Non-aqueous electrolyte secondary battery

Abstract

This non-aqueous electrolyte secondary battery comprises a negative electrode including a negative electrode mixture, a separator, a positive electrode facing the negative electrode with the separator interposed therebetween, and a non-aqueous electrolyte. The negative electrode mixture includes a negative electrode active material. The negative electrode active material includes 3% by mass or more of a silicon-containing material. The silicon-containing material includes carbon composite particles. The carbon composite particle includes a carbon phase and a silicon phase dispersed within the carbon phase. The non-aqueous electrolyte contains a 5- or 6-membered cyclic compound component including a sulfur element as a ring-constituting element.

Description

[Technical Field] 【0001】 This disclosure relates to a non-aqueous electrolyte secondary battery. [Background technology] 【0002】 Non-aqueous electrolyte secondary batteries, such as lithium-ion secondary batteries, comprise a positive electrode, a negative electrode, and a non-aqueous electrolyte. Non-aqueous electrolyte solutions are primarily used. The negative electrode comprises a negative electrode mixture containing a negative electrode active material. The negative electrode active material is a material capable of electrochemically intercalating and releasing lithium ions. Examples of such materials include carbonaceous materials and silicon-containing materials. Furthermore, carbonaceous materials that do not intercalate or release lithium ions, such as carbon fibers and carbon nanotubes, may be added to the negative electrode mixture as conductive agents. 【0003】 Patent Document 1 proposes using a composite electrode material in a lithium-ion secondary battery, which includes particles containing an element capable of intercalating and releasing lithium ions, carbon particles capable of intercalating and releasing lithium ions, multi-walled carbon nanotubes, and carbon nanofibers. 【0004】 From the viewpoint of improving negative electrodes containing alloy-based active materials, Patent Document 2 proposes a negative electrode for a non-aqueous electrolyte secondary battery comprising a negative electrode current collector, a negative electrode active material layer containing an alloy-based active material that is supported on the surface of the negative electrode current collector and intercepts and releases lithium ions, and further comprising a resin layer on the surface of the negative electrode active material layer containing a lithium ion conductive resin component and an additive for non-aqueous electrolytes. [Prior art documents] [Patent Documents] 【0005】 [Patent Document 1] Japanese Patent Publication No. 2014-146519 [Patent Document 2] International Publication No. 2010 / 092815 [Overview of the project] 【Problems to be Solved by the Invention】 【0006】 Silicon-containing materials have a large volume change associated with the insertion and extraction of lithium ions. Among them, carbon composite particles containing a carbon phase and a silicon phase dispersed in the carbon phase have a large discharge capacity and a high utilization rate of the active material, so the volume change is particularly large. Therefore, every time charge and discharge are repeated, the carbon composite particles are likely to crack and a new surface appears. Side reactions with the electrolyte are likely to occur on the new surface, and when charge and discharge are repeated, the capacity decreases, so the capacity retention rate decreases and the cycle characteristics deteriorate. 【Means for Solving the Problems】 【0007】 One aspect of the present disclosure includes a negative electrode containing a negative electrode active material, a separator, a positive electrode facing the negative electrode through the separator, and a non-aqueous electrolyte, The negative electrode active material contains a negative electrode active material, The negative electrode active material contains a silicon-containing material of 3% by mass or more, The silicon-containing material contains carbon composite particles, The carbon composite particles contain a carbon phase and a silicon phase dispersed in the carbon phase, The non-aqueous electrolyte relates to a non-aqueous electrolyte secondary battery containing a 5-membered or 6-membered cyclic compound component containing sulfur element as a ring constituent element. 【Advantages of the Invention】 【0008】 In a non-aqueous electrolyte secondary battery using a negative electrode containing carbon composite particles containing a silicon phase, deterioration of cycle characteristics can be suppressed. 【Brief Description of the Drawings】 【0009】 [Figure 1] It is a perspective view of a part of a non-aqueous electrolyte secondary battery according to an embodiment of the present disclosure with a cutout. 【Modes for Carrying Out the Invention】 【0010】 Novel features of the present invention are described in the appended claims, but the present invention, both in terms of structure and content, and in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings. 【0011】 In non-aqueous electrolyte secondary batteries, carbonaceous materials such as graphite are generally used as the negative electrode active material. Theoretically, higher capacity can be obtained by using silicon-containing materials than by carbonaceous materials, but the volume change associated with the intercalation and release of lithium ions is large, and cracks easily occur in the active material particles, forming new surfaces. Side reactions with the non-aqueous electrolyte are likely to occur at these new surfaces, reducing capacity. Therefore, even when using silicon-containing materials, the capacity retention rate decreases when charging and discharging is repeated, making it difficult to ensure a sufficient lifespan. Among these, carbon composite particles containing a carbon phase and a silicon phase dispersed within the carbon phase are particularly ideal from the viewpoint of obtaining high capacity because they have a high active material utilization rate and can obtain a large discharge capacity. However, when charging and discharging is repeated, cracks easily occur not only in the silicon phase but also in the carbon phase that constitutes the matrix due to the volume change of the silicon phase. Therefore, when using carbon composite particles containing a silicon phase, more new surfaces are formed compared to when using carbonaceous materials that do not contain a silicon phase. Consequently, the capacity retention rate decreases when charging and discharging is repeated, and the cycle characteristics tend to deteriorate. 【0012】 In view of the above, (1) The non-aqueous electrolyte secondary battery of this disclosure includes a negative electrode containing a negative electrode mixture, a separator, a positive electrode facing the negative electrode via the separator, and a non-aqueous electrolyte. The negative electrode mixture includes a negative electrode active material. The negative electrode active material includes 3% by mass or more of silicon-containing material. The silicon-containing material includes carbon composite particles. The carbon composite particles include a carbon phase and a silicon phase dispersed within the carbon phase. The non-aqueous electrolyte includes a 5-membered or 6-membered cyclic compound component containing sulfur as a ring constituent element. Hereinafter, the 5-membered or 6-membered cyclic compound component containing sulfur as a ring constituent element may simply be referred to as the S-containing cyclic compound component. Furthermore, the silicon-containing material may be referred to as the Si-containing material, and the silicon phase as the Si phase. 【0013】 According to this disclosure, by using a non-aqueous electrolyte containing a sulfur-containing cyclic compound component, when the negative electrode contains a silicon-containing material including carbon composite particles containing a Si phase, the decrease in capacity retention rate can be suppressed even after repeated charging and discharging, and the deterioration of cycle characteristics can be suppressed. This is thought to be because, even if cracks occur in the silicon-containing material, including the carbon composite particles, and a new surface is generated during charging and discharging, a film is formed on the surface of the negative electrode active material by the sulfur-containing cyclic compound component, suppressing side reactions. From this, it is considered that the film formed on the surface of the silicon-containing material, including the new surface, due to the action of the sulfur-containing cyclic compound component is a low-resistance film that is less likely to inhibit the charging and discharging reaction. Furthermore, according to this disclosure, by using a silicon-containing material containing carbon composite particles as the negative electrode, a high initial discharge capacity can be secured. 【0014】 When a carbonaceous material without a Si phase is used as the negative electrode active material, the initial discharge capacity and the capacity retention rate after repeated charge-discharge cycles are almost the same even when a non-aqueous electrolyte containing S-containing cyclic compound components is used, compared to when the non-aqueous electrolyte does not contain S-containing cyclic compound components. In other words, the influence of S-containing cyclic compound components on the behavior of the cycle characteristics differs significantly between when a carbonaceous material without a Si phase is used as the negative electrode active material and when carbon composite particles containing a Si phase are used. 【0015】 (2) In the above (1), the silicon-containing material may further contain silicon oxide. 【0016】 (3) In (1) or (2) above, the silicon-containing material further comprises silicate composite particles, The silicate composite particles may include a silicate phase and a silicon phase dispersed within the silicate phase. 【0017】 (4) In any one of (1) to (3) above, the cyclic compound component may include a sulfur element as a constituent element of the ring, as well as a cyclic compound having a carbon-carbon unsaturated bond. 【0018】 (5) In any one of the above (1) to (4), the cyclic compound component may include 1,3-propensultone. 【0019】 (6) In any one of the above (1) to (5), the concentration of the cyclic compound component in the nonaqueous electrolyte may be 2% by mass or less. 【0020】 (7) In any one of the above (1) to (6), the negative electrode mixture may further contain carbon nanotubes. 【0021】 (8) In any one of the above (1) to (7), the nonaqueous electrolyte may further contain fluoroethylene carbonate. 【0022】 The non-aqueous electrolyte secondary battery of this disclosure will be described in more detail below, component by component, including items (1) to (8) above. To the extent that it is not technically inconsistent, at least one of items (1) to (8) above may be combined with at least one of the elements described below. 【0023】 (Negative electrode) The negative electrode includes a negative electrode mixture. The negative electrode may also include a negative electrode mixture and a negative electrode current collector that holds the negative electrode mixture. The negative electrode usually comprises a layered negative electrode mixture (hereinafter referred to as the negative electrode mixture layer). The negative electrode mixture includes at least a negative electrode active material. The negative electrode mixture may further include at least one selected from the group consisting of binders and thickeners. The negative electrode mixture may further include a conductive agent, etc. 【0024】 (Negative electrode mixture) (Negative electrode active material) The negative electrode active material includes at least a Si-containing material. The Si-containing material includes at least the carbon composite particles described above. The negative electrode may also include materials other than the Si-containing material as the negative electrode active material. 【0025】 (Si-containing material) Among Si-containing materials, carbon composite particles consist of a carbon phase and a Si phase dispersed within the carbon phase. Because the carbon phase is electrically conductive, even if cracks occur in the carbon composite particles due to the expansion and contraction of the Si phase, they are less likely to become isolated, and contact between the carbon composite particles and their surroundings is easily maintained. Therefore, the deterioration of cycle characteristics is easily suppressed. 【0026】 The carbon phase can consist of, for example, amorphous carbon (i.e., crystalline carbon) and crystalline carbon. Amorphous carbon may be hard carbon, soft carbon, or something else. Generally, amorphous carbon refers to a carbonaceous material in which the average interplanar spacing d002 of (002) planes, measured by X-ray diffraction, exceeds 0.340 nm. Examples of crystalline carbon include carbon with a graphite-type crystalline structure, such as graphite. Crystalline carbon, such as graphite, refers to a carbonaceous material in which d002 is 0.340 nm or less (for example, between 0.3354 nm and 0.340 nm). 【0027】 The Si phase content in the carbon composite particles is, for example, 30% to 80% by mass, and may also be 40% to 70% by mass. Within this range, a higher initial capacity can be obtained, and the deterioration of cycle characteristics can be easily reduced. In addition, by including a relatively large amount of carbon phase, even if cracks occur in the particles due to charging and discharging, the carbon phase can easily penetrate into the resulting voids, and the conductive path in the negative electrode mixture can be easily maintained. 【0028】 The content of carbon composite particles in the negative electrode active material is, for example, 3% by mass or more, and may be 4% by mass or more, or 5% by mass or more. When the content of carbon composite particles is in this range, the effects of side reactions on the newly formed surface are likely to appear due to volume changes associated with the intercalation and release of lithium ions. Therefore, the effect of using a non-aqueous electrolyte containing sulfur-containing cyclic compound components is likely to be particularly pronounced. From the viewpoint of ensuring higher cycle characteristics, the content of carbon composite particles in the negative electrode active material is, for example, 10% by mass or less. 【0029】 Carbon composite particles can be obtained, for example, by grinding a mixture of a carbon source and raw silicon while stirring in a ball mill or the like to produce fine particles, and then heat-treating the mixture in an inert atmosphere. Examples of carbon sources include petroleum resins such as coal pitch, petroleum pitch, and tar, as well as sugars and water-soluble resins such as carboxymethylcellulose (CMC), polyvinylpyrrolidone, cellulose, and sucrose. When mixing the carbon source and raw silicon, for example, the carbon source and raw silicon may be dispersed in a dispersion medium such as alcohol. After drying the milled mixture, the carbon phase is formed by heating it in an inert gas atmosphere, for example, at a temperature of 600°C or higher and 1000°C or lower, to carbonize the carbon source. 【0030】 Other Si-containing materials besides carbon composite particles include elemental silicon, silicon alloys, and silicon compounds. 【0031】 Si-containing materials may also contain composite particles other than carbon composite particles. Examples of such composite particles include composite particles in which a Si phase (fine Si phase) is dispersed within a lithium-ion conducting phase (matrix). When such composite particles are included in a Si-containing material, even higher capacity can be obtained, and the effect of suppressing the deterioration of cycle characteristics can be enhanced. 【0032】 The lithium ion conducting phase preferably includes at least one selected from the group consisting of an SiO2 phase and a silicate phase. The lithium ion conducting phase may further include a carbon phase. The lithium ion conducting phase may form an amorphous phase. However, it is not limited to this case; for example, at least a portion of each of the silicate phase and the carbon phase may be a crystalline phase including crystalline silicate or crystalline carbon, as described for carbon composite particles. Specific examples of composite particles include composite particles containing an SiO2 phase and a Si phase dispersed within the SiO2 phase, and composite particles containing a silicate phase and a Si phase dispersed within the silicate phase (silicate composite particles). However, composite particles are not limited to these specific examples. 【0033】 The SiO2 phase is an amorphous phase containing 95% by mass or more of silicon dioxide. Composite particles in which Si phases are dispersed in the SiO2 phase are represented by SiO x . x is, for example, 0.5 ≦ x < 2, and may be 0.8 ≦ x ≦ 1.6. SiO x can be obtained, for example, by heat-treating silicon monoxide and separating it into the SiO2 phase and fine Si phases by disproportionation reaction. When observing the cross-section of the SiO x particles using a transmission electron microscope (TEM: Transmission Electron Microscope), Si phases dispersed in the SiO2 phase can be confirmed. Such composite particles may be referred to as silicon oxides in this specification. When the negative electrode active material contains silicon oxides, it is easy to secure a higher initial discharge capacity. 【0034】 The silicate phase preferably contains at least one of an alkali metal element (Group 1 element other than hydrogen in the long-period periodic table) and a Group 2 element in the long-period periodic table. The alkali metal elements include lithium (Li), potassium (K), sodium (Na), etc. The Group 2 elements include magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), etc. The lithium silicate phase may have a composition represented by the formula: Li 2y SiO 2+y (0 < y < 2). y may be 1 / 2 or may be 1. Silicate composite particles in which Si phases are dispersed in the silicate phase can be obtained, for example, by pulverizing and micronizing a mixture of silicate and raw material silicon while stirring with a ball mill or the like, and then heat-treating the mixture in an inert atmosphere. 【0035】 The content of the Si phase dispersed in the silicate phase may be 30% by mass or more and 95% by mass or less, or may be 35% by mass or more and 75% by mass or less with respect to the whole of the silicate composite particles. 【0036】 The Si-containing material may consist solely of carbon composite particles, or it may consist of a combination of carbon composite particles and at least one other Si-containing material selected from other Si-containing materials. For example, the Si-containing material may include, in addition to carbon composite particles, at least one selected from the group consisting of silicon oxide and silicate composite particles. 【0037】 The silicon oxide content in the negative electrode active material is, for example, 0.1% by mass or more, may be 0.5% by mass or more, or may be 1% by mass or more. In this case, the initial discharge capacity can be further increased. The silicon oxide content in the negative electrode active material is, for example, 5% by mass or less. 【0038】 The silicate composite particle content in the negative electrode active material is, for example, 0.1% by mass or more, may be 0.5% by mass or more, or may be 1% by mass or more. In this case, a higher initial discharge capacity can be secured, and the decrease in capacity retention rate can be further suppressed. The silicate composite particle content in the negative electrode active material is, for example, 5% by mass or less. 【0039】 The composition of the Si-containing material can be determined, for example, by obtaining a backscattered electron image of the cross-section of the negative electrode mixture layer using a field emission scanning electron microscope (FE-SEM), observing the Si-containing material particles, and performing elemental analysis on the observed Si-containing material particles. For example, a battery can be disassembled, the negative electrode removed, washed with a non-aqueous solvent such as ethylene carbonate, dried, and then the cross-section of the negative electrode mixture layer processed with a cross-section polisher (CP) to obtain a sample. A backscattered electron image of the sample cross-section is taken using an FE-SEM. For elemental analysis, for example, electron probe microanalyzer (EPMA) analysis can be used. Qualitative and quantitative elemental analysis may also be performed using an Auger electron spectroscopy (AES) analyzer. The composition of the lithium-ion conducting phase can also be determined by the above analysis. The composition of the carbon phase can be confirmed based on d002, which is determined by X-ray diffraction. 【0040】 Si-containing materials are typically particulate materials. The average particle size (D50) of the Si-containing material is, for example, 1 μm to 25 μm, and may also be 4 μm to 15 μm. Good battery performance is easily obtained within this range. 【0041】 In this specification, the average particle size (D50) refers to the particle size at which the integrated volume value in the particle size distribution measured by laser diffraction scattering is 50% (volume-average particle size). For the measuring device, for example, the "LA-750" manufactured by HORIBA, Ltd. may be used. The average particle size of the Si-containing material may also be determined from a cross-sectional sample of the negative electrode formed to obtain a backscattered electron image using FE-SEM. The equivalent circle diameter of the cross-sections of 10 or more Si-containing material particles is determined, and their average value is determined as the average particle size. Here, the equivalent circle diameter refers to the diameter of a circle having the same area as the area of ​​the particle observed in the cross-section of the negative electrode. 【0042】 The Si phase dispersed within the carbon phase is typically composed of multiple crystallites. The crystallite size of the Si phase is, for example, 500 nm or less, and may also be 30 nm or less. There is no particular lower limit to the crystallite size of the Si phase, but it is, for example, 5 nm or more. The crystallite size is calculated from the full width at half maximum of the diffraction peaks attributed to the Si(111) plane in the X-ray diffraction (XRD) pattern of the Si phase using Scherrer's formula. 【0043】 The Si phase content in composite particles can be measured, for example, by Si-NMR. The following describes desirable measurement conditions for Si-NMR. 【0044】 Measurement device: Varian Solid State Nuclear Magnetic Resonance Spectrometer (INOVA-400) Probe: Varian 7mm CPMAS-2 MAS: 4.2kHz MAS speed: 4kHz Pulse: DD (45° pulse + 1H signal acquisition time decoupler) Repeat time: 1200 sec Observation width: 100kHz Observation center: around -100 ppm Signal acquisition time: 0.05 sec Total count: 560 Sample quantity: 207.6 mg 【0045】 From the viewpoint of improving conductivity, at least a portion of the particle surface of the Si-containing material may be coated with a conductive layer. The conductive layer contains a conductive material such as conductive carbon. The amount of the conductive layer is, for example, 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the total of the Si-containing material particles and the conductive layer. Si-containing material particles having a conductive layer on their surface can be obtained, for example, by mixing coal pitch or the like with the Si-containing material particles and heat-treating them in an inert atmosphere. 【0046】 The Si-containing material content in the negative electrode active material is 3% by mass or more, preferably 4% by mass or more, and may be 5% by mass or more. When the content is within this range, high initial capacity can be obtained, but the cycle characteristics tend to deteriorate. In this disclosure, even in such cases, high cycle characteristics can be ensured by using a non-aqueous electrolyte containing an S-containing cyclic compound component. The ratio of Si-containing material may be, for example, 15% by mass or less, and may be 10% by mass or less. These lower and upper limits can be arbitrarily combined. 【0047】 (Other negative electrode active materials) Other than Si-containing materials, examples of negative electrode active materials include at least one selected from the group consisting of carbonaceous materials without a Si phase, elemental Sn, Sn alloys, and Sn compounds (such as Sn oxides). Si-containing materials expand and contract in volume during charging and discharging, so if their proportion in the negative electrode active material is large, poor contact between the negative electrode active material and the negative electrode current collector is likely to occur during charging and discharging. Carbonaceous materials expand and contract less during charging and discharging than Si-containing materials. By using Si-containing materials and carbonaceous materials in combination, the contact state between negative electrode active material particles and between the negative electrode mixture and the negative electrode current collector can be maintained more effectively when charging and discharging is repeated. Therefore, by using Si-containing materials and carbonaceous materials without a Si phase in combination, it is easier to obtain excellent cycle characteristics while imparting a high capacity of the Si phase to the negative electrode. 【0048】 Examples of carbonaceous materials include graphite, easily graphitizable carbon (soft carbon), and difficult-to-graphitize carbon (hard carbon). Carbonaceous materials may be used individually or in combination of two or more types. 【0049】 Graphite is preferred as a carbonaceous material due to its excellent charge-discharge stability and low irreversible capacity. Examples of graphite include natural graphite, artificial graphite, and graphitized mesophase carbon particles. The graphite particles may partially contain amorphous carbon, easily graphitizable carbon, and difficult-to-graphitize carbon. 【0050】 Graphite is a carbonaceous material with a well-developed graphite-type crystal structure. The average interplanar spacing d002 of the (002) planes of graphite, measured by X-ray diffraction, may be, for example, 0.340 nm or less, or 0.3354 nm or more and 0.340 nm or less. The crystallite size Lc(002) of graphite may be, for example, 5 nm or more, or 5 nm or more and 200 nm or less. The crystallite size Lc(002) is measured, for example, by the Scherrer method. When the average interplanar spacing d002 and crystallite size Lc(002) of the (002) planes of graphite are within the above ranges, high capacitance is easily obtained. 【0051】 The total ratio of Si-containing material and carbonaceous material (carbonaceous material without Si phase) in the negative electrode active material is preferably 90% by mass or more, and may be 95% by mass or more or 98% by mass or more. The total ratio of Si-containing material and carbonaceous material in the negative electrode active material is 100% by mass or less. The negative electrode active material may be composed only of Si-containing material and carbonaceous material. 【0052】 (Binding agent) Examples of binders include resin materials. Examples of binders include fluororesins (e.g., polytetrafluoroethylene, polyvinylidene fluoride), polyolefin resins (e.g., polyethylene, polypropylene), polyamide resins (e.g., aramid resins), polyimide resins (e.g., polyimide, polyamideimide), acrylic resins (e.g., polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, ethylene-acrylic acid copolymer, or salts thereof), vinyl resins (e.g., polyvinyl acetate), and rubber-like materials (e.g., styrene-butadiene copolymer rubber (SBR)). A single binder may be used, or two or more may be used in combination. 【0053】 (Thickening agent) Examples of thickening agents include cellulose derivatives such as cellulose ether. Examples of cellulose derivatives include CMC and its modified forms, and methylcellulose. Modified forms of CMC also include salts of CMC. Examples of salts include alkali metal salts (e.g., sodium salts) and ammonium salts. A single thickening agent may be used alone, or two or more may be used in combination. 【0054】 (Conductive agent) Examples of conductive agents include conductive fibers and conductive particles. Examples of conductive fibers include carbon fibers and metal fibers. Carbon fibers also include carbon nanotubes (CNTs). Examples of conductive particles include conductive carbon (such as carbon black) and metal powders. Conductive agents may be used individually or in combination of two or more types. 【0055】 Si-containing materials exhibit significant volume changes due to expansion and contraction during charging and discharging. When the negative electrode mixture contains carbon nanotubes (CNTs), even if particle cracking occurs due to the expansion and contraction of the Si-containing material, the CNTs suppress the disruption of conductive paths, making it easier to obtain higher cycle characteristics. In particular, the effect of CNTs becomes pronounced when the Si-containing material content in the negative electrode active material is high (for example, 4% by mass or more). 【0056】 Carbon nanotubes (CNTs) are nano-sized carbonaceous materials with a structure in which sheets of six-membered ring networks (graphene) formed by carbon atoms are wound into a tubular shape. CNTs have excellent electrical conductivity. When the number of graphene layers constituting the tubular structure is one, it is called a single-walled carbon nanotube (SWCNT). When there are multiple layers, it is called a multi-walled carbon nanotube (MWCNT). It is called a nanotube. 【0057】 It is preferable that the CNTs include SWCNTs. In this case, it is easier to ensure higher cycle characteristics. 【0058】 The proportion of SWCNTs in total CNTs is, for example, 50% or more, may be 75% or more, or may be 90% or more. The proportion of SWCNTs in total CNTs is 100% or less. Note that the proportion of SWCNTs in total CNTs is the ratio of the number of SWCNTs to the total number of CNTs. 【0059】 The presence of carbon nanotubes (CNTs) in the negative electrode mixture can be confirmed, for example, by scanning electron microscope (SEM) images of a cross-section of the negative electrode mixture layer. 【0060】 The proportion of SWCNTs in the CNTs contained in the negative electrode mixture can be determined by the following method. A cross-sectional image of the negative electrode mixture layer or an image of CNTs is obtained using a scanning electron microscope (SEM). Multiple CNTs (e.g., 50 to 200) are arbitrarily selected from the SEM image for observation, the number of SWCNTs is determined, and the ratio of the number of SWCNTs to the total number of selected CNTs is calculated. 【0061】 Quantitative analysis of carbon nanotubes (CNTs) is performed, for example, by combining Raman spectroscopy and thermogravimetric analysis. 【0062】 From the viewpoint of reducing the disconnection of conductive paths during charging and discharging, the average diameter of the CNTs is, for example, 1 nm to 10 nm, or 1 nm to 5 nm. 【0063】 From the viewpoint of reducing the disconnection of conductive paths during charging and discharging, the average length of the CNTs is, for example, 1 μm to 100 μm, and may be 5 μm to 20 μm. 【0064】 The average length and average diameter of CNTs can be determined from images of the cross-section of the negative electrode mixture layer or the CNTs themselves, using at least one of SEM and TEM. More specifically, the average length and average diameter can be determined by arbitrarily selecting several CNTs (e.g., 50 to 200) from the captured image, measuring their length and diameter, and then averaging them. Note that the length of a CNT refers to the length when the CNT is stretched in a straight line. 【0065】 The CNT content in the negative electrode mixture is, for example, 0.005% by mass or more and 1% by mass or less, and may also be 0.01% by mass or more and 1% by mass or less, or 0.01% by mass or more and 0.05% by mass or less. When the CNT content in the negative electrode mixture is within this range, the effect of improving the conductivity of the negative electrode and improving the capacity retention rate in the initial stages of the charge-discharge cycle is greatly enhanced. 【0066】 (Negative electrode current collector) The negative electrode current collector is selected according to the type of non-aqueous electrolyte secondary battery. Examples of negative electrode current collectors include sheet-shaped current collectors. Metal foil may also be used as the current collector. Alternatively, a porous current collector may be used. Examples of porous current collectors include mesh materials, perforated sheets, and expanded metal. 【0067】 Examples of materials for the negative electrode current collector include stainless steel, nickel, nickel alloys, copper, and copper alloys. 【0068】 The thickness of the negative electrode current collector is not particularly limited and may be, for example, 1 μm or more and 50 μm or less, or 5 μm or more and 30 μm or less. 【0069】 (others) The negative electrode can be formed, for example, by coating the surface of a negative electrode current collector with a negative electrode slurry, which is obtained by dispersing the components of a negative electrode mixture in a dispersion medium, and then drying it. The dried coating may be rolled if necessary. 【0070】 The dispersion medium is not particularly limited and includes, for example, water, alcohol (e.g., ethanol), ether (e.g., tetrahydrofuran), amide (e.g., dimethylformamide), N-methyl-2-pyrrolidone (NMP), or a mixture thereof. 【0071】 (positive electrode) The positive electrode may include a positive electrode current collector and a positive electrode mixture layer retained on the surface of the positive electrode current collector. The positive electrode mixture layer can be formed by applying a positive electrode slurry in which a positive electrode mixture is dispersed in a dispersion medium onto the surface of the positive electrode current collector and drying it. The dried coating film may be rolled if necessary. The positive electrode mixture contains, as essential components, a positive electrode active material, and may contain, as optional components, a binder, a conductive agent, etc. The dispersion medium can be selected, for example, from the dispersion media exemplified for the negative electrode. 【0072】 As the positive electrode active material, for example, a composite oxide containing lithium and a transition metal is used. Examples of the transition metal include Ni, Co, Mn, etc. Examples of the composite oxide containing lithium and a transition metal include, for example, Li a CoO2, Li a NiO2, Li a MnO2, Li a Co b1 Ni 1-b1 O2, Li a Co b1 M 1-b1 O c1 , Li a Ni 1-b1 M b1 O c1 , Li a Mn2O4, Li a Mn 2-b1 M b1 O4. Here, a = 0 to 1.2, b1 = 0 to 0.9, c1 = 2.0 to 2.3. M is at least one selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B. The a value indicating the molar ratio of lithium increases or decreases by charge and discharge. 【0073】 Among them, Li a Ni b2 M 1-b2 O2 (0 < a ≤ 1.2, 0.3 ≤ b2 ≤ 1, and M is at least one selected from the group consisting of Mn, Co, and Al.) represented by lithium nickel composite oxide is preferred. From the viewpoint of increasing the capacity, it is more preferable to satisfy 0.8 ≤ b2 ≤ 1 or 0.85 ≤ b2 ≤ 1. From the viewpoint of the stability of the crystal structure, Lia Ni b2 Co c2 Al d O2 (0 < a ≤ 1.2, 0.8 ≤ b2 < 1, 0 < c2 < 0.2 (or 0 < c2 ≤ 0.18), 0 < d ≤ 0.1, b2 + c2 + d = 1) is more preferable. 【0074】 As the binder, resin materials exemplified for the negative electrode can be used. As the conductive agent, for example, it can be selected from the conductive agents exemplified for the negative electrode. Graphite may be used as the conductive agent. 【0075】 The shape and thickness of the positive electrode current collector can be selected from the shapes and ranges described for the negative electrode current collector, respectively. Examples of the material of the positive electrode current collector include stainless steel, aluminum, aluminum alloy, and titanium. 【0076】 (Separator) Generally, it is desirable to interpose a separator between the positive electrode and the negative electrode. The separator has high ion permeability and appropriate mechanical strength and insulation. Examples of the separator include microporous thin films, woven fabrics, and non-woven fabrics. The separator may have a single-layer structure or a multi-layer structure. The multi-layer structure separator may be a laminate containing at least two selected from the group consisting of microporous thin films, woven fabrics, and non-woven fabrics as layers. As the material of the separator, polyolefin (for example, polypropylene, polyethylene) is preferable. 【0077】 (Non-aqueous electrolyte) The non-aqueous electrolyte is usually used in a liquid state, but may be in a state where its fluidity is restricted by a gelling agent or the like. The non-aqueous electrolyte usually contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent, and in addition to these, it contains an additive. In the present disclosure, the non-aqueous electrolyte contains an S-containing cyclic compound component. The non-aqueous electrolyte may further contain an additive other than the S-containing cyclic compound component. 【0078】 (Non-aqueous solvent) Examples of non-aqueous solvents include cyclic carbonate esters, linear carbonate esters, cyclic carboxylic acid esters, and linear carboxylic acid esters. Examples of cyclic carbonate esters include propylene carbonate (PC), ethylene carbonate (EC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), etc. Examples of linear carbonate esters include diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), etc. Examples of cyclic carboxylic acid esters include γ-butyrolactone (GBL), γ-valerolactone (GVL), etc. Examples of linear carboxylic acid esters include methyl formate, ethyl formate, propyl formate, methyl acetate (MA), ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate. The non-aqueous electrolyte may contain one non-aqueous solvent or a combination of two or more non-aqueous solvents. 【0079】 (Lithium salt) Examples of lithium salts include LiClO4, LiBF4, LiPF6, LiAlCl4, LiSbF6, LiSCN, LiCF3SO3, LiCF3CO2, LiAsF6, LiB 10 Cl 10Examples include lithium lower aliphatic carboxylates, LiCl, LiBr, LiI, phosphates, borates, and imide salts. Examples of phosphates include lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFBOP), and lithium tetrafluoro(oxalato)phosphate. Examples of borates include lithium bis(oxalato)borate (LiBOB) and lithium difluoro(oxalato)borate (LiDFOB). Examples of imide salts include lithium bisfluorosulfonylimide (LiN(FSO2)2), lithium bistrifluoromethanesulfonate (LiN(CF3SO2)2), lithium trifluoromethanesulfonate nonafluorobutanesulfonate (LiN(CF3SO2)(C4F9SO2)), and lithium bispentafluoroethanesulfonate (LiN(C2F5SO2)2). The non-aqueous electrolyte may contain one lithium salt or a combination of two or more lithium salts. 【0080】 The concentration of lithium salt in the electrolyte is, for example, between 0.5 mol / L and 2 mol / L. 【0081】 (S-containing cyclic compound component) S-containing cyclic compound components are cyclic compound components that contain the element S as a constituent element of the ring. The cyclic compound included in the S-containing cyclic compound component may contain the element oxygen in addition to the element S that constitutes the ring. For example, the S-containing cyclic compound may contain an oxygen atom as a constituent element of the ring, or it may contain an oxo group (=O) bonded to the ring as a substituent, or it may contain both. The oxo group may be bonded to the carbon element that constitutes the ring, but it is preferable that it is bonded to the S element that constitutes the ring. 【0082】 Such sulfur-containing cyclic compounds may be, for example, at least one selected from the group consisting of sulfuric acid esters, sulfite esters, and sulfonic acid esters. Sulfuric acid esters have an -OS(=O)2-O- structure. Sulfite esters have an -OS(=O)-O- structure. Sulfonic acid esters have an -S(=O)2-O- structure. Cyclic compounds also include salts of these esters. Among these, cyclic sulfite esters and cyclic sulfonic acid esters are preferred. 【0083】 Examples of cyclic sulfate esters include alkylene sulfate and alkenylene sulfate. Specific examples of cyclic sulfate esters include ethylene sulfate, propylene sulfate, trimethylene sulfate, butylene sulfate, and vinylene sulfate. Examples of cyclic sulfite esters include at least one selected from the group consisting of alkylene sulfite and alkenylene sulfite. Specific examples of cyclic sulfite esters include ethylene sulfite, propylene sulfite, trimethylene sulfite, butylene sulfite, and vinylene sulfite. Examples of cyclic sulfonic acid esters include at least one selected from the group consisting of alkanesultone and alkenesultone. Specific examples of cyclic sulfonic acid esters include 1,3-propanesultone, 1,4-butanesultone, and 1,3-propensultone. 【0084】 The sulfur-containing cyclic compound may have one or more hydrogen atoms of the compounds exemplified above substituted with substituents. Examples of substituents include alkyl groups, alkenyl groups, hydroxyalkyl groups, hydroxyl groups, alkoxy groups, and halogen atoms. The number of carbon atoms of the substituent may be 1 to 4 or 1 to 3. Examples of halogen atoms include chlorine atoms and fluorine atoms. 【0085】 The sulfur-containing ring in sulfur-containing cyclic compounds is usually 5-membered or 6-membered. 【0086】 The S-containing cyclic compound component may contain one of these S-containing cyclic compounds, or a combination of two or more. Preferably, the S-containing cyclic compound component contains an S-containing cyclic compound having a carbon-carbon unsaturated bond. The carbon-carbon unsaturated bond may constitute part of the S-containing ring, or it may be a substituent of the S-containing ring. Such substituents include alkenyl groups such as vinyl groups and allyl groups (C 2-4 Examples include alkenyl groups. Specific examples of such sulfur-containing cyclic compounds include 1,3-propensultone, vinylene sulfite, vinylethylene sulfite, and vinylene sulfate. When the sulfur-containing cyclic compound component contains at least 1,3-propensultone, a film with excellent film quality is easily formed on the surface of the negative electrode active material particles, including the newly formed surface, resulting in higher cycle characteristics. The sulfur-containing cyclic compound component may also contain 1,3-propensultone and other sulfur-containing cyclic compounds. 【0087】 In a non-aqueous electrolyte secondary battery, the concentration of the sulfur-containing cyclic compound component in the non-aqueous electrolyte may be, for example, 2% by mass or less, or 1% by mass or less. This concentration of the sulfur-containing cyclic compound component is a value determined for the non-aqueous electrolyte sampled from an initial non-aqueous electrolyte secondary battery. In a non-aqueous electrolyte secondary battery, the sulfur-containing cyclic compound component is used for film formation, so the concentration of the sulfur-containing cyclic compound component in the non-aqueous electrolyte changes during storage or during charge-discharge cycles. Therefore, it is sufficient that the sulfur-containing cyclic compound component remains in the non-aqueous electrolyte sampled from an initial non-aqueous electrolyte secondary battery at a concentration above the detection limit. The content of the sulfur-containing cyclic compound component in the electrolyte may be 0.01% by mass or more, 0.1% by mass or more, 0.25% by mass or more, or 0.5% by mass or more. The concentration of 1,3-propensultone may be within the above range. 【0088】 An initial non-aqueous electrolyte secondary battery is, for example, a non-aqueous electrolyte secondary battery that has been assembled and subjected to a break-in charge-discharge cycle (and aging as necessary). A commercially available non-aqueous electrolyte secondary battery may also be used as an initial non-aqueous electrolyte secondary battery, and the non-aqueous electrolyte may be collected and subjected to analysis. 【0089】 The concentration of the sulfur-containing cyclic compound component in the non-aqueous electrolyte used in the manufacture of non-aqueous electrolyte secondary batteries may be 0.1% by mass or more, 0.2% by mass or more, or 0.25% by mass or more, or 0.5% by mass or more. The content of the sulfur-containing cyclic compound component in the electrolyte used in the manufacture of non-aqueous electrolyte secondary batteries is, for example, 2% by mass or less. The concentration of 1,3-propensultone may be within the above range. 【0090】 (others) Non-aqueous electrolytes may contain additives other than sulfur-containing cyclic compound components. Examples of such additives include sulfur-containing compounds other than the sulfur-containing cyclic compound components mentioned above, phosphorus-containing compounds, nitrogen-containing compounds, vinyl ethylene carbonate, FEC, and aromatic compounds (cyclohexylbenzene, fluorobenzene, etc.). Sulfur-containing compounds (sulfur-containing compounds) include at least one selected from the group consisting of linear sulfuric acid esters (ethyl sulfuric acid, methyl sulfuric acid, etc.), linear sulfite esters, and linear sulfonic acid esters. Sulfur-containing compounds also include salts of these esters (ethyl sulfate, methyl sulfate, etc.). Non-aqueous electrolytes may contain one of these additives or a combination of two or more. 【0091】 Non-aqueous electrolyte secondary batteries preferably contain FEC. In this case, higher cycle characteristics are more easily obtained. FEC may be included in small amounts as an additive (e.g., 0.1% to 2% by mass) or in relatively large amounts as a non-aqueous solvent in the non-aqueous electrolyte (e.g., more than 2% by mass). 【0092】 (others) One example of the structure of a non-aqueous electrolyte secondary battery is a structure in which an electrode group, in which the positive and negative electrodes are wound with a separator in between, is housed together with the non-aqueous electrolyte in an outer casing. However, the structure of a non-aqueous electrolyte secondary battery is not limited to this structure. For example, the electrode group may be a stacked type in which the positive and negative electrodes are stacked with a separator in between. The form of the non-aqueous electrolyte secondary battery is also not limited, and may be cylindrical, prismatic, coin-type, button-type, or laminate-type, for example. 【0093】 Figure 1 is a schematic perspective view showing a portion of a rectangular non-aqueous electrolyte secondary battery according to one embodiment of the present disclosure. The non-aqueous electrolyte secondary battery comprises a bottomed rectangular battery case 4, an electrode group 1 and an electrolyte (not shown) housed within the battery case 4. The electrode group 1 has a long strip-shaped negative electrode, a long strip-shaped positive electrode, and a separator interposed between them. The negative electrode current collector of the negative electrode is electrically connected to a negative electrode terminal 6 provided on a sealing plate 5 via a negative electrode lead 3. The negative electrode terminal 6 is insulated from the sealing plate 5 by a resin gasket 7. The positive electrode current collector of the positive electrode is electrically connected to the back surface of the sealing plate 5 via a positive electrode lead 2. That is, the positive electrode is electrically connected to the battery case 4, which also serves as the positive electrode terminal. The periphery of the sealing plate 5 fits into the open end of the battery case 4, and the fitting portion is laser welded. The sealing plate 5 has an electrolyte injection hole, which is sealed by a seal 8 after the electrolyte is injected. 【0094】 [Examples] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to the following examples. 【0095】 Examples 1-3 and Comparative Examples 1-8 A non-aqueous electrolyte secondary battery was fabricated and evaluated using the following procedure. (1) Fabrication of the negative electrode An appropriate amount of water was added to the negative electrode mixture and mixed to obtain a negative electrode slurry. The negative electrode mixture used was a mixture of negative electrode active material, binder, and conductive agent. 【0096】 The negative electrode active materials used were those listed in Table 1, with their respective content percentages in the total negative electrode active material being the values ​​shown in Table 1. However, the content percentages for each negative electrode active material were calculated excluding the conductive layer. The negative electrode active materials shown in Table 1 are as follows: (a) Carbon composite particles: Containing a carbon phase and a Si phase dispersed within the carbon phase, the surface is coated with a conductive layer containing conductive carbon, resulting in carbon composite particles (Si phase content in particles excluding the conductive layer is 50% by mass, average particle size (D50) 6 μm) (b) Silicon oxide: SiO2 on the surface coated with a conductive layer containing conductive carbon. x Particles (x=1, average particle size (D50) 5μm) (c) Silicate composite particles: Li whose surface is coated with a conductive layer containing conductive carbon. 2y SiO 2+y Particles (y=0.5, average particle diameter (D50) 10μm) (d) Graphite particles: Average particle size (D50) 25 μm 【0097】 The binders used were sodium polyacrylate (PAA-Na), sodium salt of CMC (CMC-Na), and SBR. The conductive agent used was carbon nanotubes (CNTs) containing 90% or more SWCNTs (average diameter approximately 1.6 nm, average length approximately 5 μm). 【0098】 The CNT content in the negative electrode mixture (dry solids) was set to 0.05% by mass. The PAA-Na, CMC-Na, and SBR content in the negative electrode mixture was set to 1% by mass, based on dry solids. 【0099】 Next, the negative electrode slurry is applied to the surface of the copper foil, the coating is dried, and then it is rolled to form a negative electrode mixture layer (80 μm thick, 1.6 g / cm³ density) on both sides of the copper foil. 3 ) was formed, and the negative electrode was obtained. 【0100】 (2) Preparation of the positive electrode Lithium-containing composite oxide (LiNi 0.8 Co 0.18 Al 0.0295 parts by mass of O2 were mixed with 2.5 parts by mass of acetylene black, 2.5 parts by mass of polyvinylidene fluoride, and an appropriate amount of NMP to obtain a positive electrode slurry. Next, the positive electrode slurry was applied to the surface of an aluminum foil, the coating was dried, and then the foil was rolled to form a positive electrode mixture layer (thickness 95 μm, density 3.6 g / cm³) on both sides of the aluminum foil. 3 A positive electrode was obtained by forming a positive electrode. 【0101】 (3) Preparation of non-aqueous electrolytes A non-aqueous electrolyte was prepared by dissolving LiPF6 and, optionally, 1,3-propensultone (PRES) in a mixed solvent of EC, DMC, and MA (EC:DMC:MA = 20:60:20 (volume ratio)), and then mixing in FEC. The concentration of LiPF6 in the non-aqueous electrolyte was 1.35 mol / L. The concentration of PRES in the non-aqueous electrolyte (concentration at the time of non-aqueous electrolyte preparation) was the value shown in Table 1 (mass%). The concentration of FEC in the non-aqueous electrolyte was 1 mass%. 【0102】 (4) Fabrication of non-aqueous electrolyte secondary batteries An aluminum positive electrode lead was attached to the positive electrode obtained above, and a nickel negative electrode lead was attached to the negative electrode obtained above. In an inert gas atmosphere, the positive and negative electrodes were wound in a spiral shape via a polyethylene thin film (separator) to create a wound electrode group. The electrode group was housed in a bag-shaped outer casing made of a laminate sheet with an aluminum layer, a predetermined amount of the electrolyte was injected, and the outer casing was sealed to create a non-aqueous electrolyte secondary battery. When housing the electrode group in the outer casing, parts of the positive and negative electrode leads were exposed to the outside of the outer casing. 【0103】 "evaluation" The following evaluations were performed using the obtained non-aqueous electrolyte secondary battery. (1)Initial capacity Under 45°C conditions, a non-aqueous electrolyte secondary battery was charged with a constant current of 0.5C (180mA) until its voltage reached 4.2V, and then charged with a constant voltage of 4.2V until the current reached 0.05C (18mA). After a 10-minute pause, the non-aqueous electrolyte secondary battery was discharged with a constant current of 0.7C (252mA) until its voltage reached 2.5V. The discharge capacity (Ci) at this time was determined as the initial capacity. 【0104】 (2) Cycle characteristics To determine the discharge capacity Ci, the charge, pause, and discharge cycle was defined as one cycle, and this cycle was repeated 100 times. The discharge capacity (Cc) at the 100th cycle was then determined. The ratio (%) of the discharge capacity Cc to the initial discharge capacity Ci (set as 100%) was calculated as the capacity retention rate and used as an indicator of cycle characteristics. 【0105】 The results for the examples and comparative examples are shown in Table 1. In Table 1, E1 to E3 represent Examples 1 to 3, and C1 to C8 represent Comparative Examples 1 to 8. The initial volume is expressed as the ratio (%) of the initial volume Ci of each example, with the initial volume Ci of Comparative Example 1 set to 100%. 【0106】 [Table 1] 【0107】 As shown in Table 1, when using carbon composite particles in which the Si phase is dispersed within the carbon phase, the initial capacity is higher, but the cycle characteristics are reduced compared to when using a carbonaceous material without the Si phase as the anode active material (comparison of C1 with C3 and C4). When the anode active material contains silicon oxide in addition to carbon composite particles, the reduction in cycle characteristics becomes larger (comparison of C3 with C4). 【0108】 On the other hand, when using only carbonaceous materials that do not contain a Si phase as the negative electrode active material, the initial capacity and cycle characteristics are almost the same as when using a non-aqueous electrolyte that does not contain a S-containing cyclic compound component, even when using a non-aqueous electrolyte that does not contain a S-containing cyclic compound component (compared to C1 and C2). 【0109】 In contrast, when carbon composite particles are used, and a non-aqueous electrolyte containing sulfur-containing cyclic compound components is used, the deterioration of cycle characteristics is suppressed while maintaining a high initial capacity, resulting in excellent cycle characteristics (E1-E3). This is thought to be because the sulfur-containing cyclic compound components form a low-resistance film on the surface of the silicon-containing material particles, including the carbon composite particles, allowing for effective utilization of the high capacity of the negative electrode active material, and preventing the inhibition of charging and discharging, thus suppressing the decrease in capacity even after repeated charging and discharging. 【0110】 When silicon oxide or silicate composite particles are used as the negative electrode active material instead of carbon composite particles, a relatively high initial capacity can be obtained, but the cycle characteristics are significantly lower compared to C1 (comparison of C1 with C6 and C8). When such negative electrode active materials are used, combining them with a non-aqueous electrolyte containing sulfur-containing cyclic compound components improves the cycle characteristics to some extent, but it is still about the same as C1. These results indicate that a particularly excellent improvement in cycle characteristics can be obtained when a non-aqueous electrolyte containing sulfur-containing cyclic compound components is combined with a negative electrode active material containing carbon composite particles. 【0111】 Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention. [Industrial applicability] 【0112】 The non-aqueous electrolyte secondary battery described herein is useful as a main power source for mobile communication devices, portable electronic devices, and the like. However, these are merely examples, and the applications of the non-aqueous electrolyte secondary battery are not limited to these. [Explanation of symbols] 【0113】 1: Electrode group 2: Positive lead 3: Negative lead 4: Battery case 5: Sealing board 6: Negative terminal 7: Gasket 8: Sealing

Claims

[Claim 1] The material comprises a negative electrode containing a negative electrode mixture, a separator, a positive electrode facing the negative electrode via the separator, and a non-aqueous electrolyte. The aforementioned negative electrode mixture contains a negative electrode active material, The negative electrode active material comprises 3% by mass or more and 10% by mass or less of silicon-containing material. The silicon-containing material includes carbon composite particles, The carbon composite particles comprise a carbon phase and a silicon phase dispersed within the carbon phase. The content of the silicon phase in the carbon composite particles is 40% by mass or more. The non-aqueous electrolyte is liquid and comprises a five- or six-membered cyclic compound component containing sulfur as a ring element and fluoroethylene carbonate. The aforementioned cyclic compound component includes 1,3-propensultone, A non-aqueous electrolyte secondary battery in which the concentration of the cyclic compound component in the non-aqueous electrolyte is 2% by mass or less. [Claim 2] A negative electrode comprising a negative electrode mixture, a separator, a positive electrode facing the negative electrode via the separator, and a non-aqueous electrolyte, The aforementioned negative electrode mixture contains a negative electrode active material, The negative electrode active material contains 3% by mass or more of silicon-containing material. The silicon-containing material includes carbon composite particles, The carbon composite particles comprise a carbon phase and a silicon phase dispersed within the carbon phase. The content of the silicon phase in the carbon composite particles is 40% by mass or more. The non-aqueous electrolyte is liquid and comprises a five- or six-membered cyclic compound component containing sulfur as a ring element and fluoroethylene carbonate. The aforementioned cyclic compound component includes 1,3-propensultone, The concentration of the cyclic compound component in the non-aqueous electrolyte is 2% by mass or less. A non-aqueous electrolyte secondary battery, wherein the concentration of the fluoroethylene carbonate in the non-aqueous electrolyte is 0.1% by mass or more and 2% by mass or less. [Claim 3] The silicon-containing material further comprises at least one selected from the group consisting of silicon oxide particles and silicate composite particles, The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the silicate composite particles comprise a silicate phase and a silicon phase dispersed within the silicate phase. [Claim 4] The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the negative electrode mixture further comprises carbon nanotubes. [Claim 5] The positive electrode includes a positive electrode active material, The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the positive electrode active material comprises a lithium nickel composite oxide represented as Li a Ni b2 M 1-b2 O 2 (where 0 < a ≤ 1.2, 0.3 ≤ b2 ≤ 1, and M is at least one selected from the group consisting of Mn, Co, and Al). [Claim 6] The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the content of the carbon composite particles in the negative electrode active material is 3% by mass or more and 10% by mass or less. [Claim 7] The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the negative electrode active material comprises a carbonaceous material that does not contain a silicon phase.

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