semi-solid batteries

Abstract

This promotes ion movement within the electrolyte layer, where the amount of electrolyte solution is small. [Solution] The semi-solid battery 1 comprises a positive electrode layer 10 including a positive electrode current collector 11 and a positive electrode active material 12, a negative electrode layer 20 including a negative electrode current collector 21 and a negative electrode active material 22, and an electrolyte layer 30 provided between the positive electrode layer 10 and the negative electrode layer 20, with a fluid electrolyte 32 between adjacent solid electrolyte particles 31. The electrolyte layer 30 includes oxide particles 33 that are in contact with the solid electrolyte particles 31 and adsorb the electrolyte 32.

Description

Technical Field

[0001] The present invention relates to a semi-solid battery.

Background Art

[0002] The all-solid-state secondary battery of Patent Document 1 includes a positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a negative electrode current collector and a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode and the negative electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the solid electrolyte layer, ions move in a region where the solid electrolyte is in contact with other solid electrolytes. However, if the region of each solid electrolyte is small, the resistance to ion movement increases. Therefore, a measure of including an electrolytic solution in the solid electrolyte layer to make the region different from this region ion-movable can be considered. However, in this measure, the larger the amount of the electrolytic solution, the more likely problems such as the viscosity of the electrolytic solution increasing and the resistance increasing at low temperatures, or the electrolytic solution decomposing at high temperatures occur. On the other hand, if the amount of the electrolytic solution is small, problems such as a solid electrolyte to which the electrolytic solution does not adhere increasing the resistance to ion movement and the electrolytic solution solidifying occur.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to promote ion movement in an electrolyte layer with a small amount of electrolytic solution.

Means for Solving the Problems

[0006] A semi-solid battery according to an aspect of the present invention comprises a positive electrode layer including a positive electrode current collector and a positive electrode active material, a negative electrode layer including a negative electrode current collector and a negative electrode active material, and an electrolyte layer provided between the positive electrode layer and the negative electrode layer, wherein the electrolyte layer contains oxide particles that are in contact with the solid electrolyte particles and adsorb the electrolyte.

[0007] The electrolyte layer may have a plurality of solid electrolyte particles, a plurality of oxide particles, a void surrounded by the plurality of solid electrolyte particles, and the electrolyte located in a part of the void.

[0008] The electrolyte layer may include oxide particles with a particle size smaller than that of the solid electrolyte particles, which are coated on the surface of the solid electrolyte particles.

[0009] The electrolyte layer may include a predetermined number or less of the oxide particles coated on the surface of the solid electrolyte particles at predetermined intervals.

[0010] The surface of the solid electrolyte particles may include a region coated with the oxide particles and a region not coated with the oxide particles.

[0011] The oxide particles may include zirconia oxide or tungsten dioxide.

[0012] The positive electrode layer may include the oxide particles coated on the surface of the positive electrode active material, and the negative electrode layer may also include the oxide particles coated on the surface of the negative electrode active material. [Effects of the Invention]

[0013] According to the present invention, the effect of promoting ion movement within an electrolyte layer with a small amount of electrolyte is achieved. [Brief explanation of the drawing]

[0014] [Figure 1]This figure shows an overview of the semi-solid battery 1 according to this embodiment. [Figure 2] This diagram shows the paths of ions moving through the electrolyte solution 32. [Figure 3] This figure shows the cell's resistance value relative to the amount of electrolyte. [Figure 4] This figure shows the input and output of the semi-solid battery 1 as a function of temperature. [Figure 5] This figure shows solid electrolyte particles 31 coated with oxide particles 33. [Modes for carrying out the invention]

[0015] <Overview of Semi-Solid Battery 1> Figure 1 shows an overview of the semi-solid battery 1 according to this embodiment. The semi-solid battery 1 shown in Figure 1 comprises a positive electrode layer 10, a negative electrode layer 20, and an electrolyte layer 30, which are stacked in the order of negative electrode layer 20, electrolyte layer 30, and positive electrode layer 10. The semi-solid battery 1 is a secondary battery, for example, a lithium-ion battery.

[0016] The positive electrode layer 10 is a layer that functions as the positive electrode to which ions (lithium ions in the case of a lithium-ion battery) move when the semi-solid battery 1 discharges, and includes a positive electrode current collector 11 and a positive electrode active material 12. The positive electrode current collector 11 is a conductor for collecting current, for example, aluminum. The positive electrode active material 12 is a material that receives ions during discharge, for example, lithium cobalt oxide.

[0017] The negative electrode layer 20 is a layer that functions as a negative electrode to which ions move when the semi-solid battery 1 is charged, and includes a negative electrode current collector 21 and a negative electrode active material 22. The negative electrode current collector 21 is a conductor for collecting current, for example, copper. The negative electrode active material 22 is a material that receives ions during charging, for example, graphite.

[0018] The electrolyte layer 30 is provided between the positive electrode layer 10 and the negative electrode layer 20 and contains a plurality of solid electrolyte particles 31. The solid electrolyte particles 31 are substances for moving ions to the positive electrode active material 12 when the semi-solid battery 1 discharges and moving ions to the negative electrode active material 22 when the semi-solid battery 1 charges. As an example, the solid electrolyte particles 31 are oxide-based solid electrolytes such as perovskite-type La0.51Li0.34TiO2.94, but may also be sulfide-based solid electrolytes, halide-based solid electrolytes, or hydride-based solid electrolytes.

[0019] In the electrolyte layer 30, there is an electrolytic solution 32 having fluidity between adjacent solid electrolyte particles 31. The electrolytic solution 32 is, for example, a mixed solvent of cyclic carbonate and chain carbonate, and specifically, a mixed solvent of ethylene carbonate and dimethyl carbonate.

[0020] With the presence of the electrolytic solution 32 as described above, ions can move along the path with the shorter distance among the path of moving along the surface where the solid electrolyte particles 31 contact other solid electrolyte particles 31 and the path of moving through the electrolytic solution 32 contacting the solid electrolyte particles 31 and other solid electrolyte particles 31. Specifically, when there is no electrolytic solution 32, ions move along the path R1 shown in FIG. 1, but when there is an electrolytic solution 32, ions move along the path R2 with a shorter distance than the path R1. As a result, in the semi-solid battery 1, the time for ions to move can be shortened compared to the case without the electrolytic solution 32, making it easier to increase the output.

[0021] However, in the case of low temperature (for example, 5°C or lower), the viscosity of the electrolytic solution 32 increases, resulting in an increase in internal resistance and a decrease in voltage, so the charge-discharge capacity decreases. On the other hand, in the case of high temperature (for example, 40°C or higher), the electrolytic solution 32 reacts with the positive electrode active material 12 and the negative electrode active material 22 or self-decomposes, so the charge-discharge capacity decreases. Therefore, in order to suppress the decrease in the charge-discharge capacity due to such temperature changes, if the amount of the electrolytic solution 32 in the electrolyte layer 30 is reduced, problems such as it being difficult for the solid electrolyte particles 31 not adhered with the electrolytic solution 32 to move ions and the electrolytic solution 32 solidifying occur.

[0022] In contrast, the electrolyte layer 30 contains oxide particles 33 that are in contact with the solid electrolyte particles 31 and adsorb the electrolyte 32. The oxide particles 33 are oxides of metal elements that are larger in size than metal elements such as nickel and aluminum, for example, zirconia oxide or tungsten dioxide. With this configuration, in the electrolyte layer 30, the oxide particles 33 that have adsorbed the electrolyte 32 are dispersed in contact with each solid electrolyte particle 31, so that each solid electrolyte particle 31 can come into contact with the electrolyte 32 even if the amount of electrolyte 32 is small. As a result, in the electrolyte layer 30, ions can move more easily through the electrolyte 32 even if the amount of electrolyte 32 is small.

[0023] Furthermore, in the vicinity of the oxide particles 33, the melting point of the electrolyte 32 is lowered and the ionic conductivity is increased due to the oxide particles 33, thus suppressing a decrease in charge / discharge capacity in the electrolyte layer 30. In addition, in the electrolyte layer 30, by using oxides of zirconia or tungsten, which are large metal elements, as oxide particles 33, the surface area of ​​the oxide particles 33 can be increased. As a result, the oxide particles 33 can more easily suppress a decrease in charge / discharge capacity, and the reaction of the oxide particles 33 with the solid electrolyte particles 31 causes diffusion of metal elements, which can suppress changes in the crystal structure of the solid electrolyte particles 31 and make it difficult for ions to move. The composition of the electrolyte layer 30 will be described in detail below.

[0024] <Composition of the electrolyte layer 30> As shown in Figure 1, the electrolyte layer 30 has a plurality of solid electrolyte particles 31, a plurality of oxide particles 33, a void 34 surrounded by the plurality of solid electrolyte particles 31, and an electrolyte 32 in a part of the void 34. For example, if the volume of the void 34 in relation to the volume of the electrolyte layer 30 is 20%, the size of the part of the void 34 is 25% of that 20% (i.e., 5% of the volume of the electrolyte layer 30).

[0025] Furthermore, since oxide particles 33 containing zirconia oxide or tungsten dioxide do not allow ions to pass through the interior of the oxide particles 33, the ions move through the electrolyte 32 adsorbed on the oxide particles 33. Figure 2 is a diagram showing the path of ions moving through the electrolyte 32. Figure 2 shows a plurality of solid electrolyte particles 31 (solid electrolyte particles 31a, 31b, and 31c), the electrolyte 32, and the oxide particles 33. In Figure 2, ions move from solid electrolyte particle 31a to solid electrolyte particle 31c. When there is no electrolyte 32 and oxide particles 33, the ions move along path R3, but when there is electrolyte 32 and oxide particles 33, they move along path R4, which is shorter than path R3 and passes through the electrolyte 32.

[0026] With the above configuration, in the electrolyte layer 30, ions can move through the electrolyte 32 adsorbed on the oxide particles 33 in contact with the solid electrolyte particles 31, and the distance the ions move can be shortened. As a result, the semi-solid battery 1 can facilitate ion movement even with a reduced amount of electrolyte 32 (i.e., reduce the cell's resistance). Figure 3 shows the cell's resistance as a function of the electrolyte volume. The horizontal axis of Figure 3 represents the electrolyte volume, and the vertical axis represents the cell's resistance. As shown in Figure 3, when the electrolyte volume is L, the cell's resistance in a semi-solid battery 1 without oxide particles 33 is V1, but the cell's resistance in a semi-solid battery 1 containing oxide particles 33 is V2, which is lower than V1.

[0027] Furthermore, in the vicinity of the oxide particles 33, the melting point of the electrolyte 32 decreases and the ionic conductivity increases, so the semi-solid battery 1 can suppress the decrease in charge and discharge rates even at low temperatures. Figure 4 shows the input and output of the semi-solid battery 1 as a function of temperature. The horizontal axis of Figure 4 shows the temperature inside the semi-solid battery 1, and the vertical axis shows the input and output of the semi-solid battery 1. For example, the input is the amount of charge per unit time, and the output is the amount of discharge per unit time. As shown in Figure 4, the input and output of the semi-solid battery 1 containing oxide particles 33 (solid line) do not decrease at low temperatures compared to the input and output of the semi-solid battery 1 without oxide particles 33 (dashed line). Specifically, at temperature T2, the difference between the solid line and the dashed line is difference D2, but at temperature T1, which is lower than temperature T2, the difference between the solid line and the dashed line is difference D1, which is greater than difference D2.

[0028] In the electrolyte layer 30, the more uniformly the oxide particles 33 adsorbing the electrolyte 32 are dispersed, the less electrolyte 32 can be used. Furthermore, in the electrolyte layer 30, using larger metal elements as oxide particles 33 makes it easier to uniformly disperse the oxide particles 33. However, even if oxide particles 33 are included in the electrolyte layer 30, uniform dispersion of the oxide particles 33 is not guaranteed. Moreover, since oxide particles 33 are inert, increasing the amount of oxide particles 33 increases the proportion of inert substances in the electrolyte layer 30, and thus the energy density decreases.

[0029] Therefore, the electrolyte layer 30 may contain oxide particles 33 with a particle size smaller than that of the solid electrolyte particles 31, which are coated on the surface of the solid electrolyte particles 31. The surface of the solid electrolyte particles 31 coated with oxide particles 33 may include areas coated with oxide particles 33 and areas not coated with oxide particles 33. In other words, the semi-solid battery 1 may be assembled by storing a plurality of solid electrolyte particles 31, each having oxide particles 33 pre-coated on a portion of its surface, in the electrolyte layer 30.

[0030] With the above configuration, the probability of uniformly dispersing the oxide particles 33 in the electrolyte layer 30 can be increased. As a result, the electrolyte layer 30 can contain an appropriate amount of oxide particles 33 for uniform dispersion, thus suppressing a decrease in energy density. Furthermore, by uniformly dispersing the oxide particles 33, the electrolyte solution 32 can be uniformly dispersed, so in the electrolyte layer 30, the electrolyte solution 32 can be brought closer to each solid electrolyte particle 31, thereby reducing the amount of electrolyte solution 32. As a result, in the electrolyte layer 30, ions can move more easily even with a reduced amount of electrolyte solution 32.

[0031] Figure 5 shows a solid electrolyte particle 31 coated with oxide particles 33. Figure 5 shows the solid electrolyte particle 31, the electrolyte 32, and a plurality of oxide particles 33. In Figure 5, for the sake of simplicity, a plurality of oxide particles 33 coated on one outer circumference of the solid electrolyte particle 31 are shown, and oxide particles 33a and oxide particles 33b are labeled with reference numerals.

[0032] As shown in Figure 5, the electrolyte layer 30 includes, for example, a predetermined number or less of oxide particles 33 coated on the surface of solid electrolyte particles 31 at predetermined intervals W. The predetermined number is, for example, 16 on one outer circumference or surface of the solid electrolyte particles 31. The predetermined interval W is the value obtained by dividing the length of the outer circumference of the solid electrolyte particles 31 by the number of oxide particles 33 arranged on one outer circumference of the solid electrolyte particles 31. With this configuration, regions where ions cannot move (regions coated with oxide particles 33) on the solid electrolyte particles 31 can be dispersed, making it easier for ions to move.

[0033] The volume of oxide particles 33 coated onto the solid electrolyte particles 31 may be less than a predetermined percentage of the volume of the solid electrolyte particles 31. The predetermined percentage is, for example, a fixed value of 1% to 2%. Specifically, if the radius of the solid electrolyte particle 31 is 10 μm and the radius of the oxide particle 33 is 1 μm, the volume of one oxide particle 33 is 0.1% of the volume of one solid electrolyte particle 31. Therefore, if the predetermined percentage is 2%, each solid electrolyte particle 31 will be coated with fewer than 20 oxide particles 33. With this configuration, the volume of the oxide particles 33 can be prevented from becoming unnecessarily large, and thus the semi-solid battery 1 can suppress a decrease in energy density.

[0034] <First variation> In the above description, a configuration in which oxide particles 33 are coated on solid electrolyte particles 31 contained in the electrolyte layer 30 has been illustrated, but the invention is not limited to this. In the semi-solid battery 1, the positive electrode layer 10 may include oxide particles 33 coated on the surface of the positive electrode active material 12, and the negative electrode layer 20 may include oxide particles 33 coated on the surface of the negative electrode active material 22. Furthermore, in the positive electrode layer 10, there may be an electrolyte 32 between adjacent positive electrode active material 12s, and in the negative electrode layer 20, there may be an electrolyte 32 between adjacent negative electrode active material 22s.

[0035] With this configuration, ions can move through the electrolyte 32 adsorbed on the oxide particles 33 in both the positive electrode layer 10 and the negative electrode layer 20. As a result, in the semi-solid battery 1, ion movement can be promoted more effectively than if the oxide particles 33 were limited to coating only the solid electrolyte particles 31, thus enabling a higher output.

[0036] <Second variation> In the above description, a configuration in which the solid electrolyte particles 31 are included in the electrolyte layer 30 has been illustrated, but the explanation is not limited to this. The solid electrolyte particles 31 may also be included in at least one of the positive electrode layer 10 and the negative electrode layer 20. Furthermore, the surface of the solid electrolyte particles 31 may be coated with oxide particles 33.

[0037] <Effects of Semi-Solid Battery 1> As described above, the semi-solid battery 1 includes a positive electrode layer 10 comprising a positive electrode current collector 11 and a positive electrode active material 12, a negative electrode layer 20 comprising a negative electrode current collector 21 and a negative electrode active material 22, and an electrolyte layer 30 provided between the positive electrode layer 10 and the negative electrode layer 20, with a fluid electrolyte 32 between adjacent solid electrolyte particles 31. The electrolyte layer 30 includes oxide particles 33 that are in contact with the solid electrolyte particles 31 and adsorb the electrolyte 32.

[0038] With the semi-solid battery 1 configured in this way, in the electrolyte layer 30, the oxide particles 33 adsorbed by the electrolyte 32 are dispersed in contact with each solid electrolyte particle 31, making it easier for ions to move even with a small amount of electrolyte 32. Furthermore, as shown in Figure 5, the oxide particles 33 can be uniformly dispersed by coating the surface of the solid electrolyte particles 31 with oxide particles 33 at predetermined intervals. As a result, in the semi-solid battery 1, the electrolyte 32 attached to the oxide particles 33 can be uniformly dispersed, making it easier to reduce the amount of electrolyte 32.

[0039] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of its gist. For example, all or part of the apparatus can be configured by functionally or physically distributing and integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combinations are combined with the effects of the original embodiments. [Explanation of symbols]

[0040] 1 Semi-solid battery 10 Positive electrode layer 11 Positive electrode current collector 12 Cathode active material 20 Negative electrode layer 21 Negative electrode current collector 22 Negative electrode active material 30 Electrolyte layer 31 Solid electrolyte particles 31a Solid electrolyte particles 31b Solid electrolyte particles 31c solid electrolyte particles 32 Electrolyte 33 Acid particles 33a acid particles 33b acid particles 34. Gap

Claims

1. A positive electrode layer containing a positive electrode current collector and a positive electrode active material, A negative electrode layer containing a negative electrode current collector and a negative electrode active material, An electrolyte layer is provided between the positive electrode layer and the negative electrode layer, and has a fluid electrolyte between adjacent solid electrolyte particles. It has, The electrolyte layer includes oxide particles that are in contact with the solid electrolyte particles and adsorb the electrolyte. Semi-solid battery.

2. The electrolyte layer comprises a plurality of solid electrolyte particles, a plurality of oxide particles, a void surrounded by the plurality of solid electrolyte particles, and the electrolyte located in a portion of the void. The semi-solid battery according to claim 1.

3. The electrolyte layer includes oxide particles with a particle size smaller than that of the solid electrolyte particles, which are coated on the surface of the solid electrolyte particles. The semi-solid battery according to claim 1.

4. The electrolyte layer includes a predetermined number or less of oxide particles coated on the surface of the solid electrolyte particles at predetermined intervals. The semi-solid battery according to claim 3.

5. The surface of the solid electrolyte particles includes a region coated with the oxide particles and a region not coated with the oxide particles. The semi-solid battery according to claim 3.

6. The oxide particles include zirconia oxide or tungsten dioxide. The semi-solid battery according to claim 1.

7. The positive electrode layer includes the oxide particles coated on the surface of the positive electrode active material, and the negative electrode layer includes the oxide particles coated on the surface of the negative electrode active material. The semi-solid battery according to claim 1.

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