, a fluorosulfonate anion, a perfluoroalkylsulfonate anion, a tetrafluoroborate, a perfluoroalkylborate, a hexafluorophosphate, or a perfluorophosphate anion. Examples thereof include fluoroalkyl phosphate.

As the electrolytes dissolved in the above solvent, when using a lithium carrier ion, e.g. _{LiPF 6, LiClO 4, LiAsF 6} , LiBF 4, LiAlCl 4, LiSCN, LiBr, LiI, Li 2 SO 4, Li 2 B ₁₀ Cl ₁₀ , Li ₂ B ₁₂ Cl ₁₂ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) ₂ , lithium salt such as LiN (C ₄ F ₉ SO ₂ ) (CF ₃ SO ₂ ), LiN (C ₂ F ₅ SO ₂ ) ₂ , or two or more of these in any combination and ratio Can be used.

In addition, as the electrolytic solution used for the battery cell, it is preferable to use a highly purified electrolytic solution having a small content of elements other than the constituent elements of the granular dust and the electrolytic solution (hereinafter also simply referred to as “impurities”). . Specifically, the weight ratio of impurities to the electrolytic solution is preferably 1% or less, preferably 0.1% or less, and more preferably 0.01% or less.

Further, additives such as vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), LiBOB may be added to the electrolytic solution. The concentration of the additive may be, for example, 0.1 weight% or more and 5 weight% or less with respect to the entire solvent.

Alternatively, a gel electrolyte obtained by swelling a polymer with an electrolytic solution may be used. Examples of the gel electrolyte (polymer gel electrolyte) include those using a host polymer as a carrier and containing the above-described electrolytic solution.

Examples of host polymers are described below. As the host polymer, for example, a polymer having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVdF, polyacrylonitrile, and a copolymer containing them can be used. For example, PVdF-HFP which is a copolymer of PVdF and hexafluoropropylene (HFP) can be used. Further, the formed polymer may have a porous shape.

In place of the electrolytic solution, a solid electrolyte having an inorganic material such as sulfide or oxide, or a solid electrolyte having a polymer material such as PEO (polyethylene oxide) can be used. When a solid electrolyte is used, it is not necessary to install a separator or a spacer. Further, since the entire battery can be solidified, there is no risk of leakage and the safety is greatly improved.

As the separator 507, for example, paper, non-woven fabric, glass fiber, ceramics, nylon (polyamide), vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyolefin, synthetic fiber using polyurethane, or the like is used. be able to.

The separator 507 is preferably processed into a bag shape and disposed so as to enclose either the positive electrode 503 or the negative electrode 506. For example, as illustrated in FIG. 6A, the separator 507 is folded in half so as to sandwich the positive electrode 503 and sealed by a sealing portion 514 outside the region overlapping the positive electrode 503, whereby the positive electrode 503 is separated from the separator 507. It can be reliably carried inside. Then, as shown in FIG. 6B, the thin storage battery 500 may be formed by alternately stacking the positive electrodes 503 and the negative electrodes 506 wrapped in the separator 507 and arranging them in the exterior body 509.

Next, aging after producing the storage battery will be described. It is preferable to perform aging after producing a storage battery. An example of the aging condition will be described below. First, charging is performed at a rate of 0.001C to 0.2C. The temperature may be, for example, room temperature or higher and 50 ° C. or lower. At this time, when the electrolytic solution is decomposed and gas is generated, if the gas accumulates in the cell, a region where the electrolytic solution cannot contact the electrode surface is generated. That is, this corresponds to a reduction in the effective reaction area of the electrode and an increase in the effective current density.

When the current density becomes excessively high, a voltage drop occurs according to the resistance of the electrode, lithium insertion into the graphite occurs, and at the same time, lithium deposition on the graphite surface also occurs. This lithium deposition may cause a decrease in capacity. For example, if a film or the like grows on the surface after lithium is deposited, lithium that is deposited on the surface cannot be re-eluted and lithium that does not contribute to the capacity is generated. Further, when the deposited lithium physically collapses and loses conduction with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent the gas before the electrode reaches the lithium potential due to a voltage drop.

Further, after degassing, it may be held at a temperature higher than room temperature, preferably 30 ° C. or more and 60 ° C. or less, more preferably 35 ° C. or more and 50 ° C. or less, for example, for 1 hour or more and 100 hours or less. Good. During the initial charging, the electrolytic solution decomposed on the surface forms a film on the surface of the graphite. Therefore, for example, a case where the formed film is densified by holding at a temperature higher than room temperature after degassing may be considered.

FIG. 7B shows an example in which a current collector is welded to a lead electrode. As an example, an example in which the positive electrode current collector 501 is welded to the positive electrode lead electrode 510 is shown. The positive electrode current collector 501 is welded to the positive electrode lead electrode 510 in the welding region 512 using ultrasonic welding or the like. In addition, since the positive electrode current collector 501 includes the curved portion 513 illustrated in FIG. 7B, stress generated by external force applied after the storage battery 500 is manufactured can be relieved, and the reliability of the storage battery 500 can be reduced. Can be increased.

In the thin storage battery 500 shown in FIGS. 4 and 5, the positive electrode lead electrode 510 and the negative electrode lead 511 are ultrasonically bonded to the positive electrode current collector 501 or the negative electrode current collector 504 using the positive electrode lead electrode 510 and the negative electrode lead electrode 511. The electrode 511 is exposed to the outside. In addition, the positive electrode current collector 501 and the negative electrode current collector 504 can also serve as terminals for obtaining electrical contact with the outside. In that case, a part of the positive electrode current collector 501 and the negative electrode current collector 504 may be disposed so as to be exposed to the outside from the exterior body 509 without using the lead electrode.

In FIG. 4, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are arranged on the same side, but as shown in FIG. 8, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 may be arranged on different sides. Thus, the storage battery of one embodiment of the present invention has a high degree of design freedom because the lead electrode can be freely arranged. Therefore, the design freedom of a product using the storage battery of one embodiment of the present invention can be increased. In addition, productivity of a product using the storage battery of one embodiment of the present invention can be increased.

In the thin storage battery 500, a metal thin film having excellent flexibility such as aluminum, stainless steel, copper, or nickel is formed on the exterior body 509 on a film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, or polyamide. Further, a film having a three-layer structure in which an insulating synthetic resin film such as a polyamide resin or a polyester resin is provided on the metal thin film as the outer surface of the outer package can be used.

In FIG. 4, as an example, the number of pairs of positive and negative electrodes facing each other is five, but of course, the number of pairs of electrodes is not limited to five, and may be large or small. When there are many electrode layers, it can be set as the storage battery which has more capacity | capacitance. Moreover, when there are few electrode layers, it can be made thin and can be set as the storage battery excellent in flexibility.

In the above structure, the exterior body 509 of the secondary battery can be deformed within a range of a curvature radius of 10 mm or more, preferably a curvature radius of 30 mm or more. The film that is the outer package of the secondary battery is composed of one or two sheets. When the film is a secondary battery having a laminated structure, the cross-sectional structure of the curved battery is two curves of the film that is the outer package. The structure is sandwiched between.

Here, the radius of curvature of the surface will be described with reference to FIG. In FIG. 9A, in a plane 1701 obtained by cutting the curved surface 1700, a part of the curve 1702 included in the curved surface 1700 is approximated to a circular arc, the radius of the circle is a curvature radius 1703, and the center of the circle is the curvature. The center is 1704. FIG. 9B shows a top view of the curved surface 1700. FIG. 9C is a cross-sectional view in which a curved surface 1700 is cut along a plane 1701. When cutting a curved surface with a plane, the radius of curvature of the curve appearing in the cross section varies depending on the angle of the plane with respect to the curved surface and the cutting position. In this specification, the smallest radius of curvature is the radius of curvature of the surface. And

When the secondary battery sandwiching the electrode / electrolytic solution 1805 with the two films as the outer package is curved, the curvature radius 1802 of the film 1801 on the side close to the curvature center 1800 of the secondary battery is from the curvature center 1800. The radius of curvature 1804 of the far film 1803 is smaller (FIG. 10A). When the secondary battery is curved to have a circular arc cross section, a compressive stress is applied to the surface of the film close to the center of curvature 1800, and a tensile stress is applied to the surface of the film far from the center of curvature 1800 (FIG. 10B). If a pattern formed by a concave portion or a convex portion is formed on the surface of the exterior body, even if a compressive stress or a tensile stress is applied as described above, the influence of the strain can be suppressed within an allowable range. Therefore, the secondary battery can be deformed in such a range that the curvature radius of the exterior body on the side close to the center of curvature is 10 mm or more, preferably 30 mm or more.

Note that the cross-sectional shape of the secondary battery is not limited to a simple arc shape, and a part of the secondary battery can have an arc shape. For example, the shape shown in FIG. ), S-shape or the like. When the curved surface of the secondary battery has a shape having a plurality of centers of curvature, the curved surface having the smallest curvature radius among the curvature radii at each of the plurality of centers of curvature is the one closer to the center of curvature of the two exterior bodies. The secondary battery can be deformed in a range where the curvature radius of the outer package is 10 mm or more, preferably 30 mm or more.

<Coin-type storage battery>
Next, as an example of a battery cell, an example of a coin-type storage battery will be described with reference to FIG. FIG. 11A is an external view of a coin-type (single-layer flat type) storage battery, and FIG. 11B is a cross-sectional view thereof.

In the coin-type storage battery 300, a positive electrode can 301 also serving as a positive electrode terminal and a negative electrode can 302 also serving as a negative electrode terminal are insulated and sealed with a gasket 303 formed of polypropylene or the like. The positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided so as to be in contact therewith. For the positive electrode active material layer 306, the description of the positive electrode active material layer 502 may be referred to.

The negative electrode 307 is formed of a negative electrode current collector 308 and a negative electrode active material layer 309 provided so as to be in contact therewith. For the negative electrode active material layer 309, the description of the negative electrode active material layer 505 may be referred to. For the separator 310, the description of the separator 507 may be referred to. For the electrolytic solution, the description of the electrolytic solution 508 may be referred to.

Note that each of the positive electrode 304 and the negative electrode 307 used in the coin-type storage battery 300 may have an active material layer formed only on one side.

The positive electrode can 301 and the negative electrode can 302 are made of a metal such as nickel, aluminum, titanium, or the like, or an alloy of these and other metals (for example, stainless steel) that has corrosion resistance to the electrolytic solution. Can be used. In order to prevent corrosion due to the electrolytic solution, it is preferable to coat nickel, aluminum, or the like. The positive electrode can 301 and the negative electrode can 302 are electrically connected to the positive electrode 304 and the negative electrode 307, respectively.

The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated in the electrolyte, and the positive electrode 304, the separator 310, the negative electrode 307, and the negative electrode can 302 are laminated in this order with the positive electrode can 301 facing down, as shown in FIG. Then, the positive electrode can 301 and the negative electrode can 302 are pressure-bonded via a gasket 303 to manufacture a coin-shaped storage battery 300.

<Cylindrical storage battery>
Next, a cylindrical storage battery is shown as an example of a battery cell. A cylindrical storage battery will be described with reference to FIG. As shown in FIG. 12A, the cylindrical storage battery 600 has a positive electrode cap (battery cover) 601 on the top surface and a battery can (outer can) 602 on the side surface and bottom surface. The positive electrode cap and the battery can (outer can) 602 are insulated by a gasket (insulating packing) 610.

FIG. 12B is a diagram schematically showing a cross section of a cylindrical storage battery. Inside the hollow cylindrical battery can 602, a battery element in which a strip-like positive electrode 604 and a negative electrode 606 are wound with a separator 605 interposed therebetween is provided. Although not shown, the battery element is wound around a center pin. The battery can 602 has one end closed and the other end open. For the battery can 602, a metal such as nickel, aluminum, titanium, or the like having corrosion resistance to the electrolytic solution, or an alloy thereof or an alloy of these with another metal (for example, stainless steel) can be used. . In order to prevent corrosion due to the electrolytic solution, it is preferable to coat nickel, aluminum, or the like. Inside the battery can 602, the battery element in which the positive electrode, the negative electrode, and the separator are wound is sandwiched between a pair of opposing insulating plates 608 and 609. Further, a non-aqueous electrolyte (not shown) is injected into the inside of the battery can 602 provided with the battery element. As the non-aqueous electrolyte, the same one as a coin-type storage battery can be used.

What is necessary is just to manufacture the positive electrode 604 and the negative electrode 606 similarly to the positive electrode and negative electrode of a thin storage battery which were mentioned above. In addition, since the positive electrode and the negative electrode used for the cylindrical storage battery are wound, it is preferable to form an active material on both surfaces of the current collector. A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collecting lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can use a metal material such as aluminum. The positive terminal 603 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the increase in the internal pressure of the battery exceeds a predetermined threshold value. The PTC element 611 is a heat-sensitive resistance element that increases in resistance when the temperature rises, and prevents abnormal heat generation by limiting the amount of current by increasing the resistance. For the PTC element, barium titanate (BaTiO ₃ ) -based semiconductor ceramics or the like can be used.

In the present embodiment, coin-type, cylindrical-type, and thin-type storage batteries are shown as the storage battery, but various types of storage batteries such as other sealed storage batteries and rectangular storage batteries can be used. Alternatively, a structure in which a plurality of positive electrodes, negative electrodes, and separators are stacked, or a structure in which positive electrodes, negative electrodes, and separators are wound may be employed. For example, examples of other storage batteries are shown in FIGS.

<Example configuration of storage battery>
13 and 14 show a configuration example of a thin storage battery. A wound body 993 illustrated in FIG. 13A includes a negative electrode 994, a positive electrode 995, and a separator 996.

The wound body 993 is obtained by winding the negative electrode 994 and the positive electrode 995 so as to overlap each other with the separator 996 interposed therebetween, and winding the laminated sheet. A rectangular secondary battery is manufactured by covering the wound body 993 with a rectangular sealing container or the like.

Note that the number of stacked layers including the negative electrode 994, the positive electrode 995, and the separator 996 may be appropriately designed according to the required capacity and element volume. The negative electrode 994 is connected to a negative electrode current collector (not shown) via one of a lead electrode 997 and a lead electrode 998, and the positive electrode 995 is connected to the positive electrode current collector (not shown) via the other of the lead electrode 997 and the lead electrode 998. Connected).

A storage battery 990 illustrated in FIGS. 13B and 13C includes a wound body 993 described above in a space formed by bonding a film 981 serving as an exterior body and a film 982 having a concave portion by thermocompression bonding or the like. Is stored. The wound body 993 includes a lead electrode 997 and a lead electrode 998, and is impregnated with an electrolytic solution inside the film 981 and the film 982 having a recess.

For the film 981 and the film 982 having a recess, for example, a metal material such as aluminum or a resin material can be used. If a resin material is used as the material of the film 981 and the film 982 having a recess, the film 981 and the film 982 having a recess can be deformed when an external force is applied, and a flexible storage battery is manufactured. be able to.

13B and 13C show an example in which two films are used, a space is formed by bending one film, and the winding body 993 described above is formed in the space. It may be stored.

Moreover, not only a thin storage battery but a flexible battery cell can be produced by using a resin material or the like for an exterior body or a sealing container. However, when the exterior body or the sealing container is made of a resin material, the portion to be connected to the outside is made of a conductive material.

For example, an example of another thin storage battery having flexibility is shown in FIG. Since the wound body 993 in FIG. 14A is the same as that shown in FIG. 13A, detailed description thereof will be omitted.

A storage battery 990 shown in FIGS. 14B and 14C has the above-described wound body 993 housed inside an exterior body 991. The wound body 993 has a lead electrode 997 and a lead electrode 998, and is impregnated with an electrolytic solution inside the exterior bodies 991, 992. For the exterior bodies 991, 992, for example, a metal material such as aluminum or a resin material can be used. When a resin material is used as the material of the exterior bodies 991 and 992, the exterior bodies 991 and 992 can be deformed when an external force is applied, and a flexible thin storage battery can be manufactured.

By using the lithium manganese composite oxide according to one embodiment of the present invention as an active material, lithium ions can be easily diffused in the active material, and a decrease in battery voltage and a decrease in discharge capacity can be prevented. .

However, when the amount of metal atoms in the lithium manganese composite oxide becomes too large, excessive metal atoms enter the layered rock salt type crystal structure region, thereby inhibiting the diffusion, insertion and desorption of lithium ions. Therefore, in the lithium manganese composite oxide, the molar ratio of manganese to metal atoms is 0.2 to 1.3, preferably 0.2 to 0.5, and more preferably 0.2 to 0.5, with respect to 1 for manganese. What should be done.

As described above, by using the lithium manganese composite oxide having a stacking fault as an electrode, it is possible to suppress a decrease in battery voltage and a decrease in discharge capacity. Thereby, the cycling characteristics of the battery accompanying charging / discharging can be improved.

<Example structure of power storage system>
In addition, structural examples of the power storage system will be described with reference to FIGS. Here, the power storage system refers to, for example, a device equipped with a battery cell.

FIG. 15A and FIG. 15B are external views of a power storage system. The power storage system includes a circuit board 900 and a storage battery 913. A label 910 is attached to the storage battery 913. Further, as illustrated in FIG. 15B, the power storage system includes a terminal 951 and a terminal 952, and an antenna 914 and an antenna 915 on the back of the label 910.

The circuit board 900 includes a terminal 911 and a circuit 912. The terminal 911 is connected to the terminal 951, the terminal 952, the antenna 914, the antenna 915, and the circuit 912. Note that a plurality of terminals 911 may be provided, and each of the plurality of terminals 911 may be a control signal input terminal, a power supply terminal, or the like.

The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 914 and the antenna 915 are not limited to a coil shape, and may be a linear shape or a plate shape, for example. An antenna such as a planar antenna, an aperture antenna, a traveling wave antenna, an EH antenna, a magnetic field antenna, or a dielectric antenna may be used. Alternatively, the antenna 914 or the antenna 915 may be a flat conductor. The flat conductor can function as one of electric field coupling conductors. That is, the antenna 914 or the antenna 915 may function as one of the two conductors of the capacitor. Thereby, not only an electromagnetic field and a magnetic field but power can also be exchanged by an electric field.

The line width of the antenna 914 is preferably larger than the line width of the antenna 915. Accordingly, the amount of power received by the antenna 914 can be increased.

The power storage system includes a layer 916 between the antenna 914 and the antenna 915 and the storage battery 913. The layer 916 has a function of shielding an electromagnetic field generated by the storage battery 913, for example. As the layer 916, for example, a magnetic material can be used.

Note that the structure of the power storage system is not limited to the structure illustrated in FIG.

For example, as shown in FIGS. 16A-1 and 16A-2, an antenna is provided on each of a pair of opposed surfaces of the storage battery 913 shown in FIGS. 15A and 15B. It may be provided. FIG. 16A-1 is an external view seen from one side direction of the pair of surfaces, and FIG. 16A-2 is an external view seen from the other side direction of the pair of surfaces. Note that for the same portion as the power storage system illustrated in FIGS. 15A and 15B, the description of the power storage system illustrated in FIGS. 15A and 15B can be incorporated as appropriate.

As shown in FIG. 16A-1, an antenna 914 is provided on one of a pair of surfaces of the storage battery 913 with a layer 916 sandwiched therebetween, and as shown in FIG. 16A-2, a pair of surfaces of the storage battery 913 is provided. An antenna 915 is provided with the layer 917 interposed therebetween. The layer 917 has a function of shielding an electromagnetic field generated by the storage battery 913, for example. As the layer 917, for example, a magnetic material can be used.

With the above structure, the size of both the antenna 914 and the antenna 915 can be increased.

Alternatively, as illustrated in FIGS. 16B-1 and 16B-2, each of the pair of opposed surfaces of the storage battery 913 illustrated in FIGS. 15A and 15B is different. An antenna may be provided. 16B-1 is an external view seen from one side direction of the pair of surfaces, and FIG. 16B-2 is an external view seen from the other side direction of the pair of surfaces. Note that for the same portion as the power storage system illustrated in FIGS. 15A and 15B, the description of the power storage system illustrated in FIGS. 15A and 15B can be incorporated as appropriate.

As shown in FIG. 16B-1, an antenna 914 and an antenna 915 are provided on one of a pair of surfaces of the storage battery 913 with the layer 916 interposed therebetween, and as shown in FIG. An antenna 918 is provided with the layer 917 interposed between the other of the pair of surfaces. The antenna 918 has a function of performing data communication with an external device, for example. For the antenna 918, for example, an antenna having a shape applicable to the antenna 914 and the antenna 915 can be used. As a communication method between the power storage system and the other devices via the antenna 918, a response method that can be used between the power storage system and the other devices such as NFC can be applied.

Alternatively, as illustrated in FIG. 17A, a display device 920 may be provided in the storage battery 913 illustrated in FIGS. 15A and 15B. The display device 920 is electrically connected to the terminal 911 through the terminal 919. Note that the label 910 is not necessarily provided in a portion where the display device 920 is provided. Note that for the same portion as the power storage system illustrated in FIGS. 15A and 15B, the description of the power storage system illustrated in FIGS. 15A and 15B can be incorporated as appropriate.

The display device 920 may display, for example, an image indicating whether charging is being performed, an image indicating the amount of stored power, or the like. As the display device 920, for example, electronic paper, a liquid crystal display device, an electroluminescence (also referred to as EL) display device, or the like can be used. For example, power consumption of the display device 920 can be reduced by using electronic paper.

Alternatively, as illustrated in FIG. 17B, a sensor 921 may be provided in the storage battery 913 illustrated in FIGS. 15A and 15B. The sensor 921 is electrically connected to the terminal 911 through the terminal 922. Note that the sensor 921 may be provided on the back side of the label 910. Note that for the same portion as the power storage system illustrated in FIGS. 15A and 15B, the description of the power storage system illustrated in FIGS. 15A and 15B can be incorporated as appropriate.

Examples of the sensor 921 include force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, and radiation. Those having a function of measuring flow rate, humidity, gradient, vibration, odor or infrared ray can be used. By providing the sensor 921, for example, data (temperature or the like) indicating an environment where the power storage system is placed can be detected and stored in a memory in the circuit 912.

An electrode according to one embodiment of the present invention is used for the storage battery or the power storage system described in this embodiment. Therefore, the capacity of the storage battery or the power storage system can be increased. In addition, the energy density can be increased. Moreover, reliability can be improved. In addition, the lifetime can be extended.

This embodiment can be implemented in appropriate combination with any of the other embodiments.

(Embodiment 4)
FIG. 18 to FIG. 18 illustrate a battery control unit (BMU) that can be used in combination with the battery cell including the active material described in the above embodiment and a transistor suitable for a circuit included in the battery control unit. Explanation will be made with reference to FIG. In this embodiment, a battery control unit of a power storage device having battery cells connected in series will be described.

When charging / discharging is repeated for a plurality of battery cells connected in series, the capacity (output voltage) varies depending on variations in characteristics between the battery cells. In battery cells connected in series, the capacity at the time of overall discharge depends on the battery cells having a small capacity. If the capacity varies, the capacity at the time of discharge decreases. In addition, if charging is performed with reference to a battery cell having a small capacity, there is a risk of insufficient charging. Moreover, if charging is performed with reference to a battery cell having a large capacity, there is a risk of overcharging.

Therefore, the battery control unit of the power storage device having the battery cells connected in series has a function of aligning the variation in capacity between the battery cells that causes insufficient charging or overcharging. The circuit configuration for aligning the variation in capacity between battery cells includes a resistance method, a capacitor method, or an inductor method, but here is an example of a circuit configuration that can use a transistor with a small off-current to equalize the variation in capacity. Will be described.

As the transistor with low off-state current, a transistor including an oxide semiconductor (OS transistor) in a channel formation region is preferable. By using an OS transistor with a small off-state current in the circuit configuration of the battery control unit of the power storage device, the amount of charge leaking from the battery can be reduced, and a decrease in capacity over time can be suppressed.

As the oxide semiconductor used for the channel formation region, an In-M-Zn oxide (M is Ga, Sn, Y, Zr, La, Ce, or Nd) is used. In the target used for forming the oxide semiconductor film, when the atomic ratio of metal elements is In: M: Zn = x ₁ : y ₁ : z _{1 ,} x ₁ / y ₁ is 1/3 or more 6 Hereinafter, it is further 1 or more and 6 or less, and z ₁ / y ₁ is preferably 1/3 or more and 6 or less, and more preferably 1 or more and 6 or less. Note that when z ₁ / y ₁ is greater than or equal to 1 and less than or equal to 6, a CAAC-OS film can be easily formed as the oxide semiconductor film.

Here, the CAAC-OS film is described.

The CAAC-OS film is one of oxide semiconductor films having a plurality of c-axis aligned crystal parts.

Confirming a plurality of crystal parts by observing a bright field image of a CAAC-OS film and a combined analysis image (also referred to as a high-resolution TEM image) of a CAAC-OS film with a transmission electron microscope (TEM: Transmission Electron Microscope). Can do. On the other hand, a clear boundary between crystal parts, that is, a crystal grain boundary (also referred to as a grain boundary) cannot be confirmed even by a high-resolution TEM image. Therefore, it can be said that the CAAC-OS film is unlikely to decrease in electron mobility due to crystal grain boundaries.

When a high-resolution TEM image of a cross section of the CAAC-OS film is observed from a direction substantially parallel to the sample surface, it can be confirmed that metal atoms are arranged in layers in the crystal part. Each layer of metal atoms has a shape reflecting unevenness of a surface (also referred to as a formation surface) or an upper surface on which the CAAC-OS film is formed, and is arranged in parallel with the formation surface or the upper surface of the CAAC-OS film. .

On the other hand, when a high-resolution TEM image of a plane of the CAAC-OS film is observed from a direction substantially perpendicular to the sample surface, it can be confirmed that metal atoms are arranged in a triangular shape or a hexagonal shape in a crystal part. However, there is no regularity in the arrangement of metal atoms between different crystal parts.

When structural analysis is performed on a CAAC-OS film using an X-ray diffraction (XRD) apparatus, for example, in the analysis of a CAAC-OS film having an InGaZnO ₄ crystal by an out-of-plane method, A peak may appear when the diffraction angle (2θ) is around 31 °. Since this peak is attributed to the (009) plane of the InGaZnO ₄ crystal, the crystal of the CAAC-OS film has c-axis orientation, and the c-axis is oriented in a direction substantially perpendicular to the formation surface or the top surface. Can be confirmed.

Note that when the CAAC-OS film including an InGaZnO ₄ crystal is analyzed by an out-of-plane method, a peak may also appear when 2θ is around 36 ° in addition to the peak where 2θ is around 31 °. A peak at 2θ of around 36 ° indicates that a crystal having no c-axis alignment is included in part of the CAAC-OS film. The CAAC-OS film preferably has a peak at 2θ of around 31 ° and no peak at 2θ of around 36 °.

The CAAC-OS film is an oxide semiconductor film with a low impurity concentration. The impurity is an element other than the main component of the oxide semiconductor film, such as hydrogen, carbon, silicon, or a transition metal element. In particular, an element such as silicon, which has a stronger bonding force with oxygen than the metal element included in the oxide semiconductor film, disturbs the atomic arrangement of the oxide semiconductor film by depriving the oxide semiconductor film of oxygen, and has crystallinity. It becomes a factor to reduce. In addition, heavy metals such as iron and nickel, argon, carbon dioxide, and the like have large atomic radii (or molecular radii). Therefore, if they are contained inside an oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disturbed, resulting in crystallinity. It becomes a factor to reduce. Note that the impurity contained in the oxide semiconductor film might serve as a carrier trap or a carrier generation source.

The CAAC-OS film is an oxide semiconductor film with a low density of defect states. For example, oxygen vacancies in the oxide semiconductor film can serve as carrier traps or can generate carriers by capturing hydrogen.

A low impurity concentration and a low density of defect states (small number of oxygen vacancies) is called high purity intrinsic or substantially high purity intrinsic. A highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has few carrier generation sources, and thus can have a low carrier density. Therefore, a transistor including the oxide semiconductor film is unlikely to have electrical characteristics (also referred to as normally-on) in which the threshold voltage is negative. A highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has few carrier traps. Therefore, a transistor including the oxide semiconductor film has a small change in electrical characteristics and has high reliability. Note that the charge trapped in the carrier trap of the oxide semiconductor film takes a long time to be released, and may behave as if it were a fixed charge. Therefore, a transistor including an oxide semiconductor film with a high impurity concentration and a high density of defect states may have unstable electrical characteristics.

In addition, a transistor including a CAAC-OS film has little variation in electrical characteristics due to irradiation with visible light or ultraviolet light.

Note that an OS transistor has a larger band gap than a transistor having silicon in a channel formation region (Si transistor), and thus dielectric breakdown is less likely to occur when a high voltage is applied. When battery cells are connected in series, a voltage of several hundred volts is generated. However, the circuit configuration of the battery control unit of the power storage device applied to such a battery cell may be configured by the OS transistor described above. Is suitable.

FIG. 18 illustrates an example of a block diagram of a power storage device. A power storage device 6000 illustrated in FIG. 18 is connected in series with a terminal pair 6001, a terminal pair 6002, a switching control circuit 6003, a switching circuit 6004, a switching circuit 6005, a transformation control circuit 6006, and a transformation circuit 6007. A battery portion 6008 including a plurality of battery cells 6009.

18 includes a terminal pair 6001, a terminal pair 6002, a switching control circuit 6003, a switching circuit 6004, a switching circuit 6005, a transformation control circuit 6006, and a transformation circuit 6007. The part can be called a battery control unit.

A switching control circuit 6003 controls operations of the switching circuit 6004 and the switching circuit 6005. Specifically, the switching control circuit 6003 determines a battery cell (discharge battery cell group) to be discharged and a battery cell (charge battery cell group) to be charged based on the voltage measured for each battery cell 6009.

Further, the switching control circuit 6003 outputs a control signal S1 and a control signal S2 based on the determined discharge battery cell group and charge battery cell group. The control signal S1 is output to the switching circuit 6004. This control signal S1 is a signal for controlling the switching circuit 6004 so as to connect the terminal pair 6001 and the discharge battery cell group. The control signal S2 is output to the switching circuit 6005. This control signal S2 is a signal for controlling the switching circuit 6005 so as to connect the terminal pair 6002 and the rechargeable battery cell group.

In addition, the switching control circuit 6003 is based on the configuration of the switching circuit 6004, the switching circuit 6005, and the transformer circuit 6007 so that terminals of the same polarity are connected between the terminal pair 6002 and the rechargeable battery cell group. A control signal S1 and a control signal S2 are generated.

Details of the operation of the switching control circuit 6003 will be described.

First, the switching control circuit 6003 measures the voltage for each of the plurality of battery cells 6009. Then, the switching control circuit 6003, for example, uses a battery cell 6009 having a voltage equal to or higher than a predetermined threshold as a high voltage battery cell (high voltage cell) and a battery cell 6009 having a voltage lower than the predetermined threshold as a low voltage battery cell (constant Voltage cell).

Various methods can be used for determining the high voltage cell and the low voltage cell. For example, the switching control circuit 6003 determines whether each battery cell 6009 is a high voltage cell or a low voltage cell with reference to the voltage of the battery cell 6009 having the highest voltage or the lowest voltage among the plurality of battery cells 6009. You may judge. In this case, the switching control circuit 6003 determines whether each battery cell 6009 is a high voltage cell or a low voltage cell by determining whether the voltage of each battery cell 6009 is equal to or higher than a predetermined ratio with respect to the reference voltage. Can be judged. Then, the switching control circuit 6003 determines the discharge battery cell group and the charge battery cell group based on the determination result.

In the plurality of battery cells 6009, a high voltage cell and a low voltage cell can be mixed in various states. For example, in the switching control circuit 6003, among the high-voltage cells and the low-voltage cells, the portion where the highest number of high-voltage cells are connected in series is the discharge battery cell group. In addition, the switching control circuit 6003 sets a portion where the most low voltage cells are continuously connected in series as a rechargeable battery cell group. In addition, the switching control circuit 6003 may preferentially select the battery cell 6009 that is close to overcharge or overdischarge as the discharge battery cell group or the charge battery cell group.

Here, an operation example of the switching control circuit 6003 in this embodiment will be described with reference to FIG. FIG. 19 is a diagram for explaining an operation example of the switching control circuit 6003. For convenience of explanation, FIG. 19 illustrates an example in which four battery cells 6009 are connected in series.

First, in the example of FIG. 19A, when the voltages of the battery cells a to d are the voltages Va to Vd, a case where Va = Vb = Vc> Vd is shown. That is, three continuous high voltage cells a to c and one low voltage cell d are connected in series. In this case, the switching control circuit 6003 determines three consecutive high voltage cells a to c as a discharge battery cell group. In addition, the switching control circuit 6003 determines the low voltage cell D as a rechargeable battery cell group.

Next, the example of FIG. 19B shows a case where Vc >> Va = Vb >> Vd. That is, two continuous low voltage cells a and b, one high voltage cell c, and one low voltage cell d near overdischarge are connected in series. In this case, the switching control circuit 6003 determines the high voltage cell c as a discharge battery cell group. In addition, the switching control circuit 6003 preferentially determines the low voltage cell d as the rechargeable battery cell group instead of the two continuous low voltage cells a and b because the low voltage cell d is close to overdischarge.

Finally, the example of FIG. 19C shows a case where Va> Vb = Vc = Vd. That is, one high voltage cell a and three consecutive low voltage cells b to d are connected in series. In this case, the switching control circuit 6003 determines the high voltage cell a as a discharge battery cell group. In addition, the switching control circuit 6003 determines three consecutive low voltage cells b to d as a rechargeable battery cell group.

The switching control circuit 6003 is a control signal in which information indicating the discharge battery cell group to which the switching circuit 6004 is connected is set based on the results determined as in the example of FIGS. 19A to 19C. The control signal S2 in which information indicating S1 and the rechargeable battery cell group to which the switching circuit 6005 is connected is set is output to the switching circuit 6004 and the switching circuit 6005, respectively.

The above is the description regarding the details of the operation of the switching control circuit 6003.

The switching circuit 6004 sets the connection destination of the terminal pair 6001 to the discharge battery cell group determined by the switching control circuit 6003 in accordance with the control signal S1 output from the switching control circuit 6003.

The terminal pair 6001 includes a pair of terminals A1 and A2. The switching circuit 6004 connects one of the terminals A1 and A2 to the positive terminal of the battery cell 6009 located on the most upstream side (high potential side) in the discharge battery cell group, and the other to the discharge battery cell group. The connection destination of the terminal pair 6001 is set by connecting to the negative terminal of the battery cell 6009 located on the most downstream side (low potential side). Note that the switching circuit 6004 can recognize the position of the discharge battery cell group using information set in the control signal S1.

The switching circuit 6005 sets the connection destination of the terminal pair 6002 to the rechargeable battery cell group determined by the switching control circuit 6003 in accordance with the control signal S2 output from the switching control circuit 6003.

The terminal pair 6002 is configured by a pair of terminals B1 and B2. The switching circuit 6005 connects one of the terminals B1 and B2 to the positive terminal of the battery cell 6009 located on the most upstream side (high potential side) in the charging battery cell group, and the other is the charging battery cell group. The connection destination of the terminal pair 6002 is set by connecting to the negative electrode terminal of the battery cell 6009 located on the most downstream side (low potential side). Note that the switching circuit 6005 can recognize the position of the rechargeable battery cell group using the information set in the control signal S2.

20 and 21 are circuit diagrams illustrating configuration examples of the switching circuit 6004 and the switching circuit 6005. FIG.

In FIG. 20, the switching circuit 6004 includes a plurality of transistors 6010 and buses 6011 and 6012. The bus 6011 is connected to the terminal A1. The bus 6012 is connected to the terminal A2. One of the sources or drains of the plurality of transistors 6010 is alternately connected to the buses 6011 and 6012 every other pair. The other of the sources or drains of the plurality of transistors 6010 is connected between two adjacent battery cells 6009.

Note that, among the plurality of transistors 6010, the other of the source and the drain of the transistor 6010 located at the most upstream is connected to the positive terminal of the battery cell 6009 located at the most upstream of the battery portion 6008. In addition, among the plurality of transistors 6010, the other of the source and the drain of the transistor 6010 located on the most downstream side is connected to the negative electrode terminal of the battery cell 6009 located on the most downstream side of the battery portion 6008.

The switching circuit 6004 receives one of the plurality of transistors 6010 connected to the bus 6011 and one of the plurality of transistors 6010 connected to the bus 6012 in response to the control signal S1 applied to the gates of the plurality of transistors 6010. The discharge battery cell group and the terminal pair 6001 are connected to each other by bringing them into a conductive state. Thereby, the positive electrode terminal of the battery cell 6009 located most upstream in the discharge battery cell group is connected to either the terminal A1 or A2 of the terminal pair. In addition, the negative electrode terminal of the battery cell 6009 located on the most downstream side in the discharge battery cell group is connected to either the terminal A1 or A2 of the terminal pair, that is, the terminal not connected to the positive electrode terminal.

An OS transistor is preferably used as the transistor 6010. Since the OS transistor has a small off-state current, it is possible to reduce the amount of charge leaked from a battery cell that does not belong to the discharge battery cell group, and to suppress a decrease in capacity over time. In addition, the OS transistor is unlikely to break down when a high voltage is applied. Therefore, even when the output voltage of the discharge battery cell group is large, the battery cell 6009 to which the transistor 6010 to be turned off is connected and the terminal pair 6001 can be insulated.

In FIG. 20, the switching circuit 6005 includes a plurality of transistors 6013, a current control switch 6014, a bus 6015, and a bus 6016. The buses 6015 and 6016 are disposed between the plurality of transistors 6013 and the current control switch 6014. One of the sources or drains of the plurality of transistors 6013 is alternately connected to the buses 6015 and 6016 every other one. The other of the sources or drains of the plurality of transistors 6013 is connected between two adjacent battery cells 6009.

Note that, among the plurality of transistors 6013, the other of the source and the drain of the transistor 6013 located at the uppermost stream is connected to the positive terminal of the battery cell 6009 located at the uppermost stream of the battery portion 6008. In addition, among the plurality of transistors 6013, the other of the source and the drain of the transistor 6013 located on the most downstream side is connected to the negative electrode terminal of the battery cell 6009 located on the most downstream side of the battery portion 6008.

As the transistor 6010, an OS transistor is preferably used as the transistor 6010. Since the OS transistor has a small off-state current, it is possible to reduce the amount of charge leaked from a battery cell that does not belong to the rechargeable battery cell group, and to suppress a decrease in capacity over time. In addition, the OS transistor is unlikely to break down when a high voltage is applied. Therefore, even if the voltage for charging the rechargeable battery cell group is large, the battery cell 6009 to which the transistor 6013 to be turned off is connected and the terminal pair 6002 can be insulated.

The current control switch 6014 includes a switch pair 6017 and a switch pair 6018. One end of the switch pair 6017 is connected to the terminal B1. The other end of the switch pair 6017 is branched by two switches. One switch is connected to the bus 6015 and the other switch is connected to the bus 6016. One end of the switch pair 6018 is connected to the terminal B2. The other end of the switch pair 6018 is branched by two switches. One switch is connected to the bus 6015 and the other switch is connected to the bus 6016.

As the switches included in the switch pair 6017 and the switch pair 6018, OS transistors are preferably used as in the transistors 6010 and 6013.

The switching circuit 6005 connects the rechargeable battery cell group and the terminal pair 6002 by controlling the combination of on / off states of the transistor 6013 and the current control switch 6014 in accordance with the control signal S2.

As an example, the switching circuit 6005 connects the rechargeable battery cell group and the terminal pair 6002 as follows.

The switching circuit 6005 turns on the transistor 6013 connected to the positive terminal of the battery cell 6009 located at the most upstream in the charging battery cell group in response to the control signal S2 applied to the gates of the plurality of transistors 6010. . Further, the switching circuit 6005 conducts the changeover switch 151 connected to the negative terminal of the battery cell 6009 located most downstream in the charging battery cell group in response to the control signal S2 applied to the gates of the plurality of transistors 6010. Put it in a state.

The polarity of the voltage applied to the terminal pair 6002 can vary depending on the configuration of the discharge battery cell group connected to the terminal pair 6001 and the transformer circuit 6007. In addition, in order to flow a current in the direction of charging the rechargeable battery cell group, it is necessary to connect terminals having the same polarity between the terminal pair 6002 and the rechargeable battery cell group. Therefore, the current control switch 152 is controlled to switch the connection destination of the switch pair 6017 and the switch pair 6018 according to the polarity of the voltage applied to the terminal pair 6002 by the control signal S2.

As an example, a state in which a voltage such that the terminal B1 is a positive electrode and the terminal B2 is a negative electrode is applied to the terminal pair 6002 will be described. At this time, when the battery cell 6009 on the most downstream side of the battery unit 6008 is a rechargeable battery cell group, the switch pair 6017 is controlled to be connected to the positive terminal of the battery cell 6009 by the control signal S2. That is, the switch connected to the bus 6016 of the switch pair 6017 is turned on, and the switch connected to the bus 6015 of the switch pair 6017 is turned off. On the other hand, the switch pair 6018 is controlled to be connected to the negative terminal of the battery cell 6009 by the control signal S2. That is, the switch connected to the bus 6015 of the switch pair 6018 is turned on, and the switch connected to the bus 6016 of the switch pair 6018 is turned off. In this way, terminals having the same polarity are connected between the terminal pair 6002 and the rechargeable battery cell group. And the direction of the electric current which flows from the terminal pair 6002 is controlled so that it may become a direction which charges a charging battery cell group.

Further, the current control switch 152 may be included in the switching circuit 6004 instead of the switching circuit 6005. In this case, the polarity of the voltage applied to the terminal pair 6002 is controlled by controlling the polarity of the voltage applied to the terminal pair 6001 in accordance with the current control switch 6014 and the control signal S1. Current control switch 6014 controls the direction of current flowing from terminal pair 6002 to the rechargeable battery cell group.

FIG. 21 is a circuit diagram illustrating a configuration example of the switching circuit 6004 and the switching circuit 6005, which is different from FIG.

In FIG. 21, the switching circuit 6004 includes a plurality of transistor pairs 6021, a bus 6024, and a bus 6025. The bus 6024 is connected to the terminal A1. The bus 6025 is connected to the terminal A2. One ends of the plurality of transistor pairs 6021 are branched by a transistor 6022 and a transistor 6023, respectively. One of a source and a drain of the transistor 6022 is connected to the bus 6024. One of the source and the drain of the transistor 6023 is connected to the bus 6025. The other ends of the plurality of transistor pairs are connected between two adjacent battery cells 6009. Note that, among the plurality of transistor pairs 6021, the other end of the uppermost transistor pair 6021 is connected to the positive terminal of the battery cell 6009 located on the uppermost stream of the battery portion 6008. The other end of the transistor pair 6021 located on the most downstream side of the plurality of transistor pairs 6021 is connected to the negative electrode terminal of the battery cell 6009 located on the most downstream side of the battery portion 6008.

The switching circuit 6004 switches the connection destination of the transistor pair 6021 to either the terminal A1 or the terminal A2 by switching the conduction / non-conduction state of the transistor 6022 and the transistor 6023 according to the control signal S1. Specifically, when the transistor 6022 is in a conductive state, the transistor 6023 is in a non-conductive state, and the connection destination is the terminal A1. On the other hand, when the transistor 6023 is on, the transistor 6022 is off and the connection destination is the terminal A2. Which of the transistor 6022 and the transistor 6023 is turned on is determined by the control signal S1.

Two transistor pairs 6021 are used to connect the terminal pair 6001 and the discharge battery cell group. Specifically, the discharge battery cell group and the terminal pair 6001 are connected by determining the connection destination of the two transistor pairs 6021 based on the control signal S1. The connection destinations of the two transistor pairs 6021 are controlled by the control signal S1 so that one is the terminal A1 and the other is the terminal A2.

The switching circuit 6005 includes a plurality of transistor pairs 6031, a bus 6034, and a bus 6035. The bus 6034 is connected to the terminal B1. The bus 6035 is connected to the terminal B2. One ends of the plurality of transistor pairs 6031 are branched by a transistor 6032 and a transistor 6033, respectively. One end branched by the transistor 6032 is connected to the bus 6034. One end branched by the transistor 6033 is connected to the bus 6035. The other ends of the plurality of transistor pairs 6031 are connected between two adjacent battery cells 6009. Note that, among the plurality of transistor pairs 6031, the other end of the uppermost transistor pair 6031 is connected to the positive terminal of the battery cell 6009 located on the uppermost stream of the battery portion 6008. Further, among the plurality of transistor pairs 6031, the other end of the transistor pair 6031 located on the most downstream side is connected to the negative electrode terminal of the battery cell 6009 located on the most downstream side of the battery unit 6008.

The switching circuit 6005 switches the connection destination of the transistor pair 6031 to either the terminal B1 or the terminal B2 by switching the conduction / non-conduction state of the transistor 6032 and the transistor 6033 according to the control signal S2. Specifically, when the transistor 6032 is in a conductive state, the transistor 6033 is in a non-conductive state, and the connection destination is the terminal B1. On the other hand, when the transistor 6033 is on, the transistor 6032 is off and the connection destination is the terminal B2. Which of the transistor 6032 and the transistor 6033 is turned on is determined by the control signal S2.

Two transistor pairs 6031 are used to connect the terminal pair 6002 and the rechargeable battery cell group. Specifically, the connection destination of the two transistor pairs 6031 is determined based on the control signal S2, whereby the rechargeable battery cell group and the terminal pair 6002 are connected. The connection destinations of the two transistor pairs 6031 are controlled by the control signal S2 so that one is the terminal B1 and the other is the terminal B2.

The connection destination of each of the two transistor pairs 6031 is determined by the polarity of the voltage applied to the terminal pair 6002. Specifically, when a voltage is applied to the terminal pair 6002 so that the terminal B1 is a positive electrode and the terminal B2 is a negative electrode, the transistor pair 6031 on the upstream side is in a conductive state and the transistor 6033 is in a nonconductive state. It is controlled by the control signal S2 so as to be in a state. On the other hand, the transistor pair 6031 on the downstream side is controlled by the control signal S2 so that the transistor 6033 is turned on and the transistor 6032 is turned off. In addition, when a voltage is applied to the terminal pair 6002 so that the terminal B1 is a negative electrode and the terminal B2 is a positive electrode, the transistor pair 6031 on the upstream side is in a conductive state and the transistor 6032 is in a nonconductive state. It is controlled by the control signal S2. On the other hand, the transistor pair 6031 on the downstream side is controlled by the control signal S2 so that the transistor 6032 is conductive and the transistor 6033 is non-conductive. In this way, terminals having the same polarity are connected between the terminal pair 6002 and the rechargeable battery cell group. And the direction of the electric current which flows from the terminal pair 6002 is controlled so that it may become a direction which charges a charging battery cell group.

A transformation control circuit 6006 controls the operation of the transformation circuit 6007. The transformation control circuit 6006 generates a transformation signal S3 for controlling the operation of the transformation circuit 6007 based on the number of battery cells 6009 included in the discharge battery cell group and the number of battery cells 6009 included in the charge battery cell group. And output to the transformer circuit 6007.

When the number of battery cells 6009 included in the discharge battery cell group is larger than the number of battery cells 6009 included in the charge battery cell group, an excessively large charge voltage is applied to the charge battery cell group. Need to prevent. Therefore, the transformation control circuit 6006 outputs a transformation signal S3 for controlling the transformation circuit 6007 so as to step down the discharge voltage (Vdis) within a range in which the rechargeable battery cell group can be charged.

Further, when the number of battery cells 6009 included in the discharge battery cell group is equal to or less than the number of battery cells 6009 included in the charge battery cell group, a charging voltage necessary for charging the charge battery cell group is ensured. There is a need. Therefore, the transformation control circuit 6006 outputs a transformation signal S3 that controls the transformation circuit 6007 so as to boost the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group.

Note that the voltage value for the excessive charging voltage can be determined in consideration of the product specifications of the battery cell 6009 used in the battery unit 6008. The voltage stepped up and stepped down by the transformer circuit 6007 is applied to the terminal pair 6002 as a charging voltage (Vcha).

Here, an operation example of the transformation control circuit 6006 in this embodiment will be described with reference to FIGS. 22A to 22C are conceptual diagrams for explaining an operation example of the transformation control circuit 6006 corresponding to the discharge battery cell group and the charge battery cell group described in FIGS. 19A to 19C. FIG. 22A to 22C show the battery control unit 6041. FIG. As described above, the battery control unit 6041 includes the terminal pair 6001, the terminal pair 6002, the switching control circuit 6003, the switching circuit 6004, the switching circuit 6005, the transformation control circuit 6006, and the transformation circuit 6007. The

In the example shown in FIG. 22A, as described with reference to FIG. 19A, three continuous high-voltage cells a to c and one low-voltage cell d are connected in series. In this case, as described with reference to FIG. 19A, the switching control circuit 6003 determines the high voltage cells a to c as the discharge battery cell group and the low voltage cell d as the charge battery cell group. Then, the transformation control circuit 6006 determines the discharge voltage (Vdis) based on the ratio of the number of battery cells 6009 included in the charge electric cell group when the number of battery cells 6009 included in the discharge battery cell group is used as a reference. The step-up / step-down ratio N is calculated.

When the number of battery cells 6009 included in the discharge battery cell group is larger than the number of battery cells 6009 included in the charge battery cell group, if the discharge voltage is directly applied to the terminal pair 6002 without being transformed, the charge battery An excessive voltage may be applied to the battery cell 6009 included in the cell group via the terminal pair 6002. Therefore, in the case shown in FIG. 22A, it is necessary to step down the charging voltage (Vcha) applied to the terminal pair 6002 below the discharging voltage. Furthermore, in order to charge the charging battery cell group, the charging voltage needs to be larger than the total voltage of the battery cells 6009 included in the charging battery cell group. Therefore, the transformation control circuit 6006 has a step-up / step-down ratio N larger than the ratio of the number of battery cells 6009 included in the charging electric cell group when the number of battery cells 6009 included in the discharge battery cell group is used as a reference. Set.

The transformation control circuit 6006 sets the step-up / step-down ratio N to 1 to the ratio of the number of battery cells 6009 included in the charging electric cell group when the number of battery cells 6009 included in the discharge battery cell group is used as a reference. It is preferable to increase it by about 10%. At this time, the charging voltage is larger than the voltage of the charging battery cell group, but in practice, the charging voltage is equal to the voltage of the charging battery cell group. However, in order to make the voltage of the charging battery cell group equal to the charging voltage in accordance with the step-up / down ratio N, the transformation control circuit 6006 passes a current for charging the charging battery cell group. This current is a value set in the transformation control circuit 6006.

In the example shown in FIG. 22A, since the number of battery cells 6009 included in the discharge battery cell group is three and the number of battery cells 6009 included in the charge battery cell group is one, the transformation control circuit In 6006, a value slightly larger than 1/3 is calculated as the step-up / step-down ratio N. Then, the transformation control circuit 6006 steps down the discharge voltage according to the step-up / step-down ratio N, and outputs a transformation signal S3 that converts it to a charging voltage to the transformation circuit 6007. Then, the transformer circuit 6007 applies the charging voltage transformed according to the transformation signal S3 to the terminal pair 6002. Then, the battery cell 6009 included in the charged battery cell group is charged by the charging voltage applied to the terminal pair 6002.

Also in the examples shown in FIGS. 22B and 22C, the step-up / step-down ratio N is calculated as in FIG. 22A. In the examples shown in FIGS. 22B and 22C, the number of battery cells 6009 included in the discharge battery cell group is equal to or less than the number of battery cells 6009 included in the charge battery cell group. N is 1 or more. Therefore, in this case, the transformation control circuit 6006 outputs a transformation signal S3 that boosts the discharge voltage and converts it into a received voltage.

The transformer circuit 6007 converts the discharge voltage applied to the terminal pair 6001 into a charge voltage based on the transform signal S3. Then, the transformer circuit 6007 applies the converted charging voltage to the terminal pair 6002. Here, the transformer circuit 6007 electrically insulates between the terminal pair 6001 and the terminal pair 6002. Thereby, the transformer circuit 6007 has the absolute voltage of the negative electrode terminal of the battery cell 6009 located most downstream in the discharge battery cell group and the negative voltage terminal of the battery cell 6009 located most downstream in the charge battery cell group. Prevents short circuit due to difference from absolute voltage. Furthermore, as described above, the transformer circuit 6007 converts the discharge voltage, which is the total voltage of the discharge battery cell group, into a charge voltage based on the transform signal S3.

In addition, for example, an insulating DC (Direct Current) -DC converter or the like can be used for the transformer circuit 6007. In this case, the transformation control circuit 6006 controls the charging voltage converted by the transformation circuit 6007 by outputting a signal for controlling the on / off ratio (duty ratio) of the isolated DC-DC converter as the transformation signal S3. .

Insulated DC-DC converters include flyback method, forward method, RCC (Ringing Choke Converter) method, push-pull method, half-bridge method, and full-bridge method. An appropriate method is selected according to the size.

FIG. 23 shows a configuration of a transformer circuit 6007 using an insulated DC-DC converter. The insulated DC-DC converter 6051 includes a switch unit 6052 and a transformer unit 6053. The switch unit 6052 is a switch for switching on / off the operation of the insulated DC-DC converter, and is realized by using, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a bipolar transistor, or the like. In addition, the switch unit 6052 periodically switches between the on state and the off state of the insulated DC-DC converter 6051 based on the transform signal S3 that is output from the transform control circuit 6006 and controls the on / off ratio. Note that the switch unit 6052 can have various configurations depending on the type of the insulation type DC-DC converter used. Transformer 6053 converts the discharge voltage applied from terminal pair 6001 into a charge voltage. Specifically, the transformer unit 6053 operates in conjunction with the on / off state of the switch unit 6052, and converts the discharge voltage into a charge voltage according to the on / off ratio. This charging voltage increases as the time in which the switch unit 6052 is turned on becomes longer in the switching cycle. On the other hand, the charging voltage becomes smaller as the time for which the on state is turned on is shorter in the switching period of the switch unit 6052. Note that in the case of using an insulated DC-DC converter, the terminal pair 6001 and the terminal pair 6002 can be insulated from each other inside the transformer unit 6053.

A processing flow of the power storage device 6000 in the present embodiment will be described with reference to FIG. FIG. 24 is a flowchart illustrating a process flow of the power storage device 6000.

First, the power storage device 6000 acquires the voltage measured for each of the plurality of battery cells 6009 (step S001). Then, power storage device 6000 determines whether or not an operation start condition for aligning the voltages of the plurality of battery cells 6009 is satisfied (step S002). The start condition can be, for example, whether or not the difference between the maximum value and the minimum value of the voltage measured for each of the plurality of battery cells 6009 is a predetermined threshold value or more. When this start condition is not satisfied (step S002: NO), the voltage of each battery cell 6009 is balanced, and thus the power storage device 6000 does not perform the subsequent processing. On the other hand, when the start condition is satisfied (step S002: YES), power storage device 6000 executes a process for aligning the voltages of battery cells 6009. In this process, the power storage device 6000 determines whether each battery cell 6009 is a high voltage cell or a low voltage cell based on the measured voltage for each cell (step S003). Then, the power storage device 6000 determines a discharge battery cell group and a charge battery cell group based on the determination result (step S004). Furthermore, power storage device 6000 provides a control signal S1 for setting the determined discharge battery cell group as a connection destination of terminal pair 6001, and a control signal S2 for setting the determined charge battery cell group as a connection destination of terminal pair 6002. Generate (step S005). The power storage device 6000 outputs the generated control signal S1 and control signal S2 to the switching circuit 6004 and the switching circuit 6005, respectively. Then, the switching circuit 6004 connects the terminal pair 6001 and the discharge battery cell group, and the switching circuit 6005 connects the terminal pair 6002 and the discharge battery cell group (step S006). The power storage device 6000 generates the transformation signal S3 based on the number of battery cells 6009 included in the discharge battery cell group and the number of battery cells 6009 included in the charge battery cell group (step S007). Then, the power storage device 6000 converts the discharge voltage applied to the terminal pair 6001 into a charging voltage based on the transformation signal S3 and applies it to the terminal pair 6002 (step S008). Thereby, the electric charge of the discharge battery cell group is moved to the charge battery cell group.

Further, in the flowchart of FIG. 24, a plurality of steps are described in order, but the execution order of each step is not limited to the description order.

As described above, according to the present embodiment, when the charge is transferred from the discharge battery cell group to the charge battery cell group, the charge is temporarily accumulated from the discharge battery cell group and then released to the charge battery cell group as in the capacitor system. No configuration is required. Thereby, the charge transfer efficiency per unit time can be improved. Further, the discharge battery cell group and the charge battery cell group are individually switched by the switching circuit 6004 and the switching circuit 6005.

Furthermore, based on the number of battery cells 6009 included in the discharge battery cell group and the number of battery cells 6009 group included in the charge battery cell group by the transformer circuit 6007, the discharge voltage applied to the terminal pair 6001 is changed to the charge voltage. And applied to the terminal pair 6002. Thereby, no matter how the discharge-side and charge-side battery cells 6009 are selected, the movement of charges can be realized without any problem.

Further, by using an OS transistor for the transistor 6010 and the transistor 6013, the amount of charge leaked from the battery cell 6009 that does not belong to the charge battery cell group and the discharge battery cell group can be reduced. Thereby, the capacity | capacitance fall of the battery cell 6009 which does not contribute to charge and discharge can be suppressed. In addition, the OS transistor has less variation in characteristics with respect to heat than the Si transistor. Thereby, even if the temperature of the battery cell 6009 rises, normal operation such as switching between the conductive state and the non-conductive state according to the control signals S1 and S2 can be performed.

(Embodiment 5)
In this embodiment, an example in which a storage battery having flexibility is mounted on an electronic device will be described.

FIG. 25 illustrates an example in which the flexible storage battery described in Embodiment 2 is mounted on an electronic device. As an electronic device to which a power storage device having a flexible shape is applied, for example, a television device (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (Also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, a sound reproduction device, a large game machine such as a pachinko machine, and the like.

In addition, a power storage device having a flexible shape can be incorporated along a curved surface of an inner wall or an outer wall of a house or a building, or an interior or exterior of an automobile.

FIG. 25A illustrates an example of a mobile phone. A mobile phone 7400 is provided with a display portion 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone 7400 includes a power storage device 7407.

FIG. 25B illustrates a state where the mobile phone 7400 is bent. When the cellular phone 7400 is deformed by an external force to bend the whole, the power storage device 7407 provided therein is also curved. In addition, FIG. 25C illustrates a state of the power storage device 7407 bent at that time. The power storage device 7407 is a thin storage battery. The power storage device 7407 is fixed in a bent state. Note that the power storage device 7407 includes a lead electrode 7408 electrically connected to the current collector 7409. For example, the current collector 7409 is a copper foil, which is partly alloyed with gallium to improve adhesion with the active material layer in contact with the current collector 7409, and reliability in a state where the power storage device 7407 is bent. Has a high configuration.

FIG. 25D illustrates an example of a bangle display device. A portable display device 7100 includes a housing 7101, a display portion 7102, operation buttons 7103, and a power storage device 7104. FIG. 25E shows the state of the power storage device 7104 bent. When the power storage device 7104 is bent and attached to the user's arm, the housing is deformed and the curvature of part or all of the power storage device 7104 changes. Note that the curvature at a given point of the curve expressed by the value of the radius of the corresponding circle is the curvature radius, and the reciprocal of the curvature radius is called the curvature. Specifically, part or all of the main surface of the housing or the power storage device 7104 changes within a radius of curvature of 40 mm to 150 mm. High reliability can be maintained if the radius of curvature of the main surface of the power storage device 7104 is in the range of 40 mm to 150 mm.

FIG. 25F illustrates an example of a wristwatch-type portable information terminal. A portable information terminal 7200 includes a housing 7201, a display portion 7202, a band 7203, a buckle 7204, operation buttons 7205, an input / output terminal 7206, and the like.

The portable information terminal 7200 can execute various applications such as a mobile phone, electronic mail, text browsing and creation, music playback, Internet communication, and computer games.

The display portion 7202 is provided with a curved display surface, and display can be performed along the curved display surface. The display portion 7202 includes a touch sensor and can be operated by touching the screen with a finger, a stylus, or the like. For example, an application can be started by touching an icon 7207 displayed on the display portion 7202.

The operation button 7205 can have various functions such as power on / off operation, wireless communication on / off operation, manner mode execution and release, and power saving mode execution and release, in addition to time setting. . For example, the function of the operation button 7205 can be freely set by an operation system incorporated in the portable information terminal 7200.

In addition, the portable information terminal 7200 can perform short-range wireless communication with a communication standard. For example, it is possible to talk hands-free by communicating with a headset capable of wireless communication.

In addition, the portable information terminal 7200 includes an input / output terminal 7206, and can directly exchange data with other information terminals via a connector. Charging can also be performed through the input / output terminal 7206. Note that the charging operation may be performed by wireless power feeding without using the input / output terminal 7206.

The display portion 7202 of the portable information terminal 7200 includes a power storage device including the electrode member of one embodiment of the present invention. For example, the power storage device 7104 illustrated in FIG. 25E can be incorporated in the housing 7201 in a curved state or in the band 7203 in a bendable state.

FIG. 25G illustrates an example of an armband display device. The display device 7300 includes the display portion 7304 and includes the power storage device of one embodiment of the present invention. In addition, the display device 7300 can include a touch sensor in the display portion 7304 and can function as a portable information terminal.

The display portion 7304 has a curved display surface, and can perform display along the curved display surface. In addition, the display device 7300 can change the display status through short-range wireless communication that is a communication standard.

In addition, the display device 7300 includes an input / output terminal, and can directly exchange data with another information terminal via a connector. Charging can also be performed via an input / output terminal. Note that the charging operation may be performed by wireless power feeding without using the input / output terminal.

This embodiment can be implemented in appropriate combination with any of the other embodiments.

(Embodiment 6)
In this embodiment, an example of an electronic device in which the power storage device can be mounted is described.

FIG. 26A and FIG. 26B illustrate an example of a tablet terminal that can be folded. A tablet terminal 9600 illustrated in FIGS. 26A and 26B includes a housing 9630a, a housing 9630b, a movable portion 9640 connecting the housing 9630a and the housing 9630b, a display portion 9631a, and a display portion 9631b. A display portion 9631, a display mode switching switch 9626, a power switch 9627, a power saving mode switching switch 9625, a fastener 9629, and an operation switch 9628 are provided. FIG. 26A shows a state in which the tablet terminal 9600 is opened, and FIG. 26B shows a state in which the tablet terminal 9600 is closed.

In addition, the tablet terminal 9600 includes a power storage unit 9635 inside the housing 9630a and the housing 9630b. The power storage unit 9635 is provided across the housing 9630a and the housing 9630b through the movable portion 9640.

Part of the display portion 9631 a can be a touch panel region 9632 a and data can be input when a displayed operation key 9638 is touched. Note that in the display portion 9631a, for example, a structure in which half of the regions have a display-only function and a structure in which the other half has a touch panel function is shown, but the structure is not limited thereto. The entire region of the display portion 9631a may have a touch panel function. For example, the entire surface of the display portion 9631a can display keyboard buttons to serve as a touch panel, and the display portion 9631b can be used as a display screen.

Further, in the display portion 9631b, as in the display portion 9631a, part of the display portion 9631b can be a touch panel region 9632b. Further, a keyboard button can be displayed on the display portion 9631b by touching a position where the keyboard display switching button 9539 on the touch panel is displayed with a finger or a stylus.

Touch input can be performed simultaneously on the touch panel region 9632a and the touch panel region 9632b.

A display mode switching switch 9626 can switch a display direction such as a vertical display or a horizontal display, and can select a monochrome display or a color display. The power saving mode change-over switch 9625 can optimize the display luminance in accordance with the amount of external light in use detected by an optical sensor incorporated in the tablet terminal 9600. The tablet terminal may include not only an optical sensor but also other detection devices such as a gyroscope, an acceleration sensor, and other sensors that detect inclination.

FIG. 26A illustrates an example in which the display areas of the display portion 9631b and the display portion 9631a are the same; however, there is no particular limitation, and one size may differ from the other size, and the display quality may also be different. May be different. For example, one display panel may be capable of displaying images with higher definition than the other.

FIG. 26B illustrates a closed state, in which the tablet terminal includes a charge / discharge control circuit 9634 including a housing 9630, a solar battery 9633, and a DCDC converter 9636. Further, as the power storage unit 9635, the power storage unit according to one embodiment of the present invention is used.

Note that since the tablet terminal 9600 can be folded in two, the housing 9630a and the housing 9630b can be folded so as to overlap when not in use. By folding, the display portion 9631a and the display portion 9631b can be protected; thus, durability of the tablet terminal 9600 can be improved. Further, the power storage unit 9635 using the power storage unit of one embodiment of the present invention has flexibility, and thus the charge / discharge capacity is hardly reduced even when bending and stretching are repeated. Therefore, a tablet terminal with excellent reliability can be provided.

In addition, the tablet terminal shown in FIGS. 26A and 26B has a function for displaying various information (still images, moving images, text images, etc.), a calendar, a date, or a time. A function for displaying on the display unit, a touch input function for performing touch input operation or editing of information displayed on the display unit, a function for controlling processing by various software (programs), and the like can be provided.

Electric power can be supplied to the touch panel, the display unit, the video signal processing unit, or the like by the solar battery 9633 mounted on the surface of the tablet terminal. Note that the solar cell 9633 can be provided on one or both surfaces of the housing 9630 and the battery 9635 can be charged efficiently. Note that as the power storage unit 9635, when a lithium ion battery is used, there is an advantage that the size can be reduced.

The structure and operation of the charge / discharge control circuit 9634 illustrated in FIG. 26B are described with reference to a block diagram in FIG. FIG. 26C illustrates the solar battery 9633, the power storage unit 9635, the DCDC converter 9636, the converter 9637, the switches SW1 to SW3, and the display portion 9631. The power storage unit 9635, the DCDC converter 9636, the converter 9637, and the switches SW1 to SW3 are illustrated. SW3 corresponds to the charge / discharge control circuit 9634 shown in FIG.

First, an example of operation in the case where power is generated by the solar battery 9633 using external light is described. The power generated by the solar battery is boosted or lowered by the DCDC converter 9636 so as to be a voltage for charging the power storage unit 9635. When power from the solar cell 9633 is used for the operation of the display portion 9631, the switch SW1 is turned on, and the converter 9637 increases or decreases the voltage required for the display portion 9631. In the case where display on the display portion 9631 is not performed, the power storage unit 9635 may be charged by turning off SW1 and turning on SW2.

Note that the solar battery 9633 is described as an example of the power generation unit, but is not particularly limited, and the power storage unit 9635 is charged by another power generation unit such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). It may be. For example, a non-contact power transmission module that wirelessly (contactlessly) transmits and receives power for charging and other charging means may be combined.

FIG. 27 illustrates an example of another electronic device. In FIG 27, a display device 8000 is an example of an electronic device including the power storage device 8004 according to one embodiment of the present invention. Specifically, the display device 8000 corresponds to a display device for TV broadcast reception, and includes a housing 8001, a display portion 8002, a speaker portion 8003, a power storage device 8004, and the like. A power storage device 8004 according to one embodiment of the present invention is provided inside the housing 8001. The display device 8000 can receive power from a commercial power supply. Alternatively, the display device 8000 can use power stored in the power storage device 8004. Thus, the display device 8000 can be used by using the power storage device 8004 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

A display portion 8002 includes a liquid crystal display device, a light-emitting device including a light-emitting element such as an organic EL element, an electrophoretic display device, a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), and an FED (Field Emission Display). A semiconductor display device such as) can be used.

The display device includes all information display devices such as a personal computer and an advertisement display in addition to a TV broadcast reception.

In FIG 27, a stationary lighting device 8100 is an example of an electronic device including the power storage device 8103 according to one embodiment of the present invention. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a power storage device 8103, and the like. 27 illustrates the case where the power storage device 8103 is provided inside the ceiling 8104 where the housing 8101 and the light source 8102 are installed, the power storage device 8103 is provided inside the housing 8101. May be. The lighting device 8100 can receive power from a commercial power supply. Alternatively, the lighting device 8100 can use power stored in the power storage device 8103. Therefore, the lighting device 8100 can be used by using the power storage device 8103 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

Note that although a stationary lighting device 8100 provided on the ceiling 8104 is illustrated in FIG. 27, the power storage device according to one embodiment of the present invention is not provided on the ceiling 8104, for example, on the sidewall 8105, the floor 8106, the window 8107, or the like. It can be used for a stationary lighting device provided, or can be used for a desktop lighting device or the like.

The light source 8102 can be an artificial light source that artificially obtains light using electric power. Specifically, discharge lamps such as incandescent bulbs and fluorescent lamps, and light emitting elements such as LEDs and organic EL elements are examples of the artificial light source.

In FIG 27, an air conditioner including an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using the power storage device 8203 according to one embodiment of the present invention. Specifically, the indoor unit 8200 includes a housing 8201, an air outlet 8202, a power storage device 8203, and the like. FIG. 27 illustrates the case where the power storage device 8203 is provided in the indoor unit 8200, but the power storage device 8203 may be provided in the outdoor unit 8204. Alternatively, the power storage device 8203 may be provided in both the indoor unit 8200 and the outdoor unit 8204. The air conditioner can receive power from a commercial power supply. Alternatively, the air conditioner can use power stored in the power storage device 8203. In particular, in the case where the power storage device 8203 is provided in both the indoor unit 8200 and the outdoor unit 8204, the power storage device 8203 according to one embodiment of the present invention can be disconnected even when power supply from a commercial power source cannot be received due to a power failure or the like. By using it as a power failure power supply, an air conditioner can be used.

In FIG. 27, a separate type air conditioner composed of an indoor unit and an outdoor unit is illustrated, but an integrated air conditioner having the functions of the indoor unit and the outdoor unit in one housing is shown. The power storage device according to one embodiment of the present invention can also be used.

In FIG 27, an electric refrigerator-freezer 8300 is an example of an electronic device including the power storage device 8304 according to one embodiment of the present invention. Specifically, the electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator door 8302, a freezer door 8303, a power storage device 8304, and the like. In FIG. 27, the power storage device 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 can receive power from a commercial power supply. Alternatively, the electric refrigerator-freezer 8300 can use power stored in the power storage device 8304. Therefore, the electric refrigerator-freezer 8300 can be used by using the power storage device 8304 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

Note that among the electronic devices described above, a high-frequency heating device such as a microwave oven and an electronic device such as an electric rice cooker require high power in a short time. Therefore, by using the power storage device according to one embodiment of the present invention as an auxiliary power source for assisting electric power that cannot be supplied by a commercial power source, a breaker of the commercial power source can be prevented from falling when the electronic device is used.

In addition, when the electronic equipment is not used, especially during the time when the ratio of the actually used power amount (referred to as the power usage rate) is low in the total power amount that can be supplied by the commercial power supply source. By storing electric power in the apparatus, it is possible to suppress an increase in the power usage rate outside the above time period. For example, in the case of the electric refrigerator-freezer 8300, electric power is stored in the power storage device 8304 at night when the temperature is low and the refrigerator door 8302 and the refrigerator door 8303 are not opened and closed. In the daytime when the temperature rises and the refrigerator door 8302 and the freezer door 8303 are opened and closed, the power storage device 8304 is used as an auxiliary power source, so that the daytime power usage rate can be kept low.

This embodiment can be implemented in appropriate combination with any of the other embodiments.

(Embodiment 7)
In this embodiment, an example in which a power storage device is mounted on a vehicle is shown.

When the power storage device is mounted on a vehicle, a next-generation clean energy vehicle such as a hybrid vehicle (HEV), an electric vehicle (EV), or a plug-in hybrid vehicle (PHEV) can be realized.

FIG. 28 illustrates a vehicle using one embodiment of the present invention. A car 8400 illustrated in FIG. 28A is an electric car using an electric motor as a power source for traveling. Or it is a hybrid vehicle which can select and use an electric motor and an engine suitably as a motive power source for driving | running | working. By using one embodiment of the present invention, a vehicle having a long cruising distance can be realized. The automobile 8400 includes a power storage device. The power storage device can not only drive an electric motor but also supply power to a light-emitting device such as a headlight 8401 or a room light (not shown).

The power storage device can supply power to a display device such as a speedometer or a tachometer included in the automobile 8400. The power storage device can supply power to a semiconductor device such as a navigation system included in the automobile 8400.

A car 8500 illustrated in FIG. 28B can charge a power storage device included in the car 8500 by receiving power from an external charging facility by a plug-in method, a non-contact power feeding method, or the like. FIG. 28B illustrates a state where charging is performed from the ground-mounted charging device 8021 to the power storage device mounted on the automobile 8500 through the cable 8022. When charging, the charging method, connector standard, and the like may be appropriately performed by a predetermined method such as CHAdeMO (registered trademark) or a combo. The charging device 8021 may be a charging station provided in a commercial facility, or may be a household power source. For example, the power storage device 8024 mounted on the automobile 8500 can be charged by power supply from the outside by plug-in technology. Charging can be performed by converting AC power into DC power via a converter such as an ACDC converter.

In addition, although not shown, the power receiving device can be mounted on the vehicle, and electric power can be supplied from the ground power transmitting device in a contactless manner and charged. In the case of this non-contact power supply method, charging can be performed not only when the vehicle is stopped but also during traveling by incorporating a power transmission device on a road or an outer wall. In addition, this non-contact power feeding method may be used to transmit and receive power between vehicles. Furthermore, a solar battery may be provided in the exterior portion of the vehicle, and the power storage device may be charged when the vehicle is stopped or traveling. An electromagnetic induction method or a magnetic field resonance method can be used for such non-contact power supply.

According to one embodiment of the present invention, cycle characteristics of a power storage device can be improved, and reliability can be improved. According to one embodiment of the present invention, characteristics of the power storage device can be improved, and thus the power storage device itself can be reduced in size and weight. If the power storage device itself can be reduced in size and weight, the cruising distance can be improved because it contributes to weight reduction of the vehicle. In addition, a power storage device mounted on a vehicle can be used as a power supply source other than the vehicle. In this case, it is possible to avoid using a commercial power source at the peak of power demand.

This embodiment can be implemented in appropriate combination with any of the other embodiments.

In this example, the results of measuring the characteristics of a battery using the method described in Embodiment 1 and manufacturing an active material and using an electrode including the active material will be described.

<Synthesis of lithium manganese composite oxide>
First, Li ₂ CO ₃ , MnCO ₃ , and NiO are used as starting materials, and the ratio (molar ratio) of the starting materials to be weighed is Li ₂ CO ₃ : MnCO ₃ : NiO = 0.84: 0.8062: Weighed out to be 0.318. Next, ethanol was added to the starting material and mixed using a bead mill. The mixing process was performed by rotating the processing chamber of the bead mill at a peripheral speed of 10 m / sec and a mixing time of 30 minutes to obtain a mixed raw material.

Next, the mixed raw material was subjected to heat treatment. By performing the heat treatment in an air atmosphere at a heating temperature of 75 ° C., ethanol contained in the mixed mixed raw material was evaporated to obtain a mixed raw material.

Next, the mixed raw material was put into a crucible and fired. The firing treatment was performed in an air gas (dry air) atmosphere at a flow rate of 10 L / min, with a firing temperature of 1000 ° C. and a firing time of 10 hours, thereby synthesizing a lithium manganese composite oxide.

Next, a crushing treatment was performed to unsinter the lithium manganese composite oxide in which the primary particles were sintered. The pulverization treatment is performed by adding ethanol to the sintered lithium manganese composite oxide, rotating the bead mill treatment chamber at a peripheral speed of 4 m / sec, and performing the pulverization and pulverization time of 10 hours. A lithium manganese composite oxide was obtained.

Next, heat treatment was performed on the lithium manganese composite oxide after the pulverization treatment. By performing the heat treatment in an air atmosphere at a heating temperature of 75 ° C., ethanol contained in the mixed mixed material was evaporated to obtain a powdery lithium manganese composite oxide.

Next, the lithium manganese composite oxide after the heat treatment was put into the crucible, and the firing treatment was performed again. The firing process is performed in an air gas (dry air) atmosphere at a flow rate of 10 L / min, with a firing temperature of 800 ° C. and a firing time of 3 hours. Synthesized.

This lithium manganese composite oxide is represented by the composition formula Li _1.68 Mn _0.8062 Ni _0.318 O ₃ , but may deviate from this composition.

<Graphene oxide coating process>
Next, a layer containing carbon was formed on the obtained lithium manganese composite oxide. First, a graphene oxide dispersion solution was prepared by kneading using a kneader at a ratio of 40 g of water to 4 g of graphene oxide. Next, 200 g of lithium manganese composite oxide was added to the prepared aqueous dispersion, 100 g of water was further added, and kneading was performed twice. For the kneading, a kneader was used, the number of revolutions was 80 rpm, and the kneading time was 30 minutes for one kneading, and was repeated twice. The obtained mixture was dried at 70 ° C. using a ventilation drying furnace, and then crushed in an alumina mortar to obtain a lithium manganese composite oxide coated with graphene oxide.

<Graphene oxide reduction process>
Next, the graphene oxide coated on the surface of the lithium manganese composite oxide was reduced. Ascorbic acid was used as the reducing agent, and an aqueous ethanol solution having a concentration of 80% was used as the solvent. Ascorbic acid 16.87 wt% and lithium hydroxide 3.9 wt% were added to the weight of the lithium manganese composite oxide coated with graphene oxide to prepare a reducing solution. The obtained powder was put into a reducing solution and treated at 60 ° C. for 3 hours for reduction. Next, the obtained solution was filtered by suction filtration. For filtration, a filter paper having a particle retention capacity of 1 μm was used. Then, it wash | cleaned and filtered again. Next, the powder obtained by filtration was pulverized in a mortar. Thereafter, drying was performed at 170 ° C. under reduced pressure for 10 hours. Through the above steps, a powdered lithium manganese composite oxide having graphene formed on the surface was produced.

<Production of electrode>
Next, an electrode was fabricated using a powdered lithium manganese composite oxide having graphene formed on the surface. Lithium manganese composite oxide was used as the active material, acetylene black (AB) was used as the conductive assistant, and PVdF was used as the binder.

First, PVdF and AB were kneaded with NMP (N-methyl-2-pyrrolidone), which is a polar solvent. The number of rotations of kneading was 2000 rpm, and the time of kneading was 5 minutes for one time. Further, Sample C was added as an active material and kneaded. The number of kneading revolutions was 2000 rpm, and the kneading time was 5 times, once for 5 minutes. Furthermore, NMP was added and kneaded. The number of kneading revolutions was 2000 rpm, and the kneading time was 10 minutes for each kneading, which was repeated twice. Through the above steps, a slurry-like electrode mixture composition was obtained. The composition of the electrode mixture composition was active material: AB: PVdF = 90: 5: 5 by weight ratio.

Next, the electrode mixture composition was applied onto an aluminum foil as a current collector. The aluminum foil surface was previously undercoated. Then, it dried at 80 degreeC for 30 minutes with the ventilation drying furnace.

Thereafter, further heat treatment was performed. As a heat treatment condition, a treatment was performed in a reduced pressure atmosphere (1 KPa) at 250 ° C. for 10 hours. Through the above steps, an electrode having “a particle having a lithium manganese composite oxide” which is one embodiment of the present invention was obtained.

<Section TEM photo>
Next, a TEM image using a spherical aberration correction function was observed for the lithium manganese composite oxide taken out by disassembling the electrode. Note that a combined analysis image of a bright field image and a diffraction pattern by TEM observation is referred to as a high resolution TEM image. A high-resolution TEM image using the spherical aberration correction function is particularly called a Cs-corrected high-resolution TEM image. For acquisition of the Cs-corrected high resolution TEM image, an atomic resolution analytical electron microscope JEM-ARM200F manufactured by JEOL Ltd. was used. The acceleration voltage was 200 kV.

FIG. 29A shows a partially enlarged photograph of the lithium manganese composite oxide, and FIG. 29B shows an enlarged photograph in a one-dot dashed frame in FIG. 29A. The stacked structure including atoms that appear white in FIG. 29A includes a layer containing manganese. It was confirmed that the crystal direction was shifted across the surface indicated by the arrow in the figure.

Layers A to D indicated by broken lines in FIG. 29B are layers in which a stacking fault has occurred. The region on the right side of the layer A is aligned in the 110 direction aligned along the white solid line, and in the 100 direction aligned along the white solid line of the region sandwiched between the layers A-B. It was confirmed that The region sandwiched between the layers AB was aligned in the 100 direction, and the region sandwiched between the layers BC was aligned in the 110 direction. The region sandwiched between the layers BC was aligned in the 110 direction, and the region sandwiched between the layers CD was aligned in the 100 direction. Further, the region sandwiched between the layers C-D was aligned in the 100 direction, and the region on the left side of the layer D was aligned in the 110 direction. Therefore, as shown in FIGS. 29A and 29B, it was confirmed that the manganese layer of the lithium manganese composite oxide had stacking faults.

In this example, an electrode including an active material according to one embodiment of the present invention is manufactured, a half cell using the electrode is manufactured, and a result of measuring cycle characteristics is described.

Table 1 shows the material ratio of the active materials used in this example.

First, Li ₂ CO ₃ , MnCO ₃ , and NiO were used as starting materials, and the proportions (molar ratio) of the starting materials were weighed so as to be the proportions shown in Table 1, and are shown in Example 1. Samples 2-A to 2-I made of a powdered lithium manganese composite oxide were produced using the same production method as the sample.

Next, a method for producing an electrode will be described. First, polyvinylidene fluoride (PVdF) as a binder and acetylene black (AB) as a conductive auxiliary agent were kneaded with NMP (N-methyl-2-pyrrolidone) as a polar solvent. The number of rotations of kneading was 2000 rpm, and the time of kneading was 5 minutes for one time. Further, Samples 2-A to 2-I were added as active materials and kneaded. The number of kneading revolutions was 2000 rpm, and the kneading time was 5 times, once for 5 minutes. Furthermore, NMP was added and kneaded. The number of kneading revolutions was 2000 rpm, and the kneading time was 10 minutes for each kneading, which was repeated twice. Through the above steps, a slurry-like electrode mixture composition was obtained. The composition of the electrode mixture composition was set to Sample 2-A to Sample 2-I: AB: PVdF = 90: 5: 5 by weight ratio.

Next, the electrode mixture composition was applied onto an aluminum foil as a current collector. The aluminum foil surface was previously undercoated. Then, it dried at 80 degreeC for 30 minutes with the ventilation drying furnace. The electrodes obtained through the above steps are referred to as electrodes 2-A to 2-I, respectively.

Next, the half cell 2-A to the half cell 2-I were manufactured by using the electrodes 2-A to 2-I as the positive electrodes, respectively. A coin cell was used as the cell. Moreover, lithium was used for the counter electrode of the half cell. As the electrolyte, LiPF ₆ was used as an electrolyte, and a mixed solution in which ethylene carbonate and diethyl carbonate, which are aprotic organic solvents, were mixed at a volume ratio of 1: 1 was used. Further, polypropylene (PP) was used as the separator.

Next, the cycle characteristics of the produced half cells 2-A to half cells 2-I were evaluated. In the cycle test, the charging conditions were a current density of 30 mA / g per active material weight, a constant current charge, and a final voltage of 4.8V. The discharge conditions were 30 mA / g, constant current discharge, and final voltage 2.0V. The temperature at which the charge / discharge measurement was performed was 25 ° C., and a cycle test in which constant current charge / discharge was repeated was performed.

FIG. 30 shows the discharge cycle characteristics of the half cells 2-A to 2-I. In FIG. 30, the vertical axis represents voltage (V) and the horizontal axis represents discharge capacity (mAh / g).

As shown in FIG. 30, in the half cell 2-A to the half cell 2-C in which there is no nickel in the active material or the molar ratio of nickel to manganese is less than 0.2, the discharge capacity is more than 150 [mAh / g]. It was confirmed that it was small. Further, it was confirmed that when the molar ratio of nickel to manganese was 0.2 or more, the discharge capacity was larger than 150 [mAh / g]. In particular, when the molar ratio of nickel to manganese was 0.2 or more and 0.5 or less, the discharge capacity was 230 [mAh / g] or more.

Therefore, it was confirmed that the use of the lithium manganese composite oxide as the active material can prevent the battery voltage and the discharge capacity from decreasing. In addition, in the lithium manganese composite oxide, the molar ratio of manganese to metal atoms is such that manganese is 1 and metal atoms are 0.2 or more and 1.3 or less, preferably metal atoms are 0.2 or more and 0.5 or less. It has been confirmed that it should be.

10 Lithium 11 Manganese 12 Manganese 13 Manganese 14 Manganese 15 Lithium 16 Lithium 17 Manganese 20 Lithium and Manganese Layer 22 Oxygen Layer 23 Lithium and Manganese Layer 24 Lithium and Manganese Layer 100 Electrode 101 Current Collection Body 102 active material layer 300 storage battery 301 positive electrode can 302 negative electrode can 303 gasket 304 positive electrode 305 positive electrode current collector 306 positive electrode active material layer 307 negative electrode 308 negative electrode current collector 309 negative electrode active material layer 310 separator 500 storage battery 501 positive electrode current collector 502 positive electrode Active Material Layer 503 Positive Electrode 504 Negative Electrode Current Collector 505 Negative Electrode Active Material Layer 506 Negative Electrode 507 Separator 508 Electrolyte 509 Exterior Body 510 Positive Electrode Lead Electrode 511 Negative Electrode Lead Electrode 512 Welding Area 513 Curved Part 514 Sealing Part 6 0 storage battery 601 positive electrode cap 602 battery can 603 positive electrode terminal 604 positive electrode 605 separator 606 negative electrode 607 negative electrode terminal 608 insulating plate 609 insulating plate 611 PTC element 612 safety valve mechanism 900 circuit board 910 label 911 terminal 912 circuit 913 storage battery 914 antenna 915 antenna 916 layer 917 Layer 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 951 Terminal 952 Terminal 981 Film 982 Film 990 Storage battery 991 Outer body 993 Outer body 993 Winding body 994 Negative electrode 995 Positive electrode 996 Separator 997 Lead electrode 998 Lead electrode 1700 Curved surface 1701 Plane 1702 Curve 1703 radius of curvature 1704 center of curvature 1800 center of curvature 1801 film 1802 radius of curvature 1803 film 1804 radius of curvature 000 Power storage device 6001 Terminal pair 6002 Terminal pair 6003 Switching control circuit 6004 Switching circuit 6005 Switching circuit 6006 Transformer control circuit 6007 Transformer circuit 6008 Battery unit 6009 Battery cell 6010 Transistor 6011 Bus 6012 Bus 6013 Transistor 6014 Current control switch 6015 Bus 6016 Bus 6017 Switch Pair 6018 Switch pair 6021 Transistor pair 6022 Transistor 6023 Transistor 6024 Bus 6025 Bus 6031 Transistor pair 6032 Transistor 6033 Transistor 6034 Bus 6035 Bus 6041 Battery control unit 6051 Insulation type DC-DC converter 6052 Switch unit 6053 Transformer unit 7100 Portable display device 7101 Housing 7102 display portion 7103 Operation button 7104 Power storage device 7200 Portable information terminal 7201 Case 7202 Display portion 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output terminal 7207 Icon 7300 Display device 7304 Display portion 7400 Cellular phone 7401 Case 7402 Display portion 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Power storage device 7408 Lead electrode 7409 Current collector 8000 Display device 8001 Housing 8002 Display portion 8003 Speaker portion 8004 Power storage device 8021 Charging device 8022 Cable 8024 Power storage device 8100 Lighting device 8101 Housing 8102 Light source 8103 Power storage device 8104 Ceiling 8105 Side wall 8106 Floor 8107 Window 8200 Indoor unit 8201 Housing 8202 Air outlet 8203 Power storage device 8204 Outdoor 8300 Electric refrigerator-freezer 8301 Housing 8302 Refrigerating room door 8303 Freezing room door 8304 Power storage device 8400 Car 8401 Headlight 8500 Car 9600 Tablet terminal 9625 Switch 9626 Switch 9627 Power switch 9628 Operation switch 9629 Tool 9630 Case 9630a Case 9630b Housing 9631 Display portion 9631a Display portion 9631b Display portion 9632a Region 9632b Region 9633 Solar cell 9634 Charge / discharge control circuit 9635 Power storage unit 9636 DCDC converter 9537 Converter 9638 Operation key 9539 Button 9640 Movable portion

Claims (6)

Having particles having lithium, manganese, oxygen, and nickel;
The particles have a layered rock salt type crystal structure region,
An active material, wherein the crystal region has a stacking fault. The stacking fault according to claim 1,
An active material characterized by being observed using an atomic resolution analytical electron microscope. An active material layer comprising the active material according to claim 1, a conductive additive, and a binder,
And an electrode. A first electrode according to claim 3;
A second electrode;
An electrolyte,
A separator,
The first electrode has a function of becoming one of a positive electrode and a negative electrode,
The second electrode has a function of being the other of a positive electrode and a negative electrode. The battery cell according to claim 4;
A lithium ion secondary battery comprising: a battery control unit. A lithium ion secondary battery according to claim 5;
An electronic device including a display device, operation buttons, an external connection port, a speaker, or a microphone.