Electrode binder composition, electrode slurry, electrode, non-aqueous secondary battery, and method for producing electrode

Abstract

An electrode binder composition comprising: an aqueous medium; a dispersible anionic polymer (P1) that has an anionic functional group and is dispersed in the aqueous medium; and a multivalent cationic material (C) that is capable of providing multivalent cations (c) in the aqueous medium.

Description

Electrode binder composition, electrode slurry, electrode, non-aqueous secondary battery, and method for manufacturing the electrode

[0001] This disclosure relates to an electrode binder composition, an electrode slurry, an electrode, a non-aqueous secondary battery, and a method for manufacturing an electrode.

[0002] Non-aqueous rechargeable batteries can be used repeatedly by recharging, and can also be made smaller and lighter. For these reasons, non-aqueous rechargeable batteries are widely used as power sources for notebook computers, mobile phones, power tools, electronic communication equipment, electric vehicles, and other devices.

[0003] Non-aqueous secondary batteries include a positive electrode containing a metal oxide or the like as an active material, a negative electrode containing a carbon material such as graphite as an active material, and an electrolyte. The positive electrode and the negative electrode each comprise a current collector and an electrode active material layer formed on the current collector. The electrode active material layer usually contains a binder along with the active material, and the binder binds the particles of the active material together, and the particles of the active material together with the current collector.

[0004] For example, Patent Document 1 describes an electrode for an electrochemical energy storage device, comprising an electrode active material and a crosslinking binder, wherein the crosslinking binder comprises a polymer electrolyte having carboxyl groups and polyphosphate, and the polymer electrolyte is crosslinked by a polyphosphate salt.

[0005] Patent Document 1: Japanese Unexamined Patent Publication No. 2024-27111

[0006] Non-patent document 1: Y. Tezuka, Y. Tsuchiya, and T. Shiomi, Carbohydr. Res. 291, 99-108 (1996)

[0007] Non-aqueous secondary batteries are known to have a reduced battery capacity when charge and discharge are repeated. Therefore, a small reduction in capacity when charge and discharge are repeated in non-aqueous secondary batteries is one of the important characteristics. In view of the above circumstances, an object of one embodiment of the present disclosure is to provide an electrode binder composition, an electrode slurry, an electrode, and a method for manufacturing an electrode capable of obtaining a non-aqueous secondary battery with a small reduction in capacity when charge and discharge are repeated. Another object of one embodiment of the present disclosure is to provide a non-aqueous secondary battery with a small reduction in capacity when charge and discharge are repeated.

[0008] The present disclosure includes the following aspects. <1> An electrode binder composition comprising an aqueous medium, a dispersible anionic polymer (P1) having an anionic functional group and dispersed in the aqueous medium, and a polyvalent cationic substance (C) capable of forming a polyvalent cation (c) in the aqueous medium. <2> The electrode binder composition according to <1>, wherein the amount of anions A per gram of the dispersible anionic polymer (P1) is 0.30 mmol / g or more. <3> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the dispersible anionic polymer (P1) is 0.050 or more and 5.0 or less in the electrode binder composition according to <1> or <2>. <4> The electrode binder composition according to any one of <1> to <3>, wherein the polyvalent cationic substance (C) contains at least one selected from the group consisting of metals and metal compounds. <5> The electrode binder composition according to any one of <1> to <4>, further comprising a soluble anionic polymer (P2) having an anionic functional group and dissolved in the aqueous medium. <6> The electrode binder composition according to <5>, wherein the amount of anions A per gram of the soluble anionic polymer (P2) is 1.0 mmol / g or more. <7> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the soluble anionic polymer (P2) is 0.050 or more and 5.0 or less in the electrode binder composition according to <5>. Ｐ１ is 0.30 mmol / g or more in the electrode binder composition according to <1>. <3> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the dispersible anionic polymer (P1) Ｐ１ in the electrode binder composition according to <1> or <2>. <4> The polyvalent cationic substance (C) contains at least one selected from the group consisting of metals and metal compounds in the electrode binder composition according to any one of <1> to <3>. <5> The electrode binder composition according to any one of <1> to <4> further comprises a soluble anionic polymer (P2) having an anionic functional group and dissolved in the aqueous medium. <6> The amount of anions A per gram of the soluble anionic polymer (P2) Ｃ in the electrode binder composition according to <5>. <7> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the soluble anionic polymer (P2) Ｃ in the electrode binder composition according to <5>. <7> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the soluble anionic polymer (P2) Ｐ１ is 0.050 or more and 5.0 or less in the electrode binder composition according to <1> or <2>. <4> The polyvalent cationic substance (C) contains at least one selected from the group consisting of metals and metal compounds in the electrode binder composition according to any one of <1> to <3>. <5> The electrode binder composition according to any one of <1> to <4> further comprises a soluble anionic polymer (P2) having an anionic functional group and dissolved in the aqueous medium. <6> The amount of anions A per gram of the soluble anionic polymer (P2) Ｐ２ is 1.0 mmol / g or more in the electrode binder composition according to <5>. <7> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the soluble anionic polymer (P2) Ｐ２ in the electrode binder composition according to <5>. <7> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the soluble anionic polymer (P2) Ｃ in the electrode binder composition according to <5>. <7> The ratio X of the amount of cations X of the polyvalent cationic substance (C) to the amount of anions Y of the soluble anionic polymer (P2) Ｃ is 0.050 or more and 5.0 or less in the electrode binder composition according to <5>. Ｐ２The electrode binder composition according to <5> or <6>, wherein the ratio is 0.010 or more and 3.0 or less. <8> An electrode slurry comprising: an aqueous medium; an electrode active material; a dispersible anionic polymer (P1) having an anionic functional group and dispersed in the aqueous medium; and a polyvalent cationic substance (C) capable of forming a polyvalent cation (c) in the aqueous medium. <9> The electrode slurry according to <8>, further comprising a soluble anionic polymer (P2) having an anionic functional group and dissolved in the aqueous medium. <10> An electrode comprising a current collector and an electrode active material layer, wherein the electrode active material layer comprises: an electrode active material; a dispersible anionic polymer (P1) having anionic functional group and dispersed in an aqueous medium; and a polyvalent cation (c). <11> The electrode according to <10>, further comprising a soluble anionic polymer (P2) having anionic functional group and dissolved in an aqueous medium. A non-aqueous secondary battery comprising the electrodes described in <12>, <10>, or <11>. <13> A method for manufacturing an electrode, comprising: a mixing step of mixing an electrode active material, an aqueous medium, a dispersible anionic polymer (P1) having an anionic functional group and dispersed in the aqueous medium, and a polyvalent cationic substance (C) capable of forming a polyvalent cation (c) in the aqueous medium to obtain an electrode slurry; a coating step of applying the electrode slurry to a current collector; and a drying step of removing the aqueous medium from the electrode slurry applied to the current collector. <14> The method for manufacturing an electrode according to <13>, wherein in the mixing step, a soluble anionic polymer (P2) having anionic functional group and dissolved in the aqueous medium is further mixed.

[0009] According to one embodiment of the present disclosure, an electrode binder composition, electrode slurry, electrode, and method for manufacturing the electrode are provided, which can produce a non-aqueous secondary battery with minimal capacity degradation when repeatedly charged and discharged. Furthermore, according to one embodiment of the present disclosure, a non-aqueous secondary battery with minimal capacity degradation when repeatedly charged and discharged is provided.

[0010] The embodiments of this disclosure will be described in detail below. However, this disclosure is not limited to the embodiments described below. In the embodiments described below, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit this disclosure. For example, within the scope of this disclosure, numbers, quantities, positions, ratios, materials, configurations, types, order, etc., can be added, omitted, substituted, or modified without departing from the spirit thereof.

[0011] In this disclosure, the numerical range indicated using "~" includes the numbers before and after "~" as the minimum and maximum values, respectively.

[0012] In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0013] In this disclosure, each component may contain multiple types of the corresponding substance. When multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified.

[0014] In this disclosure, the term "layer" includes cases where, when observing the region in which the layer exists, it is formed not only over the entire region but also over only a portion of the region.

[0015] In this disclosure, "(meth)acrylic" is a general term for acrylic and methacrylic, "(meth)acrylate" is a general term for acrylate and methacrylate, and "(meth)acryloyl group" is a general term for acryloyl group and methacrylicloyl group.

[0016] In this disclosure, "ethylenically unsaturated bond" refers to an ethylenically unsaturated bond that is radically polymerizable unless otherwise specified. Furthermore, in this disclosure, "ethylenically unsaturated compound" refers to a compound having an ethylenically unsaturated bond.

[0017] In this disclosure, taking a polymer having structural unit A derived from compound A having an ethylenically unsaturated bond as an example, the chemical structure of the portion of structural unit A of the polymer other than the portion corresponding to the ethylenically unsaturated bond of compound A (i.e., the portion contributing to the polymerization of compound A) is the same as the chemical structure of the portion of compound A other than the ethylenically unsaturated bond before polymerization. For example, a structural unit derived from styrene is "-CH" in the polymer. ２ CH(C) ６ H ５ It has the structure (phenyl group).

[0018] In this disclosure, a monomer corresponding to a structural unit in a polymer refers to a compound in which the bond between the two carbon atoms forming the main chain of the polymer in that structural unit is replaced with an ethylenically unsaturated bond and separated from other structural units.

[0019] Furthermore, if the structure of parts of the polymer other than the main chain structure corresponding to the ethylenically unsaturated bond (e.g., functional groups such as carboxyl groups) changes due to chemical reactions, the structural units are classified based on the chemical structure after the change. For example, if vinyl acetate is polymerized and then saponified, this structural unit is not a structural unit derived from vinyl acetate, but rather a structural unit derived from vinyl alcohol. For example, if a monomer having an ionic functional group is polymerized and then ion exchange is performed, the structural units are classified based on the chemical structure after ion exchange. Specifically, for example, if sodium acrylate is polymerized and then the corresponding structural unit is obtained by ion exchange, the structural unit is obtained as "-CH ２ When represented as "CH(COOH)-", this structural unit is referred to as a structural unit derived from acrylic acid, not from sodium acrylate.

[0020] In this disclosure, "non-volatile content" refers to components of the composition other than volatile components. More specifically, it refers to the components remaining after weighing 1 g of the composition onto a 5 cm diameter aluminum dish, drying it at 1 atmosphere (1013 hPa) in a drying oven at 105°C for 1 hour while circulating air. The composition may be in the form of a solution, dispersion, slurry, etc., but is not limited to these. The "non-volatile content concentration" of the composition is the mass ratio (mass%) of the non-volatile content remaining after drying under the above conditions, relative to the mass (1 g) of the composition before drying.

[0021] The dispersible anionic polymer (P1), polyvalent cationic substance (C), and soluble anionic polymer (P2) described below may be bonded to other molecules by electrostatic forces such as ionic bonds when included in electrode binder compositions, electrode slurries, electrodes, etc. In this case as well, the same names shall be used for the corresponding structures.

[0022] In the following explanation, the amount of anion or cation per mol of an anionic or cationic compound with an m-valence is calculated as m [mol].

[0023] <Electrode Binder Composition> One embodiment of this invention is an electrode binder composition comprising: an aqueous medium; a dispersible anionic polymer (P1) having anionic functional groups and dispersed in the aqueous medium; and a polyvalent cationic substance (C) capable of forming polyvalent cations (c) in the aqueous medium.

[0024] The electrode binder composition of this embodiment is preferably used for manufacturing electrodes for non-aqueous secondary batteries, and more preferably for manufacturing negative electrodes for non-aqueous secondary batteries.

[0025] The electrode binder composition according to this embodiment is used, for example, to form an electrode active material layer containing an electrode active material. When an electrode active material layer is formed using the electrode binder composition according to this embodiment, it is believed that bonds are formed between anionic compounds present in the electrode active material layer via polyvalent cations (c) derived from a polyvalent cationic substance (C). The bonds between anionic compounds via polyvalent cations (c) may be bonds between dispersible anionic polymers (P1) via polyvalent cations (c), or bonds between a dispersible anionic polymer (P1) and another anionic compound (for example, a soluble anionic polymer (P2)) via polyvalent cations (c). It is believed that the formation of the above-mentioned bonds strengthens the bonds between electrode active materials in the electrode active material layer. As a result, it is believed that electrodes made using the electrode binder composition according to this embodiment will have suppressed degradation of the electrode active material layer even after repeated charging and discharging, and that batteries with less capacity reduction can be obtained.

[0026] In this disclosure, an anionic functional group means a functional group that generates anions in an aqueous medium. The countercation of the anionic functional group is not particularly limited, but preferably includes at least one selected from the group consisting of hydrogen ions, alkali metal ions, and ammonium ions, more preferably includes one selected from the group consisting of hydrogen ions, sodium ions, and ammonium ions, and even more preferably includes one selected from the group consisting of hydrogen ions and sodium ions.

[0027] The electrode binder composition may further contain a soluble anionic polymer (P2) having anionic functional groups and soluble in an aqueous medium. In an electrode active material layer formed using an electrode binder composition containing the soluble anionic polymer (P2), it is thought that the soluble anionic polymer (P2) covers the surface of the electrode active material in a film-like manner, and the dispersible anionic polymer (P1) exists as particles between the electrode active materials. In this case, it is thought that a structure is formed in which the soluble anionic polymer (P2) covering the electrode active material and the dispersible anionic polymer (P1) existing as particles between the electrode active materials are bonded via a polyvalent cation (c) derived from a polyvalent cationic substance (C). In this case, a structure in which the dispersible anionic polymer (P1) and the dispersible anionic polymer (P1) are bonded via a polyvalent cation (c) may be further formed.

[0028] The soluble anionic polymer (P2) may or may not be included in the electrode binder composition. For example, the soluble anionic polymer (P2) may be included in the electrode slurry described later, or it may be added to the electrode slurry later during electrode manufacturing.

[0029] In the electrode binder composition, the amount of anions Y contained in the dispersible anionic polymer (P1) Ｐ１ The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ１ It is preferably 0.050 or higher, more preferably 0.10 or higher, even more preferably 0.15 or higher, even more preferably 0.70 or higher, even more preferably 1.3 or higher, and particularly preferably 1.7 or higher. Ｃ / Y Ｐ１ If the above range is maintained, a sufficient amount of polyvalent cations (c) for bonding with the soluble anionic polymer (P2) can be secured in the electrode active material layer.

[0030] In the electrode binder composition, the amount of anions Y contained in the dispersible anionic polymer (P1) Ｐ１The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ１ It is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and particularly preferably 2.5 or less. Ｃ / Y Ｐ１ When the above range is maintained, the dispersible anionic polymer (P1) and the polyvalent cation (c) derived from the polyvalent cationic substance (C) can be effectively bonded in the electrode active material layer.

[0031] In the electrode binder composition, the amount of anions Y contained in the dispersible anionic polymer (P1) Ｐ１ The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ１ This may be 0.050 to 5.0, 0.10 to 4.0, 0.15 to 3.0, 0.70 to 2.5, 1.3 to 2.5, or 1.7 to 2.5.

[0032] When the electrode binder composition contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ２ It is preferably 0.010 or higher, more preferably 0.030 or higher, even more preferably 0.045 or higher, even more preferably 0.25 or higher, even more preferably 0.45 or higher, and particularly preferably 0.60 or higher. Ｃ / Y Ｐ２ If the value is within the above range, a sufficient amount of polyvalent cations (c) for bonding with the dispersible anionic polymer (P1) can be secured in the electrode active material layer.

[0033] When the electrode binder composition contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ２ It is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.0 or less, and particularly preferably 0.75 or less. Ｃ / Y Ｐ２ When the above range is maintained, the soluble anionic polymer (P2) and the polyvalent cation (c) derived from the polyvalent cationic substance (C) can be effectively bonded in the electrode active material layer.

[0034] When the electrode binder composition contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ２ This can be 0.010 to 3.0, 0.030 to 2.0, 0.045 to 1.0, 0.25 to 0.75, 0.45 to 0.75, or 0.60 to 0.75.

[0035] When the electrode binder composition contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of anions Y contained in the dispersible anionic polymer (P1) relative to [the specified value]. Ｐ１ Ratio Y Ｐ１ / Y Ｐ２ It is preferably 0.10 or higher, more preferably 0.20 or higher, and even more preferably 0.30 or higher. Ｐ１ / Y Ｐ２ When the above range is maintained, sufficient bonding occurs between the dispersible anionic polymer (P1) and the soluble anionic polymer (P2).

[0036] When the electrode binder composition contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of anions Y contained in the dispersible anionic polymer (P1) relative to [the specified value]. Ｐ１ Ratio YＰ１ / Y Ｐ２ It is preferably 2.0 or less, more preferably 1.0 or less, and even more preferably 0.50 or less. Ｐ１ / Y Ｐ２ When the above range is maintained, sufficient bonding occurs between the dispersible anionic polymer (P1) and the soluble anionic polymer (P2).

[0037] When the electrode binder composition contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of anions Y contained in the dispersible anionic polymer (P1) relative to [the specified value]. Ｐ１ Ratio Y Ｐ１ / Y Ｐ２ This can be 0.10 to 2.0, 0.20 to 1.0, or 0.30 to 1.0.

[0038] When the electrode binder composition contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) per 100 parts by mass of the dispersible anionic polymer (P1) is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 70 parts by mass or more. When the content of the soluble anionic polymer (P2) is within the above range, it is easier to disperse the electrode active material when preparing the electrode slurry. In addition, it is easier to obtain a state in which the soluble anionic polymer (P2) covers the electrode active material in the electrode active material layer.

[0039] When the electrode binder composition contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) per 100 parts by mass of the dispersible anionic polymer (P1) is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less. When the content of the soluble anionic polymer (P2) is within the above range, it is easier to suppress the increase in viscosity of the electrode binder composition and electrode slurry. It is also easier to reduce the manufacturing cost of the electrode.

[0040] When the electrode binder composition contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) relative to 100 parts by mass of the dispersible anionic polymer (P1) may be 30 to 300 parts by mass, 50 to 200 parts by mass, or 70 to 150 parts by mass.

[0041] [Aqueous Medium] The electrode binder composition contains an aqueous medium. Examples of aqueous mediums include water, a hydrophilic solvent, or a mixture thereof. Examples of hydrophilic solvents include methanol, ethanol, isopropyl alcohol, N-methylpyrrolidone, etc. From the viewpoint of availability and cost, it is preferable that the aqueous medium contains water. If the aqueous medium contains water, the water content may be 50% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass of the total aqueous medium.

[0042] [Dispersible Anionic Polymer (P1)] The electrode binder composition contains a dispersible anionic polymer (P1). The dispersible anionic polymer (P1) has anionic functional groups. Examples of anionic functional groups include carboxyl groups, sulfol groups, and phosphate groups, with carboxyl groups and sulfol groups being preferred, and carboxyl groups being more preferred. It is preferable that the dispersible anionic polymer (P1) does not have cationic functional groups, but it may contain cationic functional groups to the extent that the function of the dispersible anionic polymer (P1) is not inhibited. For example, the dispersible anionic polymer (P1) may contain cationic functional groups in an amount of 0.050 times or less, more preferably 0.010 times or less, the amount of anionic functional groups (mol).

[0043] Of all the anionic functional groups contained in the dispersible anionic polymer (P1), the content of carboxyl groups is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

[0044] The dispersible anionic polymer (P1) may contain structural units derived from monomers (anionic compounds) having anionic functional groups. In this case, the anionic compound may be a monovalent anionic compound (a compound containing one anionic group in one molecule) or a divalent or more anionic compound (a compound containing two or more anionic groups in one molecule). In the dispersible anionic polymer (P1), the proportion of structural units derived from monovalent anionic compounds among all structural units derived from anionic compounds is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and may be 100 mol%. When the proportion of structural units derived from monovalent anionic compounds is within the above range, inhibition of intermolecular bonding of the polymer caused by one polyvalent cation (c) bonding with multiple anionic functional groups within the molecule of the dispersible anionic polymer (P1) is less likely to occur.

[0045] The main chain of the dispersible anionic polymer (P1) preferably consists of carbon-carbon bonds. Here, structures other than the carbon-carbon bonds at the terminals of the dispersible anionic polymer (P1) are not included in the main chain. The dispersible anionic polymer (P1) may also have a crosslinked structure.

[0046] In the electrode binder composition, the dispersible anionic polymer (P1) is dispersed in an aqueous medium. The dispersible anionic polymer (P1) may be partially dissolved in the aqueous medium, even if it is not completely dissolved. The solubility of the dispersible anionic polymer (P1) in the aqueous medium is preferably 0.50 g / 100 g or less.

[0047] Amount of anions per gram of dispersible anionic polymer (P1) A Ｐ１ The amount of anion A is preferably 0.30 mmol / g or more, more preferably 0.50 mmol / g or more, even more preferably 0.70 mmol / g or more, and particularly preferably 0.80 mmol / g or more. Ｐ１ When the range is within the above range, the dispersible anionic polymer (P1) and the polyvalent cation (c) can be effectively bonded in the electrode active material layer.

[0048] Amount of anions per gram of dispersible anionic polymer (P1) A Ｐ１ The amount is preferably 4.0 mmol / g or less, more preferably 3.0 mmol / g or less, even more preferably 2.0 mmol / g or less, and particularly preferably 1.2 mmol / g or less. Anion amount A Ｐ１ When the pH is within the above range, it is easy to adjust the pH of the electrode binder composition or the electrode slurry obtained using the electrode binder composition. Furthermore, inhibition of intermolecular bonding of the polymer, which occurs when one polyvalent cation (c) binds to multiple anionic functional groups within the molecule of the dispersible anionic polymer (P1), is effectively suppressed.

[0049] Amount of anions per gram of dispersible anionic polymer (P1) A Ｐ１ The amount may be 0.30 mmol / g to 4.0 mmol / g, 0.50 mmol / g to 3.0 mmol / g, 0.70 mmol / g to 2.0 mmol / g, or 0.80 mmol / g to 1.2 mmol / g.

[0050] The glass transition temperature Tg of the dispersible anionic polymer (P1) is preferably -30°C or higher, more preferably -10°C or higher, and even more preferably 0°C or higher. When the glass transition temperature Tg is within the above range, the cycle characteristics of the non-aqueous secondary battery made using the dispersible anionic polymer (P1) tend to improve.

[0051] The glass transition temperature Tg of the dispersible anionic polymer (P1) is preferably 100°C or lower, more preferably 50°C or lower, and even more preferably 30°C or lower. When the glass transition temperature Tg is within the above range, the adhesion of the electrode active material layer containing the dispersible anionic polymer (P1) to the current collector foil tends to improve.

[0052] The glass transition temperature Tg of the dispersible anionic polymer (P1) may be -30°C to 100°C, -10°C to 50°C, or 0°C to 30°C.

[0053] In this disclosure, the glass transition temperature Tg of the dispersible anionic polymer (P1) is the temperature corresponding to the peak top of the DDSC chart obtained as the temperature derivative of the DSC measured at a heating rate of 10°C / min under a nitrogen gas atmosphere. An example of a measuring device is the EXSTAR DSC / SS7020 manufactured by Hitachi High-Tech Science Corporation.

[0054] The dispersible anionic polymer (P1) preferably forms particles in the electrode binder composition. The particles formed by the dispersible anionic polymer (P1) may contain other components such as a polyvalent cationic substance (C) and a surfactant.

[0055] The particle diameter D50 formed by the dispersible anionic polymer (P1) is preferably 0.050 μm or larger, more preferably 0.10 μm or larger, and even more preferably 0.15 μm or larger.

[0056] The particle diameter D50 formed by the dispersible anionic polymer (P1) is preferably 1.0 μm or less, more preferably 0.50 μm or less, even more preferably 0.30 μm or less, and particularly preferably 0.25 μm or less.

[0057] The particle diameter D50 formed by the dispersible anionic polymer (P1) may be 0.050 μm to 1.0 μm, 0.10 μm to 0.50 μm, or 0.15 μm to 0.30 μm.

[0058] In this disclosure, the particle diameter D50 is a volume-based value measured by dynamic light scattering. An example of a measuring device is the NANOTRAC WAVE II.

[0059] The dispersible anionic polymer (P1) may be a polymer of a compound having an ethylenically unsaturated group. The method for synthesizing the polymer of the compound having an ethylenically unsaturated group is not particularly limited and can be carried out by known methods.

[0060] A preferred example of a dispersible anionic polymer (P1) includes a first structural unit derived from a nonionic aromatic unsaturated compound, a second structural unit derived from a nonionic aliphatic unsaturated compound, and a third structural unit derived from an anionic unsaturated compound. Another preferred example of a dispersible anionic polymer (P1) includes, in addition to the first, second, and third structural units, at least one selected from the group consisting of a fourth structural unit derived from a conjugated diene compound, a fifth structural unit derived from an internal crosslinking agent, and a sixth structural unit derived from a polymerizable surfactant. Specific examples of monomers constituting each structural unit are shown below. Each structural unit may consist of only one monomer or a combination of two or more monomers. Hereinafter, compounds that fall under either anionic unsaturated compounds or polymerizable surfactants will be described as "polymerizable surfactants."

[0061] (First structural unit: Nonionic aromatic unsaturated compound) The nonionic aromatic unsaturated compound constituting the first structural unit is a nonionic aromatic compound having one independent ethylenically unsaturated bond. The nonionic aromatic unsaturated compound preferably has an aryl group, and more preferably a phenyl group. A vinyl group is preferred as the ethylenically unsaturated bond.

[0062] Examples of nonionic aromatic unsaturated compounds include styrene, t-butylstyrene, p-methylstyrene, and benzyl (meth)acrylate. The nonionic aromatic unsaturated compound preferably contains an aromatic vinyl compound, more preferably contains at least one selected from the group consisting of styrene and styrene derivatives, and even more preferably contains styrene.

[0063] When the dispersible anionic polymer (P1) contains a first structural unit, the content of the first structural unit is preferably 25% by mass or more of the total structural units, more preferably 35% by mass or more, and even more preferably 40% by mass or more.

[0064] When the dispersible anionic polymer (P1) contains a first structural unit, the content of the first structural unit is preferably 65% ​​by mass or less of the total structural units, more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0065] (Second structural unit: Nonionic aliphatic unsaturated compound) The nonionic aliphatic unsaturated compound that constitutes the second structural unit is a nonionic aliphatic compound having one (meth)acryloyl group. The nonionic aliphatic unsaturated compound does not have any ethylenically unsaturated bonds other than the (meth)acryloyl group.

[0066] Nonionic aliphatic unsaturated compounds preferably contain (meth)acrylate esters, and more preferably contain alkyl (meth)acrylate esters. Specific examples of alkyl (meth)acrylate esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate.

[0067] Nonionic aliphatic unsaturated compounds may have nonionic functional groups. Examples of nonionic functional groups include hydroxyl groups and cyano groups, with hydroxyl groups being preferred. Specific examples of nonionic aliphatic unsaturated compounds having hydroxyl groups include 2-hydroxymethyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate.

[0068] When the dispersible anionic polymer (P1) contains a second structural unit, the content of the second structural unit is preferably 25% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, of the total structural units. However, when the dispersible anionic polymer (P1) contains a fourth structural unit, the preferred content of the second structural unit is not limited to the above range.

[0069] When the dispersible anionic polymer (P1) contains a second structural unit, the content of the second structural unit is preferably 70% by mass or less of the total structural units, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0070] (Third structural unit: Anionic unsaturated compound) The anionic unsaturated compound constituting the third structural unit is a compound having one independent ethylenically unsaturated bond and an anionic functional group. Examples of anionic functional groups include carboxyl groups, sulfol groups, and phosphate groups, with carboxyl groups and sulfol groups being preferred. The anionic functional group may form a salt such as a sodium salt. The anionic unsaturated compound is preferably an aliphatic compound. The anionic unsaturated compound may have one anionic functional group in one molecule, or it may have two or more anionic functional groups in one molecule.

[0071] Examples of anionic unsaturated compounds include unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; half-esters of unsaturated dicarboxylic acids; and p-styrene sulfonic acid. Among these, (meth)acrylic acid, itaconic acid, and p-styrene sulfonic acid are preferred as anionic unsaturated compounds, and it is more preferable that the compound contains at least (meth)acrylic acid.

[0072] When the dispersible anionic polymer (P1) contains a third structural unit, the content of the third structural unit is preferably 0.30% by mass or more, more preferably 0.80% by mass or more, and even more preferably 1.30% by mass or more, of the total structural units.

[0073] When the dispersible anionic polymer (P1) contains a third structural unit, the content of the third structural unit is preferably 15% by mass or less of the total structural units, more preferably 10% by mass or less, and even more preferably 8% by mass or less.

[0074] (Fourth structural unit: Conjugated diene compound) The conjugated diene compound constituting the fourth structural unit is a nonionic aliphatic compound having one conjugated diene structure. The conjugated diene compound does not have ethylenically unsaturated bonds other than the conjugated diene structure. The conjugated diene compound preferably contains compounds with 10 or fewer carbon atoms, and more preferably contains compounds with 5 or fewer carbon atoms. The conjugated diene compound preferably contains hydrocarbons.

[0075] Examples of conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2,3-dimethylbutadiene, 2-chloro-1,3-butadiene, 3-methyl-1,3-pentadiene, isoprene (2-methyl-1,3-butadiene), and others.

[0076] When the dispersible anionic polymer (P1) contains a fourth structural unit, the content of the fourth structural unit is preferably 15% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, of the total structural units.

[0077] When the dispersible anionic polymer (P1) contains a fourth structural unit, the content of the fourth structural unit is preferably 55% by mass or less, more preferably 45% by mass or less, and even more preferably 35% by mass or less of the total structural units.

[0078] (Fifth structural unit: Internal crosslinking agent) The internal crosslinking agent constituting the fifth structural unit is a compound having multiple independent ethylenically unsaturated bonds. The ethylenically unsaturated bonds contained in the internal crosslinking agent are preferably vinyl groups bonded to an aryl group, or (meth)acryloyl groups, and more preferably vinyl groups bonded to an aryl group. The number of ethylenically unsaturated bonds contained in the internal crosslinking agent is preferably 2 to 4, more preferably 2 or 3, and even more preferably 2. The internal crosslinking agent is preferably a nonionic compound.

[0079] Examples of internal crosslinking agents include divinylbenzene, trimethylolpropane triacrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 2-hydroxy-3-acryloyloxypropyl methacrylate.

[0080] When the dispersible anionic polymer (P1) contains a fifth structural unit, the content of the fifth structural unit is preferably 0.010% by mass or more, more preferably 0.030% by mass or more, and even more preferably 0.040% by mass or more, of the total structural units.

[0081] When the dispersible anionic polymer (P1) contains a fifth structural unit, the content of the fifth structural unit is preferably 1.0% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.10% by mass or less, of the total structural units.

[0082] (Sixth structural unit: polymerizable surfactant) The polymerizable surfactant constituting the sixth structural unit is a compound that has one independent ethylenically unsaturated bond and functions as a surfactant. The polymerizable surfactant preferably includes anionic surfactants, and more preferably includes at least one selected from the group consisting of sulfonates and sulfate ester salts. The molecular weight of the polymerizable surfactant is not particularly limited and may be selected from, for example, the range of 300 to 1000. The polymerizable surfactant may also include a compound represented by the following formula (1).

[0083]

[0084] In formula (1), R is an alkyl group or a hydrogen atom, and n is an integer from 1 to 20. R is preferably an alkyl group having 10 to 40 carbon atoms, and more preferably a linear unsubstituted alkyl group having 10 to 40 carbon atoms. n is preferably an integer from 10 to 12.

[0085] When the dispersible anionic polymer (P1) contains a sixth structural unit, the content of the sixth structural unit is preferably 0.10% by mass or more, more preferably 0.20% by mass or more, and even more preferably 0.30% by mass or more.

[0086] When the dispersible anionic polymer (P1) contains a sixth structural unit, the content of the sixth structural unit is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less.

[0087] [Polyvalent Cationic Substance (C)] The electrode binder composition contains a polyvalent cationic substance (C). The polyvalent cationic substance (C) is a compound capable of forming a polyvalent cation (c) in an aqueous medium. The polyvalent cationic substance (C) is preferably capable of forming a divalent or trivalent cation as the polyvalent cation (c), and more preferably capable of forming a divalent cation.

[0088] The polyvalent cationic substance (C) may or may not be capable of forming a polyvalent cation (c) in an aqueous medium on its own. For example, the polyvalent cationic substance (C) may not form a polyvalent cation (c) in an aqueous medium on its own, but may form a polyvalent cation (c) in the presence of other components (acids, alkalis, etc.).

[0089] From the viewpoint of the ease of generating polyvalent cations (c) in an aqueous medium and the ease of forming bonds between polyvalent cations (c) and anionic functional groups, the polyvalent cationic substance (C) preferably contains at least one selected from the group consisting of metals and metal compounds, and more preferably contains a metal compound. Examples of metal compounds include metal oxides and metal complexes, with metal oxides being preferred. Examples of metals include zinc, zirconium, magnesium, aluminum, calcium, copper, iron, manganese, and chromium. Examples of metal compounds include compounds containing the aforementioned metals. The metal compound preferably contains at least one selected from the group consisting of zinc compounds, zirconium compounds, magnesium compounds, aluminum compounds, calcium compounds, copper compounds, iron compounds, manganese compounds, and chromium compounds, more preferably contains a zinc compound, and even more preferably contains zinc oxide. The polyvalent cationic substance (C) contained in the electrode binder composition may be one type or two or more types.

[0090] [Soluble Anionic Polymer (P2)] The electrode binder composition may contain a soluble anionic polymer (P2). The soluble anionic polymer (P2) has an anionic functional group. The anionic functional group is preferably a carboxyl group or a sulfo group, with the carboxyl group being more preferred. In the electrode binder composition, the soluble anionic polymer (P2) dissolves in the aqueous medium. The solubility of the soluble anionic polymer (P2) in the aqueous medium is preferably 10 g / 100 g or more.

[0091] In the electrode binder composition, the amount of anions A per 1 g of soluble anionic polymer (P2) Ｐ２ The concentration is preferably 1.0 mmol / g or more, more preferably 1.5 mmol / g or more, even more preferably 2.0 mmol / g or more, and particularly preferably 2.5 mmol / g or more. Ｐ２ When the above range is maintained, the soluble anionic polymer (P2) and the polyvalent cation (c) can be effectively bonded in the electrode active material layer.

[0092] In the electrode binder composition, the amount of anions A per 1 g of soluble anionic polymer (P2) Ｐ２ The concentration is preferably 7.5 mmol / g or less, more preferably 6.0 mmol / g or less, even more preferably 5.0 mmol / g or less, and particularly preferably 4.0 mmol / g or less. Ｐ２ When the pH is within the above range, it is easy to adjust the pH of the electrode binder composition or the electrode slurry obtained using the electrode binder. Furthermore, inhibition of intermolecular bonding of the polymer, which occurs when one polyvalent cation (c) binds to multiple anionic functional groups within the molecule of the soluble anionic polymer (P2), is effectively suppressed.

[0093] In the electrode binder composition, the amount of anions A per 1 g of soluble anionic polymer (P2) Ｐ２The amount may be 1.0 mmol / g to 7.5 mmol / g, 1.5 mmol / g to 6.0 mmol / g, 2.0 mmol / g to 5.0 mmol / g, or 2.5 mmol / g to 4.0 mmol / g.

[0094] A suitable example of a soluble anionic polymer (P2) is a cellulose derivative. Cellulose derivatives have a structure in which at least some of the hydrogen atoms of the hydroxyl groups contained in cellulose are substituted. Cellulose derivatives are thought to contribute significantly to the formation of conductive paths between electrode active materials and between the electrode active material and the current collector in the electrode active material layer. Furthermore, when a cellulose derivative is added to the electrode slurry containing the electrode active material during the electrode manufacturing process, the dispersibility of the electrode active material is improved, and the manufacturing cost of the electrode tends to decrease.

[0095] Examples of cellulose derivatives include carboxymethylcellulose (CMC), hydroxyethylcellulose, hydroxypropylcellulose, and salts of CMC. A single cellulose derivative may be used, or two or more may be used in combination. The cellulose derivative preferably contains at least one selected from the group consisting of CMC and salts of CMC, and more preferably contains a salt of CMC. Examples of salts of CMC include alkali metal salts of CMC and ammonium salts of CMC, with alkali metal salts of CMC being preferred. The alkali metal in the alkali metal salt is preferably Na, K, or Li, and more preferably Na.

[0096] The degree of etherification of the cellulose derivative included as the soluble anionic polymer (P2) is preferably 0.50 or higher, more preferably 0.55 or higher, and even more preferably 0.60 or higher. When the degree of etherification of the cellulose derivative is within the above range, the cellulose derivative can be efficiently bonded with the polyvalent cation (c).

[0097] The degree of etherification of the cellulose derivative included as the soluble anionic polymer (P2) is preferably 2.5 or less, more preferably 1.5 or less, and even more preferably 1.0 or less. When the degree of etherification of the cellulose derivative is within the above range, it is easier to adjust the pH of the electrode binder composition and electrode slurry. Furthermore, inhibition of intermolecular bonding of the polymer, which occurs when one polyvalent cation (c) bonds with multiple anionic functional groups within the cellulose derivative molecule, is suppressed.

[0098] The degree of etherification of the cellulose derivative included as the soluble anionic polymer (P2) may be 0.50 to 2.5, 0.55 to 1.5, or 0.60 to 1.0.

[0099] In this disclosure, the degree of etherification of a cellulose derivative is the number of etherified hydroxyl groups per structural unit out of the three hydroxyl groups contained in one structural unit of cellulose. Here, etherification means that a hydrogen atom of a hydroxyl group is substituted by a structure containing a carboxyl group. The degree of etherification is as described in Non-Patent Document 1. １３ This is a value measured by 13C NMR. In this case, in order to facilitate the determination of the integrated signal, one or both of the etherified substituents and the hydroxyl group may be converted to other substituents as needed. If the cellulose derivative is CMC or a salt thereof, the carboxyl group or salt thereof of the etherified portion is methyl esterified, and the hydroxyl group is propionylated, １３ Measurements will be performed using 13C NMR.

[0100] The weight-average molecular weight of the cellulose derivative is preferably 800,000 or more, more preferably 1,200,000 or more, and even more preferably 1,600,000 or more. When the weight-average molecular weight of the cellulose derivative is within the above range, the binding between electrode active materials, or between electrode active materials and current collectors, tends to improve. Furthermore, the formation of conductive paths between electrode active materials, or between electrode active materials and current collectors, is promoted, and the electrode resistance tends to decrease.

[0101] The weight-average molecular weight of the cellulose derivative is preferably 10 million or less, more preferably 5 million or less, and even more preferably 3 million or less. When the weight-average molecular weight of the cellulose derivative is within the above range, the increase in viscosity of the liquid (such as a slurry) when manufacturing a liquid (such as a slurry) containing the cellulose derivative tends to be suppressed, and the workability of stirring tends to improve. In addition, the applicability of the liquid containing the cellulose derivative tends to improve.

[0102] The weight-average molecular weight of the cellulose derivative may be 800,000 to 10,000,000, 1,200,000 to 5,000,000, or 1,600,000 to 3,000,000.

[0103] In this disclosure, the weight-average molecular weight of the cellulose derivative is the pullulan equivalent value measured by GPC. The specific measurement conditions are as follows: GPC instrument: GPC-101 (manufactured by Resonaq Corporation) Solvent: 0.1 M NaNO ３ Aqueous solution sample column: Shodex Column Ohpak SB-806 HQ (8.0 mm I.D. x 300 mm) x 2 Reference column: Shodex Column Ohpak SB-800 RL (8.0 mm I.D. x 300 mm) x 2 Column temperature: 40°C Sample concentration: 0.1% by mass Detector: RI-71S (Shimadzu Corporation) Flow rate: 1 ml / min Molecular weight standards: Pullulan (P-5, P-10, P-20, P-50, P-100, P-200, P-400, P-800, P-1300 and P-2500, Resonaq Corporation)

[0104] [Basic Substances] The electrode binder composition may contain basic substances. Basic substances neutralize the acidic components contained in the electrode binder composition and adjust the pH. By adjusting the pH of the electrode binder composition, the mechanical and chemical stability of the electrode binder composition can be improved. The pH of the electrode binder composition may be adjusted as appropriate depending on the electrode specifications, slurry preparation conditions described later, etc.

[0105] Examples of basic substances include ammonia, triethylamine, sodium hydroxide, and lithium hydroxide. The electrode binder composition may contain one or more basic substances.

[0106] [Surfactants] The electrode binder composition may contain surfactants. Surfactants perform functions such as improving the dispersion stability of dispersible anionic polymers (P1), etc. It is preferable to use anionic surfactants or nonionic surfactants as such surfactants. Surfactants may be included in the electrode binder composition as polymerization components of the dispersible anionic polymer (P1).

[0107] Examples of anionic surfactants include alkylbenzene sulfonates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, and fatty acid salts. Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polycyclic phenyl ethers, polyoxyalkylene alkyl ethers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters. The electrode binder composition may contain only one or two or more surfactants.

[0108] The non-volatile content concentration of the electrode binder composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. When the non-volatile content concentration of the electrode binder composition is within the above range, a sufficient amount of the active ingredient contained in the electrode binder composition can be secured.

[0109] The non-volatile content concentration of the electrode binder composition is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. When the non-volatile content concentration of the electrode binder composition is within the above range, the increase in viscosity of the electrode binder composition can be effectively suppressed, and each component contained in the electrode binder composition can be sufficiently dispersed or dissolved in the aqueous medium.

[0110] The total content of the dispersible anionic polymer (P1) and the polyvalent cationic substance (C) in the nonvolatile content of the electrode binder composition is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass. When the total content of the dispersible anionic polymer (P1) and the polyvalent cationic substance (C) is within the above range, the effects of these components contained in the electrode binder composition can be fully exerted. If the electrode binder composition further contains a soluble anionic polymer (P2), it is preferable that the total content of the dispersible anionic polymer (P1), the polyvalent cationic substance (C), and the soluble anionic polymer (P2) is within the above range.

[0111] <Electrode Slurry> One embodiment of the present disclosure is an electrode slurry comprising: an aqueous medium; an electrode active material; a dispersible anionic polymer (P1) having an anionic functional group and dispersed in the aqueous medium; and a polyvalent cationic substance (C) capable of forming a polyvalent cation (c) in the aqueous medium.

[0112] The electrode slurry of this embodiment is preferably for manufacturing electrodes for non-aqueous secondary batteries, and more preferably for manufacturing negative electrodes for non-aqueous secondary batteries.

[0113] The electrode slurry of this embodiment preferably further comprises a soluble anionic polymer (P2) having anionic functional groups and soluble in an aqueous medium. Details and preferred embodiments of the aqueous medium, dispersible anionic polymer (P1), soluble anionic polymer (P2), and polyvalent cationic substance (C) are as described above.

[0114] [Electrode Active Material] The electrode slurry includes an electrode active material. In this disclosure, "electrode active material" means a material from which charge carrier ions, such as lithium ions, can be inserted and deintercalated. The charge carrier ions are preferably alkali metal ions, more preferably selected from lithium ions, sodium ions, and potassium ions, and even more preferably lithium ions.

[0115] When the electrode manufactured using the electrode slurry is the negative electrode, the electrode slurry contains a negative electrode active material as the electrode active material. The type of negative electrode active material is not particularly limited and can be selected according to the application of the non-aqueous secondary battery. Preferably, the negative electrode active material contains at least one selected from the group consisting of carbon materials, silicon-containing materials, and titanium-containing materials. The material used as the negative electrode active material may be used alone, in combination of two or more materials, or as a composite of two or more materials.

[0116] Carbon materials used as negative electrode active materials include coke such as petroleum coke, pitch coke, and coal coke, carbonized organic polymers, and graphite such as artificial graphite and natural graphite. Silicon-containing materials used as negative electrode active materials include elemental silicon and silicon compounds such as silicon oxide. Titanium-containing materials used as negative electrode active materials include lithium titanate.

[0117] The negative electrode active material preferably contains at least one material selected from the group consisting of carbon materials and silicon-containing materials. In this case, the effect of improving the binding between negative electrode active materials or between the negative electrode active material and the current collector by the dispersible anionic polymer (P1) contained in the electrode slurry tends to be significantly exhibited.

[0118] When the electrode manufactured using electrode slurry is the positive electrode, the electrode slurry contains a positive electrode active material. The type of positive electrode active material is not particularly limited and can be selected according to the application of the non-aqueous secondary battery. As the positive electrode active material, a material with a higher standard electrode potential than the negative electrode active material is used. Specifically, as the positive electrode active material, nickel-containing lithium composite oxides such as Ni-Co-Mn lithium composite oxides, Ni-Mn-Al lithium composite oxides, and Ni-Co-Al lithium composite oxides, and lithium cobalt oxide (LiCoO) are used. ２ ), spinel-type lithium manganate (LiMn ２ O ４ ), olivine-type lithium iron phosphate, TiS ２ MnO ２ MoO ３ , V２ O ５ Examples include chalcogen compounds such as those mentioned above. The substance used as the positive electrode active material may be used alone or in combination of two or more.

[0119] From the viewpoint of significantly exhibiting the effects of this disclosure, it is preferable that the electrode slurry contains graphite as the electrode active material. In this case, it is preferable that the amount of graphite be 50% by mass or more of the total electrode active material, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0120] [Other Components] The electrode slurry may contain components other than those listed above. For example, the electrode slurry may contain a conductive additive. Examples of conductive additives that may be included in the electrode slurry include carbon materials such as carbon black and carbon fibers. Examples of carbon black include furnace black, acetylene black, Denka Black (manufactured by Denka Co., Ltd.), and Ketjen Black (manufactured by Ketjen Black International Co., Ltd.). Examples of carbon fibers include carbon nanotubes and carbon nanofibers. An example of carbon nanotubes is VGCF (manufactured by Resonac Co., Ltd.), which is a gas-phase carbon fiber.

[0121] The electrode slurry may contain basic substances and may contain conductive additives. Examples of basic substances and surfactants that may be included in the electrode slurry include basic substances and surfactants that may be included in the electrode binder composition described above.

[0122] [Non-volatile content concentration of electrode slurry] The non-volatile content concentration of the electrode slurry is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. When the non-volatile content concentration of the electrode slurry is within the above range, the concentration of the active ingredient in the electrode slurry is sufficiently ensured, and a sufficient amount of electrode active material layer can be formed with a small amount of electrode slurry. In addition, the viscosity of the electrode slurry can be increased to a level suitable for coating, and the drying time after coating of the electrode slurry can be shortened.

[0123] The non-volatile content concentration of the electrode slurry is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the non-volatile content concentration of the electrode slurry is within the above range, the dispersibility of the electrode active material in the electrode slurry can be improved, and the coating properties of the electrode slurry can be improved.

[0124] [Content of each component in the electrode slurry] In the electrode slurry, the total content of the electrode active material, dispersible anionic polymer (P1), optionally included soluble anionic polymer (P2), and polyvalent cationic substance (C) in the nonvolatile components is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass.

[0125] In the electrode slurry, the content of electrode active material in the nonvolatile matter is preferably 75% by mass or more, more preferably 85% by mass or more, and even more preferably 95% by mass or more. When the content of electrode active material is within the above range, the charge and discharge capacity of the electrode manufactured using the electrode slurry can be improved. Considering the content of components other than electrode active material, the content of electrode active material in the nonvolatile matter is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less.

[0126] In the electrode slurry, the content of the electrode active material in the nonvolatile components may be 75% to 99% by mass, 85% to 98% by mass, or 95% to 97% by mass.

[0127] In the electrode slurry, the content of the dispersible anionic polymer (P1) in the nonvolatile components is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 1.2% by mass or more. When the content of the dispersible anionic polymer (P1) is within the above range, the electrode active materials can be sufficiently bonded to each other, or to the electrode active materials and the current collector.

[0128] In the electrode slurry, the content of the dispersible anionic polymer (P1) in the nonvolatile components is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less. When the content of the dispersible anionic polymer (P1) is within the above range, the content of the electrode active material in the electrode active material layer produced using the electrode slurry can be increased, and the charge-discharge capacity of the electrode can be improved.

[0129] In the electrode slurry, the content of the dispersible anionic polymer (P1) in the nonvolatile components may be 0.5% to 5.0% by mass, 1.0% to 3.0% by mass, or 1.2% to 2.0% by mass.

[0130] When the electrode slurry contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) in the nonvolatile components of the electrode slurry is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. When the content of the soluble anionic polymer (P2) is within the above range, the electrode active material disperses easily in the electrode slurry. In addition, a sufficient film of the soluble anionic polymer (P2) can be formed on the surface of the electrode active material, which contributes to improving the binding force between the electrode active materials themselves, or between the electrode active material and the current collector.

[0131] When the electrode slurry contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) in the nonvolatile components of the electrode slurry is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less. When the content of the soluble anionic polymer (P2) is within the above range, the content of the electrode active material in the electrode active material layer produced using the electrode slurry can be increased, thereby improving the charge-discharge capacity of the electrode. In addition, an excessive increase in the viscosity of the electrode slurry can be suppressed.

[0132] When the electrode slurry contains the soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) in the non-volatile matter in the electrode slurry may be 0.5% by mass to 5.0% by mass, may be 1.0% by mass to 3.0% by mass, or may be 1.2% by mass to 2.0% by mass.

[0133] In the electrode slurry, the amount of anions Y Ｐ１ contained in the dispersible anionic polymer (P1) Ｃ with respect to the amount of cations X Ｃ of the polyvalent cationic substance (C) Ｐ１ The preferred range of the ratio X Ｃ / Y Ｐ１ is the same as the preferred range of X

[0134] When the electrode slurry contains the soluble anionic polymer (P2), the amount of anions Y Ｐ２ contained in the soluble anionic polymer (P2) in the electrode slurry Ｃ with respect to the amount of cations X Ｃ of the polyvalent cationic substance (C) Ｐ２ The preferred range of the ratio X Ｃ / Y Ｐ２ is the same as the preferred range of X

[0135] When the electrode slurry contains the soluble anionic polymer (P2), the amount of anions Y Ｐ２ contained in the soluble anionic polymer (P2) in the electrode slurry Ｐ１ with respect to the amount of anions Y Ｐ１ contained in the dispersible anionic polymer (P1) Ｐ２ The preferred range of the ratio Y Ｐ１ / Y Ｐ２ is the same as the preferred range of Y

[0136] When the electrode slurry contains the soluble anionic polymer (P2), the preferred range of the content of the soluble anionic polymer (P2) with respect to 100 parts by mass of the content of the dispersible anionic polymer (P1) is the same as the preferred range of the content of the soluble anionic polymer (P2) in the electrode binder composition.

[0137] [Method for Manufacturing Electrode Slurry] The method for manufacturing an electrode slurry involves mixing an electrode active material, an aqueous medium, a dispersible anionic polymer (P1) having anionic functional groups, and a polyvalent cationic substance (C). In the method for manufacturing the electrode slurry, a soluble anionic polymer (P2) may be further mixed. In addition, other components, such as conductive additives and surfactants, may be mixed as needed in the method for manufacturing the electrode slurry. The mixing order of the components that make up the electrode slurry is not particularly limited.

[0138] One example of a method for producing an electrode slurry is to mix a soluble anionic polymer (P2), an electrode active material, and other components as needed into a pre-prepared electrode binder composition containing an aqueous medium, a dispersible anionic polymer (P1), and a polyvalent cationic substance (C). In this method, the soluble anionic polymer (P2) may be included in the pre-prepared electrode binder composition. The aqueous medium included in the electrode slurry may be the aqueous medium included in the electrode binder composition as is, or an additional aqueous medium may be added to the aqueous medium included in the electrode binder composition. Furthermore, a portion of the aqueous medium may be removed during the electrode slurry production process.

[0139] Another example of a method for producing an electrode slurry is a mixture of an aqueous medium, a dispersible anionic polymer (P1), a polyvalent cationic substance (C), a soluble anionic polymer (P2), an electrode active material, and other components as needed.

[0140] Methods for mixing the components of the electrode slurry include using mixing devices such as agitators, rotary mixers, and shakers.

[0141] <Electrode> One embodiment of the present disclosure is an electrode having a current collector and an electrode active material layer, wherein the electrode active material layer comprises an electrode active material, a dispersible anionic polymer (P1) having anionic functional groups and dispersed in an aqueous medium, and a polyvalent cation (c).

[0142] The electrode in this embodiment is preferably an electrode for a non-aqueous secondary battery, and more preferably a negative electrode for a non-aqueous secondary battery.

[0143] In the electrode according to this embodiment, the electrode active material layer is arranged, for example, so as to be in contact with at least a portion of the surface of the current collector. The area on the surface of the current collector over which the electrode active material layer is formed is not particularly limited; the electrode active material layer may be formed over the entire surface of the current collector, or it may be formed over a portion of the surface of the current collector. If the current collector is in the form of a sheet, the electrode active material layer may be formed on one side of the sheet-like current collector or on both sides. The shape of the electrode may be a laminate, a wound body, etc., and is not particularly limited.

[0144] [Current Collector] The electrode includes a current collector. The current collector preferably contains a metal. Examples of metals that can be included include iron, copper, aluminum, nickel, and stainless steel. When the electrode of this disclosure is the negative electrode of a lithium-ion secondary battery, the current collector preferably contains copper. The shape of the current collector is preferably a sheet, including plates and foils. The thickness of the sheet-like current collector is not particularly limited and may be in the range of 0.001 mm to 0.5 mm.

[0145] [Electrode Active Material Layer] The electrode includes an electrode active material layer. The electrode active material layer includes an electrode active material, a dispersible anionic polymer (P1), and a polyvalent cation (c). The electrode active material layer may further include a soluble anionic polymer (P2). The electrode active material layer may further include other components such as a conductive additive, a basic substance, and a surfactant. Details and preferred embodiments of the electrode active material, dispersible anionic polymer (P1), soluble anionic polymer (P2), conductive additive, basic substance, and surfactant contained in the electrode active material layer are as described above.

[0146] The electrode active material layer contains a polyvalent cation (c). The polyvalent cation (c) is a cation with a valency of 2 or higher, preferably a cation with a valency of 2 or 3, and more preferably a cation with a valency of 2. The polyvalent cation (c) may be, for example, a polyvalent cationic substance (C) contained in an electrode binder composition or electrode slurry used in the manufacture of electrodes that has been converted into a polyvalent cation. In this disclosure, the polyvalent cation (c) is referred to as "polyvalent cation (c)" even when it forms an ionic bond with an anionic compound.

[0147] In the electrode active material layer, the amount of anions Y contained in the dispersible anionic polymer (P1) Ｐ１ The amount of polyvalent cation (c) X ｃ Ratio X ｃ / Y Ｐ１ It is preferably 0.050 or higher, more preferably 0.10 or higher, even more preferably 0.15 or higher, even more preferably 0.70 or higher, even more preferably 1.3 or higher, and particularly preferably 1.7 or higher. ｃ / Y Ｐ１ If the above range is maintained, a sufficient amount of polyvalent cations (c) for bonding with the soluble anionic polymer (P2) can be secured in the electrode active material layer.

[0148] In the electrode active material layer, the amount of anions Y contained in the dispersible anionic polymer (P1) Ｐ１ The amount of polyvalent cation (c) X ｃ Ratio X ｃ / Y Ｐ１ It is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less, and particularly preferably 2.5 or less. ｃ / Y Ｐ１ When the range is within the above range, the dispersible anionic polymer (P1) and the polyvalent cation (c) can be effectively bonded in the electrode active material layer.

[0149] In the electrode active material layer according to this embodiment, the amount of anions Y contained in the dispersible anionic polymer (P1) Ｐ１The amount of polyvalent cation (c) X ｃ Ratio X ｃ / Y Ｐ１ This may be 0.050 to 5.0, 0.10 to 4.0, 0.15 to 3.0, 0.70 to 2.5, 1.3 to 2.5, or 1.7 to 2.5.

[0150] When the electrode active material layer contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of polyvalent cation (c) X ｃ Ratio X ｃ / Y Ｐ２ It is preferably 0.010 or higher, more preferably 0.030 or higher, even more preferably 0.045 or higher, even more preferably 0.25 or higher, even more preferably 0.45 or higher, and particularly preferably 0.60 or higher. ｃ / Y Ｐ２ If the value is within the above range, a sufficient amount of polyvalent cations (c) for bonding with the dispersible anionic polymer (P1) can be secured in the electrode active material layer.

[0151] When the electrode active material layer contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of polyvalent cation (c) X ｃ Ratio X ｃ / Y Ｐ２ It is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.0 or less, and particularly preferably 0.75 or less. ｃ / Y Ｐ２ When the above range is maintained, the soluble anionic polymer (P2) and the polyvalent cation (c) can be effectively bonded in the electrode active material layer.

[0152] When the electrode active material layer contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of polyvalent cation (c) X ｃRatio X ｃ / Y Ｐ２ This can be 0.010 to 3.0, 0.030 to 2.0, 0.045 to 1.0, 0.25 to 0.75, 0.45 to 0.75, or 0.60 to 0.75.

[0153] From the viewpoint of effectively bonding the polyvalent cation (c) with the anionic functional group, the polyvalent cation (c) preferably contains a metal ion, more preferably contains at least one selected from the group consisting of zinc ions, magnesium ions, aluminum ions, calcium ions, copper ions, iron ions, manganese ions, and chromium ions, and even more preferably contains a zinc ion.

[0154] From the viewpoint of improving the charge and discharge capacity of the electrode, the content of the electrode active material in the electrode active material layer is preferably 75% by mass or more, more preferably 85% by mass or more, and even more preferably 95% by mass or more. From the viewpoint of balancing with the content of other components, the content of the electrode active material in the electrode active material layer is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less. The content of the electrode active material in the electrode active material layer may be 75% by mass to 99% by mass, 85% by mass to 98% by mass, or 95% by mass to 97% by mass.

[0155] The content of the dispersible anionic polymer (P1) in the electrode active material layer is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 1.2% by mass or more. When the content of the dispersible anionic polymer (P1) is within the above range, the electrode active materials can be sufficiently bonded to each other, or to the electrode active materials and the current collector.

[0156] The content of the dispersible anionic polymer (P1) in the electrode active material layer is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less. When the content of the dispersible anionic polymer (P1) is within the above range, the content of the electrode active material in the electrode active material layer can be increased, and the charge and discharge capacity of the electrode can be improved.

[0157] The content of the dispersible anionic polymer (P1) in the electrode active material layer may be 0.5% to 5.0% by mass, 1.0% to 3.0% by mass, or 1.2% to 2.0% by mass.

[0158] When the electrode active material layer contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) in the electrode active material layer is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. When the content of the soluble anionic polymer (P2) is within the above range, a sufficient film of the soluble anionic polymer (P2) can be formed on the surface of the electrode active material, which contributes to improving the bonding strength between the electrode active materials themselves, or between the electrode active material and the current collector.

[0159] When the electrode active material layer contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) in the electrode active material layer is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less. When the content of the soluble anionic polymer (P2) is within the above range, the content of the electrode active material in the electrode active material layer can be increased, and the charge and discharge capacity of the electrode can be improved.

[0160] When the electrode active material layer contains a soluble anionic polymer (P2), the content of the soluble anionic polymer (P2) in the electrode active material layer may be 0.5% to 5.0% by mass, 1.0% to 3.0% by mass, or 1.2% to 2.0% by mass.

[0161] When the electrode active material layer contains a soluble anionic polymer (P2), the amount of anions Y contained in the soluble anionic polymer (P2) in the electrode active material layer. Ｐ２ The amount of anions Y contained in the dispersible anionic polymer (P1) relative to [the specified value]. Ｐ１ Ratio Y Ｐ１ / Y Ｐ２ A preferred range is Y in the electrode binder composition. Ｐ１ / Y Ｐ２ This is similar to the preferred range.

[0162] When the electrode active material layer contains a soluble anionic polymer (P2), the preferred range of the content of the soluble anionic polymer (P2) relative to 100 parts by mass of the content of the dispersible anionic polymer (P1) is the same as the preferred range of the content of the soluble anionic polymer (P2) in the electrode binder composition.

[0163] <Method for Manufacturing an Electrode> One embodiment of the present disclosure is a method for manufacturing an electrode, comprising: a mixing step of mixing an electrode active material, an aqueous medium, a dispersible anionic polymer (P1), and a polyvalent cationic substance (C) to obtain an electrode slurry; a coating step of applying the electrode slurry to a current collector; and a drying step of removing the aqueous medium from the electrode slurry applied to the current collector.

[0164] The electrode manufacturing method may include, if necessary, a cutting step in which a structure consisting of an electrode active material layer and a current collector (hereinafter also referred to as an electrode sheet), obtained by removing the aqueous medium from the electrode slurry in a drying step, is cut to a size and shape suitable for the size and shape of the battery, etc., or the electrode sheet may be used as an electrode as is without including a cutting step. The electrode manufacturing method may also include, if necessary, a pressing step in which the electrode sheet obtained in the drying step is pressed. The electrode manufacturing method may also include steps other than those described above, if necessary.

[0165] In the mixing step, it is preferable to further mix in a soluble anionic polymer (P2). In the mixing step, other components such as conductive additives, basic substances, and surfactants may be further mixed in. The method for carrying out the mixing step may be the same as that for producing the electrode slurry described above.

[0166] In the coating process, the method of applying the electrode slurry onto the current collector is not particularly limited and includes, for example, the reverse roll method, direct roll method, doctor blade method, knife method, extrusion method, curtain method, gravure method, bar method, dip method, squeeze method, etc.

[0167] When applying electrode slurry to both sides of a current collector, it may be applied sequentially to one side at a time, or to both sides simultaneously. The application of electrode slurry may be carried out continuously or intermittently. The amount of electrode slurry applied can be appropriately determined according to the design capacity of the battery, the composition of the electrode slurry, etc.

[0168] In the drying process, the method for removing the aqueous medium from the electrode slurry applied to the current collector is not particularly limited, and for example, hot air drying, reduced pressure drying, vacuum drying, (far) infrared drying, low-temperature air drying, or a combination thereof can be used.

[0169] In the drying process, when the electrode slurry is dried by heating, the drying temperature and drying time can be appropriately adjusted depending on the concentration of non-volatile components in the electrode slurry, the amount applied to the current collector, etc. The drying temperature is preferably 40°C to 350°C, and more preferably 60°C to 100°C from the viewpoint of productivity. The drying time is preferably 1 minute to 30 minutes.

[0170] The method of cutting the electrode sheet in the cutting process is not particularly limited and can be done using slits, lasers, wire cutters, cutters, die cutters, etc.

[0171] The method of pressing the electrode sheet in the pressing process is not particularly limited and may be carried out by a die press or a roll press. By pressing the electrode sheet, the electrode active material can be firmly bonded to the current collector, and the thickness of the electrode can be reduced, making the non-aqueous secondary battery smaller. When using the die press method, the pressing pressure is not particularly limited, but is 0.5 t / cm. ２ ~5 t / cm ２It is preferable to do so. When using the roll press method, the press load is not particularly limited, but is preferably 0.5 t / cm to 8 t / cm. When the press load is within the above range, the above effects due to pressing are easily obtained, and the decrease in the insertion and desorption capacity of charge carriers such as lithium ions into the electrode active material tends to be suppressed.

[0172] <Non-aqueous secondary battery> One embodiment of the present disclosure is a non-aqueous secondary battery equipped with the electrodes described above. Below, a lithium-ion secondary battery will be described as a preferred example of the non-aqueous secondary battery according to the present disclosure. However, the configuration of the non-aqueous secondary battery of the present disclosure is not limited to the example shown below.

[0173] A lithium-ion secondary battery has a configuration in which, for example, a positive electrode, a negative electrode, and an electrolyte are housed in an outer casing. The lithium-ion secondary battery may further include a separator placed between the positive electrode and the negative electrode, and may further include other components. The shape of the lithium-ion secondary battery is not particularly limited and may be coin-shaped, button-shaped, sheet-shaped, cylindrical, prismatic, flat, or the like.

[0174] [Positive and Negative Electrodes] The lithium-ion secondary battery of the present disclosure preferably has one or both of the positive and negative electrodes comprising a dispersible anionic polymer (P1) and a polyvalent cation (c), and optionally further comprising a soluble anionic polymer (P2). The lithium-ion secondary battery of the present disclosure preferably has the negative electrode comprising a dispersible anionic polymer (P1) and a polyvalent cation (c), and optionally further comprising a soluble anionic polymer (P2).

[0175] [Electrolyte] It is preferable to use a non-aqueous liquid with ionic conductivity as the electrolyte. Examples of electrolytes include solutions in which the electrolyte is dissolved in an organic solvent, and ionic liquids. From the viewpoint of obtaining a lithium-ion secondary battery with low manufacturing costs and low internal resistance, a solution in which the electrolyte is dissolved in an organic solvent is preferred as the electrolyte.

[0176] Alkali metal salts can be used as electrolytes, and can be appropriately selected depending on the type of electrode active material, etc. LiClO ４ LiBF６ LiPF ６ LiCF ３ SO ３ LiCF ３ CO ２ LiAsF ６ LiSbF ６ LiB １０ Cl １０ LiAlCl ４ , LiCl, LiBr, LiB(C ２ H ５ ) ４ CF ３ SO ３ Li, CH ３ SO ３ Li, LiCF ３ SO ３ LiC ４ F ９ SO ３ , Li(CF ３ SO ２ ) ２ Examples include nitrogen (N) and lithium aliphatic carboxylate. Other alkali metal salts can also be used as electrolytes.

[0177] Examples of organic solvents for dissolving electrolytes include carbonate ester compounds such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), and vinylene carbonate (VC), as well as carboxylic acid esters such as ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate. The organic solvent may be used alone or in combination of two or more. Preferably, the organic solvent contains two or more linear carbonate solvents.

[0178] The electrolyte may contain additives in addition to the above components. Examples of additives include nitrile compounds, sulfur-containing compounds, and boron-containing compounds. Examples of nitrile compounds include succinonitrile and acetonitrile. Examples of sulfur-containing compounds include compounds having a sulfonyl group, sulfonate group, or sultone structure, such as methyl ethyl sulfone and 1,3-propanesultone. Examples of boron-containing compounds include boric acid esters.

[0179] [Outer casing] The type of outer casing is not particularly limited and can be selected according to the application of the non-aqueous secondary battery. In one embodiment, the outer casing can be made of an aluminum laminate material consisting of aluminum foil and a resin film.

[0180] Hereinafter, an example of an embodiment of this disclosure will be specifically described with reference to the examples, but the embodiments are not limited to these examples.

[0181] In the following embodiments, a negative electrode for a lithium-ion secondary battery was fabricated as an example of an electrode according to the disclosure, and a lithium-ion secondary battery was fabricated as an example of a non-aqueous secondary battery according to the disclosure. Deionized water was used as the water.

[0182] (1) Preparation of Electrode Binder Composition A monomer emulsion was prepared by mixing the monomers shown in Table 1 in the amounts (parts by mass) shown in Table 1. Furthermore, an aqueous solution was prepared by dissolving the polymerization initiator in the amount (parts by mass) shown in Table 1 in water (50 parts by mass). Water (150 parts by mass) was placed in a separable flask equipped with a condenser, thermometer, stirrer and dropping funnel, and the temperature was raised to 80°C. The monomer emulsion and the aqueous solution of the polymerization initiator were continuously supplied to this separable flask over 3 hours while stirring at 80°C, thereby undergoing emulsion polymerization to obtain an emulsion. The obtained emulsion was cooled to 25°C. Subsequently, ammonia water (concentration: 25% by mass), water, and zinc oxide as a divalent cationic compound (examples only) were added to the emulsion in the amounts (parts by mass) shown in Table 1 to obtain the electrode binder composition. The amount of ammonia shown in Table 1 is the amount of ammonia contained in the ammonia water added to the emulsion. The amounts of water shown in Table 1 represent the total amount of water ultimately contained in the electrode binder composition.

[0183] The following components were used as polymerization initiators as shown in Table 1: Potassium persulfate 1.0 part by mass, Sodium formaldehyde sulfoxylate (Longalit SFS) 0.6 parts by mass, Tert-butyl peroxybenzoate 0.6 parts by mass, Tert-butyl hydroperoxide 1.8 parts by mass, Ascorbic acid 2.2 parts by mass.

[0184] Of the monomers shown in Table 1, acrylic acid, methacrylic acid, sodium p-styrenesulfonate, and polymerizable surfactants are monovalent anionic compounds, while itaconic acid is a divalent anionic compound.

[0185] The polymerizable surfactant shown in Table 1 is polyoxyethylene-1-(allyloxymethyl)alkyl ether sulfate ammonium salt represented by the following formula (1) (Daiichi Kogyo Seiyaku Co., Ltd., Aqualon KH-10, the structure of R and the value of n are not disclosed).

[0186]

[0187] (A Ｐ１(Calculation) Amount of anions per gram of dispersible anionic polymer (P1) A based on the amount of monomer used in the manufacture of the electrode binder composition. Ｐ１ The following was calculated: Specifically, the amount of anions Y of the monomer corresponding to the anionic compound. Ｐ１ (mol) is calculated using the following formula, and the obtained Y Ｐ１ From the value, A is calculated using the following formula. Ｐ１ The concentration (milligrams / g) was determined. The results are shown in Table 1.

[0188] Y Ｐ１ = Amount of acrylic acid / molecular weight (72) + Amount of methacrylic acid / molecular weight (86) + 2 × Amount of itaconic acid / molecular weight (130) + Amount of p-styrene sulfonate sodium / molecular weight (206) A Ｐ１ = 1000 × Y Ｐ１ / Total amount of all monomers

[0189] (X Ｃ / Y Ｐ１ (Calculation of) Based on the amount of monomer and zinc oxide used in the manufacture of the electrode binder composition, the amount of anions Y of the dispersible anionic polymer (P1) Ｐ１ The amount of cations X of the polyvalent cationic substance (C) relative to the given substance. Ｃ Ratio X Ｃ / Y Ｐ１ We calculated X using the following formula. Ｃ to Y Ｐ１ By dividing by X, Ｃ / Y Ｐ１ We calculated X. The results are shown in Table 1. Ｃ = 2 × amount of zinc oxide / molecular weight (81)

[0190] The amount of anions in polymerizable surfactants varies depending on the molecular weight, and A Ｐ１ Because the effect on the value of is small, as mentioned above, A Ｐ１ and X Ｃ / Y Ｐ１ This is not considered in the calculation. In other words, the maximum amount of anions in a polymerizable surfactant when the amount is constant is the value when the molecular weight of the structure represented by formula (1) is at its minimum value (243). Therefore, the maximum amount of anions in a polymerizable surfactant calculated based on the amounts shown in Table 1 is 0.007 mol (0.018 mmol / g).

[0191] (Measurement of glass transition point Tg of dispersible anionic polymer (P1)) An electrode binder composition was applied to a release PET (polyethylene terephthalate) film and dried at 160°C for 1 hour to form a polymer film with a thickness of 0.5 mm. A square test specimen measuring 2 mm in length and 2 mm in width was prepared using the polymer film released from the release PET film. The test specimen was sealed in an aluminum pan, and the glass transition point Tg of the dispersible anionic polymer (P1) was measured under the following conditions. The results are shown in Table 1. Test apparatus: EXSTAR DSC / SS7020 manufactured by Hitachi High-Tech Science Co., Ltd. Test atmosphere: Nitrogen gas atmosphere Heating rate: 10°C / min Temperature range: -40°C to 200°C Method for determining glass transition point Tg: The peak top temperature of the DDSC chart obtained as the temperature derivative of DSC was taken as the glass transition point Tg (°C) of the polymer.

[0192] (Measurement of Non-Volatile Content Concentration of Electrode Binder Composition) 1 g of the electrode binder composition was weighed onto a 5 cm diameter aluminum dish and dried at 1 atmosphere (1013 hPa) in a drying oven at 105°C for 1 hour while circulating air. The mass of the remaining components was then measured. The mass ratio (mass%) of the components remaining after drying to the mass (1 g) of the electrode binder composition before drying was calculated and defined as the non-volatile content concentration (mass%). The results are shown in Table 1.

[0193] (Measurement of particle size D50 of particles containing dispersible anionic polymer (P1)) The particle size D50 of particles in the electrode binder composition was measured by dynamic light scattering using NANOTRAC WAVE II. The particle size D50 measured here was defined as the particle size D50 of particles containing dispersible anionic polymer (P1). The results are shown in Table 1.

[0194]

[0195] (2) Preparation of anode slurry Anode slurry was obtained by mixing synthetic graphite (G49, manufactured by Jiangxi Zichen Technology Co., Ltd.) as the anode active material, the electrode binder composition obtained in the above step, and sodium carboxymethylcellulose (CMCNa) as a soluble anionic polymer (P2) with water. The degree of etherification of the sodium carboxymethylcellulose used here was 0.70, the weight-average molecular weight was 2 million, and it was added as a 2% by mass aqueous solution. Mixing was performed using a rotation-orbit mixer (ARE-310, manufactured by Thinky Co., Ltd.).

[0196] The amounts of each component and composition used were adjusted so that the content of the dispersible anionic polymer (P1) in the solid content of the negative electrode slurry was 1.5% by mass, the content of the soluble anionic polymer (P2) was 1.2% by mass, and the solid content concentration was 55% by mass. The solid content of the negative electrode slurry consists of the negative electrode active material, the dispersible anionic polymer (P1), components derived from the polymer initiator used in the production of the electrode binder composition, a polyvalent cationic substance (C), and the soluble anionic polymer (P2).

[0197] Amount of anions Y contained in the soluble anionic polymer (P2) in the negative electrode slurry. Ｐ２ The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ２ , and the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of anions Y contained in the dispersible anionic polymer (P1) relative to [the specified value]. Ｐ１ Ratio Y Ｐ１ / Y Ｐ２ This is shown in Table 2.

[0198] Here, X Ｃ / Y Ｐ２ and Y Ｐ１ / Y Ｐ２ This is calculated based on the degree of etherification E of CMCNa. In CMCNa with a degree of etherification E, an average of E hydroxyl groups (0 ≤ E ≤ 3, where E may be a decimal) of the three hydroxyl groups contained in one structural unit of CMC are CH ２It is replaced with COONa. Therefore, the average formula weight of one structural unit of this CMCNa is 162 + 80 × E. And the amount of anion A per gram of CMCNa is Ｐ２ The concentration is 1000 × E / (162 + 80 × E) [ mmol / g].

[0199] On the other hand, the amount of anions A per gram of the dispersible anionic polymer (P1) Ｐ１ This is determined as shown in Table 1. The mass ratio of the content of dispersible anionic polymer (P1) to the content of soluble anionic polymer (P2) in the negative electrode slurry is 1.5:1.2. Therefore, Y Ｐ１ / Y Ｐ２ (A Ｐ１ ×1.5) / (A Ｐ２ It can be calculated by multiplying by 1.2). Also, X Ｃ / Y Ｐ１ Since this is obtained from Table 1, X Ｃ / Y Ｐ２ This is also required.

[0200] (3) Manufacturing of non-aqueous secondary batteries Using the negative electrode slurry obtained by the above process, a lithium-ion secondary battery, which is a non-aqueous secondary battery, was manufactured by the method shown below.

[0201] A copper foil with a thickness of 10 μm was prepared as the negative electrode current collector. The negative electrode slurry obtained by the above process was applied to both sides of the negative electrode current collector by the direct roll method. The amount of negative electrode slurry applied to the negative electrode current collector was adjusted so that the thickness of the negative electrode active material layer after the roll press treatment described later was 170 μm per side. The negative electrode slurry applied on the negative electrode current collector was dried at 90°C for 10 minutes, and then pressed using a roll press (manufactured by Sankmetal Co., Ltd., press load 8 t / cm, roll width 7 cm) by the roll press method to obtain a negative electrode sheet having a negative electrode active material layer on both sides of the negative electrode current collector. The obtained negative electrode sheet was cut into a rectangle with a length of 52 mm and a width of 42 mm, and conductive tabs were attached to make it a negative electrode.

[0202] The amount of anions Y contained in the dispersible anionic polymer (P1) in the negative electrode produced in each example and comparative example. Ｐ２ The amount of polyvalent cation (c) Xｃ Ratio X ｃ / Y Ｐ１ The amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of polyvalent cation (c) X ｃ Ratio X ｃ / Y Ｐ２ , and the amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of anions Y contained in the dispersible anionic polymer (P1) relative to [the specified value]. Ｐ１ Ratio Y Ｐ１ / Y Ｐ２ This is shown in Table 2.

[0203] LiNi as a positive electrode active material ０．６ Mn ０．２ Co ０．２ O ２ (94 parts by mass) was mixed with acetylene black (3 parts by mass) as a conductive additive and polyvinylidene fluoride (3 parts by mass) as a binder to obtain a mixture. N-methylpyrrolidone (50 parts by mass) was added to the obtained mixture and mixed further to obtain a positive electrode slurry.

[0204] A 15 μm thick aluminum foil was prepared as the positive electrode current collector. The positive electrode slurry was applied to both sides of the positive electrode current collector using the direct roll method. The amount of positive electrode slurry applied to the positive electrode current collector was adjusted so that the thickness after the roll press treatment described later was 125 μm per side.

[0205] The positive electrode slurry applied to the positive electrode current collector was dried at 120°C for 5 minutes, and then pressed using a roll press (manufactured by Sankmetal Co., Ltd., press load 4 t / cm, roll width 7 cm) by the roll press method to obtain a positive electrode sheet having positive electrode active material layers on both sides of the positive electrode current collector. The obtained positive electrode sheet was cut into a rectangle measuring 50 mm in length and 40 mm in width, and conductive tabs were attached to form the positive electrode.

[0206] A separator made of a porous polyolefin film (polyethylene, 25 μm thick) was interposed between the positive and negative electrodes, and the positive electrode active material layer and the negative electrode active material layer were laminated so that they faced each other. These were then housed in an outer casing (battery pack) made of aluminum laminate material. Subsequently, an electrolyte solution was injected into the outer casing, vacuum impregnation was performed, and the battery was packed using a vacuum heat sealer to obtain a lithium-ion secondary battery.

[0207] The electrolyte is a mixed solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of EC:EMC:DEC = 30:50:20, to which LiPF is added at a concentration of 1.0 mol / L. ６ A mixture of 99 parts by mass of a solution containing dissolved material and 1 part by mass of vinylene carbonate was used.

[0208] (4) Evaluation of non-aqueous secondary batteries The lithium-ion secondary batteries produced in each example and comparative example were evaluated for their internal resistance (DCR) and discharge capacity retention rate after 500 cycles using the methods described below. The evaluation results are shown in Table 2.

[0209] (Internal Resistance (DCR)) Under conditions of 25°C, the following procedure was performed. First, the charge state was set to 50% of the initial capacity (SOC 50%) at 0.2C. Then, discharge was performed for 60 seconds at current values ​​of 0.2C, 0.5C, 1C, and 2C. The internal resistance DCR (Ω) at SOC 50% was determined from the relationship between these four current values ​​(values ​​over 10 seconds) and voltage.

[0210] (Retention rate of discharge capacity after 500 cycles) Under conditions of 25°C, charging and discharging were performed with each cycle consisting of the following steps (i) to (iv). The time integral of the current in steps (i) and (ii) was defined as the charging capacity, and the time integral of the current in step (iv) was defined as the discharge capacity. The discharge capacity after the first cycle and the discharge capacity after the 500th cycle were measured, and the retention rate of discharge capacity after 500 cycles was calculated using the following formula: Retention rate of discharge capacity after 500 cycles (%) = 100 × (Discharge capacity at 500th cycle / Discharge capacity at 1st cycle)

[0211] (i) Charge at a current of 1C until the voltage reaches 4.2V (constant current (CC) charging) (ii) Charge at a voltage of 4.2V until the current reaches 0.05C (constant voltage (CV) charging) (iii) Let stand for 30 minutes (iv) Discharge at a current of 1C until the voltage reaches 2.75V (constant current (CC) discharge)

[0212]

[0213] As shown in Table 2, the non-aqueous secondary batteries of Examples 1 to 11, prepared using electrode binder compositions, electrode slurries, or electrodes containing a dispersible anionic polymer (P1) and a polyvalent cationic substance (C), all exhibited high discharge capacity retention after 500 cycles and minimal capacity degradation during repeated charge-discharge cycles. Furthermore, their internal resistance values ​​were also favorable.

[0214] Comparative Examples 1 and 2, which were prepared using electrode binder compositions, electrode slurries, or electrodes that did not contain polyvalent cationic substances (C), all had low discharge capacity retention rates after 500 cycles, and the capacity degradation after repeated charging and discharging was greater than that of the Examples.

[0215] From the above results, it was found that the present disclosure provides an electrode binder composition, an electrode slurry, and an electrode that can produce a non-aqueous secondary battery with minimal capacity degradation when repeatedly charged and discharged. Furthermore, it was found that the present disclosure can produce a non-aqueous secondary battery with minimal capacity degradation when repeatedly charged and discharged.

[0216] The disclosure of Japanese Patent Application No. 2024-193909 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. An electrode binder composition comprising: an aqueous medium; a dispersible anionic polymer (P1) having anionic functional groups and dispersed in the aqueous medium; and a polyvalent cationic substance (C) capable of forming polyvalent cations (c) in the aqueous medium.

2. Amount of anions per gram of the dispersible anionic polymer (P1) A Ｐ１ The electrode binder composition according to claim 1, wherein the amount is 0.30 mmol / g or more.

3. Amount of anions Y contained in the dispersible anionic polymer (P1) Ｐ１ The amount of cations X of the polyvalent cationic substance (C) Ｃ Ratio X Ｃ / Y Ｐ１ The electrode binder composition according to claim 1, wherein the ratio is 0.050 or more and 5.0 or less.

4. The electrode binder composition according to claim 1, wherein the polyvalent cationic substance (C) comprises at least one selected from the group consisting of metals and metal compounds.

5. The electrode binder composition according to claim 1, further comprising a soluble anionic polymer (P2) having an anionic functional group and soluble in the aqueous medium.

6. Amount of anions per 1 g of the soluble anionic polymer (P2) A Ｐ２ The electrode binder composition according to claim 5, wherein the amount is 1.0 mmol / g or more.

7. The amount of anions Y contained in the soluble anionic polymer (P2) Ｐ２ The amount of cations X of the polyvalent cationic substance (C) relative to Ｃ Ratio X Ｃ / Y Ｐ２ The electrode binder composition according to claim 5, wherein the ratio is 0.010 or more and 3.0 or less.

8. An electrode slurry comprising: an aqueous medium; an electrode active material; a dispersible anionic polymer (P1) having anionic functional groups and dispersed in the aqueous medium; and a polyvalent cationic substance (C) capable of forming polyvalent cations (c) in the aqueous medium.

9. The electrode slurry according to claim 8, further comprising a soluble anionic polymer (P2) having an anionic functional group and soluble in the aqueous medium.

10. An electrode having a current collector and an electrode active material layer, wherein the electrode active material layer comprises an electrode active material, a dispersible anionic polymer (P1) having anionic functional groups and dispersed in an aqueous medium, and a polyvalent cation (c).

11. The electrode according to claim 10, wherein the electrode active material layer further comprises a soluble anionic polymer (P2) having anionic functional groups and soluble in an aqueous medium.

12. A non-aqueous secondary battery comprising the electrode according to claim 10 or claim 11.

13. A method for manufacturing an electrode, comprising: a mixing step of mixing an electrode active material, an aqueous medium, a dispersible anionic polymer (P1) having an anionic functional group and dispersed in the aqueous medium, and a polyvalent cationic substance (C) capable of forming a polyvalent cation (c) in the aqueous medium to obtain an electrode slurry; a coating step of applying the electrode slurry to a current collector; and a drying step of removing the aqueous medium from the electrode slurry applied to the current collector.

14. The method for producing an electrode according to claim 13, wherein in the mixing step, a soluble anionic polymer (P2) having anionic functional groups and soluble in the aqueous medium is further mixed.

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