JP6340955B2 - Method for producing composite laminate, composite laminate and lithium battery - Google Patents

Description

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

  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 making the garnet-type oxide of patent document 1 into a lithium secondary battery, a positive electrode active material layer is formed in the surface. 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, when it is necessary to discharge with a large current, such as a battery for an electric vehicle, it has been desired to further improve the lithium ion conductivity between the solid electrolyte layer and the active material layer. .

  The present invention has been made in view of such problems, and it is a main object of the present invention to provide a method for manufacturing a composite laminate, a composite laminate, and a lithium secondary battery capable of performing discharge with a larger current. To do.

  As a result of diligent research to achieve the above-described object, the present inventors have found that the metal contained in the active material particles (composite oxide particles) on the surface of the solid electrolyte layer (first layer) containing Li, La, and Zr. After forming a thin film containing, it was found that discharge with a larger current can be performed by laminating active material particles to produce a composite laminate, and the present invention has been completed.

That is, the method for producing the composite laminate of the present invention includes:
Forming an intermediate layer made of a metal and / or compound containing one or more of Co, Ni and Mn on the surface of the first layer containing a garnet-type oxide containing at least Li, La and Zr;
A second layer including a composite oxide particle containing one or more elements of Co, Ni, and Mn contained in the intermediate layer and a flux containing Li is formed on the intermediate layer; Laminating process to
A firing step of firing the laminate;
Is included.

The composite laminate of the present invention is
A first layer including a garnet-type oxide containing at least Li, La, and Zr;
A second layer comprising particles of a composite oxide containing one or more elements of Co, Ni and Mn and a flux containing Li;
An interface portion containing one or more elements of Co, Ni and Mn contained in the composite oxide and different from the flux formed in the flux between the first layer and the composite oxide particles And.

  In the present invention, discharge with a larger current can be performed. The reason why such an effect is obtained is presumed as follows. For example, the first layer containing a garnet-type oxide containing at least Li, La, and Zr has a property that Li is likely to precipitate on the surface thereof when fired. In the present invention, an intermediate layer containing one or more elements of Co, Ni, and Mn contained in the composite oxide is formed on the first layer in advance, thereby reacting with the deposited Li, and lithium It is presumed that an interface portion that more easily conducts ions is formed. This interface portion increases the conductivity of the lithium ions between the active material particles and the first layer, so that it is presumed that discharge with a larger current can be performed.

FIG. 2 is an explanatory diagram showing an example of the structure of an all-solid-type lithium battery 10. Explanatory drawing which shows an example of the process of producing the composite laminated body. 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. Relationship diagram between Co mass formed on the solid electrolyte and the discharge capacity Q / Q _0.

  The composite laminate of the present invention contains a first layer containing a garnet-type oxide (hereinafter also referred to as LLZ) containing at least Li, La, and Zr, and one or more elements of Co, Ni, and Mn. A second layer including composite oxide particles and a Li-containing flux; and one or more elements of Co, Ni, and Mn contained in the composite oxide, and the first layer and the composite oxidation in the flux And an interface portion different from the flux formed between the product particles. In this composite laminate, the first layer is a solid electrolyte layer containing a garnet-type oxide having lithium ion conductivity, and the second layer is an active material layer containing composite oxide particles that occlude and release lithium ions. It may be a thing.

The garnet-type oxide contained in the first layer contains Li, La, and Zr, and is an element different from La, and is different from at least one element A among alkaline earth metals and lanthanoid elements, and Zr. It is good also as a thing containing at least 1 or more types of element T among the transition elements which are elements and can take 6-coordinate with oxygen, 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.

  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. Note that 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 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.

The composite oxide contained in the second layer contains one or more of Ni, Co, and Mn, but may further contain Li. For example, the composite oxide may be expressed 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). preferable. 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.

The flux contained in the second layer is not particularly limited as long as it contains at least Li, and a flux having lithium ion conductivity is more preferable. This flux is preferably a compound containing Li and B, particularly 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 part is a part for joining the active material particles and the solid electrolyte layer. For example, the interface portion may have a constricted shape between the active material particles and the solid electrolyte layer. This interface portion contains one or more elements of Co, Ni and Mn contained in the composite oxide, but is more preferably formed of a compound having lithium ion conductivity. Moreover, the interface part may be composed of a compound similar to the composite oxide, for example. The presence of this interface portion allows lithium ions to move quickly.

  In the composite laminate of the present invention, 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. The same applies to the thickness of the second layer.

  The composite laminated body of this invention can be utilized for a lithium battery. 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 includes 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. The solid electrolyte layer 11 containing a garnet-type oxide and the positive electrode active material layer 13 containing active material particles 21 that are a composite oxide are the composite laminate 20 of the present invention. 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 contains one or more elements of Co, Ni, and Mn contained in the active material particles 21, and is interposed between the solid electrolyte layer 11 and the active material particles 21 in the flux 22. The formed interface part 24 different from the flux 22 is formed. The interface portion 24 is a portion where the active material particles 21 and the solid electrolyte layer 11 are joined, and may have a constricted shape.

  Next, the manufacturing method of the composite laminated body of this invention is demonstrated. The manufacturing method of the composite laminated body of this invention includes the formation process which forms an intermediate | middle layer, the lamination process which laminates | stacks a 2nd layer, and the baking process which bakes the laminated body laminated | stacked. FIG. 2 is an explanatory view showing an example of a process for producing the composite laminate 20.

In the forming step, an intermediate layer made of a metal and / or compound containing one or more of Co, Ni and Mn is formed on the surface of the first layer containing a garnet-type oxide containing at least Li, La and Zr. (See FIG. 2 (a)). The “intermediate layer” may be a thin film that is completely covered or may be incompletely covered. In this step, the garnet-type oxide described in the 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 Ba, Sr, One or more elements selected from the group consisting of Ca, Mg and Y, and the element T is selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Al, Si, Ga and Ge A garnet-type oxide represented by 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. The intermediate layer is made from one or more metals and / or compounds of Co, Ni and Mn contained in the composite oxide. Among these, it is preferable that the composite oxide contains at least Co, and the raw material of the intermediate layer contains at least Co. A compound containing Co is preferable because it easily conducts lithium ions. This intermediate layer can be made of a metal, an alloy, an oxide, a mixture thereof, or the like as a raw material. Among these, a metal is preferable. The method for forming the intermediate layer is not particularly limited, but for example, it is preferably performed by any one of sputtering, chemical vapor deposition, ion coating, and PLD. Further, the intermediate layer raw material particles may be pasted and screen-printed, or a doctor blade method may be employed. For example, the intermediate layer is preferably formed at a coating amount of 50 μg / cm ² or more, more preferably 80 μg / cm ² or more, and further preferably 150 μg / cm ² or more. . When the formation amount is 50 μg / cm ² or more, an interface portion is easily formed, and discharge with a large current (for example, 1 C rate or more) is easily performed. The formation amount is preferably 500 μg / cm ² or less from the viewpoint of material consumption. Further, the thickness of the intermediate layer is, for example, preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more. This thickness is preferably 1 μm or less. Thus, when an intermediate layer (thin film) is formed on the first layer, an interface portion can be formed between the composite oxide particles and the first layer in the subsequent firing step.

In the laminating step, a second layer containing composite oxide particles containing one or more elements of Co, Ni, and Mn contained in the intermediate layer and a flux containing Li is formed on the intermediate layer. And a laminated body (see FIG. 2B). In this step, the composite oxide 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 it is particularly preferable to use a compound containing Li and B, and lithium borate is preferable. As the flux, Li ₃ BO ₃ (hereinafter also referred to as LBO) is more preferable. 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 further 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 800 ° C. or higher, more preferably 900 ° C. or higher, and further preferably 950 ° C. or higher. If the sinterability can be improved, the temperature may be 750 ° C. or higher. In this way, the composite laminate 20 having the interface portion 24 can be manufactured (see FIG. 2C).

  With the composite laminate and the manufacturing method thereof described in detail above, it is possible to provide a composite laminate that can be discharged with a larger current. The reason why such an effect is obtained is presumed as follows. For example, the first layer containing a garnet-type oxide containing at least Li, La, and Zr has a property that Li is likely to precipitate on the surface thereof when fired. Here, an intermediate layer containing one or more elements of Co, Ni, and Mn contained in the composite oxide is formed on the first layer in advance, thereby reacting with the precipitated Li, and lithium It is presumed that an interface portion that more easily conducts ions is formed. This interface portion increases the conductivity of the lithium ions between the active material particles and the first layer, so that it is presumed that discharge with a larger current can be performed.

  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 Example.

[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 synthesis]
Li ₃ BO ₃ (LBO) was obtained by using Li ₂ CO ₃ and B ₂ O ₃ as starting materials, weighing them to a stoichiometric ratio, mixing them with a ball mill, and firing at 600 ° C. for 10 hours.

(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]
A Co metal layer (intermediate layer) was formed on the surface of the solid electrolyte layer (first layer) (forming step). After polishing the surface of the solid electrolyte layer of the garnet-type oxide, a mask having an opening with a diameter of 6 mm was placed on the surface, and set in an ion coater using Co metal as a target. After reducing the pressure to 10 Pa with a rotary pump, 400 to 600 V was applied, and Co was ion-coated on the surface of the solid electrolyte layer. The mass increase of the solid electrolyte layer after the treatment was measured, and the amount of coated Co was determined. Next, an active material layer (second layer) containing a composite oxide was laminated on the Co metal layer (lamination process). 2.7 g of flux (LBO), 7.3 g of composite oxide (LCO), and 10 g of binder (EC vehicle, Nisshin Kasei EC-200FTD), weighed and kneaded and mixed with active material paste It was. A mask having an opening with a diameter of 6 mm was placed on a region of the solid electrolyte layer where Co was ion-coated, 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. This was designated as the composite laminate of Example 1. The increase in mass of the composite laminate after the firing treatment was measured, and the amount of active material contained was determined from the measured mass and raw material composition. Moreover, what was obtained through each said process except not forming the said intermediate | middle layer was used as the composite laminated body of the comparative example 1. FIG.

[Preparation of all-solid lithium secondary battery]
Au was ion-coated to 100 nm on the surface of the active material layer of the composite laminate of Example 1, 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 an all solid lithium secondary battery of Example 1. Moreover, the all-solid-state lithium secondary battery of the comparative example 1 was obtained through the process similar to Example 1 using the composite laminated body of the comparative example 1. FIG.

(SEM observation)
The cross section of the produced laminated composite of Example 1 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 Example 1, the intermediate layer formed in the formation process did not remain clearly. Further, instead of the intermediate layer, a constricted interface portion different from the flux that joins the active material particles and the solid electrolyte layer is formed. The specific composition of this interface portion is unknown, but, for example, in the firing step, Li released from the solid electrolyte layer reacts with Co metal in the intermediate layer, and a compound such as LCO similar to the active material It was guessed that was formed and formed.

(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 cycle was measured from OCV to 4.05 V, 2.50 V, and 4.05 V with respect to the negative electrode (Li metal) at a sweep rate of 0.1 V / s. As a result, it was confirmed that both Example 1 and Comparative Example 1 operated as a battery. Next, a temporary C rate is set from the obtained electric quantity, and the negative electrode is charged from 2.50 V to 4.05 V at a value of 1/10, and discharged from 4.05 V to 2.50 V. Thus, a more accurate charge / discharge amount was obtained, and the C rate was calculated. Next, it charged to 4.05V with respect to the negative electrode at 0.1 C, and it charged by hold | maintaining at 4.05V for 1 hour. After 1 hour of rest, the battery was discharged to a final voltage of 2.50 V (counter negative electrode) at a discharge current value of 500 μA. Further, the discharge capacity was measured by decreasing the current values in order of 200 μA, 100 μA, and 50 μA with a pause of 1 hour in between. 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. In addition, composite laminates with different intermediate layer formation amounts (Co amounts) were prepared, and the discharge capacity was measured.

(Results and discussion)
The measurement results of Example 1 and Comparative Example 1 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 Example 1 and Comparative Example 1. As shown in FIG. 4 and Table 1, in Comparative Example 1, although the discharge capacity at a low current value was relatively high, the discharge capacity decreased greatly as the C rate increased, and there was almost no discharge capacity at 1C. On the other hand, in Example 1 produced by forming an intermediate layer on the surface of the solid electrolyte layer, it was found that the discharge capacity at 0.1 C or higher, particularly 1 C, was remarkably improved. From this result, in Example 1, it was guessed that the movement of the lithium ion between the solid electrolyte layer and the composite oxide (active material particles) became quick. The reason was presumed as follows. For example, a solid electrolyte layer (first layer) containing a garnet-type oxide containing at least Li, La, and Zr has a property that Li is likely to precipitate on the surface thereof when fired. The deposited Li may form an alkali metal compound layer (resistance layer) that is difficult to conduct lithium ions. In the composite laminate of Comparative Example 1, the composite oxide is joined directly or via a resistance layer on the solid electrolyte layer. For this reason, since it is in a state close to point contact or through a resistance layer, it was assumed that the amount of lithium ion transfer between the solid electrolyte and the composite oxide was small. In contrast, in the composite laminate of Example 1, an intermediate layer containing one or more elements of Co, Ni, and Mn contained in the composite oxide is formed on the first layer in advance. It was inferred that this interfaced with Li deposited to form an interface part that more easily conducts lithium ions. For example, it is presumed that this interface portion easily contains Li and Co, and therefore, it is presumed that the interface portion is a compound similar to the complex oxide (LCO) that easily moves lithium ions. Since the interface part increases the conductivity of lithium ions between the active material particles and the first layer, it is presumed that discharge with a larger current can be performed.

FIG. 5 is a graph showing the relationship between the Co mass of the intermediate layer formed on the solid electrolyte and the discharge capacity Q / Q ₀ during 1C discharge. The measurement results are shown in Table 2. As shown in FIG. 5 and Table 2, it was found that when the amount of Co formed is 50 μg / cm ² or more, discharge at a higher rate can be performed. It was speculated that the formation amount of this intermediate layer is more preferably 500 μg / cm ² or less.

  In Example 1, Co metal was formed on the surface of the solid electrolyte layer as the intermediate layer. However, since the oxide of the Co metal particles is also included on the surface of the Co metal particle, the intermediate layer is made of Co oxide. Even if it is formed of a material containing it, it is presumed that an effect equivalent to that of the above embodiment can be obtained. Further, in the examples, the positive electrode active material layer and the intermediate layer containing Co were used, but it was speculated that the same effect can be obtained with Ni and Mn.

  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 , 23 Intermediate layer, 24 Interface part.

Claims (12)

Forming an intermediate layer made of a metal and / or compound containing one or more of Co, Ni and Mn on the surface of the first layer containing a garnet-type oxide containing at least Li, La and Zr;
A second layer including a composite oxide particle containing one or more elements of Co, Ni, and Mn contained in the intermediate layer and a flux containing Li is formed on the intermediate layer; Laminating process to
Look including a firing step of firing the laminate,
In the firing step, the laminate is fired to form an interface portion different from the flux between the first layer and the composite oxide particles in the flux. . The method for producing a composite laminate according to claim 1, wherein in the forming step, the intermediate layer is formed in an amount of 50 μg / cm ² or more. In the forming step, Co metal is formed as the intermediate layer,
The method for producing a composite laminate according to claim 1, wherein, in the lamination step, particles of the composite oxide containing at least Co are used.   In the said formation process, the said intermediate | middle layer is formed in any one method among a sputtering method, a chemical vapor deposition method, an ion coat method, and a PLD method, The manufacture of the composite laminated body of any one of Claims 1-3 Method.   The manufacturing method of the composite laminated body of any one of Claims 1-4 which uses the compound containing Li and B as the said flux at the said lamination process. In the forming step, the basic composition Li _{7 + XY} La _3−X A _X Zr _2−Y T _Y O ₁₂ (wherein the element A is selected from the group consisting of Ba, Sr, Ca, Mg and Y) The element T is one or more elements, and the element T is one or more elements selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Al, Si, Ga, and Ge, and 0 <X The manufacturing method of the composite laminated body of any one of Claims 1-5 using the said garnet-type oxide represented by <= 1, 0 <= Y <= 1, and X <Y. In the stacking step, the composite oxide 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) is used. Item 7. The method for producing a composite laminate according to any one of Items 1 to 6. A first layer including a garnet-type oxide containing at least Li, La, and Zr;
A second layer comprising particles of a composite oxide containing one or more elements of Co, Ni and Mn and a flux containing Li;
An interface portion containing one or more elements of Co, Ni and Mn contained in the composite oxide and different from the flux formed in the flux between the first layer and the composite oxide particles When,
A composite laminate comprising: 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 selected from the group consisting of Ba, Sr, Ca, Mg and Y). The element T is one or more elements selected from the group consisting of Sc, Ti, V, Y, Nb, Hf, Ta, Al, Si, Ga, and Ge. <X ≦ 1,0 ≦ Y ≦ 1 , represented by X <satisfy Y), the composite laminate according to claim 8. Said composite oxide is represented by the basic composition _{LiCo a Ni b Mn c O 2} (0 ≦ a ≦ 1,0 ≦ b ≦ 1,0 ≦ c ≦ 1, a + b + c = 1), to claim 8 or 9 The composite laminate described. The composite laminate according to any one of claims 8 to 10 , wherein the flux is a compound containing Li and B. With a composite laminate according to any one of claims 8-11, a lithium battery.