Composite positive electrode active material particles for lithium ion battery, positive electrode active material layer, lithium ion battery, and method for producing composite positive electrode active material particles for lithium ion battery

Abstract

The invention relates to a composite positive electrode active material particle for a lithium ion battery, a positive electrode active material layer, a lithium ion battery, and a method for manufacturing the composite positive electrode active material particle for the lithium ion battery. This composite positive electrode active material particle for a lithium ion battery contains a positive electrode active material, and lithium alloy particles having a lithium alloying potential of 0.5 V (vsLi / Li +) or more and / or metal particles resulting from the detachment of lithium from the lithium alloy, the lithium alloy particles or the metal particles being dispersed in the positive electrode active material.

Description

Technical Field

[0001] The present disclosure relates to composite positive electrode active material particles for lithium ion batteries, positive electrode active material layers, lithium ion batteries, and methods for producing composite positive electrode active material particles for lithium ion batteries. Background Art

[0002] Conventionally, in lithium-ion batteries, improvements have been made to active materials in order to increase capacity.

[0003] Japanese Patent Application Laid-Open No. 2014-010991 discloses an electrode for a non-aqueous electrolyte secondary battery. The specific surface area of ​​the negative electrode active material of the electrode measured by the N2 adsorption method is 3.3 m 2 / g or more and 4.4m 2 / g or less. The DBP oil absorption of the positive electrode active material of the electrode is 30 ml / 100 g or more and 47 ml / 100 g or less. The positive electrode density is 1.8 g / cm 3 Above and 2.2g / cm 3 Japanese Patent Application Laid-Open No. 2014-010991 discloses that the capacity of a negative electrode can be increased by using a lithium (Li) alloy as an active material.

[0004] In addition, nickel-cobalt-manganese (NCM) lithium oxide is widely used as a positive electrode active material, and improvements in its composition are also being studied. Summary of the invention

[0005] When using conventional electrodes such as the electrode of Japanese Patent Application Laid-Open No. 2014-010991, a significant decrease in capacity is sometimes found after initial charging. In addition, the battery also needs to have good cycle characteristics, that is, to suppress the decrease in capacity when repeatedly charging and discharging.

[0006] Therefore, the present disclosure provides a composite positive electrode active material particle for a lithium ion battery that can suppress a decrease in capacity after initial charge and suppress a decrease in capacity when repeated charge and discharge are performed.

[0007] The present inventors have conducted intensive research and have found that the above-mentioned problems can be solved by adopting the following means, thereby completing the present disclosure. That is, the present disclosure is as follows:

[0008] Solution 1

[0009] Composite positive electrode active material particles for lithium ion batteries, comprising: a positive electrode active material, and a lithium alloying potential of 0.5 V (vsLi / Li + ) or more lithium alloy particles and / or metal particles generated by the separation of lithium from the lithium alloy particles, and the lithium alloy particles or the metal particles are dispersed in the positive electrode active material.

[0010] Solution 2

[0011] The composite positive electrode active material particle for lithium ion battery according to embodiment 1, wherein the lithium alloy particle is selected from Li3Bi, Li3Sb, and LiSn.

[0012] Solution 3

[0013] The composite positive electrode active material particle for lithium ion battery according to embodiment 1 or 2, wherein the positive electrode active material is NCM lithium oxide.

[0014] Solution 4

[0015] A positive electrode active material layer comprising the composite positive electrode active material particles for a lithium ion battery according to any one of aspects 1 to 3.

[0016] Solution 5

[0017] A lithium-ion battery comprising the positive electrode active material layer described in Scheme 4.

[0018] Solution 6

[0019] A method for manufacturing a lithium-ion battery, comprising:

[0020] A composite positive electrode active material particle precursor for a lithium ion battery is prepared, wherein the composite positive electrode active material particle precursor for a lithium ion battery contains a positive electrode active material and lithium dispersed in the positive electrode active material with an alloying potential of 0.5 V (vsLi / Li + ) or more lithium alloy particles;

[0021] preparing a positive electrode precursor layer containing at least the composite positive electrode active material particle precursor for lithium ion batteries;

[0022] Obtaining a lithium ion battery precursor which sequentially has the positive electrode precursor layer, the separator or the solid electrolyte layer, and the negative electrode active material layer and is impregnated with an electrolyte; and

[0023] The lithium ion battery precursor is initially charged so that the positive electrode precursor layer becomes a positive electrode active material layer.

[0024] According to the present disclosure, it is possible to provide composite positive electrode active material particles for lithium ion batteries that can suppress a decrease in capacity after initial charge and can suppress a decrease in capacity when repeated charge and discharge are performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention are described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0026] Figure 1A schematic diagram of the composite positive electrode active material particle for lithium ion battery disclosed in the present invention;

[0027] Figure 2 is a schematic diagram of the lithium-ion battery of the present disclosure. DETAILED DESCRIPTION

[0028] Composite positive electrode active material particles for lithium-ion batteries

[0029] like Figure 1 As shown, the composite positive electrode active material particle 112 for lithium ion battery of the present disclosure contains: a positive electrode active material 1122 and a lithium alloying potential of 0.5 V (vsLi / Li + ) or more lithium alloy particles 1124, and / or metal particles 1126 generated by the separation of lithium from the lithium alloy, the lithium alloy particles 1124 or the metal particles 1126 are dispersed in the positive electrode active material 1122.

[0030] The present inventors have found that the reason for the reduction in battery capacity described in Japanese Patent Application Laid-Open No. 2014-010991 is that lithium supplied in the initial positive electrode active material is consumed due to the formation of SEI (Solid Electrolyte Interphase) at the negative electrode during initial charge.

[0031] In this regard, the present inventors have discovered that the capacity of a lithium-ion battery can be improved by using the above-mentioned composite positive electrode active material particles for lithium-ion batteries in the positive electrode precursor layer. Without wishing to be bound by theory, the present inventors believe that the reasons for the improved capacity are as follows. During the initial charge, the lithium of the lithium alloy in the positive electrode precursor layer is released and becomes lithium consumed by the formation of SEI at the negative electrode, which can inhibit the lithium in the positive electrode active material from being consumed by the formation of SEI. In addition, it is believed that the lithium alloying potential of the lithium alloy is 0.5V (vsLi / Li + ) or more, it is possible to suppress the electrochemical reaction inside the positive electrode precursor before the initial charge.

[0032] On the other hand, when lithium alloy particles are used directly, there is a problem of poor cycle characteristics. When repeated charge and discharge are performed, sometimes the capacity decreases significantly with a small number of charge and discharge times. The inventors have found that the reason is that the metal constituting the lithium alloy particles undergoes oxidation dissolution during charging and locally becomes a high-concentration metal ion, which is concentratedly precipitated in one place in the negative electrode and becomes a resistor.

[0033] In this regard, the inventors have found that by dispersing lithium alloy particles in the positive electrode active material, the concentrated precipitation of metals in the negative electrode can be suppressed, thereby solving the above-mentioned problem. Without wishing to be bound by theory, the inventors believe that the reasons for suppressing the concentrated precipitation of metals in the negative electrode are as follows. For the composite positive electrode active material particles for lithium ion batteries disclosed in the present invention, lithium moves to the negative electrode through the active material during charging, and on the other hand, the metal particles generated by the detachment of lithium remain in the active material, thereby suppressing the concentrated precipitation of metals in the negative electrode.

[0034] That is, in the metal particles of the composite positive electrode active material particles for lithium ion batteries disclosed herein, lithium in lithium alloy particles dispersed in the positive electrode active material is separated from the lithium alloy particles during initial charge, so that at least a portion of the lithium alloy particles becomes metal particles.

[0035] Each constituent element of the present disclosure will be described below.

[0036] Positive active material

[0037] As the positive electrode active material, any positive electrode active material can be used without particular limitation, and for example, an oxide containing lithium can be used.

[0038] The lithium-containing oxide used as the positive electrode active material is not particularly limited, and may contain, for example, at least Li, at least one transition metal element selected from Co, Ni and Mn, and O. As such lithium-containing oxides, for example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), and nickel-cobalt-manganese (NCM) lithium oxides in which some elements of these compounds are replaced with other elements can be used. NCM lithium oxides are generally composed of Li a Mn x Ni y Co z O 2±δ (0<a≤1.5, 0≤x≤1.5, 0≤y≤1.5, 0≤z≤1.5, 0<δ(=x+y+z)<1.5) is represented by the general formula. For example, LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), etc. The lithium-containing oxide as the positive electrode active material may have, for example, an O2 type structure, an O3 type structure, or a crystal structure other than these. As the positive electrode active material, only one type may be used alone, or two or more types may be used in combination.

[0039] Lithium alloy particles

[0040] The lithium alloy particles have a lithium alloying potential of 0.5 V (vsLi / Li + ) or more lithium alloy particles.

[0041] The lithium alloying potential of the lithium alloy particles can be 0.6V (vsLi / Li + ) or above, 0.7V(vsLi / Li + ) or above, or 0.8V(vsLi / Li + ) or more, and can be 1.5V (vsLi / Li + ) or less, 1.4V(vsLi / Li + ) or less, 1.3V(vsLi / Li + ) or less, 1.2V(vsLi / Li + ) or less, 1.1V(vsLi / Li + ) or less, 1.0V(vsLi / Li + )the following.

[0042] Among them, the lithium alloying potential (vsLi / Li + ) is the electrode potential of the electrode reaction of formula (1), which is expressed based on the electrode potential of lithium of the following formula (2):

[0043] x + +M+xe - ←→Li x M (1)

[0044] Li + +e - ←→Li (2)

[0045] The lithium alloying potential (vsLi / Li + ) can be measured as the single electrode potential obtained when the alloy is immersed in a lithium salt solution.

[0046] As such lithium alloy particles, for example, Li 3 Bi, Li 3 Sb, LiSn, etc. can be used.

[0047] Metal particles

[0048] The metal particles of the composite positive electrode active material particles for lithium ion batteries disclosed in the present invention are metal particles generated by the desorption of lithium from the above-mentioned lithium alloy particles.

[0049] As such metal particles, for example, bismuth particles, antimony particles, tin particles, etc. can be used.

[0050] Positive electrode active material layer

[0051] The positive electrode active material layer contains the composite positive electrode active material particles for lithium ion batteries. In addition, the positive electrode active material layer may contain any other substances. Examples of other substances include conductive additives and binders.

[0052] Conductive additives

[0053] As the conductive aid optionally contained in the positive electrode precursor layer, a conductive aid known as a conductive aid used in a lithium ion battery can be used. Specifically, carbon materials such as Ketjen black (KB), vapor-grown carbon fiber (VGCF), acetylene black (AB), carbon nanotubes (CNT), carbon nanofibers (CNF), carbon black, coke, graphite, etc. can be used. Alternatively, a metal material that can withstand the environment in which the battery is used can also be used. As a conductive aid, only one can be used alone, or a combination of two or more can be used. The shape of the conductive aid can be various shapes such as powdery and fibrous. There is no particular limitation on the amount of the conductive aid contained in the positive electrode active material layer.

[0054] Adhesives

[0055] As the binder optionally contained in the positive electrode precursor layer, a binder known as a binder used in a lithium ion battery can be used. For example, styrene butadiene rubber (SBR) based binders, carboxymethyl cellulose (CMC) based binders, acrylonitrile butadiene rubber (ABR) based binders, butadiene rubber (BR) based binders, polyvinylidene fluoride (PVDF) based binders, polytetrafluoroethylene (PTFE) based binders, etc. can be used. The binder can be used alone or in combination of two or more. The amount of the binder contained in the positive electrode active material layer is not particularly limited.

[0056] Lithium-ion battery

[0057] The lithium ion battery of the present disclosure has the above-mentioned positive electrode active material layer, a separator or a solid electrolyte layer, and a negative electrode active material layer.

[0058] Figure 1 The structure of a lithium ion battery 100 according to one embodiment of the present disclosure is schematically shown. Figure 1 As shown, the lithium ion battery 100 may include a positive electrode 10, a separator 20, and a negative electrode 30. In addition, the positive electrode 10 may include a positive electrode active material layer 11 and a positive electrode collector layer 12, and the negative electrode 30 may include a negative electrode active material layer 31 and a negative electrode collector layer 32. In this case, the positive electrode active material layer 11 may include the above-mentioned positive electrode active material. In addition, although not shown, the positive electrode active material layer 11 and the negative electrode active material layer 31 may include an electrolyte.

[0059] In addition, when the lithium ion battery of the present disclosure is a solid battery, the lithium ion battery of the present disclosure may include a solid electrolyte layer present at the position of the separator 20 instead of the separator 20 .

[0060] Hereinafter, each component of the lithium ion battery of the present disclosure will be described.

[0061] Positive electrode collector layer

[0062] The positive electrode collector layer can be composed of known metals that can be used as positive electrode collectors of lithium ion batteries. As such metals, metal materials containing at least one element selected from Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Pb, Co, Cr, Zn, Ge, In, Sn, and Zr can be exemplified. There is no particular limitation on the form of the positive electrode collector. Various forms such as foil, mesh, and porous can be used. It can also be a product obtained by evaporating and plating the above metal on the surface of the substrate.

[0063] Separator

[0064] As the separator, a separator known as a separator used in a lithium ion battery can be used. For example, the separator can be composed of resins such as polyethylene (PE), polypropylene (PP), polyester and polyamide. The separator can be a single-layer structure, or it can be a multi-layer structure. As a separator of a multi-layer structure, for example, a separator of a multi-layer structure composed of the above-mentioned resins can be used, such as a separator of a 2-layer structure of PE / PP, or a separator of a 3-layer structure of PP / PE / PP or PE / PP / PE. The separator can be composed of non-woven fabrics such as cellulose non-woven fabrics, resin non-woven fabrics, and glass fiber non-woven fabrics. There is no particular limitation on the thickness of the separator, for example, it can be greater than 5μm and less than 1mm.

[0065] Negative electrode active material layer

[0066] The negative electrode active material layer contains the negative electrode active material. In addition, the negative electrode active material layer may contain any other components. As other components, for example, a conductive aid and a binder can be listed. As the conductive aid and the binder, the description of the positive electrode active material layer can be referred to.

[0067] Negative electrode active material layer: Negative electrode active material

[0068] As the negative electrode active material, various materials whose potential for absorbing and releasing ions (charge and discharge potential) is lower than that of the above-mentioned positive electrode active materials can be used. As the negative electrode active material, for example, silicon-based active materials such as Si, Si alloys, and silicon oxide; carbon-based active materials such as graphite, graphite, and hard carbon; various oxide-based active materials such as lithium titanate; metallic lithium, lithium alloys, etc. can be used. The negative electrode active material can be used alone or in combination of two or more.

[0069] Negative electrode collector layer

[0070] The negative electrode collector layer can be composed of known metals that can be used as negative electrode collectors of lithium ion batteries. As such a metal, for example, it can be a metal material containing at least one element selected from Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Pb, Co, Cr, Zn, Ge, In, Sn, and Zr. The form of the negative electrode collector layer is not particularly limited, and it can be various forms such as foil, mesh, and porous. The negative electrode collector layer can be a product of plating or vapor-depositing the above metal on the surface of a substrate composed of any material. In addition, the surface of the negative electrode collector layer can be coated with a carbon material or the like.

[0071] Non-aqueous electrolytes

[0072] The non-aqueous electrolyte may contain a non-aqueous solvent and an electrolyte. The electrolyte may contain alkali metal ions, such as lithium ions, as carrier ions.

[0073] As for the non-aqueous solvent, a solvent other than water, such as an organic solvent, can be used. As the organic solvent, for example, carbonate-based solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) can be used. These organic solvents can be used alone or in combination.

[0074] The electrolyte is not particularly limited, and may be, for example, a lithium salt. As the lithium salt, for example, LiPF6 can be used.

[0075] Solid electrolyte layer

[0076] The solid electrolyte layer may contain a solid electrolyte.

[0077] The material of the solid electrolyte is not particularly limited, and any material that can be used as a solid electrolyte for lithium-ion batteries can be used. For example, the solid electrolyte may be a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer electrolyte, but is not limited thereto. In addition, these solid electrolytes may be used alone or in combination of two or more.

[0078] As the sulfide solid electrolyte, any sulfide solid electrolyte can be used. Specifically, as the sulfide solid electrolyte, for example, Li2S-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Si2S-P2S5, Li2S-P2S5-LiI-LiBr, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5-GeS2 and the like can be exemplified.

[0079] Examples of oxide solid electrolytes include Li7La3Zr2O 12、Li 7-x Ln3Z 1-x Nb x O 12、 Li 7- 3x La3Zr2Al x O 12 , Li 3x La 2 / 3-x TiO3、Li 1+x Al x Ti 2-x (PO4)3、Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, or Li 3+x PO 4- x N x (LiPON) etc., but are not limited to these. These may be amorphous or crystalline.

[0080] Examples of the polymer electrolyte include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof, but the polymer electrolyte is not limited thereto.

[0081] Method for manufacturing lithium-ion battery

[0082] The disclosed method for obtaining a lithium-ion battery comprises:

[0083] A composite positive electrode active material particle precursor for a lithium ion battery is prepared, wherein the composite positive electrode active material particle precursor for a lithium ion battery contains a positive electrode active material and lithium dispersed in the positive electrode active material with an alloying potential of 0.5 V (vsLi / Li + ) or more lithium alloy particles;

[0084] preparing a positive electrode precursor layer containing at least the composite positive electrode active material particle precursor for lithium ion batteries;

[0085] Obtaining a lithium ion battery precursor which sequentially has the positive electrode precursor layer, the separator or the solid electrolyte layer, and the negative electrode active material layer and is impregnated with an electrolyte; and

[0086] The lithium ion battery precursor is initially charged so that the positive electrode precursor layer becomes a positive electrode active material layer.

[0087] Each step of the method of the present disclosure will be described below.

[0088] Preparation of composite positive electrode active material particle precursor for lithium-ion batteries

[0089] The composite positive electrode active material particle precursor for lithium ion battery contains a positive electrode active material and / or lithium dispersed in the positive electrode active material with an alloying potential of 0.5 V (vsLi / Li + ) or more lithium alloy particles.

[0090] Regarding the preparation of the composite positive electrode active material particle precursor for lithium ion batteries, in one embodiment, it can be carried out by a method comprising the following steps:

[0091] crushing lithium alloy particles in an inactive environment;

[0092] Dispersing lithium alloy particles in molten positive electrode active material, and then cooling and solidifying the material to prepare a precursor block; and

[0093] The cooled precursor agglomerates are pulverized to obtain composite positive electrode active material particle precursors for lithium ion batteries.

[0094] Regarding the preparation of the composite positive electrode active material particle precursor for lithium ion batteries, in another embodiment, it can be carried out by a method comprising the following steps:

[0095] crushing lithium alloy particles in an inactive environment;

[0096] Dispersing lithium alloy particles in a molten material for obtaining a positive electrode active material, and then cooling and solidifying the material to prepare a precursor agglomerate; and

[0097] pulverizing the cooled precursor agglomerate to obtain particles in which lithium alloy particles are dispersed in a material;

[0098] The particles are mixed with other materials for obtaining a positive electrode active material, and then reacted to obtain a composite positive electrode active material particle precursor for a lithium ion battery.

[0099] As a material for obtaining the positive electrode active material, for example, a hydroxide, an oxide, a carbonate, or the like of a metal constituting the positive electrode active material can be used.

[0100] Fabrication of cathode precursor layer

[0101] The positive electrode precursor layer contains at least a composite positive electrode active material particle precursor for lithium ion batteries. In addition, the positive electrode precursor layer may contain any other substances. Examples of other substances include conductive additives and binders.

[0102] The positive electrode precursor layer can be produced by mixing the respective materials constituting the positive electrode precursor layer and then applying the mixture.

[0103] Preparation of Li-ion Battery Precursors

[0104] The lithium ion battery precursor has a positive electrode precursor layer, a separator or a solid electrolyte layer, and a negative electrode active material layer in this order, and is impregnated (immersed) with a non-aqueous electrolyte. The lithium ion battery precursor can be prepared by a known method.

[0105] In addition, the lithium ion battery precursor may further include a positive electrode current collector layer and a negative electrode current collector layer.

[0106] For each component of the lithium ion battery precursor, reference can be made to the description of the lithium ion battery.

[0107] Preparation of positive electrode active material layer

[0108] The positive electrode active material layer is prepared by initially charging the lithium ion battery precursor so that the positive electrode precursor layer becomes the positive electrode active material layer. As a result, at least a portion of the lithium of the lithium alloy particles in the composite positive electrode active material particle precursor for lithium ion batteries is separated to generate metal particles. As a result, the composite positive electrode active material particle precursor for lithium ion batteries becomes a composite positive electrode active material particle for lithium ion batteries in which lithium alloy particles or metal particles are dispersed in the composite positive electrode active material particles for lithium ion batteries, that is, the positive electrode active material.

[0109] By initially charging the lithium ion battery precursor having the positive electrode precursor layer, the lithium in the lithium alloy particles is consumed by SEI formation at the negative electrode. As a result, when the lithium alloy particles contain at least one of Li3Bi and Li3Sb, the obtained positive electrode active material layer contains at least one of bismuth single substance particles and antimony single substance particles.

[0110] The conditions for initial charging may be known conditions.

[0111] The present disclosure will be described more specifically using Examples and Comparative Examples, but the present disclosure is not limited to these Examples and Comparative Examples.

[0112] Lithium-ion battery manufacturing

[0113] Example 1

[0114] First, a 92.3 mg LiNi 0.8 Co 0.1 Mn 0.1 A composite positive electrode active material particle precursor for a lithium ion battery comprising O2 (NCM811) and 8.4 mg of Li3Bi powder as lithium alloy particles.

[0115] Specifically, in an inactive environment, Li3Bi powder as lithium alloy particles is crushed. Secondly, nickel hydroxide Ni(OH)2 as a positive electrode active material is melted at 230°C, crushed Li3Bi powder is added thereto and dispersed, cooled and solidified to obtain a precursor agglomerate. Secondly, the precursor agglomerate is crushed, manganese compound, cobalt compound and lithium source are mixed therein, and sintered at 850°C for 15 hours in an oxygen atmosphere to obtain a composite positive electrode active material particle precursor for a lithium ion battery. Here, by superimposing the SEM (scanning electron microscope) image with the EDS mapping of nickel (Ni) and bismuth (Bi), it is confirmed that in the obtained composite positive electrode active material particle precursor, the lithium alloy particles are dispersed in the positive electrode active material. That is, it is confirmed that the lithium alloy particles are contained in the positive electrode active material.

[0116] The active material particle precursor, conductive additive, and binder described above were mixed in NMP to prepare a slurry, which was applied to an Al foil serving as a positive electrode current collector layer and dried to obtain a positive electrode precursor layer.

[0117] The obtained positive electrode precursor layer was placed opposite to a negative electrode active material layer containing graphite as an active material via a separator, and vacuum dried. Thereafter, a non-aqueous electrolyte was added to obtain a lithium ion battery precursor.

[0118] Example 2-3

[0119] The lithium ion battery precursor of Example 2-3 was obtained in the same manner as in Example 1 except that the content of the positive electrode active material and the type and content of the lithium alloy particles were changed as shown in Table 1.

[0120] Reference Example 1-3

[0121] Lithium ion battery precursors of Reference Examples 1-3 were obtained in the same manner as in Example 1-3 except that the same amounts of positive electrode active material particles and lithium alloy particles were used instead of the active material particle precursor.

[0122] evaluate

[0123] Battery capacity during initial charge and discharge

[0124] Based on the mass of the positive electrode active material contained in the battery cell, the current value of 210 mA / g was defined as 1C rate, 0.2C was used as the charge and discharge current value, and 0.03C was used as the termination current value, and CCCV charging and CCCV discharging were performed. The upper limit voltage during charging was set to 4.25 V, and the lower limit voltage during discharging was set to 2.50 V. The obtained CCCV discharge capacity was used as the capacity of the battery cell and set as the evaluation index of the present disclosure.

[0125] Cycle characteristics

[0126] After measuring the capacity of the battery cell, a cycle test (CC charge and CC discharge, upper and lower voltage limits 3-4.25V, 0.3C rate) was carried out to determine the number of cycles until the CC discharge capacity became 40% or less of the initial discharge capacity.

[0127] Table 1 shows the configurations and evaluation results of Examples and Comparative Examples.

[0128]

[0129] Table 1 shows the following: a lithium ion battery using composite positive electrode active material particles for lithium ion batteries in which lithium alloy particles or metal particles are dispersed in a positive electrode active material can suppress a decrease in capacity after initial charge and a decrease in capacity during repeated charge and discharge.

Claims

1. A composite positive electrode active material particle for a lithium ion battery, comprising: Positive electrode active material, and Lithium alloying potential is 0.5V (vsLi / Li + ) or more lithium alloy particles and / or metal particles generated by the separation of lithium from the lithium alloy particles, The lithium alloy particles or the metal particles are dispersed in the positive electrode active material.

2. The composite positive electrode active material particle for lithium ion battery according to claim 1, wherein The lithium alloy particles are selected from Li3Bi, Li3Sb and LiSn.

3. The composite positive electrode active material particle for lithium ion battery according to claim 1 or 2, wherein: The positive electrode active material is NCM lithium oxide. 4 . A positive electrode active material layer comprising the composite positive electrode active material particles for lithium ion batteries according to claim 1 . 5 . A lithium ion battery comprising the positive electrode active material layer according to claim 4 .

6. A method for manufacturing a lithium-ion battery, comprising: A composite positive electrode active material particle precursor for a lithium ion battery is prepared, wherein the composite positive electrode active material particle precursor for a lithium ion battery contains a positive electrode active material and lithium dispersed in the positive electrode active material with an alloying potential of 0.5 V (vsLi / Li + ) or more lithium alloy particles; preparing a positive electrode precursor layer containing at least the composite positive electrode active material particle precursor for lithium ion batteries; Obtaining a lithium ion battery precursor which sequentially has the positive electrode precursor layer, the separator or the solid electrolyte layer, and the negative electrode active material layer and is impregnated with an electrolyte; and The lithium ion battery precursor is initially charged so that the positive electrode precursor layer becomes a positive electrode active material layer.

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