JP2017191646A - Composite laminate, lithium battery, and method for manufacturing composite laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further increase the bondability between a solid electrolyte and an active material to further improve a battery performance.SOLUTION: A composite laminate according to the present invention comprises: a first layer including a solid electrolyte; a second layer including a flux including Li and B, and an active material consisting of a composite compound including Li and a transition metal; and an interface part located between the active material and the solid electrolyte, and including Li, B and Si.SELECTED DRAWING: None

Description

  The present invention relates to a composite laminate, a lithium battery, and a method for producing a composite laminate.

  Conventionally, as an all solid lithium secondary battery, a garnet-type ion conductive oxide containing Li, La, and Zr has been proposed as a solid electrolyte (see, for example, Patent Document 1). In this solid electrolyte, by replacing Zr with Nb, the chemical stability is excellent, the potential window is wide, and the lithium ion conductivity is higher.

JP 2010-272344 A

  By the way, when an oxide solid electrolyte as in Patent Document 1 is used as a lithium secondary battery, an active material layer is formed on the surface thereof. At this time, for example, the lithium ion conductivity at the solid-solid interface between the solid electrolyte layer and the active material layer is not sufficient, which may adversely affect the battery performance. For example, in the case where the battery needs to be discharged with a large current, such as a battery for an electric vehicle, it is desired to further increase the battery capacity, for example, by improving the bondability between the solid electrolyte layer and the active material layer. It was.

  The present invention has been made in view of such a problem, and a composite laminate, a lithium battery, and a battery capable of further improving battery performance by further improving the bondability between the solid electrolyte layer and the active material layer, and The main object is to provide a method for producing a composite laminate.

As a result of diligent research to achieve the above-described object, the present inventors have found that when SiO ₂ is added to the flux for fixing the active material particles (composite oxide particles), the solid electrolyte layer and the active material layer are not separated. The present inventors have found that the battery performance can be further improved by further improving the bondability of the present invention, and the present invention has been completed.

That is, the composite laminate of the present invention is
A first layer comprising a solid electrolyte;
A second layer containing an active material of a composite compound containing Li and a transition metal, and a flux containing Li and B;
An interface between Li and B and Si that exists between the active material and the solid electrolyte;
It is equipped with.

  The lithium battery of the present invention comprises the above composite laminate.

The method for producing the composite laminate of the present invention comprises:
A laminating step in which a second layer containing an active material of a composite compound containing Li and a transition metal and a flux containing Li, B, and Si is formed on the surface of the first layer containing a solid electrolyte to form a laminate;
A firing step of firing the laminate;
Is included.

  In the present invention, the battery performance can be further improved by further improving the bondability between the solid electrolyte layer and the active material layer. The reason why such an effect is obtained is presumed as follows. For example, the interface portion generated between the active material and the solid electrolyte contains Li, B, Si, and O, and is presumed to have low Li ion conductivity. On the other hand, it is surmised that this interface part has improved the contact property between the active material and the solid electrolyte. As a result, the ionic conductivity between the active material and the solid electrolyte is improved, and the battery capacity is improved. It is inferred that the battery performance can be further improved, such as improvement.

FIG. 2 is an explanatory diagram showing an example of the structure of an all-solid-type lithium battery 10. Explanatory drawing of the favorable composition range of a flux. The SEM photograph of the cross section of a composite laminated body. Graph showing the relationship between the discharge current I / C and the discharge capacity Q / Q _0. Graph showing the relationship between the composition of the flux and the discharge capacity Q / Q _0.

  The composite laminate of the present invention includes a first layer, a second layer, and an interface portion. The first layer includes a solid electrolyte. The second layer includes a composite compound active material containing Li and a transition metal, and a flux containing Li and B. The interface portion exists between the active material and the solid electrolyte and includes Li, B, and Si.

The solid electrolyte contained in the first layer is not particularly limited, but is preferably an oxide-based inorganic solid electrolyte, and examples thereof include a garnet-type oxide having lithium ion conductivity. The garnet-type oxide contains Li, La, and Zr, and is an element different from La, at least one element A among alkaline earth metal and lanthanoid elements, an element different from Zr, and oxygen and 6 It is good also as a thing containing at least 1 or more types of element T among the transition elements which can take a coordination, and the typical elements which belong to 12th group-15th group. More specifically, the garnet-type oxide has a basic composition Li _{7 + XY} La _3−X A _X Zr _2−Y T _Y O ₁₂ (wherein the element A is derived from Ba, Sr, Ca, Mg and Y). And at least one element selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Al, Si, Ga, and Ge. It is more preferable that it is an element, and 0 <X ≦ 1, 0 ≦ Y ≦ 1, and X <Y. The element A is preferably, for example, Sr or Ca. If Sr is contained, the melting energy is lowered, and the firing energy can be further reduced, for example, the firing temperature is lowered. If Ca is contained, lithium ion conductivity can be further improved. The element T is preferably Nb. When Nb is included, lithium ion conductivity can be further increased. In this basic composition formula, the garnet-type oxide more preferably satisfies 0.05 ≦ X ≦ 0.1.

The first layer containing a garnet-type oxide preferably has an electric conductivity (lithium ion conductivity, 25 ° C.) of 0.4 × 10 ⁻⁴ (S / cm) or more, and is 1.0 × 10 ^−4. (S / cm) or more is more preferable, and 1.5 × 10 ⁻⁴ (S / cm) or more is further preferable. This lithium ion conductivity can be changed as appropriate by adjusting the addition ratio (X, Y) of the flux, element A and element T, and the firing temperature.

  The garnet-type oxide is preferably baked at 1100 ° C. or lower, more preferably baked at 1050 ° C. or lower, and further preferably baked at 1000 ° C. or lower. In firing at 1100 ° C. or lower, the firing energy can be further reduced. From the viewpoint of forming a garnet structure, the garnet oxide is preferably fired at 800 ° C. or higher.

Here, the garnet-type oxide is only required to have mainly a garnet-type structure. For example, the garnet-type oxide includes a part of the structure other than the garnet-type structure or the peak position of X-ray diffraction is shifted. It may include a structure that is distorted when viewed from the viewpoint. In addition, as shown by the composition formula, the first layer may partially include other elements and structures. The “basic composition” means that the element A and the element T may each contain a main component element and one or more subcomponent elements. The details of the garnet-type lithium ion conductive oxide represented by the basic composition Li _{7 + XY} La _3−X A _X Zr _2−Y T _Y O ₁₂ are described in, for example, Japanese Patent Application Laid-Open No. 2010-202499. Has been.

Examples of solid electrolytes include glass ceramics, Li nitrides, halides, and oxyacid salts. Specifically, Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ , Li _{1 + X} Ti ₂ Si _X P _{3 -X} O ₁₂ .AlPO ₄ , Li _3.25 Ge _0.25 P _0.25 S ₄ , Li ₄ SiO ₄ , Li _{4 SiO 4 -LiI-LiOH, xLi} 3 PO 4 - (1-x) Li 4 SiO 4, Li 2 SiS 3, Li 3 PO 4 -Li 2 S-SiS 2, and the like phosphorus sulfide compound.

The composite compound contained in the second layer may contain, for example, one or more of Fe, Co, Ni, Mn, and Ti, and may further contain Li. For example, the composite compound includes an oxide containing lithium and a transition metal element, a phosphate compound containing lithium and a transition metal element, and the like. The composite oxide is preferably one represented by a basic composition LiCo _a Ni _b Mn _c O ₂ (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, a + b + c = 1). In this basic composition, 0.2 ≦ a ≦ 0.6, 0.2 ≦ b ≦ 0.6, and 0.2 ≦ c ≦ 0.6 may be satisfied. Further, in this basic composition, 0.3 ≦ a ≦ 0.4, 0.3 ≦ b ≦ 0.4, and 0.3 ≦ c ≦ 0.4 may be satisfied. For example, the composite oxide includes a lithium cobalt composite oxide whose basic composition formula is Li _(1-n) CoO ₂ , a lithium nickel composite oxide whose basic composition formula is Li _(1-n) NiO _2, and a basic composition formula Li _(1-n) MnO ₂ (0 <n <1, etc., the same shall apply hereinafter) and Li _(1-n) Mn ₂ O _4, etc., and a basic composition formula of Li _(1-n) Ni _1/3 Co _1/3 Mn _1/3 O ₂ and may be as a lithium-nickel-cobalt-manganese composite oxide. Among these, the composite oxide preferably contains at least Co, and lithium cobalt composite oxide (hereinafter also referred to as LCO) is preferable. In the case of containing Co, it is considered that an interface portion that conducts lithium ions is more easily formed. As the composite oxide, for example, a lithium titanium composite oxide whose basic composition formula is Li ₄ Ti ₅ O ₁₂ or the like, a lithium vanadium composite oxide whose basic composition formula is LiV ₂ O _3, or the like, V ₂ O Transition metal oxides such as ₅ . As the phosphoric acid compound include, for example, LiFePO _4.

The flux contained in the second layer is not particularly limited as long as it contains at least Li and B, and more preferably has lithium ion conductivity. This flux is preferably lithium borate. Examples of the lithium borate include Li ₃ BO ₃ , Li ₂ B ₄ O ₇ and LiBO _2, and among these, Li ₃ BO ₃ (hereinafter also referred to as LBO) is more preferable. LBO is preferable because it has lower reactivity with the composite oxide. Thus, when the second layer contains a flux, the composite oxide can be more firmly fixed on the first layer. The “flux” is not intended to melt the composite oxide particles, but refers to a material that melts the material itself to join the composite oxide onto the first layer.

The interface portion is a portion that exists between the active material and the solid electrolyte and joins the active material particles and the solid electrolyte layer, and includes Li, B, and Si. For example, the interface portion may be formed by segregating SiO ₂ contained in the flux to the interface portion during firing. Due to the presence of the interface portion, the battery characteristics such as the battery capacity can be further improved by improving the bondability between the active material particles and the solid electrolyte.

FIG. 2 is an explanatory diagram of a good composition range of the flux. In this composite laminate, the total composition of the flux and the interface is as follows: Li ₂ O is 32 mass% to 70 mass%, B ₂ O ₃ is 25 mass% to 58 mass%, and SiO ₂ is 2 mass%. It is preferable that it is the range of 30 mass% or less (solid line range). In this range, the battery capacity can be further increased. In addition, this composition is such that Li ₂ O is in the range of 32 mass% to 68 mass%, B ₂ O ₃ is in the range of 30 mass% to 48 mass%, and SiO ₂ is in the range of 2 mass% to 25 mass%. More preferable (one-dot chain line range). Further, this composition may be in the range of 50% by mass to 60% by mass of Li ₂ O, 30% by mass to 48% by mass of B ₂ O _{3, and} 2% by mass to 10% by mass of SiO _2. More preferable (dotted line range). In such a range, the battery performance can be further improved.

  In the composite laminate, the thickness of the first layer may be 0.1 μm or more, 1 μm or more, or 10 μm or more. Further, the thickness of the first layer may be 1 mm or less. The same applies to the thickness of the second layer.

  This composite laminate can be used for lithium batteries. This is because the lithium ion conductivity is higher. At this time, the garnet-type oxide may be used as, for example, a solid electrolyte of a lithium battery, or may be used as a separator of a lithium battery. Such a lithium battery may include a composite laminate including a first layer that is a solid electrolyte and a second layer that is a positive electrode active material, and a negative electrode having a negative electrode active material that can occlude and release lithium. . Examples of the negative electrode active material used for the negative electrode include inorganic compounds such as lithium metal, lithium alloys, and tin compounds, carbonaceous materials capable of inserting and extracting lithium ions, lithium titanium composite oxides, and conductive polymers. The carbonaceous material is not particularly limited, and examples thereof include cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, and carbon fibers.

  The lithium battery of the present invention includes the composite laminate described above. This lithium battery may be a secondary battery or an all solid-state lithium battery. Although the structure of this lithium battery is not specifically limited, For example, the structure shown in FIG. 1 is mentioned. FIG. 1 is an explanatory diagram showing an example of the structure of an all-solid-state lithium battery 10. The lithium battery 10 includes a solid electrolyte layer 11 that is a first layer, a positive electrode active material layer 13 that is a second layer formed on one surface of the solid electrolyte layer 11, and a second surface of the solid electrolyte layer 11. Negative electrode active material layer 16. A current collector 14 is formed on the surface of the positive electrode active material layer 13, and a current collector 17 is formed on the surface of the negative electrode active material layer 16. The positive electrode active material layer 13 includes composite oxide active material particles 21 containing one or more elements of Co, Ni, and Mn, and a flux 22 containing Li. Further, the positive electrode active material layer 13 is formed with an interface portion 24 that is formed between the solid electrolyte layer 11 and the active material particles 21 and is different from the flux 22. The interface portion 24 is a portion that joins the active material particles 21 and the solid electrolyte layer 11 and includes Li, B, and Si.

  Next, the manufacturing method of the composite laminated body of this invention is demonstrated. In this manufacturing method, a second layer containing an active material of a composite compound containing Li and a transition metal and a flux containing Li, B, and Si is formed on the surface of the first layer containing a solid electrolyte to form a laminate. A lamination step and a firing step of firing the laminate.

In the stacking step, a second layer containing an active material of a composite compound containing Li and a transition metal and a flux containing Li, B, and Si is formed on the surface of the first layer containing the solid electrolyte. In this step, as the solid electrolyte, the garnet-type oxide described in the above composite laminate, for example, the basic composition Li _{7 + XY} La _3−X A _X Zr _2−Y T _Y O ₁₂ (wherein the element A is One or more elements selected from the group consisting of Ba, Sr, Ca, Mg and Y, and the element T is composed of Sc, Ti, V, Y, Nb, Hf, Ta, Al, Si, Ga and Ge. One or more elements selected from the group consisting of 0 <X ≦ 1, 0 ≦ Y ≦ 1, and X <Y may be used. The garnet-type oxide can be obtained, for example, by mixing raw material components including Li, La, Zr, further element A, element T, and the like and firing at a temperature of 1100 ° C. or lower. The raw material component is preferably carbonate or hydroxide rather than oxide. At this time, it is preferable to add an excessive amount of Li. The first layer may have a thickness of 0.1 μm or more, 1 μm or more, or 10 μm or more. Further, the thickness of the first layer may be 1 mm or less.

In this step, a second layer containing an active material of a composite compound containing Li and a transition metal and a flux containing Li, B, and Si is formed. As the active material, the composite compound described in the composite laminate, for example, the basic composition LiCo _a Ni _b Mn _c O ₂ (0 ≦ a ≦ 1, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, a + b + c = 1) It is good also as what uses the complex oxide represented by these. Among these, the composite oxide preferably contains at least Co, and lithium cobalt composite oxide and the like are preferable. Examples of the flux include the compounds described in the composite laminate, and may include, for example, at least Li, B, and Si. This flux may be a composite oxide containing Li, B, and Si. Alternatively, the flux may be a mixture of Li ₂ O, B ₂ O ₃ , and SiO ₂ at a predetermined ratio. If Si is contained in the flux component, the Si is segregated at the interface portion in the next firing step. The composition of the flux may include Li ₂ O in a range of 32 mass% to 70 mass%, B ₂ O _{3 in a range} of 25 mass% to 58 mass%, and SiO ₂ in a range of 2 mass% to 30 mass%. preferable. The composition of the flux includes Li ₂ O in a range of 32 mass% to 68 mass%, B ₂ O _{3 in a range} of 30 mass% to 48 mass%, and SiO ₂ in a range of 2 mass% to 25 mass%. It is more preferable. Further, the composition of the flux includes Li ₂ O in a range of 50% by mass to 60% by mass, B ₂ O _{3 in a range} of 30% by mass to 48% by mass, and SiO ₂ in a range of 2% by mass to 10% by mass. More preferably. In such a range, the battery capacity can be further increased, which is preferable. The method for forming the second layer is not particularly limited, and for example, the raw material particles may be paste-formed and screen-printed, or a doctor blade method may be employed. This second layer may have a thickness of 0.1 μm or more, 1 μm or more, or 10 μm or more. The thickness of the second layer may be 1 mm or less.

  In the firing step, the laminate is fired. In this step, for example, the laminate is fired at a firing temperature of 1100 ° C. or lower. In this firing step, there is no problem as long as the laminate is fired by applying pressure, but the laminate is preferably fired in an atmospheric pressure atmosphere. If it carries out like this, a composite laminated body can be baked with a simple process. The firing temperature is more preferably 1050 ° C. or less, and still more preferably 1000 ° C. or less. This is because the firing energy can be further reduced. In consideration of the sinterability of the first layer and the second layer, the firing temperature is preferably 700 ° C. or higher, more preferably 750 ° C. or higher, and still more preferably 800 ° C. or higher. If the sinterability can be improved, the temperature may be 850 ° C. or higher. Thus, the composite laminate 20 having the interface portion 24 can be manufactured.

  In the composite laminate, the lithium battery, and the method for producing the composite laminate described in detail above, the battery performance can be further improved by further improving the bondability between the solid electrolyte layer and the active material layer. The reason why such an effect is obtained is presumed as follows. For example, the interface portion generated between the active material and the solid electrolyte contains Li, B, Si, and O, and is presumed to have low Li ion conductivity. On the other hand, it is surmised that this interface part has improved the contact property between the active material and the solid electrolyte. As a result, the ionic conductivity between the active material and the solid electrolyte is improved, and the battery capacity is improved. It is inferred that the battery performance can be further improved, such as improvement.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the method for manufacturing a composite laminate is described. However, a method for manufacturing a lithium battery may further include a negative electrode forming step of forming a negative electrode active material layer on the surface opposite to the first layer. In the negative electrode forming step, for example, a negative electrode active material layer may be formed using Li metal by any one of sputtering, chemical vapor deposition, ion coating, and PLD. Alternatively, Li metal or Li alloy may be pressure-bonded to the surface of the first layer.

  Below, the example which produced the composite laminated body of this invention concretely is demonstrated as an experiment example. Experimental examples 2, 3, 5-9, 11, and 13 correspond to examples, and experimental examples 1, 4, 10, 12, and 14 correspond to comparative examples.

[Production of garnet-type oxide]
Li _6.75 La ₃ Zr _1.75 Nb _0.25 O ₁₂ (LLZ) was synthesized as a garnet oxide. The starting materials were Li ₂ CO ₃ , La (OH) ₃ , ZrO ₂ and Nb ₂ O ₅ . The starting material was weighed to a stoichiometric ratio. However, in order to make up for the loss of Li in the main sintering, 10 at. Li ₂ CO ₃ was excessively added so as to be a%. Using zirconia balls, mixing and pulverization were performed in ethanol in a planetary ball mill (300 rpm) for 1 hour. After separating the mixed powder of the starting material from the balls and ethanol, LLZNb was calcined in an air atmosphere at 950 ° C. for 10 hours in an Al ₂ O ₃ crucible. Then, this mixed powder was mixed and ground for 1 hour in a planetary ball mill (300 rpm) in ethanol using zirconia balls. The obtained powder was calcined again under the above conditions (950 ° C., 10 hours, air atmosphere), and then formed into a pellet having a diameter of 13 mm. This pellet was sintered at 1150 ° C. for 36 hours in an air atmosphere to obtain a sample (solid electrolyte layer).

[Composite oxide]
As a LiCoO ₂ (LCO), a cell seed 10N manufactured by Nippon Chemical Co., Ltd. was used.

[Flux]
As the flux, Li ₂ O, B ₂ O ₃ , and SiO ₂ were mixed at a predetermined ratio. The mixing ratio is shown in Table 1.

(Electrical conductivity)
The electrical conductivity of the solid electrolyte layer was measured. Using an AC impedance analyzer (Agilent 4294A) in a thermostatic chamber, a resistance value was determined from the arc of the Nyquist plot under the conditions of a frequency of 40 Hz to 110 MHz and an amplitude voltage of 100 mV, and the electrical conductivity was calculated from the resistance value. An Au electrode was used as a blocking electrode when measuring with an AC impedance analyzer. The Au electrode was formed by baking a commercially available Au paste at 850 ° C. for 30 minutes. As a result of the measurement, the solid electrolyte layer had an electric conductivity of 5 × 10 ⁻⁴ Scm ⁻¹ .

[Production of composite laminate]
An active material layer (second layer) containing a composite oxide was laminated on the surface of the solid electrolyte layer (first layer) (lamination step). A predetermined amount of the above powder flux, composite oxide (LCO), and binder (EC vehicle, EC-200 FTD manufactured by Nisshin Kasei) were weighed and kneaded to obtain an active material mixture paste. A mask having an opening with a diameter of 6 mm was placed on the solid electrolyte layer, and the paste was screen-printed to obtain a laminate. Subsequently, the laminate was fired (firing step). The above laminate was placed in a firing furnace, held at 750 ° C. for 1 hour, and then cooled in a furnace to obtain a composite laminate. As the composition of the flux shown in Table 1, composite laminates of Experimental Examples 1 to 14 were obtained.

[Preparation of all-solid lithium secondary battery]
Au was ion-coated on the surface of the active material layer of the composite laminate, and an Al thin plate was disposed as a positive electrode current collector. Moreover, Li metal as a negative electrode active material was vapor-deposited on the back surface of the solid electrolyte layer, and a Cu thin plate was disposed as a negative electrode current collector to obtain all solid lithium secondary batteries of Experimental Examples 1-14.

(SEM observation)
The cross section of the fabricated laminated composite of Experimental Example 4 was observed with a scanning electron microscope (SEM). SEM observation was performed under conditions of 2000 to 5000 times using Hitachi High-Technologies S-3600N. FIG. 3 is an SEM photograph of a cross section of the composite laminate. As shown in FIG. 3, in the composite laminate of Experimental Example 4, an interface including Li, Si, B, and O that joins the active material particles and the solid electrolyte layer was formed. Moreover, the flux containing Li, B, and O was confirmed in the part different from the interface part. Although the specific composition of the interface is unknown, for example, although it is assumed that the material has a composition close to borosilicate glass (although the alkaline element is Li), the active material particles are considered to have low ionic conductivity. It was inferred that was adhered to the surface of the solid electrolyte layer.

(Battery evaluation)
As a battery evaluation, a cyclic voltammogram (CV) was measured. CV measurement was performed using an electrochemical measurement system (HZ-3000, manufactured by Hokuto Denko). After measuring the open circuit voltage (OCV), the potential was swept between 3.0 V and 4.05 V at a sweep speed of 0.1 mV / s. A provisional C rate was calculated from the flowing current. The battery was charged (3.0 V → 4.05 V) and discharged (4.05 V → 3.0 V) at 0.1 C to obtain a more accurate charge / discharge capacity (Q ₀ ), and the C rate was calculated. The battery was charged at 0.1 C to 4.05 V, and further charged at 4.05 V for 1 hour. After resting for 1 hour, the battery was discharged to 3.0 V at a predetermined current value and rested for 1 hour. The discharge capacity was measured by decreasing the current value in order of 200 μA, 100 μA, and 50 μA. With the measured current value, the discharge capacity measured with a larger current value was also obtained, and the sum of these discharge capacities was defined as the discharge capacity Q (mAh / g). Also, the discharge capacity Q is normalized by the discharge capacity Q ₀ when all the active materials contained in the composite laminate are discharged (Q / Q ₀ ), and this Q / Q ₀ and the discharge current I (I (I) converted to the C rate are calculated. / C) was examined.

(Results and discussion)
The measurement results of Experimental Examples 1 to 14 are shown in Table 1. FIG. 4 is a relationship diagram between the discharge current I / C and the discharge capacity Q / Q ₀ of the all-solid lithium secondary batteries of Experimental Examples 1 to 4. Figure 5 is a graph showing the relationship between the composition of the flux and the discharge capacity Q / Q _0. FIG. 5 shows the value of the discharge capacity Q / Q ₀ at the 0.01 C rate in FIG. As shown in FIG. 5 and Table 1, the composition of the entire flux is such that Li ₂ O is 32 mass% to 70 mass%, B ₂ O ₃ is 25 mass% to 58 mass%, and SiO ₂ is 2 mass%. In the range of 30% by mass or less (solid line in FIG. 5), the discharge capacity Q / Q ₀ showed a favorable value as compared with the case where the flux did not contain SiO ₂ . Further, the composition of the entire flux is in the range of 32% to 68% by mass of Li ₂ O, 30% to 48% by mass of B ₂ O ₃ , and 2% to 25% by mass of SiO ₂ ( In the one-dot chain line in FIG. 5, the discharge capacity Q / Q ₀ was more preferable. Further, the composition of the entire flux is in the range of 50% to 60% by weight of Li ₂ O, 30% to 48% by weight of B ₂ O ₃ , and 2% to 10% by weight of SiO ₂ ( In the dotted line in FIG. 5, the discharge capacity Q / Q ₀ was most preferable at 35% or more. The interface portion formed between the active material of the composite oxide and the solid electrolyte contains Li, B, Si and O, and is presumed to have low conductivity of Li ions. It is presumed that the battery capacity and the like can be further improved by improving the bondability, for example, the ion conductivity of both substances is improved because the bondability between the substance and the solid electrolyte is excellent. In addition, what contained Li, B, and O existed between active materials.

  In addition, this invention is not limited to the Example mentioned above at all, and as long as it belongs to the technical scope of this invention, it cannot be overemphasized that it can implement with a various aspect.

  The present invention can be used in the technical field of the battery industry.

  DESCRIPTION OF SYMBOLS 10 Lithium battery, 11 Solid electrolyte layer, 12 Positive electrode, 13 Positive electrode active material layer, 14 Current collector, 15 Negative electrode, 16 Negative electrode active material layer, 17 Current collector, 20 Composite laminated body, 21 Active material particle, 22 Flux 24 Interface part.

Claims (8)

A first layer comprising a solid electrolyte;
A second layer containing an active material of a composite compound containing Li and a transition metal, and a flux containing Li and B;
An interface between Li and B and Si that exists between the active material and the solid electrolyte;
A composite laminate comprising: The total composition of the flux and the interface is as follows: Li ₂ O is 32 mass% to 70 mass%, B ₂ O ₃ is 25 mass% to 58 mass%, and SiO ₂ is 2 mass% to 30 mass%. The composite laminated body of Claim 1 which is the range of the mass% or less. The total composition of the flux and the interface is as follows: Li ₂ O is 32 mass% to 68 mass%, B ₂ O ₃ is 30 mass% to 48 mass%, and SiO ₂ is 2 mass% to 25 mass%. The composite laminated body of Claim 1 which is the range of the mass% or less. The total composition of the flux and the interface portion is as follows: Li ₂ O is 50 mass% to 60 mass%, B ₂ O ₃ is 30 mass% to 48 mass%, and SiO ₂ is 2 mass% to 10 mass%. The composite laminated body of Claim 1 which is the range of the mass% or less. The solid electrolyte is a garnet-type oxide containing at least Li, La, and Zr,
5. The composite laminate according to claim 1, wherein the active material is a composite compound containing one or more of Fe, Co, Ni, Mn, and Ti.   The lithium battery provided with the composite laminated body of any one of Claims 1-5. A laminating step in which a second layer containing an active material of a composite compound containing Li and a transition metal and a flux containing Li, B, and Si is formed on the surface of the first layer containing a solid electrolyte to form a laminate;
A firing step of firing the laminate;
The manufacturing method of the composite laminated body containing this. In the lamination step, the composition of the flux used is Li ₂ O of 32% by mass to 70% by mass, B ₂ O ₃ of 25% by mass to 58% by mass, and SiO ₂ of 2% by mass to 30% by mass. The manufacturing method of the composite laminated body of Claim 7 included in the range.