Nonaqueous electrolyte secondary battery and separator for nonaqueous electrolyte secondary battery

Abstract

The disclosed nonaqueous electrolyte secondary battery includes a positive electrode (11), a negative electrode (12), a separator (50) disposed between the positive electrode (11) and the negative electrode (12), a nonaqueous electrolyte, and a separator (53) disposed in at least one region selected from the group consisting of a region between the positive electrode (11) and the separator (50) and a region between the negative electrode (12) and the separator (50). The negative electrode (12) is a negative electrode in which a metal, which is a negative electrode active material, is precipitated during charging and the metal is dissolved during discharging. The spacer (53) contains a resin and a filler. The resin contains a cellulose compound.

Description

Technical Field

[0001] The present disclosure relates to a nonaqueous electrolyte secondary battery and a separator for the nonaqueous electrolyte secondary battery. Background Art

[0002] As a type of non-aqueous electrolyte secondary battery, a lithium secondary battery (lithium metal secondary battery) is known. In a lithium secondary battery, lithium metal is deposited at the negative electrode during charging and dissolves in the non-aqueous electrolyte during discharge. Various solutions have been proposed for lithium secondary batteries.

[0003] Claim 1 of Patent Document 1 (International Publication No. 2020 / 066254) states: "A lithium secondary battery comprising: a positive electrode comprising a positive electrode collector and a positive electrode composite material layer containing a positive electrode active material; a negative electrode comprising a negative electrode collector opposite to the positive electrode; a separator arranged between the positive electrode and the negative electrode; and a non-aqueous electrolyte with lithium ion conductivity, wherein the positive electrode active material comprises a composite oxide comprising lithium and a metal M other than lithium, the metal M comprising at least a transition metal, lithium metal is deposited in the negative electrode during charging, and the lithium metal is dissolved from the negative electrode during discharging, the first length of the positive electrode collector in the first direction D1 is smaller than the second length in the second direction D2 intersecting the first direction, a spacer is provided between the positive electrode and the separator in such a manner as to form a space for accommodating the lithium metal between the positive electrode and the negative electrode, and a straight line SL can be drawn along the first direction D1 in such a manner as to pass through the spacer at more than three positions."

[0004] Patent Document 2 (Japanese Patent No. 7017869) states in claim 1: "A wound body, which is a wound body of a separator, the separator having a thermoplastic polymer coating layer coated on at least one side of a substrate, the puncture strength of the side of the wound body in an area less than 1 cm from the innermost layer of the wound separator is 10N or more and 100N or less, the substrate is a polyolefin porous substrate containing a polyolefin resin as a main component, the thermoplastic polymer coating layer contains at least one (i) a glass transition point (Tg) or a melting point (Tm) of 20°C or more and 100°C or less. Thermoplastic polymers, and / or (ii) at least two thermoplastic polymers having at least two glass transition temperatures as a whole, at least one of the glass transition temperatures being in a region below 40°C and at least one of the glass transition temperatures being in a region above 40°C, wherein the thermoplastic polymer comprises at least one member selected from the group consisting of a fluorine-containing resin, a copolymer containing a fluorine-containing resin, a diene polymer, a copolymer containing a diene polymer, a hydrogenated diene polymer, an acrylic polymer, a copolymer containing an acrylic polymer, and a hydrogenated acrylic polymer.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2020 / 066254

[0008] Patent Document 2: Japanese Patent No. 7017869 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] Currently, there is a demand for further improvement in the characteristics of non-aqueous electrolyte secondary batteries. One of the objects of the present disclosure is to provide a non-aqueous electrolyte secondary battery having high initial characteristics and cycle characteristics.

[0011] Solutions for solving problems

[0012] One embodiment of the present disclosure relates to a nonaqueous electrolyte secondary battery. The nonaqueous electrolyte secondary battery comprises: a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, a nonaqueous electrolyte, and a separator, wherein the separator is disposed in at least one region selected from the group consisting of a region between the positive electrode and the separator and a region between the negative electrode and the separator. The negative electrode is a negative electrode in which a metal as a negative electrode active material is deposited during charge and dissolved during discharge. The separator contains a resin and a filler, and the resin contains a cellulose-based compound.

[0013] Another embodiment of the present disclosure relates to a separator for a non-aqueous electrolyte secondary battery, comprising a substrate and a spacer formed on the substrate, wherein the spacer contains a resin and a filler, and the resin contains a cellulose compound.

[0014] Effects of the Invention

[0015] According to the present disclosure, a nonaqueous electrolyte secondary battery having high initial characteristics and cycle characteristics, and a separator used therefor can be obtained.

[0016] The novel features of the present invention are described in the appended claims, but the present invention, both in terms of configuration and content, together with other objects and features of the present invention, should be more fully understood from the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a longitudinal cross-sectional view schematically showing an example of a non-aqueous electrolyte secondary battery according to an embodiment of the present disclosure.

[0018] Figure 2 It is schematically shown Figure 1A cross-sectional view of a portion of a lithium secondary battery is shown.

[0019] Figure 3 It is a top view showing an example of a spacer pattern.

[0020] Figure 4 It is a plan view showing another example of the spacer pattern.

[0021] Figure 5 It is a plan view showing another example of the spacer pattern. DETAILED DESCRIPTION

[0022] Hereinafter, the embodiments of the present disclosure will be described with examples, but the embodiments of the present disclosure are not limited to the examples described below. In the following description, specific numerical values ​​and / or materials are sometimes exemplified, but as long as the invention of the present disclosure can be implemented, other numerical values ​​and / or materials can also be applied. In this specification, the description of "numerical value A to numerical value B" includes numerical value A and numerical value B, which can be replaced by "above numerical value A and below numerical value B". In the following description, when the lower limit and upper limit of numerical values ​​related to specific physical properties and / or conditions are exemplified, as long as the lower limit does not become above the upper limit, any lower limit of the example can be arbitrarily combined with any upper limit of the example.

[0023] (Non-aqueous electrolyte secondary battery)

[0024] Hereinafter, the non-aqueous electrolyte secondary battery of this embodiment may be referred to as a "non-aqueous electrolyte secondary battery (B)" or "secondary battery (B)". Secondary battery (B) includes: a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, a non-aqueous electrolyte, and a separator, wherein the separator is arranged in at least one region selected from the group consisting of a region between the positive electrode and the separator, and a region between the negative electrode and the separator. The negative electrode is a negative electrode in which a metal as a negative electrode active material is precipitated during charging and the metal is dissolved during discharge. The separator contains a resin and a filler. The resin contains a cellulose compound.

[0025] When using a negative electrode in which metal (negative electrode active material) is precipitated during charging, a spacer has always been used to ensure space for metal precipitation. In the secondary battery (B), a spacer is used to ensure space between the positive electrode and the negative electrode. Therefore, when charging and discharging are repeated, the electrode group can be suppressed from expanding. As a result, the reduction in cycle characteristics can be suppressed. It should be noted that if the electrode group expands, internal short circuits caused by the precipitated metal (negative electrode active material) are likely to occur. For this reason, the cycle characteristics become easily reduced.

[0026] Currently, there is a demand for further improvement in the characteristics of non-aqueous electrolyte secondary batteries. The inventors of this application conducted research and found that using a separator having the above-mentioned structure can produce a non-aqueous electrolyte secondary battery with both high initial performance and high cycle performance. The present disclosure is based on this new insight.

[0027] The metal (negative electrode active material) deposited during charging may be at least one selected from the group consisting of lithium and sodium. The metal deposited during charging may contain lithium. The metal deposited during charging may be lithium metal. Lithium metal may also contain trace amounts of other metal elements.

[0028] Lithium secondary batteries in which lithium metal is deposited on the negative electrode during charging are also called lithium metal secondary batteries. Lithium metal is deposited on the negative electrode of a lithium secondary battery during charging and dissolves during discharge. The negative electrode has at least a negative electrode current collector, on which the lithium metal is deposited. Hereinafter, a lithium secondary battery (B) may be referred to as a "lithium secondary battery (LB)."

[0029] In a lithium secondary battery (LB), more than 70% of the rated capacity, for example, is manifested by the precipitation and dissolution of lithium metal. The migration of electrons in the negative electrode during charging and discharging is mainly based on the precipitation and dissolution of lithium metal in the negative electrode. Specifically, 70% to 100% (e.g., 80% to 100% and / or 90% to 100%) of the migration of electrons in the negative electrode during charging and discharging (current in other viewpoints) is based on the precipitation and dissolution of lithium metal.

[0030] The content Cc of the cellulose compound in the resin contained in the spacer can be 50% by volume or more, 70% by volume or more, or 90% by volume or more, or can be 100% by volume or less, 80% by volume or less, or 60% by volume or less. By setting the content Cc to 50% by volume or more, a secondary battery (B) having particularly high initial characteristics and cycle characteristics can be obtained. The content Cc can be 100% by volume. That is, the resin of the spacer can also be composed solely of a cellulose compound.

[0031] The cellulose compound is at least one selected from the group consisting of cellulose and cellulose derivatives. The cellulose compound contained in the spacer may be cellulose, a cellulose derivative, or a mixture of cellulose and a cellulose derivative.

[0032] Cellulose derivatives are polymers with cellulose as their basic skeleton. Examples of cellulose derivatives include cellulose in which a portion of the cellulose has been substituted with a substituent different from that portion. Examples of cellulose derivatives include alkyl cellulose, carboxymethyl cellulose, nitrocellulose, and acetyl cellulose. Examples of alkyl cellulose include methyl cellulose and ethyl cellulose.

[0033] The cellulose-based compound may contain at least one selected from the group consisting of methyl cellulose, ethyl cellulose, and carboxymethyl cellulose, or may be at least one of these.

[0034] The resin contained in the spacer may contain other resins besides the cellulose compound. Examples of such other resins include fluorine-containing resins, acrylic resins, urethane resins, polyimide resins, conjugated diene polymers, polyvinyl alcohol resins, and polyvinyl pyrrolidone resins.

[0035] The content Cr of the resin in the spacer can be 30% by volume or more, 40% by volume or more, or 50% by volume or more, and can be 90% by volume or less, 80% by volume or less, or 60% by volume or less. By setting the content Cr to 30% by volume or more, the formation of pores in the spacer layer can be suppressed, thereby suppressing the precipitation of lithium in the pores in the spacer layer during charging, and improving the capacity retention rate.

[0036] The content Cf of the filler in the spacer may be 10% by volume or more, 20% by volume or more, or 40% by volume or more, and may be 70% by volume or less, 60% by volume or less, or 50% by volume or less.

[0037] The filler contained in the spacer is not particularly limited. The filler can be an insulating filler. The filler can be an inorganic filler (inorganic particles), an organic filler (organic particles), or a mixture thereof. Examples of filler materials include oxides, nitrides, carbides, etc. Examples of oxides include aluminum oxide (Alumina), magnesium oxide, titanium oxide, zirconium oxide, silicon oxide, etc. Examples of nitrides include silicon nitride, aluminum nitride, titanium nitride, etc. Examples of carbides include silicon carbide, etc.

[0038] The shape of the filler (particles) may be spherical or other than a spherical shape. The average particle size of the filler is not particularly limited and may be 0.1 μm or more, 0.3 μm or more, 0.4 μm or more or 0.5 μm or more, or may be 10 μm or less, 5 μm or less or 4 μm or less. In addition, the filler may also contain two or more fillers with different average particle sizes. The average particle size can be measured using the following method. First, a cross section of the spacer is photographed with an electron microscope to obtain an image of the cross section. Then, image processing such as binarization is performed on the image and the portion of the particle is determined. Next, the diameter of a circle having the same area as the cross-sectional area of ​​each particle is determined (equivalent circle diameter), and the arithmetic mean of the obtained equivalent circle diameters can be used as the average particle size. The arithmetic mean can be obtained from, for example, 20 particles. It should be noted that the average particle size of other particles contained in the electrode plate and separator can also be obtained using the same method.

[0039] The glass transition point Tg of the resin contained in the spacer may be 100°C or higher, 120°C or higher, or 130°C or higher. The upper limit of the glass transition point Tg is not particularly limited and may be 300°C or lower. By setting the glass transition point Tg to 100°C or higher, degradation of the spacer can be suppressed, and cycle characteristics can be improved.

[0040] The compressive strength of the resin contained in the spacer can be 90N / mm 2 Above, 140N / mm 2 Above or 190N / mm 2 The upper limit of the compressive strength is not particularly limited and can be 900N / mm 2 By setting the compressive strength to 90N / mm 2 The above can suppress the compression of the spacer and improve the cycle characteristics. The compressive strength can be measured according to JIS (Japanese Industrial Standard) K7181. Specifically, a test piece with a short side of 4 mm, a long side of 10 mm, and a height of 10 mm is clamped between two parallel plates and a load is applied to measure the compressive strength.

[0041] The spacer may be formed on at least one member selected from the group consisting of the positive electrode, the negative electrode, and the separator. The spacer may be formed on the positive electrode, the negative electrode, or the separator. From the perspective of adhesion, the spacer is preferably formed on the separator.

[0042] Depending on the form of the secondary battery (B), the spacer may be formed only on one side of the at least one component or on both sides. When the spacer is formed on the positive electrode, the spacer may be formed on at least one of the two main surfaces of the positive electrode that is opposite to the negative electrode. When the spacer is formed on the negative electrode, the spacer may be formed on the main surface of the two main surfaces of the negative electrode that is opposite to the positive electrode. When the spacer is formed on the separator, the spacer may be formed on the main surface of the positive electrode side of the separator or on the main surface of the negative electrode side of the separator.

[0043] The spacer is not particularly limited as long as it forms a space in at least one region selected from the group consisting of the region between the positive electrode and the separator and the region between the negative electrode and the separator. The spacer may include at least one selected from the group consisting of linear protrusions and dot-shaped protrusions, or may be at least one of these.

[0044] The spacer may also include linear protrusions arranged in a grid-like pattern. The grid-like pattern may be a pattern combining polygons (triangles, quadrilaterals, hexagons, etc.). For example, the grid-like pattern may be a honeycomb pattern. The spacer may also include multiple linear protrusions arranged in a stripe pattern. The spacer may also include multiple dot-like protrusions regularly arranged at regular intervals.

[0045] The shape of the cross section of the linear projection (a cross section perpendicular to the direction in which the linear projection extends) is not particularly limited and may be rectangular, trapezoidal, or semicircular.

[0046] In a component having a spacer, the ratio Rs of the area of ​​the spacer to the area of ​​the surface having the spacer may be less than 30%, less than 20%, less than 10%, or less than 5%. The ratio Rs may be greater than 1%, greater than 3%, or greater than 5%. When the spacer is formed on a single surface of the separator, the ratio of the area of ​​the spacer to the area of ​​the single surface may be within the range exemplified above regarding the ratio Rs. For example, when the spacer is formed on a single surface of the separator, the ratio of the area of ​​the spacer to the area of ​​the single surface may be less than 30%.

[0047] The average height Hs of the spacers may be greater than or equal to 10 μm or greater than 20 μm, or less than or equal to 100 μm, less than or equal to 50 μm, less than or equal to 40 μm, or less than or equal to 30 μm. It should be noted that the height of the spacers may be substantially constant so that the spacing between the plates formed by the spacers is substantially constant.

[0048] The average height Hs of the spacer can be measured using the following method. First, use an electron microscope to photograph a cross-section of a component (e.g., a separator) formed with a spacer in the thickness direction to obtain an image of the cross-section. At this time, multiple images are obtained as needed. Then, in the image, any five positions in the spacer are selected and the height of the spacer at these positions is measured. Then, the heights of the five measured positions are arithmetic averaged, and the obtained average value is used as the average height Hs.

[0049] The spacer may also include a non-porous structure that is not permeable to ions of the metal (e.g., lithium ions) that is the negative electrode active material. Such a spacer can be realized by forming it under conditions where it does not become porous when forming the spacer. The method for forming a spacer having a non-porous structure is not particularly limited, and a known method can be used. For example, a spacer having a non-porous structure can also be formed by printing the constituent materials of the above-mentioned spacer in the form of ink on a separator. It should be noted that, in this specification, "lithium ions will not permeate" means that the amount that will not permeate and affect the characteristics and / or shape of the battery, including the case where an amount of lithium ions that is considered to be substantially non-permeable migrates within the spacer.

[0050] The manufacturing method of the secondary battery (B) is not particularly limited except for using the above-mentioned separator. The secondary battery (B) can also be manufactured using the same manufacturing method as the known manufacturing method. The secondary battery (B) can be manufactured by enclosing an electrode group including a positive electrode, a negative electrode and a separator and a non-aqueous electrolyte in an outer shell.

[0051] (Separator)

[0052] Hereinafter, the separator of this embodiment may be referred to as "separator (S)". Separator (S) is a separator for non-aqueous electrolyte secondary batteries. Separator (S) includes a substrate and a spacer formed on the substrate. The spacer contains a resin and a filler. The resin contains a cellulose compound.

[0053] The separator (S) can use the same separators as those described for the secondary battery (B). The matters described for the separator (B) can be applied to the separator (S), so repeated descriptions may be omitted. The matters described for the separator (S) can also be applied to the secondary battery (B). In other words, the separator (S) can be used as both a separator (base material) and a spacer for the secondary battery (B).

[0054] The content of the cellulose compound in the resin contained in the spacer can be 50% by volume or more. The resin contained in the spacer can be a cellulose compound. The cellulose compound can include at least one selected from the group consisting of methyl cellulose, ethyl cellulose, and carboxymethyl cellulose, or at least one of these. The content of the resin in the spacer can be 30% by volume or more.

[0055] (Base material of separator)

[0056] The base material of the separator uses a sheet that can be used as a separator for a non-aqueous electrolyte secondary battery. The base material may consist solely of a base material layer. Alternatively, the base material may include a base material layer and a composite material layer formed on the base material layer. The composite material layer contains a polymer and inorganic particles. When the base material includes a base material layer and a composite material layer, the separator may be arranged so that the composite material layer is opposite to the positive electrode or so that the composite material layer is opposite to the negative electrode. When the base material includes a base material layer and a composite material layer, the spacer may be formed on the base material layer or on the composite material layer. By forming the spacer on the composite material layer, the effect of suppressing the thermal shrinkage of the base material layer becomes particularly high.

[0057] When the temperature of an electrode assembly consisting of a positive electrode, a negative electrode, and a separator rises excessively, the substrate layer shrinks, which can easily cause a short circuit between the positive and negative electrodes, leading to a further increase in the temperature of the electrode assembly. By laminating the composite material layer on the substrate layer, shrinkage of the substrate layer when the temperature of the electrode assembly rises can be suppressed. As a result, further temperature increases in the electrode assembly can be suppressed.

[0058] The substrate layer uses a porous sheet with ion permeability and insulation. Examples of porous sheets include porous membranes, woven fabrics, non-woven fabrics, etc. The material of the substrate layer is not particularly limited and can be a polymer material. Examples of polymer materials include polyolefin resins, polyamide resins, cellulose, etc. Examples of polyolefin resins include polyethylene, polypropylene, and copolymers of ethylene and propylene. The substrate layer may also contain additives as needed. As additives, inorganic fillers, etc. can be listed. The substrate layer can use a sheet used as a separator for a non-aqueous electrolyte secondary battery (e.g., a lithium secondary battery).

[0059] The composite material layer includes a polymer (hereinafter sometimes referred to as "polymer (PL)") and inorganic particles. The inorganic particles may also include first particles and / or second particles. The first particles are particles of a lithium-containing phosphate. The second particles are particles other than the first particles. The composite material layer is a layer that allows lithium ions to pass through.

[0060] The phosphate constituting the first particles may be at least one selected from the group consisting of lithium phosphate (Li3PO4), dilithium hydrogen phosphate (Li2HPO4), and lithium dihydrogen phosphate (LiH2PO4). Of these, lithium phosphate is preferred because it is highly effective in suppressing heat generation during abnormal conditions of the battery.

[0061] A preferred example of the second particles (inorganic particles) is particles composed of an insulating inorganic compound that does not melt or decompose when the battery is abnormally heated. The second particles can be inorganic particles commonly used as inorganic fillers. Examples of materials for the second particles include aluminum oxide, boehmite, talc, titanium oxide, magnesium oxide, and silicon oxide.

[0062] The polymer (PL) is preferably a polymer having a higher heat resistance than the main component of the separator substrate layer. The polymer (PL) may include at least one selected from the group consisting of aromatic polyamides, aromatic polyimides, and aromatic polyamide-imides, or may be at least one of these. These are known to be polymers with high heat resistance. From the viewpoint of heat resistance, aromatic polyamides (wholly aromatic polyamides) are preferred.

[0063] The inorganic particles may include the aforementioned first particles and second particles other than phosphate. In this case, the composite material layer may include a first layer containing the first particles and a second layer containing the second particles. This configuration can significantly enhance the effect of suppressing excessive temperature increases in the electrode assembly. It should be noted that the composite material layer may consist solely of the first layer or the second layer.

[0064] The first layer and the second layer can be stacked on the main surface of the positive electrode side of the two main surfaces of the substrate layer, can be formed on the main surface of the negative electrode side, or can be formed on different main surfaces. For example, the separator and the spacer can have a stacked structure of substrate layer / first layer / second layer / spacer, substrate layer / second layer / first layer / spacer, first layer / second layer / substrate layer / spacer, or second layer / first layer / substrate layer / spacer. Alternatively, the first layer and the second layer can be arranged on different main surfaces of the substrate layer. For example, the separator and the spacer can have a stacked structure of first layer / substrate layer / second layer / spacer or second layer / substrate layer / first layer / spacer.

[0065] The thickness of the substrate is not particularly limited and may be 5 μm or more or 10 μm or more, and may be 50 μm or less or 40 μm or less. When the substrate comprises a substrate layer and a composite material layer, the substrate layer may be 5 μm or more or 10 μm or more, and may be 50 μm or less or 40 μm or less.

[0066] (Method for Forming Spacer)

[0067] The method for forming the spacer is not particularly limited, and the spacer can be formed by the following method. First, a coating liquid is prepared by mixing the components of the spacer and a liquid medium (dispersion medium). Then, the coating liquid is applied to the portion where the spacer is to be formed, and then dried. In this manner, a spacer can be formed. The liquid medium used in the formation of the coating liquid is not particularly limited. Examples of liquid media include organic solvents (such as N-methyl-2-pyrrolidone). The coating liquid can be applied using a dispenser, etc., or using a known printing method such as gravure printing, inkjet printing, and screen printing. In addition, drying can be performed using known methods such as heating-based drying and / or natural drying. As described above, a separator can be obtained.

[0068] When the separator comprises a substrate layer and a composite material layer, it can be produced by the following method. First, prepare the substrate layer. A commercially available substrate layer can be used. Next, form the composite material layer on the substrate layer.

[0069] The method for forming the composite material layer is not particularly limited and can be formed by the following method. First, a coating liquid is formed by mixing the components of the composite material layer with a liquid medium (dispersion medium). Then, the coating liquid is applied to the substrate layer to form a coating film, and the coating film is dried. In this way, a composite material layer can be formed. The liquid medium used in the formation of the coating liquid is not particularly limited. Examples of the liquid medium include organic solvents (such as N-methyl-2-pyrrolidone).

[0070] The steps in forming the composite material layer are not particularly limited, and known methods can be applied. For example, the coating liquid can be applied by known methods such as a rod coater. In addition, drying can be performed by known methods such as heating and / or natural drying.

[0071] Hereinafter, examples of each component of the secondary battery (B) will be described in detail. It should be noted that the components described below are examples, and the components of the secondary battery (B) of this embodiment are not limited to the following components. Components other than the characteristic parts of the secondary battery (B) of this embodiment can use known components. Hereinafter, the case where the secondary battery (B) is a lithium secondary battery (lithium secondary battery (LB)) will be mainly described. In the case where the secondary battery (B) is a battery other than a lithium secondary battery, the positive and negative electrodes that conform to the battery can be used. The separators and spacers have been described, so repeated descriptions are omitted.

[0072] The shape of the secondary battery (B) is not particularly limited. Examples of the shape of the secondary battery (B) include cylindrical, coin, square, sheet, and flat shapes.

[0073] The negative electrode is arranged so as to face the positive electrode. The separator is arranged between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator can be wound so as to arrange the separator between the positive electrode and the negative electrode. When forming a wound electrode group, a strip-shaped positive electrode, a strip-shaped negative electrode, and a strip-shaped separator are used. Alternatively, the positive electrode, the negative electrode, and the separator can be stacked. For example, a flat positive electrode, a flat negative electrode, and a flat separator can be stacked. That is, the electrode group can be a wound electrode group or a stacked electrode group.

[0074] (negative electrode)

[0075] The negative electrode includes a negative electrode collector. In a lithium secondary battery (LB), lithium metal is deposited on the negative electrode collector due to charging. More specifically, the lithium ions contained in the non-aqueous electrolyte accept electrons on the negative electrode collector due to charging and become lithium metal, which is deposited on the negative electrode collector. The lithium metal deposited on the negative electrode collector dissolves in the non-aqueous electrolyte in the form of lithium ions due to discharge. It should be noted that the lithium ions contained in the non-aqueous electrolyte may be derived from a lithium salt added to the non-aqueous electrolyte, may be lithium ions supplied by the positive electrode active material due to charging, or may be both.

[0076] A conductive sheet can be used as the negative electrode current collector. If the electrode assembly is a wound type, a strip-shaped conductive sheet is used. Examples of the conductive sheet include conductive films, metal foils, and the like.

[0077] The material of the negative electrode current collector (conductive sheet) can be a conductive material other than lithium metal and lithium alloy. The conductive material can be a metal. The conductive material is preferably a material that does not react with lithium. The conductive material preferably does not form any of alloys and intermetallic compounds with lithium. Examples of such conductive materials include copper (Cu), nickel (Ni), iron (Fe) and alloys containing these metal elements, or graphite preferentially exposed on the base surface. Examples of alloys include copper alloys, stainless steel (SUS), etc. From the perspective of having high conductivity, the conductive material is preferably copper and / or a copper alloy. The thickness of the negative electrode current collector is not particularly limited and can be in the range of 5 to 300 μm.

[0078] A negative electrode composite material layer may also be formed on the surface of the negative electrode current collector. For example, the negative electrode composite material layer may be formed by applying a paste containing a negative electrode active material, such as graphite, to at least a portion of the surface of the negative electrode current collector. To achieve a high-capacity lithium secondary battery exceeding that of a lithium-ion battery, the thickness of the negative electrode composite material layer is set to be sufficiently thin to allow lithium metal to precipitate at the negative electrode.

[0079] The negative electrode may also include a negative electrode current collector and sheet-like lithium metal or lithium alloy disposed on the negative electrode current collector. That is, a base layer (a layer of lithium metal or lithium alloy) containing lithium metal may also be pre-set on the negative electrode current collector. In addition to lithium, the lithium alloy may also contain elements such as aluminum, magnesium, indium, and zinc. By pre-setting the base layer and allowing lithium metal to precipitate thereon during charging, dendritic precipitation can be further effectively suppressed. The thickness of the base layer is not particularly limited, and for example, it may be in the range of 5 μm to 25 μm.

[0080] (positive electrode)

[0081] The positive electrode may include a positive electrode current collector and a positive electrode composite material layer supported by the positive electrode current collector. The positive electrode composite material layer includes a positive electrode active material. The positive electrode composite material layer may include a positive electrode active material, a conductive material, and a binder. The positive electrode composite material layer may be formed on only one side of the positive electrode current collector or on both sides. The positive electrode may be formed, for example, by applying a positive electrode composite material slurry including a positive electrode active material, a conductive material, and a binder onto the positive electrode current collector, drying the coating, and then rolling the coating.

[0082] The positive electrode active material is a material that absorbs and releases lithium ions. Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanions, fluorinated polyanions, and transition metal sulfides. Among these, lithium-containing transition metal oxides are preferred due to their low manufacturing cost and high average discharge voltage.

[0083] Examples of the transition metal element contained in the lithium-containing transition metal oxide include Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, and W. The lithium-containing transition metal oxide may contain one transition metal element or two or more. The transition metal element may be Co, Ni, and / or Mn. The lithium-containing transition metal oxide may contain one or more typical elements as needed. Typical elements include Mg, Al, Ca, Zn, Ga, Ge, Sn, Sb, Pb, and Bi. Typical elements may include Al, etc.

[0084] The conductive material is, for example, a carbon material, and examples of the carbon material include carbon black (acetylene black, Ketjen Black, etc.), carbon nanotubes, and graphite.

[0085] Examples of the binder include fluororesins, polyacrylonitrile, polyimide resins, acrylic resins, polyolefin resins, and rubber polymers. Examples of the fluororesins include polytetrafluoroethylene and polyvinylidene fluoride.

[0086] The positive electrode current collector may be a conductive sheet. A foil, a film, or the like may be used as the conductive sheet. A carbon material may be coated on the surface of the positive electrode current collector.

[0087] Examples of materials for the positive electrode current collector (conductive sheet) include metal materials such as Al, Ti, and Fe. The metal material may also be Al, an Al alloy, Ti, a Ti alloy, or an Fe alloy. The Fe alloy may also be stainless steel (SUS). The thickness of the positive electrode current collector is not particularly limited and may be in the range of 5 to 300 μm.

[0088] (non-aqueous electrolyte)

[0089] The non-aqueous electrolyte having lithium ion conductivity includes, for example, a non-aqueous solvent, and lithium ions and anions dissolved in the non-aqueous solvent. The non-aqueous electrolyte may be in a liquid state or a gel state.

[0090] The liquid non-aqueous electrolyte is prepared by dissolving a lithium salt in a non-aqueous solvent. The lithium salt dissolves in the non-aqueous solvent to generate lithium ions and anions.

[0091] The gel-like nonaqueous electrolyte comprises a lithium salt and a matrix polymer, or alternatively, a lithium salt, a nonaqueous solvent, and a matrix polymer. The matrix polymer is, for example, a polymer material that gels by absorbing the nonaqueous solvent. Examples of polymer materials include fluororesins, acrylic resins, and polyether resins.

[0092] As the lithium salt or anion, known anions used in non-aqueous electrolytes of lithium secondary batteries can be used. Specifically, BF4 - 、ClO4 - PF6 - CF3SO3 - CF3CO2 - , anions of imides, anions of oxalate complexes, etc. As anions of imides, N(SO2CF3)2 can be listed. - 、N(C m F 2m+1 SO2) x (C n F 2n+1 SO2) y - (m and n are each independently an integer of 0 or greater than 1, x and y are each independently 0, 1 or 2, and x + y = 2.) etc. The anion of the oxalate complex may also contain boron and / or phosphorus. Examples of the anion of the oxalate complex include bisoxalatoborate anion, BF2(C2O4) - PF4(C2O4) - PF2(C2O4)2 - The non-aqueous electrolyte may contain these anions alone or in combination of two or more.

[0093] From the perspective of suppressing the precipitation of lithium metal in the form of dendrites, the non-aqueous electrolyte preferably contains anions of an oxalate complex. Through the interaction between the anions of the oxalate complex and lithium, lithium metal is easily and uniformly precipitated in the form of fine particles. Therefore, it is easy to suppress the local precipitation of lithium metal. It is also possible to combine anions of the oxalate complex with other anions. Other anions can also be PF6 - and / or imide anions.

[0094] The non-aqueous electrolyte may also contain LiBF2(C2O4) (lithium difluorooxalatoborate) as a solute (lithium salt).

[0095] Examples of non-aqueous solvents include esters, ethers, nitriles, amides, or halogen-substituted products thereof. The non-aqueous electrolyte may contain any of these non-aqueous solvents alone or in combination. Examples of halogen-substituted products include fluorides and the like.

[0096] Examples of esters include carbonates and carboxylic acid esters. Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, and fluoroethylene carbonate (FEC). Examples of chain carbonates include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate. Examples of cyclic carboxylic acid esters include γ-butyrolactone and γ-valerolactone. Examples of chain carboxylic acid esters include ethyl acetate, methyl propionate, and methyl fluoropropionate.

[0097] Examples of ethers include cyclic ethers and chain ethers. Examples of cyclic ethers include 1,3-dioxolane, 4-methyl-1,3-dioxolane, tetrahydrofuran, and 2-methyltetrahydrofuran. Examples of chain ethers include 1,2-dimethoxyethane, diethyl ether, ethyl vinyl ether, methyl phenyl ether, benzyl ethyl ether, diphenyl ether, dibenzyl ether, 1,2-diethoxyethane, and diethylene glycol dimethyl ether.

[0098] The concentration of the lithium salt in the non-aqueous electrolyte is, for example, 0.5 mol / L or more and 3.5 mol / L or less. The concentration of the anion in the non-aqueous electrolyte may also be set to 0.5 mol / L or more and 3.5 mol / L or less. Alternatively, the concentration of the anion of the oxalate complex in the non-aqueous electrolyte may also be set to 0.05 mol / L or more and 1 mol / L or less.

[0099] The non-aqueous electrolyte may also contain additives. The additives may also form a coating on the negative electrode. By forming a coating derived from the additive on the negative electrode, the formation of dendrites is easily suppressed. Examples of such additives include vinylene carbonate, FEC, and vinyl ethyl carbonate (VEC).

[0100] (other)

[0101] The secondary battery (B) generally includes an outer case that houses an electrode group and a non-aqueous electrolyte. The outer case is not particularly limited, and a known outer case can be used.

[0102] Hereinafter, an example of the non-aqueous electrolyte secondary battery (B) of the present embodiment will be described in detail with reference to the accompanying drawings. The above-mentioned constituent elements can be used as constituent elements of the secondary battery of the example described below. In addition, the constituent elements of the example described below can be changed based on the above description. In addition, the matters described below can also be used for the above-mentioned embodiment. In addition, in the secondary battery described below, constituent elements that are not necessary in the secondary battery of the present disclosure can be omitted. It should be noted that in the following figures, the scales of the constituent elements have been changed for ease of understanding.

[0103] (Implementation Method 1)

[0104] In Embodiment 1, an example of a lithium secondary battery is described as an example of a nonaqueous electrolyte secondary battery (B). In this example, an example in which a spacer is formed on a separator is described. Figure 1 : is a longitudinal cross-sectional view schematically showing the non-aqueous electrolyte secondary battery 10 of the first embodiment. Figure 1 In the figure, illustration of the spacer and the space formed by the spacer is omitted.

[0105] Figure 1 The cylindrical secondary battery (non-aqueous electrolyte secondary battery) 10 shown includes a cylindrical battery case, and a wound electrode group 14 and a non-aqueous electrolyte (not shown) housed in the battery case. The battery case includes a case body 15, which is a cylindrical metal container with a bottom, and a sealing body 16 that seals the opening of the case body 15. A gasket 27 is arranged between the case body 15 and the sealing body 16. The airtightness of the battery case is ensured by the gasket 27. Insulating plates 17 and 18 are respectively arranged at both ends of the electrode group 14 in the winding axis direction in the case body 15.

[0106] The housing body 15 has a stepped portion 21 formed, for example, by partially punching out the side wall of the housing body 15 from the outside. The stepped portion 21 may also be formed in an annular shape along the circumference of the housing body 15. In this case, the sealing member 16 is supported by the surface of the stepped portion 21 on the opening side.

[0107] The sealing body 16 includes a partially opened metal plate 22, a lower valve body 23, an insulating member 24, an upper valve body 25 and a cover 26. In the sealing body 16, these components are stacked in this order. The above-mentioned components constituting the sealing body 16 are, for example, in the shape of a circular plate or a ring. The lower valve body 23 and the upper valve body 25 are connected to each other at their respective central portions, and an insulating member 24 is sandwiched between their respective peripheral portions. The partially opened metal plate 22 and the lower valve body 23 are connected to each other at their respective peripheral portions. The upper valve body 25 and the cover 26 are connected to each other at their respective peripheral portions. That is, the components except the insulating member 24 are electrically connected to each other.

[0108] A vent hole (not shown) is formed in the lower valve body 23. Therefore, when the internal pressure of the battery case rises due to abnormal heating, for example, the upper valve body 25 expands toward the lid 26 and separates from the lower valve body 23. This severs the electrical connection between the lower valve body 23 and the upper valve body 25. If the internal pressure rises further, the upper valve body 25 ruptures, allowing gas to escape through an opening (not shown) formed in the lid 26.

[0109] Figure 2 This is an enlarged view of a portion of the electrode group 14 . Figure 2 Including Figure 1 The portion near the positive electrode surrounded by region II and Figure 1 Region III surrounds the portion near the negative electrode. Figure 2 The height h of the spacer 53 is shown.

[0110] The electrode group 14 includes a positive electrode 11, a negative electrode 12, a separator 50, and a spacer 53. The positive electrode 11, the negative electrode 12, and the separator 50 are all in a strip shape. The separator 53 is formed on the separator 50. The positive electrode 11, the negative electrode 12, and the separator 50 are wound so that the separator 50 is disposed between the positive electrode 11 and the negative electrode 12, thereby forming the electrode group 14. The separator 50 and the spacer 53 formed on the separator 50 correspond to the separator (S) described above. In other words, the separator 50 corresponds to the base material of the separator (S).

[0111] The positive electrode 11 includes a positive electrode current collector 11 a and a positive electrode mixture layer 11 b. The positive electrode current collector 11 a is electrically connected to a lid 26 functioning as a positive electrode terminal via a positive electrode lead 19 . Figure 2 In FIG, a negative electrode 12 (negative electrode current collector) in a state where lithium metal is not deposited is shown. The negative electrode 12 is electrically connected to a case body 15 functioning as a negative electrode terminal via a negative electrode lead 20 .

[0112] Figure 2 In the example shown, the spacer 53 is formed on the main surface on the negative electrode 12 side of the two main surfaces of the separator 50, but it can also be formed on the main surface on the positive electrode 11 side. The spacer 53 forms a space 14s between the positive electrode 11 and the negative electrode 12.

[0113] In the secondary battery 10, lithium metal is deposited on the negative electrode 12 during charge. Since there is a space 14s between the positive electrode 11 and the negative electrode 12, the volume change of the electrode group 14 due to the deposition of lithium metal is reduced, and the cycle characteristics are improved.

[0114] Figure 3 An example of the planar shape of the spacer 53 is shown. Figure 3 The spacers 53 shown are formed of linear projections. Figure 3The linear protrusions shown are arranged in a grid pattern. More specifically, the linear protrusions are formed in a honeycomb pattern. The honeycomb pattern is a pattern formed by arranging a plurality of hexagons so that their sides are shared.

[0115] Figure 4 Another example of the planar shape of the spacer 53 is shown. Figure 4 The spacer 53 shown includes a plurality of linear protrusions separated from each other, with spaces P existing between the linear protrusions. Figure 5 Another example of the planar shape of the spacer 53 is shown. Figure 5 The spacer 53 includes a plurality of linear protrusions arranged in a stripe pattern. Figures 3 to 5 In the example shown, the region where no linear convex portion is formed constitutes Figure 2 The space shown is 14s.

[0116] (appendix)

[0117] The following technologies are disclosed through the description of the above embodiments.

[0118] (Technique 1)

[0119] A non-aqueous electrolyte secondary battery comprising:

[0120] positive electrode,

[0121] negative electrode,

[0122] a separator disposed between the positive electrode and the negative electrode,

[0123] non-aqueous electrolytes, and

[0124] a spacer disposed in at least one region selected from the group consisting of a region between the positive electrode and the separator and a region between the negative electrode and the separator,

[0125] The negative electrode is a negative electrode in which a metal serving as a negative electrode active material is deposited during charging and dissolved during discharging.

[0126] The aforementioned spacer contains resin and filler,

[0127] The resin contains a cellulose compound.

[0128] (Technique 2)

[0129] The non-aqueous electrolyte secondary battery according to aspect 1, wherein the content of the cellulose-based compound in the resin is 50% by volume or more.

[0130] (Technique 3)

[0131] The nonaqueous electrolyte secondary battery according to technology 1 or 2, wherein the resin is the cellulose-based compound.

[0132] (Technique 4)

[0133] The nonaqueous electrolyte secondary battery according to any one of techniques 1 to 3, wherein the cellulose-based compound includes at least one selected from the group consisting of methyl cellulose, ethyl cellulose, and carboxymethyl cellulose.

[0134] (Technique 5)

[0135] The nonaqueous electrolyte secondary battery according to any one of aspects 1 to 4, wherein the content of the resin in the spacer is 30% by volume or more.

[0136] (Technique 6)

[0137] The nonaqueous electrolyte secondary battery according to any one of techniques 1 to 5, wherein the spacer is formed on the separator.

[0138] (Technique 7)

[0139] The nonaqueous electrolyte secondary battery according to any one of techniques 1 to 6, wherein the spacer includes at least one selected from the group consisting of linear protrusions and dot-shaped protrusions.

[0140] (Technique 8)

[0141] A separator for a non-aqueous electrolyte secondary battery, comprising a substrate and a spacer formed on the substrate.

[0142] The aforementioned spacer contains resin and filler,

[0143] The resin contains a cellulose compound.

[0144] (Technique 9)

[0145] The separator according to technology 8, wherein the content of the cellulose-based compound in the resin is 50% by volume or more.

[0146] (Technique 10)

[0147] The separator according to technology 8 or 9, wherein the resin is the cellulose-based compound.

[0148] (Technology 11)

[0149] The separator according to any one of techniques 8 to 10, wherein the cellulose-based compound includes at least one selected from the group consisting of methyl cellulose, ethyl cellulose, and carboxymethyl cellulose.

[0150] (Technology 12)

[0151] The separator according to any one of techniques 8 to 11, wherein the content of the resin in the spacer is 30% by volume or more.

[0152] (Technology 13)

[0153] The separator according to any one of techniques 8 to 12, wherein the spacer includes at least one selected from the group consisting of linear protrusions and dot-shaped protrusions.

[0154] [Example]

[0155] Hereinafter, the secondary battery (B) of this embodiment will be specifically described based on examples. In the following examples, a plurality of lithium secondary batteries having different spacers were produced and evaluated.

[0156] (Battery A1)

[0157] A lithium secondary battery A1 was produced according to the following steps.

[0158] (1) Preparation of positive electrode

[0159] Prepare a rock salt-type lithium-containing transition metal oxide (NCA: positive electrode active material) containing Li, Ni, Co and Al (the molar ratio of Li relative to the total of Ni, Co and Al is 1.0) and having a layered structure. The lithium-containing transition metal oxide (NCA), acetylene black (AB: conductive material) and polyvinylidene fluoride (PVdF: binding material) are mixed in a mass ratio of NCA:AB:PVdF=95:2.5:2.5, and then an appropriate amount of N-methyl-2-pyrrolidone (NMP) is added and stirred to prepare a positive electrode composite material slurry. Then, the obtained positive electrode composite material slurry is applied to both sides of a strip of Al foil (positive electrode collector) and then dried. In this way, a stack comprising a positive electrode collector and a positive electrode composite material formed on the positive electrode collector is formed. Then, the stack is rolled using a roller. Finally, the rolled stack is cut into a specified size. In this manner, a positive electrode including a positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector was produced.

[0160] (2) Preparation of negative electrode

[0161] As the negative electrode, a negative electrode was used in which rolled lithium metal layers (25 μm thick) were provided on both surfaces of a strip-shaped copper foil (12 μm thick).

[0162] (3) Production of separators and spacers

[0163] First, a polyethylene tape-shaped porous membrane (average thickness 10 μm) was prepared as a substrate layer. Next, a porous composite material layer (average thickness 2 μm) was formed on one side of the substrate layer. The composite material layer was formed by sequentially forming a second layer and a first layer on the substrate layer.

[0164] The second layer is formed as follows. First, N-methyl-2-pyrrolidone (NMP) and calcium chloride are mixed in a mass ratio of 94.2:5.8. The mixture is heated to about 80°C to completely dissolve the calcium chloride. Next, the solution is returned to room temperature, 2200 g is collected, and 0.6 mol of paraphenylenediamine (PPD) is added to completely dissolve it. While maintaining the solution at about 20°C, 0.6 mol of terephthaloyl dichloride (TPC) is added in small amounts each time. The obtained solution is aged at about 20°C for 1 hour to prepare a polymerization solution. Next, 100 g of the polymerization solution is mixed with an N-methyl-2-pyrrolidone solution in which 5.8% by mass of calcium chloride is dissolved to obtain a solution (coating solution) having a concentration of 2% by mass of polyparaphenylene terephthalamide (PPTA) as an aromatic polyamide (aramid).

[0165] Next, the coating liquid was applied to the substrate layer using a slot die method to form a coating film. The substrate layer with the coating film was then left in an atmosphere at 25°C and 70% relative humidity for one hour to allow the aromatic polyamide to precipitate. The coating film was then washed with water to remove NMP and / or calcium chloride. The coating film was then dried at 60°C for five minutes to form the second layer.

[0166] The first layer is formed as shown below. First, particles of lithium phosphate (Li3PO4) and poly (N-vinyl acetamide) (PNVA) are mixed in a mass ratio of 100:8 to obtain a mixture. The lithium phosphate particles used are particles having a volume-based median particle size of 0.19 μm. By adding water (ion-exchanged water) to the obtained mixture and stirring it, a slurry (coating liquid) having a solid content concentration of 12% by mass is prepared. Then, the slurry is applied to the second layer by micro-gravure coating to form a coating film. Then, the coating film is dried in a drying oven in which a coating machine is also provided. In this way, the first layer is formed. In this way, a composite material layer is formed.

[0167] Next, a coating liquid containing ethyl cellulose and alumina particles (inorganic filler) was prepared. Ethyl cellulose and alumina particles were added to the coating liquid in a volume ratio of 40:60. N-methyl-2-pyrrolidone was used as the liquid medium (dispersion medium) of the coating liquid. Next, a dispenser was used to obtain Figure 3The coating liquid is applied to the composite material layer in the manner of the pattern (honeycomb shape) shown in FIG. Then, the coating liquid applied to the composite material layer is vacuum dried. In this way, a configuration is formed. Figure 3 spacers in the pattern shown.

[0168] (4) Preparation of non-aqueous electrolyte

[0169] Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a volume ratio of EC:DMC = 30:70. LiPF6 and LiBF2 (C2O4) were dissolved in the resulting mixed solvent to a concentration of 1 mol / L and 0.1 mol / L, respectively, to prepare a liquid non-aqueous electrolyte.

[0170] (5) Battery production

[0171] An aluminum tab was attached to the positive electrode obtained above. A nickel tab was attached to the negative electrode. In an inert gas atmosphere, the positive and negative electrodes were spirally wound with a separator interposed therebetween to produce a wound electrode assembly. The separator was positioned so that the separator was in contact with the negative electrode. This process produced Battery A1.

[0172] (Batteries A2~A3 and C1~C3)

[0173] Batteries A2 to A3 and C1 to C3 were produced under the same conditions and method as those for producing battery A1, except that the resin contained in the spacer was changed from ethyl cellulose to the resins shown in Table 1.

[0174] Each battery produced as described above was subjected to a charge and discharge test. In the charge and discharge test, the battery was charged in a thermostatic chamber at 45° C. under the following conditions, then rested for 20 minutes and discharged under the following conditions.

[0175] (Charge)

[0176] Constant current charging was performed at a current of 2.15 mA per unit area (cm2) of the electrode until the battery voltage reached 4.1 V, and then constant voltage charging was performed at a voltage of 4.1 V until the current value per unit area of ​​the electrode reached 0.54 mA.

[0177] (Discharge)

[0178] Constant current discharge was performed at a current of 2.15 mA per unit area of ​​the electrode until the battery voltage reached 3.75 V.

[0179] (Capacity maintenance rate)

[0180] In the charge-discharge test, the discharge capacity C(1) at the first cycle and the discharge capacity C(200) at the 200th cycle were measured. The capacity retention rate was then calculated using the following formula.

[0181] Capacity retention rate (%) = 100 × C (200) / C (1)

[0182] In addition, the initial efficiency was calculated for each battery produced. The initial efficiency is the ratio of the discharge capacity in the first cycle to the charge capacity in the first cycle. Table 1 shows a portion of the battery production conditions and evaluation results. Table 1 also shows the glass transition point (Tg) of the resin used in the spacer and the compressive strength of the resin alone.

[0183] [Table 1]

[0184]

[0185] Batteries A1 to A3 are secondary batteries (B) disclosed herein, and batteries C1 to C3 are batteries of comparative examples. The initial efficiency and capacity retention rate of batteries A1 to A3 are both high. That is, the initial characteristics and cycle characteristics of batteries A1 to A3 are high. The capacity retention rate of battery C1 is low. This is believed to be due to the low compressive strength of the resin. The initial efficiency of battery C2 is low. This is believed to be due to the reaction between the polyamic acid contained in the polyimide and lithium. The capacity retention rate of battery C3 is low. This is believed to be due to the low glass transition point and compressive strength of polyacrylic acid. On the other hand, the glass transition point Tg and compressive strength of the cellulose-based compound are high. In addition, unlike polyimide, the cellulose-based compound is considered to be less likely to produce unnecessary side reactions. Therefore, it is believed that the initial efficiency and cycle characteristics of batteries A1 to A3 are high.

[0186] Industrial applicability

[0187] The present disclosure can be used in non-aqueous electrolyte secondary batteries.

[0188] The present invention has been described with respect to presently preferred embodiments, but such disclosure is not to be construed as limiting. Various modifications and variations will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the appended claims should be construed as encompassing all modifications and variations that do not depart from the spirit and scope of the present invention.

[0189] Description of Reference Numerals

[0190] 10: Secondary battery (non-aqueous electrolyte secondary battery)

[0191] 11: Positive electrode

[0192] 12: Negative electrode

[0193] 14s: Space

[0194] 50: Separator

[0195] 53: Spacer

Claims

1. A non-aqueous electrolyte secondary battery comprising: positive electrode, negative electrode, a separator disposed between the positive electrode and the negative electrode, non-aqueous electrolytes, and a spacer disposed in at least one region selected from the group consisting of a region between the positive electrode and the separator and a region between the negative electrode and the separator, The negative electrode is a negative electrode in which a metal as a negative electrode active material is deposited during charging and the metal is dissolved during discharging. The spacer contains a resin and a filler, The resin contains a cellulose-based compound.

2. The nonaqueous electrolyte secondary battery according to claim 1, wherein The content of the cellulose compound in the resin is 50% by volume or more.

3. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein The resin is the cellulose-based compound.

4. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein The cellulose-based compound includes at least one selected from the group consisting of methyl cellulose, ethyl cellulose, and carboxymethyl cellulose.

5. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein The content of the resin in the spacer is 30% by volume or more.

6. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein The spacer is formed on the partition.

7. The nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein The spacer includes at least one selected from the group consisting of linear protrusions and dot-shaped protrusions.

8. A separator for a non-aqueous electrolyte secondary battery, comprising a substrate and a spacer formed on the substrate, The spacer contains a resin and a filler, The resin contains a cellulose-based compound.

9. The separator according to claim 8, wherein The content of the cellulose compound in the resin is 50% by volume or more.

10. The separator according to claim 8 or 9, wherein: The resin is the cellulose-based compound.

11. The separator according to claim 8 or 9, wherein: The cellulose-based compound includes at least one selected from the group consisting of methyl cellulose, ethyl cellulose, and carboxymethyl cellulose.

12. The separator according to claim 8 or 9, wherein The content of the resin in the spacer is 30% by volume or more.

13. The separator according to claim 8 or 9, wherein: The spacer includes at least one selected from the group consisting of linear protrusions and dot-shaped protrusions.

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