Positive pole piece, battery cell and lithium ion battery

Abstract

The utility model discloses a positive pole piece, a battery cell and a lithium ion battery, and belongs to the technical field of batteries. According to the positive pole piece, N thinning areas are arranged on a second positive active material layer, N is a positive integer larger than 2, and liquid absorption layers are arranged in the thinning areas; each liquid absorption layer is provided with a first surface deviating from the positive electrode current collector, the second positive electrode active material layer is provided with a second surface deviating from the positive electrode current collector, the sum of the areas of the first surfaces of the N liquid absorption layers is S1, the area of the second surface is S2, and when S1 is larger than or equal to 0.05 S2 and smaller than or equal to 0.2 S2, the liquid absorption layers can improve the liquid absorption and liquid retention capacity of a corner region in the battery cell winding structure, and the battery cell winding structure is more stable. Ion transmission is promoted, so that the lithium precipitation risk is reduced, and the cell performance is maintained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a positive electrode sheet, a battery cell and a lithium ion battery. BACKGROUND

[0002] At present, the battery with a winding structure is usually formed by winding a positive electrode sheet, a separator and a negative electrode sheet, and forms a flat area and a bending area. In the long-term charging and discharging cycle process, the bending area of the battery cell is prone to lithium precipitation, which has a great influence on the safety performance of the battery cell. CONTENT OF THE UTILITY MODEL

[0003] The present application aims to overcome the deficiencies in the prior art and provides a positive electrode sheet, a battery cell and a lithium ion battery. The positive electrode sheet is provided with N thinning areas in the second positive electrode active material layer, N is a positive integer greater than 2, and a liquid absorption layer is arranged in the thinning area. The liquid absorption layer has a first surface facing away from the positive electrode current collector, the second positive electrode active material layer has a second surface facing away from the positive electrode current collector, the sum of the areas of the first surfaces of the N liquid absorption layers is S1, and the area of the second surface is S2. When 0.05S2≤S1≤0.2S2 is satisfied, the liquid absorption layer can improve the liquid absorption and retention capacity of the corner area in the winding structure of the battery cell, promote ion transmission, thereby reducing the risk of lithium precipitation and maintaining the performance of the battery cell.

[0004] To achieve the above-mentioned purpose, in the first aspect of the present application, the present application provides a positive electrode sheet, which comprises a positive electrode current collector, the positive electrode current collector comprises a predetermined bending part and a predetermined flat part arranged alternately, the predetermined bending part connects adjacent predetermined flat parts, and the predetermined bending directions of adjacent predetermined bending parts are opposite, both sides of the predetermined flat part are provided with a first positive electrode active material layer, both sides of the predetermined bending part are provided with a second positive electrode active material layer, the second positive electrode active material layer is provided with N thinning areas, each thinning area is provided with a liquid absorption layer, N is a positive integer greater than 2; the liquid absorption layer has a first surface facing away from the positive electrode current collector, the second positive electrode active material layer has a second surface facing away from the positive electrode current collector, the sum of the areas of the first surfaces of the N liquid absorption layers is S1, the area of the second surface is S2, and 0.05S2≤S1≤0.2S2.

[0005] As an embodiment of the present application, the size of the second positive electrode active material layer in the length direction of the positive electrode sheet is W, the size of the second positive electrode active material layer in the width direction of the positive electrode sheet is L; the size of the liquid absorption layer in the width direction of the positive electrode sheet is y, and the size of the liquid absorption layer in the length direction of the positive electrode sheet is x, wherein y / x=L / W. With this ratio, the improvement of the liquid absorption and retention capacity of the corner area by the liquid absorption layer can be optimized to the greatest extent, and the lithium precipitation in each area of the corner area is uniformly improved.

[0006] As an embodiment of the present application, the first surface is flush with the second surface.

[0007] As an embodiment of the present application, along the thickness direction of the positive electrode tab, the thickness of the second positive electrode active material layer is H, the thickness of the liquid absorption layer is h, and 0.2H≤h≤H. Controlling the thickness of the liquid absorption layer in the range of 0.2H to H can improve the liquid absorption performance of the corner area; setting the liquid absorption layer to satisfy 0.2H≤h<H can also prevent the liquid absorption layer from separating from the second positive electrode active material layer during the expansion process of the corner area of the positive electrode during charging and discharging.

[0008] As an embodiment of the present application, N is 3 to 6, wherein one liquid absorption layer is located in the center area of the second positive electrode active material layer, and the remaining N-1 liquid absorption layers are respectively located in the center area of the N-1 equal division areas of the second positive electrode active material layer.

[0009] As an embodiment of the present application, the liquid absorption layer is a porous material layer, and the porous material can be at least one of a porous carbon material, a porous ceramic, and an organic porous material.

[0010] As an embodiment of the present application, the positive electrode current collector is a metal foil, and the metal foil can be an aluminum foil.

[0011] As an embodiment of the present application, an electrically conductive primer layer is arranged between the first positive electrode active material layer and the positive electrode current collector, and between the second positive electrode active material layer and the positive electrode current collector.

[0012] In a second aspect of the present application, an electric core is provided, comprising a positive electrode tab, a separator, and a negative electrode tab, the separator being arranged between the positive electrode tab and the negative electrode tab, the negative electrode tab, the separator, and the positive electrode tab being sequentially stacked and wound to form a winding structure, the winding structure comprising a flat area and a corner area, the corner area connecting adjacent flat areas, the predetermined flat part being located in the flat area, and the predetermined bending part being located in the corner area.

[0013] As an embodiment of the present application, the number of winding layers of the winding structure is n, the diameter of the innermost corner area in the winding structure is D0, the thickness of the positive electrode tab is h1, the thickness of the negative electrode tab is h2, the thickness of the separator is h3, and in the winding direction of the winding structure, the second positive electrode active material layer width W n,i satisfies the following relationship: W n,i =π×[D0+(n-1)×ΔT] / 2, ΔT=2×(h1+h2+h3).

[0014] The second positive electrode active material layer width W n,osatisfies the following relationship: W n,o = W n,i + π x 2 x h1.

[0015] In a third aspect of the present application, the present application provides a lithium ion battery comprising the battery cell according to the second aspect. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 A cross-sectional structure schematic diagram of the positive electrode plate provided by the present application is shown in the figure;

[0017] Fig. 2 A front view of the positive electrode plate provided by the present application is shown in the figure;

[0018] Fig. 3 A structure schematic diagram of the predetermined bending part of the positive electrode plate according to the embodiment 1 of the present application is shown in the figure.

[0019] In the figure, 1 is a positive current collector, 2 is a first positive active material layer, 3 is a second positive active material layer, and 4 is a liquid absorption layer. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0021] In the present application, the technical features described in an open manner include both the closed technical solutions composed of the listed features and the open technical solutions containing the listed features.

[0022] In the present application, if the first and the second are described for the purpose of distinguishing technical features, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0023] In the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solutions.

[0024] In this application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this application, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0025] Please refer to Figs. 1-3 The positive electrode tab provided by the embodiments of the application comprises a positive electrode current collector 1, the positive electrode current collector 1 comprises predetermined bending parts and predetermined straight parts arranged alternately, the predetermined bending parts are connected to adjacent predetermined straight parts, the predetermined bending directions of adjacent predetermined bending parts are opposite, the two side surfaces of the predetermined straight part are provided with a first positive electrode active material layer 2, and the two side surfaces of the predetermined bending part are provided with a second positive electrode active material layer 3, the second positive electrode active material layer 3 is provided with N thinning zones, each thinning zone is provided with a liquid absorption layer 4, and N is a positive integer greater than 2.

[0026] The predetermined straight part is located in a straight zone in the winding structure of the battery cell, and the predetermined bending part is located in a corner zone in the winding structure of the battery cell. The positive electrode tab provided by the application sets the thinning zone in the second positive electrode active material layer 3 and sets the liquid absorption layer 4 in the thinning zone, so that the liquid absorption and liquid retention capacity of the corner zone in the winding structure of the battery cell can be improved, ion transmission is promoted, the risk of lithium precipitation is reduced, and the performance of the battery cell is maintained.

[0027] In an embodiment, the liquid absorption layer 4 has a first surface facing away from the positive electrode current collector 1, the second positive electrode active material layer 3 has a second surface facing away from the positive electrode current collector 1, the sum of the areas of the first surfaces of the N liquid absorption layers 4 is S1, the area of the second surface is S2, when 0.05S2≤S1≤0.2S2 is satisfied, the liquid absorption and liquid retention performance of the corner zone can be improved by the liquid absorption layer 4, but when S1 is greater than 0.2S2, the increase of the area of the liquid absorption layer 4 has limited effect on the performance, and at the same time, the active material content of the positive electrode tab is reduced.

[0028] The first surface is flush with the second surface.

[0029] In an embodiment, along the thickness direction of the positive electrode tab, the thickness of the second positive electrode active material layer 3 is H, and the thickness of the liquid absorption layer 4 is h, and 0.2H≤h≤H. Controlling the thickness of the liquid absorption layer 4 in the range of 0.2H to H can improve the liquid absorption and liquid retention performance of the corner zone; setting the liquid absorption layer 4 satisfying 0.2H≤h<H can also prevent the liquid absorption layer 4 from separating from the second positive electrode active material layer 3 in the expansion process of the positive electrode corner zone in charging and discharging.

[0030] In an embodiment, N is 3-6, one of the liquid-absorbing layers 4 is located in the center of the second positive electrode active material layer 3, and the other N-1 liquid-absorbing layers 4 are respectively located in the center of N-1 equal parts of the second positive electrode active material layer 3. This distribution of the liquid-absorbing layers 4 can more evenly and stably improve the liquid-absorbing performance of the corner area in the winding structure of the battery cell, and avoid uneven wetting.

[0031] It can be understood that the shape of the liquid-absorbing layer 4 is not particularly limited in the present application. For example, the liquid-absorbing layer 4 can be a cylindrical column, an elliptical column or a polygonal column.

[0032] In an embodiment, the liquid-absorbing layer 4 is a square column, the size of the second positive electrode active material layer 3 in the length direction of the positive electrode sheet is W, the size of the second positive electrode active material layer 3 in the width direction of the positive electrode sheet is L, the size of the liquid-absorbing layer 4 in the width direction of the positive electrode sheet is y, and the size of the liquid-absorbing layer 4 in the length direction of the positive electrode sheet is x, wherein y / x=L / W. With this ratio, the improvement of the liquid-absorbing layer on the liquid-absorbing and liquid-retaining performance of the corner area can be optimized to the greatest extent, and the lithium precipitation in each area of the corner area can be uniformly improved.

[0033] In an embodiment, the liquid-absorbing layer 4 is a porous material layer, and the porous material can be at least one of a porous carbon material, a porous ceramic and an organic porous material. The porous carbon material can be at least one of carbon black, graphite and nano carbon fiber. The porous ceramic can be at least one of alpha-alumina, boehmite and nano silicon dioxide. The organic porous material can be at least one of polyvinylidene fluoride and polyester film.

[0034] The mass percentage of the porous material in the liquid-absorbing layer 4 is 90-98%, and the liquid-absorbing layer 4 further includes a binder. The mass percentage of the binder in the liquid-absorbing layer 4 is 2-10%.

[0035] In an embodiment, the first positive electrode active material layer 2 and the second positive electrode active material layer 3 are of the same or different materials, the thickness of the first positive electrode active material layer 2 is the same as the thickness of the second positive electrode active material layer 3, and the materials include a positive electrode active material, a binder and a conductive agent. The positive electrode active material includes at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, transition metal phosphate and lithium iron phosphate. The conductive agent includes at least one of conductive carbon black, graphite, nano carbon fiber and carbon nanotube. The binder includes at least one of oil-based polyvinylidene fluoride (PVDF) and carboxylated polyvinylidene fluoride (C-PVDF). In the materials, the mass percentage of the positive electrode active material is 96-98%, the mass percentage of the conductive agent is 0.5-3%, and the mass percentage of the binder is 1-2%.

[0036] In an embodiment, the liquid-absorbing layer 4 is a positive electrode active material layer, the porosity of the liquid-absorbing layer 4 is greater than the porosity of the first positive electrode active material layer 2, and the porosity of the liquid-absorbing layer 4 is greater than the porosity of the second positive electrode active material layer 3.

[0037] In an embodiment, the positive electrode current collector 1 is a metal foil, which can be an aluminum foil.

[0038] In an embodiment, an electrically conductive primer layer is arranged between the first positive electrode active material layer 2 and the positive electrode current collector 1 and between the second positive electrode active material layer 3 and the positive electrode current collector 1. The arrangement of the electrically conductive primer layer can enhance the interface between the current collector and the positive electrode active material layer and reduce the direct current resistance of the battery cell.

[0039] The embodiment of the present application also provides a battery cell, which includes a positive electrode sheet, a separator, and a negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet, the separator, and the positive electrode sheet are sequentially and spirally wound to form a spiral structure. The spiral structure includes a flat area and a corner area. The corner area connects adjacent flat areas. A predetermined flat part is located in the flat area, and a predetermined bending part is located in the corner area.

[0040] In an embodiment, the spiral structure has n winding layers. The diameter of the innermost corner area in the spiral structure is D0. The thickness of the positive electrode sheet is h1. The thickness of the negative electrode sheet is h2. The thickness of the separator is h3. In the winding direction of the spiral structure, the width W2 of the second positive electrode active material layer 3 inside the nth corner area is n,i satisfies the following relationship: W2 n,i = π × [D0 + (n-1) × ΔT] / 2, ΔT = 2 × (h1 + h2 + h3).

[0041] The width W2 of the second positive electrode active material layer 3 outside the nth corner area is n,o satisfies the following relationship: W2 n,o = W2 n,i + π × 2 × h1.

[0042] In an embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer arranged on the surface of the negative electrode current collector. The negative electrode current collector can be a copper foil. The negative electrode active material layer can include the following components in the following mass percentages: 96-98% of a negative electrode active material, 0-1% of a conductive agent, 0.5-2% of a binder, and 0.5-2% of a thickening agent. The separator can be a conventional separator.

[0043] The embodiment of the present application also provides a lithium ion battery including the battery cell.

[0044] The inventor has carried out a large number of research experiments in the research experiment process, including designing and preparing different positive electrode plates and lithium ion batteries, and testing the battery performance. Some experimental cases and effect test results are listed below to illustrate the present application:

[0045] Embodiment 1

[0046] Please refer to Figs. 1-3 A lithium ion battery includes a battery core, the battery core includes a positive electrode plate, a separator and a negative electrode plate, the separator is arranged between the positive electrode plate and the negative electrode plate, and the negative electrode plate, the separator and the positive electrode plate are sequentially stacked and wound to form a winding structure. During assembly, the positive electrode plate, the separator and the negative electrode plate are sequentially stacked and wound in the same direction to form a battery core; then an aluminum plastic film is used for packaging, electrolyte is injected, vacuum packaging, formation, shaping are carried out, and a lithium ion battery is prepared.

[0047] The positive electrode plate includes a positive electrode current collector 1, the positive electrode current collector 1 includes a predetermined bending part and a predetermined flat part arranged alternately, the predetermined bending part connects adjacent predetermined flat parts, and the predetermined bending directions of adjacent predetermined bending parts are opposite, both sides of the predetermined flat part are provided with a first positive electrode active material layer 2, both sides of the predetermined bending part are provided with a second positive electrode active material layer 3, the second positive electrode active material layer 3 is provided with five thinning zones, and each thinning zone is provided with a liquid absorption layer 4, one of which is located in the center area of the second positive electrode active material layer 3, and the other four are located in the center areas of the four equal parts of the second positive electrode active material layer 3.

[0048] The size of the second positive electrode active material layer 3 in the length direction of the positive electrode plate is W, and the size of the second positive electrode active material layer 3 in the width direction of the positive electrode plate is L; the size of the liquid absorption layer 4 in the thinning zone of the second positive electrode active material layer 3 in the width direction of the positive electrode plate is y, and the size in the length direction of the positive electrode plate is x; x, y, L, W satisfy the following relationship: y / x=L / W.

[0049] The positive electrode current collector 1 is an aluminum foil.

[0050] Each liquid absorption layer 4 has the same structure and is a cuboid structure; the liquid absorption layer 4 is a porous material layer, and the porous material includes the following components in mass percentage: 98% of carbon black material Super-P and 2% of polyvinylidene fluoride (PVDF).

[0051] The liquid absorption layer 4 has a first surface facing away from the positive electrode current collector 1, the second positive electrode active material layer 3 has a second surface facing away from the positive electrode current collector 1, the sum of the areas of the first surfaces of the N liquid absorption layers 4 is S1, the area of the second surface is S2, S1=0.15S2, and the first surface is flush with the second surface.

[0052] The thickness of the second positive active material layer 3 is H and the thickness of the liquid-absorbing layer 4 is h along the thickness direction of the positive electrode tab, h = 0.5H.

[0053] The first positive active material layer 2 and the second positive active material layer 3 are of the same material, which includes the following components in mass percentage: 97% lithium cobaltate, 2% polyvinylidene fluoride (PVDF) and 1% conductive agent (Super-P / CNT).

[0054] The separator is a PP / PE / PP composite separator (Celgard 2325).

[0055] The negative electrode tab includes a negative electrode current collector, the two side surfaces of the negative electrode current collector are provided with a negative electrode active material layer, the negative electrode current collector is a copper foil, and the negative electrode active material layer can include the following components in mass percentage: 97% graphite, 1% butadiene-styrene latex and 2% carboxymethyl cellulose.

[0056] The winding structure includes a flat area and a corner area, the corner area connects adjacent flat areas, the predetermined flat part is located in the flat area, and the predetermined bending part is located in the corner area; the winding layer number of the winding structure is n, the diameter of the innermost corner area in the winding structure is D0, the thickness of the positive electrode tab is h1, the thickness of the negative electrode tab is h2, the thickness of the separator is h3, and the inner side width W n,i of the nth corner area in the winding direction of the winding structure satisfies the following relationship: W n,i = π × [D0 + (n-1) × ΔT] / 2, ΔT = 2 × (h1 + h2 + h3).

[0057] The outer side width W n,o of the nth corner area satisfies the following relationship: W n,o = W n,i + π × 2 × h1.

[0058] Example 2

[0059] The difference between this embodiment and Example 1 is that in this embodiment, the number of liquid-absorbing layers 4 is 3, one of which is located in the center area of the second positive active material layer 3, and the other two are located in the center areas of the two equal parts of the second positive active material layer 3, S1 = 0.09S2.

[0060] Example 3

[0061] The difference between this embodiment and embodiment 1 is that in this embodiment, the number of liquid absorption layers 4 is 6, one of which is located in the center area of the second positive active material layer 3, and the other 5 liquid absorption layers 4 are respectively located in the center area of the five equal parts of the second positive active material layer 3, S1 = 0.18S2.

[0062] Comparative Example 1

[0063] The difference between this comparative example and embodiment 1 is that in this comparative example, each thinning area is not provided with a liquid absorption layer.

[0064] Performance test

[0065] The lithium ion battery in the above embodiment was subjected to performance test, and the test method was as follows:

[0066] Cycle capacity retention rate: 200 cycles were carried out at room temperature, and the charge-discharge mode was as follows: charging at 3C step to 4.3V, then charging at 1.8C constant current and constant voltage to the charging cutoff voltage, discharging at 1C to the discharge cutoff voltage, and the cycle capacity retention rate was calculated according to the following formula: cycle capacity retention rate = cycle discharge capacity / initial discharge capacity x 100%;

[0067] Thickness growth rate: the thickness of the battery cell in the full charged state was tested before and after the cycle (PPG thickness gauge, pressure 600g), and the thickness growth rate was calculated according to the following formula: thickness growth rate = (1-cycle after cell thickness / cycle before cell thickness) x 100%;

[0068] Corner lithium precipitation degree: the cycled battery cell was disassembled, and the corner lithium precipitation degree was observed, which was divided into: (1) slight lithium precipitation: corner lithium precipitation area <25%; (2) obvious lithium precipitation: corner lithium precipitation area 25%-50%; (3) severe lithium precipitation: corner lithium precipitation area >50%.

[0069] The test results are shown in Table 1 below.

[0070] Table 1

[0071]

[0072]

[0073] The above embodiments of the application are described in detail in combination with the drawings, but the application is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the purpose of the application. In addition, the embodiments of the application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A positive electrode sheet, characterized by, The positive electrode current collector comprises predetermined bending parts and predetermined straight parts arranged alternately, the predetermined bending parts are connected with adjacent predetermined straight parts, the predetermined bending directions of adjacent predetermined bending parts are opposite, both sides of the predetermined straight part are provided with a first positive electrode active material layer, both sides of the predetermined bending part are provided with a second positive electrode active material layer, the second positive electrode active material layer is provided with N thinning zones, each thinning zone is provided with a liquid absorption layer, N is a positive integer greater than 2; the liquid absorption layer has a first surface facing away from the positive electrode current collector, the second positive electrode active material layer has a second surface facing away from the positive electrode current collector, the sum of the areas of the first surfaces of the N liquid absorption layers is S1, the area of the second surface is S2, 0.05S2≤S1≤0.2S2.

2. The cathode sheet of claim 1, wherein, The size of the second positive electrode active material layer in the length direction of the positive electrode tab is W, the size of the second positive electrode active material layer in the width direction of the positive electrode tab is L; the size of the liquid absorption layer in the width direction of the positive electrode tab is y, the size of the liquid absorption layer in the length direction of the positive electrode tab is x, wherein y / x=L / W.

3. The cathode sheet of claim 2, wherein, The first surface is flush with the second surface.

4. The cathode sheet of claim 1, wherein In the thickness direction of the positive electrode tab, the thickness of the second positive electrode active material layer is H, and the thickness of the liquid absorption layer is h, 0.2H≤h≤H.

5. The cathode sheet of claim 1, wherein N is 3-6, one of the liquid absorption layers is located in the center area of the second positive electrode active material layer, and the remaining N-1 liquid absorption layers are respectively located in the center areas of the N-1 equal division zones of the second positive electrode active material layer.

6. An electric cell characterized by The positive electrode tab comprises any one of claims 1-5.

7. The cell of claim 6, wherein, Further comprising a negative electrode tab and a separator, the separator is arranged between the positive electrode tab and the negative electrode tab, the negative electrode tab, the separator and the positive electrode tab are sequentially stacked and wound to form a winding structure, the winding structure comprises a straight area and a corner area, the corner area connects adjacent straight areas, the predetermined straight part is located in the straight area, and the predetermined bending part is located in the corner area.

8. The cell of claim 7, wherein, The winding structure has n layers, the innermost corner region in the winding structure has a diameter D0, the thickness of the positive electrode sheet is h1, the thickness of the negative electrode sheet is h2, the thickness of the separator is h3, and the second positive electrode active material layer width W n,i satisfies the following relationship: W n,i = π × [D0 + (n - 1) × ΔT] / 2, ΔT = 2 × (h1 + h2 + h3).

9. The cell of claim 8, wherein, The second positive electrode active material layer width W outside the nth corner region n,o satisfies the following relationship: W n,o = W n,i + π × 2 × h1.

10. A lithium-ion battery, characterized by, The battery cell comprises any one of claims 6-9.

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