WO2022137359A1 - Batterie secondaire entièrement solide - Google Patents

Batterie secondaire entièrement solide Download PDF

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Publication number
WO2022137359A1
WO2022137359A1 PCT/JP2020/048034 JP2020048034W WO2022137359A1 WO 2022137359 A1 WO2022137359 A1 WO 2022137359A1 JP 2020048034 W JP2020048034 W JP 2020048034W WO 2022137359 A1 WO2022137359 A1 WO 2022137359A1
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Prior art keywords
solid
positive electrode
solid electrolyte
secondary battery
sintered plate
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PCT/JP2020/048034
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English (en)
Japanese (ja)
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一樹 前田
俊広 吉田
義政 小林
祐司 勝田
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日本碍子株式会社
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Priority to JP2022570832A priority Critical patent/JPWO2022137359A1/ja
Priority to PCT/JP2020/048034 priority patent/WO2022137359A1/fr
Publication of WO2022137359A1 publication Critical patent/WO2022137359A1/fr

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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
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy

Definitions

  • the present invention relates to an all-solid-state secondary battery, particularly an all-solid-state lithium-ion secondary battery.
  • a positive electrode active material layer for a lithium ion secondary battery it is obtained by kneading and molding a powder of a lithium composite oxide (typically, a lithium transition metal oxide) and an additive such as a binder or a conductive agent.
  • a powder of a lithium composite oxide typically, a lithium transition metal oxide
  • an additive such as a binder or a conductive agent.
  • Powder-dispersed positive electrodes are widely known. Since the powder-dispersed positive electrode contains a relatively large amount (for example, about 10% by weight) of a binder that does not contribute to the capacity, the packing density of the lithium composite oxide as the positive electrode active material is low. Therefore, there is a lot of room for improvement in the powder dispersion type positive electrode in terms of capacity and charge / discharge efficiency.
  • a liquid electrolyte (electrolyte solution) using a flammable organic solvent as a diluting solvent has been conventionally used as a medium for transferring ions.
  • problems such as leakage of the electrolytic solution, ignition, and explosion may occur.
  • solid-state batteries are being developed in which solid electrolytes are used instead of liquid electrolytes and all other elements are made of solids. ing. Since the electrolyte of such an all-solid-state battery is solid, there is no concern about ignition, liquid leakage does not occur, and problems such as deterioration of battery performance due to corrosion are unlikely to occur.
  • Patent Document 1 (WO2019 / 093222A1) contains an oriented positive electrode plate which is a lithium composite oxide sintered plate having a void ratio of 10 to 50%, Ti, and 0.4 V (against Li / Li +). )
  • an all-solid lithium battery including a negative electrode plate capable of inserting and removing lithium ions and a solid electrolyte having a melting point lower than the melting point or decomposition temperature of the oriented positive electrode board or the negative electrode plate is disclosed.
  • Various materials such as Li 2 SO 4 ) are disclosed.
  • Such a solid electrolyte can be permeated into the voids of the electrode plate as a melt, and strong interfacial contact can be realized. As a result, it is said that the battery resistance and the rate performance at the time of charging / discharging can be remarkably improved, and the yield of battery manufacturing can be significantly improved.
  • Patent Document 2 Li p (Ni x , Coy, Mn z ) O 2 (in the formula, 0.9 ⁇ p ⁇ 1.3, 0 ⁇ x ⁇ 0.8, 0 )
  • An oriented positive electrode plate having a layered rock salt structure having a basic composition represented by ⁇ y ⁇ 1, 0 ⁇ z ⁇ 0.7, x + y + z 1), a Li-La-Zr-O ceramic material and / or lithium phosphate.
  • an all-solid lithium battery comprising a solid electrolyte layer made of an oxynitride (LiPON) ceramic material and a negative electrode layer.
  • the positive electrode composition actually evaluated in Patent Document 2 has a molar ratio of Ni: Co: Mn of 5: 2: 3 or 1: 1: 1.
  • the present inventors have obtained the finding that among the above-mentioned low melting point solid electrolytes, the LiOH / Li 2 SO 4 system solid electrolytes such as 3 LiOH / Li 2 SO 4 exhibit high lithium ion conductivity.
  • a lithium composite oxide sintered plate having a Ni: Co: Mn molar ratio of 5: 2: 3 as conventionally used is used as a positive electrode, and a LiOH / Li 2 SO 4 system such as 3 LiOH / Li 2 SO 4 is used.
  • a cell was constructed with a solid electrolyte and the battery was operated, it was found that the discharge capacity was lower than the theoretical capacity assumed from the amount of active material.
  • the present inventors have recently constructed an all-solid-state secondary battery using a porous sintered plate of a lithium composite oxide containing Ni, Co and Mn in a molar ratio within a predetermined range as a positive electrode layer, thereby forming a discharge capacity. It was found that the charge / discharge characteristics such as the above can be significantly improved.
  • an object of the present invention is to provide an all-solid-state secondary battery having significantly improved charge / discharge characteristics such as discharge capacity.
  • Ni, Co and Mn 0.19 ⁇ Ni / (Ni + Co + Mn) ⁇ 0.41, 0.49 ⁇ Co / (Ni + Co + Mn) ⁇ 0.71 and 0.09 ⁇ Mn / (Ni + Co + Mn) ⁇ 0.11
  • An all-solid-state secondary battery is provided.
  • the all-solid-state secondary battery of the present invention includes a positive electrode layer, a negative electrode layer, and a solid electrolyte.
  • the positive electrode layer contains a porous sintered plate composed of a lithium composite oxide having a layered rock salt structure.
  • the negative electrode layer contains a porous sintered plate composed of a negative electrode active material.
  • the solid electrolyte is interposed between the positive electrode layer and the negative electrode layer as a separator layer, and is also filled in the pores of the porous sintered plate of the positive electrode layer and the negative electrode layer.
  • the lithium composite oxide contains Ni, Co and Mn in an amount of 0.19 ⁇ Ni / (Ni + Co + Mn) ⁇ 0.41, 0.49 ⁇ Co / (Ni + Co + Mn) ⁇ 0.71 and 0.09 ⁇ Mn. / (Ni + Co + Mn) ⁇ 0.11 is included in a molar ratio.
  • Ni, Co and Mn in an amount of 0.19 ⁇ Ni / (Ni + Co + Mn) ⁇ 0.41, 0.49 ⁇ Co / (Ni + Co + Mn) ⁇ 0.71 and 0.09 ⁇ Mn. / (Ni + Co + Mn) ⁇ 0.11 is included in a molar ratio.
  • an all-solid lithium battery impregnated with a low melting point solid electrolyte such as a LiOH / Li 2 SO 4 system solid electrolyte is known (see, for example, Patent Document 1), and the solid electrolyte is used as a melt in the electrode plate. Interfacial contact can be achieved by penetrating into the voids. As a result, it is possible to improve the battery resistance and the rate performance at the time of charging / discharging, and also improve the yield of battery manufacturing.
  • a lithium composite oxide sintered plate having a Ni: Co: Mn molar ratio of 5: 2: 3 as conventionally used is used as a positive electrode, and a LiOH / Li 2 SO 4 system such as 3 LiOH / Li 2 SO 4 is used.
  • a cell was constructed with a solid electrolyte and the battery was operated, it was found that the discharge capacity was lower than the theoretical capacity assumed from the amount of active material.
  • This problem can be conveniently solved by using a porous sintered plate of a lithium composite oxide containing Ni, Co and Mn in a molar ratio within the above range as a positive electrode layer.
  • the discharge capacity of the all-solid-state battery decreased due to the peeling and the suppression of the diffusion of Li ions.
  • the porous sintered plate composed of the lithium composite oxide in the above composition range of the present invention has a small expansion / contraction or volume change during charging / discharging, the above-mentioned problems are unlikely to occur, and as a result, the discharge capacity and the like are filled. It is considered to bring about a significant improvement in discharge characteristics.
  • the positive electrode layer contains a porous sintered plate composed of a lithium composite oxide having a layered rock salt structure as a positive electrode active material.
  • the porous sintered plate has a structure in which a plurality of primary particles composed of a lithium composite oxide having a layered rock salt structure are bonded.
  • This lithium composite oxide contains Ni, Co and Mn at 0.19 ⁇ Ni / (Ni + Co + Mn) ⁇ 0.41, 0.49 ⁇ Co / (Ni + Co + Mn) ⁇ 0.71 and 0.09 ⁇ Mn / ( A molar ratio that satisfies Ni + Co + Mn) ⁇ 0.11, more preferably 0.29 ⁇ Ni / (Ni + Co + Mn) ⁇ 0.31, 0.59 ⁇ Co / (Ni + Co + Mn) ⁇ 0.61, and 0.09 ⁇ Mn. / (Ni + Co + Mn) ⁇ 0.11 is included in a molar ratio. As described above, the composition (molar ratio) within the above range brings about a great improvement in charge / discharge characteristics such as discharge capacity.
  • Mn 3: 6: 1.
  • the NCM porous sintered plate has a ratio of the diffraction intensity I [003] due to the (003) plane to the diffraction intensity I [104] due to the (104) plane in the XRD profile measured by X-ray diffraction (XRD).
  • the degree of orientation I [003] / I [104] defined as is 1.2 to 3.6, preferably 1.2 to 3.5, and more preferably 1.2 to 3.0. , More preferably 1.2 to 2.6.
  • the volume change of the NCM porous sintered plate during charging and discharging is more likely to occur, the peeling between the sintered plate and the solid electrolyte is suppressed, and the discharge capacity and the like are more effectively filled.
  • the discharge characteristics can be improved.
  • a plane other than the crystal plane ((003) plane) where lithium ions are satisfactorily transferred in and out for example, a plane (101) or a plane (104). ) Side) and the other side (003) side.
  • each diffraction intensity of the (003) plane and the (104) plane by XRD is conveniently used as an index for calculating the degree of orientation.
  • the orientation degree I [003] / I [104] of the NCM powder which is a guideline for non-orientation, (
  • the anisotropy of expansion and contraction of the NCM primary particles constituting the NCM porous sintered plate is offset or alleviated by the randomness of the crystal orientation, so that the expansion and contraction of the entire NCM porous sintered plate is reduced.
  • the volume change of the NCM porous sintered plate during charging / discharging is less likely to occur, the peeling between the sintered plate and the solid electrolyte is suppressed, and the charging / discharging characteristics such as the discharge capacity are more effectively improved. it is conceivable that.
  • the porosity of the NCM porous sintered plate is 10 to 40%, preferably 15 to 38%, more preferably 18 to 36%, and even more preferably 20 to 33%. Within such a range, when the battery is manufactured, the pores can be sufficiently filled with the solid electrolyte, and the proportion of the positive electrode active material in the positive electrode increases, so that the high energy density of the battery can be achieved. It can be realized.
  • the "porosity” is the volume ratio of pores in a sintered plate. This porosity can be measured by image analysis of a cross-sectional SEM image of the sintered plate.
  • the polished cross section is observed with an SEM (scanning electron microscope) to obtain a cross section SEM image (for example, a magnification of 500 to 1000 times), and the obtained SEM is obtained.
  • SEM scanning electron microscope
  • the ratio (%) of the area filled with the resin to the total area of the part of the electrode active material and the part filled with the resin (the part that was originally a pore) is calculated and fired.
  • the pore ratio (%) of the knot may be calculated.
  • the porosity may be measured without embedding the sintered plate with resin.
  • the porosity of a sintered plate positive electrode plate taken out from an all-solid secondary battery in which the pores are filled with the solid electrolyte can be measured with the solid electrolyte still filled.
  • the average primary particle size of the NCM porous sintered plate is preferably 0.4 to 5.0 ⁇ m, more preferably 0.5 to 4.0 ⁇ m, still more preferably 0.6 to 3.0 ⁇ m, and particularly preferably 0. It is 0.8 to 2.5 ⁇ m, most preferably 1.0 to 2.2 ⁇ m. Within such a range, it is possible to more effectively improve the charge / discharge characteristics such as the discharge capacity. It is considered that this is because the primary particles are small as described above, so that the anisotropy of expansion and contraction of the lithium composite oxide primary particles due to charge and discharge is reduced.
  • the "average primary particle diameter" is an average value of the diameters of the primary particles contained in the sintered plate of the electrode.
  • the average primary particle diameters D 2 and D 3 are calculated, respectively.
  • the average values of the obtained average primary particle diameters D 1 , D 2 and D 3 are calculated and used as the average primary particle diameter D of the porous sintered plate.
  • the average primary particle size may be measured without embedding the sintered plate with resin.
  • the measurement of the average primary particle size of a sintered plate (positive electrode plate taken out from an all-solid secondary battery) in which the pores are filled with the solid electrolyte can be performed with the solid electrolyte still filled. ..
  • the average pore diameter of the NCM porous sintered plate is preferably 0.5 ⁇ m or more, more preferably 0.5 to 15.0 ⁇ m, still more preferably 0.7 to 15.0 ⁇ m, and particularly preferably 0.8 to 10.0 ⁇ m. Most preferably, it is 0.9 to 8.0 ⁇ m. Within such a range, the number of solid electrolyte portions (solid electrolyte portions located at a distance from the interface) that are less susceptible to deterioration due to side reactions between the solid electrolyte and the sintered plate increases.
  • the "average pore diameter” is an average value of the diameters of pores contained in the sintered plate of the electrode. Such “diameter” is typically the length of a line segment (Martin diameter) that divides the projected area of the pore into two equal parts.
  • the "mean value” is preferably calculated on the basis of the number of pieces. This average pore diameter can be measured by image analysis of a cross-sectional SEM image of the sintered plate.
  • the SEM image obtained by the above-mentioned porosity measurement is analyzed, and the portion of the sintered plate that is filled with the electrode active material and the portion filled with the resin (the portion that was originally the pores) is separated and then filled with the resin.
  • the maximum Martin diameter of each region may be obtained in the region of the portion, and the average value thereof may be used as the average pore diameter of the sintered plate. If the measurement can be performed with a desired accuracy, the average pore diameter may be measured without embedding the sintered plate with resin. For example, the average pore diameter of a sintered plate (positive electrode plate taken out from an all-solid-state secondary battery) in which the pores are filled with the solid electrolyte can be measured with the solid electrolyte still filled.
  • the thickness of the NCM porous sintered plate is preferably 30 to 200 ⁇ m, more preferably 50 to 200 ⁇ m, and even more preferably 80 to 200 ⁇ m from the viewpoint of improving the energy density of the battery.
  • Various characteristics such as porosity, average primary particle size, and average pore size of the NCM porous sintered plate control the particle size of the NCM raw material powder, or a mixed powder of two or more types of NCM raw material powder having different particle size distributions. It can be appropriately controlled by using it or adjusting the firing conditions.
  • the negative electrode layer includes a porous sintered plate made of a negative electrode active material.
  • a negative electrode active material generally used for a lithium secondary battery can be used.
  • Examples of such general negative electrode active materials include carbon-based materials, metals or metalloids such as Li, In, Al, Sn, Sb, Bi, Si, or alloys containing any of these. ..
  • an oxide-based negative electrode active material may be used.
  • a particularly preferable negative electrode active material contains a material capable of inserting and removing lithium ions at 0.4 V (vs. Li / Li + ) or higher, and preferably contains Ti.
  • the negative electrode active material satisfying such conditions is preferably an oxide containing at least Ti, that is, a titanium-containing oxide.
  • Preferred examples of such a negative electrode active material include lithium titanate Li 4 Ti 5 O 12 (hereinafter, may be referred to as LTO), niobium titanium composite oxide Nb 2 TIO 7 , and titanium oxide TIO 2 .
  • LTO and Nb 2 TiO 7 are preferable, and LTO is more preferable.
  • LTO is typically known to have a spinel-type structure, other structures may be adopted during charging / discharging. For example, LTO reacts in a two-phase coexistence of Li 4 Ti 5 O 12 (spinel structure) and Li 7 Ti 5 O 12 (rock salt structure) during charging and discharging. Therefore, LTO is not limited to the spinel structure.
  • the porous sintered plate made of the negative electrode active material does not need to contain an electron conduction aid or a binder, the energy density of the negative electrode can be increased.
  • the pores of the porous sintered plate are filled with a solid electrolyte.
  • the porosity of the negative electrode active material or its sintered plate is preferably 20 to 45%, more preferably 20 to 40%, and even more preferably 25 to 35%. If the porosity is within such a range, the pores in the negative electrode active material can be sufficiently filled with the solid electrolyte, and the proportion of the negative electrode active material in the negative electrode increases, so that the energy density of the battery is high. Can be realized.
  • the thickness of the negative electrode active material or its sintered plate is preferably 40 to 270 ⁇ m, more preferably 65 to 270 ⁇ m, still more preferably 100 to 270 ⁇ m, and particularly preferably 107 to 270 ⁇ m from the viewpoint of improving the energy density of the battery. be.
  • the solid electrolyte is not particularly limited as long as it can be applied to an all-solid-state secondary battery, particularly an all-solid-state lithium secondary battery.
  • examples thereof include garnet-based ceramic materials, nitride-based ceramic materials, perovskite-based ceramic materials, phosphoric acid-based ceramic materials, sulfide-based ceramic materials, borosilicate-based ceramic materials, lithium-halide-based materials, and polymer-based materials. Be done.
  • garnet-based ceramic materials include Li-La-Zr-O-based materials (specifically, Li 7 La 3 Zr 2 O 12 and the like) and Li-La-Ta-O-based materials (specifically, Li-La-Ta-O-based materials).
  • Li 7 La 3 Ta 2 O 12 etc. An example of a nitride - based ceramic material is Li 3N.
  • examples of perovskite-based ceramic materials include Li-La-Zr-O-based materials (specifically, LiLa 1-x Ti x O 3 (0.04 ⁇ x ⁇ 0.14) and the like).
  • Examples of phosphoric acid-based ceramic materials include lithium phosphate, nitrogen-substituted lithium phosphate (LiPON), Li-Al-Ti-PO, Li-Al-Ge-PO, and Li-Al-Ti-.
  • Examples thereof include Si—P—O (specifically, Li 1 + x + y Al x Ti 2-x Si y P 3-y O 12 (0 ⁇ x ⁇ 0.4, 0 ⁇ y ⁇ 0.6), etc.).
  • Examples of sulfide-based ceramic materials include LiOH-Li 2 SO 4 and Li 3 BO 3 -Li 2 SO 4 -Li 2 CO 3 .
  • Examples of the borosilicate ceramic material include Li 2O -B 2O 3 -SiO 2 .
  • Examples of lithium-halide materials include Li 3 OX (in the formula, X is Cl and / or Br), Li 2 (OH) 1-a Fa Cl (in the formula, 0 ⁇ a ⁇ 0. 3) and Li 2 OHX (where X is Cl and / or Br).
  • a preferred solid electrolyte is a LiOH / Li 2 SO 4 system solid electrolyte.
  • the LiOH / Li 2 SO 4 system solid electrolyte contains a solid electrolyte identified as 3 LiOH / Li 2 SO 4 by X-ray diffraction.
  • This preferred solid electrolyte contains 3LiOH ⁇ Li 2 SO 4 as the main phase. Whether or not 3LiOH / Li 2 SO 4 is contained in the solid electrolyte can be confirmed by identifying the X-ray diffraction pattern using 032-0598 of the ICDD database.
  • 3LiOH / Li 2 SO 4 refers to a crystal structure that can be regarded as the same as 3LiOH / Li 2 SO 4 , and the crystal composition does not necessarily have to be the same as 3LiOH / Li 2 SO 4 .
  • the solid electrolyte contains a dopant such as boron (for example, 3LiOH / Li 2 SO 4 in which boron is dissolved and the X-ray diffraction peak is shifted to the high angle side), the crystal structure is 3LiOH / Li 2 SO. As long as it can be regarded as the same as 4 , it is referred to herein as 3LiOH ⁇ Li 2 SO 4 .
  • the solid electrolyte used in the present invention also allows the inclusion of unavoidable impurities.
  • the LiOH / Li 2 SO 4 system solid electrolyte may contain a different phase in addition to the main phase of 3LiOH / Li 2 SO 4 .
  • the heterogeneous phase may contain a plurality of elements selected from Li, O, H, S and B, or may consist only of a plurality of elements selected from Li, O, H, S and B. May be.
  • Examples of the heterogeneous phase include LiOH, Li 2 SO 4 and / or Li 3 BO 3 derived from the raw material. Regarding these heterogeneous phases, it is considered that unreacted raw materials remained when forming 3LiOH / Li2SO4 , but since they do not contribute to lithium ion conduction , the amount is smaller except for Li3BO3 . desirable.
  • the heterogeneous phase containing boron such as Li 3 BO 3
  • the heterogeneous phase containing boron may be contained in a desired amount because it can contribute to the improvement of the lithium ion conductivity maintenance after holding at a high temperature for a long time.
  • the solid electrolyte may be composed of a single phase of 3LiOH / Li 2 SO 4 in which boron is dissolved.
  • the LiOH / Li 2 SO 4 system solid electrolyte (particularly 3 LiOH / Li 2 SO 4 ) preferably further contains boron.
  • boron By further containing boron in the solid electrolyte identified as 3LiOH / Li 2SO 4 , it is possible to significantly suppress the decrease in lithium ion conductivity even after holding at a high temperature for a long time. Boron is presumed to be incorporated into one of the sites of the crystal structure of 3LiOH / Li2SO4 and improve the stability of the crystal structure with respect to temperature.
  • the molar ratio (B / S) of boron B to sulfur S contained in the solid electrolyte is preferably more than 0.002 and less than 1.0, more preferably 0.003 or more and 0.9 or less, still more preferably. It is 0.005 or more and 0.8 or less.
  • B / S is within the above range, it is possible to improve the maintenance rate of lithium ion conductivity. Further, when the B / S is within the above range, the content of the unreacted heterogeneous phase containing boron is low, so that the absolute value of the lithium ion conductivity can be increased.
  • the LiOH / Li 2 SO 4 system solid electrolyte may be a green compact of a powder obtained by crushing a melt-solidified body, but a melt-solidified body (that is, one solidified after being heated and melted) is preferable.
  • the LiOH / Li 2 SO 4 system solid electrolyte is filled in the pores of the porous sintered plate of the positive electrode layer and the negative electrode layer by melting, but the remaining portion is a separator layer (separator layer) between the positive electrode layer and the negative electrode layer. Intervenes as a solid electrolyte layer).
  • the thickness of the separator layer (excluding the portion that has entered the pores of the positive electrode layer and the negative electrode layer) is preferably 1 to 500 ⁇ m, more preferably 3 to 50 ⁇ m, and more preferably 3 to 50 ⁇ m from the viewpoint of charge / discharge rate characteristics and the insulating property of the solid electrolyte. It is preferably 5 to 40 ⁇ m.
  • the intermediate layer is provided at the interface between at least one of the positive electrode active material and the negative electrode active material and the solid electrolyte.
  • the discharge capacity can be further improved (compared to the one without the intermediate layer).
  • the detailed mechanism for improving the discharge capacity is not clear, it is speculated that the presence of the intermediate layer may suppress the deterioration of the solid electrolyte due to the reaction between the solid electrolyte and the active material.
  • the intermediate layer is more preferable that the intermediate layer is present at the interface between the positive electrode active material and the solid electrolyte, but the intermediate layer may be present at the interface between the negative electrode active material and the solid electrolyte.
  • the intermediate layer may be present at both the interface between the positive electrode active material and the solid electrolyte and the interface between the negative electrode active material and the solid electrolyte.
  • the thickness of the intermediate layer is not particularly limited as long as the desired effect of improving the discharge capacity can be obtained, but is preferably 0.001 to 1 ⁇ m, more preferably 0.005 to 0.2 ⁇ m, and further preferably 0.01 to 0.1 ⁇ m. Is.
  • the intermediate layer is a lithium composite oxide containing Li and at least one selected from the group consisting of Ti, La, Zr, Al, W, Nb, Sn, Ce, Mn, Y, and Ta, and / or Y. It is preferably composed of an oxide of ( typically Y2O3 ).
  • Preferred examples of such lithium composite oxides are Li and Ti oxides (typically Li 2 TiO 3 ), Li, La and Zr or Li, La, Zr and Al oxides (typically). Is an oxide of Li 7-3 x Al x La 3 Zr 2 O 12 ( 0 ⁇ x ⁇ 0.4, more typically 0.02 ⁇ x ⁇ 0.4)), Li, La and Ti (typical).
  • Li 0.33 La 0.55 TiO 3 Li and W oxides (typically Li 2 WO 4 ), Li and Al oxides (typically LiAlO 2 ), Li and Nb.
  • Oxides typically LiNbO 3 or LiNb 3O 8
  • Li and Sn oxides typically LiSnO 3
  • Li and Ce oxides typically Li 8 CeO 6
  • Li, La and Nb oxides typically Li 5 La 3 Nb 2 O 12
  • Li and Mn oxides typically LiMnO 2
  • Li and Y oxides typically LiYO 2 ).
  • Li and Ta oxides typically LiTaO 3
  • Li and Ti oxides typically Li 2 TiO 3
  • Li, La, Oxides of Zr and Al typically Li 6.7 Al 0.1 La 3 Zr 2 O 12
  • oxides of Li, La and Ti typically Li 0.33 La 0.55 TIO). 3
  • a solution is prepared by mixing a metal alkoxide of one or more metal elements constituting the intermediate layer and a metal salt such as nitrate with alcohol such as ethanol or water at a predetermined molar ratio to prepare an electrode active material. This can be done by immersing (preferably a sintered plate or particles) in this solution, then taking it out and allowing it to stand in the air to hydrolyze the alkoxide or dry the solvent.
  • a sintered plate it is preferable to infiltrate the inside of the solution by dipping it in a solution under reduced pressure, and it is preferable to repeat the work from the dipping to standing in the air a plurality of times (for example, 1 to 20 times). preferable.
  • the electrode active material preferably sintered plate or particles
  • All-solid-state secondary battery is, for example, i) forming an intermediate layer and a current collector (with an intermediate layer and a current collector formed as needed) and a positive electrode (with an intermediate layer and a current collector formed as needed). This can be done by preparing the negative electrode and ii) sandwiching a solid electrolyte between the positive electrode and the negative electrode and applying pressure, heating, or the like to integrate the positive electrode, the solid electrolyte, and the negative electrode.
  • the positive electrode, the solid electrolyte, and the negative electrode may be bonded by other methods.
  • a method of placing a solid electrolyte molded body or powder on one of the electrodes a method of screen-printing a paste of the solid electrolyte powder on the electrode.
  • Examples thereof include a method of colliding and solidifying a solid electrolyte powder by an aerosol disposition method or the like using an electrode as a substrate, and a method of depositing a solid electrolyte powder on an electrode by an electrophoresis method to form a film.
  • a lithium composite oxide having a layered rock salt structure containing Li, Ni, Co and Mn such as (Ni 0.3 Co 0.6 Mn 0.1 ) O 2 is abbreviated as "NCM”.
  • Li 4 Ti 5 O 12 shall be abbreviated as "LTO”.
  • NCM raw material powders 1 to 6 for producing a positive electrode plate were prepared.
  • Table 1 shows a summary of the methods for producing these raw material powders.
  • NCM raw material powder 1 Preparation of NCM raw material powder 1
  • Commercially available (Ni 0.5 Co 0.2 Mn 0.3 ) (OH) 2 powder (average particle size 9 to 10 ⁇ m) and Li weighed so that the molar ratio of Li / (Ni + Co + Mn) is 1.15.
  • 2 CO 3 powder (average particle size 3 ⁇ m) was mixed. The obtained mixed powder was held at 750 ° C. for 10 hours, the volume standard D50 particle size was adjusted to about 5.5 ⁇ m by wet pulverization with a ball mill, and then dried to obtain NCM raw material powder 1.
  • NCM raw material powder 2 Preparation of NCM raw material powder 2
  • Commercially available (Ni 0.3 Co 0.6 Mn 0.1 ) (OH) 2 powder (average particle size 7 to 8 ⁇ m) and Li weighed so that the molar ratio of Li / (Ni + Co + Mn) is 1.15.
  • 2 CO 3 powder (average particle size 3 ⁇ m) was mixed. The obtained mixed powder was held at 850 ° C. for 10 hours to obtain NCM raw material powder 2. The volume-based D50 particle size of this powder was about 6.5 ⁇ m.
  • NCM raw material powder 3 The volume-based D50 particle size of the NCM raw material powder 2 was adjusted to about 4.3 ⁇ m by wet pulverization with a ball mill, and then dried to obtain the NCM raw material powder 3.
  • NCM raw material powder 4 Preparation of NCM raw material powder 4
  • Commercially available (Ni 0.2 Co 0.7 Mn 0.1 ) (OH) 2 powder (average particle size 7 to 8 ⁇ m) and Li weighed so that the molar ratio of Li / (Ni + Co + Mn) is 1.15.
  • 2 CO 3 powder (average particle size 3 ⁇ m) was mixed. The obtained mixed powder was held at 850 ° C. for 10 hours, the volume standard D50 particle size was adjusted to about 4.5 ⁇ m by wet pulverization with a ball mill, and then dried to obtain NCM raw material powder 4.
  • NCM raw material powder 5 Preparation of NCM raw material powder 5
  • 2 CO 3 powder average particle size 3 ⁇ m was mixed. The obtained mixed powder was held at 850 ° C. for 10 hours, the volume standard D50 particle size was adjusted to about 4.6 ⁇ m by wet pulverization with a ball mill, and then dried to obtain NCM raw material powder 5.
  • NCM raw material powder 6 Preparation of NCM raw material powder 6
  • 2 CO 3 powder average particle size 3 ⁇ m was mixed. The obtained mixed powder was held at 750 ° C. for 10 hours, the volume standard D50 particle size was adjusted to about 0.4 ⁇ m by wet pulverization with a ball mill, and then dried to obtain NCM raw material powder 6.
  • Example 1 (comparison) (1) Preparation of positive electrode plate (1a) Preparation of NCM green sheet First, the NCM raw material powder 1 shown in Table 1 was prepared. This NCM raw material powder 1 was mixed with a solvent for tape molding, a binder, a plasticizer, and a dispersant. After adjusting the viscosity of the obtained paste, an NCM green sheet was produced by molding it into a sheet on a PET (polyethylene terephthalate) film. The thickness of the NCM green sheet was adjusted so that the thickness after firing was 100 ⁇ m.
  • NCM Sintered Plate The NCM green sheet peeled off from the PET film was punched out into a circle with a diameter of 11 mm and placed in a firing sheath. Baking was performed by raising the temperature to 920 ° C. at a heating rate of 200 ° C./h and holding it for 10 hours. The thickness of the obtained sintered plate was about 100 ⁇ m as observed by SEM. An Au film (thickness 100 nm) was formed as a current collector layer on one side of this NCM sintered plate by sputtering. In this way, a positive electrode plate was obtained.
  • the thickness and porosity (% by volume) of each of the LTO sintered plates in the state were measured as follows. First, the positive electrode plate (or the negative electrode plate) was embedded with resin, and then the cross section was polished by ion milling, and then the polished cross section was observed by SEM to obtain a cross section SEM image. The thickness was calculated from this SEM image.
  • the SEM images for porosity measurement were images with a magnification of 1000 times and a magnification of 500 times.
  • the obtained image is binarized using image analysis software (Image-Pro Premier manufactured by Media Cybernetics), and the positive electrode active material (or negative electrode active material) in the positive electrode plate (or negative electrode plate) is subjected to binarization treatment.
  • Porosity of the positive electrode plate (or negative electrode plate) by calculating the ratio (%) of the area filled with resin to the total area of the part filled with resin and the part filled with resin (the part that was originally pores). It was set to (%).
  • the threshold value for binarization was set using Otsu's binarization as a discriminant analysis method.
  • the porosity of the positive electrode plate is as shown in Table 2, and the porosity of the negative electrode plate was 38%.
  • the average pore diameter was measured as follows. Image analysis software (Image-Pro Premier manufactured by Media Cybernetics) is used to perform a binarization process, and the positive electrode plate (or negative electrode plate) is filled with a portion of the positive electrode active material (or negative electrode active material) and a resin. The part (the part that was originally a pore) was cut out. Then, in the region of the portion filled with the resin, the maximum Martin diameter of each region was obtained, and the average value thereof was taken as the average pore diameter ( ⁇ m) of the positive electrode plate (or the negative electrode plate).
  • the average pore diameter of the positive electrode plate is as shown in Table 2, and the average pore diameter of the negative electrode plate was 2.1 ⁇ m.
  • the same operation as described above was performed twice by changing the position each time, and the average primary particle diameters D 2 and D 3 were calculated, respectively.
  • the average values of the obtained average primary particle diameters D 1 , D 2 and D 3 were calculated and used as the average primary particle diameter D of the positive electrode plate.
  • the average primary particle diameter D of the positive electrode plate was as shown in Table 2.
  • Example 2 In the production of the positive electrode plate of (1) above, the positive electrode plate and the battery were produced in the same manner as in Example 1 except that the NCM raw material powder 3 shown in Table 1 was used instead of the NCM raw material powder 1. Evaluation was performed.
  • Example 3 In the production of the positive electrode plate of (1) above, the positive electrode plate and the battery were produced in the same manner as in Example 1 except that the NCM raw material powder 4 shown in Table 1 was used instead of the NCM raw material powder 1. Evaluation was performed.
  • Example 4 In the production of the positive electrode plate of (1) above, the positive electrode plate and the battery were produced in the same manner as in Example 1 except that the NCM raw material powder 5 shown in Table 1 was used instead of the NCM raw material powder 1. Evaluation was performed.
  • Example 5 In the production of the positive electrode plate of (1) above, the positive electrode plate and the battery were produced in the same manner as in Example 1 except that the NCM raw material powder 6 shown in Table 1 was used instead of the NCM raw material powder 1. Evaluation was performed.
  • Example 6 In the production of the positive electrode plate of (1) above, instead of 1) NCM raw material powder 1, NCM mixed powder A containing NCM raw material powders 2 and 6 shown in Table 1 in a blending ratio (weight ratio) of 90:10 is used. A positive electrode plate and a battery were produced in the same manner as in Example 1 except that they were used and 2) the firing temperature was set to 950 ° C., and various evaluations were performed.
  • Example 7 In the production of the positive electrode plate of (1) above, instead of 1) NCM raw material powder 1, NCM mixed powder A containing NCM raw material powders 2 and 6 shown in Table 1 in a blending ratio (weight ratio) of 90:10 is used. A positive electrode plate and a battery were produced in the same manner as in Example 1 except that they were used and 2) the firing temperature was set to 900 ° C., and various evaluations were performed.
  • Example 8 In the preparation of the positive electrode plate of (1) above, instead of 1) NCM raw material powder 1, NCM mixed powder B containing NCM raw material powders 2 and 6 shown in Table 1 at a blending ratio (weight ratio) of 70:30 is used. A positive electrode plate and a battery were produced in the same manner as in Example 1 except that they were used and 2) the firing temperature was set to 950 ° C., and various evaluations were performed.
  • Example 9 In the production of the positive electrode plate of (1) above, instead of 1) NCM raw material powder 1, NCM mixed powder C containing NCM raw material powders 2 and 6 shown in Table 1 in a blending ratio (weight ratio) of 95: 5 is used. A positive electrode plate and a battery were prepared in the same manner as in Example 1 except that they were used and 2) the firing temperature was set to 970 ° C., and various evaluations were performed.
  • Results Table 2 shows the specifications of the positive electrode plates produced in each example and the evaluation results of the cells. As described above, the charge / discharge characteristics were compared under the same rate conditions, the discharge capacity measured in Example 1 (comparison) was regarded as 100, and the relative value with respect to this was calculated and shown in Table 2.

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Abstract

L'invention concerne une batterie secondaire entièrement solide dans laquelle des caractéristiques de charge/décharge telles que la capacité de décharge sont considérablement améliorées. Cette batterie secondaire entièrement solide comprend : une couche d'électrode positive comprenant une plaque frittée poreuse configurée à partir d'un oxyde composite de lithium ayant une structure de sel rocheuse en couches ; une couche d'électrode négative comprenant une plaque frittée poreuse configurée à partir d'un matériau actif d'électrode négative ; et un électrolyte solide qui est interposé en tant que couche de séparateur entre la couche d'électrode positive et la couche d'électrode négative, l'électrolyte solide remplissant également les pores des plaques frittées poreuses dans la couche d'électrode positive et la couche d'électrode négative. L'oxyde composite de lithium contient du Ni, du Co et du Mn à un rapport molaire qui satisfait 0,19 ≤ Ni/(Ni + Co + Mn) ≤ 0,41, 0,49 ≤ Co/(Ni + Co + Mn) ≤ 0,71 et 0,09 ≤ Mn/(Ni + Co + Mn) ≤ 0,11.
PCT/JP2020/048034 2020-12-22 2020-12-22 Batterie secondaire entièrement solide WO2022137359A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011076797A (ja) * 2009-09-29 2011-04-14 Sanyo Electric Co Ltd 非水電解質二次電池
WO2019093222A1 (fr) * 2017-11-10 2019-05-16 日本碍子株式会社 Batterie au lithium entièrement solide et son procédé de fabrication
JP2020536367A (ja) * 2017-10-06 2020-12-10 ビーエーエスエフ ソシエタス・ヨーロピアＢａｓｆ Ｓｅ 電極活物質、その製造及び使用方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011076797A (ja) * 2009-09-29 2011-04-14 Sanyo Electric Co Ltd 非水電解質二次電池
JP2020536367A (ja) * 2017-10-06 2020-12-10 ビーエーエスエフ ソシエタス・ヨーロピアＢａｓｆ Ｓｅ 電極活物質、その製造及び使用方法
WO2019093222A1 (fr) * 2017-11-10 2019-05-16 日本碍子株式会社 Batterie au lithium entièrement solide et son procédé de fabrication

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