Secondary battery electrode and secondary battery

Abstract

This secondary battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes a positive electrode active material and a carbon- and nitrogen-containing metal compound. The positive electrode active material includes sulfur, and the carbon- and nitrogen-containing metal compound includes carbon, nitrogen, and a metal element as constitutional elements.

Description

[Technical Field]

[0001] The present technology relates to an electrode for a secondary battery and a secondary battery. [Background technology]

[0002] Due to the widespread use of various electronic devices such as mobile phones, secondary batteries have been developed as a power source that is small, lightweight, and has high energy density. These secondary batteries include electrodes (secondary battery electrodes) and an electrolyte, and the electrodes contain an active material.

[0003] In particular, secondary batteries using sulfur as a positive electrode active material are known, and various studies have been conducted on the configuration of such secondary batteries. Specifically, the positive electrode active material contains titanium oxide (TiO2) together with sulfur (see Non-Patent Document 1). To obtain this positive electrode active material, sulfur and titanium oxide are mixed in a weight ratio of 7:3, and then the mixture of sulfur and titanium oxide is heated. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] BingDing(2013), “Encapsulating sulfur into mesoporous TiO2 host as a high performance cathode for lithium-sulfur battery”, Electrochimica Acta, vol.107, p78-p84 Summary of the Invention

[0005] Although various studies have been conducted on the configuration of secondary batteries, the battery characteristics of the secondary batteries are still insufficient and there is room for improvement.

[0006] There is a demand for a secondary battery electrode and a secondary battery that are capable of achieving excellent battery characteristics.

[0007] An electrode for a secondary battery according to one embodiment of the present technology includes a positive electrode active material and a carbon-nitrogen-containing metal compound, the positive electrode active material containing sulfur, and the carbon-nitrogen-containing metal compound containing carbon, nitrogen, and a metal element as constituent elements.

[0008] A secondary battery according to an embodiment of the present technology includes a positive electrode, a negative electrode, and an electrolyte solution, and the positive electrode has a configuration similar to the configuration of the electrode for a secondary battery according to the embodiment of the present technology described above.

[0009] According to an electrode for a secondary battery of one embodiment of the present technology, the electrode for a secondary battery includes a positive electrode active material and a carbon-nitrogen-containing metal compound, the positive electrode active material includes sulfur, and the carbon-nitrogen-containing metal compound includes carbon, nitrogen, and a metal element as constituent elements. Therefore, a secondary battery having excellent battery characteristics can be realized by using the electrode for a secondary battery.

[0010] Furthermore, according to the secondary battery of one embodiment of the present technology, the battery is provided with a positive electrode, and the positive electrode has a configuration similar to that of the electrode of the embodiment of the present technology described above, so that excellent battery characteristics can be obtained.

[0011] Note that the effects of the present technology are not necessarily limited to the effects described here, but may be any of a series of effects related to the present technology described below. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view illustrating a configuration of a secondary battery according to an embodiment of the present technology. [Figure 2] FIG. 2 is a cross-sectional view illustrating the configuration of the battery element shown in FIG. [Figure 3] 10 is a cross-sectional view illustrating the configuration of a secondary battery according to Modification 1. FIG. [Figure 4] FIG. 1 is a block diagram illustrating a configuration of an application example of a secondary battery. [Figure 5] FIG. 2 is a cross-sectional view illustrating the configuration of a test secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present technology will be described in detail with reference to the drawings. The description will be made in the following order. 1. Secondary battery 1-1.Configuration 1-2.Operation 1-3. Manufacturing method 1-4. Action and effects 2. Variations 3. Uses of secondary batteries

[0014] <1. Secondary battery> First, a secondary battery according to an embodiment of the present technology will be described.

[0015] Note that the electrode for a secondary battery according to one embodiment of the present technology is a part of the secondary battery described herein, that is, a component of the secondary battery, and therefore the electrode for the secondary battery will be described below.

[0016] This secondary battery is a secondary battery that obtains battery capacity by utilizing the absorption and desorption of an electrode reactant, and includes a positive electrode, a negative electrode, and an electrolyte. In this secondary battery, the secondary battery electrode may be used as a positive electrode, a negative electrode, or both a positive electrode and a negative electrode. The type of electrode reactant is not particularly limited.

[0017] In the following, an example will be given in which the secondary battery electrode is used as a positive electrode and the electrode reactant is lithium. The positive electrode contains a positive electrode active material that absorbs and releases lithium, and the positive electrode active material contains sulfur. In this case, lithium is absorbed and released in an ionic state.

[0018] <1-1.Configuration> Fig. 1 shows a perspective view of a secondary battery, and Fig. 2 shows a cross-sectional view of the battery element 20 shown in Fig. 1. However, Fig. 1 shows a state in which the exterior film 10 and the battery element 20 are separated from each other, and the cross section of the battery element 20 along the XZ plane is shown by a broken line.

[0019] As shown in FIGS. 1 and 2, this secondary battery includes an exterior film 10, a battery element 20, a positive electrode lead 31, a negative electrode lead 32, and sealing films 41 and .

[0020] The secondary battery described here is a so-called laminate film type secondary battery, since it uses a flexible or pliable exterior film 10 as an exterior member for housing the battery element 20 inside, as described above.

[0021] [Exterior film] 1, the exterior film 10 has a sealed bag-like structure with the battery element 20 housed therein. As a result, the exterior film 10 houses a positive electrode 21, a negative electrode 22, a separator 23, and an electrolyte solution, which will be described later.

[0022] Here, the exterior film 10 is a single film-like member that is folded in a folding direction F. The exterior film 10 is provided with a recessed portion 10U (so-called deep drawn portion) for accommodating the battery element 20.

[0023] Specifically, the exterior film 10 is a three-layer laminate film in which a fusion layer, a metal layer, and a surface protection layer are laminated in this order from the inside out, and when the exterior film 10 is folded, the outer peripheral edges of the opposing fusion layers are fused to each other. The fusion layer contains a polymer compound such as polypropylene. The metal layer contains a metal material such as aluminum. The surface protection layer contains a polymer compound such as nylon.

[0024] However, the configuration (number of layers) of the exterior film 10 is not particularly limited, and may be one layer, two layers, or four or more layers.

[0025] [Battery element] The battery element 20 is housed inside the exterior film 10. The battery element 20 is a so-called power generating element, and as shown in Figures 1 and 2, includes a positive electrode 21, a negative electrode 22, a separator 23, and an electrolyte (not shown).

[0026] Here, battery element 20 is a so-called wound electrode body. That is, positive electrode 21 and negative electrode 22 are wound around winding axis P while facing each other with separator 23 interposed therebetween. As is clear from FIG. 1 , winding axis P is a virtual axis extending in the Y-axis direction.

[0027] There are no particular limitations on the three-dimensional shape of battery element 20. Here, battery element 20 has a flat three-dimensional shape, and therefore the shape of a cross section of battery element 20 intersecting winding axis P (cross section along the XZ plane) is a flat shape defined by major axis J1 and minor axis J2.

[0028] The major axis J1 is an imaginary axis extending in the X-axis direction and has a length greater than that of the minor axis J2. The minor axis J2 is an imaginary axis extending in the Z-axis direction intersecting the X-axis direction and has a length less than that of the major axis J1. Here, the three-dimensional shape of the battery element 20 is a flattened cylinder, and therefore the cross-sectional shape of the battery element 20 is a flattened, approximately elliptical shape.

[0029] (positive electrode) The positive electrode 21 is an example of an electrode for a secondary battery. As shown in Fig. 2, the positive electrode 21 includes a positive electrode current collector 21A and a positive electrode active material layer 21B.

[0030] The positive electrode current collector 21A has a pair of surfaces on which the positive electrode active material layer 21B is provided, and supports the positive electrode active material layer 21B. The positive electrode current collector 21A contains a conductive material such as a metal material, and a specific example of the conductive material is aluminum.

[0031] The positive electrode active material layer 21B contains a positive electrode active material and a carbon / nitrogen-containing metal compound, each of which is in the form of a plurality of particles (so-called powder), and thus the positive electrode active material and the carbon / nitrogen-containing metal compound are dispersed in the positive electrode active material layer 21B.

[0032] Here, the positive electrode active material layer 21B is provided on both sides of the positive electrode current collector 21A. However, the positive electrode active material layer 21B may be provided on only one side of the positive electrode current collector 21A. The method for forming the positive electrode active material layer 21B is not particularly limited, and specifically, it may be one or more of coating methods or the like.

[0033] The positive electrode active material is a material that absorbs and releases lithium, and as described above, contains sulfur.

[0034] The carbon-nitrogen-containing metal compound contains carbon, nitrogen, and a metal element as constituent elements. The carbon-nitrogen-containing metal compound may be of one type or two or more types.

[0035] More specifically, the carbon-nitrogen-containing metal compound is a compound in which carbon, nitrogen, and a metal element are bonded to each other, and the form in which the carbon, nitrogen, and metal atoms are bonded to each other in the carbon-nitrogen-containing metal compound (hereinafter referred to as "bonding form") is not particularly limited. That is, as long as the carbon-nitrogen-containing metal compound contains carbon, nitrogen, and a metal element as constituent elements, the carbon, nitrogen, and metal atoms may be bonded in any manner within the carbon-nitrogen-containing metal compound.

[0036] The reason why the positive electrode active material layer 21B contains the carbon / nitrogen-containing metal compound is that the utilization efficiency of the positive electrode active material (sulfur) is improved compared to when the positive electrode active material layer 21B does not contain the carbon / nitrogen-containing metal compound, thereby improving the diffusibility of the electrode reactant (lithium). The utilization efficiency described here is the so-called Coulomb efficiency (charge / discharge efficiency).

[0037] In this case, particularly, if the content of the carbon / nitrogen-containing metal compound in the positive electrode active material layer 21B is made sufficiently small within a range in which the Coulomb efficiency is improved, the energy density per weight of the positive electrode 21 is ensured even if the positive electrode active material layer 21B contains the carbon / nitrogen-containing metal compound.

[0038] This ensures that lithium can be diffused in the positive electrode 21, and therefore reduces the decrease in battery capacity even when charging and discharging are repeated.

[0039] As mentioned above, the bonding type of the carbon-nitrogen-containing metal compound is not particularly limited, but specific examples of the bonding type of carbon and nitrogen include cyanamide (>NC≡N) and carbodiimide (-N=C=N-). Specific examples of the carbon-nitrogen-containing metal compound include metal cyanamide and metal carbodiimide, because this sufficiently improves the Coulomb efficiency. Of course, the carbon-nitrogen-containing metal compound may contain only metal cyanamide, only metal carbodiimide, or both metal cyanamide and metal carbodiimide.

[0040] The type of metal element is not particularly limited. Therefore, the type of metal element may be one type or two or more types. Specific examples of metal elements include zinc (Zn), calcium (Ca), lithium (Li), sodium (Na), potassium (K), cesium (Cs), strontium (Sr), barium (Ba), magnesium (Mg), silicon (Si), titanium (Ti), lead (Pb), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), yttrium (Y), silver (Ag), and cadmium (Cd). , praseodymium (Pr), neodymium (Nd), samarium (Sm), eurobium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), strontium zinc (SrZn), lithium aluminum (LiAl), lithium indium (LiIn), and lithium ytterbium (LiYb).

[0041] Among these, zinc and calcium are preferred as the metal element, because they further improve the Coulomb efficiency. Of course, the metal element may contain only zinc, only calcium, or both zinc and calcium.

[0042] Thus, when the carbon / nitrogen-containing metal compound is a metal cyanamide, specific examples of the metal cyanamide are zinc cyanamide and calcium cyanamide, etc. Furthermore, when the carbon / nitrogen-containing metal compound is a metal carbodiimide, specific examples of the metal carbodiimide are zinc carbodiimide and calcium carbodiimide, etc. Note that when the carbon / nitrogen-containing metal compound contains both a metal cyanamide and a metal carbodiimide, the main component may be either a metal cyanamide or a metal carbodiimide.

[0043] The content of the carbon / nitrogen-containing metal compound in the positive electrode active material layer 21B is not particularly limited and can be set arbitrarily. However, as described above, in order to ensure the energy density per weight of the positive electrode 21, it is preferable that the content of the carbon / nitrogen-containing metal compound in the positive electrode active material layer 21B be sufficiently smaller than the content of the positive electrode active material in the positive electrode active material layer 21B.

[0044] The positive electrode active material layer 21B may further contain one or more of other materials such as a positive electrode conductive agent and a positive electrode binder.

[0045] The positive electrode conductive agent contains one or more conductive materials such as carbon materials, metal materials, and conductive polymer compounds. Specific examples of carbon materials include activated carbon, graphite, carbon black, acetylene black, and ketjen black.

[0046] The positive electrode binder contains one or more of the following materials: synthetic rubber, polymer compound, etc. Specific examples of synthetic rubber include styrene-butadiene rubber, fluorine-containing rubber, and ethylene-propylene-diene. Specific examples of polymer compounds include polyvinylidene fluoride, polyimide, and carboxymethyl cellulose.

[0047] In particular, it is preferable that the positive electrode active material layer 21B contains a positive electrode conductive agent, and that the positive electrode conductive agent contains a carbon material, because the conductivity of the positive electrode active material layer 21B is sufficiently improved, and the coulomb efficiency is therefore sufficiently improved.

[0048] (Negative electrode) As shown in FIG. 2, the negative electrode 22 contains a negative electrode active material. This negative electrode active material contains an alkali metal material, which is a material containing one or more types of alkali metal elements as constituent elements. However, the type of alkali metal element may be only one type, or two or more types. Furthermore, the alkali metal material may be a simple substance, an alloy, a compound, or two or more types thereof.

[0049] Here, the alkali metal material includes an alkali metal (a so-called elemental alkali metal) because sufficient battery capacity can be obtained. However, the "elemental alkali metal" described here may contain any amount of impurities, so the purity of the "elemental alkali metal" is not necessarily limited to 100%.

[0050] The type of alkali metal is not particularly limited, but specific examples include lithium, sodium, and potassium.

[0051] Among these, as described above, the alkali metal is preferably lithium, because this further improves the Coulomb efficiency. A secondary battery in which the positive electrode 21 contains sulfur as a positive electrode active material and the negative electrode 22 contains lithium as a negative electrode active material is a so-called lithium-sulfur secondary battery. In this case, since the negative electrode 22 is a lithium metal plate, the negative electrode 22 may contain lithium metal as a negative electrode active material (alkali metal material).

[0052] (separator) 2, the separator 23 is an insulating porous film interposed between the positive electrode 21 and the negative electrode 22, and allows lithium to pass through in an ionic state while preventing the occurrence of a short circuit due to contact between the positive electrode 21 and the negative electrode 22. The separator 23 contains a polymer compound such as polyethylene.

[0053] (electrolyte) The electrolyte is a liquid electrolyte and is impregnated into each of the positive electrode 21 and the separator 23. The electrolyte contains a solvent and an electrolyte salt.

[0054] The solvent contains one or more types of non-aqueous solvents (organic solvents), and the electrolyte containing the non-aqueous solvent is a so-called non-aqueous electrolyte.

[0055] The non-aqueous solvent is an ester, an ether, or the like, and more specifically, is one or more of a carbonate ester compound, a carboxylic acid ester compound, and a lactone compound, because the dissociation of the electrolyte salt and the mobility of ions are improved.

[0056] The carbonate ester compounds include cyclic carbonate esters and chain carbonate esters. Specific examples of the cyclic carbonate esters include ethylene carbonate and propylene carbonate, and specific examples of the chain carbonate esters include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0057] The carboxylic acid ester compound is a chain carboxylic acid ester, etc. Specific examples of the chain carboxylic acid ester include ethyl acetate, ethyl propionate, propyl propionate, and ethyl trimethylacetate.

[0058] The lactone compound is a lactone, etc. Specific examples of lactones include γ-butyrolactone and γ-valerolactone.

[0059] The ethers may be 1,2-dimethoxyethane, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, or the like.

[0060] The non-aqueous solvent is one or more of unsaturated cyclic carbonates, fluorinated cyclic carbonates, sulfonates, phosphates, acid anhydrides, nitrile compounds, isocyanate compounds, etc. This is because the dissociation of the electrolyte salt and the mobility of ions are similarly improved.

[0061] Specific examples of unsaturated cyclic carbonates include vinylene carbonate, vinylethylene carbonate, and methyleneethylene carbonate. Specific examples of fluorinated cyclic carbonates include monofluoroethylene carbonate and difluoroethylene carbonate. Specific examples of sulfonic acid esters include propane sultone and propene sultone. Specific examples of phosphate esters include trimethyl phosphate and triethyl phosphate. Specific examples of acid anhydrides include succinic anhydride, 1,2-ethanedisulfonic anhydride, and 2-sulfobenzoic anhydride. Specific examples of nitrile compounds include succinonitrile. Specific examples of isocyanate compounds include hexamethylene diisocyanate.

[0062] Of course, the composition of the non-aqueous solvent is not particularly limited as long as it contains one or more of the above-mentioned series of non-aqueous solvent candidates, and can be set arbitrarily.

[0063] The electrolyte salt contains one or more types of light metal salts such as lithium salts.

[0064] Specific examples of lithium salts include lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium trifluoromethanesulfonate (LiCFSO), lithium bis(fluorosulfonyl)imide (LiN(FSO)), lithium bis(trifluoromethanesulfonyl)imide (LiN(CFSO)), lithium tris(trifluoromethanesulfonyl)methide (LiC(CFSO)), lithium bis(oxalato)borate (LiB(CO)), lithium monofluorophosphate (LiPFO), and lithium difluorophosphate (LiPFO). These salts are used because they can provide high battery capacities.

[0065] The content of the electrolyte salt is not particularly limited, but specifically, it is 0.3 mol / kg to 3.0 mol / kg relative to the solvent, because high ionic conductivity can be obtained.

[0066] [Positive lead] 1 and 2, the positive electrode lead 31 is a positive electrode wiring connected to the positive electrode current collector 21A of the positive electrode 21, and is led out of the exterior film 10. The positive electrode lead 31 contains a conductive material such as a metal material, and a specific example of the conductive material is aluminum. The positive electrode lead 31 has a shape such as a thin plate or a mesh.

[0067] [Negative lead] As shown in FIGS. 1 and 2 , the negative electrode lead 32 is a negative electrode wiring connected to the negative electrode 22 and is led out of the exterior film 10. Here, the lead-out direction of the negative electrode lead 32 is the same as the lead-out direction of the positive electrode lead 31. The negative electrode lead 32 contains a conductive material such as a metal material, and a specific example of the conductive material is copper. The details of the shape of the negative electrode lead 32 are the same as the details of the shape of the positive electrode lead 31.

[0068] [Sealing film] The sealing film 41 is inserted between the exterior film 10 and the positive electrode lead 31, and the sealing film 42 is inserted between the exterior film 10 and the negative electrode lead 32. However, one or both of the sealing films 41 and 42 may be omitted.

[0069] The sealing film 41 is a sealing member that prevents outside air and the like from entering the inside of the exterior film 10. This sealing film 41 contains a polymer compound such as polyolefin that has adhesiveness to the positive electrode lead 31, and a specific example of the polymer compound is polypropylene.

[0070] The configuration of the sealing film 42 is the same as the configuration of the sealing film 41, except that the sealing film 42 is a sealing member that has adhesiveness to the negative electrode lead 32. That is, the sealing film 42 contains a polymer compound such as polyolefin that has adhesiveness to the negative electrode lead 32.

[0071] <1-2. Operation> This secondary battery operates in the battery element 20 as follows.

[0072] During discharge, lithium is released from the negative electrode 22 and is absorbed into the positive electrode 21 via the electrolyte. On the other hand, during charge, lithium is released from the positive electrode 21 and is absorbed into the negative electrode 22 via the electrolyte. During both discharge and charge, lithium is absorbed and released in an ionic state.

[0073] <1-3. Manufacturing method> When manufacturing a secondary battery, the positive electrode 21 is fabricated and an electrolyte solution is prepared according to the procedure described below as an example. Then, the positive electrode 21, the negative electrode 22, and the electrolyte solution are used to assemble a secondary battery, and a stabilization process is performed on the assembled secondary battery.

[0074] [Preparation of positive electrode] First, a sulfur-containing cathode active material, a carbon / nitrogen-containing metal compound, a cathode binder, and a cathode conductor are mixed together to form a cathode mixture. Next, the cathode mixture is poured into a solvent to prepare a paste-like cathode mixture slurry. This solvent may be an aqueous solvent or an organic solvent. Next, the cathode mixture slurry is applied to both sides of the cathode current collector 21A to form the cathode active material layer 21B. Finally, the cathode active material layer 21B may be compression-molded using a roll press or the like. In this case, the cathode active material layer 21B may be heated, or the compression molding may be repeated multiple times. This results in the formation of the cathode active material layer 21B on both sides of the cathode current collector 21A, thereby producing the cathode 21.

[0075] [Preparation of electrolyte] An electrolyte salt is added to a solvent, whereby the electrolyte salt is dispersed or dissolved in the solvent, thereby preparing an electrolytic solution.

[0076] [Secondary battery assembly] First, the negative electrode 22 containing an alkali metal is prepared. In this case, a lithium metal plate or the like is used as the negative electrode 22. Next, the positive electrode lead 31 is connected to the positive electrode current collector 21A of the positive electrode 21 using a joining method such as welding, and the negative electrode lead 32 is connected to the negative electrode 22 using a joining method such as welding.

[0077] Next, the positive electrode 21 and the negative electrode 22 are stacked together with the separator 23 interposed therebetween, and then the positive electrode 21, the negative electrode 22, and the separator 23 are wound together to produce a wound body (not shown). This wound body has a configuration similar to that of the battery element 20, except that the positive electrode 21, the negative electrode 22, and the separator 23 are not impregnated with an electrolyte solution. Next, the wound body is pressed using a press or the like to form the wound body into a flat shape.

[0078] Next, after the roll is housed inside the recess 10U, the exterior film 10 (adhesive layer / metal layer / surface protection layer) is folded to make the exterior films 10 face each other. Next, the outer peripheral edges of two sides of the opposing adhesive layers are joined together using an adhesive method such as heat fusion, thereby housing the roll inside the bag-shaped exterior film 10.

[0079] Finally, an electrolyte solution is poured into the bag-shaped exterior film 10, and then the outer peripheral edges of the remaining sides of the opposing fusion layers are joined together using an adhesive method such as heat fusion. In this case, a sealing film 41 is inserted between the exterior film 10 and the positive electrode lead 31, and a sealing film 42 is inserted between the exterior film 10 and the negative electrode lead 32.

[0080] As a result, the wound body is impregnated with the electrolyte solution, forming a wound electrode body, the battery element 20. The battery element 20 is then sealed inside the bag-shaped exterior film 10, and a secondary battery is assembled.

[0081] [Stabilization of secondary batteries] The assembled secondary battery is charged and discharged. Various conditions, such as the ambient temperature, the number of charge / discharge cycles (number of cycles), and the charge / discharge conditions, can be set as desired. This electrochemically stabilizes the states of the positive electrode 21 and the negative electrode 22, completing the secondary battery.

[0082] <1-4. Actions and Effects> According to this secondary battery, the positive electrode 21 contains a positive electrode active material and a carbon-nitrogen-containing metal compound, the positive electrode active material contains sulfur, and the carbon-nitrogen-containing metal compound contains carbon, nitrogen, and a metal element as constituent elements.

[0083] In this case, as described above, the utilization efficiency (Coulomb efficiency) of the positive electrode active material (sulfur) is improved compared to when the positive electrode 21 does not contain a carbon-nitrogen-containing metal compound, and the diffusibility of the electrode reactant (lithium) is improved. This ensures the diffusibility of lithium, and suppresses the decrease in battery capacity even when the secondary battery is repeatedly charged and discharged. Therefore, sufficient battery capacity can be obtained even when the secondary battery is used repeatedly, and excellent battery characteristics can be obtained.

[0084] In the secondary battery of Non-Patent Document 1, the mixing ratio (weight ratio) of sulfur to titanium oxide is sulfur:titanium oxide=70:30, so the energy density per weight of the positive electrode 21 is 400 mAh / g.

[0085] In contrast, in the secondary battery of this embodiment, the above-mentioned advantages can be obtained even if the mixing ratio (weight ratio) of sulfur to the carbon / nitrogen-containing metal compound (e.g., zinc cyanamide) is sulfur:carbon / nitrogen-containing metal compound=10:1.

[0086] Moreover, in the secondary battery of this embodiment, the energy density per weight of the positive electrode 21 is 556 mAh / g when the discharge current and charge current are each 0.05 C, and the energy density per weight of the positive electrode 21 is 515 mAh / g when the discharge current and charge current are each 0.2 C. The currents (0.05 C and 0.2 C) described here will be described in detail later.

[0087] Therefore, in the secondary battery of this embodiment, unlike the secondary battery of Non-Patent Document 1, excellent battery characteristics can be obtained while the energy density per weight of the positive electrode 21 is ensured.

[0088] In particular, if the carbon / nitrogen-containing metal compound contains one or both of a metal cyanamide and a metal carbodiimide, the Coulomb efficiency is sufficiently improved, and thus a higher effect can be obtained. In this case, if the metal element contains one or both of zinc and calcium, the Coulomb efficiency is stably improved, and thus an even higher effect can be obtained.

[0089] Furthermore, if the negative electrode 22 contains an alkali metal, the absorption and release of lithium can be utilized to stably obtain sufficient battery capacity, thereby achieving a higher effect. In this case, if the alkali metal contains lithium, the coulomb efficiency is further improved, thereby achieving an even higher effect.

[0090] Furthermore, if the positive electrode 21 contains a positive electrode conductive agent, and the positive electrode conductive agent contains a carbon material, the coulomb efficiency is improved sufficiently, and a higher effect can be obtained.

[0091] Furthermore, if the secondary battery is a lithium-sulfur secondary battery, a sufficient battery capacity can be stably obtained by utilizing the absorption and desorption of lithium, and therefore a greater effect can be obtained.

[0092] In addition, the positive electrode 21 includes a positive electrode active material and a carbon-nitrogen-containing metal compound, the positive electrode active material contains sulfur, and the carbon-nitrogen-containing metal compound contains carbon, nitrogen, and a metal element as constituent elements. Therefore, as described above, the Coulomb efficiency is improved, and accordingly, the decrease in battery capacity is suppressed even when charging and discharging are repeated, thereby realizing a secondary battery with excellent battery characteristics.

[0093] <2. Modifications> The configuration of the secondary battery can be modified as appropriate, as described below, although the series of modifications described below may be combined with each other.

[0094] [Variation 1] 3 shows a cross-sectional configuration of the secondary battery in Modification 1, and more specifically, shows an enlarged cross-sectional configuration of the positive electrode conductive agent 212 contained in the positive electrode active material layer 21B of the positive electrode 21. In the following, FIG. 2 will be referred to together with FIG. 3 as appropriate.

[0095] 2 and 3, the positive electrode active material layer 21B includes a positive electrode active material 211 and a positive electrode conductive agent 212. The positive electrode active material 211 and the positive electrode conductive agent 212 are each in the form of a plurality of particles (powder). However, only one positive electrode conductive agent 212 is shown in FIG.

[0096] The positive electrode conductive agent 212 contains a carbon material, more specifically, a carbon material having a plurality of pores 212K. A specific example of a carbon material having a plurality of pores 212K is activated carbon. As a result, the positive electrode conductive agent 212 has a plurality of pores 212K, and the positive electrode active material 211 is inserted into the plurality of pores 212K. As described above, the positive electrode active material 211 contains sulfur.

[0097] In this case, the positive electrode active material 211 may be inserted into only some of the pores 212K among the plurality of pores 212K, or may be inserted into all of the plurality of pores 212K. Furthermore, the positive electrode active material 211 may be present in the entire interior of one pore 212K, and therefore the positive electrode active material 211 may be filled in the interior of that pore 212K, or the positive electrode active material 211 may be present in only a portion of the interior of that one pore 212K, and therefore the positive electrode active material 211 may partially enter the interior of that pore 212K.

[0098] The procedure for forming the positive electrode conductive agent 212 in which the positive electrode active material 211 is inserted into the plurality of pores 212K is as follows.

[0099] First, powdered positive electrode conductive agent 212 having a plurality of pores 212K is decomposed. In this case, metal balls for decomposition and the powdered positive electrode conductive agent 212 may be mixed together, and then the metal balls may be used to stir the positive electrode conductive agent 212. Next, the decomposed positive electrode conductive agent 212 is mixed with powdered positive electrode active material 211 to obtain a mixture. Finally, the mixture is heated in an inert atmosphere. In this case, argon gas or the like is used as the inert gas. Heating conditions such as heating temperature and heating time can be set as desired. As a result, the positive electrode active material 211 is inserted into the plurality of pores 212K.

[0100] In this case, the coulomb efficiency is improved, and the diffusibility of lithium is further improved, so that the decrease in battery capacity is further suppressed even when charging and discharging are repeated, thereby achieving a greater effect.

[0101] [Variation 2] A porous film separator 23 was used. However, although not specifically shown here, a laminated separator including a polymer compound layer may be used instead of the porous film separator 23.

[0102] Specifically, the laminated separator includes a porous membrane having a pair of surfaces and a polymer compound layer provided on one or both surfaces of the porous membrane. This is because the separator's adhesion to the positive electrode 21 and the negative electrode 22 is improved, thereby suppressing misalignment of the battery element 20, i.e., miswinding of the positive electrode 21, the negative electrode 22, and the separator. This suppresses swelling of the secondary battery even if a decomposition reaction of the electrolyte occurs. The polymer compound layer includes a polymer compound such as polyvinylidene fluoride. This is because polymer compounds such as polyvinylidene fluoride have excellent physical strength and are electrochemically stable.

[0103] One or both of the porous film and the polymer compound layer may contain one or more types of insulating particles. This is because the insulating particles dissipate heat when the secondary battery generates heat, improving the safety (heat resistance) of the secondary battery. The insulating particles include inorganic particles and resin particles. The inorganic particles include one or more types of inorganic materials such as aluminum oxide, aluminum nitride, boehmite, silicon oxide, titanium oxide, magnesium oxide, and zirconium oxide. The resin particles include one or more types of resin materials such as acrylic resin and styrene resin.

[0104] When a laminated separator is produced, a precursor solution containing a polymer compound and an organic solvent is prepared, and then the precursor solution is applied to one or both sides of a porous film. In this case, the precursor solution may contain a plurality of insulating particles.

[0105] Even when this laminated separator is used, the same effect can be obtained because lithium can move in an ionic state between the positive electrode 21 and the negative electrode 22. In this case, as described above, in particular, the displacement of the battery element 20 is suppressed, thereby further suppressing swelling of the secondary battery, thereby achieving a greater effect.

[0106] [Variation 3] An electrolyte solution, which is a liquid electrolyte, was used. However, although not specifically shown here, an electrolyte layer, which is a gel electrolyte, may be used instead of the electrolyte solution.

[0107] In the battery element 20 using the electrolyte layer, the positive electrode 21 and the negative electrode 22 are stacked with the separator 23 and the electrolyte layer interposed therebetween, and the positive electrode 21, the negative electrode 22, the separator 23, and the electrolyte layer are wound together. The electrolyte layer is interposed between the positive electrode 21 and the separator 23, and also between the negative electrode 22 and the separator 23.

[0108] Specifically, the electrolyte layer contains a polymer compound together with an electrolytic solution, and the electrolytic solution is held by the polymer compound. This is because leakage of the electrolytic solution is suppressed. The composition of the electrolytic solution is as described above. The polymer compound contains polyvinylidene fluoride, etc. When forming the electrolyte layer, a precursor solution containing an electrolytic solution, a polymer compound, an organic solvent, etc. is prepared, and then the precursor solution is applied to one or both surfaces of each of the positive electrode 21 and the negative electrode 22.

[0109] Even when this electrolyte layer is used, the same effect can be obtained because lithium can move in an ionic state through the electrolyte layer between the positive electrode 21 and the negative electrode 22. In this case, leakage of the electrolyte solution is particularly suppressed as described above, and therefore a greater effect can be obtained.

[0110] <3. Uses of secondary batteries> Finally, the uses (application examples) of the secondary battery will be described.

[0111] The use of the secondary battery is not particularly limited. The secondary battery used as a power source may be a main power source or an auxiliary power source in electronic devices, electric vehicles, etc. The main power source is a power source that is used preferentially regardless of the presence or absence of other power sources. The auxiliary power source may be a power source used in place of the main power source or a power source that can be switched from the main power source.

[0112] Specific examples of uses for secondary batteries are as follows: Electronic devices such as video cameras, digital still cameras, mobile phones, laptop computers, headphone stereos, portable radios, and portable information terminals; Storage devices such as backup power supplies and memory cards; Power tools such as power drills and power saws; Battery packs installed in electronic devices; Medical electronic devices such as pacemakers and hearing aids; Electric vehicles such as electric cars (including hybrid cars); Power storage systems such as home or industrial battery systems that store power in preparation for emergencies, etc. In these uses, one secondary battery may be used, or multiple secondary batteries may be used.

[0113] The battery pack may include a single cell or a battery pack. The electric vehicle is a vehicle that runs on a secondary battery as a driving power source, and may be a hybrid vehicle that also includes a driving source other than the secondary battery. In a home power storage system, power stored in a secondary battery, which is a power storage source, can be used to power home electrical appliances, etc.

[0114] Here, an example of the use of the secondary battery will be specifically described. The configuration described below is merely an example and can be modified as appropriate.

[0115] Figure 4 shows the block diagram of a battery pack, which is an example of an application of a secondary battery. The battery pack described here is a battery pack (a so-called soft pack) that uses one secondary battery, and is installed in electronic devices such as smartphones.

[0116] 4, the battery pack includes a power supply 51 and a circuit board 52. The circuit board 52 is connected to the power supply 51 and includes a positive terminal 53, a negative terminal 54, and a temperature detection terminal 55.

[0117] The power source 51 includes one secondary battery. In this secondary battery, the positive electrode lead is connected to a positive electrode terminal 53, and the negative electrode lead is connected to a negative electrode terminal 54. The power source 51 is connected to the outside via the positive electrode terminal 53 and the negative electrode terminal 54, and is therefore capable of charging and discharging. The circuit board 52 includes a control unit 56, a switch 57, a thermosensitive resistor element (a so-called PTC element) 58, and a temperature detection unit 59. However, the PTC element 58 may be omitted.

[0118] The control unit 56 includes a central processing unit (CPU) and memory, and controls the operation of the entire battery pack. The control unit 56 detects and controls the usage state of the power source 51.

[0119] When the voltage of power source 51 (secondary battery) reaches the overcharge detection voltage or the overdischarge detection voltage, control unit 56 turns off switch 57 to prevent charging current from flowing through the current path of power source 51. The overcharge detection voltage is not particularly limited, but specifically, it is 4.20V±0.05V, and the overdischarge detection voltage is not particularly limited, but specifically, it is 2.40V±0.10V.

[0120] Switch 57 includes a charge control switch, a discharge control switch, a charging diode, a discharging diode, etc., and switches between the presence and absence of a connection between power supply 51 and an external device in response to an instruction from control unit 56. Switch 57 includes a field effect transistor (MOSFET) using a metal oxide semiconductor, etc., and the charge current and the discharge current are each detected based on the ON resistance of switch 57.

[0121] Temperature detection unit 59 includes a temperature detection element such as a thermistor. Temperature detection unit 59 measures the temperature of power supply 51 using temperature detection terminal 55 and outputs the temperature measurement result to control unit 56. The temperature measurement result measured by temperature detection unit 59 is used when control unit 56 controls charging and discharging in the event of abnormal heat generation, and when control unit 56 performs correction processing when calculating the remaining capacity. [Example]

[0122] An embodiment of the present technology will be described.

[0123] <Experimental Examples 1 and 2 and Comparative Example 1> As will be described below, after the secondary battery was fabricated, the battery characteristics of the secondary battery were evaluated.

[0124] Here, a test secondary battery was fabricated for simple evaluation. Figure 5 shows the cross-sectional structure of the test secondary battery (a coin-type lithium ion secondary battery). In this case, as shown in Figure 3, a positive electrode conductive agent 212 in which a positive electrode active material 211 is inserted into a plurality of pores 212K was used.

[0125] 5, this secondary battery includes a test electrode 61, a counter electrode 62, a separator 63, an outer cup 64, an outer can 65, a gasket 66, and an electrolyte (not shown). Here, the test electrode 61 corresponds to the positive electrode, and the counter electrode 62 corresponds to the negative electrode.

[0126] The test electrode 61 is housed inside an exterior cup 64, and the counter electrode 62 is housed inside an exterior can 65. The test electrode 61 and the counter electrode 62 are stacked together with a separator 63 interposed therebetween, and the test electrode 61, the counter electrode 62, and the separator 63 are each impregnated with an electrolyte. The exterior cup 64 and the exterior can 65 are crimped together with a gasket 66, so that the test electrode 61, the counter electrode 62, and the separator 63 are sealed inside the exterior cup 64 and the exterior can 65.

[0127] (Preparation of test electrode (positive electrode)) First, a container (volume = 500 cm 3 (=500cc)), 5g of powdered positive electrode conductive agent 212 (activated carbon powder) and 200cm of solvent (pure water) were added. 3(=200 cc) and 500 g of zirconia balls (diameter=2 mm) were mixed together to obtain a first mixture. This positive electrode conductive agent 212 has a plurality of pores 212K, as described above.

[0128] Next, the first mixture was stirred in the container using a stirrer (stirrer rotation speed = 150 rpm, stirring time = 16 hours) to disintegrate the positive electrode conductive agent 212, and then the zirconia balls were recovered from the container. In this case, the average particle diameter (volume basis) of the positive electrode conductive agent 212 after disintegration was set to 0.751 μm.

[0129] When measuring the average particle size (volume basis), a laser diffraction / scattering particle size distribution analyzer (particle size distribution) LA-960 manufactured by Horiba, Ltd. was used as the measuring device, and the measurement conditions were as follows: measurement method = volume basis, dispersant = ethanol, dispersion conditions (ultrasonic application intensity and application time) = intensity 5 and application time = 5 minutes.

[0130] The pore characteristics of the positive electrode conductive material 212 (activated carbon) after disintegration are as follows: Specific surface area = 2105 m 2 / g, total pore volume (P / P0 = 0.990) = 1.64 cm 3 / g, micropore volume (P / P0 = 0.2) = 0.89 cm 3 / g. Measurement results using the HK method (micropore analysis (pore diameter = 0 nm to 2 nm)) showed that the micropore volume (Vp) was 0.85 cm 3 / g, pore width peak Wpeak(Vol) = 0.61 nm, average pore width = 0.74 nm, cumulative area = 2318 m 2 / g.

[0131] When evaluating pore characteristics, the evaluation equipment used was a BELSORP specific surface area / pore distribution analyzer manufactured by Microtrac-Bell Corporation, and the evaluation conditions were as follows: heat treatment temperature / time = 150°C / 6 hours (vacuum degassing), adsorption gas = nitrogen gas, measurement temperature = 77.36 K, measurement range = relative pressure (up to 0.200 (P / P0)), BET specific surface area = minimum value selected at a point with good linearity at extremely low relative pressures where the c value does not become negative (in accordance with ISO9277 (JIS Z 8830)), BET method = pore volume calculation relative pressure (P / P0 = 0.200), HK method = calculation range (0.00 nm to 2.00 nm).

[0132] Next, the first mixture after decomposition and powdered cathode active material 211 (sulfur powder) were mixed together to obtain a second mixture. In this case, the mixing ratio (weight ratio) was set to (first mixture after decomposition): (cathode active material 211) = 40:60. Next, the second mixture was heated (heating temperature = 150°C, heating time = 1 hour) in an inert atmosphere (argon gas). As a result, the cathode active material 211 was filled into each of the multiple pores 212K in the cathode conductor 212.

[0133] Next, the positive electrode conductor 212, in which the positive electrode active material 211 was filled in each of the pores 212K, a solvent (pure water), a positive electrode binder (styrene butadiene rubber), an additional positive electrode conductor (acetylene black), and a carbon / nitrogen-containing metal compound were mixed together to prepare a positive electrode mixture slurry. In this case, the mixing ratio was adjusted so that after the formation of the positive electrode active material layer 21B described below (after the positive electrode mixture slurry was dried), the content of the positive electrode active material 211 was 50.5 wt % and the content of the carbon / nitrogen-containing metal compound was 5 wt %. Metal cyanamide (zinc cyanamide) and metal carbodiimide (calcium carbodiimide) were used as the carbon / nitrogen-containing metal compound.

[0134] Next, the cathode mixture slurry was applied to both sides of the cathode current collector 21A (aluminum foil, thickness = 15 μm) using a coating device, and then the cathode mixture slurry was dried (drying temperature = 80 ° C.) to form the cathode active material layer 21B. In this case, the basis weight of the cathode active material (sulfur) was 1.7 mg / cm 2 It was decided.

[0135] Finally, the positive electrode current collector 21A on which the positive electrode active material layer 21B was formed was punched out into a disk shape (diameter=12 mm), thereby completing the test electrode 61.

[0136] For comparison, a test electrode 61 was prepared in the same manner except that no carbon / nitrogen-containing metal compound was used. In this case, the weight of the positive electrode active material (sulfur) was 1.5 mg / cm. 2 It was decided.

[0137] (Preparation of counter electrode (negative electrode)) An alkali metal (lithium metal plate) serving as a negative electrode active material was punched out into a disk shape (diameter = 16 mm), thereby obtaining a counter electrode 62.

[0138] (Preparation of Electrolyte) After adding an electrolyte salt (lithium bis(trifluoromethanesulfonyl)imide) to a solvent (vinylene carbonate, an unsaturated cyclic carbonate, and monofluoroethylene carbonate, a fluorinated cyclic carbonate), the solvent was stirred. In this case, the mixing ratio (volume ratio) of the solvents was vinylene carbonate:monofluoroethylene carbonate = 50:50, and the content of the electrolyte salt relative to the solvent was 1 mol / L (= 1 mol / dm 3 ) Thus, the electrolyte solution was prepared.

[0139] (Secondary battery assembly) First, the test electrode 61 was placed inside the exterior cup 64, and the counter electrode 62 was placed inside the exterior can 65. Next, the test electrode 61 placed inside the exterior cup 64 and the counter electrode 62 placed inside the exterior can 65 were stacked together with an electrolyte-impregnated separator 63 (Celgard 3501, a dry separator manufactured by Celgard Co., Ltd.) interposed therebetween. Finally, with the test electrode 61 and the counter electrode 62 stacked together with the separator 63 interposed therebetween, the exterior cup 64 and the exterior can 65 were crimped together with a gasket 66. As a result, the test electrode 61 and the counter electrode 62 were sealed inside the exterior cup 64 and the exterior can 65, and a secondary battery was assembled.

[0140] (Stabilization of secondary batteries) The secondary battery was charged and discharged three times in a room temperature environment (temperature = 25°C). In this case, during discharge, it was discharged at a constant current of 0.05 C until the voltage reached 1.0 V, and during charge, it was charged at a constant current of 0.05 C until the voltage reached 3.0 V. Note that 0.05 C is the current value that fully discharges the battery capacity (theoretical capacity) in 20 hours.

[0141] As a result, the test electrode 61 and the counter electrode 62 were electrochemically stabilized, and the secondary battery was completed.

[0142] [Evaluation of battery characteristics] The battery characteristics, ie, charge / discharge characteristics and cycle characteristics, were evaluated, and the results shown in Table 1 were obtained.

[0143] (Charge / discharge characteristics) The secondary battery was charged and discharged 30 times in a room temperature environment (temperature = 25°C), and the discharge capacity at the 30th cycle was measured, as well as the charge capacity at the 30th cycle. The charge and discharge conditions were the same as those used for stabilizing the secondary battery, except that the discharge current was changed to 0.2 C and the charge current was changed to 0.2 C. 0.2 C is the current value that fully discharges the battery capacity in 5 hours.

[0144] From this, the coulombic efficiency, which is an index for evaluating the charge / discharge characteristics, was calculated based on the formula: coulombic efficiency (%)=(charge capacity at 30th cycle / discharge capacity at 30th cycle)×100.

[0145] (Cycle characteristics) First, the discharge capacity (discharge capacity at the first cycle) was measured by charging and discharging the secondary battery in a room temperature environment (temperature = 25°C). Next, the discharge capacity (discharge capacity at the 30th cycle) was measured by repeatedly charging and discharging the secondary battery in the same environment until the number of cycles reached 30. The charge and discharge conditions were the same as those used to evaluate the charge and discharge characteristics.

[0146] From this, the capacity retention rate, which is an index for evaluating cycle characteristics, was calculated based on the formula: capacity retention rate (%)=(discharge capacity at 30th cycle / discharge capacity at 1st cycle)×100.

[0147] [Table 1]

[0148] [Consideration] As shown in Table 1, the coulombic efficiency and the cycle retention rate each varied greatly depending on the configuration of the positive electrode 21.

[0149] Specifically, when the positive electrode active material layer 21B contained a carbon / nitrogen-containing metal compound (Examples 1 and 2), the Coulomb efficiency and the capacity retention rate increased compared to when the positive electrode active material layer 21B did not contain a carbon / nitrogen-containing metal compound (Comparative Example 1).

[0150] In particular, when the positive electrode active material layer 21B contains a carbon / nitrogen-containing metal compound, the following trends were observed. First, whether a metal cyanamide or a metal carbodiimide was used as the carbon / nitrogen-containing metal compound, high Coulombic efficiency and a high capacity retention rate were obtained. Second, when the positive electrode active material layer 21B contains a positive electrode conductor 212 having a plurality of pores 212K and the positive electrode active material 211 is inserted into the plurality of pores 212K, high Coulombic efficiency and a high capacity retention rate were obtained.

[0151] [summary] The results shown in Table 1 indicate that when the positive electrode 21 contains a positive electrode active material and a carbon-nitrogen-containing metal compound, the positive electrode active material contains sulfur, and the carbon-nitrogen-containing metal compound contains carbon, nitrogen, and a metal element as constituent elements, the charge-discharge characteristics and cycle characteristics are both improved. Therefore, excellent battery characteristics can be obtained in the secondary battery.

[0152] The present technology has been described above with reference to an embodiment and examples. However, the configuration of the present technology is not limited to the configuration described in the embodiment and examples, and can be modified in various ways.

[0153] Specifically, the battery structure of the secondary battery has been described as being of a laminate film type and a coin type. However, the battery structure of the secondary battery is not particularly limited, and may be of a cylindrical type, a square type, a button type, or the like.

[0154] The battery element has been described as having a wound structure. However, the structure of the battery element is not particularly limited, and may be a stacked structure or a zigzag structure. In the stacked structure, the positive and negative electrodes are stacked on top of each other, and in the zigzag structure, the positive and negative electrodes are folded in a zigzag pattern.

[0155] Furthermore, although the electrode reactant is lithium in the above description, the electrode reactant is not particularly limited. Specifically, as described above, the electrode reactant may be other alkali metals such as sodium and potassium, or alkaline earth metals such as beryllium, magnesium, and calcium. In addition, the electrode reactant may be other light metals such as aluminum.

[0156] The effects described in this specification are merely examples, and the effects of the present technology are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present technology.

[0157] The present technology can also be configured as follows. <1> a positive electrode, a negative electrode, and an electrolyte; the positive electrode includes a positive electrode active material and a carbon-nitrogen-containing metal compound; the positive electrode active material contains sulfur, The carbon-nitrogen-containing metal compound contains carbon, nitrogen, and a metal element as constituent elements. Secondary battery. <2> The carbon / nitrogen-containing metal compound includes at least one of a metal cyanamide and a metal carbodiimide. <1> The secondary battery according to claim 1. <3> The metal element includes at least one of zinc and calcium. <2> The secondary battery according to claim 1. <4> the negative electrode includes a negative electrode active material, The negative electrode active material contains an alkali metal. <1> Or <3> 10. The secondary battery according to claim 9, wherein the second battery is a battery having a capacitance of 100.degree. <5> The alkali metal includes lithium. <4> The secondary battery according to claim 1. <6> The positive electrode further includes a positive electrode conductive agent, The positive electrode conductive agent contains a carbon material. <1> Or <5> 10. The secondary battery according to claim 9, wherein the second battery is a battery having a capacitance of 100.degree. <7> The positive electrode conductive agent has a plurality of pores, The positive electrode active material is inserted into the plurality of pores. <6> The secondary battery according to claim 1. <8> It is a lithium-sulfur secondary battery. <1> Or <7> 10. The secondary battery according to claim 9, wherein the second battery is a battery having a capacitance of 100.degree. <9> a positive electrode active material and a carbon-nitrogen-containing metal compound, the positive electrode active material contains sulfur, The carbon-nitrogen-containing metal compound contains carbon, nitrogen, and a metal element as constituent elements. Electrodes for secondary batteries.

Claims

1. a positive electrode, a negative electrode, and an electrolyte; the positive electrode includes a positive electrode active material and a carbon-nitrogen-containing metal compound; the positive electrode active material contains elemental sulfur, The carbon / nitrogen-containing metal compound includes at least one of a metal cyanamide and a metal carbodiimide. Secondary battery.

2. The metal element includes at least one of zinc and calcium. The secondary battery according to claim 1 .

3. the negative electrode includes a negative electrode active material, The negative electrode active material contains an alkali metal. The secondary battery according to claim 1 or 2.

4. The alkali metal includes lithium. The secondary battery according to claim 3 .

5. The positive electrode further includes a positive electrode conductive agent, The positive electrode conductive agent contains a carbon material. The secondary battery according to claim 1 or 2.

6. The positive electrode conductive agent has a plurality of pores, The positive electrode active material is inserted into the plurality of pores. The secondary battery according to claim 5 .

7. It is a lithium-sulfur secondary battery. The secondary battery according to claim 1 or 2.

8. a positive electrode active material and a carbon-nitrogen-containing metal compound, the positive electrode active material contains elemental sulfur, The carbon / nitrogen-containing metal compound contains at least one of a metal cyanamide and a metal carbodiimide as a constituent element. Electrodes for secondary batteries.

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