Electrode, secondary battery, battery pack, and vehicle

Abstract

Embodiments of the present application relate to an electrode, a secondary battery, a battery pack, and a vehicle. Provided are an electrode excellent in input / output performance, a secondary battery excellent in input / output performance, a battery pack, and a vehicle provided with the battery pack. According to the embodiments, an electrode is provided, which includes an active material-containing layer containing an active material, inorganic solid particles having lithium ion conductivity, and a carbon material. The active material-containing layer exhibits a first peak indicating a maximum logarithmic differential pore volume in a logarithmic differential pore volume distribution curve obtained by a mercury intrusion method. A pore diameter D1 of the first peak is 0.05 μm to 10 μm. A first pore volume corresponding to the first peak is 20% to 50% relative to a total pore volume in the active material-containing layer. A ratio of a second pore volume in a range of 0.005 μm to 0.02 μm relative to the first pore volume is 0.1% to 5%.

Description

Technical Field

[0001] Embodiments of the present invention relate to electrodes, secondary batteries, battery packs, and vehicles. Background Technology

[0002] In recent years, lithium-ion secondary batteries and non-aqueous electrolyte secondary batteries have been developed as high-energy-density batteries. These secondary batteries are expected to be used as power sources for vehicles such as hybrid electric vehicles and electric vehicles, or as power sources for large-scale energy storage. When using secondary batteries as vehicle power sources, in addition to high energy density, rapid charge-discharge performance and long-term reliability are also required.

[0003] Rapid charging and discharging is achieved through the rapid movement of lithium ions and electrons between the positive and negative electrodes, which allow for the insertion and extraction of lithium ions and electrons, via an electrolyte and an external circuit. Such fast-charging batteries offer the advantage of significantly shorter charging times. Furthermore, using such fast-charging batteries as a power source for vehicles can improve the vehicle's power performance and, consequently, effectively recover regenerative energy.

[0004] As a method to improve the input and output performance of secondary batteries, the combination of polymeric solid electrolytes in the electrodes is reported. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide electrodes with excellent input and output performance, secondary batteries and battery packs with excellent input and output performance, and vehicles equipped with such battery packs.

[0006] According to an embodiment, an electrode is provided comprising an active material containing an active material, inorganic solid particles with lithium-ion conductivity, and a carbon material. The active material containing layer exhibits a first peak representing the maximum logarithmic differential pore volume in a logarithmic differential pore volume distribution curve obtained using mercury indentation. The pore size D1 of the first peak is 0.05 μm to 10 μm. The first pore volume corresponding to the first peak is 20% to 50% of the total pore volume in the active material containing layer. The ratio of the second pore volume (ranging from 0.005 μm to 0.02 μm) to the first pore volume is 0.1% to 5%.

[0007] According to another embodiment, a secondary battery is provided, comprising a positive electrode, a negative electrode, and an electrolyte. At least one of the positive and negative electrodes is an electrode as described in the above embodiment.

[0008] According to yet another embodiment, a battery pack is provided which includes the secondary battery of the above embodiment.

[0009] According to yet another embodiment, a vehicle is provided which includes the battery pack of the above embodiment.

[0010] Based on the above configuration, it is possible to provide electrodes with excellent input / output performance, secondary batteries and battery packs with excellent input / output performance, and vehicles equipped with such battery packs. Attached Figure Description

[0011] Figure 1 This is a cross-sectional view that schematically illustrates an example of an electrode in an embodiment.

[0012] Figure 2 This is an enlarged cross-sectional view that schematically illustrates an example of an electrode in an embodiment.

[0013] Figure 3 This is an enlarged cross-sectional view that roughly represents an example of a conventional electrode.

[0014] Figure 4 This is a graph showing the logarithmic differential pore volume distribution of an active material layer containing an electrode of an example embodiment.

[0015] Figure 5 It is Figure 4 The chart is obtained by magnifying part S1 in the chart.

[0016] Figure 6 This is a graph showing the logarithmic differential pore volume distribution of the active material containing layers in other examples of electrodes for implementing the embodiments.

[0017] Figure 7 It is Figure 6 The chart is obtained by magnifying part S2 in the chart.

[0018] Figure 8 This is a cross-sectional view that schematically illustrates an example of a secondary battery implementation.

[0019] Figure 9 It is Figure 8 The cross-sectional view is obtained by magnifying part A of the secondary battery shown.

[0020] Figure 10 This is a partial cutaway perspective view schematically illustrating other examples of secondary batteries in various embodiments.

[0021] Figure 11 It is Figure 10 The cross-sectional view of part B of the secondary battery shown is magnified.

[0022] Figure 12 This is a perspective view that schematically illustrates an example of a battery pack embodiment.

[0023] Figure 13 This is an exploded perspective view that schematically illustrates an example of a battery pack embodiment.

[0024] Figure 14 It means Figure 13 The diagram shows a block diagram of an example of the circuitry for the battery pack.

[0025] Figure 15 This is a partial perspective view that schematically represents an example of a vehicle according to an embodiment.

[0026] Figure 16 This is a diagram that schematically illustrates an example of a control system for the electrical system in a vehicle according to an embodiment.

[0027] Symbol Explanation

[0028] 1…Electrode assembly, 2…Outer packaging component, 3…Negative electrode, 3a…Negative electrode current collector, 3b…Negative electrode active material layer, 3c…Negative electrode current collector tab, 4…Separator, 5…Positive electrode, 5a…Positive electrode current collector, 5b…Positive electrode active material layer, 5c…Positive electrode current collector tab, 6…Negative terminal, 7…Positive terminal, 10…Electrode, 10a…Current collector, 10b…Active material layer, 11…Active material particles, 12…Inorganic solid particles, 12A…Inorganic solid secondary particles, 1 3…Carbon material, 21…Busbar, 22…Positive side lead, 22a…Other end, 23…Negative side lead, 23a…Other end, 24…Adhesive tape, 31…Container, 32…Lid, 33…Protective sheet, 34…Printed wiring board, 35…Wiring, 40…Vehicle body, 41…Vehicle power supply, 42…Electrical control device, 43…External terminal, 44…Inverter, 45…Drive motor, 51…Active material particles, 52…Inorganic solid particles, 53…Carbon material 100… Secondary battery, 200… Battery pack, 200a… Battery pack, 200b… Battery pack, 200c… Battery pack, 300… Battery pack, 300a… Battery pack, 300b… Battery pack, 300c… Battery pack, 301a… Battery monitoring device, 301b… Battery monitoring device, 301c… Battery monitoring device, 342… Positive side connector, 343… Negative side connector, 345… Thermistor, 346… Protection circuit, 342a… Wiring, 343a…wiring, 350…external terminal for power supply, 352…positive terminal, 353…negative terminal, 348a…positive side wiring, 348b…negative side wiring, 400…vehicle, 411…battery management device, 412…communication bus, 413…positive terminal, 414…negative terminal, 415…switching device, 416…current detection unit, 417…negative input terminal, 418…positive input terminal, L1…connecting wire, L2…connecting wire, W…drive wheel. Detailed Implementation

[0029] One method to improve the input and output performance of electrodes is to mix inorganic solid particles with lithium-ion conductivity, such as solid electrolyte particles, into the active material containing layer. Solid electrolyte particles exhibit superior lithium-ion conductivity compared to the active material. By incorporating solid electrolyte particles, the lithium-ion conduction resistance within the active material containing layer can be reduced. A higher specific surface area of ​​the solid electrolyte particles makes it easier to exhibit the effect of reducing lithium-ion conduction resistance. On the other hand, if the solid electrolyte particles are miniaturized to increase the specific surface area, the solid electrolyte becomes prone to aggregation and becomes difficult to disperse uniformly within the active material containing layer.

[0030] The embodiments will now be described with reference to the accompanying drawings. It should be noted that common components in the embodiments are labeled with the same symbols, and repeated descriptions are omitted. Furthermore, the figures are schematic diagrams to aid in the explanation and understanding of the embodiments; their shapes, dimensions, proportions, etc., may differ from actual devices. Appropriate design modifications can be made with reference to the following description and well-known techniques.

[0031] [First Implementation]

[0032] According to a first embodiment, an electrode is provided. This electrode includes an active material containing an active material, inorganic solid particles with lithium-ion conductivity, and a carbon material. The logarithmic differential pore volume distribution curve of the active material containing layer obtained by mercury indentation includes a first peak representing the maximum logarithmic differential pore volume. The pore size D1 corresponding to the peak position of the first peak is in the range of 0.05 μm to 10 μm. The proportion of the first pore volume corresponding to the first peak in the total pore volume of the active material containing layer represented by the logarithmic differential pore volume distribution curve is 20% to 50%. The ratio of the second pore volume in the range of 0.005 μm to 0.02 μm to the first pore volume is 0.1% to 5%.

[0033] The electrodes involved can be, for example, battery electrodes. Batteries using these electrodes can be, for example, secondary batteries such as lithium-ion batteries. The term "secondary battery" here includes non-aqueous electrolyte secondary batteries containing a non-aqueous electrolyte. As a specific example, the electrode can be a non-aqueous electrolyte battery electrode on which an active material layer (electrode layer) is formed on a foil-shaped current collector (current collector foil). The electrode can be, for example, included in the battery as a positive electrode and / or a negative electrode.

[0034] The active material containing layer comprises an active material, inorganic solid particles with lithium-ion conductivity, and carbon material as a conductive agent. In addition to the active material, inorganic solid particles, and carbon material, the active material containing layer may further comprise, for example, other conductive agents and binders.

[0035] The electrode of this embodiment contains inorganic solid particles with lithium-ion conductivity, resulting in a low lithium-ion conductivity resistance in the active material containing layer. Furthermore, the inclusion of carbon material reduces the increase in electronic conductivity resistance caused by the inorganic solid particles. Moreover, in an active material containing layer where the pore size D1 of the first peak is in the range of 0.05 μm to 10 μm, the volume of the first pore of this peak accounts for 20% to 50% (0.2 to 0.5) of the total pore volume of the active material containing layer, and the ratio of the total pore volume of pores with a pore size of 0.005 μm to 0.02 μm to the volume of the first pore is 0.1% to 5% (0.001 to 0.05). Therefore, the lithium-ion conductivity resistance can be uniformly reduced throughout the active material containing layer. Thus, using the electrode of this embodiment improves the input / output performance of the secondary battery.

[0036] The electrode may further include a current collector. An active material containing layer may be disposed, for example, on at least one main surface of the current collector. The active material containing layer may be disposed on one main surface of the current collector. Alternatively, the active material containing layer may also be disposed on both main surfaces of the current collector, for example, on both sides of the back surface of a foil-shaped current collector.

[0037] In a current collector, there may be a portion on its surface that does not contain an active material layer. This portion can function as a current collector tab.

[0038] Specific examples of electrodes for the implementation method are shown below. Figure 1 middle. Figure 1 This is a cross-sectional view schematically illustrating an example of an electrode in an embodiment. Figure 1 In the example shown, the arrangement of the electrode that serves as the positive electrode of the battery is explained. Figure 1 This is a schematic cross-sectional view showing the section that intersects with the main surface of the positive electrode 5.

[0039] Figure 1 The positive electrode 5 shown includes a positive current collector 5a and a positive active material containing layer 5b disposed on the positive current collector 5a. The positive current collector 5a includes a portion without the positive active material containing layer 5b, namely the positive current collector tab 5c. In the illustrated example, the positive active material containing layer 5b is supported on both the front and back surfaces of the positive current collector 5a. The positive electrode 5 may also be an electrode with the positive active material containing layer 5b supported only on one side of the positive current collector 5a.

[0040] use Figure 2 The electrodes involved are described in more detail. Figure 2 This is an enlarged cross-sectional view schematically illustrating an example of an electrode in an embodiment. Figure 2 In the example shown, with Figure 1Similarly, the scheme for the positive electrode will be explained. Furthermore, Figure 2 and Figure 1 Similarly, this is a schematic cross-sectional view showing a portion of the section intersecting the main surface of the positive electrode 5. However, with Figure 1 The difference lies in Figure 2 The example shown is one in which the active material is supported on only one side of the current collector and contains a layer.

[0041] Figure 2 The positive electrode 5 shown includes a positive current collector 5a and a positive active material containing layer 5b disposed on the positive current collector 5a. In the illustrated example, the positive active material containing layer 5b is supported on the main surface of one side of the positive current collector 5a. The positive active material containing layer 5b contains active material particles 51, inorganic solid particles 52, and particulate carbon material 53. Figure 2 As illustrated, the inorganic solid particles 52 are not aggregated in the positive electrode active material containing layer 5b, but are dispersed as primary particles. By uniformly dispersing the fine inorganic solid particles 52 as primary particles within the positive electrode active material containing layer 5b, their relatively large surface area can be effectively utilized to promote lithium-ion conduction. Therefore, the electrode of this embodiment exhibits excellent input / output performance.

[0042] For comparison, Figure 3 An example of a conventional electrode is shown. Figure 3 This is an enlarged cross-sectional view that roughly represents an example of a conventional electrode. Figure 3 It is a schematic cross-sectional view showing a portion of the section intersecting the main surface of the electrode. Figure 3 The conventional electrode 10 shown includes a current collector 10a and an active material containing layer 10b disposed on the current collector 10a. In the illustrated example, the active material containing layer 10b is supported on the main surface of one side of the current collector 10a. The active material containing layer 10b contains active material particles 11, inorganic solid particles 12, and particulate carbon material 13. The inorganic solid particles 12 are contained within the active material containing layer 10b as aggregates of inorganic solid secondary particles 12A. The surfaces of the inorganic solid particles 12 facing inward toward the inorganic solid secondary particles 12A are not effectively utilized; however, even with the addition of fine inorganic solid particles 12, the same level of effect as with the addition of large-particle inorganic solid particles can be obtained.

[0043] A specific example is shown of the logarithmic differential pore volume distribution curve obtained by mercury indentation method for the active material containing the electrode of the embodiment. Figure 4 and Figure 6 This is a graph showing the logarithmic differential pore volume distribution of the active material containing the layer in one example of the electrode of the embodiment and other examples. Figure 5 and Figure 7 It is Figure 4 S1 section and Figure 6 The charts are obtained by magnifying the S2 part in the chart.

[0044] Figure 4 and Figure 6 The logarithmic differential pore volume distribution curves shown all have peaks located at pore diameters D1 within the range of 0.05 μm to 10 μm (horizontal axis), including the first peak P1 representing the maximum logarithmic differential pore volume (vertical axis). The cumulative pore volume at the first peak P1, corresponding to the first pore volume, accounts for 20% to 50% of the total pore volume of the active material containing layer obtained by mercury intrusion method shown in the chart. It should be noted that the cumulative pore volume for a certain range of pore diameters (horizontal axis) corresponds to the area under the logarithmic differential pore volume distribution curve in the corresponding width of the chart within that range, i.e., the value obtained by integrating the logarithmic differential pore volume distribution (vertical axis) within that range.

[0045] Furthermore, the first pore volume does not correspond to the accumulated pore volume in the range of 0.05 μm to 10 μm, but rather to the accumulated pore volume in the range between the pore diameter (horizontal axis) and the minimum value of a certain logarithmic differential pore volume (vertical axis) before and after the peak of the first peak P1. For example, Figure 4 In the example shown, the cumulative pore volume in the range from 0.07 μm to 0.4 μm corresponds to the first pore volume. Figure 6 In the example shown, the cumulative pore volume in the range from 0.09 μm to 0.4 μm corresponds to the first pore volume.

[0046] In the illustrated example, the logarithmic differential pore volume distribution curve includes a second peak P2 in the range (horizontal axis) of pore diameter from 0.005 μm to 0.02 μm. The electrode of the embodiment also includes a scheme in which the second peak P2 is not present in the aforementioned range of the logarithmic differential pore volume distribution curve of the active material containing layer. For example, a shoulder of the first peak may be included in the range of pore diameter from 0.005 μm to 0.02 μm.

[0047] The cumulative pore volume (second pore volume) in the range of pore diameter of 0.005 μm to 0.02 μm is taken as a value of 0.1% to 5% relative to the first pore volume of the first peak P1 (0.001 ≤ second pore volume / first pore volume ≤ 0.05).

[0048] Peak P1 primarily reflects the micropores formed between active material particles within the active material containing layer. The logarithmic differential micropore volume distribution curve shows micropores with diameters ranging from 0.005 μm to 0.02 μm, mainly reflecting micropores formed between inorganic solid particles that have not undergone excessive condensation.

[0049] like Figure 4 and Figure 5 as well as Figure 6 and Figure 7 As illustrated in the examples, in an active material containing a layer where the logarithmic differential pore volume distribution curve obtained using the mercury indentation method contains the most intense peak (first peak P1) within the aforementioned range, the pore volume of that peak (first pore volume), and the pore volume with a pore diameter of 0.005 μm to 0.02 μm (second pore volume), the inorganic solid particles are uniformly dispersed within the layer in a non-agglomerated state. Therefore, electrodes possessing such active material containing layers can exhibit excellent input / output performance. Furthermore, due to the minimal non-uniformity in the diffusion rate of lithium ions within the active material containing layer, the entire active material containing layer can participate equally in the charge / discharge reaction, minimizing the likelihood of partial degradation.

[0050] The total pore volume of the active material containing layer obtained by mercury infiltration is preferably 0.05 mL / g to 0.10 mL / g. Active material containing layers with a total pore volume within this range have high energy density and can maintain sufficient electrolytes. More preferably, the total pore volume is 0.06 mL / g to 0.08 mL / g.

[0051] The following is a detailed description of the electrodes involved.

[0052] The active substance containing layer can contain only one compound as the active substance, or it can contain two or more compounds in combination.

[0053] The active material containing layer contains the active material, for example, in the form of particles. The active material is preferably contained in the active material containing layer in the form of primary particles. Regarding solid electrolyte particles, active material in the form of primary particles can be dispersed better than active material that aggregates to form secondary particles. The active material particles preferably have an average primary particle size of 1 μm to 20 μm.

[0054] Inorganic solid particles are incorporated to improve the lithium-ion conductivity of the active material containing layer. Preferably, the inorganic solid particles comprise at least one compound selected from a first metal oxide containing at least one element selected from Ti, Ge, Sr, Zr, Sn, Al, Sc, Y, Ba, P, and Ca; a lanthanide oxide; and a first sulfide containing at least one element selected from Li, Ge, P, Si, Sn, Al, Ga, B, and In. Lanthanide oxides are oxides containing lanthanides such as La, Ce, Pr, and Nd. It should be noted that the first metal oxide may further contain lanthanides such as La.

[0055] Examples of inorganic solid particles include oxide-based solid electrolytes and sulfide-based solid electrolytes. As an oxide-based solid electrolyte, a lithium phosphate solid electrolyte with a NASICON-type structure and the general formula LiMe2(PO4)3 is preferred. In the above general formula, Me is preferably selected from at least one element chosen from titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), and aluminum (Al). More preferably, element Me includes any one of Ge, Zr, and Ti, and Al.

[0056] As a specific example of a lithium phosphate solid electrolyte with a NASICON-type structure, LATP (Li 1+d+ e Al d Ti 2-d Si e P 3-e O 12 ;0 <d≤2、0≤e<3)、Li 1+f+e Al f Ge 2-f Si e P 3-e O 12 ; 0≤f≤2、0≤e<3、Li 1+ f Al f Zr 2-f (PO4)3; 0≤f≤2 and Li 1+2g Ca g Zr 1-g (PO4)3; 0 ≤ g < 1. Li 1+2g Ca g Zr 1-g (PO4)3 is preferred as an inorganic solid electrolyte particle due to its high water resistance, reducibility, and low cost.

[0057] In addition to the aforementioned lithium phosphate solid electrolyte, other oxide-based solid electrolytes, such as those based on Li... h POi N j This refers to amorphous LIPON compounds (e.g., Li) where 2.6 ≤ h ≤ 3.5, 1.9 ≤ i ≤ 3.8, and 0.1 ≤ j ≤ 1.3. 2.9 PO 3.3 N 0.46 ); Garnet-type structure with Li 5+k X k La 3-k Mα2O 12 This indicates that X is selected from one or more of Ca, Sr, and Ba, and Mα is selected from one or more of Nb and Ta, with 0 ≤ k ≤ 0.5; Li3Mβ 2-k L2O 12 This indicates that Mβ is a compound selected from Ta and Nb, and L may contain Zr, with 0 ≤ k ≤ 0.5; Li 7-3k Al k La3Zr3O 12 Represents compounds in which 0 ≤ k ≤ 0.5; and compounds in which Li 5+f La3Mγ 2-f Zr f O 12 This indicates that Mγ is an LLZ compound selected from Nb and Ta, and 0 ≤ f ≤ 2 (e.g., Li7La3Zr2O). 12 ).

[0058] In addition, sodium-containing solid electrolytes can also be used as solid electrolytes. Sodium ions in sodium-containing solid electrolytes exhibit excellent ionic conductivity. Examples of sodium-containing solid electrolytes include β-alumina, sodium phosphide sulfides, and sodium phosphide oxides. Sodium-containing solid electrolytes are preferably in the form of glass-ceramics.

[0059] The inorganic solid particles are preferably those with a density of 1×10⁻⁶ at 25°C. -5 Solid electrolytes with lithium-ion conductivity of S / cm or higher. Lithium-ion conductivity can be determined, for example, by alternating current impedance analysis. Specifically, firstly, inorganic solid particles are shaped using a tablet former to obtain a pressed powder. Gold (Au) is then vapor-deposited on both sides of the pressed powder to obtain a test sample. The alternating current impedance of the test sample is measured using an impedance measuring device. For example, a Solartron 1260 frequency response analyzer is used as the measuring device. During the measurement, the measurement frequency is set to 5 Hz to 32 MHz, the measurement temperature is set to 25 °C, and the measurement is performed under an argon atmosphere.

[0060] Based on the measured AC impedance, a complex impedance plot is constructed. A complex impedance plot is a graph where the horizontal axis represents the real components and the vertical axis represents the imaginary components. The ionic conductivity σ of the inorganic solid particles is calculated using the following formula. LiIt should be noted that in the following formula, Z... Li S is the resistance value calculated from the diameter of the arc in the complex impedance diagram, where S is the area and d is the thickness.

[0061] σ Li =(1 / Z) Li )×(d / S)

[0062] The solid electrolyte is preferably a Lewis acid. Such a solid electrolyte readily carries a positive charge, thus enabling it to capture anions in the electrolyte. Consequently, lithium ions, acting as cations within the active material containing the layer, become more mobile. Examples of such solid electrolytes include the aforementioned Li... 1+2g Ca g Zr 1-g (PO4)3, LATP.

[0063] The shape of inorganic solid particles is not particularly limited, but can be set as spherical, elliptical, flat or fibrous, etc.

[0064] The average primary particle size of the inorganic solid particles is preferably below 2 μm. If the average primary particle size of the inorganic solid particles is small, there is a tendency for the internal resistance of the battery to be low.

[0065] The average primary particle size of the inorganic solid particles is preferably 0.2 μm or larger. If the average primary particle size of the inorganic solid particles is large, there is a tendency for particle aggregation to be suppressed.

[0066] The electrodes involved incorporate carbon materials as conductive agents. The conductive agent is designed to improve current collection performance and suppress contact resistance between the active material and the current collector. For the carbon material, at least particulate carbon materials are preferred. Examples of such particulate conductive agents include carbon black such as acetylene black and graphite. One of these can be used as a conductive agent, or a combination of two or more can be used. Other conductive agents include fibrous carbon materials, planar or sheet-like carbon materials, etc. Examples of fibrous carbon materials include vapor-grown carbon fiber (VGCF), carbon nanofibers, and carbon nanotubes. Examples of planar or sheet-like carbon materials include graphene. Furthermore, in addition to including conductive agents, the surface of the active material particles can be further coated with carbon or electronically conductive inorganic materials.

[0067] In the active material containing layer, the amount of carbon material relative to 100 parts by mass of active material is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass. A higher amount of carbon material can improve the electronic conductivity of the active material containing layer. On the other hand, an excessive amount of carbon material may reduce the energy density.

[0068] Adhesives are used to fill the gaps between dispersed active materials and to bond the active materials to the current collector. Examples of adhesives include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene-butadiene rubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these can be used as an adhesive, or a combination of two or more can be used.

[0069] In the active material containing layer, the amount of binder relative to 100 parts by mass of active material is preferably 0 to 10 parts by mass, more preferably 1 to 5 parts by mass. If the amount of binder is large, the adhesion between the active material containing layer and the current collector becomes sufficient, and excellent cycling performance can be expected. On the other hand, if the amount of binder is excessive, the energy density may decrease.

[0070] For the current collector, a material that is electrochemically stable at the potential for lithium (Li) insertion and extraction into the active material can be used. For example, the current collector is preferably made of copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. The thickness of the current collector is preferably 5 μm to 20 μm. A current collector with such a thickness achieves a balance between electrode strength and lightweight.

[0071] The electrode in this embodiment can be used as either a positive or negative electrode. Preferably, the electrode in this embodiment is used as a positive electrode.

[0072] Next, the schemes of the electrode in the first embodiment as a negative electrode and as a positive electrode will be described in detail.

[0073] (positive electrode)

[0074] The positive electrode may include a positive current collector and a positive active material containing layer. The positive active material containing layer may be formed on one or both sides of the positive current collector. The positive active material containing layer may include positive active material, inorganic solid particles, carbon materials, and optionally other conductive agents and binders. The positive current collector and the positive active material containing layer may be the current collector and active material containing layer described above, respectively.

[0075] The positive electrode active material may, for example, include a lithium-containing transition metal composite oxide. The lithium-containing transition metal composite oxide preferably comprises at least one transition metal selected from the group consisting of nickel, cobalt and manganese. Preferably, in addition to the aforementioned transition metals, the lithium-containing transition metal composite oxide further comprises at least one element selected from titanium and aluminum. The lithium-containing transition metal composite oxide can be represented by Li 1-v Ni 1-a-b Co a Mn b A c vO2, wherein A is at least one element selected from the group consisting of Al, Ti, Zr, Nb, Mg, Cr, V, Fe, Ta, Mo, Zn, Ca, Sn, Si and P, v is from 0 to 1, a is from 0 to 1, b is from 0 to 1, the sum of a and b is 1 or less, and c is from 0 to 1.

[0076] Examples of the lithium-containing transition metal composite oxide include lithium manganese composite oxides (such as Li x xMn2O4 or Li x xMnO2; 0<x≤1), lithium nickel composite oxides (such as Li x xNiO2; 0<x≤1), lithium cobalt composite oxides (such as Li x xCoO2; 0<x≤1), lithium nickel cobalt composite oxides (such as Li x xNi 1-y yCo y O2; 0<x≤1, 0<y<1), lithium manganese cobalt composite oxides (such as Li x xMn y yCo 1-y O2; 0<x≤1, 0<y<1), lithium manganese nickel composite oxides with spinel structure (such as Li x xMn 2-w wNi w O4; 0<x≤1, 0<w<2), lithium phosphorus oxides with olivine structure (such as Li x xFePO4; 0<x≤1, Li x xFe 1-y yMn y PO4; 0<x≤1, 0<y<1, Li x xCoPO4; 0<x≤1) and lithium nickel cobalt manganese composite oxides (Li x xNi 1-y-z yCo y zMn z O2; 0<x≤1, 0<y<1, 0<z<1, y+z<1).

[0077] Alternatively, the positive electrode active material may comprise other oxides and sulfides. Examples of oxides and sulfides include compounds capable of intercalating and deintercalating Li or Li ions. Examples of other oxides include manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, and vanadium oxides (e.g., V2O5). Examples of other sulfides include ferric sulfate (Fe2(SO4)3).

[0078] The specific surface area of ​​the positive electrode active material is preferably 0.1 m². 2 / g~10m 2 / g. It has 0.1m 2 Positive electrode active materials with a specific surface area of ​​over / g can adequately ensure the insertion / extraction sites of Li ions. With a specific surface area of ​​10m... 2 Positive electrode active materials with a specific surface area of ​​less than 1 g are easy to process in industrial production and can ensure good charge-discharge cycle performance.

[0079] The positive current collector is preferably aluminum foil, or aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu, and Si. The purity of the aluminum foil is preferably 99% by mass or higher. The content of transition metals such as iron, copper, nickel, and chromium in the aluminum foil or aluminum alloy foil is preferably less than 1% by mass.

[0080] Furthermore, the positive current collector can be included in the portion of its surface where no positive active material layer is formed. This portion can function as a positive current collector tab.

[0081] The density of the positive electrode active material containing the layer (excluding the current collector) is preferably 3.0 g / cm³. 3 ~3.6g / cm 3 More preferably 3.2 g / cm³ 3 ~3.5g / cm 3 .

[0082] (negative electrode)

[0083] The negative electrode may include a negative current collector and a negative active material containing layer. The negative active material containing layer may include a negative active material, inorganic solid particles, carbon materials, and optionally other conductive agents and binders. The negative current collector and the negative active material containing layer may be the current collector and active material containing layer described above, respectively.

[0084] Examples of negative electrode active materials include lithium titanate (e.g., Lithium titanate with a spinel structure). 4+m Ti5O 12Lithium titanate (0≤m≤3), titanium dioxide (TiO2), anatase titanium dioxide, rutile titanium dioxide, niobium pentoxide (Nb2O5), manganese barite titanium composite oxides, and lithium titanium oxides with orthorhombic manganese oxide structure (e.g., Li) 2+m Ti3O7, orthorhombic titanium-containing composite oxides, and monoclinic niobium-titanium composite oxides.

[0085] Examples of orthorhombic titanium-containing composite oxides include Li 2+n M1 2-r Ti 6-s M2 t O 14+σ The compound referred to herein. M1 is at least one selected from Sr, Ba, Ca, Mg, Na, Cs, Rb, and K. M2 is at least one selected from Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. The subscripts in the composition formula are 0 ≤ n ≤ 6, 0 ≤ r < 2, 0 ≤ s < 6, 0 ≤ t < 6, and -0.5 ≤ σ ≤ 0.5. As a specific example of an orthorhombic titanium-containing composite oxide, Li can be cited. 2+ n Na2Ti6O 14 (0≤n≤6).

[0086] As examples of the aforementioned monoclinic niobium-titanium composite oxides, Li can be cited. u Ti 1-g M3 g Nb 2-r M4 r O 7+δ The compounds referred to herein. M3 is selected from at least one of Zr, Si, and Sn. M4 is selected from at least one of V, Ta, and Bi. The subscripts in the composition formula are 0 ≤ u ≤ 5, 0 ≤ g < 1, 0 ≤ r < 2, and -0.3 ≤ δ ≤ 0.3. As a specific example of a monoclinic niobium-titanium composite oxide, Li can be cited. u Nb2TiO7 (0≤u≤5).

[0087] Other examples of monoclinic niobium-titanium composite oxides include Li u Ti 1-g M5 g+r Nb 2-r O 7-δ The compound represented is M5, which is selected from at least one of Mg, Fe, Ni, Co, W, Ta, and Mo. The subscripts in the composition formula are 0 ≤ u ≤ 5, 0 ≤ g < 1, 0 ≤ r < 2, and -0.3 ≤ δ ≤ 0.3.

[0088] The negative current collector is preferably made of copper, nickel, stainless steel or aluminum, or an aluminum alloy containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu and Si.

[0089] Furthermore, the negative current collector can be contained in the portion of its surface where no negative active material layer is formed. This portion can function as a negative current collector tab.

[0090] The density of the negative electrode active material containing the layer (excluding the current collector) is preferably 1.8 g / cm³. 3 ~2.8g / cm 3 The density of the negative electrode active material containing the layer within this range indicates excellent energy density and electrolyte retention of the negative electrode. More preferably, the density of the negative electrode active material containing the layer is 2.1 g / cm³. 3 ~2.6g / cm 3 .

[0091] <Manufacturing Method>

[0092] Next, the method for manufacturing the electrode according to the embodiment will be described.

[0093] First, inorganic solid particles are dispersed in a solvent and stirred to prepare a first slurry. For example, N-methyl-2-pyrrolidone is used as the solvent. The solid content in the dispersion is adjusted to 10%–70%. A bead mill is used as the mixer. A specific bead mill mixer is, for example, the StarMill LME4 bead mill manufactured by Ashizawa Finetech. The stirring process is carried out for 1 minute to 1 hour under conditions of bead diameter Φ0.1 mm–5 mm, bead filling rate 40%–90%, and stirring speed 300 rpm–2000 rpm. More preferably, the stirring process is carried out at a stirring speed of 700 rpm–1500 rpm.

[0094] Next, the first slurry, active material, granular carbon, optional binder, and other carbon materials are mixed and stirred to prepare the second slurry. Here, a two-stage stirring process is performed, consisting of stirring using a planetary mixer followed by further stirring using a bead mill. In the first stage of stirring using the planetary mixer, the stirring speed is set, for example, to 30 rpm to 6000 rpm, and the stirring time is set to 10 minutes to 2 hours. The second stage of stirring using the bead mill is performed under the conditions of bead diameter Φ0.5 mm to 3 mm, bead filling rate 40% to 90%, and stirring speed 300 rpm to 2000 rpm for 3 minutes to 1 hour.

[0095] A second slurry is coated onto one or both sides of the current collector, and the coating is dried, for example, at a temperature of 100°C to 120°C, to obtain a laminate of the active material containing layer and the current collector. An electrode is obtained by pressing this laminate. In this method, the aggregation of inorganic solid particles is suppressed, and the inorganic solid particles are sufficiently dispersed among the active materials. Therefore, since inorganic solid particles with a large specific surface area can be dispersed in the active material containing layer, an electrode exhibiting excellent output performance can be obtained.

[0096] <Determination Method>

[0097] The measurement methods for electrodes are explained below. Specifically, the method for obtaining the logarithmic differential pore volume distribution curve of the active material containing layer by mercury indentation and the method for confirming the active material contained in the electrode are explained.

[0098] When measuring the electrodes assembled in the battery, the electrodes are removed from the battery by the following steps.

[0099] First, the battery is brought to a discharged state. Here, "discharged state" refers to the state where the battery's charge rate reaches 0%. The discharged battery is placed in a glove box with an inert atmosphere, such as a glove box filled with argon. Next, the electrode to be tested is removed from the battery inside the glove box. Specifically, inside the glove box, to be on the safe side and to avoid short-circuiting the positive and negative terminals, the outer packaging of the battery is cut and opened. From this, for example, if the electrode used in the positive terminal is being used as a test sample, the electrode connected to the positive terminal is cut off. Alternatively, if the electrode used in the negative terminal is being used as a test sample, the electrode connected to the negative terminal is cut off. The removed electrode is then immersed in, for example, diethyl carbonate solvent for 3 minutes, and then dried inside the glove box under an inert gas atmosphere.

[0100] (Method for obtaining the logarithmic differential pore volume distribution curve)

[0101] The logarithmic differential pore volume distribution curve of the active material containing the layer using the mercury indentation method can be obtained, for example, by the following method.

[0102] The electrode, which serves as the test sample, is cut to obtain multiple test pieces. The size of the test piece is, for example, set to a rectangle with a short side of 1.25 cm and a long side of 2.5 cm. It should be noted that the test piece is cut at the center portion containing an imaginary line parallel to the short side of the electrode. In this case, if the electrode is a wound type, the portion obtained by further dividing the imaginary line parallel to the long side equally according to the number of test pieces is cut. Furthermore, if the electrode is a stacked type, the test piece is obtained by further cutting the center portion of the imaginary line parallel to the long side of each stacked electrode. If the number of electrode pieces is less than the intended number of test pieces, multiple pieces can be cut from a single electrode.

[0103] Next, multiple test pieces are placed in the measuring unit of the measuring device, allowing mercury to penetrate into the fine pores of the test pieces. The number of test pieces is set to, for example, 16 to 32. As the measuring unit, a 5cc unit with a stem volume of 0.4cc is used, for example. As the measuring device, a Shimadzu AutoPore 9520 (Autopore 9520 model manufactured by Shimadzu corporation) is used, for example. During the measurement, the initial pressure is set to, for example, 7 kPa, and the final pressure is set to 414 MPa. Measurements are performed every 1.1 kPa from the initial pressure. n The pressure is measured at times the rated pressure. n is a positive integer. That is, for example, 7 kPa, 7.7 kPa, 8.47 kPa, 9.317 kPa, ..., 7 × 1.1 kPa. n The test was conducted at kPa until the pressure reached 414 MPa. 7 kPa is equivalent to 1.0 psia (pounds per square inch absolute), which corresponds to a pore diameter of approximately 180 μm. Furthermore, 414 MPa is equivalent to approximately 6 psia, corresponding to a pore diameter of approximately 0.003 μm. The mercury contact angle was set to 130 degrees, and the mercury surface tension was set to 485 dynes / cm. By processing the obtained data, the logarithmic differential pore volume distribution curve of the active material containing the layer, as well as the total pore volume and the pore volume for each range of pore diameters, can be obtained.

[0104] (Methods for identifying active substances and inorganic solid particles)

[0105] By combining elemental analysis using a scanning electron microscope (SEM-EDX) equipped with an energy-dispersive X-ray spectrometry (SEM-EDX) device, X-ray diffraction (XRD) measurements, and inductively coupled plasma (ICP) luminescence spectrometry, the composition of the active material and inorganic solid particles contained in the active material-containing layer of an electrode can be confirmed. SEM-EDX analysis reveals the shape and composition (elements from B to U in the periodic table) of the components within the active material-containing layer. ICP measurements allow for the quantification of the elements in the active material-containing layer. Furthermore, XRD measurements confirm the crystal structure of the materials contained in the active material-containing layer.

[0106] The cross-section of the electrode, obtained through the procedures described above, is cut out using Ar ion milling. The cut cross-section is then observed using SEM. Sample sampling is also conducted in an inert atmosphere such as argon or nitrogen, without contact with the atmosphere. Several particles are selected from the 3000x SEM image. At this point, the selection is made in a way that maximizes the particle size distribution of the selected particles.

[0107] Next, elemental analysis is performed on each selected particle using EDX. This allows us to identify the types and amounts of elements other than Li contained in each selected particle.

[0108] Regarding Li, information about the Li content in the entire layer containing the active material can be obtained by ICP-luminescence spectrometry. ICP-luminescence spectrometry is performed according to the following steps.

[0109] Prepare a powder sample from the dried electrode as follows: Peel off the active material layer from the current collector and crush it using a mortar. Dissolve the crushed sample in an acid to prepare a liquid sample. Hydrochloric acid, nitric acid, sulfuric acid, hydrogen fluoride, etc., can be used as the acid. By performing ICP-based spectroscopy on this liquid sample, the concentrations of the active material and elements contained in the inorganic solid particles can be determined.

[0110] The crystal structure of the compound contained in each selected particle in SEM can be identified by XRD determination. This specific crystal structure allows for the differentiation of the composite oxide from the electrode active material. XRD determination is performed using CuKα rays as the radiation source within a measurement range of 2θ = 5° to 90°. This determination yields the X-ray diffraction pattern of the compound contained in the selected particle.

[0111] The Rigaku SmartLab was used as the XRD apparatus. The measurement conditions were set as follows:

[0112] X-ray source: Cu target

[0113] Output power: 45kV, 200mA

[0114] Slatter slit: both incident and received light angles are 5°.

[0115] Step width (2θ): 0.02deg

[0116] Scanning speed: 20 deg / minute

[0117] Semiconductor detector: D / teX Ultra 250

[0118] Sample plate holder: Flat glass sample plate holder (0.5mm thick)

[0119] Measurement range: 5°≤2θ≤90°.

[0120] When using other apparatus, measurements are performed using standard Si powder for powder X-ray diffraction. The conditions under which the same peak intensity, half-width, and diffraction angle as those obtained by the apparatus described above are found, and the samples are measured under these conditions.

[0121] The XRD measurement conditions were set to obtain XRD patterns applicable to Rietveld analysis. Specifically, to collect data for Rietveld analysis, the step width was set to 1 / 3 to 1 / 5 of the minimum half-width of the diffraction peak, and the measurement time or X-ray intensity was appropriately adjusted so that the intensity at the position of the most intense reflection peak was 5000 cps or more.

[0122] The XRD pattern obtained as described above is analyzed using the Rietveld method. In the Rietveld method, the diffraction pattern is calculated from a pre-estimated crystal structure model. This crystal structure model is estimated based on the analysis results using EDX and ICP. By fitting all the calculated and measured values, parameters related to the crystal structure (lattice constant, atomic coordinates, occupancy, etc.) can be precisely analyzed.

[0123] XRD measurements can be performed by directly attaching the electrode sample to the glass holder of a wide-angle X-ray diffractometer. In this case, the XRD spectrum is pre-measured according to the type of metal foil used for the electrode current collector to determine the location of the peak originating from the current collector. Furthermore, the presence or absence of peaks from agents such as conductive agents or binders is also pre-determined. If the peaks of the current collector overlap with those of the active material, it is preferable to peel the active material containing layer from the current collector before measurement. This is to separate the overlapping peaks when quantitatively measuring peak intensity. Of course, if these factors can be determined beforehand, this step can be omitted.

[0124] (Methods for determining particle size)

[0125] The average primary particle size of active substances and the average primary particle size of inorganic solid particles can be obtained by observation using a transmission electron microscope (TEM).

[0126] For the electrode used as the test sample, a TEM image was taken at a magnification of, for example, 50,000x, to clearly show the primary particles of the active material and inorganic solid particles. Next, for both the active material and inorganic solid particles, primary particles that were clearly visible in their entirety were selected from the TEM images. These primary particles were then approximated as ellipses. In this approximation, the ratio of the major axis to the minor axis of the ellipse was set in a way that minimized the difference between the outline of the primary particle and the outline of the ellipse's circumference. The lengths of the major and minor axes of the ellipse were then measured. The sum of the lengths of the major and minor axes of the ellipse obtained in this manner was set as the particle size of the primary particle. The same operation was performed on 100 randomly selected particles, and their sum was set as the average particle size of the primary particle.

[0127] The electrode of the first embodiment comprises an active material containing an active material, inorganic solid particles with lithium-ion conductivity, and a carbon material. The peak of the logarithmic differential pore volume distribution curve obtained using mercury indentation for the active material containing the active material is located at a pore diameter D1 in the range of 0.05 μm to 10 μm, and includes a first peak representing the maximum logarithmic differential pore volume. The ratio of the first pore volume of the first peak to the total pore volume is 20% to 50%. The ratio of the second pore volume in the range of 0.005 μm to 0.02 μm to the first pore volume is 0.1% to 5%. This electrode exhibits excellent input / output performance.

[0128] [Second Implementation]

[0129] According to a second embodiment, a secondary battery is provided, comprising a positive electrode, a negative electrode, and an electrolyte. At least one of the positive and negative electrodes is an electrode of the first embodiment.

[0130] The secondary battery of the second embodiment may further include a separator disposed between the positive and negative electrodes. The positive electrode, negative electrode, and separator may constitute an electrode assembly. The electrolyte may be retained in the electrode assembly.

[0131] Furthermore, the secondary battery of the second embodiment may further include an outer packaging component that accommodates the electrode assembly and the electrolyte.

[0132] Furthermore, the secondary battery of the second embodiment may further include a positive terminal electrically connected to the positive electrode and a negative terminal electrically connected to the negative electrode.

[0133] The secondary battery in the second embodiment can be, for example, a lithium secondary battery. Furthermore, the secondary battery includes a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte.

[0134] The following describes the positive electrode, negative electrode, electrolyte, separator, outer packaging components, positive terminal, and negative terminal.

[0135] 1) Positive electrode

[0136] The positive electrode can be the same as the electrode in the first embodiment. Alternatively, in a battery that includes the electrode of the first embodiment as the negative electrode, the positive electrode can be a different positive electrode than the electrode of the first embodiment.

[0137] Other positive electrodes may be positive electrodes that do not contain solid electrolyte particles in the active material containing layer (positive electrode active material containing layer). Furthermore, in the logarithmic differential pore volume distribution curves obtained using the mercury indentation method for the active material containing layer of other positive electrodes, the peak position of the most intense peak may be outside the range of 0.05 μm to 10 μm. Alternatively, even if the position of the most intense peak is within the range of 0.05 μm to 10 μm, the proportion of the pore volume corresponding to that peak (first pore volume) may be less than 20% or more than 50% of the total. Alternatively, the ratio of the pore volume in the range of 0.005 μm to 0.2 μm (second pore volume) corresponding to the pore volume of the most intense peak (first pore volume) may be less than 0.1% or more than 5%. Apart from this, the details of other positive electrodes are the same as those of the electrode in the first embodiment.

[0138] Since the description is repeated in the first embodiment, detailed description is omitted.

[0139] 2) Negative electrode

[0140] The negative electrode can be the same as the negative electrode in the first embodiment. Alternatively, in a battery that includes the electrode of the first embodiment as the positive electrode, the negative electrode can be a different negative electrode than the electrode of the first embodiment.

[0141] Other negative electrodes may be negative electrodes that do not contain solid electrolyte particles in the active material containing layer (negative electrode active material containing layer). Furthermore, in the logarithmic differential pore volume distribution curves obtained using the mercury indentation method for the active material containing layer of other negative electrodes, the peak position of the most intense peak may be outside the range of 0.05 μm to 10 μm. Alternatively, even if the position of the most intense peak is within the range of 0.05 μm to 10 μm, the proportion of the pore volume corresponding to that peak (first pore volume) may be less than 20% or more than 50% of the total. Alternatively, the ratio of the pore volume in the range of 0.005 μm to 0.2 μm (second pore volume) corresponding to the pore volume of the most intense peak (first pore volume) may be less than 0.1% or more than 5%. Apart from this, the details of the other negative electrodes are the same as those of the electrode in the first embodiment.

[0142] Since the description is repeated in the first embodiment, detailed description is omitted.

[0143] 3) Electrolytes

[0144] As the electrolyte, for example, a liquid non-aqueous electrolyte or a gel-like non-aqueous electrolyte can be used. A liquid non-aqueous electrolyte is prepared by dissolving an electrolyte salt, which is the solute, in an organic solvent. The concentration of the electrolyte salt is preferably 0.5 mol / L to 2.5 mol / L.

[0145] Examples of electrolyte salts include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluoride phosphate (LiPF6), lithium tetrafluoride borate (LiBF4), lithium hexafluoride arsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2), as well as mixtures thereof. The electrolyte salt is preferably a substance that is difficult to oxidize even at high potentials, with LiPF6 being the most preferred.

[0146] Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate (VC); chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC); cyclic ethers such as tetrahydrofuran (THF), 2-methyl tetrahydrofuran (2MeTHF), and dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL); acetonitrile (AN); and sulfolane (SL). These organic solvents can be used alone or as mixed solvents.

[0147] Gel-like nonaqueous electrolytes are prepared by combining liquid nonaqueous electrolytes with polymeric materials. Examples of polymeric materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

[0148] Alternatively, as a non-aqueous electrolyte, in addition to liquid non-aqueous electrolytes and gel non-aqueous electrolytes, room-temperature molten salts (ionic melts) containing lithium ions, polymeric solid electrolytes, and inorganic solid electrolytes can also be used.

[0149] Room-temperature molten salts (ionic melts) refer to compounds in organic salts containing a combination of organic cations and anions that exist as liquids at room temperature (15°C–25°C). Room-temperature molten salts include those existing as liquids in elemental form, those that become liquids by mixing with electrolyte salts, those that become liquids by dissolving in organic solvents, or mixtures thereof. Generally, the melting point of room-temperature molten salts used in secondary batteries is below 25°C. Furthermore, the organic cations typically possess a quaternary ammonium framework.

[0150] Polymer solid electrolytes are prepared by dissolving electrolyte salts in polymer materials and then solidifying them.

[0151] Inorganic solid electrolytes are solid substances that have Li ion conductivity.

[0152] 4) Diaphragm

[0153] The diaphragm can be formed, for example, from a porous membrane containing polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), cellulose, or polyvinylidene fluoride (PVdF), or from a nonwoven fabric made of synthetic resin. Alternatively, a diaphragm coated with an inorganic or organic compound can also be used. From a safety perspective, porous membranes made of polyethylene or polypropylene are preferred. This is because these porous membranes melt at a certain temperature and can block the current.

[0154] 5) Outer packaging components

[0155] As outer packaging components, containers made of laminated film or metal containers can be used, for example.

[0156] The thickness of the laminate is, for example, 0.5 mm or less, preferably 0.2 mm or less.

[0157] As a laminated film, a multilayer film comprising multiple resin layers and a metal layer sandwiched between these resin layers is used. The resin layers include, for example, polymeric materials such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET). For weight reduction, the metal layer is preferably made of aluminum foil or aluminum alloy foil. The laminated film is sealed using hot-melt bonding and can be shaped into an outer packaging component.

[0158] The thickness of the wall of the metal container is, for example, 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.2 mm or less.

[0159] The metal container is made of materials such as aluminum or aluminum alloys. The aluminum alloy preferably contains elements such as magnesium, zinc, and silicon. When the aluminum alloy contains transition metals such as iron, copper, nickel, and chromium, their content is preferably less than 100 ppm by mass. For batteries with such metal containers, long-term reliability and heat dissipation under high-temperature environments can be significantly improved.

[0160] There are no particular limitations on the shape of the outer packaging component. The outer packaging component can be, for example, flat (thin), square, cylindrical, coin-shaped, button-shaped, sheet-shaped, or stacked. The outer packaging component can be appropriately selected according to the battery size and intended use. For example, the outer packaging component can be used for small batteries mounted in portable electronic devices. Furthermore, the outer packaging component can be used for large batteries mounted in vehicles such as two-wheeled to four-wheeled cars.

[0161] 6) Positive extreme

[0162] The positive terminal can be located in a potential range of 3V to 4.5V relative to the redox potential of lithium (vs. Li / Li). + The positive terminal is formed of a material that is electrically stable and conductive. Examples of materials for the positive terminal include aluminum, or aluminum alloys containing at least one element selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. To reduce the contact resistance with the positive current collector, the positive terminal is preferably formed of the same material as the positive current collector.

[0163] 7) Negative extremes

[0164] The negative electrode can be used in a potential range of 0.8V to 3V relative to the redox potential of lithium (vs. Li / Li). + The negative terminal is formed of a material that is electrically stable and conductive. Specifically, examples of materials for the negative terminal include copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing at least one element selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. Aluminum or an aluminum alloy is preferred as the material for the negative terminal. To reduce the contact resistance with the negative current collector, the negative terminal is preferably formed of the same material as the negative current collector.

[0165] Next, the secondary battery of the second embodiment will be described in more detail with reference to the accompanying drawings.

[0166] Figure 8 This is a cross-sectional view that schematically illustrates an example of a secondary battery according to the second embodiment. Figure 9 It is Figure 8 The cross-sectional view is obtained by magnifying part A of the secondary battery shown.

[0167] Figure 8 and Figure 9 The secondary battery 100 shown has Figure 8 The bag-shaped outer packaging component 2 shown in the figure. Figure 8 and Figure 9 The electrode assembly 1 and the electrolyte (not shown) are shown. The electrode assembly 1 and the electrolyte are housed within a bag-shaped outer packaging component 2. The electrolyte (not shown) is held within the electrode assembly 1.

[0168] The bag-shaped outer packaging component 2 is made of a laminated film containing two resin layers and a metal layer sandwiched between them.

[0169] like Figure 8 As shown, electrode assembly 1 is a flat, wound electrode assembly. Flat and wound electrode assembly 1 is as follows... Figure 9 As shown, it includes a negative electrode 3, a separator 4, and a positive electrode 5. The separator 4 is sandwiched between the negative electrode 3 and the positive electrode 5.

[0170] The negative electrode 3 includes a negative electrode current collector 3a and a negative electrode active material containing a layer 3b. The outermost portion of the negative electrode 3 located in the wound electrode assembly 1 is as follows: Figure 9 As shown, the negative electrode active material containing layer 3b is formed only on the inner surface side of the negative electrode current collector 3a. In other parts of the negative electrode 3, the negative electrode active material containing layer 3b is formed on both sides of the negative electrode current collector 3a.

[0171] The positive electrode 5 includes a positive current collector 5a and a positive active material containing layer 5b formed on both sides thereon.

[0172] like Figure 8 As shown, the negative terminal 6 and the positive terminal 7 are located near the outer periphery of the wound electrode assembly 1. The negative terminal 6 is connected to the outermost portion of the negative current collector 3a. Similarly, the positive terminal 7 is connected to the outermost portion of the positive current collector 5a. These negative terminals 6 and positive terminals 7 extend to the outside from the opening of the bag-shaped outer packaging member 2. A thermoplastic resin layer is provided on the inner surface of the bag-shaped outer packaging member 2, and the opening is sealed by thermal fusion bonding.

[0173] The secondary battery in the second embodiment is not limited to... Figure 8 and Figure 9 The secondary battery shown in the diagram could also be, for example, a... Figure 10 and Figure 11 The battery configuration shown is shown.

[0174] Figure 10 This is a partial cutaway perspective view schematically illustrating other examples of the secondary battery of the second embodiment. Figure 11 It is Figure 10 The cross-sectional view of part B of the secondary battery shown is magnified.

[0175] Figure 10 and Figure 11 The secondary battery 100 shown has Figure 10 and Figure 11 Electrode group 1 shown Figure 10 The outer packaging component 2 and the electrolyte (not shown) are shown. The electrode assembly 1 and the electrolyte are housed within the outer packaging component 2. The electrolyte is held within the electrode assembly 1.

[0176] The outer packaging component 2 is made of a laminated film containing two resin layers and a metal layer sandwiched between them.

[0177] Electrode group 1 as follows Figure 11 The electrode assembly shown is a stacked type. The stacked type electrode assembly 1 has a structure in which the negative electrode 3 and the positive electrode 5 are alternately stacked while the diaphragm 4 is sandwiched between them.

[0178] The electrode assembly 1 includes multiple negative electrodes 3. Each negative electrode 3 has a negative current collector 3a and a negative active material containing layer 3b supported on both sides of the negative current collector 3a. Furthermore, the electrode assembly 1 includes multiple positive electrodes 5. Each positive electrode 5 has a positive current collector 5a and a positive active material containing layer 5b supported on both sides of the positive current collector 5a.

[0179] Each negative electrode 3 has a negative current collector 3a containing a portion of its side surface that does not support the negative electrode active material, specifically a layer 3b. This portion functions as a negative current collector tab 3c. Figure 11 As shown, the negative electrode collector tab 3c does not overlap with the positive electrode 5. Furthermore, multiple negative electrode collector tabs 3c are electrically connected to the strip-shaped negative terminal 6. The front end of the strip-shaped negative terminal 6 is led out to the outside of the outer packaging member 2.

[0180] Furthermore, although not shown, each positive electrode 5's positive current collector 5a includes a portion on one side of which does not support the positive electrode active material containing layer 5b. This portion functions as a positive current collector tab. The positive current collector tab, like the negative current collector tab 3c, does not overlap with the negative electrode 3. Moreover, the positive current collector tab is located on the opposite side of electrode group 1 relative to the negative current collector tab 3c. The positive current collector tab is electrically connected to the strip-shaped positive terminal 7. The front end of the strip-shaped positive terminal 7 is located on the opposite side of the negative terminal 6 and is led out to the outside of the outer packaging member 2.

[0181] The secondary battery of the second embodiment includes at least one of the electrodes of the first embodiment as a positive electrode and a negative electrode. Therefore, the secondary battery of the second embodiment has excellent input / output performance.

[0182] [Third Implementation]

[0183] According to a third embodiment, a battery pack is provided. The battery pack of the third embodiment includes a plurality of secondary batteries as described in the second embodiment.

[0184] In the battery pack of the third embodiment, each individual battery can be electrically connected in series or in parallel, or a combination of series and parallel connections can be configured.

[0185] Next, an example of the battery pack of the third embodiment will be described with reference to the accompanying drawings.

[0186] Figure 12 This is a perspective view that schematically represents an example of a battery pack according to the third embodiment. Figure 12 The battery pack 200 shown includes five individual cells 100a to 100e, four busbars 21, a positive electrode lead 22, and a negative electrode lead 23. Each of the five individual cells 100a to 100e is a secondary battery according to the second embodiment.

[0187] Busbar 21 connects, for example, the negative terminal 6 of one single cell 100a to the positive terminal 7 of the adjacent single cell 100b. In this manner, five single cells 100 are connected in series via four busbars 21. That is, Figure 12 The battery pack 200 consists of five batteries connected in series. Although no example is shown, in a battery pack containing multiple individual cells electrically connected in parallel, for example, multiple negative terminals are connected to each other via busbars, and multiple positive terminals are connected to each other via busbars, thus allowing multiple individual cells to be electrically connected.

[0188] The positive terminal 7 of at least one of the five individual cells 100a to 100e is electrically connected to the positive terminal lead 22 for external connection. In addition, the negative terminal 6 of at least one of the five individual cells 100a to 100e is electrically connected to the negative terminal lead 23 for external connection.

[0189] The battery pack of the third embodiment includes the secondary battery of the second embodiment. Therefore, the battery pack has excellent input / output performance.

[0190] [Fourth Implementation]

[0191] According to a fourth embodiment, a battery pack is provided. This battery pack includes the battery pack of the third embodiment. Alternatively, the battery pack may include a single secondary battery of the second embodiment instead of the battery pack of the third embodiment.

[0192] The battery pack in the fourth embodiment may further include a protection circuit. This protection circuit has the function of controlling the charging and discharging of the secondary battery. Alternatively, a circuit included in a device that uses the battery pack as a power source (e.g., an electronic device, a car, etc.) may be used as the protection circuit for the battery pack.

[0193] Furthermore, the battery pack in the fourth embodiment may further include an external terminal for power supply. The external terminal for power supply is a component for outputting current from the secondary battery to the outside and / or for inputting current from the outside to the secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the outside via the external terminal for power supply. Furthermore, when the battery pack is being charged, charging current (including regenerative energy from the power source of an automobile, etc.) is supplied to the battery pack via the external terminal for power supply.

[0194] Next, an example of the battery pack according to the fourth embodiment will be described with reference to the accompanying drawings.

[0195] Figure 13 This is an exploded perspective view schematically illustrating an example of a battery pack according to the fourth embodiment. Figure 14 It means Figure 13 The diagram shows a block diagram of an example of the circuitry for the battery pack.

[0196] Figure 13 and Figure 14 The battery pack 300 shown includes a container 31, a cover 32, a protective sheet 33, a battery pack 200, a printed wiring board 34, wiring 35, and an insulating plate (not shown).

[0197] Figure 13 The container 31 shown is a square container with a rectangular base. The container 31 is configured to house the protective sheet 33, the battery pack 200, the printed wiring board 34, and the wiring 35. The cover 32 has a rectangular shape. The cover 32 houses the battery pack 200 and the like by covering the container 31. Although not shown, the container 31 and the cover 32 are provided with openings or connection terminals for connecting to external devices.

[0198] The battery pack 200 includes multiple individual cells 100, positive electrode side lead 22, negative electrode side lead 23, and adhesive tape 24.

[0199] At least one of the plurality of individual cells 100 is a secondary battery according to the second embodiment. Each of the plurality of individual cells 100 is as follows: Figure 14 As shown, the individual cells 100 are electrically connected in series. Multiple individual cells 100 can also be connected in parallel, or a combination of series and parallel connections can be used. If multiple individual cells 100 are connected in parallel, the battery capacity increases compared to a series connection.

[0200] Adhesive tape 24 is used to bundle multiple individual cells 100 together. Alternatively, heat shrink tape can be used to secure the multiple individual cells 100 instead of adhesive tape 24. In this case, protective sheets 33 are placed on both sides of the battery pack 200, and the heat shrink tape is wrapped around the pack and then heat-shrinked to bundle the multiple individual cells 100 together.

[0201] One end of the positive electrode lead 22 is connected to the battery pack 200. One end of the positive electrode lead 22 is electrically connected to the positive electrode of one or more individual cells 100. One end of the negative electrode lead 23 is connected to the battery pack 200. One end of the negative electrode lead 23 is electrically connected to the negative electrode of one or more individual cells 100.

[0202] The printed wiring substrate 34 is disposed on a surface along one short side of the inner side of the receiving container 31. The printed wiring substrate 34 includes a positive-side connector 342, a negative-side connector 343, a thermistor 345, a protection circuit 346, wirings 342a and 343a, an external terminal 350 for power supply, positive-side wiring 348a, and negative-side wiring 348b. One main surface of the printed wiring substrate 34 faces one side of the battery pack 200. An insulating plate (not shown) is sandwiched between the printed wiring substrate 34 and the battery pack 200.

[0203] The other end 22a of the positive lead 22 is electrically connected to the positive connector 342. The other end 23a of the negative lead 23 is electrically connected to the negative connector 343.

[0204] A thermistor 345 is fixed to a main surface of the printed wiring substrate 34. The thermistor 345 detects the temperature of each individual cell 100 and sends its detection signal to the protection circuit 346.

[0205] An external terminal 350 for power supply is fixed to another main surface of the printed wiring substrate 34. The external terminal 350 for power supply is electrically connected to a device located outside the battery pack 300. The external terminal 350 for power supply includes a positive terminal 352 and a negative terminal 353.

[0206] The protection circuit 346 is fixed to another main surface of the printed wiring substrate 34. The protection circuit 346 is connected to the positive terminal 352 via a positive side wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via a negative side wiring 348b. Furthermore, the protection circuit 346 is electrically connected to the positive connector 342 via wiring 342a. The protection circuit 346 is electrically connected to the negative connector 343 via wiring 343a. Moreover, the protection circuit 346 is electrically connected to each of the plurality of individual cells 100 via wiring 35.

[0207] The protective sheet 33 is disposed on the two inner sides of the receiving container 31 along the long side and on the inner side of the battery pack 200 opposite to the printed wiring substrate 34 along the short side. The protective sheet 33 is formed, for example, from resin or rubber.

[0208] The protection circuit 346 controls the charging and discharging of multiple individual batteries 100. In addition, based on the detection signal sent from the thermistor 345, or the detection signal sent from each individual battery 100 or battery pack 200, the protection circuit 346 blocks the electrical connection between the protection circuit 346 and the external terminals 350 (positive terminal 352, negative terminal 353) used to power external devices.

[0209] As a detection signal sent from the thermistor 345, examples include signals indicating that the temperature of a single cell 100 is above a predetermined temperature. As a detection signal sent from each single cell 100 or the battery pack 200, examples include signals indicating overcharging, over-discharging, and overcurrent of a single cell 100. In the case of detecting overcharging in each single cell 100, the battery voltage, or the positive or negative electrode potential, can be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each single cell 100.

[0210] It should be noted that the protection circuit 346 can also be a circuit contained in a device that uses the battery pack 300 as a power source (such as electronic equipment, automobiles, etc.).

[0211] Furthermore, as described above, the battery pack 300 includes an external terminal 350 for power supply. Therefore, the battery pack 300 can output current from the battery pack 200 to an external device and input current from an external device to the battery pack 200 via the external terminal 350. In other words, when the battery pack 300 is used as a power source, current from the battery pack 200 is supplied to the external device via the external terminal 350. Furthermore, when the battery pack 300 is being charged, charging current from the external device is supplied to the battery pack 300 via the external terminal 350. When the battery pack 300 is used as a vehicle battery, the regenerative energy from the vehicle's power source can be utilized as the charging current from the external device.

[0212] It should be noted that the battery pack 300 may also include multiple battery groups 200. In this case, the multiple battery groups 200 may be connected in series, in parallel, or a combination of series and parallel connections. Furthermore, the printed wiring board 34 and wiring 35 may be omitted. In this case, the positive lead 22 and the negative lead 23 may be used as the positive and negative terminals of the external terminals for power supply, respectively.

[0213] Such battery packs are used, for example, in applications requiring excellent cycle performance when drawing high currents. Specifically, they are used as power sources for electronic devices, stationary batteries, and in-vehicle batteries for various vehicles. Examples of electronic devices include digital cameras. This battery pack is particularly suitable for use as an in-vehicle battery.

[0214] The battery pack of the fourth embodiment includes the secondary battery of the second embodiment or the battery pack of the third embodiment. Therefore, the battery pack has excellent input / output performance.

[0215] [Fifth Implementation]

[0216] According to a fifth embodiment, a vehicle is provided. This vehicle is equipped with a battery pack according to a fourth embodiment.

[0217] In the vehicle of the fifth embodiment, the battery pack, for example, recovers regenerative energy from the vehicle's kinetic energy. The vehicle may also include a mechanism (regenerator) that converts the vehicle's kinetic energy into regenerative energy.

[0218] Examples of vehicles in the fifth embodiment include two- to four-wheeled hybrid electric vehicles, two- to four-wheeled electric vehicles, electric bicycles, and railway vehicles.

[0219] The mounting location of the battery pack in the vehicle according to the fifth embodiment is not particularly limited. For example, when mounting the battery pack in a car, the battery pack can be mounted in the engine compartment, at the rear of the vehicle body, or under the seats.

[0220] The vehicle in the fifth embodiment can also be equipped with multiple battery packs. In this case, the batteries contained in each battery pack can be electrically connected in series, in parallel, or a combination of series and parallel connections. For example, when each battery pack contains battery groups, the battery groups can be electrically connected in series, in parallel, or a combination of series and parallel connections. Alternatively, when each battery pack contains a single battery, the batteries can be electrically connected in series, in parallel, or a combination of series and parallel connections.

[0221] Next, an example of the vehicle according to the fifth embodiment will be described with reference to the accompanying drawings.

[0222] Figure 15 This is a partial perspective view that schematically represents an example of a vehicle according to the fifth embodiment.

[0223] Figure 15 The vehicle 400 shown includes a vehicle body 40 and a battery pack 300 according to the fourth embodiment. Figure 15 In the example shown, vehicle 400 is a four-wheeled car.

[0224] The vehicle 400 can also be equipped with multiple battery packs 300. In this case, the batteries (e.g., single cells or groups of cells) contained in the battery pack 300 can be connected in series, in parallel, or a combination of series and parallel connections.

[0225] Figure 15 The diagram illustrates an example where the battery pack 300 is mounted in the engine compartment located at the front of the vehicle body 40. As mentioned above, the battery pack 300 can also be mounted, for example, at the rear of the vehicle body 40 or under the seats. The battery pack 300 can be used as a power source for the vehicle 400. Furthermore, the battery pack 300 is capable of recovering regenerative energy from the power source of the vehicle 400.

[0226] Next, refer to Figure 16 The implementation scheme of the vehicle in the fifth embodiment will be described.

[0227] Figure 16 This is a diagram that schematically illustrates an example of a control system for the electrical system in a vehicle according to the fifth embodiment. Figure 16 The vehicle 400 shown is an electric vehicle.

[0228] Figure 16 The vehicle 400 shown includes a vehicle body 40, a vehicle power supply 41, a vehicle ECU (Electric Control Unit) 42 which serves as a higher-level control device for the vehicle power supply 41, external terminals (terminals for connecting to an external power source) 43, an inverter 44, and a drive motor 45.

[0229] Vehicle 400 mounts vehicle power supply 41 in, for example, the engine compartment, the rear of the vehicle body, or under the seats. It should be noted that... Figure 16 In the vehicle 400 shown, the mounting location of the vehicle power supply 41 is roughly indicated.

[0230] The vehicle power supply 41 includes multiple (e.g., three) battery packs 300a, 300b and 300c, a battery management unit (BMU) 411 and a communication bus 412.

[0231] Battery pack 300a includes battery pack 200a and battery pack monitoring device 301a (e.g., VTM: Voltage Temperature Monitoring). Battery pack 300b includes battery pack 200b and battery pack monitoring device 301b. Battery pack 300c includes battery pack 200c and battery pack monitoring device 301c. Battery packs 300a to 300c are the same type of battery pack as battery pack 300 described above, and battery packs 200a to 200c are the same type of battery pack as battery pack 200 described above. Battery packs 200a to 200c are electrically connected in series. Battery packs 300a, 300b, and 300c can be removed independently and can be exchanged with other battery packs 300.

[0232] Each of the battery packs 200a to 200c comprises a plurality of individual cells connected in series. At least one of the individual cells is a secondary battery according to the second embodiment. The battery packs 200a to 200c are charged and discharged via the positive terminal 413 and the negative terminal 414, respectively.

[0233] The battery management device 411 communicates with the battery pack monitoring devices 301a-301c to collect information on voltage, temperature, and other parameters for each individual cell 100 contained in the battery packs 200a-200c included in the vehicle power supply 41. Thus, the battery management device 411 collects maintenance information regarding the vehicle power supply 41.

[0234] The battery management device 411 and the battery monitoring devices 301a-301c are connected via a communication bus 412. In the communication bus 412, one set of communication lines is shared by multiple nodes (the battery management device 411 and one or more battery monitoring devices 301a-301c). The communication bus 412 is, for example, a communication bus based on the CAN (Control Area Network) standard.

[0235] The battery monitoring devices 301a to 301c measure the voltage and temperature of each individual cell constituting the battery packs 200a to 200c based on instructions received via communication from the battery management device 411. However, the temperature may be measured at multiple locations for only one battery pack, or the temperature of all individual cells may not be measured.

[0236] The vehicle power supply 41 may also have an electromagnetic contactor (e.g., to switch the electrical connection between the positive terminal 413 and the negative terminal 414) to enable or disable the connection. Figure 16The switching device 415 shown is included. The switching device 415 includes a pre-charge switch (not shown) that is turned on when charging the battery packs 200a-200c, and a main switch (not shown) that is turned on when supplying output from the battery packs 200a-200c to a load. Both the pre-charge switch and the main switch have relay circuits (not shown) that are switched on or off by signals supplied to coils located near the switching elements. The electromagnetic contactors, such as the switching device 415, are controlled based on control signals from the vehicle ECU 42 that control the operation of the battery management device 411 or the vehicle 400 as a whole.

[0237] Inverter 44 converts the input DC voltage into a high-voltage 3-phase AC voltage for motor drive. The 3-phase output terminals of inverter 44 are connected to the 3-phase input terminals of drive motor 45. Inverter 44 is controlled based on control signals from vehicle ECU 42 used to control the operation of battery management device 411 or the vehicle as a whole. By controlling inverter 44, the output voltage from inverter 44 is adjusted.

[0238] The drive motor 45 rotates by electricity supplied by the inverter 44. The driving force generated by the rotation of the drive motor 45 is transmitted to the axle and drive wheel W, for example, through a differential gear unit.

[0239] Furthermore, although not shown, vehicle 400 is equipped with a regenerative braking mechanism. When braking vehicle 400, the regenerative braking mechanism (e.g., a regenerator) causes drive motor 45 to rotate, converting kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative braking mechanism is input to inverter 44 and converted into direct current. The converted direct current is input to vehicle power supply 41.

[0240] One terminal of the connecting line L1 is connected to the negative terminal 414 of the vehicle power supply 41. The other terminal of the connecting line L1 is connected to the negative input terminal 417 of the inverter 44. A current detection unit (current detection circuit) 416 of the battery management device 411 is provided on the connecting line L1 between the negative terminal 414 and the negative input terminal 417.

[0241] A terminal of a connecting wire L2 is connected to the positive terminal 413 of the vehicle power supply 41. The other terminal of the connecting wire L2 is connected to the positive input terminal 418 of the inverter 44. A switching device 415 is provided on the connecting wire L2 between the positive terminal 413 and the positive input terminal 418.

[0242] External terminal 43 is connected to battery management device 411. External terminal 43 can be connected to an external power source, for example.

[0243] The vehicle ECU 42 responds to input from the driver and other operators, and coordinates with other management and control devices, including the battery management device 411, to control the vehicle power supply 41, switching device 415, and inverter 44. Through the coordinated control of the vehicle ECU 42 and others, it controls the output of power from the vehicle power supply 41 and the charging of the vehicle power supply 41, thus managing the overall vehicle 400. Data related to the maintenance of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is transmitted between the battery management device 411 and the vehicle ECU 42 via a communication line.

[0244] The vehicle of the fifth embodiment is equipped with the battery pack of the fourth embodiment. Therefore, due to the battery pack having excellent input / output performance, it can exhibit high performance.

[0245] [Example]

[0246] The following describes the embodiments, but the present invention is not limited to the embodiments described below as long as it does not depart from the spirit of the present invention.

[0247] Electrode fabrication

[0248] (Example 1)

[0249] First, inorganic solid particles were mixed into N-methyl-2-pyrrolidone at a solid content of 60%, and dispersed using an Ashizawa Finetech Star Mill LME4 bead mill to prepare the first slurry. The first slurry was prepared under dispersion conditions of 0.1 mm bead diameter, 60% bead filling rate, and 700 rpm stirring speed. The inorganic solid particles used had an average particle size of 0.5 μm and a lithium-ion conductivity of 1 × 10⁻⁶. -4 Li in S / cm 1.5 Al 0.5 Ti 1.5 (PO4)3. Hereinafter, this inorganic solid particle will be designated as LATPO1.

[0250] The active material, granular carbon, and binder were mixed in the first slurry. After stirring the mixture using a planetary mixer, it was further stirred using a bead mill to prepare the second slurry. The second slurry was prepared under dispersion conditions of Φ2 mm beads, 60% bead filling rate, and 1000 rpm stirring speed. As the active material, a lithium-containing nickel-manganese-cobalt composite oxide (LiNi) with an average particle size of 6.4 μm was used. 0.5 Mn 0.2 Co 0.3O2 particles. Acetylene black with an average particle size of 0.2 μm was used as granular carbon. Polyvinylidene fluoride was used as a binder. In the second slurry, the amounts of inorganic solid particles, granular carbon, and binder relative to 100 parts by mass of active material were 3 parts by mass, 3 parts by mass, and 2 parts by mass, respectively.

[0251] Next, the second slurry was coated onto both sides of the current collector and allowed to dry, resulting in an active material containing layer. An aluminum alloy foil with a thickness of 12 μm was used as the current collector. The current collector and the active material containing layer were then pressed to obtain the electrode. The density of the active material containing layer was 3.3 g / cm³. 3 .

[0252] (Examples 2-3)

[0253] In Examples 2 and 3, the stirring conditions using a bead mill during the preparation of the second slurry were changed as shown in Table 1 below. Otherwise, the electrodes were fabricated using the same steps as in Example 1.

[0254] (Examples 4-7)

[0255] In Examples 4-7, LATPO1 was used instead of inorganic solid particles, and particles with an average particle size of 0.7 μm and a lithium-ion conductivity of 1 × 10⁻⁶ were used. -4 Li in S / cm 1.5 Al 0.5 Ti 1.5 (PO4)3. Hereinafter, the inorganic solid particle will be designated as LATPO2. In Examples 4-7, LATPO2 was used instead of LATPO1, and the conditions for bead mill dispersion during the preparation of the first slurry were changed as shown in Table 1 below. Otherwise, the electrodes were prepared using the same steps as in Example 1.

[0256] (Comparative Examples 1-2)

[0257] In Comparative Examples 1-2, the conditions of bead mill dispersion in preparing the first slurry or stirring treatment using a bead mill in preparing the second slurry were changed as shown in Table 1 below. Otherwise, the electrodes were fabricated using the same steps as in Example 1.

[0258] Table 1 below summarizes the electrode fabrication conditions in each embodiment and comparative example. Specifically, it shows the average particle size of LATPO1 and LATPO2, used as inorganic solid particles, before bead milling, the bead milling dispersion conditions during the preparation of the first slurry, and the bead milling stirring conditions during the preparation of the second slurry. The bead milling conditions for the preparation of the first and second slurries are shown, including the bead diameter, bead filling rate, and stirring speed.

[0259] Table 1

[0260]

[0261] Determination of Logarithmic Differential Pore Volume Distribution Curve

[0262] Using the method described above, the logarithmic differential pore volume distribution curves of the active material containing layer prepared in Examples 1-7 and Comparative Examples 1-2 were measured using the mercury intrusion method. For the active material containing layer of any electrode, the highest peak of logarithmic differential pore volume (the first peak) appeared in the range of 0.05 μm to 10 μm. From the obtained logarithmic differential pore volume distribution curves, the first pore volume corresponding to the highest intensity peak (the first peak) and the second pore volume in the range of 0.005 μm to 0.02 μm were determined, and the ratio of the first pore volume to the total pore volume and the ratio of the second pore volume to the first pore volume were calculated, respectively. The results are shown in Table 2 below.

[0263] <Input / Output Performance Evaluation>

[0264] A two-pole coin cell was fabricated, and its input / output performance (speed performance) was evaluated. For the working electrode, the electrodes fabricated in Examples 1-7 and Comparative Examples 1-2 were used. The electrode size was set to a circular shape with a diameter of 14 mm. For the counter electrode, lithium metal was used. As the electrolyte, a solution obtained by dissolving lithium hexafluoride phosphate (LiPF6) in a mixed solvent of ethylene carbonate and diethyl carbonate was used. The ratio of ethylene carbonate to diethyl carbonate in the mixed solvent was set to 1:2. The concentration of LiPF6 was set to 1 mol / L. The amount of electrolyte was set to 200 μL.

[0265] First, the fabricated coin cell was charged at 25°C with a current density of 1C until the State of Charge (SOC) reached 100%. Then, it was discharged at a current density of 1C until the SOC reached 0%, and the 1C discharge capacity was measured. Next, it was charged again at a current density of 1C until the SOC reached 100%. Then, it was discharged at a current density of 3C until the SOC reached 0%, and the 3C discharge capacity was measured. The 3C / 1C rate-capacity ratio was calculated by dividing the 3C discharge capacity by the 1C discharge capacity. The results are shown in Table 2.

[0266] Table 2

[0267]

[0268] As shown in Table 2, the electrodes fabricated in Examples 1-7 exhibit superior input / output performance compared to the electrodes fabricated in Comparative Examples 1-2. Regarding the electrodes fabricated in Examples 1-7, the first peak in the logarithmic differential pore volume distribution curve obtained using the mercury indentation method, with the maximum logarithmic differential pore volume as its apex, has a first pore volume with a ratio of 20% to 50% relative to the total pore volume. Furthermore, the ratio of the second pore volume (0.005 μm to 0.02 μm) to the first pore volume is within the range of 0.1% to 5%. In contrast, for Comparative Examples 1 and 2, the ratio of the second pore volume to the first pore volume is 0%. Moreover, for the electrode fabricated in Comparative Example 2, the first pore volume also exceeds 50% of the total pore volume.

[0269] In Comparative Example 1, the low stirring speed during bead mill dispersion in the preparation of the first slurry caused the inorganic solid particles (LATPO1) to agglomerate in the first slurry. That is, the inorganic solid particles could not be uniformly dispersed, resulting in poor input and output performance of the electrode.

[0270] In Comparative Example 2, the low stirring speed during the bead milling process in the preparation of the second slurry led to the aggregation of inorganic solid particles (LATPO1) in the second slurry. Furthermore, it was found that due to the high proportion of the first pore volume derived from the active material, good compatibility between the active material, inorganic solid particles, and carbon material was not achieved. As a result, the input / output performance of the electrode was not excellent.

[0271] According to at least one embodiment and example described above, an electrode having an active material containing layer is provided. The active material containing layer comprises an active material, inorganic solid particles with lithium-ion conductivity, and a carbon material. The active material containing layer exhibits a first peak representing the maximum logarithmic differential pore volume in a logarithmic differential pore volume distribution curve obtained using mercury indentation. The pore diameter D1 of the first peak is 0.05 μm to 10 μm, and the first pore volume corresponding to the first peak is 20% to 50% of the total pore volume. A second pore volume in the range of 0.005 μm to 0.02 μm is 0.1% to 5% of the first pore volume. This electrode exhibits excellent input / output performance, enabling the provision of secondary batteries and battery packs with excellent input / output performance, as well as vehicles equipped with such battery packs.

[0272] It should be noted that the above-described implementation methods can be summarized into the following technical solutions.

[0273] (Technical Solution 1)

[0274] An electrode includes an active material containing an active material layer comprising an active material, inorganic solid particles with lithium-ion conductivity, and a carbon material. The active material containing layer exhibits a first peak representing the maximum logarithmic differential pore volume in a logarithmic differential pore volume distribution curve obtained using mercury indentation. The pore diameter D1 of the first peak is 0.05 μm to 10 μm. The first pore volume corresponding to the first peak is 20% to 50% of the total pore volume in the active material containing layer, and a second pore volume in the range of 0.005 μm to 0.02 μm is 0.1% to 5% of the first pore volume.

[0275] (Technical Solution 2)

[0276] According to the above technical solution 1, the active material contains particles with an average primary particle size of 1 μm to 20 μm, and the inorganic solid particles have an average primary particle size of 0.2 μm to 2 μm.

[0277] (Technical Solution 3)

[0278] According to the above technical solution 1 or 2, the above active material comprises a lithium-containing transition metal composite oxide.

[0279] (Technical Solution 4)

[0280] A secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein at least one of the positive electrode and the negative electrode is an electrode as described in any one of the above-described technical solutions 1 to 3.

[0281] (Technical Solution 5)

[0282] A battery pack comprising the secondary battery described in technical solution 4 above.

[0283] (Technical Solution 6)

[0284] According to the above technical solution 5, it further includes external terminals for power supply and protection circuit.

[0285] (Technical Solution 7)

[0286] According to the above technical solution 5 or 6, it has multiple secondary batteries, which are electrically connected in series, in parallel, or in a combination of series and parallel connections.

[0287] (Technical Solution 8)

[0288] A vehicle comprising a battery pack as described in any one of the above-mentioned technical solutions 5 to 7.

[0289] (Technical Solution 9)

[0290] According to the above technical solution 8, it includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

[0291] Several embodiments of the present invention have been described, but these embodiments are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the invention described in the claims and its equivalents.

Claims

1. An electrode comprising an active material containing an active material layer, inorganic solid particles having lithium-ion conductivity, and a carbon material. The active material containing layer exhibits a first peak representing the maximum logarithmic differential pore volume in the logarithmic differential pore volume distribution curve obtained using the mercury indentation method. The pore diameter D1 of the first peak is 0.05 μm to 10 μm. The first pore volume corresponding to the first peak accounts for 20% to 50% of the total pore volume in the active material containing layer. The cumulative pore volume in the range of pore diameters from 0.005 μm to 0.02 μm, i.e., the second pore volume, is 0.1% to 5% of the first pore volume. The active material comprises a lithium-containing transition metal complex oxide.

2. The electrode according to claim 1, wherein, The active material comprises particles with an average primary particle size of 1 μm to 20 μm, and the inorganic solid particles have an average primary particle size of 0.2 μm to 2 μm.

3. A secondary battery comprising: a positive electrode, a negative electrode, and an electrolyte. At least one of the positive electrode and the negative electrode is the electrode as described in claim 1 or 2.

4. A battery pack comprising the secondary battery as described in claim 3.

5. The battery pack according to claim 4, further comprising: an external terminal for power supply and a protection circuit.

6. The battery pack according to claim 4 or 5, comprising a plurality of said secondary batteries, The secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel connections.

7. A vehicle comprising the battery pack of any one of claims 4 to 6.

8. The vehicle of claim 7, further comprising a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

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