Gel electrolyte battery, power utilization device and preparation method

Abstract

The invention provides a gel electrolyte battery which comprises a gel electrolyte, the gel electrolyte comprises a first gel electrolyte (410) and a second gel electrolyte (420), the first gel electrolyte is located in at least one part of the surface of at least one side of at least one electrode plate (100), and the second gel electrolyte is located in at least one part of the surface of at least one side of at least one electrode plate (100). The second gel electrolyte is positioned in the direction, far away from the electrode plate, of the first gel electrolyte; and the electrode pole piece is a positive pole piece or a negative pole piece.

Description

Gel electrolyte battery, electrical device and preparation method Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to gel electrolyte batteries, electrical devices, and preparation methods. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] With the popularization and development of various electronic products such as smartphones, tablets, smart wearables, power tools and electric vehicles, the application of secondary batteries has involved all aspects of people's daily lives. Therefore, the safety issue of secondary batteries has become increasingly important and it is necessary to improve the safety of secondary batteries while maintaining good battery performance such as capacity.

[0004] Summary of the Invention

[0005] In view of the above problems, this application provides a gel electrolyte battery, an electrical device, and a preparation method. The gel electrolyte contained in the gel electrolyte battery has a special cross-linking distribution, which can give the battery higher rigidity while maintaining good battery capacity, thereby improving battery safety.

[0006] In a first aspect, the present application provides a gel electrolyte battery, comprising an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode sheet and a negative electrode sheet; the electrolyte comprises a gel electrolyte, and the gel electrolyte comprises a first gel electrolyte and a second gel electrolyte; the first gel electrolyte is located in at least a portion of at least one side surface of at least one electrode sheet, and the second gel electrolyte is located on a side of the first gel electrolyte away from the electrode sheet; the electrode sheet is the positive electrode sheet or the negative electrode sheet;

[0007] The cross-linking degree of the gel portion of the second gel electrolyte is higher than the cross-linking degree of the gel portion of the first gel electrolyte.

[0008] In the aforementioned gel electrolyte battery, the gel electrolyte in the battery cell can improve the rigidity of the secondary battery. Furthermore, a combination distribution of a first gel electrolyte with a low degree of cross-linking (located on at least one side of the electrode plate) and a second gel electrolyte with a high degree of cross-linking and high rigidity (separated from the surface of the electrode plate by the first gel electrolyte) is formed in sequence on the surface of the electrode plate. On the one hand, the surface of the electrode plate with a low degree of cross-linking can absorb and swell more liquid electrolyte, thereby having better infiltration in the pores and surface of the electrode plate, which is more conducive to the performance of electrical properties such as capacity. On the other hand, the high degree of cross-linking design away from the electrode surface can give the battery higher rigidity, further enhance the battery's ability to resist deformation during use, thereby significantly improving the safety performance of the battery cell.

[0009] In a first aspect, the present application also provides another gel electrolyte battery, which includes an electrode assembly and an electrolyte; the electrode assembly includes a positive electrode sheet and a negative electrode sheet; the electrolyte includes a gel electrolyte, and the gel electrolyte includes a first gel electrolyte and a second gel electrolyte;

[0010] The first gel electrolyte is located in at least a portion of a first region and a second region: wherein the first region is the surface region of the negative electrode sheet, and the second region is the surface region of the positive electrode sheet;

[0011] The second gel electrolyte is located in at least a portion of the relative space between the positive electrode sheet and the negative electrode sheet;

[0012] The cross-linking degree of the gel portion of the second gel electrolyte is higher than the cross-linking degree of the gel portion of the first gel electrolyte.

[0013] In the aforementioned gel electrolyte battery, the gel electrolyte in the battery cell can improve the rigidity of the secondary battery. Furthermore, a first gel electrolyte with a low degree of cross-linking is arranged on the surface of the electrode plate, and a second gel electrolyte (high rigidity layer) with a high degree of cross-linking is arranged in at least a part of the relative space between the positive and negative plates. The gel electrolyte is controlled to have a coordinated distribution of low cross-linking on the surface of the electrode plate and high cross-linking in the relative space of the electrode plate. On the one hand, the surface of the electrode plate with a low degree of cross-linking can absorb and swell more liquid electrolyte, thereby having better infiltration in the pores and surface of the electrode plate, which is more conducive to the performance of electrical properties such as capacity. On the other hand, the design of high degree of cross-linking in the relative space of the electrode plate can give the battery higher rigidity, further enhance the battery's ability to resist deformation during use, thereby significantly improving the safety performance of the battery cell.

[0014] In some embodiments, the mass ratio m of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2It is (0.2~3):1, can be optionally (0.5~1):1, further can be optionally (0.79~1):1, and further can be optionally 1:1.

[0015] In some embodiments, the volume ratio v of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2 It is (0.2~3):1, can be optionally (0.5~1):1, further can be optionally (0.79~1):1, and further can be optionally 1:1.

[0016] In some embodiments, the crosslinking ratio CX of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2 It is 1:(1~5), can be optionally 1:(1.1~2.0), further can be optionally 1:(1.5~2.0), and further can be optionally 1:(1.8~2.0).

[0017] In some embodiments, the swelling ratio Q of the gel portion of the first gel electrolyte relative to the swelling ratio Q of the gel portion of the second gel electrolyte is 1 / 2 It is (1-4):1, can be optionally (1.3-2.5):1, can be further optionally (1.65-2.0):1, and can be further optionally (1.8-2.0):1.

[0018] In some embodiments, the thermal decomposition temperature ratio Td of the gel portion of the first gel electrolyte relative to the thermal decomposition temperature ratio Td of the gel portion of the second gel electrolyte is 1 / 2 It is 1:(1~4), can be optionally 1:(1.1~2.0), further can be optionally 1:(1.45~2.0), and further can be optionally 1:(1.6~1.8).

[0019] m 1 / 2 and v 1 / 2 The lower the m, the higher the content of the second gel electrolyte, which is more beneficial to improving the battery stiffness. However, if m 1 / 2 and v 1 / 2 If one or both of the above are too low, the content of the second gel electrolyte will be too high, which may affect the filling space of the active material inside the battery and may reduce the energy density, or may cause the battery core to be too full and the internal stress to increase, which may lead to performance deterioration. On the other hand, if the content ratio of the first gel electrolyte is too low, it may lead to insufficient coverage of the first gel electrolyte with low cross-linking degree on the electrode surface, which may lead to poor electrode wetting effect and deterioration of electrical performance such as capacity utilization. 1 / 2 The lower, the Q 1 / 2 The higher or Td 1 / 2The lower the mass ratio, the denser the network structure of the second gel electrolyte is, which is more conducive to providing a higher modulus, thereby being more beneficial to improving the rigidity of the battery. However, it may affect the amount of electrolyte retained between the electrodes, which may deteriorate the battery performance after long-term cycling. 1 / 2 , volume ratio v 1 / 2 , cross-linking degree ratio CX 1 / 2 , swelling ratio Q 1 / 2 and thermal decomposition temperature ratio Td 1 / 2 By adjusting one or more parameters, the ratio of the first gel electrolyte to the second gel electrolyte can be controlled within a more appropriate range, and the synergistic combination between the low cross-linking on the surface of the electrode plate and the high cross-linking in the relative space of the electrode plate can be better coordinated, thereby better optimizing the comprehensive performance of the gel electrolyte battery in terms of capacity, battery stiffness and safety.

[0020] In some embodiments, the first gel electrolyte and the second gel electrolyte both comprise an electrolyte salt;

[0021] The ratio f1 of the mass fraction of the electrolyte salt in the first gel electrolyte to the mass fraction f2 of the electrolyte salt in the second gel electrolyte is 1 / 2 It is 1.5:1 to 1:1.5, and can be optionally 1:(0.7~1.5), further optionally 1:(0.8~1), and further optionally 1:(0.8~0.95).

[0022] In some embodiments, the gel electrolyte battery satisfies one or more of the following features:

[0023] The mass proportion f1 of the electrolyte salt in the first gel electrolyte is 0.7 to 1.2 mol / L, and can be optionally 0.8 to 1.2 mol / L;

[0024] The mass proportion f2 of the electrolyte salt in the second gel electrolyte is 0.7 to 1.2 mol / L, and can be optionally 0.8 to 1.2 mol / L.

[0025] The ratio f1 of the mass fraction of the electrolyte salt in the first gel electrolyte to the mass fraction f2 of the electrolyte salt in the second gel electrolyte is 1 / 2The higher the concentration, the higher the electrolyte salt concentration on the electrode plate surface, which is beneficial for more solvent to participate in solvation coordination, improve solvent stability, reduce side reaction consumption, and improve cycle performance. However, if the concentration difference between the first gel electrolyte and the second gel electrolyte is too large, it may cause a mismatch in the ion diffusion rate between the first gel electrolyte and the second gel electrolyte, which may affect the capacity and rate performance. Furthermore, by controlling the concentration of the electrolyte salt in the first gel electrolyte and / or the second gel electrolyte within a certain range, it is possible to better balance the solvent stability and ion diffusion rate requirements, and better improve the battery's cycle performance, capacity, rate performance and other comprehensive performance.

[0026] In some embodiments, at least a portion of the first gel electrolyte is located between the second gel electrolyte and the positive electrode tab, and at least a portion of the first gel electrolyte is also located between the second gel electrolyte and the negative electrode tab.

[0027] At this time, the first gel electrolyte is provided on both opposing surfaces of at least one set of the positive electrode sheet and the negative electrode sheet to form two opposing faces, and the second gel electrolyte is provided between the two opposing faces formed by the first gel electrolyte.

[0028] At this time, the cross-linking degree distribution of "positive electrode sheet surface-low cross-linking-high cross-linking area-low cross-linking-high cross-linking-negative electrode sheet surface" in which at least one group of relatively arranged positive electrode sheets and negative electrode sheets has a low cross-linking area on the electrode sheet surface and a high cross-linking area is set between the two opposite surfaces of the low cross-linking area can better optimize the comprehensive performance of the gel electrolyte battery in terms of capacity utilization, battery rigidity and safety.

[0029] In some embodiments, the gel electrolyte further includes a third gel electrolyte, which is located in at least a portion of the third region and the fourth region; wherein the third region is the gap region between the negative active materials in the negative electrode plate, and the fourth region is the gap region between the positive active materials in the positive electrode plate.

[0030] The gel electrolyte in the gel electrolyte battery can also be distributed in the void area in the active material layer of the electrode plate, which is beneficial to maintaining the ion transport in the pores inside the electrode plate and promoting the electrical contact and capacity of the active material particles.

[0031] In some embodiments, the mass ratio m of the gel portion of the first gel electrolyte to the gel portion of the third gel electrolyte is 1 / 3 It is 1:(4-10), can be optionally 1:(4-8), and can further be optionally 1:(4-6).

[0032] By adjusting the mass ratio of the gel portion of the first gel electrolyte to the gel portion of the third gel electrolyte, the distribution ratio of the gel electrolyte on the surface of the electrode plate and inside the electrode plate can be directly controlled, and the distribution ratio of the gel electrolyte outside the electrode plate and inside the electrode plate can be indirectly controlled, so that both the inside and the surface of the electrode plate have a relatively appropriate amount of gel electrolyte, and then a better wetting buffer layer is set between the active material layer of the electrode plate and the high stiffness layer between the electrode plates, which is conducive to achieving better performance of the battery capacity.

[0033] In some embodiments, at least a portion of the second gel electrolyte is in contact with the first gel electrolyte in at least a portion of the first region and the second region.

[0034] The gel electrolyte in the relative space between the electrode plates can be in direct contact with the gel electrolyte on the surface of the electrode plates, which is beneficial to maintaining good ion transmission and low solution impedance during battery use, thereby achieving better battery performance.

[0035] In some embodiments, the electrode assembly further includes a separator, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet, and the second gel electrolyte is located outside the separator.

[0036] In some embodiments, the gel electrolyte further includes a fourth gel electrolyte, and the fourth gel electrolyte is located in the inner pores of the separator.

[0037] In some embodiments, the mass ratio m of the gel portion of the second gel electrolyte to the gel portion of the fourth gel electrolyte is 2 / 4 It is (4-9):1, can be optionally (5-9):1, and can further be optionally (6-8):1.

[0038] The inclusion of gel electrolyte within the separator's internal pores can further enhance separator strength, inhibit thermal shrinkage, maintain ionic conductivity, and improve battery safety. By adjusting the ratio of the gel electrolyte content within the relative spacing between the electrode plates and within the separator, the gel electrolyte content within the separator can be optimally controlled, further optimizing these effects.

[0039] In some embodiments, the gel electrolyte battery further comprises a shell, wherein the electrode assembly and the electrolyte are both located inside the shell;

[0040] The electrolyte may also include or exclude a fifth gel electrolyte, and may include or exclude a sixth gel electrolyte, wherein the fifth gel electrolyte is located at least a portion of the outermost surface of the electrode assembly, and the sixth gel electrolyte is located at at least a portion of the relative space between the outermost surface of the electrode assembly and the inner wall of the shell, and the cross-linking degree of the sixth gel electrolyte is higher than that of the fifth gel electrolyte.

[0041] A gel electrolyte can be arranged between the electrode assembly and the battery shell to provide rigid protection for the periphery of the electrode assembly and further improve the overall rigidity of the gel electrolyte battery. The low cross-linking degree of the outermost surface of the electrode assembly combined with the high cross-linking degree between the electrode assembly and the shell can form the first gel electrolyte and the second gel electrolyte at the same time.

[0042] In some embodiments, the ratio of the sum of the mass m5 of the gel portion of the fifth gel electrolyte and the mass m6 of the gel portion of the sixth gel electrolyte to the sum of the mass m1 of the gel portion of the first gel electrolyte and the mass m2 of the gel portion of the second gel electrolyte satisfies 0≤(m5+m6) / (m1+m2)≤12.5%, optionally satisfies 0≤(m5+m6) / (m1+m2)≤10%, further optionally satisfies 4%≤(m5+m6) / (m1+m2)≤12.5%, further optionally satisfies 5%≤(m5+m6) / (m1+m2)≤12.5%, and further optionally satisfies 5%≤(m5+m6) / (m1+m2)≤10%.

[0043] By controlling the ratio of the gel electrolyte outside the electrode assembly (including the fifth gel electrolyte on the outermost surface of the electrode assembly and the sixth gel electrolyte between the electrode assembly and the shell, corresponding to m5+m6) to the gel electrolyte outside the electrode plate in the electrode assembly area (including the first gel electrolyte on the surface of the electrode plate and the second gel electrolyte in at least a part of the relative space between the electrode plates, corresponding to m1+m2), the gel electrolyte outside the electrode assembly can be controlled within a certain range, which can not only provide a certain rigid protection for the periphery of the electrode assembly, but also provide sufficient gel electrolyte in the area where the electrode assembly is located, maintaining good battery capacity performance while providing higher battery rigidity, and can also play a role in effectively transmitting active ions during the charge and discharge cycle of the battery.

[0044] In some embodiments, the electrolyte further comprises or does not comprise a liquid electrolyte;

[0045] Optionally, the mass ratio of the gel portion of the gel electrolyte to the liquid electrolyte is 1:(0-0.05), further optionally 1:(0.01-0.05), and further optionally 1:(0.02-0.04).

[0046] Introducing gel electrolyte into gel electrolyte batteries can improve the overall rigidity of the battery while retaining the traditional liquid electrolyte. At this time, the interfacial wetting contact between the active material and the gel electrolyte can be improved, and the electrolyte consumption during the cycle can be replenished, thereby improving the long-term cycle performance of the battery.

[0047] In some embodiments, the positive electrode sheet comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material comprises a lithium ion material;

[0048] Optionally, the gel electrolyte includes a lithium salt; further optionally, the electrolyte salts in the first gel electrolyte and the second gel electrolyte each independently include a lithium salt;

[0049] Optionally, the electrolyte comprises a lithium salt in a liquid electrolyte.

[0050] When the active ions in a gel electrolyte battery include lithium ions, the electrolyte salts in the gel electrolyte and the liquid electrolyte can each independently contain a lithium salt that is more compatible with the active ions to better transport the active ions. Furthermore, the electrolyte salts in the first gel electrolyte and the second gel electrolyte can each independently contain a lithium salt, which is conducive to better transporting the active ions.

[0051] In a second aspect, the present application provides a method for preparing a gel electrolyte battery, which comprises the following steps:

[0052] The electrode assembly is installed in the housing, wherein the electrode assembly includes a positive electrode sheet, a separator and a negative electrode sheet, and the separator is arranged between the positive electrode sheet and the negative electrode sheet;

[0053] Injecting a first injection material into the housing, wherein the first injection material includes a first electrolyte salt, a first polymerizable monomer, and a first solvent;

[0054] Carry out chemical formation;

[0055] curing the first injection material to form a first gel electrolyte on at least a portion of the surface of the positive electrode sheet and the negative electrode sheet;

[0056] injecting a second liquid injection material into the housing, wherein the second liquid injection material includes a second electrolyte salt, a second polymerizable monomer, and a second solvent;

[0057] The second injection material is subjected to a curing reaction to form a second gel electrolyte in at least a portion of the relative space between the positive electrode plate and the negative electrode plate; wherein the crosslinking degree of the gel portion of the second gel electrolyte is higher than the crosslinking degree of the gel portion of the first gel electrolyte.

[0058] By adding polymerizable monomers to the electrolyte raw material, a gel electrolyte can be formed through a curing reaction. The liquid raw material of the electrolyte is further injected and cured in steps. After the first injection, the first gel electrolyte is formed on the surface of the electrode plate after formation and the first curing. Then, the second injection and curing are performed to form a second gel electrolyte in at least a part of the relative space between the electrode plates (or the second gel electrolyte is formed on the side of the first gel electrolyte away from the surface of the electrode plate). By controlling the cross-linking degree of the gel electrolyte formed in different curing steps, the gel electrolyte can be formed in a gradient and coordinated cross-linking degree at different positions of the battery. By controlling the second gel electrolyte The cross-linking degree of the gel part of the gel electrolyte is higher than the cross-linking degree of the gel part of the first gel electrolyte, and the gel electrolyte battery of the first aspect of the present application can be prepared, wherein the gel electrolyte can have a synergistic distribution of low cross-linking on the surface of the electrode plate and high cross-linking in the relative space of the electrode plate. On the one hand, the surface of the electrode plate with low cross-linking degree can absorb and swell more liquid electrolyte, thereby having better infiltration in the pores and surface of the electrode plate, which is more conducive to the performance of electrical properties such as capacity. On the other hand, the design of high cross-linking degree in the relative space of the electrode plate can give the battery higher rigidity, further enhance the ability of the battery to resist deformation during use, thereby significantly improving the safety performance of the battery cell.

[0059] In some embodiments, the mass concentration of the first polymerizable monomer in the first injection material is recorded as c1, and the mass concentration of the second polymerizable monomer in the second injection material is recorded as c2, wherein c1 <c2;

[0060] Optionally, the mass concentration of the first polymerizable monomer in the first injection material is 2% to 6%, and further optionally 3% to 5%;

[0061] Alternatively, the mass concentration of the second polymerizable monomer in the second injection material is 5% to 10%, and further optionally 8% to 10%.

[0062] In some embodiments, the mass ratio of the first injection material to the second injection material is (1-9):1;

[0063] Optionally, the mass ratio of the first injection material to the second injection material is (2-6):1.

[0064] The coordinated design of low cross-linking on the surface of the electrode plates and high cross-linking in the relative space of the electrode plates in the obtained gel electrolyte battery, or the design of sequentially setting low cross-linking areas and high cross-linking areas on the surface of the electrode plates, can be achieved by controlling the polymerization monomer concentration (such as mass concentration c2) in the injection material during the second injection to be higher than the polymerization monomer concentration (such as mass concentration c1) in the injection material during the first injection. Furthermore, the polymerization monomer concentration during the two injections can be adjusted to a more appropriate range, and the mass ratio of the two injections can also be adjusted, so as to better control the gel electrolyte in the battery to have a more appropriate gradient distribution and better balance the comprehensive performance of battery capacity and battery stiffness improvement.

[0065] In some embodiments, the gel electrolyte battery prepared by the preparation method is as defined in the first aspect of the present application.

[0066] In a third aspect, the present application provides an electrical device comprising at least one of the gel electrolyte battery described in the first aspect of the present application and the gel electrolyte battery prepared by the preparation method described in the second aspect of the present application.

[0067] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to better describe and illustrate the embodiments or examples of the applications disclosed herein, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed applications, the embodiments or examples currently described, and any of the best modes of these applications currently understood. Moreover, the same figure numbers are used to represent the same components in all the drawings. It should also be noted that the drawings are drawn in a simplified form and are only used to assist in explaining the invention conveniently and clearly. The various dimensions of each component shown in the drawings are arbitrarily shown and may be accurate or not drawn to scale. For example, in order to make the illustrations clearer, the dimensions of the components are appropriately exaggerated in some places in the drawings. Unless otherwise specified, the components in the drawings are not drawn to scale. The present invention does not limit every dimension of every component.

[0069] In the attached figure:

[0070] FIG1 is a schematic diagram of the distribution of the gel electrolyte in a gel electrolyte battery according to an embodiment of the present application, showing an electrode plate 100, a first gel electrolyte 410 located on one side of the electrode plate 100, and a second gel electrolyte 420 located away from the electrode plate 100 from the first gel electrolyte 410; the first gel electrolyte is located between the second gel electrolyte and an electrode plate;

[0071] FIG2 is a schematic diagram showing a cross-linking gradient distribution of a gel electrolyte outside an electrode plate in one embodiment of the present application, showing one side of an electrode plate as a non-limiting example, wherein an electrode plate 100, a first gel electrolyte 410 located on both sides of the electrode plate, and a second gel electrolyte 420 located on a side of the first gel electrolyte 410 away from the electrode plate 100 are shown; the second gel electrolyte 420 is located on both sides of the electrode plate 100;

[0072] FIG3 is a schematic diagram showing a cross-linking gradient distribution of a gel electrolyte in an electrode assembly region according to an embodiment of the present application. The diagram shows an electrode assembly comprising a positive electrode sheet 110, a negative electrode sheet 120, and a separator 200, wherein the separator 200 is located between the positive electrode sheet 110 and the negative electrode sheet 120. The diagram also shows a first gel electrolyte 410 located on two opposing surfaces of the positive electrode sheet 110 and the negative electrode sheet 120, and a second gel electrolyte 420 located in at least a portion of the opposing space between the positive electrode sheet 110 and the negative electrode sheet 120, with the second gel electrolyte 420 located outside the separator 200. In this embodiment, the second gel electrolyte 420 is located between the opposing positive electrode sheet 110 and the negative electrode sheet 120, and the first gel electrolyte 410 is located at least between the second gel electrolyte 420 and the positive electrode sheet 110 and at least between the second gel electrolyte 420 and the negative electrode sheet 120.

[0073] FIG4 is a schematic diagram of an embodiment of the present application in which a gel electrolyte is distributed both outside and in the internal void region of an electrode plate, showing the electrode plate and a first gel electrolyte 410 located on both sides of the electrode plate, and a second gel electrolyte 420 distributed on both sides of the electrode plate and located on both sides of the first gel electrolyte 410 and away from the electrode plate. The electrode plate includes a current collector 101, an active material layer 103 located on both sides of the current collector 101, the active material layer 103 including granular active substances 1031, a void region between the granular active substances 1031 of the active material layer 103, and a third gel electrolyte 430 located in the void region.

[0074] FIG5 is a schematic diagram of a gel electrolyte distributed outside the separator and in the internal pores of the separator in one embodiment of the present application, wherein the positive electrode sheet 110, the negative electrode sheet 120, and the separator 200 located between the positive electrode sheet 110 and the negative electrode sheet 120 are shown. A first gel electrolyte 410 is present on both opposing surfaces of the positive electrode sheet 110 and the negative electrode sheet 120, and a second gel electrolyte 420 is present in at least a portion of the relative space between the positive electrode sheet 110 and the negative electrode sheet 120. The second gel electrolyte 420 is located between the first gel electrolyte 410 and the negative electrode sheet 120. 0 is located in at least a portion of the relative space between two opposing surfaces of the positive electrode sheet 110 and the negative electrode sheet 120, and the second gel electrolyte 420 is located outside the separator 200; the separator 200 includes separator particles 201 and a fourth gel electrolyte 440 distributed in at least a portion of the pores between the separator particles 201; in this embodiment, at least a portion of the first gel electrolyte 410 is located between the second gel electrolyte 420 and the positive electrode sheet 110, and at least a portion is also located between the second gel electrolyte 420 and the negative electrode sheet 120;

[0075] FIG6 is a longitudinal cross-sectional view (left side) and a partial enlarged view of the longitudinal cross-sectional view (right side) of a gel electrolyte battery in one embodiment of the present application. The four areas distinguished by vertical solid lines in the longitudinal cross-sectional view on the left side represent two bare battery cells assembled by a winding structure, and the two bare battery cells are connected in parallel to the top cover through the adapter plate on the top; the partial enlarged view of the longitudinal cross-sectional view on the right side illustrates the stacking of the positive and negative electrode sheets and the separator in the bare battery cell, and shows in detail the distribution of the gel electrolyte in the shell 51. The gel electrolyte battery 5 includes a shell 51 and an electrode assembly. The electrode assembly includes a plurality of positive electrode sheets 110, a plurality of negative electrode sheets 120, and a plurality of separators 200 arranged between any group of relative positive electrode sheets 110 and negative electrode sheets 120, and at least one group of relative positive electrode sheets 110 and negative electrode sheets 120. A first gel electrolyte 410 is present on both opposing surfaces of the electrode sheet 120. A second gel electrolyte 420 is present on at least a portion of the opposing space between the aforementioned set of opposing positive electrode sheets 110 and negative electrode sheets 120. The second gel electrolyte 420 is located in at least a portion of the opposing space between the two opposing surfaces of the first gel electrolyte 410 away from the positive electrode sheet 110 and the negative electrode sheet 120. The second gel electrolyte 420 is located outside the corresponding separator 200 and between the two opposing surfaces of the first gel electrolyte 410. A fifth gel electrolyte 450 is present on the outermost surface of the electrode assembly, and a sixth gel electrolyte 460 is present in the area between the electrode assembly and the housing 51. The sixth gel electrolyte is located in the area of ​​the fifth gel electrolyte 450 away from the electrode assembly.

[0076] FIG7 is a schematic diagram of a gel electrolyte battery according to an embodiment of the present application;

[0077] FIG8 is an exploded view of the gel electrolyte battery according to an embodiment of the present application shown in FIG7 ;

[0078] FIG. 9 is a schematic diagram of an electrical device using a gel electrolyte battery as a power source according to an embodiment of the present application.

[0079] Explanation of the accompanying drawings: 100 is an electrode plate, 101 is a current collector, 103 is an active material layer, 1031 is an active substance (or active particles), 110 is a positive electrode plate, 120 is a negative electrode plate, 200 is an isolation membrane, 201 is isolation membrane particles, 410 is a first gel electrolyte, 420 is a second gel electrolyte, 430 is a third gel electrolyte, 440 is a fourth gel electrolyte, 450 is a fifth gel electrolyte, and 460 is a sixth gel electrolyte; 5 is a gel electrolyte battery, 51 is a shell, 52 is an electrode assembly, 53 is a cover plate, and 6 is an electrical device. DETAILED DESCRIPTION

[0080] The following describes in detail, with appropriate reference to the accompanying drawings, some embodiments of the gel electrolyte battery, electrical device, and preparation method disclosed herein. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is done to avoid unnecessary length in the following description and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to facilitate a thorough understanding of the present application by those skilled in the art and are not intended to limit the subject matter described in the claims.

[0081] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are also listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on. For example, when a parameter is expressed as an integer selected from "2-10", this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0082] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0083] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of such phrases in various locations in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive with other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments. References to "implementations" herein have a similar understanding.

[0084] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0085] Unless otherwise specified, the terms "include," "contain," and "comprise" used in this application are open-ended or closed-ended. For example, "include" and "comprise" can mean that other elements or temporal features not listed are also included, or that only the listed elements or temporal features are included. Elements include materials or components, structures, elements, and instruments; non-limiting examples of temporal features include actions, conditions for the occurrence of actions, timing, and states.

[0086] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "either A, B, or both A and B." Furthermore, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0087] In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0088] In this application, unless otherwise specified, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. The features or solutions corresponding to "and / or" include any one of two or more related listed items, and also include any and all combinations of the related listed items, and the arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a group consisting of A, B, and "a combination of A and B." Among them, "including A and / or B" can mean "including A, including B, and including A and B", and can also mean "including A, including B, or including A and B", which can be appropriately understood according to the sentence in which it is located.

[0089] In this application, references to "plurality," "multiple," and the like, unless otherwise specified, refer to a quantity greater than or equal to two. For example, "one or more" refers to one or greater than or equal to two. It is understood that references to "any number" of items refer to any suitable combination of multiple items, i.e., any combination of "any number" of items that is consistent with the present application and that allows for the implementation of the present application.

[0090] The terms "combination thereof", "any combination thereof", "any combination thereof" and the like used in this application include all suitable combinations of any two or more of the listed items.

[0091] In this application, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the technical solution that can implement this application.

[0092] In this application, the terms "preferred," "better," "more preferred," and "suitable" are used solely to describe preferred implementations or examples and should not limit the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, each "preferred" term is independent unless otherwise specified and there are no contradictions or mutual constraints.

[0093] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0094] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0095] In this application, the terms "first," "second," "third," "fourth," etc. in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description, and should be understood not to constitute a closed-ended limitation on quantity.

[0096] In this application, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, and may refer to 20°C ± 5°C. In some embodiments of this application, room temperature or normal temperature refers to 20°C to 30°C, for example, 25°C.

[0097] In this application, when referring to a data range, if the unit is only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 3~5h or 3-5h both mean that the units of the left endpoint "3" and the right endpoint "5" are both hours.

[0098] The weights of the relevant components mentioned in the examples of this application may not only refer to the content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Furthermore, the weights mentioned in the examples of this application may be mass units known in the chemical industry, such as μg, mg, g, and kg.

[0099] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, when understood in conjunction with the accompanying drawings, it can be understood as being based on the orientation or positional relationships shown in the drawings.

[0100] In this application, unless otherwise specified, "a group of opposite positive pole sheets and negative pole sheets" or "a group of oppositely arranged positive pole sheets and negative pole sheets" means that a relative space of this group of opposite positive pole sheets and negative pole sheets is formed on one side surface of the positive pole sheet and one side surface of the negative pole sheet, and there are no other electrode pole sheets in this relative space, but an isolation membrane is usually provided.

[0101] In the present application, “low cross-linking” means “low degree of cross-linking”, and “high cross-linking” means high degree of cross-linking.

[0102] In this application, the phrases "the first gel electrolyte is located on the surface of the electrode plate" and "the first gel electrolyte is located on the surface of the electrode plate" have the same meaning. Unless otherwise specified, at least a portion of the first gel electrolyte directly covers the surface of the electrode plate.

[0103] In the present application, the phrase “A is located on one side of B” only indicates the position direction of A relative to B, and A and B may not be in direct contact.

[0104] During use, secondary batteries may be accidentally impacted or subjected to stress, which may cause deformation of the secondary battery, resulting in damage, breakage, or dislocation of the internal components of the battery. This will not only affect the service life of the secondary battery, but may also cause the battery to short-circuit or leak, affecting the safety of the secondary battery. By introducing a gel electrolyte into the electrolyte of the secondary battery, the rigidity of the battery can be improved, and to a certain extent, the impact resistance of the battery can be improved. However, the introduced gel electrolyte may affect the infiltration of the electrolyte into the electrode plate, thereby affecting the transmission and deintercalation efficiency of the active ions. It may also cause polarization on the surface of the electrode plate, affecting the performance of electrical properties such as battery capacity.

[0105] To address the above-mentioned technical issues, in a first aspect, the present application provides a gel electrolyte battery comprising at least one electrode plate 100, a first gel electrolyte 410 located on at least one side of the electrode plate 100, and a second gel electrolyte 420 located away from the first gel electrolyte 410. The gel portion of the second gel electrolyte 420 has a higher degree of crosslinking than the gel portion of the first gel electrolyte 410. In this case, the first gel electrolyte is located between the second gel electrolyte and an electrode plate. The electrode plate can be a positive electrode plate or a negative electrode plate. See Figure 1.

[0106] The second gel electrolyte 420 may be located on one side or both sides of the electrode pad 100 .

[0107] In one embodiment, a gel electrolyte battery having a gel electrolyte distribution as shown in FIG2 includes at least one electrode plate 100, a first gel electrolyte 410 located on both side surfaces of the electrode plate, and a second gel electrolyte 420 located on the side of the first gel electrolyte 410 away from the electrode plate 100; the second gel electrolyte 420 is located on both sides of the electrode plate 100.

[0108] In the first aspect of the present application, another gel electrolyte battery is provided, which includes a positive electrode plate 110, a negative electrode plate 120 and a gel electrolyte; the gel electrolyte includes a first gel electrolyte 410 located in at least a portion of the surface of the positive electrode plate and the surface of the negative electrode plate, and also includes a second gel electrolyte 420 located in at least a portion of the relative space between the positive electrode plate and the negative electrode plate; the cross-linking degree of the gel portion of the second gel electrolyte is higher than the cross-linking degree of the gel portion of the first gel electrolyte.

[0109] It is understood that when gel electrolytes with different crosslinking degrees are disposed between a pair of oppositely positioned positive and negative electrode sheets, the first gel electrolyte and the second gel electrolyte can be easily distinguished. In this case, the first gel electrolyte is located between the second gel electrolyte and at least one electrode sheet, and the first gel electrolyte is distributed in at least a portion of the area between the second gel electrolyte and the positive electrode sheet and the area between the second gel electrolyte and the negative electrode sheet.

[0110] Both of the aforementioned two gel electrolyte batteries include gel electrolytes with a coordinated combination of high and low cross-linking degrees, which can give the battery higher rigidity and improve battery safety while maintaining good battery capacity.

[0111] In some embodiments, a gel electrolyte battery is provided, comprising an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode sheet and a negative electrode sheet; the electrolyte comprises a gel electrolyte, and the gel electrolyte comprises a first gel electrolyte and a second gel electrolyte; the first gel electrolyte is located in at least a portion of at least one side surface of at least one electrode sheet, and the second gel electrolyte is located on a side of the first gel electrolyte away from the electrode sheet; the electrode sheet is the positive electrode sheet or the negative electrode sheet;

[0112] The cross-linking degree of the gel portion of the second gel electrolyte is higher than the cross-linking degree of the gel portion of the first gel electrolyte.

[0113] In the aforementioned gel electrolyte battery, the gel electrolyte in the battery cell can improve the rigidity of the secondary battery. Furthermore, a combination distribution of a first gel electrolyte with a low degree of cross-linking (located on at least one side of the electrode plate) and a second gel electrolyte with a high degree of cross-linking and high rigidity (separated from the surface of the electrode plate by the first gel electrolyte) is formed in sequence on the surface of the electrode plate. On the one hand, the surface of the electrode plate with a low degree of cross-linking can absorb and swell more liquid electrolyte, thereby having better infiltration in the pores and surface of the electrode plate, which is more conducive to the performance of electrical properties such as capacity. On the other hand, the high degree of cross-linking design away from the electrode surface can give the battery higher rigidity, further enhance the battery's ability to resist deformation during use, thereby significantly improving the safety performance of the battery cell.

[0114] In some embodiments, another gel electrolyte battery is provided, comprising an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode sheet and a negative electrode sheet; the electrolyte comprises a gel electrolyte, and the gel electrolyte comprises a first gel electrolyte and a second gel electrolyte;

[0115] The first gel electrolyte is located in at least a portion of a first region and a second region: wherein the first region is the surface region of the negative electrode sheet, and the second region is the surface region of the positive electrode sheet;

[0116] The second gel electrolyte is located in at least a portion of the relative space between the positive electrode sheet and the negative electrode sheet;

[0117] The cross-linking degree of the gel portion of the second gel electrolyte is higher than the cross-linking degree of the gel portion of the first gel electrolyte.

[0118] In the aforementioned gel electrolyte battery, a gel electrolyte having a gradient cross-linking distribution on the surface of the electrode plate and between the electrode plates can improve the stiffness of the secondary battery. Furthermore, a first gel electrolyte with a low cross-linking degree is arranged on the surface of the electrode plate, and a second gel electrolyte (high stiffness layer) with a high cross-linking degree is arranged in at least a portion of the relative space between the positive and negative plates. The gel electrolyte is controlled to have a coordinated distribution of low cross-linking on the surface of the electrode plate and high cross-linking in the relative space of the electrode plates. On the one hand, the surface of the electrode plate with a low cross-linking degree can absorb and swell more liquid electrolyte, thereby having better infiltration in the pores and surface of the electrode plate, which is more conducive to the performance of electrical properties such as capacity. On the other hand, the design of high cross-linking degree in the relative space of the electrode plates can give the battery higher stiffness, further enhance the battery's ability to resist deformation during use, thereby significantly improving the safety performance of the battery cell.

[0119] The gel electrolyte battery provided in the first aspect of the present application is a secondary battery including a gel electrolyte.

[0120] In this application, unless otherwise specified, the electrode plate can be a positive electrode plate or a negative electrode plate. The "active material" in the electrode plate refers to a substance that can reversibly embed and release active ions; since the active material is usually in granular form, it is also called "active particles". Unless otherwise specified, "negative electrode active material" refers to a substance used in the negative electrode plate that can reversibly embed and release active ions, also known as negative electrode active material or negative electrode active particles; "positive electrode active material" refers to a substance used in the positive electrode plate that can reversibly release and embed active ions, also known as positive electrode active material or positive electrode active particles. When the secondary battery is charged, the active ions are released from the positive electrode and embedded in the negative electrode through the electrolyte; when the secondary battery is discharged, the active ions are released from the negative electrode and embedded in the positive electrode. The active ions are not particularly limited and can be lithium ions. When the active ions are mainly lithium ions, it is a lithium-ion secondary battery.

[0121] In this application, "active material" and "active substance" have the same meaning and can be used interchangeably. Active materials are generally granular and can also be called "active particles"; "positive electrode active substance" and "positive electrode active material" have the same meaning and can be used interchangeably; "negative electrode active substance" and "negative electrode active material" have the same meaning and can be used interchangeably.

[0122] In this application, unless otherwise specified, "active material layer" includes at least one of the positive electrode active material layer of the positive electrode sheet and the negative electrode active material layer of the negative electrode sheet. Depending on the specific circumstances, it can refer to either the positive electrode active material layer or the negative electrode active material layer. It is understood that the positive electrode active material layer contains a positive electrode active material, and the negative electrode active material layer contains a negative electrode active material.

[0123] The gel electrolyte battery provided in the first aspect of the present application includes at least a positive electrode sheet, a negative electrode sheet, and an electrolyte. The electrolyte functions to conduct active ions between the positive and negative electrode sheets. The electrolyte includes at least a gel electrolyte, and the gel electrolyte is distributed on at least a portion of the surface of at least one electrode sheet and at least a portion of the space between the positive and negative electrode sheets. The gel electrolyte located on the surface of the electrode sheet is referred to as the first gel electrolyte, and the gel electrolyte located in at least a portion of the space between the positive and negative electrode sheets is referred to as the second gel electrolyte. The first gel electrolyte can be distributed on at least one side of the electrode sheet, either on one or both sides. The second gel electrolyte is distributed in at least a portion of the space between at least one pair of opposing positive and negative electrode sheets. A separator can be provided between the opposing positive and negative electrode sheets. In the present application, unless otherwise specified, the gel portion of the second gel electrolyte has a higher degree of crosslinking than the gel portion of the first gel electrolyte.

[0124] In the context of the present application, the terms "first", "second", "third", "fourth", "fifth" and "sixth" in "first gel electrolyte", "second gel electrolyte", "third gel electrolyte", "fourth gel electrolyte", "fifth gel electrolyte" and "sixth gel electrolyte" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or quantity, nor are they to be understood as implicitly indicating the importance or quantity of the indicated technical features.

[0125] In this application, a "gel electrolyte" refers to a semi-solid electrolyte with the following characteristics: it comprises a gel skeleton, a gelling solvent located within the gel skeleton region, and an electrolyte salt dissolved in the gelling solvent. The gel skeleton is a cross-linked polymer with a three-dimensional network structure; the gelling solvent is bounded within the mesh of the gel skeleton and cannot flow freely, resulting in the electrolyte in the gel skeleton region being a colloidal semi-solid state; the gelling solvent has a relatively continuous distribution within the gel skeleton, and the electrolyte solvent in the gel electrolyte is dissolved within the gelling solvent. With the restricted movement of the chain segments between the crosslinks in the network structure, the electrolyte salt can conduct active ions. In addition, the molecular segments between adjacent crosslinks in the gel skeleton still have a certain degree of flexibility, giving the network structure not only a certain degree of support but also a certain degree of elasticity. However, the chain segments between these crosslinks are confined between the corresponding nodes of the mesh and cannot diffuse freely in the solvent like free molecules. Therefore, in terms of physical form, the gel electrolyte combines the solidity of the gel skeleton with the restricted fluidity of the gelling solvent, which is significantly different from traditional electrolytes that are free-flowing and have no fixed shape.

[0126] In this application, "liquid electrolyte" is a liquid electrolyte, also called an electrolyte, which includes an electrolyte salt and a solvent. The solvent is free-flowing, and the electrolyte salt dissolved in the solvent is free-migrating. The liquid electrolyte as a whole is free-flowing and has no fixed shape.

[0127] It can be understood that the mobility of the electrolyte salt in the gel electrolyte is lower than that in the liquid electrolyte.

[0128] In this application, "cross-linked polymer" has the well-known meaning in the field of polymer technology. It has a three-dimensional network structure and can produce a certain degree of swelling in the corresponding solvent, but will not dissolve. The degree of swelling depends on the degree of cross-linking of the cross-linked polymer.

[0129] In the application, unless otherwise specified, the "gel portion of the gel electrolyte" refers to the gel skeleton portion of the gel electrolyte, excluding the solvent, electrolyte salt and other optional components in the gel electrolyte.

[0130] In this application, "crosslinking degree" refers to the degree of cross-linking between molecular chains of a cross-linked polymer having a three-dimensional network structure. The nodes that constitute the three-dimensional network structure are also crosslinking points. The degree of crosslinking can be characterized by one or more parameters including crosslinking point density p, effective chain average molecular weight M between crosslinking points, swelling degree, volume swelling degree, weight swelling ratio, thermal decomposition temperature Td, and glass transition temperature Tg.

[0131] Unless otherwise specified, "crosslink density" (ρ) represents the fraction of crosslinked structural units to the total structural units, i.e., the crosslink probability of each structural unit. A higher crosslink density indicates a higher degree of crosslinking.

[0132] Unless otherwise specified, the lower the effective chain average molecular weight M between the cross-linking points, that is, the shorter the molecular chain segments between the cross-linking points, the denser the distribution of the cross-linking points, and the higher the degree of cross-linking.

[0133] Unless otherwise specified, "swelling degree" refers to the degree of polymer swelling and can be expressed as the volume ratio or weight ratio before and after swelling, such as volume swelling degree and weight swelling rate. Unless otherwise specified, volume swelling degree refers to the ratio of the volume of the polymer at equilibrium after adsorption of solvent molecules to the volume before swelling. Unless otherwise specified, weight swelling rate refers to the ratio of the weight of the polymer at equilibrium after adsorption of solvent molecules to the dry weight before swelling.

[0134] In this application, the "swelling rate" referred to is determined by weight method and is numerically equal to the weight swelling rate unless otherwise specified.

[0135] When solvent molecules enter the three-dimensional network of the cross-linked polymer, they will cause the three-dimensional molecular network to stretch, causing the polymer to expand in volume and generate swelling force. At the same time, as the cross-linked network stretches, the conformational entropy of the polymer segments between the cross-linking points will decrease, causing the cross-linked network to generate elastic contraction force. The magnitude of this contraction force depends on the average molecular weight of the polymer segments between two adjacent cross-linking points in the cross-linked polymer. When the swelling force of the solvent and the contraction force of the segments between the cross-linking points are balanced, the cross-linked system reaches a swelling equilibrium state. According to the volume V at the swelling equilibrium, S The volume swelling value of the cross-linked polymer can be obtained by the ratio of the volume before measurement V0 = V S / V0, based on the weight W at swelling equilibrium S and the dry weight of the sample to be tested W d The weight swelling ratio of the cross-linked polymer can be obtained by the ratio of W S / W d The average molecular weight of the polymer chain segments between the polymer cross-linking points can also be calculated according to conventional methods.

[0136] The lower the cross-linking degree of the polymer, the longer the molecular chain segments between the cross-linking points, and the higher the swelling degree; conversely, the higher the cross-linking degree, the shorter the molecular chain segments between the cross-linking points, and the lower the swelling degree.

[0137] In this application, unless otherwise specified, the following method can be used to obtain a sample to be tested for testing the crosslinking degree and related parameters of the "gel portion of the gel electrolyte": a gel electrolyte sample is obtained from a specified position of a secondary battery (the gel electrolyte battery provided in this application), freeze-dried, and subjected to washing and solid-liquid separation operations to remove the electrolyte salt, solvent and other optional components and liquid electrolyte in the gel electrolyte, and the remaining gel skeleton is collected to obtain a gel sample of the "gel portion of the gel electrolyte".

[0138] Unless otherwise specified, the crosslinking degree test method in GB / T 18474-2001 may be referenced. Test parameters may also be adjusted appropriately based on the characteristics of the sample in this application. The crosslinking degree of the "gel portion of the gel electrolyte" may be tested using the following method: First, weigh the initial mesh bag (W1), add the sample to the mesh bag, seal it, and make a sample bag, weighing the total weight (W2). Then, add a solvent (non-limitingly, xylene may be selected, but not limited to) to a flask, immerse the sample bag in the solvent, heat and extract it, volatilize the solvent with the uncrosslinked monomer, and leave a crosslinked residual polymer sample. After drying, weigh the total weight (W3) of the crosslinked polymer sample and mesh bag. Wherein, the crosslinking degree = (W3 - W1) / (W2 - W1) × 100%; where W1 is the initial mesh bag weight, W2 is the total weight of the sample and mesh bag before extraction, and W3 is the total weight of the sample and mesh bag after extraction and drying.

[0139] If not otherwise specified, the weight swelling rate of the “gel portion of the gel electrolyte” can be tested by the following method: weigh the dried gel sample (to obtain the sample dry weight W d ), then soak the sample in the electrolyte at room temperature until swelling equilibrium (e.g., soak for at least 24 hours), and take samples at different time points according to multiple parallel samples. After swelling, the weight of the sample is basically no longer changed. Take out the sample from the electrolyte, remove the electrolyte on the surface with filter paper, and weigh it to obtain the weight of the sample after swelling equilibrium W S The swelling ratio of the sample to be tested is calculated by the following formula: Swelling ratio (by weight) = W S / W d , where W S is the weight of the sample after swelling equilibrium, W d is the dry weight of the sample.

[0140] If there is no other explanation, the following method can be used to test the volume swelling degree of the “gel part of the gel electrolyte”: the volume V of the dried gel sample is measured. d Then, immerse the sample in the electrolyte at room temperature until swelling equilibrium occurs (e.g., soak for at least 24 hours). Samples can be taken at different time points based on multiple parallel samples. After swelling, the volume of the sample is basically no longer changed. The sample is taken out of the electrolyte, and the surface electrolyte is removed with filter paper. The volume is measured to obtain the sample volume after swelling equilibrium V S The volume swelling degree of the sample to be tested is calculated by the following formula: Volume swelling degree = V S / V d , where V S is the volume of the sample after swelling equilibrium, V d is the volume of the sample in dry state.

[0141] It is understood that when comparing the swelling degrees of different gel samples, the samples are immersed in an electrolyte with the same composition. The electrolyte can refer to the composition of the other components of the gel electrolyte except the gel skeleton, and can be mainly composed of a solvent and an electrolyte salt, and may or may not include additive components.

[0142] In this application, unless otherwise specified, "glass transition temperature (Tg)" has a well-known meaning in the field of polymer technology, and refers to the temperature corresponding to the transition from a glassy state to a highly elastic state. For cross-linked polymers (such as the gel skeleton of the gel electrolyte in this application or the corresponding gel sample), the lower the degree of cross-linking, the lower the Tg temperature, and the higher the degree of cross-linking, the higher the Tg temperature. The glass transition temperature of the sample can be tested using differential scanning calorimetry (DSC) or static thermomechanical analysis (TMA). The glass transition temperature of a material measured by DSC is determined by measuring the change in the specific heat capacity of the material with temperature. The specific heat capacity will change significantly before and after Tg, and the numerical value of the glass transition temperature can be determined based on the curve. The TMA method is based on the fact that a polymer exhibits different deformations at different temperatures under the action of a certain external force. On the temperature-deformation curve, a significant turning point will occur at the glass transition temperature, from which the numerical value of the glass transition temperature can be determined.

[0143] In this application, unless otherwise specified, "thermal decomposition temperature (Td)" has a well-known meaning in the field of polymer technology, which refers to the temperature at which polymer molecules begin to crack, at which temperature the material will fail. For cross-linked polymers (such as the gel skeleton of the gel electrolyte in this application or the corresponding gel sample), the lower the degree of cross-linking, the worse the material stability, the lower the Td temperature, the higher the degree of cross-linking, the better the material stability, and the higher the Td temperature. Thermogravimetric mass spectrometry (TG-MS) can be used to simultaneously detect the weight change and component molecular weight change of the sample to analyze and obtain the thermal decomposition temperature Td of the sample. At Td, the polymer weight loss undergoes a significant turning point, and the molecular weight drops significantly due to molecular cracking.

[0144] In this application, unless otherwise specified, samples for DSC, DMA or TG-MS testing can be obtained in the following manner: the gel sample of the "gel portion of the gel electrolyte" prepared by the aforementioned method can be directly used for testing.

[0145] In the context of this application, the weight, volume, element distribution and other parameters of the gel electrolyte at different locations can be tested and analyzed based on focused electron beam (FIB) technology, scanning electron microscope (SEM) technology and elemental analysis technology. For example, it can be combined with focused electron beam (FIB) continuous sectioning, cross-section SEM morphology observation, energy dispersive spectroscopy (EDS) element spectrum and three-dimensional reconstruction analysis software analysis. For example, a frozen focused ion beam (FIB) is used to finely slice the sample (the smallest scale can reach nanometer-level thin slices), and the first gel electrolyte sample and the second gel electrolyte sample are separated. The morphology, structure and element distribution of each layer of the cross section can also be analyzed by scanning electron microscope SEM under FIB continuous sectioning. The three-dimensional structure of the sample can be reconstructed in combination with three-dimensional structure reconstruction software to estimate the mass and / or volume of the sample to be tested. The battery can be disassembled to obtain samples at different locations such as the active material layer sample of the electrode plate, the gel electrolyte sample on the surface of the electrode plate, and the gel electrolyte sample in the relative space area of ​​two oppositely arranged electrode plates, and then the above-mentioned method can be used to test parameters such as weight, volume and element distribution.

[0146] In some embodiments, the mass ratio m of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2 It can be expressed as the following numerical ratio s1:1,m 1 / 2 It can be (0.2-3):1, optionally (0.5-1):1, further optionally (0.79-1):1, and further optionally 1:1. 1 / 2 It can also be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 0.2:1, 0.25:1, 0.3:1, 1:3, 0.35:1, 0.4:1, 0.5:1, .6:1, 0.75:1, 0.79:1, 0.8:1, 0.9:1, 1:1, 1.25:1, 1.5:1, 2:1, 2.5:1, 3:1, etc., that is, the value s1 can be any of the following values, and can also be selected from the interval consisting of any two of the following values: 0.2, 0.25, 0.3, 1:3, 0.35, 0.4, 0.5, 0.6, 0.75, 0.79, 0.8, 0.9, 1, 1.25, 1.5, 2, 2.5, 3, etc.

[0147] In some embodiments, the volume ratio v of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2 It can be expressed as the following numerical ratio s2:1, v 1 / 2 It can be (0.2-3):1, optionally (0.5-1):1, further optionally (0.79-1):1, and further optionally 1:1. 1 / 2It can also be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 0.2:1, 0.25:1, 0.3:1, 1:3, 0.35:1, 0.4:1, 0.5:1, .6:1, 0.75:1, 0.79:1, 0.8:1, 0.9:1, 1:1, 1.25:1, 1.5:1, 2:1, 2.5:1, 3:1, etc., that is, the value s2 can be any of the following values, and can also be selected from the interval consisting of any two of the following values: 0.2, 0.25, 0.3, 1:3, 0.35, 0.4, 0.5, 0.6, 0.75, 0.79, 0.8, 0.9, 1, 1.25, 1.5, 2, 2.5, 3, etc.

[0148] In some embodiments, the crosslinking ratio CX of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2 It can be expressed as the following numerical ratio 1:s3, CX 1 / 2 It can be 1:(1-5), optionally 1:(1.1-2.0), further optionally 1:(1.5-2.0), and further optionally 1:(1.8-2.0). The value s3 can be any of the following values, and can also be selected from an interval consisting of any two of the following values: 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.75, 1.8, 2.0, 2.4, 2.5, 2.75, 3, 3.5, 3.6, 4, 4.5, 5, etc., that is, CX 1 / 2 It can also be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.75, 1:1.8, 1:2.0, 1:2.4, 1:2.5, 1:2.75, 1:3, 1:3.5, 1:3.6, 1:4, 1:4.5, 1:5, etc.

[0149] In some embodiments, the swelling ratio Q of the gel portion of the first gel electrolyte relative to the swelling ratio Q of the gel portion of the second gel electrolyte is 1 / 2 It can be expressed as the following numerical ratio s4:1, Q 1 / 2 It can be (1-4):1, optionally (1.3-2.5):1, further optionally (1.65-2.0):1, and further optionally (1.8-2.0):1. 1 / 2It can also be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.65:1, 1.7:1, 1.75:1, 1.8:1, 2.0:1, 2.4:1, 2.5:1, 2.75:1, 3:1, 3.5:1, 3.6:1, 4:1, etc.

[0150] In some embodiments, the thermal decomposition temperature ratio Td of the gel portion of the first gel electrolyte relative to the thermal decomposition temperature ratio Td of the gel portion of the second gel electrolyte is 1 / 2 It can be expressed as the following numerical ratio 1:s5, Td 1 / 2 It can be 1:(1-4), optionally 1:(1.1-2.0), further optionally 1:(1.45-2.0), and further optionally 1:(1.6-1.8). 1 / 2 It can also be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.45, 1:1.5, 1:1.6, 1:1.65, 1:1.7, 1:1.75, 1:1.8, 1:2.0, 1:2.4, 1:2.5, 1:2.75, 1:3, 1:3.5, 1:3.6, 1:4, etc.

[0151] m 1 / 2 and v 1 / 2 The lower the m, the higher the content of the second gel electrolyte, which is more beneficial to improving the battery stiffness. However, if m 1 / 2 and v 1 / 2 If one or both of the above are too low, the content of the second gel electrolyte will be too high, which may affect the filling space of the active material inside the battery and may reduce the energy density, or may cause the battery core to be too full and the internal stress to increase, which may lead to performance deterioration. On the other hand, if the content ratio of the first gel electrolyte is too low, it may lead to insufficient coverage of the first gel electrolyte with low cross-linking degree on the electrode surface, which may lead to poor electrode wetting effect and deterioration of electrical performance such as capacity utilization. 1 / 2 The lower, the Q 1 / 2 The higher or Td 1 / 2 The lower the mass ratio, the denser the network structure of the second gel electrolyte is, which is more conducive to providing a higher modulus, thereby being more beneficial to improving the rigidity of the battery. However, it may affect the amount of electrolyte retained between the electrodes, which may deteriorate the battery performance after long-term cycling. 1 / 2 , volume ratio v 1 / 2 , cross-linking degree ratio CX 1 / 2 , swelling ratio Q 1 / 2and thermal decomposition temperature ratio Td 1 / 2 By adjusting one or more parameters, the ratio of the first gel electrolyte to the second gel electrolyte can be controlled within a more appropriate range, and the synergistic combination between the low cross-linking on the surface of the electrode plate and the high cross-linking in the relative space of the electrode plate can be better coordinated, thereby better optimizing the comprehensive performance of the gel electrolyte battery in terms of capacity, battery stiffness and safety.

[0152] In some embodiments, the first gel electrolyte and the second gel electrolyte both contain electrolyte salt; the ratio f1 of the mass fraction of the electrolyte salt in the first gel electrolyte to f2 of the mass fraction of the electrolyte salt in the second gel electrolyte is f2. 1 / 2 The ratio is 1.5:1 to 1:1.5, and can be 1:(0.7-1.5), further 1:(0.8-1), and further 1:(0.8-0.95). 1 / 2 It can also be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 1.5:1, 1:0.67, 1:0.7, 1:0.75, 1:0.8, 1:0.9, 1:0.95, 1:1, 1:1.1, 1:1.2, 1::1.25, 1:1.3, 1:1.4, 1:1.45, 1:1.5, etc.

[0153] The ratio f1 of the mass fraction of the electrolyte salt in the first gel electrolyte to the mass fraction f2 of the electrolyte salt in the second gel electrolyte is 1 / 2 The higher the value, the higher the electrolyte salt concentration on the surface of the electrode plate, which is beneficial for more solvents to participate in solvation coordination, improve solvent stability, reduce side reaction consumption, and improve cycle performance. However, the concentration difference of electrolyte salt between the first gel electrolyte and the second gel electrolyte is too large, which may cause the ion diffusion rate between the first gel electrolyte and the second gel electrolyte to be mismatched, which may affect the capacity and rate performance.

[0154] In some embodiments, the gel electrolyte battery satisfies one or more of the following features:

[0155] The mass proportion f1 of the electrolyte salt in the first gel electrolyte is 0.7 to 1.2 mol / L, and can be optionally 0.8 to 1.2 mol / L;

[0156] The mass proportion f2 of the electrolyte salt in the second gel electrolyte is 0.7 to 1.2 mol / L, and can be optionally 0.8 to 1.2 mol / L.

[0157] In some embodiments, the mass fraction f1 of the electrolyte salt in the first gel electrolyte can be 0.7 to 1.2 mol / L, and can optionally be 0.8 to 1.2 mol / L. Non-limiting examples include 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, etc.

[0158] In some embodiments, the electrolyte salt mass fraction f2 in the second gel electrolyte may be 0.7 to 1.2 mol / L, and may be 0.8 to 1.2 mol / L, with non-limiting examples including 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, and 1.2 mol / L.

[0159] By controlling the concentration of the electrolyte salt in the first gel electrolyte and / or the second gel electrolyte within a certain range, the solvent stability and ion diffusion rate requirements can be better balanced, thereby better improving the battery's comprehensive performance, such as cycle performance, capacity, and rate performance.

[0160] In some embodiments, at least a portion of the first gel electrolyte is located between the second gel electrolyte and the positive electrode plate, and at least a portion of the first gel electrolyte is also located between the second gel electrolyte and the negative electrode plate. In this case, at least a portion of the first gel electrolyte and at least a portion of the second gel electrolyte are located between at least one set of opposing positive and negative electrode plates. In this case, the first gel electrolyte is disposed on both opposing surfaces of at least one set of opposing positive and negative electrode plates, forming two opposing surfaces, and the second gel electrolyte is disposed between the two opposing surfaces formed by the first gel electrolyte.

[0161] By adopting a cross-linking distribution pattern of "positive electrode sheet surface-low cross-linking-high cross-linking area-low cross-linking-high cross-linking-negative electrode sheet surface" in which a low cross-linking area is provided on the surface of the electrode sheet between at least one set of oppositely arranged positive electrode sheets and negative electrode sheets, and a high cross-linking area is provided between two opposite surfaces of the low cross-linking area, the comprehensive performance of the gel electrolyte battery in terms of capacity, battery rigidity and safety can be better optimized.

[0162] In one embodiment, a gel electrolyte battery has a gel electrolyte distribution as shown in FIG3 . The gel electrolyte battery includes an electrode assembly comprising a positive electrode sheet 110, a negative electrode sheet 120, and a separator 200, with the separator 200 positioned between the positive electrode sheet 110 and the negative electrode sheet 120. The gel electrolyte battery also includes a first gel electrolyte 410 positioned on opposing surfaces of the positive electrode sheet 110 and the negative electrode sheet 120, and a second gel electrolyte 420 positioned at least partially between the opposing space between the positive electrode sheet 110 and the negative electrode sheet 120, with the second gel electrolyte 420 positioned outside the separator 200. In this embodiment, at least a portion of the first gel electrolyte 410 and at least a portion of the second gel electrolyte 420 are positioned between the opposing positive electrode sheet 110 and the negative electrode sheet 120. At least a portion of the first gel electrolyte 410 is positioned between the second gel electrolyte 420 and the positive electrode sheet 110, and at least a portion is also positioned between the second gel electrolyte 420 and the negative electrode sheet 120.

[0163] In some embodiments, the gel electrolyte further includes a third gel electrolyte, which is located in at least a portion of the third region and the fourth region; wherein the third region is the gap region between the negative active materials in the negative electrode plate, and the fourth region is the gap region between the positive active materials in the positive electrode plate.

[0164] The gel electrolyte in the gel electrolyte battery can also be distributed in the gap area in the active material layer of the electrode plate, which is beneficial to promote the electrical contact and capacity of the active material particles.

[0165] In one embodiment, a gel electrolyte battery has a gel electrolyte distribution as shown in FIG4 . The gel electrolyte battery includes an electrode plate and a first gel electrolyte 410 located on both sides of the electrode plate, and a second gel electrolyte 420 distributed on both sides of the electrode plate and located on both sides of the first gel electrolyte 410 and away from the electrode plate. The electrode plate includes a current collector 101, an active material layer 103 located on both sides of the current collector 101, and the active material layer 103 includes granular active material 1031. There are void regions between the granular active material 1031 in the active material layer 103, and a third gel electrolyte 430 is located in the void regions.

[0166] In some embodiments, the mass ratio of the gel portion of the first gel electrolyte to the gel portion of the third gel electrolyte can be expressed as m 1 / 3 , can be expressed as the following numerical ratio 1:s6. m 1 / 3 It can be 1:(4-10), optionally 1:(4-8), and further optionally 1:(4-6). 1 / 3It can be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5, 1:10, etc.

[0167] By adjusting the mass ratio of the gel portion of the first gel electrolyte to the gel portion of the third gel electrolyte, the distribution ratio of the gel electrolyte on the surface of the electrode plate and inside the electrode plate can be directly controlled, and the distribution ratio of the gel electrolyte outside the electrode plate and inside the electrode plate can be indirectly controlled, so that both the inside and the surface of the electrode plate have a relatively appropriate amount of gel electrolyte, and then a better wetting buffer layer is set between the active material layer of the electrode plate and the high stiffness layer between the electrode plates, which is conducive to achieving better performance of the battery capacity.

[0168] In some embodiments, at least a portion of the second gel electrolyte is in contact with the first gel electrolyte in at least a portion of the first region and the second region.

[0169] The gel electrolyte in the relative space between the electrode plates can be in direct contact with the gel electrolyte on the surface of the electrode plates. At this time, it is beneficial to maintain good ion transmission and low solution impedance during battery use, thereby achieving better battery performance.

[0170] In some embodiments, the electrode assembly further includes a separator, wherein the separator is disposed between the positive electrode sheet and the negative electrode sheet, and the second gel electrolyte is located outside the separator.

[0171] In some embodiments, the gel electrolyte further includes a fourth gel electrolyte, and the fourth gel electrolyte is located in the inner pores of the separator.

[0172] In some embodiments, the mass ratio m of the gel portion of the second gel electrolyte to the gel portion of the fourth gel electrolyte is 2 / 4 It is (4-9):1, can be (5-9):1, and can be (6-8):1. 2 / 4 It can also be any of the following ratios or values, or be selected from an interval consisting of any two of the following ratios or values: 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, etc.

[0173] Gel electrolyte can be contained within the internal pores of the separator, which further enhances separator strength, suppresses thermal shrinkage, maintains ionic conductivity, and improves battery safety. By adjusting the ratio of the gel electrolyte content in the relative space between the electrode plates and within the separator, the gel electrolyte content within the separator can be rationally controlled, further optimizing the aforementioned effects.

[0174] In one embodiment, the gel electrolyte battery has a distribution pattern of the gel electrolyte as shown in FIG. 5 . The gel electrolyte battery includes a positive electrode sheet 110, a negative electrode sheet 120, and a separator 200 located between the positive electrode sheet 110 and the negative electrode sheet 120. A first gel electrolyte 410 is present on both opposing surfaces of the positive electrode sheet 110 and the negative electrode sheet 120. A second gel electrolyte 420 is present in at least a portion of the space between the positive electrode sheet 110 and the negative electrode sheet 120. The second gel electrolyte 420 is located in at least a portion of the space between the opposing surfaces of the first gel electrolyte 410 away from the positive electrode sheet 110 and the negative electrode sheet 120, and the second gel electrolyte 420 is located outside the separator 200. The separator 200 includes separator particles 201 and a fourth gel electrolyte 440 distributed in at least a portion of the pores between the separator particles 201. In this embodiment, at least a portion of the first gel electrolyte 410 is located between the second gel electrolyte 420 and the positive electrode sheet 110, and at least a portion is also located between the second gel electrolyte 420 and the negative electrode sheet 120.

[0175] In one embodiment, a gel electrolyte battery has a gel electrolyte distribution pattern as shown in FIG5 . The gel electrolyte battery includes a positive electrode sheet 110, a negative electrode sheet 120, and a separator 200 positioned between the positive electrode sheet 110 and the negative electrode sheet 120. A first gel electrolyte 410 is disposed on two opposing surfaces of the positive electrode sheet 110 and the negative electrode sheet 120, forming two opposing faces. A second gel electrolyte 420 is disposed in at least a portion of the region between the two opposing faces formed by the first gel electrolyte 410, and the second gel electrolyte 420 is positioned outside the separator 200. The separator 200 includes separator particles 201 and a fourth gel electrolyte 440 distributed in at least a portion of the pores between the separator particles 201.

[0176] In some embodiments, the gel electrolyte battery further comprises a shell, wherein the electrode assembly and the electrolyte are both located inside the shell;

[0177] The electrolyte may also include or exclude a fifth gel electrolyte, and may include or exclude a sixth gel electrolyte, wherein the fifth gel electrolyte is located at least a portion of the outermost surface of the electrode assembly, and the sixth gel electrolyte is located at at least a portion of the relative space between the outermost surface of the electrode assembly and the inner wall of the shell, and the cross-linking degree of the sixth gel electrolyte is higher than that of the fifth gel electrolyte.

[0178] A gel electrolyte can be arranged between the electrode assembly and the battery shell to provide rigid protection for the periphery of the electrode assembly and further improve the overall rigidity of the gel electrolyte battery. The low cross-linking degree of the outermost surface of the electrode assembly combined with the high cross-linking degree between the electrode assembly and the shell can form the first gel electrolyte and the second gel electrolyte at the same time.

[0179] In one embodiment, the gel electrolyte battery has a distribution of the gel electrolyte shown in FIG6 . FIG6 is a longitudinal cross-sectional view (left side) and a partial enlarged view of the longitudinal cross-section (right side) of the gel electrolyte battery in this example. The four areas separated by vertical solid lines in the longitudinal cross-sectional view on the left side represent two bare battery cells assembled by a winding structure. The two bare battery cells are connected in parallel to the top cover through the adapter plate on the top; the partial enlarged view of the longitudinal cross-section on the right side illustrates the stacking of the positive and negative electrode sheets and the separators in the bare battery cells, and shows in detail the distribution of the gel electrolyte in the shell 51. The gel electrolyte battery 5 includes a shell 51 and an electrode assembly. The electrode assembly includes a plurality of positive electrode sheets 110, a plurality of negative electrode sheets 120, and a plurality of separators 200 arranged between any group of relative positive electrode sheets 110 and negative electrode sheets 120, at least one group of relative positive electrode sheets 110 and negative electrode sheets. A first gel electrolyte 410 is present on both opposing surfaces of the electrode assembly 120, a second gel electrolyte 420 is present in at least a portion of the relative space between the aforementioned set of opposing positive electrode sheets 110 and negative electrode sheets 120, the second gel electrolyte 420 is located in at least a portion of the relative space between the two opposing surfaces of the first gel electrolyte 410 away from the positive electrode sheet 110 and away from the negative electrode sheet 120, and the second gel electrolyte 420 is located outside the corresponding isolation membrane 200 and between the two opposing surfaces of the first gel electrolyte 410; a fifth gel electrolyte 450 is present on the outermost surface of the electrode assembly, and a sixth gel electrolyte 460 is present in the area between the electrode assembly and the shell 51; the sixth gel electrolyte is located in the area where the fifth gel electrolyte 450 is away from the electrode assembly.

[0180] In some embodiments, the ratio of the sum of the mass m5 of the gel portion of the fifth gel electrolyte and the mass m6 of the gel portion of the sixth gel electrolyte to the sum of the mass m1 of the gel portion of the first gel electrolyte and the mass m2 of the gel portion of the second gel electrolyte satisfies 0≤(m5+m6) / (m1+m2)≤12.5%, optionally satisfies 0≤(m5+m6) / (m1+m2)≤10%, further optionally satisfies 4%≤(m5+m6) / (m1+m2)≤12.5%, further optionally satisfies 5%≤(m5+m6) / (m1+m2)≤12.5%, and further optionally satisfies 5%≤(m5+m6) / (m1+m2)≤10%. (m5+m6) / (m1+m2) can also be any of the following percentages, or an interval selected from any two of the following percentages: 0, 0.1%, 0.2%, 0.25%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.75%, 0.8%, 0.9%, 1%, 1.2%, 1.25%, 1.3%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 9%, 10%, 11%, 12%, 12.5%, etc.

[0181] By controlling the ratio of the gel electrolyte outside the electrode assembly (including the fifth gel electrolyte on the outermost surface of the electrode assembly and the sixth gel electrolyte between the electrode assembly and the shell, corresponding to m5+m6) to the gel electrolyte outside the electrode plate in the electrode assembly area (including the first gel electrolyte on the surface of the electrode plate and the second gel electrolyte in at least a part of the relative space between the electrode plates, corresponding to m1+m2), the gel electrolyte outside the electrode assembly can be controlled within a certain range, which can not only provide a certain rigid protection for the periphery of the electrode assembly, but also provide sufficient gel electrolyte in the area where the electrode assembly is located, maintaining good battery capacity performance while providing higher battery rigidity, and can also play a role in effectively transmitting active ions during the charge and discharge cycle of the battery.

[0182] In some embodiments, the electrolyte further comprises or does not comprise a liquid electrolyte;

[0183] Optionally, the mass ratio of the gel portion of the gel electrolyte to the liquid electrolyte is 1:(0-0.05), further optionally 1:(0.01-0.05), and further optionally 1:(0.02-0.04). Non-limiting examples of the mass ratio of the gel portion of the gel electrolyte to the liquid electrolyte include 1:0.02, 1:0.03, 1:0.04, 1:0.05, etc.

[0184] While introducing gel electrolyte into gel electrolyte batteries, traditional liquid electrolyte can also be retained, which can significantly improve the overall stiffness of the battery. At this time, the interface wetting contact between the active material and the gel electrolyte can be improved, and the electrolyte consumption during the cycle can be replenished, thereby improving the long-term cycle performance of the battery.

[0185] In some embodiments, the positive electrode sheet includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a lithium ion material. When the active ions in the gel electrolyte battery include lithium ions, the electrolyte salt in the electrolyte may include a lithium salt that is more compatible with the active ions, thereby facilitating better transport of the active lithium ions.

[0186] In some embodiments, the electrolyte salt in the electrolyte includes a lithium salt. In this case, the ions that can be ionized from the electrolyte salt include lithium ions, which is more conducive to conducting active lithium ions.

[0187] In some embodiments, the electrolyte salt in the gel electrolyte comprises a lithium salt. In some examples thereof, the electrolyte salt in the first gel electrolyte and the second gel electrolyte each independently comprises a lithium salt.

[0188] In some embodiments, the electrolyte salt in the gel electrolyte is a lithium salt. In some embodiments, the electrolyte salt in the first gel electrolyte and the second gel electrolyte are each independently a lithium salt.

[0189] In some embodiments, the electrolyte salt in the liquid electrolyte comprises a lithium salt. In some embodiments, the electrolyte salt in the liquid electrolyte is a lithium salt.

[0190] In some embodiments, the electrolyte salt in the gel electrolyte and the electrolyte salt in the liquid electrolyte each independently comprises a lithium salt. In some embodiments, the electrolyte salt in the gel electrolyte and the electrolyte salt in the liquid electrolyte each independently comprises a lithium salt.

[0191] The lithium salt in the electrolyte salt may be distributed in at least one of the gel electrolyte and the liquid electrolyte, may be distributed in at least the gel electrolyte, and may also be distributed in at least the liquid electrolyte. Without limitation, the lithium salt in the electrolyte salt may be distributed in both the gel electrolyte and the liquid electrolyte.

[0192] In some embodiments, the electrolyte salt in the liquid electrolyte is a lithium salt.

[0193] In some embodiments, the electrolyte salts in the gel electrolyte and the liquid electrolyte are both lithium salts.

[0194] In some embodiments, the gel electrolyte battery is a lithium-ion secondary battery. Further, the electrolyte salt therein may include a lithium salt. In some preferred examples, the electrolyte salt therein is a lithium salt.

[0195] When the active ions in a gel electrolyte battery include lithium ions, the electrolyte salts in the gel electrolyte and the liquid electrolyte can each independently contain a lithium salt to better perform the function of transporting the active ions. Furthermore, the electrolyte salts in the first gel electrolyte and the second gel electrolyte can each independently contain a lithium salt, which is conducive to better performing the function of transporting the active ions.

[0196] In one embodiment of the present application, the gel electrolyte battery includes a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the battery's charge and discharge processes, active ions are intercalated and released back and forth between the positive and negative electrode sheets. The electrolyte conducts the active ions between the positive and negative electrode sheets.

[0197] In one embodiment of the present application, the gel electrolyte battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are intercalated and released between the positive and negative electrode sheets. The electrolyte conducts the active ions between the positive and negative electrode sheets. The separator is disposed between the positive and negative electrode sheets, primarily preventing a short circuit between the positive and negative electrodes while allowing the active ions to pass through.

[0198] The types of active ions can be as described above.

[0199] electrolytes

[0200] The electrolyte conducts ions between the positive and negative electrodes.

[0201] The electrolyte in the gel electrolyte battery provided in this application includes at least the aforementioned gel electrolyte and may also include the aforementioned liquid electrolyte. In terms of physical form, the electrolyte includes at least a gel state and may also include a liquid state. In this application, the gel electrolyte is referred to as a gel electrolyte, and the liquid electrolyte is referred to as a liquid electrolyte or electrolyte.

[0202] In the present application, unless otherwise specified, at least a portion of the gel electrolyte is distributed in at least a portion of the surface of at least one side of at least one electrode plate (corresponding to the first gel electrolyte), and at least a portion of the gel electrolyte is distributed in at least a portion of the relative space between at least one set of oppositely disposed positive and negative electrode plates (corresponding to the second gel electrolyte), and the degree of cross-linking of the gel portion of the second gel electrolyte is higher than the degree of cross-linking of the gel portion of the first gel electrolyte.

[0203] The definitions of electrolyte, gel electrolyte and liquid electrolyte may also refer to other descriptions in the context.

[0204] The gel skeleton in the condensed electrolyte can be formed by a polymerization reaction of a cross-linkable monomer, wherein a corresponding initiator and / or a cross-linking agent can be added during the polymerization reaction.

[0205] The reaction in which a crosslinkable monomer forms the gel backbone is generally a polymerization reaction. Here, the crosslinkable monomer is a polymerizable monomer. Monomers that participate in the formation of the gel backbone through polymerization are collectively referred to as polymerizable monomers. Polymeric monomers include at least, but are not limited to, crosslinkable monomers. For example, polymerizable monomers may also include chain-extending monomers. Chain-extending monomers can provide linear segments between the crosslinking points of the gel backbone.

[0206] In the present application, the cross-linkable monomer includes a functional group pair that can undergo a cross-linking reaction. Non-limiting examples of functional group pairs that can undergo a cross-linking reaction include multiple carbon-carbon double bonds, and further examples include monomers containing at least 2 carbon-carbon double bonds; such as a cross-linking monomer combination, and further examples include a cross-linking monomer combination including two monomers, one monomer including at least 2 reactive groups F1, and the other monomer including at least 3 reactive groups F2, and F1 and F2 can be coupled to form a covalent bond. Non-limiting examples of carbon-carbon double bonds include CH2=CH-CH2-, CH2=C(CH3)-CH2-, etc. The hydrogen atoms on the carbon-carbon double bonds can be replaced by suitable substituents, as long as they do not affect the cross-linking polymerization reaction. Non-limiting examples of cross-linking monomer combinations include a combination of a polyol or polyamine with a polyisocyanate, which can undergo a coupling reaction between -OH or an amino group (such as -NH2 or >NH) and -NCO to form a polyurethane or polyurea; and a combination of a polyacid and a polyamine, which can undergo a coupling reaction between -COOH and -NH2 or >NH to form a polymer containing an amide bond (-CO-NH- or -CO-N<), etc.

[0207] The types of polymerizable monomers may include, but are not limited to, one or more of carbonate monomers, sulfone monomers, isocyanate monomers, amide monomers, nitrile monomers, fluorinated monomers, ether compound monomers, ether segment-containing oligomers, and siloxanes.

[0208] When performing the crosslinking reaction of the crosslinkable monomer, the system may or may not contain an initiator, depending on the needs of the crosslinking reaction. When adding an initiator, the initiator may include, but is not limited to, one or more of azo initiators (such as azobisisobutyronitrile (AIBN)), peroxide initiators, anionic and cationic initiators, organometallic compound initiators, amine catalyst initiators, and organophosphorus initiators. The type and amount of the initiator can be appropriately selected and controlled based on the type and amount of the polymerizable monomers (including at least the crosslinkable monomers). For example, the mass ratio of the initiator to the crosslinkable monomers can be 1% to 5%, but is not limited thereto.

[0209] In some embodiments, the electrolyte in the gel electrolyte battery is a non-aqueous electrolyte. The non-aqueous electrolyte includes an electrolyte salt and a solvent. In the present application, the composition of the gel electrolytes at different positions (such as at least two of the first gel electrolyte, the second gel electrolyte, the third gel electrolyte, the fourth gel electrolyte, the fifth gel electrolyte and the sixth gel electrolyte) may be the same or different. The electrolyte salts in the gel electrolytes at different positions may be the same or different. The electrolyte salts in the first gel electrolyte, the second gel electrolyte, the third gel electrolyte, the fourth gel electrolyte, the fifth gel electrolyte and the sixth gel electrolyte may be independent of each other, and any two of them may be the same or different. The solvents in the gel electrolytes at different positions may be the same or different. The solvents in the first gel electrolyte, the second gel electrolyte, the third gel electrolyte, the fourth gel electrolyte, the fifth gel electrolyte and the sixth gel electrolyte may be independent of each other, and any two of them may be the same or different.

[0210] In some embodiments, the gel electrolyte battery is a lithium ion secondary battery, and the electrolyte salt may include an electrolyte lithium salt. In some embodiments, the electrolyte salt contained in one or more of the first gel electrolyte, the second gel electrolyte, the third gel electrolyte, the fourth gel electrolyte, the fifth gel electrolyte, and the sixth gel electrolyte includes a lithium salt.

[0211] In some embodiments, the electrolyte lithium salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).

[0212] In some embodiments, the solvent in the electrolyte is a non-aqueous solvent, and further may be an organic solvent, and further may include but is not limited to one or more of a carboxylate solvent, a carbonate solvent, and a sulfone solvent. The carboxylate solvent may be a carboxylate or a halogenated carboxylate thereof, and further may be C 2-4 C of alkyl carboxylic acid 1-3 Alkyl ester or its halide. Halide of carboxylic acid ester is also called halocarboxylic acid ester. 1-4 Examples of alkyl carboxylic acids include acetic acid, propionic acid, and butyric acid. 1-3 Examples of alkyl esters include methyl ester, ethyl ester, and propyl ester. Carbonate solvents can be carbonates or their halides. Carbonate halides are also called halogenated carbonates. The halogen substituents in halogenated carboxylates and halogenated carbonates can be fluorine, and the number of halogen substituents can range from 1 to perhalogenated. Taking fluorinated as an example, the number of fluorine atoms in fluorinated carboxylates and fluorinated carbonates can range from 1 to perfluorinated.

[0213] Without limitation, the solvent in the electrolyte may include but is not limited to fluoroethylene carbonate, ethylene carbonate (or ethylene carbonate, ), propylene carbonate (or propylene carbonate, ), one or more of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. In some embodiments, the solvent in the electrolyte of the gel electrolyte battery includes fluoroethylene carbonate. In some embodiments, the solvent in the electrolyte of the gel electrolyte battery is fluoroethylene carbonate.

[0214] In some embodiments, the solvent in the electrolyte can be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0215] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0216] The first, second, third, fourth, fifth, and sixth gel electrolytes may each independently include or exclude additives. When at least two of the first, second, third, fourth, fifth, and sixth gel electrolytes include additives, the types of the additives in the two gel electrolytes may be the same or different.

[0217] In some embodiments, the additives in the electrolyte may include, but are not limited to, vinylene carbonate (VC, ), vinyl ethylene carbonate (VEC, ), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), methylene methanedisulfonate (MMDS), 1-propylene-1,3-sultone (PST), ethylene sulfite (ES), propylene sulfite (PS), diethylene sulfate (DTD), succinonitrile (SN), adiponitrile (AND), sulfonate cyclic quaternary ammonium salt, tris(trimethylsilyl) phosphate (TMSP), tris(trimethylsilyl) borate (TMSB) and anisole.

[0218] Negative electrode

[0219] The negative electrode sheet in the gel electrolyte battery provided in the present application includes a negative electrode active material layer, and the negative electrode active material layer includes a negative electrode active material.

[0220] The negative electrode active material may include negative electrode active materials for batteries that are well known in the art. As non-limiting examples, other negative electrode active materials may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may include one or more of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone, or two or more may be used in combination.

[0221] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material layer, and the negative electrode active material layer includes a negative electrode active material. The negative electrode active material can be as defined above.

[0222] As a non-limiting example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0223] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0224] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include styrene-butadiene rubber.

[0225] (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol

[0226] One or more of polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS). An example of a PAA-based binder is polyacrylic acid (PAA).

[0227] In some embodiments, the binder in the negative electrode film layer or the negative electrode active material layer includes one or more of PAA and SBR.

[0228] In some embodiments, the negative electrode film layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0229] In some embodiments, the negative electrode active material layer may further include other auxiliary agents, such as a thickener, etc. Non-limiting examples of thickeners may include sodium carboxymethyl cellulose (CMC-Na), etc.

[0230] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode current collector, and after drying, compacting (compacting can be performed by cold pressing), etc., the negative electrode sheet can be obtained. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or two surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 30wt% to 70wt%. The viscosity of the negative electrode slurry at room temperature can be 2000mPa·s to 10000mPa·s. When coating the negative electrode slurry, the unit surface density of the coating can be 35g / m2 on a dry weight basis. 2 ~150g / m 2 The compaction density of the negative electrode can be 1.0g / cm 3 ~1.8g / cm 3 .

[0231] Positive electrode

[0232] In the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material layer. Further, the positive electrode active material layer includes a positive electrode active substance.

[0233] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0234] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material on a polymer material substrate; the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy; non-limiting examples of polymer material substrates include substrates made of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), and the like.

[0235] In some embodiments of the present application, the positive electrode active material includes a lithium ion material; further, the gel electrolyte battery is a lithium ion secondary battery.

[0236] In some embodiments of the present application, the gel electrolyte battery is a lithium-ion secondary battery. A lithium-ion secondary battery utilizes the intercalation and deintercalation of lithium ions in electrodes and their transport through the electrolyte to achieve charge and discharge. Generally speaking, the active ions in a lithium-ion secondary battery are lithium ions, but this is not limited to these.

[0237] The positive electrode active material may be a positive electrode active material for batteries that is well known in the art. As a non-limiting example, the positive electrode active material or lithium ion material may include one or more of the following materials or substances: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials or substances, and other traditional materials or substances that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, non-limiting examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Non-limiting examples of lithium cobalt oxide include LiCoO2; non-limiting examples of lithium nickel oxide include LiNiO2; non-limiting examples of lithium manganese oxide include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxide include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide include LiNi 0.85 Co 0.15 Al 0.05O2. Non-limiting examples of olivine-structured lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Non-limiting examples of lithium iron phosphate include LiFePO4 (also referred to as LFP); non-limiting examples of lithium manganese phosphate include LiMnPO4.

[0238] In some embodiments, the positive electrode active material layer may further optionally include a binder. As non-limiting examples, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0239] In some embodiments, the positive electrode active material layer may further include a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0240] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent to form a positive electrode slurry; the positive electrode slurry is coated on at least one side of the positive electrode current collector, and after drying, compacting (compaction can be performed by cold pressing) and other processes, the positive electrode sheet can be obtained. The type of solvent can be selected from but not limited to any one of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector or on both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40wt% to 80wt%. The viscosity of the positive electrode slurry at room temperature can be 5000mPa·s to 25000mPa·s. When applying the positive electrode slurry, the unit area density of the coating can be 130g / m2 on a dry weight basis. 2 ~400g / m 2 The compaction density of the positive electrode sheet can be 3.0 to 3.6 g / cm 3 , can be selected as 3.3~3.5g / cm 3 .

[0241] Isolation film

[0242] In some embodiments, the gel electrolyte battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0243] In some embodiments, the material of the separator may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0244] Electrode assembly, electrochemical energy storage device, gel electrolyte battery (a secondary battery)

[0245] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0246] In some embodiments, the electrochemical energy storage device may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0247] In some embodiments, the gel electrolyte battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0248] In some embodiments, the outer packaging of the gel electrolyte battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the gel electrolyte battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic. Non-limiting examples of the plastic include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0249] The present application has no particular limitation on the shape of the gel electrolyte battery, which can be cylindrical, square, or any other shape. For example, FIG7 shows a square gel electrolyte battery 5 as an example.

[0250] The gel electrolyte battery provided in this application can enhance the rigidity of the bare cell itself, improve the cell's ability to resist deformation and safety, and is particularly effective when used in soft-pack cells.

[0251] In some embodiments, referring to Figure 8, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The distribution of the electrolyte relative to the electrode assembly or a part thereof is as described above. The number of electrode assemblies 52 contained in the gel electrolyte battery 5 can be one or more, and those skilled in the art can select according to actual needs.

[0252] In a second aspect, the present application provides a method for preparing a gel electrolyte battery, which comprises the following steps:

[0253] The electrode assembly is installed in the housing, wherein the electrode assembly includes a positive electrode sheet, a separator and a negative electrode sheet, and the separator is arranged between the positive electrode sheet and the negative electrode sheet;

[0254] Injecting a first injection material into the housing, wherein the first injection material includes a first electrolyte salt, a first polymerizable monomer, and a first solvent;

[0255] Carry out chemical formation;

[0256] curing the first injection material to form a first gel electrolyte on at least a portion of the surface of the positive electrode sheet and the negative electrode sheet;

[0257] injecting a second liquid injection material into the housing, wherein the second liquid injection material includes a second electrolyte salt, a second polymerizable monomer, and a second solvent;

[0258] The second injection material is subjected to a curing reaction to form a second gel electrolyte in at least a portion of the relative space between the positive electrode plate and the negative electrode plate; wherein the crosslinking degree of the gel portion of the second gel electrolyte is higher than the crosslinking degree of the gel portion of the first gel electrolyte.

[0259] In this application, unless otherwise specified, "polymerization monomer" refers to a cross-linkable monomer that can form a gel skeleton in a gel electrolyte through a curing reaction. Depending on the needs of the polymerization reaction, an initiator, a cross-linking agent, or a chain extender may or may not be added to the injection material containing the first polymerization monomer or the second polymerization monomer. The chain extender may be a chain-extending monomer. In this application, "performing a curing reaction" is equivalent to describing the selection of whether to add an initiator, a cross-linking agent, or a chain extender, and the type and amount of the initiator and cross-linking agent can be appropriately selected.

[0260] In the context of this application, the terms "first" and "second" in "first electrolyte salt", "second electrolyte salt", "first polymerized monomer", "second polymerized monomer", "first solvent" and "second solvent" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features.

[0261] By adding polymerizable monomers to the electrolyte raw material, a gel electrolyte can be formed through a curing reaction. The liquid raw material of the electrolyte is further injected and cured in steps. After the first injection, the first gel electrolyte is formed on the surface of the electrode plate after formation and the first curing. Then, the second injection and curing are performed to form a second gel electrolyte in at least a part of the relative space between the electrode plates (or the second gel electrolyte is formed on the side of the first gel electrolyte away from the surface of the electrode plate). By controlling the cross-linking degree of the gel electrolyte formed in different curing steps, the gel electrolyte can be formed in a gradient and coordinated cross-linking degree at different positions of the battery. By controlling the second gel electrolyte The cross-linking degree of the gel part of the gel electrolyte is higher than the cross-linking degree of the gel part of the first gel electrolyte, and the gel electrolyte battery of the first aspect of the present application can be prepared, wherein the gel electrolyte can have a synergistic distribution of low cross-linking on the surface of the electrode plate and high cross-linking in the relative space of the electrode plate. On the one hand, the surface of the electrode plate with low cross-linking degree can absorb and swell more liquid electrolyte, thereby having better infiltration in the pores and surface of the electrode plate, which is more conducive to the performance of electrical properties such as capacity. On the other hand, the design of high cross-linking degree in the relative space of the electrode plate can give the battery higher rigidity, further enhance the ability of the battery to resist deformation during use, thereby significantly improving the safety performance of the battery cell.

[0262] The first polymerized monomer and the second polymerized monomer can each independently be selected from one or more of the crosslinkable monomers defined above and below. The first polymerized monomer and the second polymerized monomer can also each independently include or include a chain extender monomer. When a chain extender monomer is included, it can include one or more of the chain extender monomers described above and below.

[0263] In some embodiments, the cross-linkable monomer contains at least two carbon-carbon double bonds.

[0264] In the present application, unless otherwise specified, a "carbon-carbon double bond" refers to a C=C structure capable of undergoing an addition reaction to form a -CC- structure.

[0265] Without limitation, the crosslinkable monomer may include one or more of ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,4-butanediol diacrylate, glycerol dimethacrylate, 1,2-propylene glycol dimethyl acrylate, 1,3-butanediol dimethacrylate, dipropylene glycol diacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, glycerol trimethacrylate, pentaerythritol tetramethacrylate, cyclohexanetriol trimethacrylate, divinylbenzene, ethylene glycol diallyl ether, polyethylene glycol diallyl ether, and pentaerythritol triallyl ether, and may also include one or more halogenated compounds of the foregoing compounds. The number of halogen atoms substituted in the halogenated compound may be one or more. In one embodiment, all hydrogen atoms on the carbon-carbon double bond are replaced by halogen atoms, such as fluorine atoms. The polyethylene glycol dimethacrylate may include one or more of diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate, but is not limited thereto. The polyethylene glycol portion of the polyethylene glycol diallyl ether may be 2, 3, or 4 ethylene glycol units, but is not limited thereto. The aforementioned carboxylate molecule may be methyl, ethyl, propyl, or butyl, but is not limited thereto. As a non-limiting example, diethylene glycol methyl dimethacrylate is exemplified. Without limitation, the chain-extending monomer may be an unsaturated monoolefin molecule, including but not limited to one or more of vinylidene fluoride, hexafluoropropylene, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, n-butyl methacrylate, butyl acrylate, n-octyl methacrylate, n-octyl acrylate, allyl methacrylate, styrene, α-methylstyrene, acrylonitrile, acrylic acid, methacrylic acid, butyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, etc., and may also be a halogenated compound (such as a fluorinated compound) of the aforementioned suitable compound.

[0266] In some embodiments, the mass concentration of the first polymerizable monomer in the first injection material is recorded as c1, and the mass concentration of the second polymerizable monomer in the second injection material is recorded as c2, wherein c1 <c2。

[0267] In some embodiments, the mass concentration of the first polymerization monomer in the first injection material is 2% to 6%, and can further be 3% to 5%, with non-limiting examples such as 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, etc.

[0268] In some embodiments, the mass concentration of the second polymerization monomer in the second injection material is 5% to 10%, and can further be 8% to 10%, with non-limiting examples such as 5%, 5.5%, 6%, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10%, etc.

[0269] In the present application, the mass concentration expressed as a percentage, unless otherwise specified, corresponds to % (w / w).

[0270] In some embodiments, the mass ratio of the first injection material to the second injection material is (1-9):1.

[0271] In some embodiments, the mass ratio of the first injection material to the second injection material is (2-6):1.

[0272] The mass ratio of the first injection material to the second injection material can also be any of the following proportions or ratios, and can also be selected from the interval consisting of any two of the following proportions or ratios: 1:1, 1.25:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, :1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, etc.

[0273] The coordinated design of low cross-linking on the surface of the electrode plates and high cross-linking in the relative space of the electrode plates in the obtained gel electrolyte battery, or the design of sequentially setting low cross-linking areas and high cross-linking areas on the surface of the electrode plates, can be achieved by controlling the polymerization monomer concentration (such as mass concentration c2) in the injection material during the second injection to be higher than the polymerization monomer concentration (such as mass concentration c1) in the injection material during the first injection. Furthermore, the polymerization monomer concentration during the two injections can be adjusted to a more appropriate range, and the mass ratio of the two injections can also be adjusted, so as to better control the gel electrolyte in the battery to have a more appropriate gradient distribution and better balance the comprehensive performance of battery capacity and battery stiffness improvement.

[0274] In some embodiments, the gel electrolyte battery prepared by the preparation method is as defined in the first aspect of the present application.

[0275] In a third aspect, the present application provides an electrical device comprising at least one of the gel electrolyte battery described in the first aspect of the present application and the gel electrolyte battery prepared by the preparation method described in the second aspect of the present application.

[0276] The gel electrolyte battery can be used as a power source or energy storage unit for the electrical devices. These devices may include, but are not limited to, mobile devices, electric vehicles, electric trains, ships, satellites, and energy storage systems. Examples of mobile devices include, but are not limited to, mobile phones and laptops; and examples of electric vehicles include, but are not limited to, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, and electric trucks.

[0277] As the electrical device, a gel electrolyte battery can be selected according to its usage requirements.

[0278] FIG9 shows an example of an electric device 6. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or battery module may be used.

[0279] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be lightweight and thin, and may use a gel electrolyte battery as a power source.

[0280] Below, some embodiments of the present application are described. The embodiment described below is exemplary, is only used to explain the present application, and cannot be construed as limiting the present application. In the embodiment, if no technology or conditions are indicated, it is carried out according to the description above, or according to the technology or conditions described in the document in this area or according to the product specification. Reagents used or instruments that are not indicated by the manufacturer are conventional products that can be obtained commercially, or can be synthesized in a conventional manner by commercially available products.

[0281] In the following examples, room temperature refers to 20° C. to 30° C., and further, may be 25° C. Ethylene glycol dimethacrylate is ethylene glycol ethyl dimethacrylate.

[0282] Example 1.

[0283] (1) Positive electrode

[0284] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (i.e. NCM811), conductive agent acetylene black and polyvinylidene fluoride (PVDF) were mixed in a solvent N-methylpyrrolidone (NMP) at a weight ratio of 97:1:2 and then coated on both sides of the aluminum foil. The foil was dried and cold pressed to obtain the positive electrode sheet. When the positive electrode slurry was applied, the coating unit area density was 0.018g / cm2 based on dry weight (excluding solvent). 2 (i.e. 18 mg / cm 2), the compaction density of the positive electrode is 3.5g / cm 3 .

[0285] (2) Negative electrode

[0286] The negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were mixed in deionized water at a weight ratio of 97:1:1:1. The mixture was then applied to both sides of the copper foil, dried, and cold pressed to obtain the negative electrode sheet. When applying the negative electrode slurry, the coating unit area density (excluding solvent) was 0.012 g / cm 2 (i.e. 12 mg / cm 2 ), the compaction density of the negative electrode is 1.7g / cm 3 .

[0287] (3) Electrolytes

[0288] Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and then lithium hexafluorophosphate (LiPF6) was uniformly dissolved in the above mixture to obtain an electrolyte base solution, wherein the concentration of LiPF6 was 1 mol / L and the density of the electrolyte base solution was about 1.2 g / cm 3 .

[0289] The electrolyte base liquid is divided into two parts, mixed with the polymerization monomer and initiator in a certain proportion respectively, and shaken to prepare two electrolyte mother solutions.

[0290] The first injection liquid material is prepared by fully mixing electrolyte base liquid: monomer (ethylene glycol dimethacrylate): initiator (azobis(ethyl butyronitrile) AIBN) in a weight ratio of 95.5%:4%:0.5% and then setting aside.

[0291] The second injection material is prepared by fully mixing electrolyte base liquid: monomer (ethylene glycol dimethacrylate): initiator (azobis(ethyl butyronitrile) AIBN) in a ratio of 91%:8%:1% and then setting aside.

[0292] In this example,

[0293] The first polymerizable monomer is ethylene glycol dimethacrylate, and the mass concentration c1 of the first polymerizable monomer in the first injection material is 4%. The second polymerizable monomer is ethylene glycol dimethacrylate, and the mass concentration c2 of the second polymerizable monomer in the second injection material is 8%.

[0294] The first electrolyte salt and the second electrolyte salt are both lithium salt lithium hexafluorophosphate. The concentration c1 of the first electrolyte salt (which can be recorded as the first lithium salt) in the first injection material is 1 mol / L, and the concentration c2 of the second electrolyte salt (which can be recorded as the second lithium salt) in the second injection material is 0.9 mol / L.

[0295] The first solvent and the second solvent are both a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 1:1:1.

[0296] (3) Isolation film

[0297] The isolation membrane adopts a universal membrane purchased from Cellgard, model number is Cellgard 2400.

[0298] (4) Preparation of gel electrolyte batteries

[0299] Assemble the positive electrode sheet, the negative electrode sheet, and the separator into an electrode assembly in a conventional winding manner, and add the electrode assembly into a shell to obtain a square shell battery;

[0300] Then, the first liquid injection material is injected, and after being fully soaked, it is left to stand at 80°C for 12 hours to crosslink and solidify, at which time, a low-crosslinked first gel electrolyte is formed on at least part of the surface of the electrode;

[0301] Then inject the second liquid material, and after sufficient infiltration, place it at 80°C for 12 hours to crosslink and solidify it, forming a second gel electrolyte with a high degree of crosslinking in at least a part of the relative space between the positive electrode sheet and the negative electrode sheet.

[0302] The volumes of the first injection material and the second injection material are 80% and 20% of the preset total injection volume, respectively. The preset total injection volume is determined based on a preset injection coefficient. The injection coefficient has a conventional meaning in the art and is calculated as: injection volume divided by preset capacity, and the unit may be g / Ah.

[0303] The weight ratio of the first injection material to the second injection material is 4:1, so as to control the weight ratio of the first gel electrolyte to the second gel electrolyte.

[0304] The "mass ratio of the gel portion of the gel electrolyte to the liquid electrolyte in the battery" in Table 1 is controlled as follows: the mass ratio of the two is regulated by changing the ratio of the gel portion (or monomer + initiator) and the "solvent + electrolyte salt" base liquid. However, the cross-linking degree of the gel portion is relatively high, and an increase in the ratio of the base liquid will increase the mass of the liquid electrolyte.

[0305] It should be noted that, while the first gel electrolyte is being formed, a third gel electrolyte can also form within the pores of the electrode sheet, a fourth gel electrolyte can also form within the separator, and a fifth gel electrolyte can also form on the outermost surface of the electrode assembly. The formation of the third gel electrolyte is related to the infiltration of the first injection material into the electrode sheet. The formation of the fourth gel electrolyte is related to the infiltration of the first injection material into the separator. The formation of the fifth gel electrolyte is related to the formation conditions of the first gel electrolyte.

[0306] While forming the second gel electrolyte, a sixth gel electrolyte may also be formed between the electrode assembly and the housing. The formation of the sixth gel electrolyte is related to the formation conditions of the second gel electrolyte.

[0307] In the embodiments of the present application (including this example), the amount of liquid electrolyte is determined by the residual amount after the polymerized monomer undergoes a curing reaction. In the present application, the liquid electrolyte may not exist. When the proportion of additives in the electrolyte base liquid is high, residual liquid electrolyte is likely to appear. In addition, the amount of the third gel electrolyte, the fourth gel electrolyte, the fifth gel electrolyte, and the sixth gel electrolyte can also be passively determined based on the distribution and infiltration degree of the electrolyte base liquid and the degree of progress of the curing reaction.

[0308] Examples 1-16 were prepared using methods substantially identical to those of Example 1, with the differences being the parameters shown in Tables 1 and 2. The total mass of the first and second injection materials was maintained constant, and the mass ratio of the first and second injection materials was within a range of (1-9):1, and further within a range of (2-6):1.

[0309] Comparative Example 1 employed a preparation method substantially identical to that of Example 1, except that a single electrolyte was used, the total mass injected was the same as the total mass of the first and second injection materials in Example 1, and the two curing steps were omitted. The electrolyte composition was the electrolyte base solution of Example 1.

[0310] Comparative Example 2 employed a preparation method substantially identical to that of Example 1, except that the second injection step was omitted. In other words, a single injection material was used. The composition and mass of the single injection material were identical to those of the first injection material in Example 1, and only one curing step was performed. Furthermore, the curing parameters were the same as those in Example 1.

[0311] Comparative Example 3 employed a preparation method substantially identical to that of Example 1, except that the second injection step was omitted. In other words, a single injection material was used. The composition of the single injection material was identical to that of the first injection material in Example 1, and the mass of the single injection material was identical to the total mass of the first and second injection materials in Example 1. Only one curing step was performed. Furthermore, the curing parameters were the same as those in Example 1.

[0312] Comparative Example 4 employed a preparation method substantially identical to that of Example 1, with the exception that the first injection step was omitted. In other words, a single injection material was used. The composition and mass of the single injection material were identical to those of the second injection material in Example 1, and only one curing step was performed. Furthermore, the curing parameters were the same as those in Example 1.

[0313] Comparative Example 5 employed a preparation method substantially identical to that of Example 1, except that the first injection step was omitted. A single injection material was used, the composition of which was identical to that of the second injection material in Example 1, and the mass of which was identical to the total mass of the first and second injection materials in Example 1. Only one curing step was performed. Curing parameters were otherwise the same as those in Example 1.

[0314] Comparative Example 6 was prepared using a method substantially identical to that of Example 1, except that a single injection material was used (the composition and mass of the single injection material are shown in Table 1), and only one curing step was performed. In addition, the curing parameters were the same as those of Example 1.

[0315] The preparation method of a single injection material is as follows: the electrolyte base liquid of Example 1: monomer (ethylene glycol dimethacrylate): initiator (azobis(ethyl butyronitrile) AIBN) are fully mixed in a weight ratio of 92.25%:6%:0.75% and then set aside.

[0316] Comparative Example 7 adopts the same preparation method as Example 1, except that:

[0317] The first injection uses the second injection material in Example 1, and its volume is the same as that of the first injection material in Example 1, which is 80% of the preset total injection mass.

[0318] The second injection adopts the first injection material in Example 1, and the volume is the same as that of the first injection material in Example 1, which is 20% of the preset total injection mass.

[0319] Table 1.

[0320] Table 2. Second injection material composition and second curing

[0321] Test analysis methods

[0322] 1. Performance analysis of gel electrolytes in different regions

[0323] 1.1. Sampling method of the first gel electrolyte (electrode surface) and the second gel electrolyte (the relative space between the positive and negative electrodes):

[0324] The sample is finely sliced ​​using a cryo-focused ion beam (FIB) (down to nanoscale slices) to separate the first and second gel electrolyte samples. Scanning electron microscopy (SEM) is also used to analyze the morphology, structure, and elemental distribution of each cross-section layer under FIB continuous sectioning. Combined with 3D structure reconstruction software, the 3D structure of the sample can be reconstructed to estimate mass and / or volume. Elemental analysis methods include energy dispersive spectroscopy (EDS) combined with elemental spectroscopy.

[0325] 1.2. Cross-linking degree analysis

[0326] For cross-linking test, please refer to GB / T 18474-2001 Test method for cross-linking degree of cross-linked polyethylene (PE-X) pipes and fittings.

[0327] Sample preparation method: obtain a gel electrolyte sample from a designated location of a gel electrolyte battery, perform freeze drying, remove electrolyte salts, solvents and other optional components as well as liquid electrolyte in the gel electrolyte through washing and solid-liquid separation operations, and collect the remaining gel skeleton to obtain a gel sample of the "gel portion of the gel electrolyte".

[0328] Test method: Refer to GB / T 18474-2001 for crosslinking test. First, weigh the initial mesh bag (W1). Add the sample to the mesh bag and seal it to make a sample bag. Weigh the total weight (W2). Then, add xylene solvent to a flask, immerse the sample bag in the solvent, and heat and extract it. The solvent evaporates, carrying with it uncrosslinked monomers or oligomers, leaving behind a crosslinked residual polymer sample. After drying, weigh the total weight (W3) of the crosslinked polymer sample and mesh bag.

[0329] The calculation formula is: cross-linking degree = (W3-W1) / (W2-W1)×100%; where W1 is the initial mesh bag weight, W2 is the total weight of the sample and mesh bag before extraction, and W3 is the total weight of the sample and mesh bag after extraction and drying.

[0330] 1.3. Swelling rate analysis, gravimetric test

[0331] Sample preparation method: Same as part 1.2.

[0332] The swelling ratio was obtained by the following gravimetric method: the dried gel sample was weighed (the dry weight of the polymer was obtained as W d ), then soak the sample in the electrolyte at room temperature for at least 24 hours until swelling equilibrium is reached. Samples can be taken at different time points according to multiple parallel samples. After swelling, the weight of the sample is basically no longer changed. The sample is taken out from the electrolyte, the electrolyte on the surface is removed with filter paper, and then weighed to obtain the weight of the sample after swelling equilibrium W S .

[0333] The swelling ratio Q of the sample to be tested is calculated by the following formula: Q = W S / W d , where W S is the weight of the sample after swelling equilibrium, W d is the dry weight of the sample.

[0334] 1.4. Thermal decomposition temperature

[0335] Sample preparation method: Use the same method as in Section 1.2. to obtain gel samples for testing.

[0336] Thermal decomposition temperature analysis: Thermal gravimetric analysis and composition analysis (TG-MS) was used to test the thermal decomposition temperature and composition analysis of different components of the material.

[0337] 2. Stiffness parameters, elastic modulus

[0338] Sample to be tested: battery cell

[0339] Elastic modulus = (F / S) / (ΔH / H)

[0340] F is the force applied to the surface of the soft-pack battery cell, N; S is the force-bearing area of ​​the soft-pack battery cell in m2; ΔH is the thickness change of the soft-pack battery cell under force; H is the initial thickness of the soft-pack battery cell without force.

[0341] The test results can be found in "Elastic Modulus" in Table 6. The larger the elastic modulus, the higher the stiffness.

[0342] 3. Capacity (Ah)

[0343] At 25°C, charge at a constant current rate of 0.5C to 4.25V, then switch to constant voltage charging until the current drops to 0.05C, stop charging, then discharge at a constant current rate of 1C to 2.8V, and record the discharge capacity (Ah).

[0344] The test results can be found in Table 6, “Capacity”.

[0345] 4. Stability analysis of extreme case simulation tests

[0346] Perform a cell extrusion test: fully charge the cell to 100% SOC, with an extrusion speed of ≤2mm / s. Use a 75mm semi-cylinder to extrude the cell perpendicular to its large surface until the extrusion force reaches 100kN, and record the cell extrusion deformation.

[0347] The test results can be found in Table 6, "Simulated Extreme Conditions: Deformation / mm at 100kN Compression." Smaller deformation indicates greater resistance to deformation, greater safety, and lower risk of failure.

[0348] Table 3. Test parameters of the first gel electrolyte and the second gel electrolyte

[0349] In Table 3,

[0350] CX1, Q1 and Td1 are the crosslinking degree, swelling ratio (by weight) and thermal decomposition temperature test values ​​of the gel portion of the first gel electrolyte, respectively;

[0351] CX2, Q21 and Td2 are the crosslinking degree, swelling ratio (by weight) and thermal decomposition temperature test values ​​of the gel portion of the second gel electrolyte, respectively.

[0352] Table 4. Comparison of test results of parameters of the first gel electrolyte and the second gel electrolyte

[0353] In Table 4,

[0354] m 1 / 2 is the mass ratio of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte;

[0355] v 1 / 2 is the volume ratio of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte;

[0356] CX 1 / 2 is the ratio of the crosslinking degree of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte;

[0357] Q 1 / 2 is the swelling ratio of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte, measured by weight method;

[0358] Td 1 / 2 is the ratio of the thermal decomposition temperatures of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte;

[0359] f 1 / 2 is the ratio of the electrolyte salt mass proportion f1 in the first gel electrolyte to the electrolyte salt mass proportion f2 in the second gel electrolyte.

[0360] Table 5.

[0361] In Table 5,

[0362] m 1 / 3 is the weight ratio of the gel portion of the first gel electrolyte to the gel portion of the third gel electrolyte, with significant figures rounded to integers;

[0363] m2 / 4 is the weight ratio of the gel portion of the second gel electrolyte to the gel portion of the fourth gel electrolyte, with significant figures rounded to integers;

[0364] (m5+m6) / (m1+m2) is the ratio of the sum of the mass of the gel portion m5 of the fifth gel electrolyte and the mass of the gel portion m6 of the sixth gel electrolyte to the sum of the mass of the gel portion m1 of the first gel electrolyte and the mass of the gel portion m2 of the second gel electrolyte, with the significant figures being integers.

[0365] Table 6.

[0366] Test results and analysis:

[0367] The test and analysis results of the weight, volume, cross-linking degree, swelling ratio (gravimetric method), thermal decomposition temperature, and composition (lithium salt) of the prepared gel electrolyte battery can be found in Tables 3, 4, and 5.

[0368] According to the test and analysis results, a gel electrolyte battery with the aforementioned special distribution pattern was prepared, in which a gel electrolyte was formed in the battery. The gel electrolyte included a first gel electrolyte located on the surface of the electrode plate and a second gel electrolyte located in the relative space between the positive and negative plates. At least a portion of the first gel electrolyte was located between the second gel electrolyte and the electrode plate, and the degree of cross-linking of the gel portion of the second gel electrolyte was higher than the degree of cross-linking of the gel portion of the first gel electrolyte, forming a coordinated distribution of low cross-linking on the surface of the electrode plate and high cross-linking in the relative space of the electrode plate, or a distribution pattern in which the gel electrolyte formed low cross-linking and high cross-linking in sequence from the surface of the electrode plate.

[0369] The test results of battery capacity, elastic modulus and deformation resistance can be found in Table 6. The gel electrolyte batteries prepared in Examples 1-16 have good electrical properties such as capacity while achieving high stiffness, and have high deformation resistance, low failure risk and good safety.

[0370] Comparative Example 1 does not have a gel electrolyte, Comparative Examples 2-6 only have a gel electrolyte with a single cross-linking degree, and Comparative Example 7 has a lower cross-linking degree of the gel portion of the second gel electrolyte than the gel portion of the first gel electrolyte (that is, the cross-linking degree of the gel electrolyte on the surface of the electrode plate is higher than the relative spatial area of ​​the electrode plate, or low-cross-linked and high-cross-linked gel electrolytes are formed in sequence from the surface of the electrode plate). As a result, both electrical performance and high stiffness cannot be achieved. Among them, the stiffness of Comparative Examples 1-3 and Comparative Example 5 is significantly lower than that of the various embodiments, and the ability to resist deformation is significantly worse than that of the various embodiments. The capacity performance of Comparative Examples 4-5 and 7 is significantly deteriorated. The electrical performance and stiffness performance of Comparative Example 6 are inferior to those of the various embodiments, and the ability to resist deformation is also significantly deteriorated.

[0371] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0372] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and within the scope of the technical solution of the present application, embodiments that have substantially the same structure as the technical idea and exert the same effect are all included in the technical scope of the present application. The above-mentioned embodiments only express several embodiments of the present application, and their descriptions are relatively detailed, but they cannot be understood as limiting the scope of the patent. In addition, without departing from the scope of the subject matter of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of constructing by combining some of the constituent elements in the embodiments are also included in the scope of the present application. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be based on the attached claims, and the description and drawings may be used to explain the content of the claims.

Claims

1. A gel electrolyte battery, comprising an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode sheet and a negative electrode sheet; the electrolyte comprises a gel electrolyte, and the gel electrolyte comprises a first gel electrolyte and a second gel electrolyte; the first gel electrolyte is located in at least a portion of at least one side surface of at least one electrode sheet, and the second gel electrolyte is located on a side of the first gel electrolyte away from the electrode sheet; the electrode sheet is the positive electrode sheet or the negative electrode sheet; The crosslinking degree of the gel portion of the second gel electrolyte is higher than the crosslinking degree of the gel portion of the first gel electrolyte.

2. A gel electrolyte battery, comprising an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode sheet and a negative electrode sheet; the electrolyte comprises a gel electrolyte, and the gel electrolyte comprises a first gel electrolyte and a second gel electrolyte; The first gel electrolyte is located in at least a portion of the first region and the second region: wherein The first region is the surface region of the negative electrode sheet, and the second region is the surface region of the positive electrode sheet; The second gel electrolyte is located in at least a portion of the relative space between the positive electrode sheet and the negative electrode sheet; The crosslinking degree of the gel portion of the second gel electrolyte is higher than the crosslinking degree of the gel portion of the first gel electrolyte.

3. The gel electrolyte battery according to claim 1 or 2, wherein: The mass ratio m of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2 It is (0.2-3):1, can be optionally (0.5-1):1, can be further optionally (0.79-1):1, can be further optionally 1:

1.

4. The gel electrolyte battery according to any one of claims 1 to 3, wherein The volume ratio v of the gel portion of the first gel electrolyte to the gel portion of the second gel electrolyte is 1 / 2 It is (0.2-3):1, can be optionally (0.5-1):1, can be further optionally (0.79-1):1, can be further optionally 1:

1.

5. The gel electrolyte battery according to any one of claims 1 to 4, wherein The crosslinking ratio CX of the gel part of the first gel electrolyte to the gel part of the second gel electrolyte is 1 / 2 It is 1:(1~5), can be optionally 1:(1.1~2.0), further can be optionally 1:(1.5~2.0), and further can be optionally 1:(1.8~2.0).

6. The gel electrolyte battery according to any one of claims 1 to 5, wherein The swelling ratio Q of the gel part of the first gel electrolyte relative to the swelling ratio Q of the gel part of the second gel electrolyte is 1 / 2 It is (1-4):1, can be optionally (1.3-2.5):1, can be further optionally (1.65-2.0):1, and can be further optionally (1.8-2.0):

1.

7. The gel electrolyte battery according to any one of claims 1 to 6, wherein The thermal decomposition temperature ratio Td of the gel part of the first gel electrolyte relative to the thermal decomposition temperature ratio Td of the gel part of the second gel electrolyte 1 / 2 It is 1:(1~4), can be optionally 1:(1.1~2.0), further can be optionally 1:(1.45~2.0), and further can be optionally 1:(1.6~1.8).

8. The gel electrolyte battery according to any one of claims 1 to 7, wherein The first gel electrolyte and the second gel electrolyte each contain an electrolyte salt; The ratio f1 of the mass proportion of the electrolyte salt in the first gel electrolyte to f2 of the mass proportion of the electrolyte salt in the second gel electrolyte is f 1 / 2 It is 1.5:1 to 1:1.5, and can be optionally 1:(0.7~1.5), further optionally 1:(0.8~1), and further optionally 1:(0.8~0.95).

9. The gel electrolyte battery according to claim 8, wherein: The gel electrolyte battery meets one or more of the following characteristics: The mass proportion f1 of the electrolyte salt in the first gel electrolyte is 0.7 to 1.2 mol / L, and can be optionally 0.8 to 1.2 mol / L; The mass ratio of the electrolyte salt in the second gel electrolyte is 0.7 to 1.2 mol / L, and can be optionally 0.8 to 1.2 mol / L.

10. The gel electrolyte battery according to any one of claims 1 to 9, wherein At least a portion of the first gel electrolyte is located between the second gel electrolyte and the positive electrode plate, and at least a portion of the first gel electrolyte is also located between the second gel electrolyte and the negative electrode plate.

11. The gel electrolyte battery according to any one of claims 1 to 10, wherein The gel electrolyte also includes a third gel electrolyte, which is located in at least part of the third region and the fourth region; wherein the third region is a gap region between negative electrode active materials in the negative electrode plate, and the fourth region is a gap region between positive electrode active materials in the positive electrode plate.

12. The gel electrolyte battery according to claim 11, wherein The mass ratio m of the gel portion of the first gel electrolyte to the gel portion of the third gel electrolyte is 1 / 3 It is 1:(4~10), can be optionally 1:(4~8), and can further be optionally 1:(4~6).

13. The gel electrolyte battery according to any one of claims 1 to 12, wherein At least a portion of the second gel electrolyte is in contact with at least a portion of the first region and the second region.

14. The gel electrolyte battery according to any one of claims 1 to 13, wherein The electrode assembly further includes a separator, which is disposed between the positive electrode plate and the negative electrode plate, and the second gel electrolyte is located outside the separator.

15. The gel electrolyte battery according to claim 14, wherein The gel electrolyte further includes a fourth gel electrolyte located in internal pores of the isolation membrane.

16. The gel electrolyte battery according to claim 15, wherein: The mass ratio m of the gel portion of the second gel electrolyte to the gel portion of the fourth gel electrolyte is 2 / 4 It is (4-9):1, can be optionally (5-9):1, and can further be optionally (6-8):

1.

17. The gel electrolyte battery according to any one of claims 1 to 16, wherein The gel electrolyte battery further comprises a shell, wherein the electrode assembly and the electrolyte are both located inside the shell; The electrolyte may or may not include a fifth gel electrolyte, and may or may not include a sixth gel electrolyte, wherein the fifth gel electrolyte is located on at least a portion of the outermost surface of the electrode assembly, and the sixth gel electrolyte is located on at least a portion of the relative space between the outermost surface of the electrode assembly and the inner wall of the shell, and the cross-linking degree of the sixth gel electrolyte is higher than that of the fifth gel electrolyte.

18. The gel electrolyte battery according to claim 17, wherein: The ratio of the sum of the gel portion mass m5 of the fifth gel electrolyte and the gel portion mass m6 of the sixth gel electrolyte to the sum of the gel portion mass m1 of the first gel electrolyte and the gel portion mass m2 of the second gel electrolyte satisfies 0≤(m5+m6) / (m1+m2)≤12.5%, optionally satisfies 0≤(m5+m6) / (m1+m2)≤10%, further optionally satisfies 4%≤(m5+m6) / (m1+m2)≤12.5%, further optionally satisfies 5%≤(m5+m6) / (m1+m2)≤12.5%, and further optionally satisfies 5%≤(m5+m6) / (m1+m2)≤10%.

19. The gel electrolyte battery according to any one of claims 1 to 18, wherein The electrolyte may or may not include a liquid electrolyte; optionally, the mass ratio of the gel part of the gel electrolyte to the liquid electrolyte is 1:(0-0.06), further optionally 1:(0.01-0.05), and further optionally 1:(0.02-0.04).

20. The gel electrolyte battery according to any one of claims 1 to 19, wherein The positive electrode sheet comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active substance, and the positive electrode active substance comprises a lithium ion material; Optionally, the electrolyte salt in the electrolyte includes a lithium salt; further optionally, the electrolyte salts in the first gel electrolyte and the second gel electrolyte each independently include a lithium salt; Optionally, the electrolyte comprises a lithium salt in a liquid electrolyte.

21. A method for preparing a gel electrolyte battery, comprising the following steps: The electrode assembly is installed into the shell, wherein The electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet; Injecting a first liquid injection material into the shell, wherein the first liquid injection material includes a first electrolyte salt, a first polymerizable monomer and a first solvent; To be formed; The first injection material is subjected to a curing reaction to form a first gel electrolyte on at least a portion of the surface of the positive electrode sheet and the negative electrode sheet; Injecting a second liquid injection material into the shell, wherein the second liquid injection material includes a second electrolyte salt, a second polymerizable monomer, and a second solvent; The second injection material is subjected to a curing reaction to form a second gel electrolyte in at least a portion of the relative space between the positive electrode plate and the negative electrode plate; wherein the crosslinking degree of the gel part of the second gel electrolyte is higher than the crosslinking degree of the gel part of the first gel electrolyte.

22. The preparation method according to claim 21, wherein The mass concentration of the first polymerizable monomer in the first injection material is recorded as c1, and the mass concentration of the second polymerizable monomer in the second injection material is recorded as c2, wherein c1 <c2; Optionally, the mass concentration of the first polymerizable monomer in the first injection material is 2% to 6%, and further optionally 3% to 5%; Alternatively, the mass concentration of the second polymerizable monomer in the second injection material is 5% to 10%, and further optionally 8% to 10%.

23. The preparation method according to claim 21 or 22, wherein: The mass ratio of the first injection material to the second injection material is (1-9):1; Optionally, the mass ratio of the first injection material to the second injection material is (2-6):

1.

24. The preparation method according to any one of claims 21 to 23, wherein The gel electrolyte battery prepared by the preparation method is as defined in any one of claims 1 to 20.

25. An electrical device comprising at least one of the gel electrolyte battery according to any one of claims 1 to 20 and the gel electrolyte battery prepared by the preparation method according to any one of claims 21 to 23.

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