JP2012256509A - Method for manufacturing nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably manufacturing a nonaqueous secondary battery capable of exhibiting excellent performance under different operating conditions.SOLUTION: The method for manufacturing a nonaqueous secondary battery comprises the steps of: (A) preparing an electrode body in which at least one of electrodes comprises an active material layer containing active material particles and conductive material particles; and (B) building a nonaqueous secondary battery by installing the electrode body and a nonaqueous electrolyte in a battery case. The step (A) comprises the steps of: preparing an electrode mixture liquid (dispersions) in which the active material particles and the conductive material particles are dispersed in a liquid phase, and determining the state of dispersion of the electrode mixture liquid by measuring at least one of the particle size distribution, the zeta potential, and the electrical conductivity; and forming the active material layer using only the electrode mixture liquid whose determined state of dispersion satisfies a predetermined acceptance requirement.

Description

  The present invention relates to a method for producing a lithium ion secondary battery and other non-aqueous secondary batteries.

  Lithium ion secondary batteries and other non-aqueous secondary batteries are becoming increasingly important as power sources for vehicles or as power sources for personal computers and portable terminals. In particular, a lithium ion secondary battery that is lightweight and obtains a high energy density is expected to be preferably used as a high-output power source mounted on a vehicle. Patent documents 1 and 2 are mentioned as technical literature about a nonaqueous secondary battery.

JP 2007-335175 A JP 2009-224099 A

  Usually, non-aqueous secondary batteries have various usage conditions such as temperature and charge / discharge rate according to their applications. For this reason, as the demand for batteries that exhibit high performance even under more severe usage conditions increases, the conventional manufacturing method stably stabilizes batteries that exhibit desired characteristics under predetermined usage conditions (such as performance variations between production lots). However, there has been a situation in which battery performance varies greatly under more severe use conditions. Therefore, it would be beneficial to provide a method for stably producing a battery that can exhibit higher battery performance and that can exhibit better performance not only under mild conditions but also under severe conditions.

  Therefore, an object of the present invention is to provide a method for stably producing a non-aqueous secondary battery that can exhibit good performance even under different use conditions.

According to the technology disclosed herein, a method for manufacturing a non-aqueous secondary battery is provided. The method is
(A) preparing an electrode body provided with an active material layer in which at least one electrode includes active material particles and conductive material particles; and (B) housing the electrode body and the non-aqueous electrolyte in a battery container. And constructing a non-aqueous secondary battery. The step (A) comprises (i) preparing an electrode mixture liquid (dispersion) in which active material particles and conductive material particles are dispersed in a liquid phase for forming at least one of the electrodes; and (ii) It is carried out by grasping the dispersion state of the electrode mixture liquid. In (ii) of the above step (A), the dispersion state of the electrode mixture liquid is to measure at least one of particle size distribution, zeta potential, and conductivity (electrical conductivity) for the electrode mixture liquid. It is grasped by. The manufacturing method sends the electrode mixture liquid to the next step when the dispersion state of the electrode mixture liquid grasped in (ii) of the step (A) satisfies a preset acceptance condition, and the acceptance condition In the case where the above condition is not satisfied, the method further includes removing the electrode mixture solution from the next step; and forming the active material layer using the electrode mixture solution sent to the next step.

  According to the method disclosed here, the dispersion state of the conductive material particles in the electrode mixture liquid is grasped, and only the acceptance standard electrode mixture liquid is used in the next step. Therefore, more severe use conditions (low temperature (for example, −15 Non-aqueous secondary battery capable of exhibiting performance (capacity, capacity retention rate, etc.) above a certain standard even in rapid discharge (for example, about 3C), high temperature (for example, charge / discharge cycle at about 40 ° C), etc. Can be manufactured.

  In the present specification, the “secondary battery” refers to a general power storage device that can be repeatedly charged and discharged, and is a term including a so-called storage battery such as a lithium secondary battery and a power storage element such as an electric double layer capacitor. The “non-aqueous secondary battery” refers to a battery provided with a non-aqueous electrolyte (typically, an electrolyte containing a supporting salt (supporting electrolyte) in a non-aqueous solvent). A non-aqueous secondary battery including a non-aqueous electrolyte (that is, a non-aqueous electrolyte solution) that exhibits a liquid state at normal temperature (for example, 25 ° C.) is preferable. The “lithium secondary battery” refers to a secondary battery that uses lithium ions as electrolyte ions and is charged and discharged by the movement of lithium ions between the positive and negative electrodes. A secondary battery generally referred to as a lithium ion battery is a typical example included in the lithium secondary battery in this specification. The electrode active material refers to a material that can reversibly occlude and release chemical species (lithium ions in a lithium secondary battery) serving as a charge carrier.

  In one aspect, the total amount of solids in the electrode mixture solution (total solid component amount) is 100% by mass, and the content of the conductive material particles is about 0.5 to 10% by mass (more preferably, 6 to 6%). It is preferably about 8% by mass). According to this aspect, since the active material content in the active material layer can be increased, a battery with less performance variation and a higher capacity can be realized even under severe use conditions. Such a battery is suitable for uses such as a drive power source mounted on a vehicle, for example.

  In another aspect, the average size of the active material particles is preferably about 5 μm to 20 μm as an arithmetic average value (number average particle size) of the diameters of the plurality of active material particles measured by an optical microscope. . In such an aspect, it is particularly meaningful to employ the manufacturing method disclosed herein, and a non-aqueous secondary battery that can exhibit a certain level of performance even under more severe use conditions can be realized.

  In another aspect, the conductive material particles are preferably carbon particles having a structure in which a plurality of primary particles are connected. The average size of the carbon particles is preferably 0.1 μm to 4.0 μm as an arithmetic average value (number average particle size) of the lengths of the plurality of carbon particles measured by an optical microscope. In such an embodiment, it is particularly meaningful to employ the manufacturing method disclosed herein.

In another aspect, the particle size distribution is preferably measured by a dynamic light scattering method. In the measured particle size distribution, the maximum frequency (%) in the range of 0.1 μm or more and less than 1.0 μm is V _1MAX , and the maximum frequency (%) in the range of the particle size of 1.0 μm or more and less than 4.0 μm is V _{2MAX. as,} it is preferable that the ratio of _{V 2MAX} for _{V 1MAX (V 2MAX / V 1MAX} ) is to the pass condition that is within a predetermined numerical range. In one aspect, it is more preferable that the above-mentioned pass condition is that V _2MAX / V _1MAX is in the range of 0.2 to 20. According to such an embodiment, a non-aqueous secondary battery that can exhibit a certain level of performance even under more severe use conditions can be realized.

  In another aspect, the pass condition is preferably such that the zeta potential is in the range of −5 mV to −10 mV. According to such an embodiment, a non-aqueous secondary battery that can exhibit a certain level of performance even under more severe use conditions can be realized.

In another aspect, it is preferable that the electrical conductivity is in the range of 1 × 10 ^{−4 to} 5 × 10 ⁻⁴ S / m as the pass condition. According to such an embodiment, a non-aqueous secondary battery that can exhibit a certain level of performance even under more severe use conditions can be realized.

  A non-aqueous secondary battery manufactured by any of the methods disclosed herein stably realizes higher performance even under severer usage conditions (low temperature rapid discharge, high temperature charge / discharge cycle, etc.). obtain. Therefore, for example, it is suitable as a power source mounted on a vehicle. Accordingly, a non-aqueous secondary battery (typically a lithium ion secondary battery) disclosed herein is a power source (typically) for a motor mounted on a vehicle such as a hybrid vehicle or an automobile equipped with an electric motor such as an electric vehicle. In particular, it can be suitably used as a drive power source.

It is a perspective view which shows typically the external shape of the non-aqueous secondary battery which concerns on one Embodiment. It is the II-II sectional view taken on the line in FIG. It is a side view which shows typically the vehicle (automobile) provided with the non-aqueous secondary battery of this invention. It is a perspective view which shows typically the external shape of a 18650 type non-aqueous secondary battery. 4 is a particle size distribution chart measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 1. 5 is a particle size distribution chart measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 2. 5 is a particle size distribution chart measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 3. 5 is a particle size distribution chart measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 4. 10 is a chart of particle size distribution measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 5. 10 is a chart of particle size distribution measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 6. 10 is a chart of particle size distribution measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 7. 10 is a chart of particle size distribution measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 8. 10 is a particle size distribution chart measured by a dynamic light scattering method for the positive electrode mixture liquid according to Example 9.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. Moreover, in the following drawings, the same code | symbol is attached | subjected to the member and site | part which show | plays the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. The dimensional relationship (length, width, thickness, etc.) in each figure does not reflect the actual dimensional relationship.

  The technology disclosed herein can be widely applied to various nonaqueous secondary batteries including an electrode in a form in which an electrode active material layer is held on a current collector. By employing the method disclosed herein, it is possible to manufacture a non-aqueous secondary battery that can exhibit and maintain a certain capacity or more even under more severe use conditions. That is, the non-aqueous secondary battery manufactured by adopting the method disclosed herein has little performance variation between lots and can be used while maintaining high performance even under more severe conditions. Hereinafter, the present invention will be described in more detail mainly using a lithium ion secondary battery having a configuration in which the positive electrode includes a conductive material, but the application target of the present invention is not intended to be limited to such an electrode or battery.

As the conductive material particles, for example, a carbon material (carbon particles) having a structure in which a plurality of primary particles are linked (beaded) can be preferably used. An example of the carbon material having such a structure is acetylene black. The average size of the conductive material particles is determined by measuring the length of a plurality of conductive material particles (in the case of conductive material particles having a structure in which primary particles are connected) by measuring with an optical microscope. The arithmetic average value (number average particle diameter) of the result is preferably about 0.1 μm to 4.0 μm. When the average size of the conductive material particles is too large, the conductivity of the positive electrode active material layer may be uneven.
Conductive material particles having a structure in which primary particles are connected are dispersed between the positive electrode active material particles in a state where the beads are extended, so that an increase in electric resistance is suppressed and the active material particles are efficiently and electrically connected between the active material particles. Since they can be connected, excellent conductivity can be imparted to the active material layer even with a smaller amount of use. On the other hand, the bead-like structure tends to get tangled and rounded, and has a large specific surface area and is difficult to wet. Therefore, it tends to be difficult to disperse evenly in the stretched state as described above. In addition, when a binder is used to fix the positive electrode active material layer forming component, the conductive material is likely to be adsorbed on the binder at the stage of preparing the positive electrode mixture solution, so that the dispersion is good. It becomes more difficult to realize the state. In the case of using conductive material particles having such a structure, it is particularly meaningful to apply the technology disclosed herein because only the positive electrode mixture liquid in a good dispersion state can be sent to the next step (preparation of the positive electrode). It is.
The amount of the conductive material contained in the positive electrode active material layer is preferably about 0.5 to 10% by mass. Since the amount of the conductive material can be relatively reduced in this manner, the amount of the positive electrode active material contained in the positive electrode active material layer can be relatively increased, which is advantageous in increasing the battery capacity per volume. is there.

  As the positive electrode active material, a compound capable of inserting and extracting lithium is used, and one or more of various positive electrode active materials used in a general lithium ion secondary battery can be used. For example, a lithium-containing oxide having a layered structure or a spinel structure can be preferably used. More specifically, an oxide containing lithium and at least one transition metal, such as lithium nickel oxide, lithium cobalt oxide, and lithium manganese oxide, is exemplified.

Here, the lithium nickel oxide is an oxide having lithium (Li) and nickel (Ni) as constituent metal elements, and at least one other metal element other than lithium and nickel (that is, other than Li and Ni) The transition metal element and / or the typical metal element) is also meant to include an oxide containing the constituent metal element at a ratio equivalent to or less than nickel in terms of the number of atoms. Examples of the metal element other than Li and Ni include, for example, cobalt (Co), aluminum (Al), manganese (Mn), chromium (Cr), iron (Fe), vanadium (V), magnesium (Mg), and titanium (Ti ), Zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W), copper (Cu), zinc (Zn), gallium (Ga), indium (In), tin (Sn), lanthanum (La) And one or more metal elements selected from the group consisting of cerium (Ce). The same meaning is applied to lithium cobalt oxide and lithium manganese oxide. As a particularly preferable positive electrode active material, a lithium oxide containing Ni, Co, and Mn (for example, a lithium oxide containing approximately the same amount of three elements of Ni, Co, and Mn in terms of the number of atoms) is exemplified.
Further, an olivine type lithium phosphate represented by the general formula LiMPO ₄ (M is at least one element of Co, Ni, Mn, and Fe; for example, LiFePO ₄ , LiMnPO ₄ ) is used as the positive electrode active material. Also good.

Preferably, a positive electrode active material prepared in the form of particles is used. The average size of the positive electrode active material particles is preferably about 5 μm to 20 μm as an arithmetic average value of the diameters of the plurality of active material particles measured by an optical microscope. By using the active material particles having such a size and setting the average size of the conductive material particles within the above preferable range, the conductive material particles having a size smaller than that of the active material particles are preferably used in the gaps between the positive electrode active material particles. Can be dispersed. Further, in this aspect, since the particle size distribution of the active material particles and the particle size distribution of the conductive material particles do not substantially overlap, the particle size distribution is measured by a method described later to pay particular attention to the dispersed state of the conductive material particles. Thus, it can be easy to grasp the dispersion state of the positive electrode mixture liquid.
The amount of the positive electrode active material contained in the positive electrode active material layer can be, for example, about 50 to 95% by mass (preferably about 75 to 95% by mass).

The positive electrode mixture liquid may contain a binder as necessary. As a binder, it can select from various polymers suitably and can be used. Only one kind may be used alone, or two or more kinds may be used in combination.
For example, water-soluble polymers such as carboxymethylcellulose (CMC), methylcellulose (MC), cellulose acetate phthalate (CAP), hydroxypropylmethylcellulose (HPMC), hydroxypropylmethylcellulose phthalate (HPMCP), polyvinyl alcohol (PVA); Fluorine such as fluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), etc. Resin, vinyl acetate copolymer, styrene butadiene block copolymer (SBR), acrylic acid-modified SBR resin (SBR latex), rubbers (such as gum arabic), Dispersible polymers; oil-soluble polymers such as polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene oxide-propylene oxide copolymer (PEO-PPO); Etc.
What is necessary is just to select the quantity of the binder contained in a positive electrode active material layer suitably according to the kind and quantity of an active material and a electrically conductive material.

  The liquid phase (dispersion medium) in which these positive electrode materials are dispersed may be appropriately selected according to the type of the positive electrode material, and a dispersion medium conventionally used when producing a positive electrode of a general lithium ion secondary battery. Can be used alone or in combination. For example, N-methyl-2-pyrrolidone (NMP) can be preferably used.

  In the technique disclosed herein, a positive electrode mixture liquid in which the positive electrode material is dispersed in the dispersion medium is prepared. The positive electrode mixture solution can be prepared by an appropriate method. For example, a method in which a conductive material and a binder used as needed are pre-dispersed in a dispersion medium and then a positive electrode active material is added afterwards; a solid component of a positive electrode mixture liquid (positive electrode active material, conductive material, necessary A binder or other positive electrode active material layer forming component) used in accordance with the amount of the mixture and kneading with a small amount of dispersion medium, and further adding the dispersion medium to dilute to a desired solid content concentration; Stirrer (Primix Co., Ltd.) And the like.

The positive electrode active material is added after the conductive material, which is relatively difficult to disperse, is sufficiently dispersed in a sufficient amount of dispersion medium (a larger amount than the kneading) in the preliminary dispersion step, and then the positive electrode active material is dry-processed. Addition is preferable in that it is easy to obtain a positive electrode mixture liquid in which the conductive material is well dispersed even if the solid content concentration is set high. The method of diluting after solidifying has the advantage that a desired solid content concentration can be obtained by dilution after preliminarily dispersing by applying appropriate shear stress at the stage of solidifying. In this method, for example, it is appropriate that the solid content concentration at the time of solidification is about 65 to 75% and the solid content concentration after dilution is about 50 to 55%. In the method using a stirrer, by applying a shear stress locally so that the paste contacts only the tip of the stirring blade, the stirring can be performed efficiently, and a desired dispersion state and solid content concentration are realized. There is an advantage that you can.
Methods other than these may be employed for preparing the positive electrode mixture solution. In the manufacturing method disclosed herein, since acceptable conditions that can realize a desired dispersion state are set, various parameters of the dispersion conditions (stirring speed, time, temperature, etc.) are adjusted to satisfy the acceptable conditions. Therefore, the method for preparing the positive electrode mixture liquid is not particularly limited.

  The dispersion state of the electrode mixture liquid can be grasped by measuring at least one of the particle size distribution, zeta potential, and conductivity of the mixture liquid sample.

  The particle size distribution of the electrode mixture liquid can be preferably measured by, for example, a dynamic light scattering method to which a photon correlation method is applied. A measuring instrument based on this principle and having a desired resolution (at least the measurement range includes a particle size of 0.1 μm to 4.0 μm) can be used without particular limitation. For example, the model “UPA-150EX” manufactured by Microtrack (USA) or its equivalent can be used.

When the particle size distribution is adopted as an index for grasping the dispersion state of the positive electrode mixture liquid, in the particle size distribution chart in which the frequency (%) (volume basis) with respect to the particle size (μm) is plotted, 0.1 μm or more The maximum frequency (%) in the range less than 1.0 μm (first particle size range) is V _1MAX , and the maximum frequency (%) in the range from 1.0 μm to less than 4.0 μm (second particle size range) is V _2MAX . _when, that the value of the ratio of _{V 2MAX} for _{V 1MAX (V 2MAX / V 1MAX} ) is within a predetermined range can be set as a pass condition for positive electrode material liquid. The acceptable range is a correlation between V _2MAX / V _1MAX measured for a plurality of positive electrode mixture liquid samples with different preparation conditions (stirring time, speed, etc.) and the performance of the battery using the corresponding positive electrode mixture liquid. Can be determined based on For example, positive electrode mixture liquids with different stirring times at a predetermined speed are prepared, and the V _2MAX / V _1MAX of each positive electrode mixture liquid sample and the performance of the battery using the corresponding positive electrode mixture liquid are illuminated. By _combining them, a preferable range (acceptable range) of V _2MAX / V _1MAX can be defined. Furthermore, the stirring conditions employed when preparing the positive electrode mixture solution in the acceptable range (in this example, the predetermined stirring speed and the stirring time range corresponding to V _2MAX / V _1MAX in the _acceptable range) are determined from the next positive electrode. By applying it to the preparation of the composite material liquid, it is possible to efficiently prepare the acceptance-standard positive electrode composite liquid. In a preferable embodiment, for example, it can be set as a pass condition that V _2MAX / V _1MAX is in the range of about 0.2 to 20. The upper limit of the pass condition (the range of V _2MAX / V _1MAX ) may be 15, 10 or 5. Further, the lower limit of the pass condition may be 0.5 or 1. For example, it may be set as a passing condition that V _2MAX / V _1MAX is in a range of about 0.5 to 10 (typically 1 to 5). When the maximum frequency is not detected as a clear peak in the first particle size range or the second particle size range (when only an ascending curve or a descending curve appears in the corresponding range), the maximum frequency is the corresponding particle size range. The maximum frequency (ie, the maximum frequency of the rising curve in the range (ie, the end point of the curve in the range) or the maximum frequency of the falling curve (ie, the starting point of the curve in the range)) Shall be adopted.

  The zeta potential of a particle dispersed in a liquid is defined as ions existing in the vicinity of the particle, with the potential in a region not affected by the surface charge of the particle (an electrically neutral region sufficiently away from the particle) being zero. It is defined as the potential at the boundary interface (the boundary surface that can move with the ions; slip surface) that affects the surface.

  The measurement of the zeta potential of the electrode mixture solution may be performed using, for example, a commercially available zeta potential measuring instrument. For example, Dispersion Technology (USA) (manufactured in Japan: Nippon Luft), model “DT-1200” or an equivalent thereof can be preferably used. Typically, the cell containing the positive electrode mixture liquid sample is expanded with an optical microscope, a direct current is applied, the conductive material particles to be measured are selected, and the electrophoretic mobility (movement speed) of the conductive material particles Measure. This measurement is performed on 5 to 6 different conductive material particles, and the arithmetic average of the moving speed is obtained. The obtained arithmetic average value is converted into a zeta potential by the Henry equation. The measurement conditions may be set as appropriate and can be converted to the desired measurement conditions even if the conditions are somewhat different, but it is typically preferable to carry out at a room temperature of about 25 ° C. In the technology disclosed herein, the zeta potential may be measured immediately after the preparation of the positive electrode mixture solution, or may be performed after 1 to 3 days have elapsed since the preparation.

  When the zeta potential is adopted as an index for grasping the dispersion state of the positive electrode mixture liquid, it can be set as a passing condition that the zeta potential is in a predetermined range. The acceptable range is determined based on the correlation between the zeta potential measured for a plurality of positive electrode mixture liquid samples with different preparation conditions (stirring time, speed, etc.) and the performance of the battery using the corresponding positive electrode mixture liquid. be able to. For example, by preparing positive electrode mixture liquids with different stirring times at a predetermined speed, and comparing the zeta potential of each positive electrode mixture liquid sample with the performance of the battery using the corresponding positive electrode mixture liquid A preferable range (acceptable range) of the zeta potential can be defined. Furthermore, by applying the stirring conditions employed in the preparation of the positive electrode mixture liquid in the acceptable range to the subsequent preparation of the positive electrode mixture liquid, an acceptable reference positive electrode mixture liquid can be efficiently prepared. In a preferred embodiment, for example, it can be set as a pass condition that the zeta potential is in the range of about −10 mV to −5 mV.

  The conductivity of the electrode mixture solution can be measured using, for example, a commercially available conductivity meter (for example, an electrode type can be preferably used). Typically, a standard solution with a known conductivity is placed in a cell with a fixed volume, the resistance value is measured, the cell constant is obtained, and then the resistance value of the positive electrode mixture liquid to be measured is the same volume cell. The conductivity can be calculated by measuring using. For measuring the resistance value, it is preferable to employ a double cylindrical tube current measurement, an AC impedance method, or the like. For example, at a room temperature of about 25 ° C., a sine wave having a frequency of about 1 to 10 Hz may be applied in a double cylindrical tube current measurement, and an alternating current having a frequency of about 1 kHz may be applied in an AC impedance method.

When the conductivity is adopted as an index for grasping the dispersion state of the positive electrode mixture liquid, it can be set as a passing condition that the conductivity is in a predetermined range. The acceptable range is determined based on the correlation between the conductivity measured for a plurality of positive electrode mixture liquid samples with different preparation conditions (stirring time, speed, etc.) and the performance of the battery using the corresponding positive electrode mixture liquid. be able to. For example, by preparing a positive electrode mixture liquid with different stirring times at a predetermined speed, and comparing the conductivity of each positive electrode mixture liquid sample with the performance of the battery using the corresponding positive electrode mixture liquid The preferable range (acceptable range) of electrical conductivity can be specified. Furthermore, the acceptance-standard positive electrode mixture liquid can be efficiently prepared by applying the stirring conditions employed in the preparation of the positive electrode mixture liquid in the acceptable range to the subsequent preparation of the positive electrode mixture liquid. In a preferred embodiment, for example, it can be set as a pass condition that the conductivity is in the range of about 1 × 10 ^{−4 to} 5 × 10 ⁻⁴ S / m.

  Hereinafter, with reference to the drawings, for a lithium ion secondary battery to which the technology disclosed herein is applied, a lithium ion secondary battery in which an electrode body and a non-aqueous electrolyte are housed in a rectangular battery case The battery will be described in more detail as an example, but the application target of the present invention is not intended to be limited to such an embodiment. That is, the shape of the lithium ion secondary battery and other non-aqueous secondary batteries according to the present invention is not particularly limited, and the battery case, electrode body, etc. are made of materials, shapes, sizes, etc. according to the application and capacity. It can be selected appropriately. For example, the shape of the battery case may be a rectangular parallelepiped shape, a flat shape, a cylindrical shape, or the like. In addition, in the following drawings, the same code | symbol is attached | subjected to the member and site | part which show | plays the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships.

  As shown in FIGS. 1 and 2, in the lithium ion secondary battery 100 according to the present embodiment, the wound electrode body 20 together with the nonaqueous electrolytic solution 90 has a flat box shape corresponding to the shape of the electrode body 20. The opening 12 of the case 10 having a configuration accommodated in the battery case 10 is closed by a lid 14. The lid body 14 is provided with a positive terminal 38 and a negative terminal 48 for external connection so that a part of the terminals protrudes to the surface side of the lid body 14.

  The electrode body 20 includes a positive electrode sheet 30 in which a positive electrode active material layer 34 is formed on the surface of a long sheet-like positive electrode current collector 32, and a negative electrode active material layer on the surface of a long sheet-like negative electrode current collector 42. The negative electrode sheet 40 on which the electrode 44 is formed is rolled up with two long sheet-like separators 50, and the obtained wound body is pressed from the side direction and ablated to form a flat shape. Has been. In the battery 100 having such a configuration, for example, the electrode body 20 is accommodated in the opening 10 of the case 10, the lid body 14 is attached to the opening 12 of the case 10, and then the electrolyte provided in the lid body 14. It can be constructed by injecting an electrolytic solution 90 from an injection hole (not shown) and then closing the injection hole.

  The positive electrode current collector 32 is exposed at one end portion along the longitudinal direction of the positive electrode sheet 30. That is, the positive electrode active material layer 34 is not formed at the end, or is removed after the formation. Similarly, the negative electrode current collector 42 is exposed at one end portion along the longitudinal direction of the wound negative electrode sheet 40. Then, the positive electrode terminal 38 is joined to the exposed end portion of the positive electrode current collector 32, and the negative electrode terminal 48 is joined to the exposed end portion of the negative electrode current collector 42, respectively. The positive electrode sheet 30 or the negative electrode sheet 40 is electrically connected. The positive and negative terminals 38 and 48 and the positive and negative current collectors 32 and 42 can be joined by, for example, ultrasonic welding, resistance welding, or the like.

  The positive electrode active material layer 34 can be preferably produced, for example, by applying a positive electrode mixture liquid satisfying a preset acceptance condition to the positive electrode current collector 32 and drying the mixture liquid.

  For the positive electrode current collector 32, a conductive member made of a metal having good conductivity is preferably used. For example, aluminum or an alloy containing aluminum as a main component can be used. The shape of the positive electrode current collector 32 may vary depending on the shape of the lithium ion secondary battery, and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. . In the lithium ion secondary battery 100 including the wound electrode body 20 as in the present embodiment, for example, an aluminum sheet having a thickness of about 10 μm to 30 μm can be preferably used as the positive electrode current collector 32.

  The negative electrode active material layer 44 is made of, for example, a negative electrode current collector made of a paste or slurry composition (negative electrode mixture liquid) in which a negative electrode active material is dispersed in an appropriate solvent together with a binder or the like. It can preferably be prepared by applying to 42 and drying the composition.

As the negative electrode active material, one type or two or more types of materials conventionally used in lithium ion secondary batteries can be used without any particular limitation. For example, a carbon particle is mentioned as a suitable negative electrode active material. A particulate carbon material (carbon particles) containing a graphite structure (layered structure) at least partially is preferably used. Any carbon material of a so-called graphitic material (graphite), non-graphitizable carbon material (hard carbon), easily graphitized carbon material (soft carbon), or a combination of these materials is preferably used. obtain.
The amount of the negative electrode active material contained in the negative electrode active material layer is not particularly limited, and is preferably about 90 to 99% by mass, more preferably about 95 to 99% by mass.

  As the binder, the same positive electrode as that described above can be used alone or in combination of two or more. What is necessary is just to select the addition amount of a binder suitably according to the kind and quantity of a negative electrode active material.

  As the negative electrode current collector 42, a conductive member made of a metal having good conductivity is preferably used. For example, copper or an alloy containing copper as a main component can be used. In addition, the shape of the negative electrode current collector 42 may vary depending on the shape of the lithium ion secondary battery and the like, and thus is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. possible. In the lithium ion secondary battery 100 including the wound electrode body 20 as in the present embodiment, for example, a copper sheet having a thickness of about 5 μm to 30 μm can be preferably used as the negative electrode current collector 42.

Moreover, as the separator 50 used by overlapping with the positive electrode sheet 30 and the negative electrode sheet 40, various separators used for a general lithium ion secondary battery can be used without any particular limitation. For example, a porous film made of a polyolefin resin such as polyethylene and polypropylene can be suitably used. The film may be a single layer or a multilayer. A resin film provided with an inorganic filler layer containing one or more ceramic particles such as titania (titanium oxide; TiO ₂ ), alumina, silica, magnesia, zirconia, zinc oxide, iron oxide, ceria, and yttria. May be used. The thickness of the separator may be selected as appropriate.

The nonaqueous electrolytic solution 90 can be prepared by dissolving a suitable electrolyte in a nonaqueous solvent. As the electrolyte, an electrolyte used for a general lithium ion secondary battery can be used without particular limitation. For example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiI, etc. are selected. One or more lithium salts can be used. The concentration of the electrolyte in the electrolytic solution is not particularly limited, and can be, for example, equivalent to the concentration of the electrolytic solution used in a conventional lithium ion secondary battery. Usually, a nonaqueous electrolytic solution containing a supporting electrolyte at a concentration of about 0.1 mol / L to 5 mol / L (for example, about 0.8 mol / L to 1.5 mol / L) can be preferably used.

  As the organic solvent (nonaqueous solvent) used for the nonaqueous electrolytic solution 90, aprotic solvents such as carbonates, esters, ethers, nitriles, sulfones, and lactones can be preferably used. For example, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane , Tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, 1,3-dioxolane, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, acetonitrile, propionitrile, nitromethane, N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, γ-butyrolactone (BL), etc. The organic solvents generally used for lithium ion secondary batteries can be used alone or in combination of two or more.

  The non-aqueous secondary battery (typically lithium ion secondary battery) disclosed here can be used as a secondary battery for various applications. For example, as shown in FIG. 3, any non-aqueous secondary battery 100 disclosed herein can be suitably used as a power source for a vehicle driving motor (electric motor) mounted on a vehicle 1 such as an automobile. it can. Although the kind of vehicle 1 is not specifically limited, Typically, they are a hybrid vehicle, an electric vehicle, a fuel cell vehicle, etc. Such non-aqueous secondary battery 100 may be used alone, or may be used in the form of an assembled battery that is connected in series and / or in parallel.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to the specific examples.

<Example 1>
Acetylene black (AB) having a number average particle diameter of 0.035 μm measured by an optical microscope (made by OLYMPUS, model “BH-2”) (DENKA BLACK (registered trademark) powder product of Denki Kagaku Kogyo Co., Ltd.) Material) and powdered PVDF (binder) are mixed with N-methyl-2-pyrrolidone (NMP) so that the mass ratio thereof is 8: 2, and a stirrer manufactured by Asada Tekko Co., Ltd. Conductive material dispersion for positive electrode having a solid content concentration (NV) of 20% by stirring and mixing for 60 minutes under the condition (first stirring condition) at a peripheral speed of 10 m / sec using a product name Pico Glen Mill, model “PCM-L” A liquid was prepared. LiNi _1/3 Mn _{/ 3} Co _/ 3O ₂ (active material particles having a number average particle diameter of 10 μm based on the above-mentioned optical microscope observation) as a positive electrode active material was added to this conductive material dispersion liquid 10 parts of the dispersion liquid. 90 parts are added per (solid content basis), and a stirrer manufactured by Primics Co., Ltd. K. Using a Hibis Disper mix (trademark), model “3D-5”, stirring and mixing for 20 minutes under conditions (second stirring conditions) of planetary mixer: 40 rpm and homodisper: 2500 rpm, a positive electrode mixture solution of NV55% Got. V _1MAX measured according to the dynamic light scattering method for this positive electrode mixture solution was 1%, and V _2MAX was 20%. This positive electrode mixture solution was applied to both sides of a 15 μm thick long aluminum foil, dried and rolled, and the total thickness (the total thickness of both positive electrode active material layers and current collector foil) was 180 μm. A positive electrode sheet having an active material layer density of 3.2 g / cm ³ was prepared.

Natural graphite particles, SBR, and CMC were mixed with ion-exchanged water so that the mass ratio thereof was 98: 1: 1, to obtain a negative electrode mixture solution with an NV of 50%. This was applied to both sides of a long copper foil having a thickness of 10 μm, dried and rolled to prepare a negative electrode sheet having a total thickness of 170 μm and a negative electrode active material layer density of 1.5 g / cm ³ .
A non-aqueous electrolyte was prepared by dissolving LiPF _{6 in} a mixed solvent of EC / EMC = 3/7 (volume ratio) to a concentration of 1M.
The positive electrode sheet and the negative electrode sheet were laminated together with two long porous polyethylene sheets having a thickness of 21 μm, and the laminate was wound in the longitudinal direction to obtain an electrode body. The obtained wound electrode body is housed in a cylindrical container (cylindrical type having a diameter of 18 mm and a height of 65 mm) together with the non-aqueous electrolyte, the container is sealed, and the 18650 type battery 200 having a design capacity of 2000 mAh. (FIG. 4) was constructed.

<Example 2>
A positive electrode mixture solution having 1% V _1MAX , 15% V _2MAX , and 55% NV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 90 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 3>
A positive electrode mixture solution having 5% V _1MAX , 10% V _{2MAX and} 55% NV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 120 minutes. A 18650 type battery was constructed in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 4>
A positive electrode mixture solution having 3% V _1MAX , 3% V _{2MAX and} 55% NV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 240 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.

<Example 5>
A positive electrode mixture solution having 5% V _1MAX , ₁ % V _{2MAX and} 55% NV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 480 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 6>
V _1MAX and V _2MAX are both 0 as in Example 1 except that carbon black powder (product number “SRF-LS” manufactured by Tokai Carbon Co., Ltd.) having an arithmetic average particle size of about 100 μm was used as the conductive material. % (Not detected on the chart) and a positive electrode mixture solution of NV55% were obtained. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.

<Example 7>
A positive electrode mixture solution having V _1MAX of 1%, _V2MAX of 23% and NV of 55% was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 45 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 8>
A positive electrode mixture solution with V _1MAX of 0.5%, V _2MAX of 25% and NV of 55% was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 30 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 9>
A positive electrode mixture solution with V _1MAX of 11%, V _2MAX of 2% and NV of 55% was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 960 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.

[Measurement of particle size distribution]
For each positive electrode mixture liquid sample according to Examples 1 to 9, using a dynamic light scattering method particle size distribution measuring device (model “UPA-150EX”, model “UPA-150EX”) at a temperature of 20 ° C., photon The particle size distribution was measured according to the principle of the correlation method. Maximum frequency in the range of particle sizes 0.1μm~1.0μm a (%) _{V 1MAX,} the maximum frequency of the range of particle sizes 1.0μm~4.0μm (%) as a _{V 2MAX,} seeking V 2MAX _{/ V 1MAX} It was. The particle size distribution charts according to Examples 1 to 9 are shown in FIGS.

The following measurements and evaluation tests were performed on each battery. The results are shown in Table 1 together with V _2MAX / V _1MAX .
[Measurement of 0.2C discharge capacity]
Each battery was kept at a constant current until the voltage between both terminals reached 4.2 V at a temperature of 20 ° C. and a rate of 0.7 C (1400 mA) (1 C represents a current value that can be fully charged and discharged in 1 hour). (CC) charging was performed, and constant voltage (CV) charging was performed until the current value reached 100 mA at the voltage value. Next, CC discharge was performed at a rate of 0.2 C (400 mA) until the voltage between both terminals reached 3.0 V, and the discharge capacity at that time was measured as a 0.2 C discharge capacity.

[Measurement of 3C discharge capacity]
Each battery was CC charged at a temperature of 20 ° C. at a rate of 0.7 C until the voltage between both terminals reached 4.2 V, and CV charged at the voltage value until the current value reached 100 mA. Next, after each battery was held at a temperature of −15 ° C. for 30 minutes, CC discharge was performed at the same temperature at a rate of 3C (6000 mA) until the voltage between both terminals became 3.0 V, and the discharge capacity at that time was 3C. The discharge capacity was measured. The percentage (%) of the 3C discharge capacity with respect to the 0.2C discharge capacity was calculated as the capacity ratio.

[Evaluation of cycle characteristics]
One charge / discharge operation for charging each battery at a temperature of 40 ° C. at a rate of 1 C until the voltage between both terminals reaches 4.2 V and for discharging at a rate of 1 C from 4.2 V to 3.0 V This was repeated 500 cycles as a cycle. The discharge capacities at the first cycle and the 500th cycle were measured as an initial capacity and a final capacity, respectively. The percentage of the final capacity with respect to the initial capacity was determined as 1C capacity maintenance rate (%).

As shown in Table 1, the batteries of Examples 1 to 9 all had a measured discharge capacity of 2000 mAh or more and 2010 mAh or less under a mild discharge condition (20 ° C., 0.2 C discharge). And a stable (small variation) performance regardless of the difference in the stirring conditions (here, the stirring time in the first stirring condition). However, under the severer conditions of low temperature rapid discharge (−15 ° C., 3C discharge), the batteries of Examples 1 to 5 in which V _2MAX / V _1MAX is in the range of 0.2 to 20 and examples outside this range There was a significant difference in performance between 7 and 9 batteries. More specifically, the batteries of Examples 1 to 5 in which V _2MAX / V _1MAX is in the range of 0.2 to 20 have a capacity ratio of 90% or more, even under the above mild discharge conditions even under such severe use conditions. It showed good performance that did not change much. On the other hand, the batteries of Example 7 and Example 8 in which V _2MAX / V _1MAX exceeded 20 and the battery of Example 9 in which V _2MAX / V _1MAX was less than 0.2 had a 3C discharge capacity higher than the 0.2C discharge capacity. It was 15% lower. _{Also, V 1MAX} and _{V 2MAX} was detected neither (i.e., 0.1Myuemu～4myuemu range of frequencies was almost zero in the particle size distribution of the used were conductive material) of Example 6 batteries, 3C discharge The capacity was reduced to a quarter of the 0.2C discharge capacity.

  Regarding the capacity retention calculated in the charge / discharge cycle test at 1C, the batteries of Examples 1 to 5 all showed excellent cycle characteristics exceeding 90%. On the other hand, in all the batteries of Examples 7 to 9, the discharge capacity after the cycle decreased from 18% from the initial capacity to a maximum of 35%. The battery of Example 6 had a discharge capacity after cycling that was not one third of the initial capacity, and caused a significant decrease in capacity even under moderate usage conditions.

These results are combined with the same results according to Examples 10 to 19 below, and even if the battery has little difference in performance under mild use conditions, the performance varies significantly under severe use conditions (for example, This shows that variation due to the difference in stirring conditions may occur. Moreover, the positive-electrode mixture solution of Example _{1~9, V} 2MAX _/ V _1MAX is set as pass condition to be in the range of 0.2 to 20 (e.g., only the pass condition is satisfied positive-electrode mixture solution Sending to the next process (typically, applying the positive electrode mixture liquid to the positive electrode current collector) is significant in producing a battery with little performance difference (performance variation) even under more severe conditions. It shows that it is.

<Example 10>
A positive electrode mixture solution having a zeta potential of −7.5 mV of the conductive material measured by the method described later was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 120 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 11>
A positive electrode mixture solution having a zeta potential of −5.0 mV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 60 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 12>
A positive electrode mixture solution having a zeta potential of -10.0 mV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 480 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.

<Example 13>
A positive electrode mixture solution having a zeta potential of −3.5 mV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 30 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 14>
A positive electrode mixture solution having a zeta potential of -12.0 mV was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 960 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.

[Measurement of zeta potential]
For each positive electrode mixture liquid sample according to Examples 10 to 14, at a temperature of 25 ° C., a zeta potential measurement device (available from Dispersion Technology (USA) (Japan handling: Nippon Luft)), model “DT-1200”) The zeta potential (mV) was determined by the colloid oscillating current method.

  About each battery which concerns on Examples 10-14, 0.2C discharge capacity, 3C discharge capacity, capacity | capacitance ratio, and capacity | capacitance maintenance factor were measured by the method similar to the above. The results are shown in Table 2 together with the zeta potential of the conductive material.

  As shown in Table 2, all of the batteries of Examples 10 to 14 are suitable for the set capacity with a measured 0.2 C discharge capacity of 2000 mAh to 2010 mAh under mild discharge conditions (20 ° C., 0.2 C discharge). And showed stable (small variation) performance regardless of the stirring conditions. However, under low temperature rapid discharge conditions (−15 ° C., 3C discharge), the batteries of Examples 10 to 12 in which the zeta potential is in the range of −10 mV to −5 mV and the batteries of Examples 13 and 14 outside this range are used. A significant difference in performance appeared. More specifically, the batteries of Examples 10 to 12 whose zeta potential is in the range of −10 mV to −5 mV have a capacity ratio exceeding 90%, and even under such severe use conditions, the batteries are not so different from those under the mild discharge conditions. It showed good performance. On the other hand, in the battery of Example 13 having a zeta potential greater than −5 mV, the 3C discharge capacity decreased nearly 20% from the 0.2C discharge capacity. Further, in the battery of Example 14 whose zeta potential was smaller than −10 mV, the 3C discharge capacity decreased to 3/4 or less of the 0.2C discharge capacity. Regarding the capacity retention calculated in the charge / discharge cycle test at 1C, the batteries of Examples 10 to 12 all showed excellent cycle characteristics exceeding 90%. On the other hand, in each of the batteries of Examples 13 and 14, the discharge capacity after the cycle decreased by 15% or more from the initial capacity.

These results show that the positive electrode mixture liquids according to these examples have a zeta potential in the range of −10 mV to −5 mV as a pass condition, and performance differences (performance variations) even under more severe conditions. This indicates that it is significant in manufacturing a battery with a small amount of.
For the positive electrode mixture liquid samples according to Examples 10 and 13, the particle size distribution was measured in the same manner as in the positive electrode mixture liquid samples according to Examples 1 to 9, and V _2MAX / V _1MAX was similarly obtained. As a result, it was confirmed that the sample according to Example 10 had V _2MAX / V _{1MAX in} the range of 0.5 to 10 (more specifically, 1 to 5). On the other hand, it was confirmed that the sample according to Example 13 did not satisfy the pass condition of V _2MAX / V _1MAX = 0.2-20.

<Example 15>
A positive electrode mixture solution having an electric conductivity of 3 × 10 ⁻⁴ S / m was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 120 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 16>
A positive electrode mixture solution having an electric conductivity of 1 × 10 ⁻⁴ S / m was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 480 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 17>
A positive electrode mixture solution having an electric conductivity of 5 × 10 ⁻⁴ S / m was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 60 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.

<Example 18>
A positive electrode mixture solution having an electric conductivity of 0.5 × 10 ⁻⁴ S / m was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 960 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.
<Example 19>
A positive electrode mixture solution having an electric conductivity of 7 × 10 ⁻⁴ S / m was obtained in the same manner as in Example 1 except that the stirring time under the first stirring condition was 30 minutes. An 18650 type battery was obtained in the same manner as in Example 1 except that this positive electrode mixture solution was used.

[conductivity]
For each positive electrode mixture liquid sample according to Examples 15 to 19, at a temperature of 25 ° C., a conductivity meter (conductivity meter available from Nippon Luft Co., model “DT-700”) was used, and a double cylindrical tube current was used. The conductivity (S / m) was determined from the resistance value (mΩ) measured by measurement (Sine wave having a frequency of 1 to 10 Hz).

  About each battery which concerns on Examples 15-19, 0.2C discharge capacity, 3C discharge capacity, a capacity | capacitance ratio, and a capacity | capacitance maintenance factor were measured by the method similar to the above. The results are shown in Table 3 together with the zeta potential of the conductive material.

As shown in Table 3, all of the batteries of Examples 15 to 19 meet the set capacity of 2000 mAh or more and 2010 mAh in the measured 0.2C discharge capacity under mild discharge conditions (20 ° C., 0.2C discharge). It was a value, and stable (small variation) performance was exhibited regardless of the difference in the stirring conditions (here, the stirring time in the second stirring condition). However, in low temperature rapid discharge conditions (−15 ° C., 3C discharge), the conductivity measured for the positive electrode mixture solution is in the range of 1 × 10 ^{−4 to} 5 × 10 ⁻⁴ S / m. There was a significant difference in performance between the battery and the batteries of Examples 18 and 19 outside the above range. More specifically, the batteries of Examples 15 to 17 having a conductivity in the range of 1 × 10 ^{−4 to} 5 × 10 ⁻⁴ S / m have a capacity ratio exceeding 90%, and the above-mentioned mild conditions It showed good performance that was not so different from that under the various discharge conditions. On the other hand, the battery of Example 18 having a conductivity lower than 1 × 10 ⁻⁴ S / m and the battery of Example 19 having a conductivity higher than 5 × 10 ⁻⁴ S / m have a 3C discharge capacity of 0.2C discharge capacity. 20% or more. Regarding the capacity retention calculated in the charge / discharge cycle test at 1C, the batteries of Examples 15 to 17 all showed excellent cycle characteristics exceeding 90%. On the other hand, in both the batteries of Examples 18 and 19, the discharge capacity after the cycle was reduced by about 20% or more from the initial capacity.

These results show that the positive electrode mixture liquids according to these examples are more stringent under the condition that the conductivity is in the range of 1 × 10 ^{−4 to} 5 × 10 ⁻⁴ S / m. This also shows that it is significant in manufacturing a battery with little performance difference (performance variation).
For the positive electrode mixture liquid samples according to Examples 15, 18, and 19, the particle size distribution was measured in the same manner as the positive electrode mixture liquid samples according to Examples 1 to 9, and V _2MAX / V _1MAX was obtained in the same manner. As a result, it was confirmed that the sample according to Example 15 had V _2MAX / V _{1MAX in} the range of 0.5 to 10 (more specifically, 1 to 5). On the other hand, it was confirmed that the samples according to Example 18 and Example 19 did not satisfy the pass condition of V _2MAX / V _1MAX = 0.2-20.
For the positive electrode mixture liquid samples according to Examples 15, 16, and 19, the zeta potential (mV) was measured in the same manner as the positive electrode mixture liquid samples according to Examples 10 to 14. As a result, it was confirmed that the samples according to Examples 15 and 16 each had a zeta potential in the range of −10 mV to −5 mV. On the other hand, it was confirmed that the sample according to Example 19 did not satisfy the pass condition of zeta potential = −10 mV to −5 mV.

  As mentioned above, although this invention was demonstrated in detail, the said embodiment and Example are only illustrations and what changed and changed the above-mentioned specific example is contained in the invention disclosed here.

DESCRIPTION OF SYMBOLS 1 Vehicle 20 Winding electrode body 30 Positive electrode sheet 32 Positive electrode current collector 34 Positive electrode active material layer 38 Positive electrode terminal 40 Negative electrode sheet 42 Negative electrode current collector 44 Negative electrode active material layer 48 Negative electrode terminal 50 Separator 90 Nonaqueous electrolyte (nonaqueous electrolyte) )
100 Nonaqueous secondary battery 200 18650 type secondary battery

Claims (8)

A method of manufacturing a non-aqueous secondary battery comprising:
(A) preparing an electrode body provided with an active material layer in which at least one electrode includes active material particles and conductive material particles; and
(B) A step of housing the electrode body and the non-aqueous electrolyte in a battery container to construct a non-aqueous secondary battery;
Including
The step (A) is:
(I) preparing an electrode mixture liquid in which active material particles and conductive material particles are dispersed in a liquid phase for forming the at least one electrode; and
(Ii) grasping the dispersion state of the electrode mixture liquid, wherein the dispersion state is grasped by measuring at least one of a particle size distribution, a zeta potential, and an electrical conductivity of the electrode mixture liquid. Done by
(Iii) When the grasped dispersion state satisfies a preset acceptance condition, the electrode mixture solution is sent to the next step, and when the acceptance condition is not satisfied, the electrode mixture solution is removed from the next step. That; and
(Iv) forming the active material layer using the electrode mixture liquid sent to the next step;
A method for producing a non-aqueous secondary battery.   The method according to claim 1, wherein the total amount of solids contained in the electrode mixture solution is 100% by mass, and the content of the conductive material particles is 0.5 to 10% by mass.   The method according to claim 1, wherein the average size of the active material particles is 5 μm to 20 μm as an arithmetic average value of the diameters of the plurality of active material particles measured by an optical microscope. The conductive material particles are carbon particles having a structure in which a plurality of primary particles are linked,
The average size of the carbon particles is 0.1 μm to 4.0 μm as an arithmetic average value of the lengths of the plurality of carbon particles measured by an optical microscope. Method. The particle size distribution is measured by a dynamic light scattering method,
In the measured particle size distribution, V _1MAX is the maximum frequency (%) in the range of 0.1 μm or more and less than 1.0 μm, and V _2MAX is the maximum frequency (%) in the range of 1.0 μm or more and less than 4.0 μm. and the pass condition that the ratio of _{V 2MAX (V 2MAX / V 1MAX} ) is within a predetermined numerical range for _1MAX, the method according to any one of claims 1 to 4. The method according to claim 5, wherein the passing condition is that V _2MAX / V _1MAX is in a range of 0.2 to 20.   The method according to claim 1, wherein the pass condition is that the zeta potential is in the range of −5 mV to −10 mV. 5. The method according to claim 1, wherein the pass condition is that the conductivity is in a range of 1 × 10 ^{−4 to} 5 × 10 ⁻⁴ S / m.

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