All solid state battery and manufacturing method

Abstract

An embodiment all solid state battery includes a sulfide-based solid electrolyte layer, a negative electrode comprising a negative active material layer stacked on a first surface of the solid electrolyte layer and a negative buffer layer stacked on a first surface of the negative active material layer, and a positive electrode comprising a positive active material layer stacked on a second surface of the solid electrolyte layer and a positive buffer layer stacked on a second surface of the positive active material layer.

Claims

1. An all solid state battery comprising: a sulfide-based solid electrolyte layer; a negative electrode comprising: a negative active material layer disposed on a first surface of the solid electrolyte layer; a negative buffer layer disposed on a first surface of the negative active material layer, the negative buffer layer comprising a mixture of a first sulfide-based material, a first conductive material, and a second binder, wherein the negative buffer layer has a different composition than the negative active material layer; a negative primer layer disposed on a first surface of the negative buffer layer, wherein the negative buffer layer has a degree of softness that is higher than that of the negative primer layer; and a negative current collector layer having a second surface disposed on a first surface of the negative primer layer, the second surface of the negative current collector layer having a surface roughness; and a positive electrode comprising: a positive active material layer disposed on a second surface of the solid electrolyte layer; a positive buffer layer disposed on a second surface of the positive active material layer the positive buffer layer comprising a mixture of the first sulfide-based material, the first conductive material, and the second binder without an active material, wherein the positive buffer layer has a different composition than the positive active material layer; a positive primer layer disposed on a second surface of the positive buffer layer, wherein the positive buffer layer has a degree of softness that is higher than that of the positive primer layer; and a positive current collector layer having a first surface disposed on a second surface of the positive primer layer, the first surface of the positive current collector layer having a surface roughness.

2. The all solid state battery of claim 1, wherein the negative primer layer comprises a mixture of a carbon-based conductive material and a first binder; and wherein the negative active material layer comprises a mixture of a second sulfide-based material, a negative electrode active material, a second conductive material, and a third binder, wherein the negative active material layer is in contact with the solid electrolyte layer.

3. The all solid state battery of claim 1, wherein the negative current collector layer comprises at least one of copper, stainless steel, titanium, iron, or nickel.

4. The all solid state battery of claim 2, wherein the mixture of the carbon-based conductive material and the first binder of the negative primer layer has a ratio of 7:3 to 9-5:0.5.

5. The all solid state battery of claim 1, wherein the mixture of the negative buffer layer comprises the first sulfide-based material in a range of 60 wt % or more and 90 wt % or less, the first conductive material in a range of 9 wt % or more and 30 wt % or less, and the second binder in a range of 1 wt % or more and 10 wt % or less, based on 100 wt % of a total weight.

6. The all solid state battery of claim 1, wherein the negative buffer layer has a same ionic conductivity and electronic conductivity as the negative active material layer.

7. The all solid state battery of claim 2, wherein the mixture of the negative active material layer comprises the second sulfide-based material in a range of 8 wt % to 30 wt %, the negative active material layer in a range of 60 wt % to 90 wt %, the second conductive material in a range of 1 wt % to 10 wt %, and the third binder in a range of 1 wt % to 10 wt %, based on 100 wt % of a total weight.

8. The all solid state battery of claim 1, wherein the positive primer layer comprises a mixture of a carbon-based conductive material and a first binder; and wherein the positive active material layer comprises a mixture of a second sulfide-based material, a positive electrode active material, a second conductive material, and a third binder, wherein the positive active material layer is in contact with the solid electrolyte layer.

9. The all solid state battery of claim 7, wherein the positive current collector layer comprises at least one of stainless steel, titanium, iron, nickel, aluminum, or chromium.

10. The all solid state battery of claim 8, wherein the mixture of the carbon-based conductive material and the first binder of the positive primer layer has a ratio of 7:3 to 9-5:0.5.

11. The all solid state battery of claim 1, wherein the mixture of the positive buffer layer comprises the first sulfide-based material in a range of 60 wt % or more and 90 wt % or less, the first conductive material in a range of 9 wt % or more and 30 wt % or less, and the second binder in a range of 1 wt % or more and 10 wt % or less, based on 100 wt % of a total weight.

12. The all solid state battery of claim 1, wherein the positive buffer layer has a same ionic conductivity and electronic conductivity as the positive active material layer.

13. The all solid state battery of claim 8, wherein the mixture of the positive active material layer comprises the second sulfide-based material in a range of 8 wt % to 30 wt %, the positive active material layer in a range of 60 wt % to 90 wt %, the second conductive material in a range of 1 wt % to 10 wt %, and the third binder in a range of 1 wt % to 10 wt %, based on 100 wt % of a total weight.

14. A method of manufacturing the all solid state battery of claim 1, the method comprising: forming the negative electrode; forming the sulfide-based solid electrolyte layer on a second surface of the negative electrode; forming the positive electrode and bonding the positive electrode to the second surface of the solid electrolyte layer.

15. The method of claim 14, wherein forming the negative electrode comprises: forming the surface roughness on the second surface of a negative current collector through a surface treatment; forming the negative primer layer on the negative current collector through wet coating; forming the negative buffer layer on the negative primer layer through wet coating; forming the negative active material layer on the negative buffer layer; and rolling the negative current collector, the negative primer layer, the negative buffer layer, and the negative active material layer which are stacked.

16. The method of claim 15, wherein the sulfide-based solid electrolyte layer is formed on the second surface of the negative electrode through wet coating.

17. The method of claim 14, wherein forming the positive electrode comprises: forming surface roughness on the second surface of a positive current collector through a surface treatment; forming the positive primer layer on a first surface of on the positive current collector through wet coating; forming the positive buffer layer on the positive primer layer; forming the positive active material layer on the positive buffer layer; and rolling the positive current collector, the positive primer layer, the positive buffer layer, and the positive active material layer which are stacked.

18. The method of claim 14, wherein bonding the positive electrode comprises: inverting the positive electrode in a vertical direction and contacting the sulfide-based solid electrolyte layer with the positive active material layer of the positive electrode; and rolling the negative electrode, the sulfide-based solid electrolyte layer, and the positive electrode.

19. An all solid state battery comprising: a positive current collector layer; a positive primer layer overlying the positive current collector layer; a positive buffer layer overlying the positive primer layer; a positive active material layer overlying the positive buffer layer; a sulfide-based solid electrolyte layer overlying the positive active material layer; a negative active material layer overlying the sulfide-based solid electrolyte layer; a negative buffer layer overlying the negative active material layer; a negative primer layer overlying the negative buffer layer; and a negative current collector layer overlying the negative primer layer; wherein the negative buffer layer comprises a mixture of a first sulfide-based material, a first conductive material, and a second binder; wherein the mixture of the negative buffer layer does not include any active material; wherein the negative buffer layer has a degree of softness that is higher than that of the negative primer layer; wherein a surface of the negative current collector layer adjacent the negative primer layer has a surface roughness; wherein the positive buffer layer comprises a mixture of the first sulfide-based material, the first conductive material, and the second binder; wherein the positive buffer layer has a degree of softness that is higher than that of the positive primer layer; wherein first surface of the positive current collector layer adjacent the negative primer has a surface roughness; wherein the negative primer layer comprises a mixture of a carbon-based conductive material and a first binder; wherein the mixture of the positive buffer layer does not include any active material; wherein the negative active material layer comprises a mixture of a second sulfide-based material, a negative electrode active material, a second conductive material, and a third binder, wherein the negative active material layer is in contact with the solid electrolyte layer; wherein the negative active material layer comprises the second sulfide-based material in a range of 8 wt % to 30 wt %, the negative active material layer in a range of 60 wt % to 90 wt %, the second conductive material in a range of 1 wt % to 10 wt %, and the third binder in a range of 1 wt % to 10 wt %, based on 100 wt % of a total weight.

20. An all solid state battery comprising: a positive current collector layer; a positive primer layer overlying the positive current collector layer; a positive buffer layer overlying the positive primer layer; a positive active material layer overlying the positive buffer layer; a sulfide-based solid electrolyte layer overlying the positive active material layer; a negative active material layer overlying the sulfide-based solid electrolyte layer; a negative buffer layer overlying the negative active material layer; a negative primer layer overlying the negative buffer layer; and a negative current collector layer overlying the negative primer layer; wherein the negative buffer layer comprises a mixture of a first sulfide-based material, a first conductive material, and a second binder; wherein the negative buffer layer has a degree of softness that is higher than that of the negative primer layer; wherein the mixture of the negative buffer layer does not include any active material; wherein a surface of the negative current collector layer adjacent the negative primer layer has a surface roughness; wherein the positive buffer layer comprises a mixture of the first sulfide-based material, the first conductive material, and the second binder; wherein the positive buffer layer has a degree of softness that is higher than that of the positive primer layer; wherein the mixture of the positive buffer layer does not include any active material; wherein first surface of the positive current collector layer adjacent the negative primer layer has a surface roughness; wherein the negative buffer layer has a same ionic conductivity and electronic conductivity as the negative active material layer; and wherein the positive buffer layer has a same ionic conductivity and electronic conductivity as the positive active material layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a schematic view showing a cross-sectional structure of an all solid state battery according to an embodiment of the present invention.

(2) FIG. 2 schematically illustrates a cross-sectional structure of a negative electrode of an all solid state battery according to an embodiment of the present invention.

(3) FIG. 3 schematically illustrates a cross-sectional structure of a positive electrode of an all solid state battery according to an embodiment of the present invention.

(4) FIG. 4 to FIG. 11 illustrate views sequentially showing a manufacturing method of an all solid state battery according to an embodiment of the present invention.

(5) The following elements may be used in connection with the drawings to describe embodiments of the present invention. 1: all solid state battery 10: solid electrolyte layer 20: negative electrode 21: negative current collector 23: negative primer layer 25: negative buffer layer 27: negative active material layer 30: positive electrode 31: positive current collector 33: positive primer layer 35: positive buffer layer 37: positive active material layer

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(6) The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

(7) Parts that are irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals designate like elements throughout the specification.

(8) FIG. 1 illustrates a schematic view showing a cross-sectional structure of an all solid state battery according to an embodiment of the present invention, FIG. 2 schematically illustrates a cross-sectional structure of a negative electrode of an all solid state battery according to an embodiment of the present invention, and FIG. 3 schematically illustrates a cross-sectional structure of a positive electrode of an all solid state battery according to an embodiment of the present invention.

(9) Referring to FIG. 1, the all solid state battery 1 according to the embodiment of the present invention includes a sulfide-based solid electrolyte layer 10, a negative electrode 20, and a positive electrode 30.

(10) The negative electrode 20 is stacked on a first surface of the solid electrolyte layer 10, and the positive electrode 30 is stacked on a second surface thereof.

(11) For example, based on the solid electrolyte layer 10, the negative electrode 20 may be stacked at a lower side, and the positive electrode 30 may be stacked at an upper side.

(12) In an embodiment of the present invention, the left and right, front and rear, and up and down directions are set based on the drawing, and a portion facing an upper side is defined as an upper portion, an upper end, an upper surface, and an upper side portion, and a portion facing a lower side will be defined as a lower portion, a lower end, a lower surface, and a lower end portion.

(13) The definition of the reference direction as described above is a relative meaning, and the direction may vary depending on the reference position of the all solid state battery 1 of embodiments of the present invention, and the reference direction described above is not necessarily limited to the reference direction of the present embodiment.

(14) In an embodiment of the present invention, the solid electrolyte layer 10 may be formed of a sulfide-based material including a lithium sulfide-based compound or an argyrodite-based compound.

(15) This has an advantage that the sulfide-based material applied to the solid electrolyte layer 10 has a superior soft characteristic compared to an oxide-based material, and is suitable for a structural characteristic of the all solid state battery 1 according to the embodiment of the present invention.

(16) A material having ionic conductivity of 1*10.sup.−3 S/cm or more may be used for the solid electrolyte layer 10.

(17) In addition, the solid electrolyte layer 10 may have a particle size (average diameter of each grain constituting the powder) in a range of 0.1 μm or more and 10 μm or less.

(18) The solid electrolyte layer 10 may have a density that is set in a range of 0.1 g/cm.sup.3 or more and 1 g/cm.sup.3 or less.

(19) The solid electrolyte layer 10 may be formed to have a thickness of 50 μm or more and 100 μm or less.

(20) Referring to FIG. 2, in an embodiment of the present invention, the negative electrode 20 includes a negative current collector 21, a negative primer layer 23, a negative buffer layer 25, and a negative active material layer 27.

(21) The negative current collector 21 may include at least one of copper, stainless steel, titanium, iron, and nickel.

(22) The negative current collector 21 has surface roughness formed on an upper surface thereof.

(23) The surface roughness refers to a degree of fine irregularities generated on the surface.

(24) Such surface roughness may be formed through plasma surface treatment or corona surface treatment.

(25) The negative current collector 21 may have a thickness of 15 μm or more and 20 μm or less.

(26) In addition, the negative primer layer 23 is formed on an upper surface of the negative current collector 21.

(27) The negative primer layer 23 may be formed of a mixture of a carbon-based conductive material and a binder.

(28) For example, the negative primer layer 23 can be formed by mixing a conductive material and a binder at a ratio of 7:3 to 9.5:0.5.

(29) The negative primer layer 23 may be formed to have a thickness of 1 μm or less.

(30) The negative buffer layer 25 is formed on an upper surface of the negative primer layer 23.

(31) The negative buffer layer 25 may be formed by mixing a sulfide-based material, a conductive material, and a binder.

(32) For example, the negative buffer layer 25 may be formed of a mixture of a sulfide-based material that is set in a range of 60 wt % or more and go wt % or less, a conductive material that is set in the range of 9 wt % or more and 30 wt % or less, and a binder that is set in a range of 1 wt % or more and 10 wt % or less, based on 100 wt % of a total weight.

(33) The negative buffer layer 25 may have the same ionic conductivity and electronic conductivity as those of the negative active material layer 27.

(34) For example, the negative buffer layer 25 may have ionic conductivity that is set in a range of 1 mS/cm or more and 9.99*10.sup.−9 S/cm or less.

(35) In addition, the negative buffer layer 25 has softness that is higher than that of the negative primer layer 23.

(36) The negative buffer layer 25 may be formed to have a thickness of 20 μm or more and 100 μm or less.

(37) The negative active material layer 27 is formed on an upper surface of the negative buffer layer 25.

(38) The negative active material layer 27 may be formed of a mixture of a sulfide-based material, a negative active material, a conductive material, and a binder.

(39) For example, the negative active material layer 27 may be formed of a mixture of a sulfide-based material in a range of 8 wt % to 30 wt %, a negative active material in a range of 60 wt % to 90 wt %, a conductive material in a range of 1 wt % to 10 wt %, and a binder in a range of 1 wt % to 10 wt %, based on 100 wt % of a total weight.

(40) The negative active material layer 27 may be formed to have a thickness of 20 μm or more and 100 μm or less.

(41) The solid electrolyte layer 10 is disposed on an upper surface of the negative active material layer 27.

(42) In addition, the positive electrode 30 is formed on an upper surface of the solid electrolyte layer 10, and is formed to be symmetrical with the negative electrode 20 with respect to the solid electrolyte layer 10.

(43) Referring to FIG. 3, the positive electrode 30 is formed in the same manner as the negative electrode 20, and then is inverted in a vertical direction to be stacked on an upper surface of the solid electrolyte layer 10, but a structure will be described based on a direction shown in FIG. 1.

(44) Accordingly, the positive electrode 30 will be described starting with the positive current collector 31 positioned at an outermost upper portion thereof.

(45) In the present embodiment, the positive electrode 30 includes the positive current collector 31, a positive primer layer 33, a positive buffer layer 35, and a positive active material layer 37.

(46) The positive current collector 31 may include at least one of stainless steel, titanium, iron, nickel, aluminum, and chromium.

(47) The positive current collector 31 has surface roughness formed on a lower surface thereof.

(48) The surface roughness on the positive current collector 31 is the same as the surface roughness on the negative current collector 21.

(49) The positive current collector 31 may have a thickness of 15 μm or more and 20 μm or less.

(50) In addition, the positive primer layer 33 is formed on a lower surface of the positive current collector 31.

(51) The positive primer layer 33 may be formed of a mixture of a carbon-based conductive material and a binder.

(52) For example, the positive primer layer 33 can be formed by mixing a conductive material and a binder at a ratio of 7:3 to 9.5:0.5.

(53) The positive primer layer 33 may be formed to have a thickness of 1 μm or less.

(54) The positive buffer layer 35 is formed on a lower surface of the positive primer layer 33.

(55) The positive buffer layer 35 may be formed by mixing a sulfide-based material, a conductive material, and a binder.

(56) For example, the positive buffer layer 35 may be formed of a mixture of a sulfide-based material that is set in a range of 60 wt % or more and go wt % or less, a conductive material that is set in the range of 9 wt % or more and 30 wt % or less, and a binder that is set in a range of 1 wt % or more and 10 wt % or less, based on 100 wt % of a total weight.

(57) The positive buffer layer 35 may have the same ionic conductivity and electronic conductivity as those of the positive active material layer 37.

(58) For example, the positive buffer layer 35 may have ionic conductivity that is set in a range of 1 mS/cm or more and 9.99*10.sup.−9 S/cm or less.

(59) In addition, the positive buffer layer 35 has softness that is higher than that of the positive primer layer 33.

(60) The positive buffer layer 35 may be formed to have a thickness of 1 μm or more and 5 μm or less.

(61) The positive active material layer 37 is formed on a lower surface of the positive buffer layer 35.

(62) The positive active material layer 37 may be formed of a mixture of a sulfide-based material, a positive active material, a conductive material, and a binder.

(63) For example, the positive active material layer 37 may be formed of a mixture of a sulfide-based material in a range of 8 wt % to 30 wt %, a positive active material in a range of 60 wt % to go wt %, a conductive material in a range of 1 wt % to 10 wt %, and a binder in a range of 1 wt % to 10 wt %, based on 100 wt % of a total weight.

(64) The positive active material layer 37 may be formed to have a thickness of 20 μm or more and 100 μm or less.

(65) The solid electrolyte layer 10 is disposed on a lower surface of the positive active material layer 37.

(66) A manufacturing method of the all solid state battery configured as described above will be as follows.

(67) FIG. 4 to FIG. 11 illustrate views sequentially showing a manufacturing method of an all solid state battery according to an embodiment of the present invention.

(68) In accordance with the manufacturing method of the all solid state battery, the negative electrode 20 and the positive electrode 30 are separately manufactured, and then the negative electrode 20 and the positive electrode 30 are bonded to a first side and a second side of the solid electrolyte layer 10, respectively.

(69) In this case, the negative electrode 20 is disposed on a lower surface of the solid electrolyte layer 10, and the positive electrode 30 is disposed on an upper surface of the solid electrolyte layer 10.

(70) Accordingly, the positive electrode 30 may be formed to be symmetrical with the negative electrode 20 with respect to the solid electrolyte layer 10 by stacking each material in order, and then by inverting it in a vertical direction and bonding it to the upper surface of the solid electrolyte layer 10.

(71) Referring to FIG. 4, surface roughness is formed on an upper surface of the negative current collector 21 through a surface treatment.

(72) The surface treatment may include a plasma surface treatment or a corona surface treatment.

(73) The plasma surface treatment or corona surface treatment is a process of roughening a surface by irradiating plasma or corona on the upper surface of the negative current collector 21 to change a state of the surface.

(74) This surface treatment is to increase a bonding area depending on the surface roughness.

(75) Referring to FIG. 5, the negative primer layer 23 is formed on the upper surface of the negative current collector 21.

(76) The negative primer layer 23 is formed through wet coating, and the wet coating may include gravure coating and slot die coating, for example.

(77) The negative primer layer 23 may prevent corrosion of the negative current collector 21.

(78) In addition, the negative primer layer 23 is made of a mixture of a carbon-based conductive material and a binder, and electronic conductivity may be improved by the carbon-based conductive material.

(79) Referring to FIG. 6, the negative buffer layer 25 is formed on an upper surface of the negative primer layer 23.

(80) The negative buffer layer 25 is formed through wet coating, and the wet coating may include gravure coating and slot die coating, for example.

(81) The negative buffer layer 25 has softness that is higher than that of the negative primer layer 23.

(82) The negative buffer layer 25 may move ions and electrons, thereby improving capacitance.

(83) Referring to FIG. 7, the negative active material layer 27 is formed on an upper surface of the negative buffer layer 25.

(84) The negative active material layer 27 may have the same ionic conductivity and electronic conductivity as those of the negative buffer layer 25.

(85) Referring to FIG. 8, when the negative current collector 21, the negative primer layer 23, the negative buffer layer 25, and the negative active material layer 27 are stacked as described above, a rolling process is performed.

(86) In this case, the rolling process is performed at a pressure that is set in a range of 0.1 MPa or more and 10 MPa or less.

(87) The negative electrode 20 increases physical cohesion between the negative buffer layer 25 and the negative active material layer 27 during the rolling process due to high softness of the negative buffer layer 25.

(88) Referring to FIG. 9, the solid electrolyte layer 10 is formed on an upper surface of the negative active material.

(89) The solid electrolyte layer 10 is formed through wet coating, and the wet coating may include gravure coating and slot die coating, for example.

(90) Ions may move through the solid electrolyte layer 10.

(91) Next, steps of FIG. 4 to FIG. 8 are repeated to form the positive electrode 30.

(92) That is, surface roughness is formed on an upper surface of the positive current collector 31 through a surface treatment, the positive primer layer 33 is formed on the upper surface of the positive current collector 31, the positive buffer layer 35 is formed on an upper surface of the positive primer layer 33, and the positive active material layer 37 is formed on an upper surface of the positive buffer layer 35.

(93) Referring to FIG. 10, the positive electrode 30 formed as described above is inverted in the vertical direction, and then is stacked on the upper surface of the solid electrolyte layer 10.

(94) In other words, the positive active material layer 37 of the positive electrode 30 is disposed to contact the solid electrolyte layer 10, and is stacked.

(95) Referring to FIG. 11, a rolling process is performed on the negative electrode 20, the solid electrolyte layer 10, and the positive electrode 30 which are stacked.

(96) In this case, the rolling process is performed at a pressure that is set in a range of 0.1 MPa or more and 10 MPa or less.

(97) The all solid state battery 1 may improve binding strength between the negative active material, the solid electrolyte layer 10, and the positive active material through the rolling process.

(98) Accordingly, in accordance with the all solid state battery and a manufacturing method thereof according to the embodiments of the present invention, it is possible to minimize electrode porosity that may occur after a rolling process by applying a negative electrode buffer layer and a positive electrode buffer layer, and maximizing interlayer interfacial adhesion areas.

(99) Thus, in accordance with the all solid state battery and a manufacturing method thereof, ions and electrons may move uniformly at upper and lower portions of an electrode, thereby improving the output and durability.

(100) In addition, in accordance with the all solid state battery and a manufacturing method thereof according to the embodiments of the present invention, it is possible to minimize deformation caused by volume change of the negative active material or positive active material that may occur during charging and discharging, resultantly improving a life characteristic.

(101) While the present invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the following claims.