Battery cell and battery

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery. The battery cell comprises a positive pole piece and a negative pole piece; the positive pole piece comprises a positive current collector, a positive active material coating, a first semi-solid electrolyte coating and a first solid electrolyte coating; the negative pole piece comprises a negative current collector, a negative active material coating, a second semi-solid electrolyte coating and a second solid electrolyte coating; the thickness of the first semi-solid electrolyte coating is D2 [mu] m, the thickness of the first solid electrolyte coating is D3 [mu] m, the thickness of the second semi-solid electrolyte coating is D5 [mu] m, and the thickness of the second solid electrolyte coating is D6 [mu] m; 0.2 < D2 / D3 < 0.33; 3 < D5 / D6 < = 5; d2 is smaller than D5, and D3 is larger than D6; the battery cell provided by the invention is beneficial to improving the performance of the battery in a hot box safety performance test and improving the cycle performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cell and a battery. Background Art

[0002] Existing lithium-ion batteries face many challenges in terms of safety and performance optimization. On the one hand, in terms of thermal safety performance, the electrolyte materials of existing batteries have poor thermal stability and are prone to decomposition in high-temperature environments, even causing thermal runaway of the battery. At the same time, due to the lack of effective mechanical protection and isolation measures, it is difficult to suppress the growth of lithium dendrites when the battery is subjected to external force impact or internal short circuit. Once the lithium dendrites pierce the diaphragm, it will cause the battery to short circuit, seriously threatening the safety performance of the battery, making it difficult for the battery to meet the ideal standards in the hot box safety performance test. On the other hand, during the battery charging and discharging process, the transmission rhythm of lithium ions between the positive and negative electrodes has a significant impact on the battery performance. The distribution of the components of the positive and negative electrode sheets of existing batteries is mostly symmetrical. This structure makes the transmission of lithium ions between the positive and negative electrodes lack differentiation, resulting in difficulty in matching the speed of lithium ion deintercalation and embedding at the positive and negative electrodes. During the charging and discharging process, the problem of unbalanced lithium ion transmission is prone to occur, resulting in deterioration of battery performance. Summary of the Invention

[0003] Aiming to solve at least one of the technical problems existing in the prior art, the present invention aims to provide a battery cell and a battery having the battery cell, which helps to improve the performance of the battery in a hot box safety performance test and improve the cycle performance of the battery.

[0004] In order to achieve the above-mentioned objectives, in a first aspect, the present invention provides a battery cell, comprising a positive electrode sheet and a negative electrode sheet; the positive electrode sheet comprises a positive electrode current collector, a positive electrode active material coating, a first semi-solid electrolyte coating and a first solid electrolyte coating, wherein the positive electrode active material coating is arranged on one side or both sides of the positive electrode current collector, the first semi-solid electrolyte coating is arranged on the surface of the positive electrode active material coating away from the positive electrode current collector, and the first solid electrolyte coating is arranged on the surface of the first semi-solid electrolyte coating away from the positive electrode active material coating; the negative electrode sheet comprises a negative electrode current collector, a negative electrode active material coating, a second semi-solid electrolyte coating and a second solid electrolyte coating, The negative electrode active material coating is arranged on one side or both sides of the negative electrode current collector, the second semi-solid electrolyte coating is arranged on the surface of the negative electrode active material coating away from the negative electrode current collector, and the second solid electrolyte coating is arranged on the surface of the second semi-solid electrolyte coating away from the negative electrode active material coating; the thickness of the first semi-solid electrolyte coating is D2μm, the thickness of the first solid electrolyte coating is D3μm, the thickness of the second semi-solid electrolyte coating is D5μm, and the thickness of the second solid electrolyte coating is D6μm; satisfying: 0.2<D2 / D3<0.33; 3<D5 / D6≤5; D2<D5, D3>D6.

[0005] In some embodiments, the thickness of the positive electrode active material coating is D1 μm, satisfying: 8<D1 / (D2+D3)<17; 4.3≤D2+D3≤8.6.

[0006] In some embodiments, the thickness of the negative electrode active material coating is D4 μm, satisfying: 8<D4 / (D5+D6)<17; 4.1≤D5+D6≤8.2.

[0007] In some embodiments, 0.92≤(D2*D5) / (D3*D6)≤1.08.

[0008] In some embodiments, the first semi-solid electrolyte coating includes a first polymer and a first inorganic filler; the first solid electrolyte coating includes a second polymer and a second inorganic filler; wherein, in the first semi-solid electrolyte coating, the mass ratio of the first inorganic filler to the first polymer is w1; in the first solid electrolyte coating, the mass ratio of the second inorganic filler to the second polymer is w2; satisfying: 10% ≤ w1 ≤ 20%; 70% ≤ w2 ≤ 80%.

[0009] In some embodiments, the second semi-solid electrolyte coating includes a third polymer and a third inorganic filler; the second solid electrolyte coating includes a fourth polymer and a fourth inorganic filler; wherein, in the second semi-solid electrolyte coating, the mass ratio of the third inorganic filler to the third polymer is w3; in the second solid electrolyte coating, the mass ratio of the fourth inorganic filler to the fourth polymer is w4; satisfying: 10% ≤ w3 ≤ 20%; 70% ≤ w4 ≤ 80%.

[0010] In some embodiments, w1=w3, w2=w4.

[0011] In some embodiments, the first polymer and the third polymer are each independently selected from at least one of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyvinyl alcohol, and polymethyl methacrylate; and / or, the second polymer and the fourth polymer are each independently selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide, and polyacrylate; and / or, the first inorganic filler, the second inorganic filler, the third inorganic filler, and the fourth inorganic filler are each independently selected from at least one of garnet-type solid electrolytes, perovskite-type solid electrolytes, LIS ICON-type solid electrolytes, and NAS ICON-type solid electrolytes.

[0012] In some embodiments, in the adjacent positive electrode sheet and the negative electrode sheet, a side of the first solid electrolyte coating facing away from the first semi-solid electrolyte coating is adhered to a side of the second solid electrolyte coating facing away from the second semi-solid electrolyte coating.

[0013] In some embodiments, a plurality of first concave holes are provided on a side of the positive electrode active material coating layer facing away from the positive electrode current collector, and at least a portion of the first semi-solid electrolyte coating layer is located in the first concave holes.

[0014] In some embodiments, a plurality of second recesses are provided on a side of the negative electrode active material coating layer facing away from the negative electrode current collector, and at least a portion of the second semi-solid electrolyte coating layer is located in the second recesses.

[0015] In a second aspect, the present invention further provides a battery comprising the battery cell described in any one of the above items.

[0016] Compared with the prior art, the battery cell provided by the present invention has the following advantages:

[0017] (1) By arranging the first semi-solid electrolyte coating between the positive electrode active material coating and the first solid electrolyte coating, and arranging the second semi-solid electrolyte coating between the negative electrode active material coating and the second solid electrolyte coating, the first solid electrolyte coating and the second solid electrolyte coating have high thermal stability, mechanical strength and ionic conductivity, can inhibit dendrite growth, provide mechanical protection and isolation for the surface layer, and help improve the performance of the battery in the hot box safety performance test.

[0018] (2) The first semi-solid electrolyte coating serves as a transition layer connecting the positive electrode active material coating and the first solid electrolyte coating, and the second semi-solid electrolyte coating serves as a transition layer connecting the negative electrode active material coating and the second solid electrolyte coating. The semi-solid electrolyte coating can effectively improve the interface stability of the electrode through its excellent conductivity and mechanical flexibility, and small interface impedance, and avoid the degradation of battery performance due to interface problems.

[0019] (3) By setting the thickness ratio of the first semi-solid electrolyte coating and the first solid electrolyte coating to 0.2<D2 / D3<0.33, the thickness of the first semi-solid electrolyte coating of the positive electrode plate is smaller than the thickness of the first solid electrolyte coating, so that the positive electrode plate uses the solid electrolyte coating as the main functional layer, the positive electrode plate uses the semi-solid electrolyte layer as the secondary functional layer, and the first semi-solid electrolyte coating and the first solid electrolyte coating of the positive electrode plate are asymmetric; by setting the thickness ratio of the second semi-solid electrolyte coating and the second solid electrolyte coating to 3<D5 / D6≤5, the thickness of the second semi-solid electrolyte coating of the negative electrode plate is greater than the thickness of the second solid electrolyte coating, so that the negative electrode plate uses the semi-solid electrolyte coating as the main functional layer, the negative electrode plate uses the solid electrolyte coating as the secondary functional layer, and the second semi-solid electrolyte coating and the second solid electrolyte coating of the negative electrode plate are asymmetric. At the same time, by limiting D2<D5 and D3>D6, the first semi-solid electrolyte coating of the positive electrode plate is The thickness of the semi-solid electrolyte coating is less than the thickness of the second semi-solid electrolyte coating of the negative electrode sheet, and the thickness of the first solid electrolyte coating of the positive electrode sheet is greater than the thickness of the second solid electrolyte coating of the negative electrode sheet; through the combination of 0.2<D2 / D3<0.33; 3<D5 / D6≤5; D2<D5, D3>D6, the positive electrode sheet and the negative electrode sheet are asymmetric in the distribution of the composite functional layer (semi-solid electrolyte coating and solid electrolyte coating). This asymmetry makes the conductivity of the composite functional layer (first semi-solid electrolyte coating and first solid electrolyte coating) on ​​the positive electrode side less than the conductivity of the composite functional layer (second semi-solid electrolyte coating and second semi-solid electrolyte coating) on ​​the negative electrode side, thereby successfully constructing a relatively slow lithium deintercalation path on the positive electrode side and a relatively fast lithium intercalation path on the negative electrode side; during the battery charging and discharging process, this characteristic helps to optimize the transmission rhythm of lithium ions between the positive and negative electrodes, making the migration of lithium ions more orderly, and avoiding the battery performance degradation caused by unbalanced lithium ion transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of a battery cell provided by an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the structure of the positive electrode sheet provided by an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of the structure of the negative electrode sheet provided by an embodiment of the present invention.

[0023] In the figure, 100, positive electrode sheet; 101, positive electrode current collector; 102, positive electrode active material coating; 103, first semi-solid electrolyte coating; 104, first solid electrolyte coating; 1011, first surface; 1012, second surface; 1021, first concave hole;

[0024] 200, negative electrode plate; 201, negative electrode current collector; 202, negative electrode active material coating; 203, second semi-solid electrolyte coating; 204, second solid electrolyte coating; 2011, third surface; 2012, fourth surface; 2021, second concave hole. DETAILED DESCRIPTION

[0025] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0026] In the description of the present invention, it should be understood that the terms "thickness", "upper", "lower", etc., indicating positions or location relationships, are based on the positions or location relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed or operate in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0028] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0029] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as commonly understood by technicians in the technical field to which the present invention belongs; the terms used in the specification of the application in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0030] In the application description, the term "and / or" simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0031] Reference to an "embodiment" in the present invention means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0032] First aspect

[0033] See Figure 1-Figure 3 A preferred embodiment of the present invention provides a battery cell, which includes a positive electrode sheet 100 and a negative electrode sheet 200.

[0034] The positive electrode plate 100 includes a positive electrode current collector 101, a positive electrode active material coating 102, a first semi-solid electrolyte coating 103 and a first solid electrolyte coating 104. The positive electrode active material coating 102 is arranged on one side or both sides of the positive electrode current collector, and the first semi-solid electrolyte coating 103 is arranged between the positive electrode active material coating 102 and the first solid electrolyte coating 104; that is, the first semi-solid electrolyte coating 103 is arranged on the side of the positive electrode active material coating 102 away from the positive electrode current collector 101; the first solid electrolyte coating 104 is arranged on the side of the first semi-solid electrolyte coating 103 away from the positive electrode active material coating 102.

[0035] The negative electrode plate 200 includes a negative electrode current collector 201, a negative electrode active material coating 202, a second semi-solid electrolyte coating 203 and a second solid electrolyte coating 204. The negative electrode active material coating 202 is arranged on one side or both sides of the negative electrode current collector 201, and the second semi-solid electrolyte coating 203 is arranged between the negative electrode active material coating 202 and the second solid electrolyte coating 204; that is, the second semi-solid electrolyte coating 203 is arranged on the side of the negative electrode active material coating 202 away from the negative electrode current collector 201; the second solid electrolyte coating 204 is arranged on the side of the second semi-solid electrolyte coating 203 away from the negative electrode active material coating 202.

[0036] The thickness of the positive electrode active material coating 102 is D1 μm, the thickness of the first semi-solid electrolyte coating 103 is D2 μm, the thickness of the first solid electrolyte coating 104 is D3 μm, the thickness of the negative electrode active material coating 202 is D4 μm, the thickness of the second semi-solid electrolyte coating 203 is D5 μm, and the thickness of the second solid electrolyte coating 204 is D6 μm; satisfying: 0.2<D2 / D3<0.33; 3<D5 / D6≤5; D2<D5, D3>D6.

[0037] Based on this technical solution, by arranging the first semi-solid electrolyte coating 103 between the positive electrode active material coating 102 and the first solid electrolyte coating 104, and arranging the second semi-solid electrolyte coating 203 between the negative electrode active material coating 202 and the second solid electrolyte coating 204, the first solid electrolyte coating 104 and the second solid electrolyte coating 204 have high thermal stability, mechanical strength and ionic conductivity, can inhibit dendrite growth, provide mechanical protection and isolation for the surface layer, and help improve the performance of the battery in the hot box safety performance test.

[0038] Specifically, once dendrites begin to form and attempt to grow, the solid electrolyte coating, with its high mechanical strength, can physically hinder the growth of lithium dendrites. During the growth process, lithium dendrites need to overcome the mechanical resistance of the solid electrolyte coating, which makes it difficult for lithium dendrites to grow rapidly and penetrate into other parts of the battery, thereby inhibiting the further development of dendrites and reducing the risk of battery short circuit due to lithium dendrite growth.

[0039] In the hot box safety performance test, the battery will face the test of a high-temperature environment. Since the solid electrolyte coating has high thermal stability, when the temperature rises, the solid electrolyte coating can better maintain its own structural and performance stability, continue to maintain its protective effect on the inside of the battery, and prevent dangerous situations such as short circuits and thermal runaway caused by high temperatures inside the battery, thereby improving the battery's performance in the hot box safety performance test.

[0040] The first semi-solid electrolyte coating serves as a transition layer connecting the positive electrode active material coating and the first solid electrolyte coating, and the second semi-solid electrolyte coating serves as a transition layer connecting the negative electrode active material coating and the second solid electrolyte coating. The semi-solid electrolyte coating can effectively improve the interface stability of the electrode through its excellent conductivity and mechanical flexibility, and small interface impedance, and avoid battery performance degradation caused by interface problems.

[0041] By setting the thickness ratio of the first semi-solid electrolyte coating and the first solid electrolyte coating to 0.2<D2 / D3<0.33, the thickness of the first semi-solid electrolyte coating of the positive electrode plate is less than the thickness of the first solid electrolyte coating, so that the positive electrode plate uses the solid electrolyte coating as the main functional layer, the positive electrode plate uses the semi-solid electrolyte layer as the secondary functional layer, and the first semi-solid electrolyte coating and the first solid electrolyte coating of the positive electrode plate are asymmetric; by setting the thickness ratio of the second semi-solid electrolyte coating and the second solid electrolyte coating to 3<D5 / D6≤5, the thickness of the second semi-solid electrolyte coating of the negative electrode plate is greater than the thickness of the second solid electrolyte coating, so that the negative electrode plate uses the semi-solid electrolyte coating as the main functional layer, the negative electrode plate uses the solid electrolyte coating as the secondary functional layer, and the second semi-solid electrolyte coating and the second solid electrolyte coating of the negative electrode plate are asymmetric. At the same time, by limiting D2<D5 and D3>D6, the first semi-solid electrolyte of the positive electrode plate is The thickness of the coating is less than the thickness of the second semi-solid electrolyte coating of the negative electrode sheet, and the thickness of the first solid electrolyte coating of the positive electrode sheet is greater than the thickness of the second solid electrolyte coating of the negative electrode sheet; through the combination of 0.2<D2 / D3<0.33; 3<D5 / D6≤5; D2<D5, D3>D6, the positive electrode sheet and the negative electrode sheet are asymmetric in the distribution of the composite functional layer (semi-solid electrolyte coating and solid electrolyte coating). This asymmetry makes the conductivity of the composite functional layer (first semi-solid electrolyte coating and first solid electrolyte coating) on ​​the positive electrode side less than the conductivity of the composite functional layer (second semi-solid electrolyte coating and second semi-solid electrolyte coating) on ​​the negative electrode side, thereby successfully constructing a relatively slow lithium deintercalation path on the positive electrode side and a relatively fast lithium intercalation path on the negative electrode side; during the battery charging and discharging process, this characteristic helps to optimize the transmission rhythm of lithium ions between the positive and negative electrodes, making the migration of lithium ions more orderly, and avoiding the degradation of battery performance due to unbalanced lithium ion transmission.

[0042] By limiting 0.2<D2 / D3<0.33, the thickness of the first solid electrolyte coating is 3 to 5 times the thickness of the first semi-solid electrolyte coating. By limiting 3<D5 / D6≤5, the thickness of the second semi-solid electrolyte coating is 3 to 5 times the thickness of the second solid electrolyte coating.

[0043] The asymmetric lithium deintercalation / intercalation pathway constructed above can effectively inhibit the lithium plating process; since the lithium release on the positive electrode side is relatively slow, it can avoid the rapid and large-scale release of lithium ions from the positive electrode and the disordered deposition on the negative electrode surface to form lithium dendrites; at the same time, the relatively fast lithium intercalation pathway on the negative electrode side can ensure that lithium ions can be more evenly embedded in the negative electrode active material, reducing the excessive aggregation of lithium ions in local areas of the negative electrode, thereby reducing the risk of lithium plating; this not only helps to improve the cycle life of the battery, but also improves the safety of the battery and reduces the possibility of short circuit caused by the growth of lithium dendrites.

[0044] Understandably, Figure 1 The diagram only shows a schematic diagram of a battery cell structure containing one positive electrode sheet 100 and one negative electrode sheet 200. In actual production, the number of positive electrode sheets 100 and negative electrode sheets 200 is not limited to this number, as long as the surfaces of adjacent positive electrode sheets 100 and negative electrode sheets 200 are bonded and connected. After the positive electrode sheets 100 and negative electrode sheets 200 are stacked, a battery cell is prepared through a winding process or a lamination process.

[0045] The positive electrode current collector 101 has a first surface 1011 and a second surface 1012 opposite to each other. The positive electrode active material coating 102 is disposed on the first surface 1011 and / or the second surface 1012 of the positive electrode current collector 101 .

[0046] In this embodiment, the first surface 1011 of the positive electrode current collector 101 is sequentially provided with a positive electrode active material coating 102 , a first semi-solid electrolyte coating 103 and a first solid electrolyte coating 104 .

[0047] In some other embodiments, the second surface 1012 of the positive electrode current collector 101 is sequentially provided with a positive electrode active material coating 102, a first semi-solid electrolyte coating 103 and a first solid electrolyte coating 104, or the first surface 1011 and the second surface 1012 of the positive electrode current collector 101 are sequentially provided with a positive electrode active material coating 102, a first semi-solid electrolyte coating 103 and a first solid electrolyte coating 104.

[0048] The negative electrode current collector 201 has a third surface 2011 and a fourth surface 2012 opposite to each other. The negative electrode active material coating 202 is disposed on the third surface 2011 and / or the fourth surface 2012 of the negative electrode current collector 201 .

[0049] In this embodiment, the third surface 2011 of the negative electrode current collector 201 is sequentially provided with the negative electrode active material coating 202 , the second semi-solid electrolyte coating 203 , and the second solid electrolyte coating 204 .

[0050] In some other embodiments, the third surface 2011 of the negative electrode current collector 201 is sequentially provided with a negative electrode active material coating 202, a second semi-solid electrolyte coating 203 and a second solid electrolyte coating 204, or the third surface 2011 and the fourth surface 2012 of the negative electrode current collector 201 are both sequentially provided with a negative electrode active material coating 202, a second semi-solid electrolyte coating 203 and a second solid electrolyte coating 204.

[0051] The positive electrode current collector 101 may include, but is not limited to, aluminum foil, stainless steel foil, titanium foil, and nickel foil.

[0052] The negative electrode current collector 201 may include, but is not limited to, copper foil, stainless steel foil, nickel foil, and the like.

[0053] The material of the positive electrode active material coating 102 can be at least one selected from lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, nickel cobalt manganese ternary material, and lithium iron phosphate.

[0054] The material of the negative electrode active material coating layer 202 may be at least one selected from graphite, a mixed material of graphite and silicon-carbon, a silicon-carbon material, a silicon-oxygen material, and a hard carbon material.

[0055] In the adjacent positive electrode sheet 100 and negative electrode sheet 200 , a surface of the first solid electrolyte coating 104 facing away from the first semi-solid electrolyte coating 103 is bonded to a surface of the second solid electrolyte coating 204 facing away from the second semi-solid electrolyte coating 203 .

[0056] By laminating and connecting the first solid electrolyte coating 104 of the positive electrode plate 100 with the second solid electrolyte coating 204 of the negative electrode plate 200, this structure replaces the traditional diaphragm; specifically, the function of the traditional diaphragm is to physically isolate the positive electrode and the negative electrode to prevent short circuit, while allowing lithium ions to pass through; the battery cell provided by the present invention has a dense microstructure by laminating and connecting the first solid electrolyte coating 104 and the second solid electrolyte coating 204, and the ion conduction channels are orderly and small in size, allowing only small ions such as lithium ions to pass through, while the active material particles of the positive and negative electrodes and other larger particles that may cause short circuits cannot pass through, thereby achieving effective physical isolation of the positive and negative electrodes.

[0057] The semi-solid electrolyte coating is an in-situ polymerized film in a gel-like state. It has excellent conductivity and mechanical flexibility, small interfacial impedance, and is in direct contact with the positive or negative electrode. It can effectively improve the interface stability of the electrode and avoid battery performance degradation due to interface problems. At the same time, good liquid retention can ensure that the electrolyte is stably present in the battery cell and maintain the normal operation of the battery.

[0058] The solid electrolyte coating is a bonded film with excellent thermal stability, mechanical strength, and ionic conductivity. It can inhibit dendrite growth, reducing the risk of short circuits caused by lithium dendrite growth. Its thermal stability effectively prevents thermal runaway in high-temperature environments, while its mechanical strength protects the integrity of the battery's internal structure from external impacts, enhancing battery safety and providing reliable protection for use in a variety of complex environments. The solid electrolyte coating also acts as a separator, achieving a separator-free design and further improving battery safety.

[0059] In some embodiments, 8<D1 / (D2+D3)<17; 4.3≤D2+D3≤8.6, 8<D4 / (D5+D6)<17; 4.1≤D5+D6≤8.2.

[0060] Preferably, 0.92≤(D2*D5) / (D3*D6)≤1.08; in this way, the relative distribution of the semi-solid electrolyte and the solid electrolyte on the positive electrode side and the negative electrode side can be balanced, so that the lithium deintercalation rate of the positive electrode is more matched with the lithium insertion rate of the negative electrode, thereby improving battery performance.

[0061] Preferably, D2 / D3 and D5 / D6 are inverse numbers of each other, (D2*D5) / (D3*D6)=1.

[0062] In the positive electrode plate 100, the first semi-solid electrolyte coating 103 includes a first polymer, a crosslinker, an electrolyte, a first inorganic filler, and an initiator. The first solid electrolyte coating 104 includes a second polymer, a lithium salt, and a second inorganic filler. In the first semi-solid electrolyte coating 103, the mass ratio of the first inorganic filler to the first polymer is w1; in the first solid electrolyte coating 104, the mass ratio of the second inorganic filler to the second polymer is w2, satisfying the following conditions: 10% ≤ w1 ≤ 20%; and 70% ≤ w2 ≤ 80%.

[0063] w1=(mass of the first inorganic filler / mass of the first polymer)*100%; w2=(mass of the second inorganic filler / mass of the second polymer)*100%.

[0064] Furthermore, the first semi-solid electrolyte coating 103 is prepared from the following raw materials in parts by weight: 85-95 parts of electrolyte, 0.1-0.6 parts of initiator and 0.1-1 parts of first inorganic filler; the raw materials also include a first polymer, and the mass ratio of the first polymer to the first inorganic filler is 1:(0.1-0.2); the raw materials also include a crosslinking agent, and the mass ratio of the first polymer to the crosslinking agent is (0.5-2):1.

[0065] The electrolyte concentration is 0.005mol / L-2.5mol / L; the initiator concentration is 0.001mol / L-1mol / L; and the average particle size of the first inorganic filler is 50nm-2μm.

[0066] Furthermore, in the first solid electrolyte coating 104 , the mass ratio of the lithium salt to the second polymer is 1:4, and the mass ratio of the second polymer to the second inorganic filler is 1:(0.7-0.8).

[0067] The average particle size of the second inorganic filler is 50 nm to 2 μm.

[0068] The first solid electrolyte coating is formed by dispersing the second polymer, lithium salt and second inorganic filler in a dispersant to prepare a colloidal solution, which is then coated on the surface of the first semi-solid electrolyte coating through a casting process.

[0069] In the negative electrode plate 200, the second semi-solid electrolyte coating 203 includes a third polymer, a crosslinker, an electrolyte, a third inorganic filler, and an initiator. The second solid electrolyte coating 204 includes a fourth polymer, a lithium salt, and a fourth inorganic filler. In the second semi-solid electrolyte coating 203, the mass ratio of the third inorganic filler to the first polymer is w3; in the second solid electrolyte coating 204, the mass ratio of the fourth inorganic filler to the fourth polymer is w4. The following conditions are satisfied: 10% ≤ w3 ≤ 20%; 70% ≤ w4 ≤ 80%.

[0070] w3=(mass of the third inorganic filler / mass of the third polymer)*100%; w4=(mass of the fourth inorganic filler / mass of the fourth polymer)*100%.

[0071] Furthermore, the second semi-solid electrolyte coating 203 is prepared from the following raw materials in parts by weight: 85-95 parts of electrolyte, 0.1-0.6 parts of initiator and 0.1-1 parts of third inorganic filler; the raw materials also include a first polymer, and the mass ratio of the first polymer to the third inorganic filler is 1:(0.1-0.2); the raw materials also include a crosslinking agent, and the mass ratio of the first polymer to the crosslinking agent is (0.5-2):1.

[0072] The electrolyte concentration is 0.005 mol / L-2.5 mol / L; the initiator concentration is 0.001 mol / L-1 mol / L; and the average particle size of the third inorganic filler is 50 nm-2 μm.

[0073] Furthermore, in the second solid electrolyte coating 204 , the mass ratio of the lithium salt to the fourth polymer is 1:4, and the mass ratio of the fourth polymer to the fourth inorganic filler is 1:(0.7-0.8).

[0074] The colloidal solution prepared by dispersing the fourth polymer, lithium salt and fourth inorganic filler in a dispersant is coated on the surface of the second semi-solid electrolyte coating through a casting process to form the second solid electrolyte coating.

[0075] In the positive electrode plate 100, by limiting the mass ratio of the first inorganic filler and the first polymer in the first semi-solid electrolyte coating 103 to meet 10%≤w1≤20%, the first inorganic filler is in a relatively small amount, so that the first polymer can dominate the performance of the first semi-solid electrolyte coating 103, giving the first semi-solid electrolyte coating 103 good flexibility; during the battery charging and discharging process, the electrode will expand and shrink in volume due to the insertion and deintercalation of lithium ions, and the coating can effectively adapt to such changes due to its flexibility, avoiding the coating from rupturing due to the change in the electrode volume, and ensuring the stability of the internal structure of the battery; at the same time, the relatively small amount of the first inorganic filler will not excessively affect the distribution and retention of the electrolyte in the coating, meeting the liquid retention requirements, maintaining the stable existence of the electrolyte in the battery, ensuring the normal operation of the battery, and improving the battery cycle life. Similarly, in the negative electrode plate 200, by limiting the mass ratio of the third inorganic filler and the third polymer in the second semi-solid electrolyte coating 203 to satisfy 10%≤w3≤20%, the second semi-solid electrolyte coating 203 can be given good flexibility, maintaining the stable presence of the electrolyte in the battery, ensuring the normal operation of the battery, and improving the battery cycle life.

[0076] In the positive electrode plate 100, by limiting the mass ratio of the second inorganic filler and the second polymer in the first solid electrolyte coating 104 to 70%≤w2≤80%, the second inorganic filler is in a relatively large amount. A large amount of the second inorganic filler works synergistically with the second polymer, lithium salt, and dispersant to enhance the mechanical properties of the coating while ensuring that the coating has excellent conductivity. During daily use, transportation, and storage of the battery, it is inevitable to encounter various external forces. At this time, the first solid electrolyte coating 104, with its high strength brought by its high content of inorganic filler, can provide reliable mechanical protection for the surface of the battery plate and prevent external impact from causing damage to the internal structure. In addition, the high content of inorganic filler helps to improve the isolation performance of the coating, effectively blocking the migration of active substances inside the battery and the invasion of external impurities, maintaining the stability of the internal chemical environment of the battery, reducing the risk of battery failure due to internal substance migration or external impurity interference, and improving the safety and reliability of the battery. Similarly, in the negative electrode plate 200, by limiting the ratio of the mass of the fourth inorganic filler in the second solid electrolyte coating 204 to the fourth polymer to satisfy 70%≤w4≤80%, the risk of battery failure due to internal material migration or external impurity interference can be reduced, thereby improving the safety and reliability of the battery.

[0077] In the positive electrode plate 100, by differentiating the inorganic filler content in the first semi-solid electrolyte coating 103 and the first solid electrolyte coating 104, the performance advantages of the first semi-solid electrolyte coating 103 and the first solid electrolyte coating 104 can be complemented. The first semi-solid electrolyte coating 103 focuses on flexibility protection and liquid retention, while the first solid electrolyte coating 104 focuses on mechanical protection, isolation, and conductivity. The two work together to optimize the performance of the battery plate in multiple aspects. This not only ensures the stability of the battery during the charge and discharge process, but also improves the battery's ability to cope with external environmental changes and mechanical impact, laying a solid foundation for improving the battery's overall performance and enabling the battery to better meet the stringent performance requirements of various application scenarios. Similarly, in the negative electrode plate 200, by differentiating the inorganic filler content in the second semi-solid electrolyte coating 203 and the second solid electrolyte coating 204, the performance advantages of the second semi-solid electrolyte coating 203 and the second solid electrolyte coating 204 can be complemented, enabling the battery to better meet the stringent performance requirements of various application scenarios.

[0078] Illustratively, the first polymer is a porous flexible first polymer, and the porous flexible first polymer may include but is not limited to at least one of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyvinyl alcohol, and polymethyl methacrylate.

[0079] The first inorganic filler may include but is not limited to at least one of: a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a lithium superion conductor (LISICON-type solid electrolyte), and a sodium superion conductor (NASICON-type solid electrolyte).

[0080] The second polymer may include but is not limited to at least one of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide, and polyacrylate.

[0081] The second inorganic filler may include but is not limited to at least one of a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a LISICON-type solid electrolyte, and a NASICON-type solid electrolyte.

[0082] The lithium salt may include but is not limited to at least one of lithium perchlorate, lithium hexafluorophosphate, lithium bis(oxalatoborate), lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl imide), and lithium bis(fluorosulfonyl imide).

[0083] The electrolyte in the present invention includes an electrolyte salt and an organic solvent, wherein the electrolyte salt and the organic solvent are both electrolyte salts and organic solvents already existing in the prior art, and the specific types and compositions of the electrolyte salt and the organic solvent are not subject to specific restrictions.

[0084] The dispersant may include but is not limited to: a polymer dispersant such as polyvinyl pyrrolidone, polyacrylic acid, styrene-maleic acid copolymer, or a small molecule surfactant such as lecithin, Span-85, dimethyl palmitamine, or an inorganic dispersant such as sodium hexametaphosphate, sodium pyrophosphate.

[0085] The cross-linking agent may include, but is not limited to, neopentyl glycol diacrylate, fluoroethylene carbonate, ethylene glycol dimethacrylate, and the like.

[0086] The third polymer is a porous flexible third polymer, and the porous flexible third polymer may include but is not limited to at least one of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyvinyl alcohol, and polymethyl methacrylate.

[0087] The third inorganic filler may include but is not limited to at least one of: a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a LISICON-type solid electrolyte, and a NASICON-type solid electrolyte.

[0088] The fourth polymer may include but is not limited to at least one of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide, and polyacrylate.

[0089] The fourth inorganic filler may include but is not limited to at least one of a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a LISICON-type solid electrolyte, and a NASICON-type solid electrolyte.

[0090] A method for determining the mass ratio of a polymer to an inorganic filler, wherein the method is used to determine the mass ratio of a first polymer to an inorganic filler in a semi-solid electrolyte coating, and the mass ratio of a second polymer to an inorganic filler in a solid electrolyte coating, and the specific steps are as follows:

[0091] Step 1: Sample preparation: Take a complete wound secondary battery cell; disassemble the cell and remove the negative electrode; use a scraper or other appropriate tool to scrape off the semi-solid electrolyte coating (or solid electrolyte coating) on ​​the surface of the electrode as the sample to be tested.

[0092] Step 2: Place the scraped semi-solid electrolyte coating sample (or solid electrolyte coating sample) in a crucible and calcine at high temperature to remove organic components; calcine the sample at high temperature in air (for example, calcine at 500-800°C) to completely decompose and remove the organic polymer components therein; record the thermal weight loss curve during the calcination process, determine the mass loss of the organic polymer by thermogravimetric analysis (TGA), and thus calculate the mass of the organic polymer.

[0093] Step 3: After high-temperature calcination, the substances remaining in the crucible are mainly inorganic particles (including inorganic fillers, lithium salts, etc.), and the inorganic particles are separated and purified; the residue is washed (such as using deionized water or an appropriate solvent) to remove soluble lithium salts and other soluble impurities; after filtering, drying, etc., a pure inorganic particle material is finally obtained; the mass of the obtained inorganic particle material is weighed.

[0094] Step 4: Perform energy dispersive spectrum analysis (EDS) on the separated inorganic particles. EDS elemental analysis confirms the lithium salt content and detects its elemental composition. Based on the elemental analysis results, the lithium salt and other metal elements contained therein are identified and quantitatively analyzed. If the true mass of the inorganic filler needs to be further accurately calculated, the mass of the original inorganic filler can be inferred based on the content of metal elements (such as Al, Zr, Si, etc.).

[0095] Step 5: Calculate the mass ratio of the polymer to the inorganic filler using the mass of the organic polymer measured in step 2 and the mass of the original inorganic filler confirmed in step 4.

[0096] See Figure 2 In the positive electrode sheet 100, a first recessed hole 1021 is formed on the side of the positive active material coating 102 facing away from the positive current collector 101, and the first recessed holes 1021 are multiple in number. By providing multiple first recessed holes 1021 in the positive active material coating 102 and disposing the first semi-solid electrolyte coating 103 on one side of the positive active material coating 102, a portion of the first semi-solid electrolyte coating 103 can be embedded in the first recessed holes 1021 and form a three-dimensional transmission network with the positive active material coating 102. This three-dimensional transmission network facilitates ion diffusion, improves the battery's electrode fluid retention capacity, and improves the battery's cycling performance and lithium plating. For example, the depth of the first recessed holes 1021 can be 30%, 40%, 50%, or the like, of the thickness of the positive active material coating 102.

[0097] Specifically, the three-dimensional transport network can increase the channels for ion transmission and provide more diffusion paths for ions, so that ions can be transmitted more quickly and efficiently between the active material coating and the semi-solid electrolyte coating, thereby helping to speed up the battery's charge and discharge process and improve the battery's rate performance.

[0098] The first semi-solid electrolyte coating 103 has certain viscosity and adsorption properties. When part of the semi-solid electrolyte is embedded in the first recessed hole 1021, the semi-solid electrolyte can fix the electrolyte inside the first recessed hole 1021 and in the three-dimensional transmission network structure through physical adsorption, thereby improving the liquid retention capacity of the battery electrode; the semi-solid electrolyte embedded in the recessed hole can support and protect the electrode, thereby preventing the active material coating from being perforated and causing a reduction in the mechanical strength and material stability of the electrode; at the same time, the three-dimensional transmission network formed by the semi-solid electrolyte and the active material coating has a large specific surface area and can form a stable liquid-solid interface with the electrolyte; in the corner area of ​​the wound battery cell, due to the complex spatial structure, the electrolyte is easy to dry up, and the stable liquid-solid interface of the present invention can increase the contact area between the electrolyte and the electrode, so that the electrolyte is more evenly distributed on the surface of the electrode, reducing the possibility of electrolyte drying up in the corner area, thereby improving the liquid retention capacity of the entire battery electrode.

[0099] The formation of a three-dimensional transport network can make the interface between the electrode and the electrolyte more stable; during the battery charging and discharging process, the semi-solid electrolyte can better adapt to the volume changes of the active material coating, reduce the rupture and peeling of the interface, and thus improve the cycle stability of the battery; at the same time, the stable interface helps to evenly transfer ions, avoid excessive aggregation of ions in local areas, and thus reduce the occurrence of lithium plating.

[0100] Since the three-dimensional transmission network is conducive to ion diffusion, the distribution of lithium ions in the active material coating is more uniform. Therefore, in the corner area of ​​the wound battery cell, this uniform distribution can avoid local overcharge or over-discharge caused by uneven ion distribution, thereby improving the cycle performance of the battery in these areas and reducing the occurrence of lithium plating. The reduction of lithium plating helps prevent the growth of lithium dendrites, avoid the growth of lithium dendrites and cause battery short circuit, and further improve the safety and cycle life of the battery.

[0101] See Figure 3 In the negative electrode plate 200, a second recessed hole 2021 is formed on the side of the negative active material coating 202 facing away from the negative current collector 201, and the second recessed hole 2021 is arranged in a plurality. By providing multiple second recessed holes 2021 in the negative active material coating 202 and disposing the second semi-solid electrolyte coating 203 on one side of the negative active material coating 202, a portion of the second semi-solid electrolyte coating 203 can be embedded in the second recessed holes 2021 and form a three-dimensional transmission network with the negative active material coating 202. This three-dimensional transmission network facilitates ion diffusion, improves the battery plate's fluid retention, and improves the battery's cycling performance and lithium plating. For example, the depth of the second recessed hole 2021 can be 30%, 40%, 50%, or other percentages of the thickness of the negative active material coating 202.

[0102] Second aspect

[0103] The present invention also provides a battery, comprising any one of the above-mentioned battery cells.

[0104] In order to better understand the technical solutions provided by the present invention, the following specific examples are used to illustrate the preparation methods and characteristics of the positive electrode sheet and the negative electrode sheet of the present invention.

[0105] Example 1

[0106] This embodiment 1 provides a process for preparing a positive electrode sheet having a solid electrolyte coating and a semi-solid electrolyte coating, and the specific steps are as follows:

[0107] 1) Preparation of a polymer electrolyte precursor liquid: a first polymer polyvinylidene fluoride (PVDF) and a crosslinker neopentyl glycol diacrylate (NPGDA) are dispersed in a solvent containing 1 mol / L lithium hexafluorophosphate (the solvent formula is: a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 (the mass ratio of the solvent containing 1 mol / L lithium hexafluorophosphate to polyvinylidene fluoride is 90:2); then a first inorganic filler lanthanum zirconate with an average particle size of 300 nm (the mass ratio w1 of lanthanum zirconate and polyvinylidene fluoride is 15:100) is added and mixed, 0.002 mol / L initiator azobisisobutyronitrile (AIBN) is added (the mass ratio of the solvent containing 1 mol / L lithium hexafluorophosphate to azobisisobutyronitrile is 850:2) and stirred uniformly to obtain a polymer electrolyte precursor liquid;

[0108] 2) preparing a colloidal solution: dispersing a second inorganic filler, lithium lanthanum zirconate, having an average particle size of 300 nm in a 1-methyl-2-pyrrolidone (NMP) solvent to obtain a dispersed solution, and then adding a lithium salt, lithium bistrifluoromethylsulfonyl imide (LiTFSI), and a second polymer, polyvinylidene fluoride (PVDF), in a mass ratio of 1:4 (the mass ratio w2 of lithium lanthanum zirconate to PVDF is 75:100) to the dispersed solution and mixing to form a uniform colloidal solution;

[0109] 3) Coating the positive electrode active material coating: lithium cobalt oxide, conductive agent carbon black, and binder polyvinylidene fluoride were mixed in an NMP solvent in a mass ratio of 95:3:2 to prepare a positive electrode active slurry, and the positive electrode active slurry was applied to both sides of the positive electrode current collector aluminum foil to form a positive electrode active material coating. After drying, cold pressing, slitting, and laser drilling, a positive electrode sheet was obtained. D1 is the thickness of the positive electrode sheet after cold pressing. The first concave hole was set in the positive electrode active material coating by laser drilling, and the depth of the first concave hole was 0.4D1;

[0110] 4) Applying a first semi-solid electrolyte coating: applying a polymer electrolyte precursor liquid to the surface of the positive electrode active material coating facing away from the positive electrode current collector by a casting process, and the polymer electrolyte precursor liquid is in situ polymerized in the positive electrode active material coating to form a gel-like first semi-solid electrolyte coating. The thickness D2 of the first semi-solid electrolyte coating is adjusted by adjusting the scraper gap;

[0111] 5) Applying the first solid electrolyte coating: applying the colloidal solution to the surface of the first semi-solid electrolyte coating away from the positive electrode active material coating by a casting process to form a first solid electrolyte coating. The thickness D3 of the first solid electrolyte coating is adjusted by adjusting the scraper gap.

[0112] In Example 1, the thickness of the positive electrode active material coating layer is D1 = 72 μm, the thickness of the first semi-solid electrolyte coating layer is D2 = 0.9 μm, and the thickness of the first solid electrolyte coating layer is D3 = 3.4 μm. The mass percentage of the first inorganic filler to the mass percentage of the first polymer is w1 = 15%, and the mass percentage of the second inorganic filler to the mass percentage of the second polymer is w2 = 75%.

[0113] This embodiment 1 provides a process for preparing a negative electrode sheet having a solid electrolyte coating and a semi-solid electrolyte coating, and the specific steps are as follows:

[0114] 1) Preparation of a polymer electrolyte precursor liquid: a third polymer polyvinylidene fluoride (PVDF) and a crosslinker neopentyl glycol diacrylate (NPGDA) are dispersed in a solvent containing 1 mol / L lithium hexafluorophosphate (the solvent formula is: a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 (the mass ratio of the solvent containing 1 mol / L lithium hexafluorophosphate to polyvinylidene fluoride is 90:2); then a third inorganic filler lanthanum zirconate with an average particle size of 300 nm (the mass ratio w3 of lanthanum zirconate and polyvinylidene fluoride is 15:100) is added and mixed, 0.002 mol / L initiator azobisisobutyronitrile (AIBN) is added (the mass ratio of the solvent containing 1 mol / L lithium hexafluorophosphate to azobisisobutyronitrile is 850:2) and stirred uniformly to obtain a polymer electrolyte precursor liquid;

[0115] 2) preparing a colloidal solution: dispersing a fourth inorganic filler, lithium lanthanum zirconate, having an average particle size of 300 nm in 1-methyl-2-pyrrolidone solvent (NMP) to obtain a dispersed solution, and then adding lithium salt lithium bistrifluoromethylsulfonyl imide (LiTFSI) and a fourth polymer polyvinylidene fluoride (PVDF) in a mass ratio of 1:4 (the mass ratio w4 of lithium lanthanum zirconate and polyvinylidene fluoride is 75:100) to the dispersed solution and mixing to form a uniform colloidal solution;

[0116] 3) Coating the negative electrode active material coating: Graphite, conductive agent acetylene black, binder styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) are mixed in a deionized water solvent in a mass ratio of 90:5:3:2 to prepare a negative electrode active slurry, and the negative electrode active slurry is applied to both sides of the negative electrode current collector copper foil to form a negative electrode active material coating. After drying, cold pressing, slitting, and laser drilling, a negative electrode sheet is obtained. D4 is the thickness of the negative electrode sheet after cold pressing. The second concave hole is set in the positive electrode active material coating by laser drilling, and the depth of the second concave hole is 0.4D4;

[0117] 4) Applying a second semi-solid electrolyte coating: applying a polymer electrolyte precursor liquid to the surface of the negative electrode active material coating facing away from the negative electrode current collector by a tape casting process. The polymer electrolyte precursor liquid is in situ polymerized in the negative electrode active material coating to form a gel-like second semi-solid electrolyte coating. The thickness D5 of the second semi-solid electrolyte coating is adjusted by adjusting the scraper gap.

[0118] 5) Applying the second solid electrolyte coating: applying the colloidal solution to the surface of the second semi-solid electrolyte coating away from the negative electrode active material coating by a casting process to form a second solid electrolyte coating. The thickness D6 of the second solid electrolyte coating is adjusted by adjusting the scraper gap.

[0119] In this first embodiment, the thickness of the negative electrode active material coating layer is D4 = 68 μm, the thickness of the second semi-solid electrolyte coating layer is D5 = 3.3 μm, and the thickness of the first solid electrolyte coating layer is D6 = 0.8 μm. The mass percentage of the third inorganic filler to the first polymer is w3 = 15%, and the mass percentage of the fourth inorganic filler to the second polymer is w4 = 75%.

[0120] After the positive electrode sheet 100 and the negative electrode sheet 200 are stacked, a battery cell is prepared through a winding process, which is then placed into a shell and then encapsulated and injected with electrolyte to produce a finished battery.

[0121] It should be noted that the above-mentioned polymer electrolyte precursor liquid is used to prepare the first solid electrolyte coating of the positive electrode sheet and the second solid electrolyte coating of the negative electrode sheet, and the colloidal solution is used to prepare the first semi-solid electrolyte coating of the positive electrode sheet and the second semi-solid electrolyte coating of the negative electrode sheet.

[0122] In the following Examples 2 to 21, and Comparative Examples 1 to 7, the thickness D1 of the positive electrode active material layer and the thickness D4 of the negative electrode active material layer are controlled by adjusting the rolling pressure during cold pressing. However, in the following Examples 2 to 21, and Comparative Examples 1 to 7, D1 and D4 are the same as those in Example 1, that is, D1 = 72 μm, D4 = 68 μm.

[0123] The electrolyte coating thickness D2, D3, D5 and D6 are controlled by adjusting the scraper gap; by keeping the mass of the first polymer, the second polymer, the third polymer and the fourth polymer unchanged (that is, the mass of the polymers in Examples 1 to 10 and Comparative Examples 1 to 7 are the same), only changing the mass of the first inorganic filler, the second inorganic filler, the third inorganic filler and the fourth inorganic filler, the mass ratios W1, W2, W3 and W4 of the polymer and the inorganic filler are adjusted.

[0124] Example 2

[0125] The only difference between Example 2 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, D5 = 4.3 μm, and D6 = 1.1 μm.

[0126] Example 3

[0127] The only difference between Example 3 and Example 1 is that D2 = 1.4 μm, D3 = 5.8 μm, D5 = 5.4 μm, and D6 = 1.4 μm.

[0128] Example 4

[0129] The only difference between Example 4 and Example 1 is that D2 = 1.0 μm, D3 = 4.8 μm, D5 = 4.5 μm, and D6 = 0.9 μm.

[0130] Example 5

[0131] The only difference between Example 5 and Example 1 is that D2 = 1.4 μm, D3 = 4.4 μm, D5 = 4.1 μm, and D6 = 1.3 μm.

[0132] Example 6

[0133] The only difference between Example 6 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w1 = 10%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 10%.

[0134] Example 7

[0135] The only difference between Example 7 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w1 = 20%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 20%.

[0136] Example 8

[0137] The only difference between Example 8 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w2 = 70%; D5 = 4.3 μm, D6 = 1.1 μm, w4 = 70%.

[0138] Example 9

[0139] The only difference between Example 9 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w2 = 80%; D5 = 4.3 μm, D6 = 1.1 μm, w4 = 80%.

[0140] Example 10

[0141] The only difference between Example 10 and Example 1 is that D2 = 1.7 μm, D3 = 6.9 μm, w1 = 10%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 10%.

[0142] Example 11

[0143] The only difference between Example 11 and Example 1 is that D2 = 1.7 μm, D3 = 6.9 μm, w1 = 20%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 20%.

[0144] Example 12

[0145] The only difference between Example 12 and Example 1 is that D2 = 1.7 μm, D3 = 6.9 μm, w2 = 70%; D5 = 4.3 μm, D6 = 1.1 μm, w4 = 70%.

[0146] Example 13

[0147] The only difference between Example 13 and Example 1 is that D2 = 1.7 μm, D3 = 6.9 μm, w2 = 80%; D5 = 4.3 μm, D6 = 1.1 μm, w4 = 80%.

[0148] Example 14

[0149] The only difference between Example 14 and Example 1 is that D2 = 1.7 μm, D3 = 6.9 μm; D5 = 6.6 μm, D6 = 1.6 μm.

[0150] Example 15

[0151] The only difference between Example 15 and Example 1 is that in the step of preparing the polymer electrolyte precursor liquid for the positive electrode sheet and the negative electrode sheet, the polymer polyvinylidene fluoride is replaced by polyethylene oxide, and the inorganic filler lithium lanthanum zirconate is replaced by lithium lanthanum titanate; in the step of preparing the colloidal solution for the positive electrode sheet and the negative electrode sheet, the polymer polyvinylidene fluoride is replaced by polyethylene oxide, and the inorganic filler lithium lanthanum zirconate is replaced by lithium lanthanum titanate.

[0152] Example 16

[0153] The only difference between Example 16 and Example 1 is that D2 = 0.6 μm, D3 = 2.3 μm, D5 = 2.2 μm, and D6 = 0.5 μm.

[0154] Example 17

[0155] The only difference between Example 17 and Example 1 is that D2 = 2.0 μm, D3 = 8.1 μm, D5 = 7.6 μm, and D6 = 1.9 μm.

[0156] Example 18

[0157] The only difference between Example 18 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w1 = 5%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 5%.

[0158] Example 19

[0159] The only difference between Example 19 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w1 = 25%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 25%.

[0160] Example 20

[0161] The only difference between Example 20 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w2 = 60%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 60%.

[0162] Example 21

[0163] The only difference between Example 21 and Example 1 is that D2 = 1.2 μm, D3 = 4.6 μm, w2 = 90%; D5 = 4.3 μm, D6 = 1.1 μm, w3 = 90%.

[0164] Comparative Example 1

[0165] The only difference between Comparative Example 1 and Example 1 is that D2 = 0.8 μm, D3 = 5.0 μm, D5 = 4.6 μm, and D6 = 0.8 μm.

[0166] Comparative Example 2

[0167] The only difference between Comparative Example 2 and Example 1 is that D2 = 1.9 μm, D3 = 3.9 μm, D5 = 3.6 μm, and D6 = 1.8 μm.

[0168] Comparative Example 3

[0169] The only difference between Comparative Example 3 and Example 1 is that the positive electrode plate 100 provided in Comparative Example 3 is not provided with the first semi-solid electrolyte coating 103 and the first solid electrolyte coating 104, that is, step 1), step 3) and step 4) are omitted in the preparation process of the positive electrode plate 100, that is, D2 = 0 μm, D3 = 0 μm, w1 = 0; w2 = 0; D5 = 4.3 μm, D6 = 1.1 μm.

[0170] Comparative Example 4

[0171] The only difference between Comparative Example 4 and Example 1 is that the negative electrode plate 200 provided in Comparative Example 4 is not provided with the second semi-solid electrolyte coating 203 and the second solid electrolyte coating 204, that is, step 1), step 3) and step 4) are omitted in the preparation process of the negative electrode plate 200, that is, D5=0, D6=0, w3=0, w4=0; D2=1.2μm, D3=4.6μm.

[0172] Comparative Example 5

[0173] The only difference between Comparative Example 5 and Example 1 is that the positive electrode plate 100 provided in Comparative Example 5 is not provided with a first semi-solid electrolyte coating 103, that is, the process of obtaining the polymer electrolyte precursor liquid in step 1) and step 4) are omitted in the preparation process of the positive electrode plate 100, that is, D2 = 0 μm, W1 = 0 μm; D3 = 5.8 μm; the negative electrode plate 200 provided in Comparative Example 5 is not provided with a second semi-solid electrolyte coating 203, that is, the process of obtaining the polymer electrolyte precursor liquid in step 1) and step 4) are omitted in the preparation process of the negative electrode plate 200, that is, D5 = 0 μm, W3 = 0 μm; D6 = 5.4 μm.

[0174] Comparative Example 6

[0175] The only difference between Comparative Example 6 and Example 1 is that the positive electrode plate 100 provided in Comparative Example 6 is not provided with the first solid electrolyte coating 104, that is, the process of obtaining the colloidal solution in step 2) and step 5) are omitted in the preparation process of the positive electrode plate 100, that is, D3 = 0 μm, W1 = 0 μm; D2 = 5.8 μm; the negative electrode plate 200 provided in Comparative Example 6 is not provided with the second semi-solid electrolyte coating 203, that is, the process of obtaining the third colloidal solution in step 2) and step 5) are omitted in the preparation process of the negative electrode plate 200, that is, D6 = 0 μm, W3 = 0 μm; D5 = 5.4 μm.

[0176] Comparative Example 7

[0177] The only difference between Comparative Example 7 and Example 1 is that D2 = 2.9 μm, D3 = 2.9 μm, D5 = 2.7 μm, and D6 = 2.7 μm.

[0178] The specific data of the above twenty-one embodiments and seven comparative examples are summarized to obtain

[0179] Table 1 is as follows:

[0180]

[0181] Table 1

[0182] It can be seen from Table 1 that the positive electrode sheets 100 and the negative electrode sheets 200 of Examples 1 to 17 and Comparative Examples 1, 2 and 7 all meet the conditions of 10%≤w1≤20%; 70%≤w2≤80%; 10%≤w3≤20%; and 70%≤w4≤80%.

[0183] At least one of the positive electrode sheets 100 and the negative electrode sheets 200 in Examples 18 to 21, and Comparative Examples 3 to 6 does not satisfy the conditions of 10% ≤ w1 ≤ 20%; 70% ≤ w2 ≤ 80%; 10% ≤ w3 ≤ 20%; and 70% ≤ w4 ≤ 80%.

[0184] The specific data of the above 21 embodiments and 7 comparative examples and the specific data of Table 1 are summarized to obtain D1: (D2+D3), D2+D3, D2 / D3, D4 / (D5+D6), D5+D6, and D5 / D6 of Examples 1 to 21 and Comparative Examples 1 to 7 as shown in Table 2 below:

[0185]

[0186]

[0187] Table 2

[0188] It can be seen from Table 2 that the positive electrode sheets and negative electrode sheets of Examples 1 to 21 all meet the conditions of 0.2<D2 / D3<0.33; 3<D5 / D6≤5; D2<D5, D3>D6.

[0189] The positive electrode sheets 100 and negative electrode sheets 200 of Examples 1 to 15, and Examples 18 to 21 all satisfy the conditions of 8<D1 / (D2+D3)<17; 8<D4 / (D5+D6)<17; 4.3≤D2+D3≤8.6; 4.1≤D5+D6≤8.2.

[0190] Examples 1 to 21, and Comparative Examples 1, 2, and 7 all satisfy the condition of 0.92≤(D2*D5) / (D3*D6)≤1.08.

[0191] Example 16 and Example 17 do not satisfy the conditions of 8<D1 / (D2+D3)<17; 8<D4 / (D5+D6)<17.

[0192] Example 16, Example 17 and Comparative Example 3 do not satisfy the condition of 4.3≤D2+D3≤8.6.

[0193] Comparative Examples 1 to 3, and Comparative Examples 5 to 7 do not satisfy the condition of 0.2<D2 / D3<0.33.

[0194] Example 16, Example 17, and Comparative Example 4 do not satisfy the condition of 4.1≤D5+D6≤8.2.

[0195] Comparative Examples 3 to 2, and Comparative Examples 4 to 7 do not satisfy the condition of 3<D5 / D6≤5.

[0196] Although Examples 18 to 21 all satisfy 8<D1 / (D2+D3)<17; 8<D4 / (D5+D6)<17; 4.3≤D2+D3≤8.6; 0.2<D2 / D3<0.33; 4.1≤D5+D6≤8.2, 3<D5 / D6≤5 in Table 2, but in Table 1, at least one of the positive electrode sheet 100 and the negative electrode sheet 200 does not satisfy the conditions of 10%≤w1≤20%; 70%≤w2≤80%; 10%≤w3≤20%; 70%≤w4≤80%.

[0197] (1) The battery cycle performance test method is as follows: in an environment of 25°C, charge and discharge according to the following method: charge; the battery cell is charged to 4.10V at a rate of 2.5C, then charged to 4.20V at a rate of 2.5C, charged to 4.30V at a rate of 1.5C, charged to 4.53V at a rate of 1.0C, and then discharged to 3.0V at a rate of 0.7C, and cycled 600 times.

[0198] Cycle capacity retention rate = (discharge capacity at the 600th cycle / discharge capacity at the first cycle) × 100%;

[0199] Cyclic expansion retention rate = (thickness at the 600th cycle - initial half-electricity thickness) / initial half-electricity thickness * 100%;

[0200] Initial half-charge thickness: Charge at a constant current of 0.5C to 3.9V and a constant voltage of 0.02C. All cell thicknesses are tested using 600PPG.

[0201] (2) The test method for the battery's liquid retention coefficient is as follows: when preparing each battery product, weigh the cell mass M1 before filling, weigh the mass M2 after filling, and after leaving it for 24 hours, drain the excess electrolyte and weigh the cell mass M3. The filling volume = M2-M1, the loss volume = M2-M3, and the liquid retention coefficient = liquid retention volume / discharge capacity, where liquid retention volume = filling volume - loss volume; the discharge capacity is determined by charge and discharge testing. Use professional battery charging and discharging equipment to perform a complete charge and discharge cycle on the battery. During the charging process, record the charging current and charging time, and calculate the charging capacity according to the formula "charging capacity = charging current * charging time"; during the discharging process, also record the discharge current and discharge time, and calculate the discharge capacity according to the formula "discharge capacity = discharge current * discharge time".

[0202] (3) The test method for the lithium deposition level of the battery corners is as follows: take parallel samples of the battery cells obtained in each embodiment and comparative example and perform step (1) for a cycle, then disassemble the battery cells, remove the packaging film from the battery cells, unfold them along the winding direction, separate the diaphragm and the electrode, and observe the interface of the negative electrode. If there is no lithium deposition at the corners, it is marked as level 0; if there is point-like lithium deposition at the corners, it is marked as level 1; if there is linear lithium deposition at the corners, but it is not continuous, it is marked as level 2; if there is linear lithium deposition at the corners and it is continuous, it is marked as level 3; each group of parallel samples is tested with 5 samples, and the highest level among the samples is counted.

[0203] (4) The hot box safety test method for the battery is as follows: place the battery cells in a hot box (5 pcs / furnace), and increase the oven temperature to 130℃ / 132℃ / 134℃ / 136℃ at a rate of (5±2)℃ / min and keep it for 60 minutes before stopping. If the battery does not catch fire or explode, it is considered to have passed the furnace temperature test.

[0204] (5) The test method for the self-discharge K value of the battery is: in an environment of 25+ / -3℃, test the battery voltage V1 at t1, and test the voltage V2 of the same battery at t2. Self-discharge K = (V1-V2) / (t2-t1).

[0205] The test samples were set as five groups of parallel samples, and the final test results were calculated as the average value of the five groups of parallel samples.

[0206] The batteries provided in Examples 1 to 21 and Comparative Examples 1 to 7 were tested using the above-mentioned cycle performance test method, rate discharge test method, liquid retention coefficient test method, corner lithium deposition level test method, hot box test method, and self-discharge K value test method. The specific test results are shown in Table 3 below:

[0207]

[0208]

[0209] Table 3

[0210] It should be noted that in the test structure of the hot box test, 136 (5 / 5 pass) means that there are five groups of test samples in the 136° furnace temperature test and all five groups of test samples can pass the 136° furnace temperature test; 136 (1 / 5 pass) means that there are five groups of test samples in the 136° furnace temperature test and only one group of the five groups of test samples passes the 136° furnace temperature test; 134 (1 / 5 pass) means that there are five groups of test samples in the 134° furnace temperature test and only one group of the five groups of test samples passes the 134° furnace temperature test; 132 (4 / 5 pass) means that there are five groups of test samples at 132° and only four groups of test samples pass the 132° furnace temperature test, and so on.

[0211] It can be seen from Tables 1 to 3 that when the positive electrode sheet 100 and the negative electrode sheet 200 of the battery both meet the conditions of 10%≤w1≤20%, 70%≤w2≤80%, 8<D1 / (D2+D3)<17, 8<D4 / (D5+D6)<17, 4.3≤D2+D3≤8.6, 4.1≤D5+D6≤8.2, 0.2<D2 / D3<0.33, 3<D5 / D6≤5, D2<D5 and D3>D6, the battery's cycle capacity retention rate, liquid retention coefficient, lithium plating level, K value and hot box test are significantly better, that is, the batteries provided in Examples 1 to 15 have better electrode liquid retention ability, better battery cycle performance, less lithium plating phenomenon, lower battery self-discharge rate, and better performance in the hot box safety performance test.

[0212] By comparing Examples 1 to 15 and Examples 16 to 17 in Tables 1 to 3, the only difference between Examples 1 to 15 and Examples 16 to 17 is that Examples 16 to 17 do not meet the conditions of 8 < D1 / (D2+D3) < 17; 4.3 ≤ D2+D3 ≤ 8.6; 8 < D4 / (D5+D6) < 17; 4.1 ≤ D5+D6 ≤ 8.2. The cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation grade and K value of Examples 1 to 15 are significantly better than those of Examples 16 to 17. Therefore, the thickness of the functional coatings (i.e., active material coating, semi-solid electrolyte coating and solid electrolyte coating) of the positive electrode plate 100 and the negative electrode plate 200 can well meet the dynamic performance within an appropriate range. The semi-solid electrolyte coating is embedded in the electrode plate perforation area to form a three-dimensional transmission network with the electrode plate, which is beneficial to ion diffusion, while improving the electrode plate's liquid retention capacity, effectively improving the battery's cycle performance and lithium precipitation phenomenon; the solid electrolyte coating has excellent thermal stability, mechanical strength and ionic conductivity, which can inhibit dendrite growth, provide mechanical protection and isolation for the surface, and improve the battery's performance in hot box safety performance tests; the asymmetric distribution of the positive and negative electrode coatings, and the difference in the content of inorganic ceramic electrolytes in the semi-solid electrolyte coating and the solid electrolyte coating, bring beneficial improvements to the battery's interface transmission, thermal stability and long cycle performance.

[0213] Comparing Example 6 and Example 18 in Tables 1 to 3, the only difference between Example 6 and Example 18 is that in Example 6, w1=w3=10%, which satisfies the conditions of 10%≤w1≤20% and 10%≤w3≤20%; in Example 18, w1=w3=5%, which does not satisfy the conditions of 10%≤w1≤20% and 10%≤w3≤20%. The cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation grade and K value of Example 6 are significantly better than those of Example 18.

[0214] Comparing Example 6 and Example 19 in Tables 1 to 3, the only difference between Example 6 and Example 19 is that in Example 6, w1=w3=10%, which satisfies the conditions of 10%≤w1≤20% and 10%≤w3≤20%; in Example 19, w1=w3=25%, which does not satisfy the conditions of 10%≤w1≤20% and 10%≤w3≤20%. The cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation grade and K value of Example 6 are significantly better than those of Example 19.

[0215] Comparing Example 6 and Example 20 in Tables 1 to 3, the only difference between Example 6 and Example 20 is that in Example 6, w2=w4=75%, which satisfies the conditions of 70%≤w2≤80% and 70%≤w4≤80%; in Example 20, w2=w4=60%, which does not satisfy the conditions of 70%≤w2≤80% and 70%≤w4≤80%. The cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation grade and K value of Example 6 are significantly better than those of Example 20.

[0216] Comparing Example 6 and Example 21 in Tables 1 to 3, the only difference between Example 6 and Example 21 is that in Example 6, w2=w4=75%, which satisfies the conditions of 70%≤w2≤80% and 70%≤w4≤80%; in Example 21, w2=w4=90%, which does not satisfy the conditions of 70%≤w2≤80% and 70%≤w4≤80%. The cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation grade and K value of Example 6 are significantly better than those of Example 21.

[0217] Comparing Examples 1 to 15 in Tables 1 to 3 with Comparative Examples 1 to 2, in Comparative Example 1, D2 / D3=0.16, D5 / D6=5.75, which do not meet the conditions of 0.2<D2 / D3<0.33 and 3<D5 / D6≤5. In Comparative Example 2, D2 / D3=0.49, D5 / D6=2, which do not meet the conditions of 0.2<D2 / D3<0.33 and 3<D5 / D6≤5. The cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation grade and K value of Examples 1 to 15 are significantly better than those of Comparative Examples 1 to 2.

[0218] Comparing Example 2 with Comparative Example 3 in Tables 1 to 3, in Example 2, the positive electrode plate is provided with a first semi-solid electrolyte coating and a first solid electrolyte coating, and the negative electrode plate is provided with a second semi-solid electrolyte coating and a second solid electrolyte coating, D4=4.3, D6=1.1, D5+D6=5.4, w1=15%, w2=75%; in Comparative Example 3, the positive electrode plate is provided with neither the first semi-solid electrolyte coating nor the first solid electrolyte coating; the negative electrode plate is provided with a second semi-solid electrolyte coating. coating and a second solid electrolyte coating; D4=4.3, D6=1.1, D5+D6=5.4, w1=15%, w2=75%; therefore, the only difference between Example 2 and Comparative Example 3 is that the positive electrode plate of Example 2 is provided with a positive electrode side composite functional layer (a first semi-solid electrolyte coating and a first solid electrolyte coating), and the positive electrode plate of Comparative Example 3 is not provided with a positive electrode side composite functional layer, and the cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation level and K value of Example 2 are significantly better than those of Comparative Example 3.

[0219] Comparing Example 2 with Comparative Example 4 in Tables 1 to 3, in Example 2, the positive electrode plate is provided with a first semi-solid electrolyte coating and a first solid electrolyte coating, D2 = 1.2, D3 = 4.6, D2 + D3 = 5.8, w1 = 15%, w2 = 75%; the negative electrode plate is provided with a second semi-solid electrolyte coating and a second solid electrolyte coating; in Comparative Example 4, the positive electrode plate is provided with a first semi-solid electrolyte coating and a first solid electrolyte coating; D2 = 1.2, D3 = 4.6, D2 + D3 = 5.8, w1=15%, w2=75%; the negative electrode plate is neither provided with a second semi-solid electrolyte coating nor a second solid electrolyte coating; therefore, the only difference between Example 2 and Comparative Example 4 is that the positive electrode plate of Example 2 is provided with a positive electrode side composite functional layer (a first semi-solid electrolyte coating and a first solid electrolyte coating), and the positive electrode plate of Comparative Example 4 is not provided with a positive electrode side composite functional layer, and the cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient lithium precipitation level and K value of Example 2 are significantly better than those of Comparative Example 4.

[0220] Comparing Example 2 with Comparative Example 5 in Tables 1 to 3, in Example 2, the positive electrode plate is provided with a first semi-solid electrolyte coating and a first solid electrolyte coating, D2 = 1.2, D3 = 4.6, D2 + D3 = 5.8, w1 = 15%, w2 = 75%; the negative electrode plate is provided with a second semi-solid electrolyte coating and a second solid electrolyte coating, D4 = 4.3, D6 = 1.1, D5 + D6 = 5.4, w1 = 15%, w2 = 75%; in Comparative Example 5, the positive electrode plate is provided with a first solid electrolyte coating but not a first semi-solid electrolyte coating, D2 = 0, D3 = 5.8, D 2+D3=5.8, w1=15%, w2=75%; the negative electrode plate is provided with a second solid electrolyte coating, but not with a second semi-solid electrolyte coating; D4=0, D6=5.4, D5+D6=5.4, w1=15%, w2=75%; therefore, the only difference between Example 2 and Comparative Example 5 is that the positive electrode plate and the negative electrode plate of Example 2 are both provided with a solid electrolyte coating and a semi-solid electrolyte coating, and the positive electrode plate and the negative electrode plate of Comparative Example 5 are only provided with a solid electrolyte coating, and the cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient lithium precipitation grade and K value of Example 2 are significantly better than those of Comparative Example 5.

[0221] Comparing Example 2 with Comparative Example 6 in Tables 1 to 3, in Comparative Example 6, the positive electrode plate is provided with a first semi-solid electrolyte coating, but is not provided with a first solid electrolyte coating, D2=5.8, D3=0, D2+D3=5.8, w1=15%, w2=75%; the negative electrode plate is provided with a second semi-solid electrolyte coating, but is not provided with a second solid electrolyte coating; D4=5.4, D6=0, D5+D6=5.4, w1=15%, w2=75%; therefore, the only difference between Example 2 and Comparative Example 6 is that the positive electrode plate and the negative electrode plate of Example 2 are both provided with a solid electrolyte coating and a semi-solid electrolyte coating, and the positive electrode plate and the negative electrode plate of Comparative Example 6 are only provided with a semi-solid electrolyte coating, and the cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient, lithium precipitation grade and K value of Example 2 are significantly better than those of Comparative Example 6.

[0222] Comparing Example 2 with Comparative Example 7 in Tables 1 to 3, in Example 2, D2 / D3=0.26, the thickness of the first semi-solid electrolyte coating of the positive electrode plate is less than the thickness of the first solid electrolyte coating, and the first semi-solid electrolyte coating and the first solid electrolyte coating of the positive electrode plate are asymmetric; D5 / D6=3.91, the thickness of the second semi-solid electrolyte coating of the negative electrode plate is greater than the thickness of the second solid electrolyte coating, and the second semi-solid electrolyte coating and the second solid electrolyte coating of the negative electrode plate are asymmetric; in Comparative Example 7, the positive electrode plate is provided with a first semi-solid electrolyte coating and a first solid electrolyte coating, D2 / D3=1 , D2=2.9, D3=2.9, D2+D3=5.8, w1=15%, w2=75%, the first semi-solid electrolyte coating and the first solid electrolyte coating of the positive electrode sheet are symmetrical; the negative electrode sheet is provided with a second semi-solid electrolyte coating and a second solid electrolyte coating; D5 / D6=1, D4=2.7, D6=2.7, D5+D6=5.4, w1=15%, w2=75%, the second semi-solid electrolyte coating and the second solid electrolyte coating of the negative electrode sheet are symmetrical; the cycle capacity retention rate, cycle expansion retention rate, liquid retention coefficient lithium precipitation grade and K value of Example 2 are significantly better than those of Comparative Example 7.

[0223] By comparing Example 1 and Example 3 to Example 21 in Tables 1 to 3 with Comparative Example 7, Example 1 and Example 3 to Example 21 all satisfy 0.2<D2 / D3<0.33; 3<D5 / D6≤5; D2<D5, D3>D6. The cycle capacity retention rates of Examples 1 to Example 21 are all better than those of Comparative Example 7. It can be found that the cycle capacity retention rate characterizes the ability of the battery to maintain its initial capacity after multiple charge and discharge cycles. Therefore, the battery performance of Examples 1 to Example 21 is better than that of Comparative Example 7.

[0224] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A battery cell, characterized in that: include: A positive electrode plate (100) comprises a positive electrode current collector (101), a positive electrode active material coating (102), a first semi-solid electrolyte coating (103) and a first solid electrolyte coating (104), wherein the positive electrode active material coating (102) is provided on one or both surfaces of the positive electrode current collector (101), the first semi-solid electrolyte coating (103) is provided on a surface of the positive electrode active material coating (102) away from the positive electrode current collector (101), and the first solid electrolyte coating (104) is provided on a surface of the first semi-solid electrolyte coating (103) away from the positive electrode active material coating (102); A negative electrode plate (200) comprises a negative electrode current collector (201), a negative electrode active material coating (202), a second semi-solid electrolyte coating (203) and a second solid electrolyte coating (204), wherein the negative electrode active material coating (202) is provided on one or both surfaces of the negative electrode current collector (201), the second semi-solid electrolyte coating (203) is provided on a surface of the negative electrode active material coating (202) away from the negative electrode current collector (201), and the second solid electrolyte coating (204) is provided on a surface of the second semi-solid electrolyte coating (203) away from the negative electrode active material coating (202); The thickness of the first semi-solid electrolyte coating (103) is D2 μm, the thickness of the first solid electrolyte coating (104) is D3 μm, the thickness of the second semi-solid electrolyte coating (203) is D5 μm, and the thickness of the second solid electrolyte coating (204) is D6 μm; and the following conditions are satisfied: 0.2<D2 / D3<0.33; 3<D5 / D6≤5; D2<D5, D3>D6.

2. The battery cell according to claim 1, characterized in that The thickness of the positive electrode active material coating (102) is D1 μm, and the thickness of the negative electrode active material coating (202) is D4 μm, satisfying the following conditions: 8<D1 / (D2+D3)<17; 4.3≤D2+D3≤8.6; 8<D4 / (D5+D6)<17; 4.1≤D5+D6≤8.

2.

3. The battery cell according to claim 1 or claim 2, characterized in that: 0.92≤(D2*D5) / (D3*D6)≤1.

08.

4. The battery cell according to claim 1, characterized in that The first semi-solid electrolyte coating (103) includes a first polymer and a first inorganic filler; The first solid electrolyte coating (104) includes a second polymer and a second inorganic filler; Wherein, in the first semi-solid electrolyte coating (103), the mass ratio of the first inorganic filler to the first polymer is w1; in the first solid electrolyte coating (104), the mass ratio of the second inorganic filler to the second polymer is w2; and the following conditions are satisfied: 10%≤w1≤20%; 70%≤w2≤80%.

5. The battery cell according to claim 4, characterized in that: The second semi-solid electrolyte coating (203) includes a third polymer and a third inorganic filler; The second solid electrolyte coating (204) includes a fourth polymer and a fourth inorganic filler; Wherein, in the second semi-solid electrolyte coating (203), the mass ratio of the third inorganic filler to the third polymer is w3; in the second solid electrolyte coating (204), the mass ratio of the fourth inorganic filler to the fourth polymer is w4; satisfying: 10%≤w3≤20%; 70%≤w4≤80%.

6. The battery cell according to claim 5, characterized in that The first polymer and the third polymer are each independently selected from at least one of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyvinyl alcohol, and polymethyl methacrylate; and / or, The second polymer and the fourth polymer are each independently selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide, and polyacrylate; and / or, The first inorganic filler, the second inorganic filler, the third inorganic filler and the fourth inorganic filler are each independently selected from at least one of a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a LISICON-type solid electrolyte and a NASICON-type solid electrolyte.

7. The battery cell according to claim 5, characterized in that w1=w3; w2=w4.

8. The battery cell according to claim 1, characterized in that In the adjacent positive electrode plate (100) and the negative electrode plate (200), a side of the first solid electrolyte coating (104) facing away from the first semi-solid electrolyte coating (103) is adhered to a side of the second solid electrolyte coating (204) facing away from the second semi-solid electrolyte coating (203).

9. The battery cell according to claim 1, characterized in that: The positive electrode active material coating (102) is provided with a plurality of first concave holes (1021) on a side facing away from the positive electrode current collector (101), and at least a portion of the first semi-solid electrolyte coating (103) is located in the first concave holes (1021); and / or, the negative electrode active material coating (202) is provided with a plurality of second concave holes (2021) on a side facing away from the negative electrode current collector (201), and at least a portion of the second semi-solid electrolyte coating (203) is located in the second concave holes (2021).

10. A battery, characterized in that: Comprising the battery cell according to any one of claims 1 to 9.

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