WO2014013837A1 - Active material particles for lithium ion secondary batteries, and lithium ion secondary battery using same - Google Patents

Active material particles for lithium ion secondary batteries, and lithium ion secondary battery using same Download PDF

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WO2014013837A1
WO2014013837A1 PCT/JP2013/067027 JP2013067027W WO2014013837A1 WO 2014013837 A1 WO2014013837 A1 WO 2014013837A1 JP 2013067027 W JP2013067027 W JP 2013067027W WO 2014013837 A1 WO2014013837 A1 WO 2014013837A1
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lithium ion
active material
ion secondary
electrode active
secondary batteries
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PCT/JP2013/067027
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French (fr)
Japanese (ja)
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良幸 高森
心 ▲高▼橋
正 藤枝
拓也 青柳
尚貴 木村
達哉 遠山
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株式会社 日立製作所
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a lithium ion secondary battery active material particle and a lithium ion secondary battery using the same.
  • a lithium ion secondary battery has a high atomic energy density and a high gravimetric energy density compared to other secondary batteries because of its low atomic weight and high ionization tendency. Therefore, it is widely used as a power source for portable devices such as mobile phones and notebook PCs. Furthermore, because of global warming prevention and fossil fuel exhaustion problems, application to power sources for power storage of power generation systems using renewable energy such as solar power generation and solar power generation and solar power generation is also promoted. ing. Most of lithium ion secondary batteries put to practical use at present use a flammable organic electrolyte solution as the electrolyte. Therefore, there is a risk such as liquid leakage and ignition, and the development of a highly safe lithium ion secondary battery free of these risks is desired.
  • Patent Document 1 a change in battery dimensions, an increase in internal resistance, and a charge / discharge performance at a large current due to expansion / contraction of an active material accompanying charge / discharge of a lithium secondary battery. It has been proposed to solve the deterioration of the above using active material particles coated with a covering layer containing a conductive agent and a lithium ion conductive inorganic solid electrolyte.
  • the surface of the active material of the all solid lithium ion secondary battery is covered with a layer mainly composed of a hard glassy solid electrolyte having lithium ion conductivity, so that it is active when lithium ions are inserted into the active material.
  • the expansion of the substance can be suppressed by the hard coating layer covering the active material.
  • the lithium ion secondary battery of the present invention for solving the above problems includes a positive electrode, a negative electrode, and a solid electrolyte, and at least one of a positive electrode active material and a negative electrode active material occludes and releases lithium ions to expand. It is characterized in that it is coated with a coating layer containing oxide glass having a shrinking property.
  • the positive electrode active material particles or the negative electrode active material particles according to the present invention for solving the above problems are a coating layer including an oxide glass having a property of absorbing and releasing lithium ions to expand and contract the surface of the active material. It is characterized by being covered.
  • the coating layer is preferably a low melting point oxide glass having lithium ion conductivity and containing vanadium and / or phosphorus or tellurium.
  • the above configuration it is possible to provide a highly safe and long life all solid lithium ion secondary battery.
  • the expansion and contraction of the positive and negative electrode active materials accompanying charge and discharge the contact surfaces of the positive and negative electrode active materials and the solid electrolyte are peeled off to prevent the lithium ion conductive network from being divided.
  • the lithium ion conductivity of the lithium ion secondary battery can be maintained, and the performance deterioration due to the repetition of charge and discharge cycles can be suppressed.
  • FIG. 2 is a schematic view of an all solid lithium ion secondary battery.
  • the solid electrolyte layer 4 is disposed between the positive electrode 5 and the negative electrode 7.
  • the all solid lithium ion secondary battery is highly safe because it uses a nonflammable solid electrolyte having lithium ion conductivity as an electrolyte.
  • the inventors of the present invention conducted intensive studies on reduction of lithium ion conduction resistance, which is a problem of all solid lithium ion secondary batteries. As a result, by providing a coating layer having a feature of expanding and contracting due to lithium ion absorption / desorption around the active material, deterioration in performance due to repeated charging and discharging was suppressed.
  • the covering layer can reduce the volume change of the active material, and can suppress the separation of the interface with the solid electrolyte.
  • the present inventors have led to the development of a low melting point oxide glass material having lithium ion conductivity.
  • the low melting point oxide glass containing at least one of vanadium oxide and tellurium or phosphorus has a feature of expansion and contraction due to absorption and release of lithium ions.
  • the oxide glass material used for the coating layer contains at least one of vanadium and tellurium or phosphorus, has lithium ion conductivity, and has a property of expanding and contracting due to absorption and release of lithium ions.
  • the positive and negative electrode active material particles and the solid electrolyte can be obtained by the expansion and contraction of the positive and negative electrode active materials during charge and discharge.
  • the contact surfaces of the particles peel off, preventing the lithium ion conducting network from breaking up. Thereby, the lithium ion conductivity can be maintained even when the charge and discharge cycle is repeated, and the battery performance can be suppressed from being deteriorated.
  • a conductive material powder such as acetylene black or a metal powder may be added to the covering layer in order to enhance the electron conductivity in the electrode, if necessary.
  • the oxide glass has a low melting point, specifically, a softening point of 500 ° C. or less.
  • the coating treatment is performed at a high temperature of 700 ° C. to 1200 ° C., but in the treatment at such a high temperature, the reaction of the active material and the solid electrolyte coating layer results in the active material particles and the coating layer An altered layer may occur at the layer interface.
  • the contact surface may peel off or a crack may occur in the coating layer at the time of temperature decrease after heat treatment at high temperature. is there.
  • the covering layer made of oxide glass may be provided on solid electrolyte particles in addition to the positive and negative electrode active material particles.
  • solid electrolyte particles are bound with each other by using a binder or hot pressed to form a solid electrolyte layer.
  • the binder does not have lithium ion conductivity, and thus solid electrolyte particles are bound to one another. Even if it is worn, that part does not contribute to lithium ion conduction. Therefore, there is a problem that a sufficient lithium ion conduction path is not formed, and the ion conduction resistance is increased.
  • a solid electrolyte particle is provided with a coating layer made of the oxide glass of the present invention
  • the coated solid electrolyte particle is dispersed in a solvent and coated in a sheet, and then the softening point of the oxide glass is obtained.
  • the solid electrolyte particles can be bound with a material having lithium ion conductivity, so the contact area between the solid electrolyte particles becomes wide, and the lithium ion conductivity is greatly improved.
  • the oxide glass coating layer according to the present invention has a low softening point of 500 ° C.
  • FIG. 1 is a view showing an example of a positive electrode active material particle having a covering layer 2 in which a positive electrode active material 1 is coated with an oxide glass.
  • the covering layer 2 made of oxide glass is characterized in that its volume expands and contracts due to the absorption and release of lithium ions 3.
  • the lithium ion 3 is released from the positive electrode active material 1 by charging and the positive electrode active material 1 contracts, the lithium ion 3 released from the positive electrode active material is inserted into the oxide glass coated with the positive electrode active material 1 Layer 2 expands. As a result, the volume change of the whole active material particle can be suppressed.
  • the oxide glass may be an amorphous so-called ordinary glass or a crystallized glass in which crystals are precipitated in an amorphous glass matrix.
  • amorphous oxide glass is superior in coverage to crystallized glass.
  • crystallized glass is more excellent in lithium ion conductivity. Therefore, when the periphery of the active material is coated with amorphous oxide glass, and active material particles having this coating layer are bonded with crystalline oxide glass, the lithium ion conductivity is particularly excellent. It becomes possible to form an electrode.
  • the oxide glass is characterized by containing vanadium as a main component and at least one selected from tellurium and phosphorus as another component.
  • iron, manganese, tungsten, molybdenum, barium, cobalt or the like can be added to the oxide glass to control crystallinity, a softening point, and a thermal expansion coefficient.
  • the softening point of the oxide glass is preferably 500 ° C. or less, and more preferably the softening point is 400 ° C. or less.
  • the softening point of the oxide glass forming the coating layer of the solid electrolyte is that of the oxide glass forming the coating layer of the active material. It is preferable to be higher than the softening point. In some cases, heating may be performed when the battery is manufactured by combining the positive electrode, the negative electrode, and the electrolyte, and by raising the softening point of the electrolyte, problems such as short circuit between the positive and negative electrodes are less likely to occur.
  • the amount of oxide glass to be coated is changed because the degree of expansion and contraction varies depending on the type of active material, but the amount of oxide glass added is 1% by volume or more and 30% by volume in terms of volume with respect to the active material It is desirable that If it is less than 1% by volume, the active material can not be sufficiently coated, and a sufficient effect of the covering layer can not be obtained. If it is more than 30% by volume, the lithium ion contributes to charge and discharge when forming the electrode. This is because the amount decreases and the capacity of the battery decreases.
  • a known positive electrode active material capable of inserting and extracting lithium ions can be used.
  • it can be represented by LiMO 2 (M is at least one transition metal), and M includes Ni, Co, Mn, Fe, Ti, Zr, Al, Mg, Cr, V and the like.
  • M is at least one transition metal
  • M includes Ni, Co, Mn, Fe, Ti, Zr, Al, Mg, Cr, V and the like.
  • a part of manganese or cobalt or nickel such as lithium manganate or lithium cobaltate or lithium nickelate represented by LiMO 2 may be substituted with one or two transition metals, or magnesium or aluminum. It can be used even if it substitutes with a metal element.
  • oxide glass containing vanadium as a main component is used as the covering material, if crystallized glass containing vanadium is used as the positive electrode active material, adhesion between the active material and the covering layer and transfer of lithium ions are further increased. It becomes good.
  • a known negative electrode active material capable of inserting and extracting lithium ions can be used as the negative electrode active material.
  • a carbon material typified by graphite an alloy material such as a TiSn alloy or a TiSi alloy, a nitride such as LiCoN, or an oxide such as Li 4 Ti 5 O 12 can be used.
  • lithium foil may be used.
  • the solid electrolyte material which conducts lithium ion can be used.
  • a nonflammable inorganic solid electrolyte is preferred.
  • a sulfide glass represented by lithium halides such as LiCl and LiI
  • Oxide glasses represented by Li 3.4 V 0.6 Si 0.4 O 4 , Li 2 P 2 O 6 and the like, and perovskite oxides represented by Li 0.34 La 0.51 TiO 2.94 and the like can be used.
  • the material of an oxide type has high stability with respect to water or oxygen rather than sulfide glass, and is preferable.
  • the method of coating oxide glass is not particularly limited.
  • a positive and negative electrode active material or a solid electrolyte and oxide glass are mixed at a predetermined ratio, coated by heat treatment at a temperature above the softening point of the oxide glass, and then crushed by a ball mill etc.
  • a method of coating the particles by heat treatment at a temperature above the softening point of the oxide glass, etc. may be mentioned.
  • the particle size of the oxide glass particles is smaller than the particle size of the particles to be coated Is desirable.
  • a present Example is an example which coat
  • an oxide glass coating material was produced.
  • As raw materials 255 g of vanadium pentoxide (V 2 O 5 ) powder, 30 g of phosphorus pentoxide (P 2 O 5 ) powder, and 15 g of cobalt oxide (CoO) powder are mixed, charged into a platinum crucible, and an electric furnace It was kept at 1100 ° C. for 2 hours. The temperature rising rate was 10 ° C./min. In addition, during heating, the material in the platinum crucible was stirred so as to be uniform. The sample after 2 hours passed was taken out of the electric furnace, poured on a stainless steel plate preheated to 300 ° C., and naturally cooled to obtain oxide glass (A). The softening point of the obtained glass measured by differential thermal analysis was 302 ° C., and the crystallization temperature was 369 ° C. The produced oxide glass (A) was crushed using a ball mill so that the average particle diameter was about 1 ⁇ m.
  • ⁇ Positive electrode active material particles LiCoO 2 powder with an average particle diameter of 10 ⁇ m was used as the positive electrode active material. Mix 95% by volume of LiCoO 2 powder and ketjen black as a conductive material, mix 85% by volume of the oxide glass (A) powder prepared with this mixture powder, and treat for 10 minutes using a ball mill By doing this, composite particles were produced.
  • the composite glass particles were treated for 30 minutes in dry air at 315 ° C., which is higher than the softening point of the oxide glass, to prepare oxide glass-coated active material particles.
  • a present Example is an example which produced the electrode for lithium ion secondary batteries using the positive electrode active material particle produced in Example 1.
  • FIG. 1 A present Example is an example which produced the electrode for lithium ion secondary batteries using the positive electrode active material particle produced in Example 1.
  • NMP N-methyl-2-pyrrolidone
  • the positive electrode paste was applied to a 20 ⁇ m thick aluminum foil, dried and heat-formed at 315 ° C. higher than the melting point of the oxide glass (A) to obtain a 120 ⁇ m thick positive electrode sheet.
  • the resultant was punched into a disk shape having a diameter of 14 mm to form a positive electrode layer.
  • a present Example is an example which coat
  • ⁇ Anode active material particles As the negative electrode active material, Li 4 Ti 5 O 12 powder having an average particle diameter of 10 ⁇ m was used. Li 4 Ti 5 O 12 powder Ketjen black as a conductive material 95 was mixed with 5% by volume, mixing the same oxide glass (A) powder as that used in the mixture powder and the positive electrode in 85:15 volume% And treated for 10 minutes using a ball mill to produce composite particles.
  • the composite glass particles were treated for 30 minutes in dry air at 315 ° C., which is higher than the softening point of the oxide glass, to prepare oxide glass-coated active material particles.
  • a present Example is an example which produced the electrode for lithium ion secondary batteries using the negative electrode active material particle produced in Example 3.
  • FIG. 1 A present Example is an example which produced the electrode for lithium ion secondary batteries using the negative electrode active material particle produced in Example 3.
  • the negative electrode paste was applied to a 20 ⁇ m thick copper foil, dried and heat-formed at 315 ° C. higher than the melting point of the oxide glass (A) to obtain a 120 ⁇ m thick negative electrode sheet.
  • the resultant was punched into a disk shape having a diameter of 14 mm to form a negative electrode layer.
  • the present example is an example in which an all solid lithium ion secondary battery was produced using Example 2 and Example 4.
  • an oxide glass coating material for a solid electrolyte was produced.
  • As raw materials 240 g of vanadium pentoxide (V 2 O 5 ) powder, 30 g of phosphorus pentoxide (P 2 O 5 ) powder, and 30 g of ferric oxide (Fe 2 O 3 ) powder are mixed and charged into a platinum crucible And kept at 1100 ° C. for 2 hours using an electric furnace. The temperature rising rate was 10 ° C./min. In addition, during heating, the material in the platinum crucible was stirred so as to be uniform.
  • the sample after 2 hours passed was taken out of the electric furnace, poured on a stainless steel plate preheated to 300 ° C., and naturally cooled to obtain oxide glass (B).
  • the softening point of the obtained glass measured by differential thermal analysis was 352 ° C., and the crystallization temperature was 422 ° C.
  • the produced oxide glass (B) was ground using a ball mill so that the average particle size was about 1 ⁇ m.
  • LATP having an average particle size of 5 ⁇ m was used. 95 volume% of LATP powder and 5 volume% of oxide glass (B) powder were mixed, this was thrown into NMP, and the solid electrolyte paste which adjusted viscosity to 20 Pa.s was obtained.
  • the solid electrolyte paste is applied to a 50 ⁇ m thick polyimide sheet, and drying and thermoforming are performed at 365 ° C., which is a temperature higher than the softening point of the oxide glass (B), for the purpose of glass coating treatment of the solid electrolyte A solid electrolyte sheet with a thickness of 100 ⁇ m was obtained. The resultant was punched into a disk shape having a diameter of 15 mm and separated from the polyimide sheet to form a solid electrolyte layer.
  • LiCoO 2 powder with an average particle diameter of 10 ⁇ m was used as the positive electrode active material. 8 g of LiCoO 2 powder, 1.5 g of LATP having an average particle diameter of 5 ⁇ m as a lithium ion conductor in the positive electrode layer, and 0.5 g of ketjen black as a conductive material are mixed, and 10 g of this mixed powder is polyvinylidene fluoride 1.0 g of this was added to NMP to obtain a positive electrode paste whose viscosity was adjusted to 20 Pa ⁇ s.
  • the positive electrode paste was applied to a 20 ⁇ m-thick aluminum foil, subjected to heating and drying treatment, and a 120 ⁇ m-thick positive electrode sheet was obtained.
  • the resultant was punched into a disk shape having a diameter of 14 mm to form a positive electrode layer.
  • ⁇ Negative electrode layer> Li 4 Ti 5 O 12 powder having an average particle diameter of 10 ⁇ m was used. 8 g of Li 4 Ti 5 O 12 powder, 1.5 g of LATP having an average particle diameter of 5 ⁇ m as a lithium ion conductor in the negative electrode layer, and 0.5 g of ketjen black as a conductive material, and 10 g of this mixed powder Then, 0.5 g of polyvinylidene fluoride was added thereto, and this was charged into NMP to obtain a negative electrode paste whose viscosity was adjusted to 20 Pa ⁇ s.
  • the negative electrode paste was applied to a copper foil of 20 ⁇ m in thickness, subjected to heat molding and drying treatment, to obtain a negative electrode sheet of 120 ⁇ m in thickness.
  • the resultant was punched into a disk shape having a diameter of 14 mm to form a negative electrode layer.
  • Solid electrolyte layer For the solid electrolyte, LATP having an average particle size of 5 ⁇ m was used. A solid electrolyte paste having a viscosity adjusted to 20 Pa ⁇ s was obtained by mixing 9.5 g of LATP powder and 0.5 g of polyvinylidene fluoride and introducing this into NMP. This solid electrolyte paste was applied to a 50 ⁇ m thick polyimide sheet and dried to obtain a 100 ⁇ m thick solid electrolyte sheet. The resultant was punched into a disk shape having a diameter of 15 mm and separated from the polyimide sheet to form a solid electrolyte layer.
  • Example 5 (Evaluation) Initial capacity measurement, internal resistance measurement, and charge and discharge cycle tests were performed on the batteries produced in Example 5 and Comparative Example. As a result, no significant difference was found in the initial capacities of the batteries produced in Example 5 and Comparative Example. On the other hand, regarding the internal resistance, the value of Example 5 is about 40% smaller than the internal resistance of the comparative example, and it is clear that the all solid lithium ion secondary battery of the example is superior.
  • the positive and negative electrode active material particles are coated with oxide glass having lithium ion conductivity, and it is estimated that the resistance is the highest in the battery reaction, and the transfer of lithium ions at the interface between the active material particles and the solid electrolyte In the solid electrolyte layer, by covering the solid electrolyte particles with an oxide glass layer having lithium ion conductivity, lithium ion conduction is formed when the solid electrolyte layer is formed. It is considered to be due to the development of the path.
  • the life of the all-solid-state lithium ion secondary battery of this example was significantly improved. This is because, even if the volume change of the active material occurs due to the insertion and desorption of lithium ions during charge and discharge, the coating layer expands and contracts due to the insertion and detachment of lithium ions in the oxide glass, and the interface It is considered that the decrease in performance could be suppressed by relieving the stress and maintaining the lithium ion conduction path.
  • the all-solid-state lithium ion secondary battery of this example is superior to the comparative example and superiority is confirmed.
  • the all-solid-state lithium ion secondary battery which used the solid electrolyte for electrolyte as an example was described in the present Example, you may apply to the lithium ion secondary battery which uses a liquid electrolyte for electrolyte. This is usually because when the positive electrode or the negative electrode is formed using a binder, the portion of the surface of the active material in contact with the binder is not in direct contact with the electrolyte solution which is a lithium ion conductive material, It is difficult for lithium ion to occlude and release.
  • the electrode when the electrode is formed by providing the covering layer of oxide glass on the positive and negative electrode active materials, the electrode does not contain the binder having no ion conductivity in the electrode. It can be made. Since the entire surface of the active material is in contact with the lithium ion conductor, insertion and extraction of lithium ions from the entire surface easily proceeds, and capacity increase and charge / discharge at a high rate become possible.
  • It relates to a lithium ion secondary battery, and can be used for an all solid lithium ion secondary battery that does not use a liquid as an electrolyte.
  • positive electrode active material 2; low melting point glass coating layer, 3; lithium ion, 4; solid electrolyte layer, 5; positive electrode, 6; positive electrode current collector, 7; negative electrode, 8; negative electrode current collector.

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Abstract

Provided is a highly safe all-solid-state lithium ion secondary battery which maintains lithium ion conductivity, suppresses performance deterioration due to repetition of charge/discharge cycles, and has a long service life. In order to achieve the above-mentioned objective, a lithium ion secondary battery of the present invention is provided with a positive electrode, a negative electrode and a solid electrolyte, and is characterized in that a positive electrode active material and/or a negative electrode active material is covered with a coating layer that is formed of glass containing vanadium and phosphorus and/or tellurium. In addition, positive electrode active material particles or negative electrode active material particles, which achieve the above-mentioned objective, are characterized in that the surface of the active material is covered with a coating layer that is formed of glass containing vanadium and phosphorus and/or tellurium.

Description

リチウムイオン二次電池用活物質粒子およびそれを用いたリチウムイオン二次電池Active material particles for lithium ion secondary battery and lithium ion secondary battery using the same
　本発明は、リチウムイオン二次電池用活物質粒子、及びそれを用いたリチウムイオン二次電池に係る。 The present invention relates to a lithium ion secondary battery active material particle and a lithium ion secondary battery using the same.
　リチウムイオン二次電池は、原子量が小さく、イオン化傾向が高いことから、他の二次電池と比較して体積エネルギー密度および重量エネルギー密度が高い。そのため、携帯電話やノートＰＣなどのポータブル機器用電源として広く使われている。さらに、地球温暖化防止や、化石燃料枯渇問題から、ハイブリッド自動車および電気自動車用電源、太陽光発電や風力発電などの再生可能エネルギーを利用した発電システムの電力貯蔵用電源などへの適用も進められている。現在実用化されているリチウムイオン二次電池は、その多くが電解質に可燃性の有機系電解質溶液を使用している。そのため、液漏れや発火などの危険性があり、これらの危険性のない、高安全なリチウムイオン二次電池の開発が望まれている。 A lithium ion secondary battery has a high atomic energy density and a high gravimetric energy density compared to other secondary batteries because of its low atomic weight and high ionization tendency. Therefore, it is widely used as a power source for portable devices such as mobile phones and notebook PCs. Furthermore, because of global warming prevention and fossil fuel exhaustion problems, application to power sources for power storage of power generation systems using renewable energy such as solar power generation and solar power generation and solar power generation is also promoted. ing. Most of lithium ion secondary batteries put to practical use at present use a flammable organic electrolyte solution as the electrolyte. Therefore, there is a risk such as liquid leakage and ignition, and the development of a highly safe lithium ion secondary battery free of these risks is desired.
　液漏れや発火の危険性がない電池として、電解質にリチウムイオン伝導性を有する不燃性の固体電解質を用いた全固体リチウムイオン二次電池の開発が各所で進められている。しかし、現状の全固体リチウムイオン二次電池については、液体電解質のように、正負極活物質表面と電解質が十分に接しておらず、正負極活物質と固体電解質の接触抵抗が高くなる問題がある。さらに、正負極活物質は、電池の充放電に伴いリチウムイオンが出入りするため、体積膨張・収縮するが、これにより正負極活物質と固体電解質の接触面が剥離、リチウムイオン伝導ネットワークが分断される。そのため、充放電サイクルを繰り返すと、次第にリチウムイオン伝導抵抗が増加し、特性が大幅に低下してしまう。 As a battery having no risk of liquid leakage or ignition, development of an all solid lithium ion secondary battery using an incombustible solid electrolyte having lithium ion conductivity as an electrolyte is under way at various places. However, with current all solid lithium ion secondary batteries, as with liquid electrolytes, the surface of the positive and negative electrode active material is not in sufficient contact with the electrolyte, and the contact resistance between the positive and negative electrode active material and the solid electrolyte increases. is there. Furthermore, since lithium ions move in and out with the charge and discharge of the battery, the positive and negative electrode active materials expand and contract in volume, whereby the contact surfaces of the positive and negative electrode active materials and the solid electrolyte peel off and the lithium ion conduction network is divided. Ru. Therefore, when the charge and discharge cycle is repeated, the lithium ion conduction resistance is gradually increased, and the characteristics are significantly reduced.
　特開２００３－５９４９２号公報（特許文献１）では、リチウム二次電池の充放電に伴う活物質の膨張・収縮に起因する電池寸法の変化、内部抵抗の増大、および大電流での充放電性能の劣化を、導電剤およびリチウムイオン伝導性無機固体電解質を含む被覆層で被覆された活物質粒子を用いて解決することが提案されている。全固体リチウムイオン二次電池の活物質表面を、リチウムイオン伝導性を有する堅いガラス状の固体電解質を主成分とする層で被覆したことで、活物質中にリチウムイオンが挿入された際に活物質が膨張するのを、活物質を覆う堅い被覆層で抑えることができる。 In Japanese Patent Application Laid-Open No. 2003-59492 (Patent Document 1), a change in battery dimensions, an increase in internal resistance, and a charge / discharge performance at a large current due to expansion / contraction of an active material accompanying charge / discharge of a lithium secondary battery. It has been proposed to solve the deterioration of the above using active material particles coated with a covering layer containing a conductive agent and a lithium ion conductive inorganic solid electrolyte. The surface of the active material of the all solid lithium ion secondary battery is covered with a layer mainly composed of a hard glassy solid electrolyte having lithium ion conductivity, so that it is active when lithium ions are inserted into the active material. The expansion of the substance can be suppressed by the hard coating layer covering the active material.
特開２００３－５９４９２号公報Japanese Patent Application Publication No. 2003-59492
　しかし、特許文献１の堅い固体電解質では、リチウムイオンの放出により活物質粒子が収縮する際、被覆層が堅いため活物質粒子の体積変化に追従できない。そのため、活物質粒子表面と固体電解質被覆層の接触面が剥離、リチウムイオンの伝導ネットワークが分断されることで、特性が低下してしまう。 However, in the hard solid electrolyte of Patent Document 1, when the active material particles contract due to the release of lithium ions, the covering layer is hard to follow the volume change of the active material particles. For this reason, the contact surface of the active material particle surface and the solid electrolyte coating layer is peeled off and the lithium ion conduction network is divided, resulting in deterioration of the characteristics.
　上記課題を解決するための本発明のリチウムイオン二次電池は、正極及び負極と、固体電解質とを備え、正極活物質、負極活物質の少なくともいずれかが、リチウムイオンを吸蔵・放出して膨張・収縮する性質を備える酸化物ガラスを含む被覆層で被覆されていることを特徴とする。 The lithium ion secondary battery of the present invention for solving the above problems includes a positive electrode, a negative electrode, and a solid electrolyte, and at least one of a positive electrode active material and a negative electrode active material occludes and releases lithium ions to expand. It is characterized in that it is coated with a coating layer containing oxide glass having a shrinking property.
　また、上記課題を解決する本発明の正極活物質粒子または負極活物質粒子は、活物質の表面を、リチウムイオンを吸蔵・放出して膨張・収縮する性質を備える酸化物ガラスを含む被覆層で被覆されていることを特徴とする。 Further, the positive electrode active material particles or the negative electrode active material particles according to the present invention for solving the above problems are a coating layer including an oxide glass having a property of absorbing and releasing lithium ions to expand and contract the surface of the active material. It is characterized by being covered.
　被覆層は、リチウムイオン伝導性を備え、バナジウムと、リンまたはテルルの少なくともいずれかを含有する低融点の酸化物ガラスとすることが好ましい。 The coating layer is preferably a low melting point oxide glass having lithium ion conductivity and containing vanadium and / or phosphorus or tellurium.
　上記構成によれば、高安全かつ長寿命な全固体リチウムイオン二次電池を提供することが可能となる。充放電に伴う正負極活物質の膨張・収縮により、正負極活物質と固体電解質の接触面が剥離し、リチウムイオン伝導ネットワークが分断されるのを防止する。その結果、リチウムイオン二次電池のリチウムイオン伝導性を維持し、充放電サイクルの繰り返しにより性能が低下するのを抑制することができる。 According to the above configuration, it is possible to provide a highly safe and long life all solid lithium ion secondary battery. By the expansion and contraction of the positive and negative electrode active materials accompanying charge and discharge, the contact surfaces of the positive and negative electrode active materials and the solid electrolyte are peeled off to prevent the lithium ion conductive network from being divided. As a result, the lithium ion conductivity of the lithium ion secondary battery can be maintained, and the performance deterioration due to the repetition of charge and discharge cycles can be suppressed.
正極活物質を酸化物ガラスで被覆した活物質粒子の模式図。The schematic diagram of the active material particle which coat | covered the positive electrode active material with oxide glass. 全固体リチウムイオン二次電池の模式図。The schematic diagram of an all-solid-state lithium ion secondary battery.
　図２は、全固体リチウムイオン二次電池の模式図である。正極５及び負極７の間に固体電解質層４が配置されている。全固体リチウムイオン二次電池は、電解質にリチウムイオン伝導性を有する不燃性の固体電解質を使用しているため安全性が高い。本発明者らは、全固体リチウムイオン二次電池の課題であるリチウムイオン伝導抵抗低減について鋭意検討を重ねた。その結果、活物質の周囲に、リチウムイオンの吸蔵・放出により膨張・収縮する特徴を有する被覆層を設けることにより、充放電の繰り返しにより性能が低下するのを抑制した。被覆層が活物質の体積変化を緩和し、固体電解質との界面の剥離を抑制できる。 FIG. 2 is a schematic view of an all solid lithium ion secondary battery. The solid electrolyte layer 4 is disposed between the positive electrode 5 and the negative electrode 7. The all solid lithium ion secondary battery is highly safe because it uses a nonflammable solid electrolyte having lithium ion conductivity as an electrolyte. The inventors of the present invention conducted intensive studies on reduction of lithium ion conduction resistance, which is a problem of all solid lithium ion secondary batteries. As a result, by providing a coating layer having a feature of expanding and contracting due to lithium ion absorption / desorption around the active material, deterioration in performance due to repeated charging and discharging was suppressed. The covering layer can reduce the volume change of the active material, and can suppress the separation of the interface with the solid electrolyte.
　また、本発明者らは、リチウムイオン伝導性を有する、低融点の酸化物ガラス材料の開発に至った。この酸化バナジウムおよびテルルまたはリンの少なくともいずれかを含む低融点酸化物ガラスは、リチウムイオンの吸蔵・放出により膨張・収縮する特徴を有する。この酸化物ガラス材料で正負極活物質粒子を被覆することにより、全固体リチウムイオン二次電池の課題である、リチウムイオン伝導抵抗を大幅に低減することに成功した。 In addition, the present inventors have led to the development of a low melting point oxide glass material having lithium ion conductivity. The low melting point oxide glass containing at least one of vanadium oxide and tellurium or phosphorus has a feature of expansion and contraction due to absorption and release of lithium ions. By covering the positive and negative electrode active material particles with this oxide glass material, we succeeded in significantly reducing the lithium ion conduction resistance, which is the problem of the all solid lithium ion secondary battery.
　被覆層に使用する酸化物ガラス材料は、バナジウムおよびテルルまたはリンの少なくともいずれかを含み、リチウムイオン伝導性を有し、かつリチウムイオンの吸蔵・放出により膨張・収縮する性質を有する。正極活物質粒子、負極活物質粒子の少なくともいずれかの表面をこのような酸化物ガラスで被覆することで、充放電に伴う正負極活物質の膨張・収縮により、正負極活物質粒子と固体電解質粒子の接触面が剥離し、リチウムイオン伝導ネットワークが分断されるのを防止する。これにより、充放電サイクルの繰り返しを行ってもリチウムイオン伝導性を維持し、電池性能が低下するのを抑制できる。被覆層には、電極内での電子伝導性を高める目的で、アセチレンブラックや金属粉末などの導電材粉末を必要に応じて加えてもよい。 The oxide glass material used for the coating layer contains at least one of vanadium and tellurium or phosphorus, has lithium ion conductivity, and has a property of expanding and contracting due to absorption and release of lithium ions. By covering the surface of at least one of the positive electrode active material particles and the negative electrode active material particles with such an oxide glass, the positive and negative electrode active material particles and the solid electrolyte can be obtained by the expansion and contraction of the positive and negative electrode active materials during charge and discharge. The contact surfaces of the particles peel off, preventing the lithium ion conducting network from breaking up. Thereby, the lithium ion conductivity can be maintained even when the charge and discharge cycle is repeated, and the battery performance can be suppressed from being deteriorated. A conductive material powder such as acetylene black or a metal powder may be added to the covering layer in order to enhance the electron conductivity in the electrode, if necessary.
　さらに、酸化物ガラスが低融点、具体的には軟化点が500℃以下であることが好ましい。例えば、特許文献１では、700℃～1200℃と高温で被覆処理しているが、このような高温での処理においては、活物質と固体電解質被覆層の反応により、活物質粒子と被覆層の層界面に変質層が生じる可能性がある。また、活物質粒子と、活物質粒子を被覆する固体電解質の熱膨張係数の違いから、高温での加熱処理後の降温時に接触面が剥離したり、被覆層に割れが生じたりする可能性がある。軟化点を低温とすることで、電池の特性に悪影響を及ぼす危険性を回避できる。 Furthermore, it is preferable that the oxide glass has a low melting point, specifically, a softening point of 500 ° C. or less. For example, in Patent Document 1, the coating treatment is performed at a high temperature of 700 ° C. to 1200 ° C., but in the treatment at such a high temperature, the reaction of the active material and the solid electrolyte coating layer results in the active material particles and the coating layer An altered layer may occur at the layer interface. In addition, due to the difference in thermal expansion coefficient between the active material particles and the solid electrolyte covering the active material particles, there is a possibility that the contact surface may peel off or a crack may occur in the coating layer at the time of temperature decrease after heat treatment at high temperature. is there. By setting the softening point to a low temperature, the risk of adversely affecting the characteristics of the battery can be avoided.
　酸化物ガラスよりなる被覆層は、正負極活物質粒子のほか、固体電解質粒子に設けてもよい。通常、全固体リチウムイオン電池においては、固体電解質粒子同士を、バインダを用いて結着する、あるいは熱プレスするなどして固体電解質層を形成する。しかし、いずれの方法を用いても、固体電解質粒子は堅い粒子なので、粒子同士の接触は点接触となってしまうし、バインダについては、リチウムイオン伝導性を持たないため、固体電解質粒子同士を結着していても、その部分はリチウムイオン伝導には寄与しない。そのため、十分なリチウムイオン伝導パスが形成されず、イオン伝導抵抗が高くなってしまうという問題があった。これに対し、固体電解質粒子に本発明の酸化物ガラスよりなる被覆層を設けた場合は、被覆した固体電解質粒子を溶媒に分散させて、シート状に塗布した後、酸化物ガラスの軟化点よりも高い温度で熱処理することで、固体電解質粒子を、リチウムイオン伝導性を有する材料で結着することができるので、固体電解質粒子同士の接触面積が広くなり、リチウムイオン伝導性が大幅に向上する。なお、本発明の酸化物ガラス被覆層は、固体電解質粒子に用いた場合についても、軟化点が500℃以下と低いことから、被覆処理の際に固体電解質と酸化物ガラス界面への変質層の形成を防止できるとともに、固体電解質と被覆層の熱膨張係数の差に起因する剥がれや割れの危険性を低減できる。 The covering layer made of oxide glass may be provided on solid electrolyte particles in addition to the positive and negative electrode active material particles. Usually, in the all solid lithium ion battery, solid electrolyte particles are bound with each other by using a binder or hot pressed to form a solid electrolyte layer. However, regardless of which method is used, since solid electrolyte particles are hard particles, the contact between the particles results in point contact, and the binder does not have lithium ion conductivity, and thus solid electrolyte particles are bound to one another. Even if it is worn, that part does not contribute to lithium ion conduction. Therefore, there is a problem that a sufficient lithium ion conduction path is not formed, and the ion conduction resistance is increased. On the other hand, when a solid electrolyte particle is provided with a coating layer made of the oxide glass of the present invention, the coated solid electrolyte particle is dispersed in a solvent and coated in a sheet, and then the softening point of the oxide glass is obtained. By heat-treating at a high temperature as well, the solid electrolyte particles can be bound with a material having lithium ion conductivity, so the contact area between the solid electrolyte particles becomes wide, and the lithium ion conductivity is greatly improved. . The oxide glass coating layer according to the present invention has a low softening point of 500 ° C. or less even when used for solid electrolyte particles, and therefore, an altered layer is formed at the interface between the solid electrolyte and the oxide glass during coating treatment. While being able to prevent formation, it is possible to reduce the risk of peeling or cracking due to the difference in thermal expansion coefficient between the solid electrolyte and the covering layer.
　上記の構成によれば、全固体リチウムイオン二次電池の課題であった、正負極活物質の膨張・収縮によるリチウムイオン伝導ネットワークの分断が防止できる。これにより、リチウムイオン伝導性を維持し、充放電サイクルの繰り返しにより性能が低下するのを抑制できる。従って高安全で長寿命な全固体リチウムイオン二次電池を提供することが可能となる。 According to the above configuration, it is possible to prevent the division of the lithium ion conduction network due to the expansion and contraction of the positive and negative electrode active materials, which is a problem of the all solid lithium ion secondary battery. Thereby, lithium ion conductivity can be maintained, and it can suppress that a performance falls by repetition of a charging / discharging cycle. Therefore, it is possible to provide a highly safe and long life all solid lithium ion secondary battery.
　以下、本発明の全固体リチウムイオン二次電池について、さらに詳細を説明する。 Hereinafter, the details of the all solid lithium ion secondary battery of the present invention will be described.
　図１は、正極活物質１を酸化物ガラスで被覆した被覆層２を有する正極活物質粒子の例を示す図である。酸化物ガラスよりなる被覆層２は、リチウムイオン３の吸蔵・放出により体積が膨張・収縮する特徴を有する。充電により正極活物質１からリチウムイオン３が放出されて、正極活物質１が収縮する際、正極活物質１を被覆した酸化物ガラスに正極活物質から放出されたリチウムイオン３が挿入され、被覆層２が膨張する。その結果、活物質粒子全体の体積変化を抑制できる。これにより活物質粒子と接触する固体電解質の界面の剥離が生じにくく、リチウムイオン伝導ネットワークの分断が防止される。従って、充放電を繰り返しても電池性能の低下が抑制され、電池の長寿命化を図ることができる。 FIG. 1 is a view showing an example of a positive electrode active material particle having a covering layer 2 in which a positive electrode active material 1 is coated with an oxide glass. The covering layer 2 made of oxide glass is characterized in that its volume expands and contracts due to the absorption and release of lithium ions 3. When the lithium ion 3 is released from the positive electrode active material 1 by charging and the positive electrode active material 1 contracts, the lithium ion 3 released from the positive electrode active material is inserted into the oxide glass coated with the positive electrode active material 1 Layer 2 expands. As a result, the volume change of the whole active material particle can be suppressed. As a result, peeling of the interface of the solid electrolyte in contact with the active material particles is unlikely to occur, and separation of the lithium ion conductive network is prevented. Therefore, even if charge and discharge are repeated, deterioration of the battery performance is suppressed, and the battery life can be extended.
　酸化物ガラスは、非晶質のいわゆる通常のガラスのほか、非晶質のガラスマトリクス中に結晶が析出した結晶化ガラスでもよい。一般的に、結晶化ガラスよりも非晶質の酸化物ガラスの方が被覆性に優れる。また、結晶化ガラスの方がリチウムイオン伝導性に優れる。従って、活物質の周囲を非晶質の酸化物ガラスで被覆し、かつ、この被覆層を有する活物質粒子を、結晶質の酸化物ガラスで結着すれば、特にリチウムイオン伝導性に優れた電極を形成することが可能となる。 The oxide glass may be an amorphous so-called ordinary glass or a crystallized glass in which crystals are precipitated in an amorphous glass matrix. In general, amorphous oxide glass is superior in coverage to crystallized glass. In addition, crystallized glass is more excellent in lithium ion conductivity. Therefore, when the periphery of the active material is coated with amorphous oxide glass, and active material particles having this coating layer are bonded with crystalline oxide glass, the lithium ion conductivity is particularly excellent. It becomes possible to form an electrode.
　酸化物ガラスは、バナジウムが主成分であり、その他の成分として、テルルまたはリンから選ばれる少なくともいずれかを含むことを特徴とする。また、酸化物ガラスには、鉄、マンガン、タングステン、モリブデン、バリウム、コバルトなどを添加し、結晶性や軟化点、熱膨張率を制御することができる。酸化物ガラスの軟化点は５００℃以下であることが好ましく、より好ましくは軟化点が４００℃以下であることが望ましい。正負極活物質や固体電解質とこの酸化物ガラスとを複合化する際、低温での処理が可能となることで、接合面での変質層の生成を防ぐ。さらに、高温での熱処理に比べ、活物質と被覆層の熱膨張係数の差に起因する剥がれや割れの危険性を低減できる。また、低い温度で処理ができることにより、コスト低減にもつながる。 The oxide glass is characterized by containing vanadium as a main component and at least one selected from tellurium and phosphorus as another component. In addition, iron, manganese, tungsten, molybdenum, barium, cobalt or the like can be added to the oxide glass to control crystallinity, a softening point, and a thermal expansion coefficient. The softening point of the oxide glass is preferably 500 ° C. or less, and more preferably the softening point is 400 ° C. or less. When complexing the positive and negative electrode active material or the solid electrolyte with the oxide glass, processing at a low temperature is possible, thereby preventing the formation of a denatured layer on the bonding surface. Furthermore, compared to heat treatment at high temperature, the risk of peeling or cracking due to the difference between the thermal expansion coefficients of the active material and the covering layer can be reduced. In addition, the ability to process at low temperatures leads to cost reduction.
　また、正負極の活物質と、固体電解質の両方に被覆層を設ける場合には、固体電解質の被覆層を形成する酸化物ガラスの軟化点が、活物質の被覆層を形成する酸化物ガラスの軟化点よりも高いことが好ましい。正極、負極、電解質を組み合わせて電池を作製する際に加熱する場合があり、電解質の軟化点を高くすることで正負極の短絡などの問題が生じにくくなるためである。 In the case where the coating layer is provided on both the positive and negative electrode active materials and the solid electrolyte, the softening point of the oxide glass forming the coating layer of the solid electrolyte is that of the oxide glass forming the coating layer of the active material. It is preferable to be higher than the softening point. In some cases, heating may be performed when the battery is manufactured by combining the positive electrode, the negative electrode, and the electrolyte, and by raising the softening point of the electrolyte, problems such as short circuit between the positive and negative electrodes are less likely to occur.
　活物質の種類により膨張、収縮の度合いが異なるため、被覆する酸化物ガラスの量を変化させるが、酸化物ガラスの添加量は、活物質に対し、体積換算で１体積％以上、３０体積％以下であることが望ましい。1体積％以下では、活物質を十分に被覆することができず、被覆層の十分な効果が得られず、３０体積％以上では、電極を形成した際、充放電に寄与するリチウムイオンの絶対量が減少してしまい、電池としての容量が低下してしまうためである。 The amount of oxide glass to be coated is changed because the degree of expansion and contraction varies depending on the type of active material, but the amount of oxide glass added is 1% by volume or more and 30% by volume in terms of volume with respect to the active material It is desirable that If it is less than 1% by volume, the active material can not be sufficiently coated, and a sufficient effect of the covering layer can not be obtained. If it is more than 30% by volume, the lithium ion contributes to charge and discharge when forming the electrode. This is because the amount decreases and the capacity of the battery decreases.
　正極活物質としては、リチウムイオンを吸蔵・放出可能である既知の正極活物質を使用することができる。たとえばＬｉＭＯ2(Ｍは少なくとも1種の遷移金属)で表せるものであり、ＭはＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｔｉ、Ｚｒ、Ａｌ、Ｍｇ、Ｃｒ、Ｖなどが挙げられる。その他にも、ＬｉＭＯ2で表されるマンガン酸リチウムやコバルト酸リチウム、ニッケル酸リチウムなどのマンガンやコバルト、ニッケルの一部を1種または2種の遷移金属で置換したり、マグネシウム、アルムニウムなどの金属元素で置換するなどしたりしても使用することができる。なお、被覆材としてバナジウムを主成分とした酸化物ガラスを使用するため、正極活物質にバナジウムを含む結晶化ガラスを使用すれば、活物質と被覆層界面の密着性やリチウムイオンの授受がさらに良好になる。 As a positive electrode active material, a known positive electrode active material capable of inserting and extracting lithium ions can be used. For example, it can be represented by LiMO 2 (M is at least one transition metal), and M includes Ni, Co, Mn, Fe, Ti, Zr, Al, Mg, Cr, V and the like. In addition, a part of manganese or cobalt or nickel such as lithium manganate or lithium cobaltate or lithium nickelate represented by LiMO 2 may be substituted with one or two transition metals, or magnesium or aluminum. It can be used even if it substitutes with a metal element. In addition, since oxide glass containing vanadium as a main component is used as the covering material, if crystallized glass containing vanadium is used as the positive electrode active material, adhesion between the active material and the covering layer and transfer of lithium ions are further increased. It becomes good.
　負極活物質としては、リチウムイオンを吸蔵・放出可能である既知の負極活物質を使用することができる。たとえば、黒鉛に代表される炭素材料や、ＴｉＳｎ合金、ＴｉＳｉ合金などの合金材料、ＬｉＣｏＮなどの窒化物、Ｌｉ4Ｔｉ5Ｏ12などの酸化物を用いることができる。また、リチウム箔を用いてもよい。 A known negative electrode active material capable of inserting and extracting lithium ions can be used as the negative electrode active material. For example, a carbon material typified by graphite, an alloy material such as a TiSn alloy or a TiSi alloy, a nitride such as LiCoN, or an oxide such as Li 4 Ti 5 O 12 can be used. Alternatively, lithium foil may be used.
　固体電解質としては、特に限定する必要はなく、リチウムイオンを伝導する固体電解質材料を使用できる。なお、安全性の観点から不燃性の無機固体電解質が好ましい。たとえば、ＬｉＣｌ、ＬｉＩなどのハロゲン化リチウム、Ｌｉ2Ｓ－ＳｉＳ2、Ｌｉ3ＰＯ4－Ｌｉ2Ｓ－ＳｉＳ2などに代表される硫化物ガラス、Ｌｉ1.4Ａｌ0.4Ｔｉ1.6（ＰＯ4）3、Ｌｉ3.4Ｖ0.6Ｓｉ0.4Ｏ4、Ｌｉ2Ｐ2Ｏ6などで代表される酸化物ガラス、Ｌｉ0.34Ｌａ0.51ＴｉＯ2.94などで代表されるペロブスカイト型酸化物などが使用できる。なお、酸化物系の材料は、硫化物ガラスよりも水や酸素に対する安定性が高く、好ましい。 It does not need to specifically limit as a solid electrolyte, The solid electrolyte material which conducts lithium ion can be used. From the viewpoint of safety, a nonflammable inorganic solid electrolyte is preferred. For example, a sulfide glass represented by lithium halides such as LiCl and LiI, Li 2 S-SiS 2 , Li 3 PO 4 -Li 2 S-SiS 2 , Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 , Oxide glasses represented by Li 3.4 V 0.6 Si 0.4 O 4 , Li 2 P 2 O 6 and the like, and perovskite oxides represented by Li 0.34 La 0.51 TiO 2.94 and the like can be used. In addition, the material of an oxide type has high stability with respect to water or oxygen rather than sulfide glass, and is preferable.
　酸化物ガラスの被覆方法は特に限定されるものではない。（１）正負極活物質や固体電解質と、酸化物ガラスを所定の比率で混合し、酸化物ガラスの軟化点以上の温度での熱処理を施すことにより被覆した後、ボールミルなどで粉砕して粒子を得る方法や、（２）ボールミル、コールドスプレー、ハイブリダイゼーション、メカノフュージョンなどの方法で、正負極活物質や固体電解質と、酸化物ガラスをあらかじめ複合化した粒子を形成した後、粒子同士が決着しないよう酸化物ガラスの軟化点以上の温度での熱処理を施すことにより、粒子を被覆する方法などが挙げられる。ここで、被覆される粒子と酸化物ガラス粒子との混合性や、熱処理の際の被覆性を高めるためには、酸化物ガラス粒子の粒径が、被覆される粒子の粒径よりも小さいことが望ましい。 The method of coating oxide glass is not particularly limited. (1) A positive and negative electrode active material or a solid electrolyte and oxide glass are mixed at a predetermined ratio, coated by heat treatment at a temperature above the softening point of the oxide glass, and then crushed by a ball mill etc. (2) After forming particles in which the positive and negative electrode active materials and solid electrolyte and oxide glass are complexed in advance by methods such as ball milling, cold spraying, hybridization and mechanofusion A method of coating the particles by heat treatment at a temperature above the softening point of the oxide glass, etc. may be mentioned. Here, in order to enhance the mixability of the particles to be coated and the oxide glass particles, and the coatability at the time of heat treatment, the particle size of the oxide glass particles is smaller than the particle size of the particles to be coated Is desirable.
　以下、実施例にてさらに具体的に説明する。 Hereinafter, the present invention will be described more specifically in the examples.
　本実施例は、正極活物質を、低融点の酸化物ガラスで被覆した例である。 A present Example is an example which coat | covered the positive electrode active material with the oxide glass of low melting | fusing point.
　＜低融点ガラス被覆材＞
　まず、酸化物ガラス被覆材を作製した。原料として、五酸化バナジウム(Ｖ2Ｏ5)粉末２５５ｇと、五酸化リン(Ｐ2Ｏ5)粉末３０ｇ、酸化コバルト(ＣｏＯ)粉末１５ｇを混合し、これを白金るつぼに投入し、電気炉を用いて１１００℃、２時間保持した。なお、昇温速度は１０℃／分とした。また、加熱中は、白金るつぼ内の材料が均一になるよう攪拌した。２時間が経過した試料は、電気炉から取り出し、あらかじめ３００℃に加熱しておいたステンレス板上に流し、これを自然冷却することで酸化物ガラス（Ａ）を得た。得られたガラスの示差熱分析法により測定した軟化点は３０２℃、結晶化温度は３６９℃だった。作製した酸化物ガラス（Ａ）は、ボールミルを用いて、平均粒径が１μｍ程度になるよう粉砕した。 <Low melting point glass coating material>
First, an oxide glass coating material was produced. As raw materials, 255 g of vanadium pentoxide (V 2 O 5 ) powder, 30 g of phosphorus pentoxide (P 2 O 5 ) powder, and 15 g of cobalt oxide (CoO) powder are mixed, charged into a platinum crucible, and an electric furnace It was kept at 1100 ° C. for 2 hours. The temperature rising rate was 10 ° C./min. In addition, during heating, the material in the platinum crucible was stirred so as to be uniform. The sample after 2 hours passed was taken out of the electric furnace, poured on a stainless steel plate preheated to 300 ° C., and naturally cooled to obtain oxide glass (A). The softening point of the obtained glass measured by differential thermal analysis was 302 ° C., and the crystallization temperature was 369 ° C. The produced oxide glass (A) was crushed using a ball mill so that the average particle diameter was about 1 μm.
　＜正極活物質粒子＞
　正極活物質には、平均粒径が１０μｍのＬｉＣｏＯ2粉末を使用した。ＬｉＣｏＯ2粉末と導電材としてケッチェンブラックを９５：５体積％で混合し、この混合物粉末と作製した酸化物ガラス（Ａ）粉末を８５：１５体積％で混合し、ボールミルを用いて１０分間処理することで、複合化粒子を作製した。 <Positive electrode active material particles>
LiCoO 2 powder with an average particle diameter of 10 μm was used as the positive electrode active material. Mix 95% by volume of LiCoO 2 powder and ketjen black as a conductive material, mix 85% by volume of the oxide glass (A) powder prepared with this mixture powder, and treat for 10 minutes using a ball mill By doing this, composite particles were produced.
　この複合化粒子を酸化物ガラスの軟化点よりも高い３１５℃のドライエア―中で３０分間処理することで、酸化物ガラス被覆活物質粒子を作製した。 The composite glass particles were treated for 30 minutes in dry air at 315 ° C., which is higher than the softening point of the oxide glass, to prepare oxide glass-coated active material particles.
　本実施例は、実施例１で作製した正極活物質粒子を用いてリチウムイオン二次電池用電極を作製した例である。 A present Example is an example which produced the electrode for lithium ion secondary batteries using the positive electrode active material particle produced in Example 1. FIG.
　＜正極層＞
　実施例１で作製した正極活物質粒子８．８ｇと、正極層内でのリチウムイオン伝導体として平均粒径が５μｍのＬｉ1.5Ａｌ0.5Ｔｉ1.5（ＰＯ4）3粉末（以下ＬＡＴＰと記述する）を１ｇと、導電材としてケッチェンブラック０．２ｇを混合し、これをＮ－メチル－２－ピロリドン(以下ＮＭＰと記述する)に投入し、粘度を２０Ｐａ・ｓに調整した正極ペーストを得た。 <Positive electrode layer>
8.8 g of the positive electrode active material particles prepared in Example 1 and Li 1.5 Al 0.5 Ti 1.5 (PO 4 ) 3 powder having an average particle diameter of 5 μm as a lithium ion conductor in the positive electrode layer (hereinafter referred to as LATP) 1 g of the above and 0.2 g of ketjen black as a conductive material, and this was added to N-methyl-2-pyrrolidone (hereinafter referred to as NMP) to obtain a positive electrode paste whose viscosity was adjusted to 20 Pa · s. .
　この正極ペーストを厚さ２０μｍのアルミニウム箔に塗布、酸化物ガラス（A）の融点よりも高い３１５℃で乾燥および加熱成形処理を施し、厚さ１２０μｍの正極シートを得た。これを直径１４ｍｍの円盤状に打ち抜き、正極層とした。 The positive electrode paste was applied to a 20 μm thick aluminum foil, dried and heat-formed at 315 ° C. higher than the melting point of the oxide glass (A) to obtain a 120 μm thick positive electrode sheet. The resultant was punched into a disk shape having a diameter of 14 mm to form a positive electrode layer.
　本実施例は、負極活物質を、低融点の酸化物ガラスで被覆した例である。 A present Example is an example which coat | covered the negative electrode active material with the low melting-point oxide glass.
　＜負極活物質粒子＞
　負極活物質には、平均粒径が１０μｍのＬｉ4Ｔｉ5Ｏ12粉末を使用した。Ｌｉ4Ｔｉ5Ｏ12粉末と導電材としてケッチェンブラックを９５：５体積％で混合し、この混合物粉末と正極に使用したものと同じ酸化物ガラス（Ａ）粉末を８５：１５体積％で混合し、ボールミルを用いて１０分間処理することで、複合化粒子を作製した。 <Anode active material particles>
As the negative electrode active material, Li 4 Ti 5 O 12 powder having an average particle diameter of 10 μm was used. Li 4 Ti 5 O 12 powder Ketjen black as a conductive material 95 was mixed with 5% by volume, mixing the same oxide glass (A) powder as that used in the mixture powder and the positive electrode in 85:15 volume% And treated for 10 minutes using a ball mill to produce composite particles.
　この複合化粒子を酸化物ガラスの軟化点よりも高い３１５℃のドライエア―中で３０分間処理することで、酸化物ガラス被覆活物質粒子を作製した。 The composite glass particles were treated for 30 minutes in dry air at 315 ° C., which is higher than the softening point of the oxide glass, to prepare oxide glass-coated active material particles.
　本実施例は、実施例３で作製した負極活物質粒子を用いてリチウムイオン二次電池用電極を作製した例である。 A present Example is an example which produced the electrode for lithium ion secondary batteries using the negative electrode active material particle produced in Example 3. FIG.
　＜負極層＞
　実施例３で作製した負極活物質粒子８．８ｇと、負極層内でのリチウムイオン伝導体として平均粒径が５μｍのＬＡＴＰを１ｇと、導電材としてケッチェンブラック０．２ｇを混合し、これをＮＭＰに投入し、粘度を２０Ｐａ・ｓに調整した負極ペーストを得た。 <Negative electrode layer>
8.8 g of the negative electrode active material particles prepared in Example 3 and 1 g of LATP having an average particle diameter of 5 μm as a lithium ion conductor in the negative electrode layer and 0.2 g of ketjen black as a conductive material are mixed. The mixture was charged into NMP to obtain a negative electrode paste whose viscosity was adjusted to 20 Pa · s.
　この負極ペーストを厚さ２０μｍの銅箔に塗布、酸化物ガラス（A）の融点よりも高い３１５℃で乾燥および加熱成形処理を施し、厚さ１２０μｍの負極シートを得た。これを直径１４ｍｍの円盤状に打ち抜き、負極層とした。 The negative electrode paste was applied to a 20 μm thick copper foil, dried and heat-formed at 315 ° C. higher than the melting point of the oxide glass (A) to obtain a 120 μm thick negative electrode sheet. The resultant was punched into a disk shape having a diameter of 14 mm to form a negative electrode layer.
　本実施例は、実施例２および実施例４を用いて、全固体リチウムイオン二次電池を作製した例である。 The present example is an example in which an all solid lithium ion secondary battery was produced using Example 2 and Example 4.
　＜固体電解質層＞
　まず、固体電解質用の酸化物ガラス被覆材を作製した。原料として、五酸化バナジウム(Ｖ2Ｏ5)粉末２４０ｇと、五酸化リン(Ｐ2Ｏ5)粉末３０ｇ、酸化第二鉄(Ｆｅ2Ｏ3)粉末３０ｇを混合し、これを白金るつぼに投入し、電気炉を用いて１１００℃、２時間保持した。なお、昇温速度は１０℃／分とした。また、加熱中は、白金るつぼ内の材料が均一になるよう攪拌した。２時間が経過した試料は、電気炉から取り出し、あらかじめ３００℃に加熱しておいたステンレス板上に流し、これを自然冷却することで酸化物ガラス（Ｂ）を得た。得られたガラスの示差熱分析法により測定した軟化点は３５２℃、結晶化温度は４２２℃だった。作製した酸化物ガラス（Ｂ）は、ボールミルを用いて、平均粒径が１μｍ程度になるよう粉砕した。 <Solid electrolyte layer>
First, an oxide glass coating material for a solid electrolyte was produced. As raw materials, 240 g of vanadium pentoxide (V 2 O 5 ) powder, 30 g of phosphorus pentoxide (P 2 O 5 ) powder, and 30 g of ferric oxide (Fe 2 O 3 ) powder are mixed and charged into a platinum crucible And kept at 1100 ° C. for 2 hours using an electric furnace. The temperature rising rate was 10 ° C./min. In addition, during heating, the material in the platinum crucible was stirred so as to be uniform. The sample after 2 hours passed was taken out of the electric furnace, poured on a stainless steel plate preheated to 300 ° C., and naturally cooled to obtain oxide glass (B). The softening point of the obtained glass measured by differential thermal analysis was 352 ° C., and the crystallization temperature was 422 ° C. The produced oxide glass (B) was ground using a ball mill so that the average particle size was about 1 μm.
　固体電解質には、平均粒径が５μｍのＬＡＴＰを使用した。ＬＡＴＰ粉末９５体積％と、酸化物ガラス（Ｂ）粉末５体積％を混合、これをＮＭＰに投入し、粘度を２０Ｐａ・ｓに調整した固体電解質ペーストを得た。この固体電解質ペーストを厚さ５０μｍのポリイミドシートに塗布、固体電解質のガラス被覆処理を目的として、酸化物ガラス（Ｂ）の軟化点よりも高い温度である３６５℃で乾燥および加熱成形処理を施し、厚さ１００μｍの固体電解質シートを得た。これを直径１５ｍｍの円盤状に打ち抜き、ポリイミドシートから分離して固体電解質層とした。 For the solid electrolyte, LATP having an average particle size of 5 μm was used. 95 volume% of LATP powder and 5 volume% of oxide glass (B) powder were mixed, this was thrown into NMP, and the solid electrolyte paste which adjusted viscosity to 20 Pa.s was obtained. The solid electrolyte paste is applied to a 50 μm thick polyimide sheet, and drying and thermoforming are performed at 365 ° C., which is a temperature higher than the softening point of the oxide glass (B), for the purpose of glass coating treatment of the solid electrolyte A solid electrolyte sheet with a thickness of 100 μm was obtained. The resultant was punched into a disk shape having a diameter of 15 mm and separated from the polyimide sheet to form a solid electrolyte layer.
　＜電池化＞
　上記の正極層、固体電解質層、負極層を積層し、各々の界面を十分密着させた状態で、正極／固体電解質層、負極／固体電解質層界面の密着性を向上させることを目的として、電気炉中で、酸化物ガラス（Ａ）の軟化点よりも高く、酸化物ガラス（Ｂ）の軟化点よりも低い温度である、３１５℃、１ｈの熱処理をして発電素子を完成させた。得られた発電素子の側面をマスキングし、これをＣＲ２０２５型のコイン電池に組み込み全固体電池を完成させた。 <Battery>
In order to improve the adhesion between the positive electrode / solid electrolyte layer and the negative electrode / solid electrolyte layer interface in a state in which the positive electrode layer, the solid electrolyte layer and the negative electrode layer are laminated and the respective interfaces are in close contact with each other In a furnace, heat treatment was performed at 315 ° C. for 1 h, which is a temperature higher than the softening point of the oxide glass (A) and lower than the softening point of the oxide glass (B), to complete a power generating element. The side face of the obtained power generation element was masked, and this was incorporated into a CR2025 coin cell to complete an all solid state battery.
　[[比較例]]
　＜正極層＞
　正極活物質には、平均粒径が１０μｍのＬｉＣｏＯ2粉末を使用した。ＬｉＣｏＯ2粉末８ｇと、正極層内でのリチウムイオン伝導体として平均粒径が５μｍのＬＡＴＰを１．５ｇと、導電材としてケッチェンブラック０．５ｇを混合し、この混合粉末１０ｇにポリフッ化ビニリデンを１．０ｇ加え、これをＮＭＰに投入し、粘度を２０Ｐａ・ｓに調整した正極ペーストを得た。 [[Comparative example]]
<Positive electrode layer>
LiCoO 2 powder with an average particle diameter of 10 μm was used as the positive electrode active material. 8 g of LiCoO 2 powder, 1.5 g of LATP having an average particle diameter of 5 μm as a lithium ion conductor in the positive electrode layer, and 0.5 g of ketjen black as a conductive material are mixed, and 10 g of this mixed powder is polyvinylidene fluoride 1.0 g of this was added to NMP to obtain a positive electrode paste whose viscosity was adjusted to 20 Pa · s.
　この正極ペーストを厚さ２０μｍのアルミニウム箔に塗布、加熱成形および乾燥処理を施し、厚さ１２０μｍの正極シートを得た。これを直径１４ｍｍの円盤状に打ち抜き、正極層とした。 The positive electrode paste was applied to a 20 μm-thick aluminum foil, subjected to heating and drying treatment, and a 120 μm-thick positive electrode sheet was obtained. The resultant was punched into a disk shape having a diameter of 14 mm to form a positive electrode layer.
　＜負極層＞
　負極活物質には、平均粒径が１０μｍのＬｉ4Ｔｉ5Ｏ12粉末を使用した。Ｌｉ4Ｔｉ5Ｏ12粉末８ｇと、負極層内でのリチウムイオン伝導体として平均粒径が５μｍのＬＡＴＰを１．５ｇと、導電材としてケッチェンブラック０．５ｇを混合し、この混合粉末１０ｇにポリフッ化ビニリデンを０．５ｇ加え、これをＮＭＰに投入し、粘度を２０Ｐａ・ｓに調整した負極ペーストを得た。この負極ペーストを厚さ２０μｍの銅箔に塗布、加熱成形および乾燥処理を施し、厚さ１２０μｍの負極シートを得た。これを直径１４ｍｍの円盤状に打ち抜き、負極層とした。 <Negative electrode layer>
As the negative electrode active material, Li 4 Ti 5 O 12 powder having an average particle diameter of 10 μm was used. 8 g of Li 4 Ti 5 O 12 powder, 1.5 g of LATP having an average particle diameter of 5 μm as a lithium ion conductor in the negative electrode layer, and 0.5 g of ketjen black as a conductive material, and 10 g of this mixed powder Then, 0.5 g of polyvinylidene fluoride was added thereto, and this was charged into NMP to obtain a negative electrode paste whose viscosity was adjusted to 20 Pa · s. The negative electrode paste was applied to a copper foil of 20 μm in thickness, subjected to heat molding and drying treatment, to obtain a negative electrode sheet of 120 μm in thickness. The resultant was punched into a disk shape having a diameter of 14 mm to form a negative electrode layer.
　＜固体電解質層＞
　固体電解質には、平均粒径が５μｍのＬＡＴＰを使用した。ＬＡＴＰ粉末９．５ｇと、ポリフッ化ビニリデン０．５ｇを混合、これをＮＭＰに投入し、粘度を２０Ｐａ・ｓに調整した固体電解質ペーストを得た。この固体電解質ペーストを厚さ５０μｍのポリイミドシートに塗布し乾燥することで、厚さ１００μｍの固体電解質シートを得た。これを直径１５ｍｍの円盤状に打ち抜き、ポリイミドシートから分離して固体電解質層とした。 <Solid electrolyte layer>
For the solid electrolyte, LATP having an average particle size of 5 μm was used. A solid electrolyte paste having a viscosity adjusted to 20 Pa · s was obtained by mixing 9.5 g of LATP powder and 0.5 g of polyvinylidene fluoride and introducing this into NMP. This solid electrolyte paste was applied to a 50 μm thick polyimide sheet and dried to obtain a 100 μm thick solid electrolyte sheet. The resultant was punched into a disk shape having a diameter of 15 mm and separated from the polyimide sheet to form a solid electrolyte layer.
　＜電池化＞
　上記の正極層、固体電解質層、負極層を積層し、各々の界面を十分密着させた状態で、正極／固体電解質層、負極／固体電解質層界面の密着性を向上させることを目的として、電気炉中で、180℃、１ｈの熱処理をして発電素子を完成させた。得られた発電素子の側面をマスキングし、これをＣＲ２０２５型のコイン電池に組み込み比較例の全固体電池を完成させた。 <Battery>
In order to improve the adhesion between the positive electrode / solid electrolyte layer and the negative electrode / solid electrolyte layer interface in a state in which the positive electrode layer, the solid electrolyte layer and the negative electrode layer are laminated and the respective interfaces are in close contact with each other In the furnace, heat treatment was performed at 180 ° C. for 1 h to complete a power generation element. The side face of the obtained power generation element was masked, and this was incorporated into a CR2025 coin cell to complete an all solid state battery of a comparative example.
　（評価）
　実施例５および比較例で作製した電池について、初期容量測定、内部抵抗測定、および充放電サイクル試験を実施した。その結果、実施例５および比較例で作製した電池の初期容量に有意な差は認められなかった。一方、内部抵抗については、実施例５の方が比較例の内部抵抗よりも約４０％小さい値となり、実施例の全固体リチウムイオン二次電池の方が優れていることが明らかとなった。これは、正負極活物質粒子を、リチウムイオン伝導性を有する酸化物ガラスで被覆することで、電池反応において最も抵抗が高いと推定される、活物質粒子と固体電解質界面でのリチウムイオンの授受に伴う抵抗が大幅に低減できたこと、および、固体電解質層において、固体電解質粒子を、リチウムイオン伝導性を有する酸化物ガラス層で被覆することで、固体電解質層を形成した際にリチウムイオン伝導パスが発達したことによるものと考えられる。 (Evaluation)
Initial capacity measurement, internal resistance measurement, and charge and discharge cycle tests were performed on the batteries produced in Example 5 and Comparative Example. As a result, no significant difference was found in the initial capacities of the batteries produced in Example 5 and Comparative Example. On the other hand, regarding the internal resistance, the value of Example 5 is about 40% smaller than the internal resistance of the comparative example, and it is clear that the all solid lithium ion secondary battery of the example is superior. This is because the positive and negative electrode active material particles are coated with oxide glass having lithium ion conductivity, and it is estimated that the resistance is the highest in the battery reaction, and the transfer of lithium ions at the interface between the active material particles and the solid electrolyte In the solid electrolyte layer, by covering the solid electrolyte particles with an oxide glass layer having lithium ion conductivity, lithium ion conduction is formed when the solid electrolyte layer is formed. It is considered to be due to the development of the path.
　また、充放電サイクル試験においても、本実施例の全固体リチウムイオン二次電池の方が、大幅に寿命が向上する結果が得られた。これは、充放電の際にリチウムイオンの挿入・脱離により活物質の体積変化が生じても、酸化物ガラスへのリチウムイオンの挿入・脱離により、被覆層が膨張・収縮して界面の応力が緩和され、リチウムイオン伝導パスが維持されることで、性能の低下が抑制できたためと考えられる。 Also in the charge and discharge cycle test, the life of the all-solid-state lithium ion secondary battery of this example was significantly improved. This is because, even if the volume change of the active material occurs due to the insertion and desorption of lithium ions during charge and discharge, the coating layer expands and contracts due to the insertion and detachment of lithium ions in the oxide glass, and the interface It is considered that the decrease in performance could be suppressed by relieving the stress and maintaining the lithium ion conduction path.
　以上のように、本実施例の全固体リチウムイオン二次電池の方が比較例に比して優れており、優位性が確認された。 As described above, the all-solid-state lithium ion secondary battery of this example is superior to the comparative example and superiority is confirmed.
　なお、本実施例では電解質に固体電解質を使用した全固体リチウムイオン二次電池を例に挙げて記載したが、電解質に液体電解質を使用したリチウムイオン二次電池に適用してもよい。これは、通常、バインダを用いて正極あるいは負極を形成した際は、活物質表面のうち、バインダと接触している部分については、リチウムイオン伝導物質である電解質溶液と直接接触していないため、リチウムイオンの吸蔵・放出が起こりにくい。これに対し、本実施例のリチウムイオン電池は、正負極活物質に酸化物ガラスの被覆層を設けることにより、電極を形成する際、電極内にイオン伝導性を持たないバインダを含まない電極が作製できる。活物質の表面全体がリチウムイオン伝導体と接しているため、表面全面からのリチウムイオンの吸蔵・放出が容易に進行し、容量の増加や高レートでの充放電が可能となる。 In addition, although the all-solid-state lithium ion secondary battery which used the solid electrolyte for electrolyte as an example was described in the present Example, you may apply to the lithium ion secondary battery which uses a liquid electrolyte for electrolyte. This is usually because when the positive electrode or the negative electrode is formed using a binder, the portion of the surface of the active material in contact with the binder is not in direct contact with the electrolyte solution which is a lithium ion conductive material, It is difficult for lithium ion to occlude and release. On the other hand, in the lithium ion battery of the present embodiment, when the electrode is formed by providing the covering layer of oxide glass on the positive and negative electrode active materials, the electrode does not contain the binder having no ion conductivity in the electrode. It can be made. Since the entire surface of the active material is in contact with the lithium ion conductor, insertion and extraction of lithium ions from the entire surface easily proceeds, and capacity increase and charge / discharge at a high rate become possible.
　リチウムイオン二次電池に係り、電解質に液体を使用しない全固体リチウムイオン二次電池に利用可能である。 It relates to a lithium ion secondary battery, and can be used for an all solid lithium ion secondary battery that does not use a liquid as an electrolyte.
１；正極活物質、２；低融点ガラス被覆層、３；リチウムイオン、４；固体電解質層、５；正極、６；正極集電体、７；負極、８；負極集電体。 1; positive electrode active material, 2; low melting point glass coating layer, 3; lithium ion, 4; solid electrolyte layer, 5; positive electrode, 6; positive electrode current collector, 7; negative electrode, 8; negative electrode current collector.

Claims (16)

  1. 　リチウムイオンを吸蔵・放出する正極または負極活物質と、前記活物質を被覆する被覆層とを備えるリチウムイオン二次電池用の電極活物質粒子であって、
    　前記被覆層はリチウムイオン伝導性を有し、前記被覆層はリチウムイオンを吸蔵・放出して膨張・収縮する酸化物ガラスを有することを特徴とするリチウムイオン二次電池用電極活物質粒子。     An electrode active material particle for a lithium ion secondary battery, comprising: a positive electrode or a negative electrode active material that occludes and releases lithium ions; and a coating layer that covers the active material,
    The said coating layer has lithium ion conductivity, The said coating layer has an oxide glass which occludes, discharge | releases lithium ion and expand | swells / shrink | contracts, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  2. 　請求項１に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記酸化物ガラスの軟化点が５００℃以下であることを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 1, Comprising:
    The softening point of the said oxide glass is 500 degrees C or less, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  3. 　請求項１に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記酸化物ガラスは、バナジウムと、テルルおよびリンの少なくともいずれかを含むことを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 1, Comprising:
    The said oxide glass contains vanadium and at least one of tellurium and phosphorus, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  4. 　請求項３に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記酸化物ガラスは、鉄、マンガン、タングステン、モリブデン、バリウム、コバルトの少なくともいずれかを含むことを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 3, Comprising:
    The said oxide glass contains at least one of iron, manganese, tungsten, molybdenum, barium, and cobalt, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  5. 　請求項３または４に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記酸化物ガラスは、非晶質ガラスであることを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 3 or 4, Comprising:
    The said oxide glass is amorphous glass, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  6. 　請求項３または４に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記酸化物ガラスは、一部が結晶化した非晶質ガラスであることを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 3 or 4, Comprising:
    The said oxide glass is an amorphous glass which one part crystallized, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  7. 　請求項１に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記活物質に対する前記酸化物ガラスの割合は、体積換算で１体積％以上、３０体積％以下であることを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 1, Comprising:
    The ratio of the said oxide glass with respect to the said active material is 1 volume% or more and 30 volume% or less in terms of volume, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  8. 　請求項１に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記活物質は、酸化バナジウムを含む結晶化ガラスであることを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 1, Comprising:
    The said active material is crystallized glass containing a vanadium oxide, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  9. 　請求項１に記載のリチウムイオン二次電池用電極活物質粒子であって、
    　前記被覆層は導電粒子を含むことを特徴とするリチウムイオン二次電池用電極活物質粒子。     It is an electrode active material particle for lithium ion secondary batteries of Claim 1, Comprising:
    The said coating layer contains an electroconductive particle, The electrode active material particle for lithium ion secondary batteries characterized by the above-mentioned.
  10. 　請求項１ないし請求項９のいずれかに記載のリチウムイオン二次電池用電極活物質粒子を用いたリチウムイオン二次電池用電極。 The electrode for lithium ion secondary batteries using the electrode active material particle for lithium ion secondary batteries in any one of Claims 1-9.
  11. 　請求項１０に記載のリチウムイオン二次電池用電極であって、リチウムイオン伝導性を有する固体電解質粒子を備えることを特徴とするリチウムイオン二次電池用電極。 It is an electrode for lithium ion secondary batteries of Claim 10, Comprising: The solid electrolyte particle which has lithium ion conductivity is comprised, The electrode for lithium ion secondary batteries characterized by the above-mentioned.
  12. 　請求項１０に記載のリチウムイオン二次電池用電極であって、導電性粒子と、リチウムイオン伝導性を有する固体電解質粒子を備えることを特徴とするリチウムイオン二次電池用電極。 The electrode for a lithium ion secondary battery according to claim 10, comprising conductive particles and solid electrolyte particles having lithium ion conductivity.
  13. 　正極と、負極と、電解質とを備えるリチウムイオン二次電池であって、
    　前記正極及び負極は集電体と電極活物質とを有し、前記正極または負極の少なくともいずれかの電極活物質が、請求項１ないし９のいずれかに記載のリチウムイオン二次電池用電極活物質粒子を含むことを特徴とするリチウムイオン二次電池。     A lithium ion secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, comprising:
    The positive electrode and the negative electrode have a current collector and an electrode active material, and at least one electrode active material of the positive electrode or the negative electrode is an electrode active for a lithium ion secondary battery according to any one of claims 1 to 9. What is claimed is: 1. A lithium ion secondary battery comprising material particles.
  14. 　請求項１３に記載のリチウムイオン二次電池であって、
    前記電解質がリチウムイオン伝導性を有する固体電解質であって、正極及び負極の間に配置されていることを特徴とするリチウムイオン二次電池。     14. The lithium ion secondary battery according to claim 13, wherein
    The lithium ion secondary battery, wherein the electrolyte is a solid electrolyte having lithium ion conductivity, and is disposed between a positive electrode and a negative electrode.
  15. 　請求項１０ないし請求項１２のいずれかに記載されたリチウムイオン二次電池用電極の製造方法であって、前記酸化物ガラスの軟化点よりも高い温度で焼成する工程を有することを特徴とするリチウムイオン二次電池用電極の製造方法。 A method of producing an electrode for a lithium ion secondary battery according to any one of claims 10 to 12, characterized by comprising a step of firing at a temperature higher than the softening point of the oxide glass. The manufacturing method of the electrode for lithium ion secondary batteries.
  16. 　請求項１４に記載されたリチウムイオン二次電池の製造方法であって、前記酸化物ガラスの軟化点よりも高い温度で焼成し、前記正極または負極と、前記固体電解質とを一体化する工程を有することを特徴とするリチウムイオン二次電池の製造方法。 The method for producing a lithium ion secondary battery according to claim 14, wherein the step of firing the positive electrode or the negative electrode and the solid electrolyte is performed by firing at a temperature higher than the softening point of the oxide glass. The manufacturing method of the lithium ion secondary battery characterized by having.
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US11217785B2 (en) 2017-01-24 2022-01-04 Samsung Electronics Co., Ltd. Composite cathode active material and secondary battery including the same
US11532813B2 (en) 2020-02-20 2022-12-20 Samsung Electronics Co., Ltd. Composite cathode active material, preparation method thereof, cathode layer including the same, and all-solid secondary battery including the cathode layer

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