JP2015170477A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery having a positive electrode of which the operating potential is 4.3 V or higher based on metallic lithium, and having superior input and output characteristics and high durability.SOLUTION: In a nonaqueous electrolyte secondary battery, the upper-limit operating potential of a positive electrode is 4.3 V or higher based on metallic lithium. The positive electrode includes a positive electrode active material, and a carbon-deposited phosphate compound. The carbon-deposited phosphate compound is arranged by depositing a conducting carbon on at least part of the surface of an ion-conducting inorganic phosphate compound. According to a preferred embodiment, the inorganic phosphate compound includes a phosphate of an alkali metal element and/or Group II element (typically, an alkali-earth metal element).

Description

  The present invention relates to a non-aqueous electrolyte secondary battery. More specifically, the present invention relates to the battery in which the operating upper limit potential of the positive electrode is set to 4.3 V or more based on metallic lithium.

Nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries are preferably used for so-called portable power supplies, high-output power supplies for vehicles, and the like because they are lighter and have higher energy density than existing batteries.
In such a non-aqueous electrolyte secondary battery, higher energy density has been studied as part of performance improvement. Such an increase in energy density can be realized by setting the positive electrode operating potential higher than in the prior art, for example. However, when the upper limit operating potential of the positive electrode is set to about 4.3 V or more on the basis of metallic lithium, battery characteristics (typically durability, for example, high temperature cycle characteristics) may be deteriorated due to the positive electrode having a high potential. is there.
As a technology related to this, Patent Document 1 discloses that the surface of the active material particles is coated with lithium ion conductive glass, thereby suppressing the decomposition reaction of the non-aqueous electrolyte in a high potential state and improving the self-discharge characteristics. In addition, it is disclosed that battery swelling during standing at high temperatures can be reduced.

JP 2003-173770 A

However, lithium ion conductive glass generally has very low electronic conductivity. For this reason, when the surface of the active material particles is covered with lithium ion conductive glass as in Patent Document 1, the electron conductivity in the active material layer may be inhibited and the resistance may increase. Such an increase in resistance becomes a problem especially in a battery (for example, a battery used as a power source of a vehicle) used in a mode in which high-rate charging / discharging is repeated, and may cause a decrease in input / output characteristics.
The present invention has been made in view of such a point, and an object of the present invention is a non-aqueous electrolyte secondary battery having a high energy density in which the operating upper limit potential of the positive electrode is set to 4.3 V or higher with respect to metallic lithium. Thus, a non-aqueous electrolyte secondary battery having both excellent input / output characteristics and high durability is provided.

The non-aqueous electrolyte secondary battery disclosed herein includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode has an operating upper limit potential of 4.3 V or more based on metallic lithium. The positive electrode includes a positive electrode active material and a carbon-attached phosphate compound. The carbon-attached phosphate compound is a form in which conductive carbon is attached to at least a part of the surface of the inorganic phosphate compound having ion conductivity (preferably a form in which the surface of the inorganic phosphate compound is coated with conductive carbon). is there.
In a preferred embodiment, the inorganic phosphate compound is a phosphate of an alkali metal element and / or a Group 2 element (typically an alkaline earth metal element).

By setting the operating upper limit potential of the positive electrode to 4.3 V or higher, the potential difference (voltage) between the positive and negative electrodes can be increased, and a battery with a high energy density can be realized. Further, by providing the positive electrode with an inorganic phosphate compound, the following effects are obtained: (1) Decomposition reaction of a non-aqueous electrolyte (typically a supporting salt such as LiPF ₆ ) contained in the high potential state. (2) Hydrofluoric acid (HF) produced by hydrolysis of the supporting salt (for example, LiPF ₆ ) is trapped (trapped) in the inorganic phosphate compound, and the non-aqueous electrolyte solution At least one of the following: Accordingly, deterioration of the positive electrode active material (for example, elution of constituent elements) can be suppressed, and a highly durable (high capacity maintenance rate) battery can be realized. Furthermore, electronic conductivity can be imparted to the inorganic phosphate compound by attaching conductive carbon to the surface of the inorganic phosphate compound. As a result, it is possible to form a suitable conductive path (conductive path) in the positive electrode without increasing the content of the conductive material (while maintaining the same content as before), and to greatly reduce the internal resistance. it can.
Therefore, in the non-aqueous electrolyte secondary battery having the above-described configuration, excellent input / output characteristics can be realized in addition to high energy density and high durability.

It is a graph which shows the relationship between the adhesion amount of conductive carbon, and initial stage resistance.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention (for example, a general manufacturing process of a battery that does not characterize the present invention) are known in the art. It can be grasped as a design matter of those skilled in the art based on the above. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The non-aqueous electrolyte secondary battery disclosed herein includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. Hereinafter, each component will be described in order.

<Positive electrode>
The positive electrode of the non-aqueous electrolyte secondary battery disclosed here includes a positive electrode active material and a carbon-attached phosphate compound. As such a positive electrode, a positive electrode active material and a carbon-attached phosphoric acid compound, which are fixed on a positive electrode current collector together with a binder, a conductive material, etc., can be suitably used. As the positive electrode current collector, a conductive member made of a metal having good conductivity (for example, aluminum, nickel, etc.) can be suitably used.

  The positive electrode of the non-aqueous electrolyte secondary battery disclosed herein has an operating upper limit potential in the SOC (State of Charge) range of 0 to 100% of 4.3 V or more based on metallic lithium (preferably 4. 5V or more, more preferably 4.6V, or even 4.7V or more). In general, the operating potential becomes the highest between SOC 0% and 100% when the SOC is 100%. Usually, the operating upper limit potential of the positive electrode is grasped through the operating potential of the positive electrode at the SOC 100% (that is, the fully charged state). Can do. In the technology disclosed herein, typically, the positive electrode operating upper limit potential in the SOC range of 0 to 100% is 7.0 V or less (for example, 6.0 V or less, 5.5 V or less) based on metallic lithium. It can be preferably applied to an electrolyte secondary battery.

A positive electrode exhibiting such an operating upper limit potential can be realized by using a positive electrode active material having a maximum operating potential of 4.3 V or higher with respect to metallic lithium in a SOC range of 0 to 100%. Among them, it is preferable to use a positive electrode active material having an operating potential at 100% SOC exceeding 4.3 V based on metallic lithium, preferably 4.5 V or more, more preferably 4.6 V or more, and further 4.7 V or more. As a specific example, a lithium-manganese composite oxide having a spinel structure can be given. Among these, as a preferred embodiment, the following general formula (I):
_{Li x (Ni y Mn 2-} y-z M 1 z) O 4 + α A q (I)
The lithium nickel manganese composite oxide represented by these is mentioned. Here, M ¹ is any transition metal element or typical metal element other than Ni and Mn (for example, one or more selected from Ti, Cr, Fe, Co, Cu, Zn, and Al). obtain. Alternatively, it may be a metalloid element (for example, one or more selected from B, Si and Ge) and a nonmetallic element. X, y, and z are values satisfying 0.8 ≦ x ≦ 1.2, 0 <y, 0 ≦ z, and y + z <2 (typically y + z ≦ 1), and α is −0. .2 ≦ α ≦ 0.2, a value determined so as to satisfy the charge neutrality condition, and q is 0 ≦ q ≦ 1. In one preferred embodiment, y is 0.2 ≦ y ≦ 1.0 (more preferably 0.4 ≦ y ≦ 0.6, such as 0.45 ≦ y ≦ 0.55), and z is 0 ≦ 0. z <1.0 (for example, 0 ≦ z ≦ 0.3). Also, q is 0 ≦ q ≦ 1, and when q is greater than 0, A can be F or Cl.
A preferred example of the compound represented by the general formula (I) is LiNi _0.45 Fe _0.05 Mn _1.45 Ti _0.05 O ₄ .

  Generally, when a transition metal element (especially manganese) is contained in the constituent element of the positive electrode active material, the transition metal element may be eluted from the positive electrode active material in a high potential state. However, according to the technology disclosed herein, such a phenomenon can be prevented to a high degree, and a non-aqueous electrolyte secondary battery having both high energy density and high durability can be realized.

The positive electrode active material is preferably in the form of particles having an average particle size (secondary particle size) of about 5 to 20 μm (typically 10 to 15 μm). The specific surface area of the positive electrode active material is usually about 0.1 to 30 m ² / g. It is good that it is about 10 m ² / g. In the present specification, unless otherwise specified, the “average particle size” means particles corresponding to a cumulative frequency of 50% by volume from the side of fine particles having a small particle size in the volume-based particle size distribution based on the laser diffraction / light scattering method. Diameter (D ₅₀ , also referred to as median diameter). In the present specification, the “specific surface area” indicates a surface area (BET specific surface area) measured by a BET method using nitrogen gas (for example, a BET one-point method).

  The carbon-attached phosphate compound is formed by attaching conductive carbon to at least a part of the surface of an inorganic phosphate compound having ion conductivity. The carbon-attached phosphate compound having such a form is, for example, that an inorganic phosphate compound and conductive carbon measured in a predetermined ratio are put into an appropriate mixer and subjected to mechanochemical treatment under predetermined processing conditions. Can be produced. For such treatment, a conventionally used pulverization / mixing apparatus (for example, a jet mill, a planetary mixer, a homogenizer, a disper, etc.) can be used without particular limitation. In the mechanochemical treatment, the materials can be physically coupled (composited) by applying mechanical energy such as compressive force, shearing force, and frictional force to the powdery material (fine particles). That is, conductive carbon can be attached (typically in an island shape) to the surface of the inorganic phosphate compound. Preferably, the surface of the inorganic phosphate compound can be coated with conductive carbon (carbon coating).

As the inorganic phosphate compound, a substance having ion conductivity can be used without any particular limitation. One preferred example of such properties is an inorganic solid electrolyte material that is known to function as an electrolyte for an all-solid battery. For example, when the charge carrier is lithium ion (Li ⁺ ), a phosphate lithium ion conductor such as Li ₃ PO ₄ , LiPON (lithium phosphate oxynitride); Li _1.5 Al _0.5 Ge _{1. 5} (PO ₄ ) _{3 and} other NASICON type lithium ion conductors; perovskite type lithium ion conductors; thio-LISICON type lithium ion conductors; In the above example, the charge carrier is Li ⁺ , but other cations (typically, alkali metal ions such as Na ⁺ and K ⁺ , and alkaline earth metals such as Mg ²⁺ and Ca ^2+). Ion). Among them, phosphates of alkali metal elements and / or group 2 elements (typically alkaline earth metal elements), such as Na ₃ PO ₄ , K ₃ PO ₄ , Mg ₃ (PO ₄ ) ₂ , Ca ₃ Use of (PO ₄ ) ₂ or the like is preferable.
The inorganic phosphoric acid compound has an average particle size (secondary particle size) of 1 to 15 μm (typically from the viewpoint of suitably attaching conductive carbon and forming a good conductive path in the positive electrode active material layer. Is preferably in the form of particles of about 2 to 10 μm. The specific surface area of the inorganic phosphoric acid compound is suitably usually 5 to 50 m ² / g approximately, typically may is 10 to 40 m ² / g, for example 20 to 30 m ² / g approximately.

As the conductive carbon, a carbon material having high electronic conductivity can be used without particular limitation. Preferable examples include carbon black (typically acetylene black, ketjen black, furnace black), activated carbon, graphite, carbon fiber, carbon nanotube and the like.
In a preferred embodiment, when the inorganic phosphate compound is 100 parts by mass, the amount of the conductive carbon deposited is 5 parts by mass or more (typically 5 to 50 parts by mass, for example, 10 to 30 parts by mass). It is. By setting the adhesion amount to 5 parts by mass or more, high conductivity can be imparted to the inorganic phosphate compound. Moreover, since conductive carbon is bulky compared with an inorganic phosphoric acid compound, it is preferable to suppress to the minimum necessary. By setting the amount of adhesion to 30 parts by mass or less, it is possible to realize a higher density of the positive electrode active material layer.

  As the binder, for example, a polymer material such as a vinyl halide resin such as polyvinylidene fluoride (PVdF); a polyalkylene oxide such as polyethylene oxide (PEO); or the like can be suitably used. As the conductive material, for example, carbon materials such as carbon black (typically acetylene black and ketjen black), activated carbon, graphite, and carbon fiber can be suitably used. Note that the conductive material and the conductive carbon may be the same type of material (for example, both are carbon black) or different types of materials.

  The inorganic phosphate compound contained in the positive electrode is suitably 0.1 to 5 parts by mass with respect to 100 parts by mass of the positive electrode active material, and usually 0.5 to 2 parts by mass. By suppressing the addition amount of the inorganic phosphate compound having low electron conductivity to a low level, suitable electron conductivity can be imparted to the positive electrode. Thereby, the internal resistance of the positive electrode can be further reduced.

  The proportion of the positive electrode active material in the entire positive electrode active material layer is suitably about 50% by mass or more (typically 50 to 95% by mass), and usually about 80 to 95% by mass. The proportion of the inorganic phosphate compound in the entire positive electrode active material layer can be, for example, about 0.1 to 5% by mass, and usually about 0.5 to 2% by mass. The ratio of the binder to the whole positive electrode active material layer can be, for example, about 0.5 to 10% by mass, and usually about 1 to 5% by mass. The ratio of the sum of the conductive material and the conductive carbon in the entire positive electrode active material layer can be, for example, about 2 to 15% by mass, and usually about 5 to 9% by mass.

<Negative electrode>
As the negative electrode of the non-aqueous electrolyte secondary battery disclosed herein, a negative electrode active material layer is preferably formed by adhering a negative electrode active material together with a binder, a thickener, etc. on a negative electrode current collector. Can be used. As the negative electrode current collector, a conductive material made of a metal having good conductivity (for example, copper, nickel, etc.) can be suitably used. As the negative electrode active material, carbon materials such as graphite (graphite), non-graphitizable carbon (hard carbon), graphitizable carbon (soft carbon) and the like can be used, and among them, graphite can be preferably used. As the binder, styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE) or the like can be suitably used. As the thickener, a cellulose-based material of carboxymethyl cellulose (CMC) can be suitably used. As the negative electrode current collector, a conductive material made of a highly conductive metal (for example, copper) can be suitably used.

<Non-aqueous electrolyte>
The non-aqueous electrolyte solution of the non-aqueous electrolyte secondary battery disclosed herein typically exhibits a liquid state at normal temperature (for example, 25 ° C.), and is preferably always liquid within the operating temperature range (for example, −20 to 60 ° C.). Presents. As the nonaqueous electrolytic solution, a nonaqueous solvent containing a supporting salt (for example, a lithium salt in a lithium ion secondary battery) can be suitably used.
As the non-aqueous solvent, various organic solvents known to be usable for non-aqueous electrolyte secondary batteries can be used. Among them, those having high oxidation resistance (that is, high oxidative decomposition potential) are preferable. Preferable examples include fluorinated products (fluorine-containing nonaqueous solvent) such as carbonates, ethers, esters, nitriles, sulfones, and lactones. In particular, the use of fluorinated carbonate is preferred. Specifically, a fluorinated cyclic carbonate such as fluoroethylene carbonate (FEC); a fluorinated chain carbonate such as methyl (2,2,2-trifluoroethyl) carbonate (MTFEC); can be preferably used. Thereby, even if it is a case where the said high voltage positive electrode material (The positive electrode active material whose operation upper limit electric potential is 4.3 V or more high with respect to metallic lithium) is used, the battery excellent in durability is realizable.
As the supporting salt, lithium salts, sodium salts, magnesium salts, and the like can be used, and among them, lithium salts such as LiPF ₆ and LiBF ₄ can be preferably used.

<Applications of non-aqueous electrolyte secondary batteries>
The non-aqueous electrolyte secondary battery (so-called 5V class battery) disclosed herein can be used for various applications. However, the working potential of the positive electrode active material is increased and the constituent metal elements are eluted from the positive electrode current collector. Due to the effect of being suppressed and the conductivity in the positive electrode being increased, it is possible to achieve higher battery characteristics than in the past. For example, high energy density, high output density, and high durability can be combined. Therefore, taking advantage of such characteristics, it can be preferably used in applications requiring high energy density, high input / output density, and high durability. Examples of such applications include drive power supplies mounted on vehicles such as plug-in hybrid vehicles, hybrid vehicles, and electric vehicles.

Hereinafter, some examples relating to the present invention will be described, but the present invention is not intended to be limited to such examples.

<Preparation of positive electrode (Example 1)>
As the positive electrode active material, NiMn spinel (LiNi _0.5 Mn _1.5 O ₄ , Ti · Fe doped product, average particle size: 13.3 μm) was prepared. This positive electrode active material, acetylene black (AB, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “DENKA BLACK HS-100”) as a conductive material, and polyvinylidene fluoride (PVdF) as a binder were combined with LiNi _0.5 Mn _1.5 O ₄ : AB: PVdF = 89: 8: 3 was weighed so as to have a mass ratio and mixed with N-methyl-2-pyrrolidone (NMP) to prepare a slurry composition. This composition was applied to an aluminum foil (positive electrode current collector) and dried to form a positive electrode active material layer, thereby producing a positive electrode (Example 1).

<Preparation of positive electrode (Example 2)>
Commercially available Li ₃ PO ₄ (manufactured by Wako Pure Chemical Industries, average particle size: 6.1 μm, specific surface area: 29 m ² / g) was prepared as the inorganic phosphate compound. This Li ₃ PO ₄ (uncoated Li ₃ PO ₄ ) and the positive electrode active material were mixed at a mass ratio of 1: 100. Next, such a mixture, acetylene black (AB) as a conductive material, and polyvinylidene fluoride (PVdF) as a binder (LiNi _0.5 Mn _1.5 O ₄ + uncoated Li ₃ PO ₄ ): AB: PVdF = 89: 8: 3 was weighed so as to have a mass ratio and mixed with NMP to prepare a slurry-like composition. And this composition was apply | coated to aluminum foil (positive electrode collector), it was made to dry and a positive electrode active material layer was formed, and the positive electrode (Example 2) was produced.

<Preparation of positive electrode (Example 3)>
(LiNi _0.5 Mn _1.5 O ₄ + Uncoated Li ₃ PO ₄ ): A positive electrode (Example 3) was produced in the same manner as in Example 2 except that AB: PVdF = 87: 10: 3.

<Preparation of positive electrode (Examples 4 to 9)>
First, Li ₃ PO ₄ and acetylene black (AB, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denka Black HS-100”) as conductive carbon are converted into a model “Nobilta NOB-MINI” manufactured by Hosokawa Micron. The coating was applied for 10 minutes under the condition of a rotational speed of 5000 rpm. In addition, conductive carbon (AB) is 1 part by mass, 3 parts by mass, 5 parts by mass, 10 parts by mass, 20 parts by mass, and 30 parts by mass with respect to 100 parts by mass of the inorganic phosphate compound (Li ₃ PO ₄ ). The ratio was added. In this way, carbon-attached phosphate compounds (Examples 4 to 9) having conductive carbon attached to the surface of the inorganic phosphate compound were obtained.
Next, positive electrodes (Examples 4 to 9) were prepared in the same manner as in Example 2 except that the prepared carbon-attached phosphate compound was used instead of the uncoated Li ₃ PO ₄ .

<Preparation of negative electrode>
Graphite (C) as the negative electrode active material, carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) as the binder are weighed so as to have a mass ratio of C: CMC: SBR = 98: 1: 1. A slurry-like composition was prepared by mixing with exchange water. This composition was applied to a copper foil (negative electrode current collector) and dried to form a negative electrode active material layer.

<Construction of non-aqueous electrolyte secondary battery>
The produced positive electrode and negative electrode were laminated via a separator to produce electrode bodies (Examples 1 to 9). As the separator, a porous film having a three-layer structure made of polyethylene (PE) / polypropylene (PP) / polyethylene (PE) was used. Further, a mixed solvent containing monofluoroethylene carbonate (MFEC) as a cyclic carbonate and trifluorodimethyl carbonate (TFDMC) as a chain carbonate in a volume ratio of 1: 1, and LiPF ₆ as a supporting salt are 1. It melt | dissolved so that it might become a 0 mol / L density | concentration, and prepared the non-aqueous electrolyte. The electrode body and the non-aqueous electrolyte were accommodated in a battery case made of laminate, and then sealed to construct a non-aqueous electrolyte secondary battery (Examples 1 to 9). In Table 1, the ratio of the carbon material to the entire positive electrode active material layer represents the sum of the conductive carbon (acetylene black) coated on the surface of Li ₃ PO ₄ and the carbon material added as a conductive material (acetylene black). ing.

<Conditioning process>
The battery thus constructed (Examples 1 to 9) was subjected to conditioning treatment by repeating the following charge / discharge patterns (1) and (2) for 3 cycles under a temperature environment of 25 ° C.
(1) After charging at a constant current (CC) at a rate of 1/3 C until the positive electrode potential becomes 4.9 V, the battery is paused for 10 minutes.
(2) CC discharge at a rate of 1/3 C until the positive electrode potential becomes 3.5 V, and then rest for 10 minutes.

<Initial resistance>
The batteries after the conditioning treatment (Examples 1 to 9) were subjected to CC charging at a rate of 1/3 C under a temperature environment of 25 ° C. until the SOC reached 60%. CC discharge was performed at 1C, 3C, 5C, and 10C rates on the battery adjusted to an SOC of 60%, and the amount of voltage drop for 10 seconds from the start of discharge was measured. The IV resistance (Ω) was calculated by dividing the measured voltage drop value (V) by the corresponding current value, and the average value was taken as the initial resistance. The results are shown in Table 1. FIG. 1 shows the relationship between the carbon coat amount and the initial resistance.

<High temperature durability test>
Next, after the batteries (Examples 1 to 9) after the initial performance measurement were left in a thermostatic chamber set at a temperature of 60 ° C. for 2 hours or more, the following charge / discharge operations (1) and (2) were performed in 200. The cycle was repeated.
(1) After charging CC to 4.9V at a rate of 2C, pause for 10 minutes.
(2) After CC discharge to 3.5 V at a rate of 2C, pause for 10 minutes.
The capacity retention rate (%) was calculated as the ratio of the discharge capacity after the high-temperature endurance test to the discharge capacity at the first cycle ((discharge capacity at the 200th cycle / discharge capacity at the first cycle) × 100 (%)). The results are shown in Table 1.

As is clear from Table 1, in Example 1 in which the positive electrode did not contain Li ₃ PO ₄ , the capacity retention rate was relatively low and the durability was insufficient. In Example 2 in which uncoated Li ₃ PO ₄ was mixed with the positive electrode, durability was significantly improved as compared with Example 1, but an increase in initial resistance was observed as a contradiction. This is considered due to the low electronic conductivity of Li ₃ PO ₄ . In Example 3 in which the proportion of the conductive material was increased, the resistance was slightly reduced, but the effect was small. From this, it has been found that the increase in resistance caused by Li ₃ PO ₄ is difficult to solve by simply increasing the amount of conductive material added. In Example 3, the ratio of the carbon material with respect to the whole positive electrode active material layer was further increased, and there was a concern that the energy density was lowered due to this.

On the other hand, as shown in Table 1 and FIG. 1, in Examples 4 to 9 in which the positive electrode contains carbon-attached Li ₃ PO ₄ , the durability is high and the resistance decreases as the proportion of AB (carbon coating amount) increases. The effect of In particular, the initial resistance is relatively low at 2Ω or less by setting the amount of AB to be 5 parts by mass or more (in other words, 1.68 mg / m ² or more with respect to the specific surface area of Li ₃ PO ₄ ). I was able to suppress it. From this, it was found that according to the technique disclosed herein, the resistance of the positive electrode can be efficiently reduced without greatly increasing the ratio of the carbon material to the entire positive electrode active material layer.
From the above results, it was found that a non-aqueous electrolyte secondary battery having excellent durability and low resistance can be realized by including a carbon-attached phosphate compound in the positive electrode. This result shows the technical significance of the present invention.

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

Claims (1)

A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte,
The positive electrode is
The operating upper limit potential is 4.3 V or more with respect to metallic lithium,
Non-aqueous electrolysis comprising: a positive electrode active material; and a carbon-attached phosphate compound that is a carbon-attached phosphate compound and has an ion conductivity and is formed by attaching conductive carbon to at least a part of the surface of the inorganic phosphate compound. Liquid secondary battery.

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