Negative electrode layer structure for manganese-based positive electrode system and battery

Abstract

The utility model discloses a negative electrode layer structure for a manganese-based positive electrode system, which sequentially comprises a negative electrode material layer and a capsule layer from at least one side of a current collector layer to the outside, the capsule layer consists of a capsule body, and the capsule body comprises a capsule shell layer for forming an SEI (solid electrolyte interface) film and a capsule core layer for capturing Mn < 2 + >. The utility model provides a negative electrode layer structure for a manganese-based positive electrode system and a battery, and effectively solves the problems that when the battery adopts the manganese-based positive electrode system, Mn < 2 + > damages an SEI (solid electrolyte interface) film, so that the circulation and rate performance of a battery cell is reduced, and the self-discharge phenomenon of the battery cell is aggravated. And the rate capability and the cycle capability of the battery are improved.

Description

Technical Field

[0001] This utility model belongs to the field of secondary battery technology, specifically relating to a negative electrode layer structure and battery for a manganese-based positive electrode system. Background Technology

[0002] With the increasing application of electronic products, batteries are also finding wider applications. Manganese-based cathode materials are frequently used due to their excellent electrochemical performance and low cost. However, manganese-based cathode systems are prone to the Jahn-Teller effect at high temperatures or high voltages, leading to the formation of Mn. 2+ And migrate to the negative electrode with the electrolyte, and the Mn that migrates there 2+ This will damage the SEI film structure on the negative electrode side, affecting the cell's cycle and rate performance, and exacerbating the cell's self-discharge. Therefore, how to avoid Mn 2+ Destroying the SEI membrane structure has become a hot research topic.

[0003] The conventional solution is to add a complexing agent to the electrolyte to adsorb the dissolved Mn. 2+ However, complexing agents are easily oxidized and reduced during battery charging and discharging, losing their complexing ability; at the same time, complexing agents uniformly distributed in the electrolyte cannot accurately adsorb Mn on the negative electrode side. 2+ It may also accidentally adsorb other effective ions on the positive electrode side, leading to cell failure; in addition, adsorbing Mn 2+ Subsequently, the generated compounds may also migrate with the electrolyte, thereby damaging the interface between the positive and negative electrodes. Therefore, there is an urgent need for a method to address the issue of Mn in manganese-based cathode systems. 2+ The problem of damaging the SEI film. Summary of the Invention

[0004] To address the problems existing in the prior art, this utility model provides a negative electrode layer structure and battery for a manganese-based cathode system, effectively solving the problem of Mn content in batteries using a manganese-based cathode system. 2+ Damage to the SEI film leads to a decrease in cell cycle and rate performance, as well as an increase in cell self-discharge. This improves the battery's rate performance and cycle capability.

[0005] This utility model discloses a negative electrode layer structure for a manganese-based positive electrode system, extending outward from at least one side of the current collector layer ( Figure 1 (Two sides), sequentially comprising a negative electrode material layer and a capsule layer, wherein the capsule layer is composed of a capsule body, and the capsule body includes a capsule shell layer for forming an SEI film and a capsule body for capturing Mn. 2+ The capsule core layer.

[0006] The present invention also provides a battery comprising the negative electrode layer structure proposed in this invention and a manganese-based positive electrode.

[0007] The mass ratio of the capsule core layer to the capsule shell layer is selected from (90-99):(10-1).

[0008] As some preferred options, the mass ratio of the capsule core layer to the capsule shell layer can be further preferred to be (96-99):(4-1). When the mass ratio of the capsule core layer to the capsule shell layer is (96-99):(4-1), it helps to obtain capsules with stronger adsorption and fixation capabilities, thereby better ensuring the integrity of the SEI membrane.

[0009] The thickness of the capsule layer is selected from 0.001μm to 10μm.

[0010] As a further option, the thickness of the capsule layer is preferably 0.005μm-8μm, 0.01μm-7μm, 0.05μm-5μm, or 0.1μm-3μm.

[0011] As a further option, the thickness of the capsule layer is preferably 0.5μm-2μm.

[0012] As a further option, the particle size of the capsule is selected from 1μm-6μm.

[0013] As a further preferred embodiment, the particle size of the capsule is selected from 2μm-4μm.

[0014] The negative electrode material layer includes a negative electrode active material layer disposed on the current collector side. The placement of the negative electrode active material layer ensures the integrity of the negative electrode sheet structure and lays the foundation for further improvements to the negative electrode sheet.

[0015] As a further option, the negative electrode active material layer can be set as one or more layers, and the active materials between different layers can be different. The setting of multiple negative electrode active material layers helps to utilize the unique energy storage capacity, energy density and mechanical strength of different negative electrode active materials to achieve mutual cooperation between different negative electrode active materials, thereby increasing the specific capacity of the battery, enhancing cycle life and optimizing electrochemical performance.

[0016] As some preferred embodiments, the number of layers of the negative electrode active material is preferably 1-3.

[0017] As a further option, the negative electrode material layer may also be provided with one or more functional coatings with different functions from the side of the negative electrode active material layer outward. The establishment of functional coatings helps to specifically modify or optimize various performance aspects of the battery, thereby effectively improving battery performance.

[0018] As an optimization, the functionalized coating is preferably in 2-4 layers.

[0019] As a further option, in the functionalized coating, the coating used to achieve a certain function can be set as one or more layers, and the materials between different layers can be different.

[0020] As some preferred embodiments, the coating used to achieve a certain function preferably has 2-4 layers.

[0021] As a further embodiment, the negative electrode material layer also includes an adhesive layer, which is disposed on the side of the negative electrode active material layer close to the current collector, in order to further improve the adhesion between the current collector and the negative electrode active material layer and ensure the integrity of the electrode structure during battery cycling.

[0022] As a further option, the adhesive layer can be configured as one or more layers, with different adhesive materials between different layers.

[0023] As some preferred embodiments, the adhesive layer is preferably 2-4 layers.

[0024] As a further embodiment, the functionalized coating may include one or more conductive additive layers and / or negative electrode protective layers, with the conductive additive layer and / or negative electrode protective layer arranged sequentially from the negative electrode active material layer side outwards.

[0025] As some preferred embodiments, the negative electrode layer structure, from the current collector outwards, sequentially includes two binder layers, two negative electrode active material layers, two conductive additive layers, two negative electrode protective layers, and a capsule layer.

[0026] As some preferred embodiments, the negative electrode layer structure, from the current collector outward, sequentially includes two layers of negative electrode active material, two layers of negative electrode protective layer, and a capsule layer.

[0027] As some preferred embodiments, the negative electrode layer structure, from the current collector outward, sequentially includes two binder layers, two negative electrode active material layers, two conductive additive layers, and a capsule layer.

[0028] As a further option, the capsule shell material is selected from any one of organic solid electrolytes, inorganic solid electrolytes, and inorganic compounds that can form an SEI film.

[0029] As a further option, the inorganic solid electrolyte is selected from any one of oxide-based solid electrolytes, sulfide-based solid electrolytes, nitride-based solid electrolytes, halide-based solid electrolytes, and hydride-based solid electrolytes.

[0030] As a further option, the capsule core layer is selected from Mn 2+ Chelating agent or Mn 2+ Any one of the adsorbents.

[0031] As a further solution, the Mn 2+ The chelating agent is selected from any one of carboxylic acid chelating agents, carbonate or bicarbonate salts.

[0032] As a further option, the carboxylic acid chelating agent is selected from any one of aminocarboxylic acid chelating agents, dicarboxylic acid chelating agents, and tricarboxylic acid chelating agents.

[0033] As a further solution, the Mn 2+ The adsorbent is selected from any one of carbon-based adsorbents, nano-adsorbents, and polymer adsorbents.

[0034] As a further option, the carbon-based adsorbent is selected from any one of graphene oxide, reduced graphene oxide, and biochar.

[0035] As a further option, the biochar is selected from any one of wood biochar, straw biochar, fruit shell biochar, and algal biochar.

[0036] As a further option, the method of preparing the capsule is not limited. Technicians can choose the appropriate preparation method according to their needs, including but not limited to any one of the following methods: sol-gel method, self-assembly technology, interfacial polymerization, emulsion polymerization, and layer-by-layer self-assembly method.

[0037] As a further option, the construction method of the capsule layer is not limited. Technicians can choose the appropriate method to coat the capsule body onto the negative electrode material layer according to their needs. The method includes, but is not limited to, any one of the following: roller coating, blade coating, gravure coating, spray coating, electrophoretic deposition, spin coating, and dip coating.

[0038] As a further option, the coating method is selected from any one of dense coating, dot coating, or block coating.

[0039] As a further option, the current collector is selected from either metal foil or non-metallic materials.

[0040] As a further option, the metal foil is selected from any one of copper, nickel, stainless steel, titanium, and aluminum.

[0041] As a further option, the non-metallic material is selected from either conductive polymers or conductive glass.

[0042] As a further option, the material of the negative electrode active material layer is selected from any one of carbon-based materials, silicon-based materials, tin-based materials, lithium titanate, and lithium metal.

[0043] As a further option, the conductive additive layer material is selected from any one of carbon-based materials, metallic materials, and conductive polymers.

[0044] As a further solution, the carbon-based material is selected from any one of carbon black, graphite, carbon nanomaterials, graphene, activated carbon, carbon fiber, and carbon spheres.

[0045] As a further solution, the conductive polymer is selected from any one of main-chain conjugated polymers and non-conjugated conductive polymers.

[0046] As a further solution, the negative electrode protective layer material is selected from any one of metal oxides, fluorides, and nitrides.

[0047] As a further solution, the binder layer material is selected from any one of fluororesin binders and fluororubber binders.

[0048] As a further solution, the manganese-based positive electrode battery further includes a positive electrode.

[0049] As a further solution, the positive electrode includes a positive electrode current collector and a manganese-based positive electrode active material layer.

[0050] As a further solution, the manganese-based positive electrode active material layer includes a manganese-based positive electrode active material, a positive electrode binder, and a positive electrode conductive agent.

[0051] As a further solution, the manganese-based positive electrode active material is selected from layered manganese oxides (R s MnO2, where R is selected from Na, K, Li, Ca, Mg, and 0 ≤ s ≤ 1), manganese nickel cobalt oxides (NCM, LiNi f MnjCogO2, where f + j + g = 1, 0 ≤ f ≤ 1, 0 ≤ j ≤ 1, 0 ≤ g ≤ 1), nickel cobalt manganese aluminum oxides (NCA, LiNi h Co k Al m O2, where h + k + m ≈ 1, 0 < h, k, m < 1), manganese-based oxides, and manganates.

[0052] As a further solution, the positive electrode binder includes at least one of thermoplastic resins, acrylic resins, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0053] As a further solution, the positive electrode conductive agent includes crystalline carbon materials and amorphous carbon materials.

[0054] As a further solution, the positive electrode current collector is provided with a substrate layer.

[0055] As a further solution, the positive electrode current collector may also be provided with a functional coating.

[0056] As a further option, the metal foil layer is selected from one or more of aluminum, nickel, tin, copper, and stainless steel.

[0057] As a further option, the functional coating is not limited, and technicians can select different functional coatings according to their needs.

[0058] As a further embodiment, the battery also includes a separator disposed between the positive and negative electrodes.

[0059] As a further option, the diaphragm is selected from either a ceramic diaphragm or a polymer electrolyte diaphragm.

[0060] As a further embodiment, the manganese-based cathode battery also includes an electrolyte disposed between the cathode and the anode.

[0061] As a further embodiment, the electrolyte may also include a solvent, an inorganic electrolyte salt, and an organic electrolyte salt.

[0062] As a further option, the solvent is selected from at least one of ether compounds, acetal compounds, and ketal compounds.

[0063] Compared with the prior art, the present invention has at least the following beneficial effects:

[0064] The negative electrode layer structure for manganese-based cathode systems provided by this invention introduces a core-shell structured capsule layer, combined with a negative electrode material layer and current collector offering various options, to achieve a structure that effectively prevents Mn from entering the cathode. 2+ It disrupts the negative electrode layer structure of the SEI film.

[0065] (1) The presence of the capsule shell layer in the capsule layer enables pre-film formation on the negative electrode side, which not only effectively improves the stability of the solid electrolyte interphase (SEI) film, but also prevents Mn from forming. 2+ The co-intercalation of these components improves the battery's cycle life. Furthermore, pre-filming effectively reduces unnecessary side reactions in the electrolyte, thereby optimizing the battery's electrochemical performance and increasing energy and power density.

[0066] (2) In the capsule layer, the presence of the capsule core layer can effectively adsorb and fix Mn migrating from the positive electrode side. 2+ This prevents them from continuing to migrate with the electrolyte. This not only helps reduce the accumulation of transition metal ions on the negative electrode side and the potential side reactions, but also reduces the risk of these metal ions being reduced on the negative electrode side, thus avoiding potential safety hazards. Attached Figure Description

[0067] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0068] Figure 1 This is a diagram of the negative electrode layer structure in Example 1;

[0069] Figure 2 This is a diagram of the negative electrode layer structure in Example 11;

[0070] Figure 3 This is a diagram of the negative electrode layer structure in Example 12;

[0071] Figure 4 This is a diagram of the negative electrode layer structure in Example 13;

[0072] Figure 5 This is a structural diagram of capsule body 4;

[0073] Figure 6 The capacity retention rate during cycling at room temperature (0.33°C) is shown in Example 1 and Comparative Example 1.

[0074] Among them, 1-capsule layer; 2-negative electrode material layer; 21-negative electrode active material layer; 22-functionalized coating; 221-conductive additive layer; 222-negative electrode protective layer; 23-binder layer; 3-current collector; 4-capsule body; 41-capsule shell layer; 42-capsule core layer. Detailed Implementation

[0075] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be given below in conjunction with the accompanying drawings, and embodiments of this utility model will be provided, but this does not limit the scope of this utility model.

[0076] This utility model discloses a negative electrode layer structure for a manganese-based positive electrode system, such as... Figure 1 From at least one side of the current collector layer outwards ( Figure 1 (Two sides), comprising, in sequence, a negative electrode material layer 2 and a capsule layer 1. The capsule layer 1 is composed of a capsule body 4, which includes a capsule shell layer 41 for forming an SEI film and a capsule body 41 for capturing Mn. 2+ The capsule core layer 42.

[0077] First, the presence of the capsule shell 41 allows the capsule layer 1 to form an SEI film on the negative electrode side of the battery in advance, thereby effectively improving the stability and uniformity of the SEI film and preventing Mn from forming. 2+ It is embedded during the natural formation of the SEI membrane; secondly, it is used to capture Mn after the capsule shell 41 breaks. 2+The capsule core layer 42 is released. Since the capsule shell layer 41 has formed an SEI film on the surface of the negative electrode material layer in advance, the released capsule core layer 42 will gather near the electrolyte side, capturing and fixing Mn migrating from the positive electrode side. 2+ To avoid Mn 2+ Safety risks arising from reduction on the negative electrode side.

[0078] The present invention also provides a battery comprising the negative electrode layer structure proposed in this invention and a manganese-based positive electrode.

[0079] The mass ratio of the capsule core layer 42 to the capsule shell layer 41 is selected from (90-99): (10-1).

[0080] As some preferred options, the mass ratio of the capsule core layer 42 to the capsule shell layer 41 can be further preferred to be (96-99):(4-1). When the mass ratio of the capsule core layer 42 to the capsule shell layer 41 is (96-99):(4-1), it helps to obtain a capsule layer 1 with stronger adsorption and fixation capacity, thereby better ensuring the integrity of the SEI membrane.

[0081] The thickness of capsule layer 1 is selected from 0.001 μm to 10 μm. When the thickness of capsule layer 1 is greater than 10 μm, the excessively thick capsule layer 1 may lead to increased resistance, thus affecting battery performance; while when the thickness of capsule layer 1 is less than 0.001 μm, it may be impossible to pre-construct a stable SEI film, and it may also be difficult to meet the requirements for Mn adsorption. 2+ Therefore, the thickness of capsule layer 1 is selected from 0.001μm to 10μm to meet the requirements.

[0082] As a further option, the thickness of the capsule layer 1 is preferably 0.005μm-8μm, 0.01μm-7μm, 0.05μm-5μm, or 0.1μm-3μm. The thickness of the capsule layer 1 will affect its internal resistance, the stability of the constructed SEI film, and the resistance to Mn. 2+ The adsorption capacity of the SEI membrane gradually increases with the increase of the thickness of capsule layer 1, and the stability of the constructed SEI membrane also increases, particularly for Mn. 2+ As the adsorption capacity of SEI membrane gradually increases, the internal resistance also increases simultaneously. Therefore, a balance must be struck between the stability of the SEI membrane and the adsorption capacity of Mn. 2+ For adsorption capacity and internal resistance, the thickness of capsule layer 1 is preferably 0.005μm-8μm, 0.01μm-7μm, 0.05μm-5μm, or 0.1μm-3μm.

[0083] As a further improvement, the thickness of the capsule layer 1 is preferably 0.5 μm-2 μm, specifically 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, and 2 μm. When the thickness of the capsule layer 1 is 0.5 μm-2 μm, it helps to obtain higher SEI film stability and Mn... 2+ The capsule layer 1 has both adsorption capacity and lower internal resistance.

[0084] The particle size of the capsule body 4 is selected from 1μm-6μm. The particle size of 1μm-6μm can ensure the uniform distribution of the capsule body 4 on the capsule layer 1 and construct a capsule layer 1 with appropriate density.

[0085] As a further preferred embodiment, the particle size of the capsule body 4 is selected from 2μm-4μm. When the particle size of the capsule body 4 is selected from 2μm-4μm, it helps to further optimize the capsule body distribution.

[0086] The negative electrode material layer 2 includes a negative electrode active material layer 21 disposed on the current collector 3 side. The placement of the negative electrode active material layer 21 ensures the integrity of the negative electrode sheet structure and lays the foundation for further improvement of the negative electrode sheet.

[0087] As a further option, the negative electrode active material layer 21 can be configured as one or more layers, and the active materials between different layers can be different. The configuration of multiple negative electrode active material layers 21 helps to utilize the unique energy storage capacity, energy density and mechanical strength of different negative electrode active materials to achieve mutual cooperation between different negative electrode active materials, thereby increasing the specific capacity of the battery, enhancing cycle life and optimizing electrochemical performance.

[0088] As some preferred solutions, the number of negative electrode active material layers 21 is preferably 1-3 layers. When the number of negative electrode active material layers 21 is 1-3 layers, the unique advantages of different negative electrode active materials can be fully utilized, and different negative electrode active materials can be combined with each other to optimize battery performance. At the same time, the phenomenon of increased internal stress caused by the increase of the thickness of negative electrode active material layers 21 can be avoided. Therefore, the number of negative electrode active material layers 21 is preferably 1-3 layers.

[0089] As a further option, the negative electrode material layer 2 may also be provided with one or more functional coatings 22 with different functions from one side of the negative electrode active material layer 21 outward. The establishment of functional coatings 22 helps to specifically modify or optimize various performance aspects of the battery, thereby effectively improving battery performance.

[0090] As an optimization, the functionalized coating 22 is preferably 2-4 layers.

[0091] As a further option, in the functional coating 22, the coating used to achieve a certain function can be set as one or more layers, and the materials between different layers can be different.

[0092] As some preferred solutions, the coating used to achieve a certain function preferably has 2-4 layers. The number of layers of 2-4 layers helps to ensure low resistance while giving full play to the synergistic effect between different materials, thereby optimizing battery performance.

[0093] As a further embodiment, the negative electrode material layer 2 also includes an adhesive layer 23, which is disposed on the side of the negative electrode active material layer 21 close to the current collector 3, in order to further improve the adhesion between the current collector 3 and the negative electrode active material layer 21 and ensure the integrity of the electrode structure during battery cycling.

[0094] As a further option, the adhesive layer 23 can be configured as one or more layers, and the adhesive materials between different layers are different.

[0095] As some preferred embodiments, the adhesive layer 23 is preferably 2-4 layers, which helps to fully utilize the interaction between different adhesive materials and improve battery cycle capability.

[0096] As some preferred embodiments, the functionalized coating 22 may include one or more layers of conductive additive layer 221 and / or negative electrode protective layer 222, and from the negative electrode active material layer 21 outwards, the conductive additive layer 221 and / or negative electrode protective layer 222 are sequentially arranged. The conductive additive layer 221 refers to the functionalized coating 22 disposed on the electrode to improve the conductivity of the electrode. The placement of the conductive additive layer 221 helps to provide additional electron transport paths and improve the conductivity of the electrode. The negative electrode protective layer 222 refers to the coating disposed on the negative electrode sheet to protect the negative electrode material from the erosion of the electrolyte and other side reactions. The placement of the negative electrode protective layer 222 helps to reduce side reactions between the electrolyte and the electrode material, stabilize the electrode surface, and extend the battery cycle life.

[0097] As some preferred embodiments, the negative electrode layer structure (e.g.) Figure 2 From the current collector 3 outwards, it includes two layers of adhesive 23, two layers of negative electrode active material 21, two layers of conductive additive 221, two layers of negative electrode protective layer 222, and capsule layer 1.

[0098] As some preferred embodiments, the negative electrode layer structure (e.g.) Figure 3 From the current collector 3 outwards, it includes two layers of negative electrode active material 21, two layers of negative electrode protective layer 222, and capsule layer 1 in sequence.

[0099] As some preferred embodiments, the negative electrode layer structure (e.g.) Figure 4From the current collector 3 outwards, it includes two layers of adhesive 23, two layers of negative electrode active material 21, two layers of conductive additive 221, and capsule layer 1.

[0100] As a further option, the material of the capsule shell 41 is selected from any one of organic solid electrolytes, inorganic solid electrolytes, and inorganic compounds that can form an SEI film.

[0101] As a further option, the organic solid electrolyte is selected from any one of polyethylene glycol, poly(ethylene oxide), polyvinyl fluoride, polymethyl methacrylate, polyacrylic acid, and polyphosphate.

[0102] As a further option, the inorganic solid electrolyte is selected from any one of oxide-based solid electrolytes, sulfide-based solid electrolytes, nitride-based solid electrolytes, halide-based solid electrolytes, and hydride-based solid electrolytes.

[0103] As a further option, the oxide-based solid electrolyte is selected from Li3PO4N. X LiBO2N X , LiNbO3, LiTaO3, Li2SiO3, Li5La3Ta2O 12 Li7La3Zr2O 12 Li6BaLa2Ta2O 12 Li 3.6 Si 0.6 P 0.4 O 4、 Li 1.3 Al 0.3 Ti 1.7 Any one of (PO4)3 (LATP).

[0104] As a further option, the sulfide-based solid electrolyte is selected from any one of lithium sulfide, germanium sulfide, and phosphorus sulfide.

[0105] As a further option, the nitride-based solid-state electrolysis is selected from LiPON, Li3N, Li7PN4, and LiSi2N3.

[0106] The halide solid electrolyte is selected from LiX, Li2MX4, Li3M'X6, Li x M"yLn zOne or more of Cl3, LiKCl5X"; wherein X is one or more of F, Cl, Br, I, M is one or more of Mg, Mn, Fe, Zn, and Cd, M' is one or more of O, In, Y, Yb, Sc, Ho, Er, M" is one or more of Ta, Zr, Ca, and Al, Ln is one or more of La, Ce, Pr, Nd, and Sm, K is selected from one or more of La, Ta, and Nb, X" is selected from O, Cl, F, or OH, and H is selected from one or more of Y, Er, Yb, Ho, and Lu; wherein, O <x<1,0<y<1,0<z<1。

[0107] As a further option, the hydride solid electrolyte is selected from Li3AlH6, LiBH4, LiNH2, Li2NH, and combinations thereof.

[0108] As a further option, the inorganic compound is selected from either lithium carbonate or lithium phosphate.

[0109] As a further option, the capsule core layer 42 is selected from Mn 2+ Chelating agent or Mn 2+ Any one of the adsorbents.

[0110] As a further solution, the Mn 2+ The chelating agent is selected from any one of carboxylic acid chelating agents, carbonate or bicarbonate salts.

[0111] As a further option, the carboxylic acid chelating agent is selected from any one of aminocarboxylic acid chelating agents, dicarboxylic acid chelating agents, and tricarboxylic acid chelating agents.

[0112] As a further embodiment, the aminocarboxylic acid chelating agent is selected from any one of the following: disodium ethylenediaminetetraacetate, trisodium aminotriacetate, diethyltriaminepentaacetic acid, ethylene glycol bis(2-aminoethyl ether)tetraacetic acid, ethylenediaminetetraacetic acid, N-hydroxyethyl ethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, N,N-dihydroxyethylglycine, N-(hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, and N-methylaminoacetic acid.

[0113] As a further option, the dicarboxylic acid chelating agent is selected from any one of oxalic acid, maleic acid, succinic acid, fumaric acid, phthalic acid, succinic acid, and tartaric acid.

[0114] As a further option, the tricarboxylic acid chelating agent is selected from either citric acid or ammonium citrate.

[0115] As a further option, the carbonate or bicarbonate salt is selected from any one of potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate.

[0116] As a further solution, the Mn 2+ The adsorbent is selected from any one of carbon-based adsorbents, nano-adsorbents, and polymer adsorbents.

[0117] As a further option, the carbon-based adsorbent is selected from any one of graphene oxide, reduced graphene oxide, and biochar.

[0118] As a further option, the biochar is selected from any one of wood biochar, straw biochar, fruit shell biochar, and algal biochar.

[0119] As a further option, wood biochar refers to biochar prepared from wood through pyrolysis, wherein the wood biochar is selected from any one of oak biochar, maple biochar, cherry biochar, hickory biochar, walnut biochar, pear biochar, birch biochar, peach biochar, elm biochar, pine biochar, eucalyptus biochar, willow biochar, poplar biochar, elm biochar, fir biochar, and bamboo charcoal.

[0120] As a further option, straw biochar refers to biochar prepared from various crop straws, wherein the straw biochar is selected from any one of wheat straw biochar, corn straw biochar, rice straw biochar, sorghum straw biochar, soybean straw biochar, cotton straw biochar, peanut vine biochar, rapeseed straw biochar, sugarcane bagasse biochar, barley straw biochar, oat straw biochar, tomato straw biochar, potato straw biochar, sunflower seed straw biochar, and buckwheat straw biochar.

[0121] As a further option, algal biochar refers to biochar that converts algal biomass into carbon material through a pyrolysis process, wherein the algal biochar is selected from any one of Chlorella biochar, brown algae biochar, cyanobacterial biochar, red algae biochar, green algae biochar, and microalgae biochar.

[0122] As a further option, the preparation method of the capsule body 4 is not limited. Technicians can choose the appropriate preparation method according to their needs, including but not limited to any one of the following: sol-gel method, self-assembly technology, interfacial polymerization, emulsion polymerization, and layer-by-layer self-assembly method. The sol-gel method is an effective technique for preparing capsules. It involves forming uniformly dispersed nanoparticles in a solution, followed by controlled precipitation and polymerization to form capsules. The self-assembly technology typically involves first controlling the chemical reaction conditions to allow the raw materials to spontaneously form the capsule core layer 42. Then, by changing the reaction environment, another material is deposited on the surface of the capsule core layer 42 to form the capsule shell layer 41. This process usually involves non-covalent interactions between molecules, such as hydrogen bonds, electrostatic forces, and van der Waals forces.

[0123] Interfacial polymerization involves placing two liquid monomers in an oil phase and an aqueous phase, respectively. When these two phases come into contact, the monomers polymerize at the interface, forming a layer 41 that coats the outside of the capsule core layer 42, thus obtaining the capsule body 4. Emulsion polymerization prepares the capsule body 4 by first mixing monomers, emulsifiers, and water to form an emulsion. Then, an initiator initiates the polymerization reaction, causing the monomer molecules to gradually polymerize in the emulsion to form the capsule core layer 42. After the capsule core layer 42 is stably suspended in the emulsion, another monomer is added to the system, and further emulsion polymerization forms the capsule shell layer 41 on the outer layer of the core. Finally, layer-by-layer self-assembly is also a widely used method for preparing the capsule body 4. First, the capsule core layer 42 is synthesized using chemical or physical methods. Then, a shell material is deposited layer by layer on its surface, allowing the capsule shell layer 41 material to uniformly cover the surface of the capsule core layer 42 through self-assembly, ultimately obtaining the capsule body 4.

[0124] As a further option, the construction method of the capsule layer 1 is not limited. Technicians can choose an appropriate method to coat the capsule body 4 onto the negative electrode material layer 2 according to requirements. This method includes, but is not limited to, any one of the following: roller coating, blade coating, gravure coating, spray coating, electrophoretic deposition, spin coating, and dip coating. Roller coating refers to a method of uniformly coating slurry onto the current collector 3 using a roller. The roller typically has an application roller and a coating roller, and the slurry thickness is controlled by adjusting the roller speed and gap. Blade coating typically uses a blade to uniformly coat the slurry onto the surface of the current collector 3, and the gap between the blade and the current collector 3 can precisely control the coating thickness. Gravure coating refers to using a coating roller with grooves to transfer the slurry from the grooves onto the current collector 3. Spray coating is a method of using a spray gun to spray liquid paint onto the surface of an object, using compressed air or other gases to propel the paint. The coating material is atomized into tiny particles and uniformly covered on the object to be coated, enabling rapid and large-area coating; electrophoretic deposition is a method that uses an electric field to drive particles in the coating to move in a solution and uniformly deposit them on the surface of a conductive substrate, achieving uniform coating thickness; spin coating is a coating technique that involves dropping coating onto the center of a rotating substrate and using centrifugal force to spread the coating evenly on the substrate surface, suitable for preparing thin films and uniform coatings; dip coating is a method that involves immersing an object in a coating tank and then lifting it at a constant speed to uniformly cover the object's surface with coating.

[0125] As a further embodiment, the roller coating method involves the following steps:

[0126] The prepared negative electrode slurry is introduced into the slurry supply system, and the slurry is uniformly coated onto the surface of the copper foil by rollers. After coating, it is dried and compacted.

[0127] The gap between the rollers is selected from any one of 0.001μm-10μm, 0.005μm-8μm, 0.01μm-7μm, 0.05μm-5μm, 0.1μm-3μm, and 0.2μm-2μm, and the roller speed is selected from 30-60r / min.

[0128] As a further option, the coating method is selected from any one of dense coating, dot coating, and block coating. Dense coating refers to the coating layer forming a uniform and continuous coverage layer on the substrate surface without obvious gaps or discontinuities; dot coating refers to the coating material being distributed on the substrate surface in the form of dots, with possible gaps between the dots. Block coating refers to the coating material existing on the substrate surface in a block form, which may cover most of the surface but is not necessarily continuous. Each of the three coating methods has its advantages, and during operation, technicians can choose different coating methods according to their needs.

[0129] As a further option, the current collector 3 is selected from either metal foil or non-metallic materials.

[0130] As a further option, the metal foil is selected from any one of copper, nickel, stainless steel, titanium, and aluminum.

[0131] As a further option, the non-metallic material is selected from either conductive polymers or conductive glass.

[0132] As a further option, the conductive polymer is selected from any one of polyaniline, polypyrrole, polythiophene, poly(p-phenylenevinylene), polyacetylene, and poly(3,4-ethylenedioxythiophene).

[0133] As a further option, the conductive glass is selected from any one of indium tin oxide glass, fluorine-doped tin oxide glass, aluminum-doped zinc oxide glass, gallium-doped zinc oxide glass, and tin oxide glass.

[0134] As a further option, the negative electrode active material layer 21 is selected from any one of carbon-based materials, silicon-based materials, tin-based materials, lithium titanate, and lithium metal.

[0135] As a further option, the carbon-based material is selected from any one of artificial graphite, natural graphite, soft carbon, and hard carbon.

[0136] As a further option, the silicon-based material is selected from either elemental silicon or silicon oxide compounds.

[0137] As a further option, the silicon oxide compound is selected from silicon dioxide, SiO2, etc. r , 0 < r < 2, any one of Li2VSiO4, Li2FeSiO4, Li2MnSiO4, and Li2NiSiO4.

[0138] As a further option, the tin-based material is selected from any one of elemental tin, stannous oxide, tin dioxide, Sn2O3, and Sn3O4.

[0139] As a further option, the conductive additive layer 221 material is selected from any one of carbon-based materials, metallic materials, and conductive polymers.

[0140] As a further option, the carbon-based material is selected from any one of carbon black, graphite, carbon nanomaterials, graphene, activated carbon, carbon fiber, and carbon spheres.

[0141] As a further option, the carbon black is selected from any one of acetylene black, conductive carbon black, combustion black, and channel black.

[0142] As a further option, the graphite is selected from expanded graphite.

[0143] As a further option, the carbon nanotubes are selected from either single-walled carbon nanotubes or multi-walled carbon nanotubes.

[0144] As a further option, the graphene is selected from any one of single-layer graphene, multilayer graphene, and fullerene.

[0145] As a further option, the activated carbon is selected from any one of microporous activated carbon, mesoporous activated carbon, and macroporous activated carbon.

[0146] As a further option, the carbon fiber is selected from either continuous carbon fiber or chopped carbon fiber.

[0147] As a further option, the carbon spheres are selected from either carbon microspheres or carbon nanospheres.

[0148] As a further option, the metal material is selected from any one of silver, copper, nickel, aluminum, iron, tin, rhodium, cobalt, palladium, platinum, titanium, antimony, manganese, tungsten, molybdenum, and stainless steel.

[0149] As a further option, the conductive polymer is selected from either a self-chain conjugated polymer or a non-conjugated conductive polymer.

[0150] As a further embodiment, the main chain conjugated polymer is selected from any one of polyaniline, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene), poly(3-hexylthiophene), polyacetylene, and polyfluorene.

[0151] As a further option, the non-conjugated conductive polymer is selected from either polyethylene terephthalate or polydiallyldimethylammonium chloride.

[0152] As a further option, the negative electrode protective layer 222 material is selected from any one of metal oxides, fluorides, and nitrides.

[0153] As a further option, the metal oxide is selected from any one of titanium dioxide, aluminum oxide, titanium dioxide, vanadium pentoxide, zirconium dioxide, silicon dioxide, tin dioxide, chromium oxide, nickel oxide, copper oxide, manganese oxide, cobalt oxide, iron oxide, cerium oxide, and lanthanum oxide.

[0154] As a further option, the fluoride is selected from any one of lithium fluoride, lithium hexafluorophosphate, boron trifluoride, nickel fluoride, sodium fluoride, aluminum fluoride, calcium fluoride, and high-fluoride lithium.

[0155] As a further option, the nitride is selected from any one of boron nitride, titanium nitride, aluminum nitride, silicon nitride, and gallium nitride.

[0156] As a further option, the adhesive layer 23 material is selected from any one of fluororesin adhesives and fluororubber adhesives.

[0157] As a further embodiment, the fluoropolymer adhesive is selected from any one of polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, ethylene-tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, chlorotrifluoroethylene copolymer, and polyvinyl fluoride.

[0158] As a further option, the fluororubber adhesive is selected from any one of vinylidene fluoride-hexafluoropropylene fluororubber, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluororubber, vinylidene fluoride-pentafluoropropylene fluororubber, vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluororubber, fluoromethyl vinyl ether-tetrafluoroethylene fluororubber, vinylidene fluoride fluororubber, and fluorinated trifluorochloroethylene fluororubber.

[0159] As a further embodiment, the battery also includes a positive electrode.

[0160] As a further embodiment, the positive electrode includes a positive electrode current collector and a manganese-based positive electrode active material layer.

[0161] As a further embodiment, the manganese-based positive electrode active material layer includes a manganese-based positive electrode active material, a positive electrode binder, and a positive electrode conductive agent.

[0162] As a further option, the manganese-based positive electrode active material is selected from layered manganese oxides (R... s MnO2, R is selected from Na, K, Li, Ca, Mg, 0≤s≤1), manganese nickel cobalt oxide (NCM, LiNi) fMnjCogO2, where f + j + g = 1, 0 ≤ f ≤ 1, 0 ≤ j ≤ 1, 0 ≤ g ≤ 1), lithium nickel cobalt manganese aluminum oxide (NCA, LiNi h Co k Al m O2, where h + k + m ≈ 1, 0 < h, k, m < 1), any one of manganese-based oxides and manganates.

[0163] As a further embodiment, the manganate is selected from any one of lithium manganate, lithium nickel manganate, lithium cobalt manganate, and sodium manganate.

[0164] As a further embodiment, the cathode binder includes at least one of a thermoplastic resin, an acrylic resin, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0165] As a still further embodiment, the thermoplastic resin includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride - hexafluoropropylene, a copolymer of tetrafluoroethylene - hexafluoropropylene, a copolymer of tetrafluoroethylene - perfluoroalkyl vinyl ether, a copolymer of ethylene - tetrafluoroethylene, a copolymer of vinylidene fluoride - tetrafluoroethylene, a copolymer of vinylidene fluoride - trifluoroethylene, a copolymer of vinylidene fluoride - trichloroethylene, a copolymer of vinylidene fluoride - fluoroethylene, a copolymer of vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene.

[0166] As a further embodiment, the acrylic resin includes at least one of an acrylic vinyl ester resin, an acrylic methyl ester resin, an acrylic butyl ester resin, an acrylic styrene resin, an acrylate resin, an acrylate copolymer resin, an acrylic resin, and an acrylic emulsion resin.

[0167] As a further embodiment, the cathode conductive agent includes a crystalline carbon material and an amorphous carbon material.

[0168] As a still further embodiment, the crystalline carbon material includes at least one of conductive graphite, carbon nanotubes, graphene, and reduced graphene oxide.

[0169] As a still further embodiment, the amorphous carbon material includes at least one of conductive carbon black, conductive carbon spheres, and conductive carbon fibers.

[0170] As a further embodiment, the cathode current collector is provided with a substrate layer.

[0171] As a further option, the positive electrode current collector may also have a functional coating. It is worth noting that the positive electrode current collector mentioned here can be either a metal current collector using only a metal foil layer as the substrate, such as using any one of aluminum foil, copper foil, nickel foil, tin foil, or stainless steel foil; or a composite current collector with a functional coating on the surface of the substrate. The functional coating can be a material with different characteristics, such as polyaniline, graphene, carbon nanotubes, titanium dioxide, or polyurethane. Here, the material of the functional coating is not limited, and technicians can select different functional coatings according to their needs.

[0172] As a further embodiment, the battery also includes a separator disposed between the positive and negative electrodes.

[0173] As a further option, the diaphragm is selected from either a ceramic diaphragm or a polymer electrolyte diaphragm.

[0174] As a further option, the ceramic diaphragm is selected from any one of alumina ceramic diaphragms, zirconia ceramic diaphragms, titanium dioxide ceramic diaphragms, silicon dioxide ceramic diaphragms, and magnesium aluminum spinel ceramic diaphragms.

[0175] As a further embodiment, the polymer electrolyte membrane is selected from any one of polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polyimide, polycarbonate, polyethylene terephthalate, polyetherimide, polyurethane, polybenzimidazole, polyvinyl alcohol, and polyphosphate.

[0176] As a further embodiment, the battery also includes an electrolyte disposed between the positive and negative electrodes.

[0177] As a further embodiment, the electrolyte may also include a solvent, an inorganic electrolyte salt, and an organic electrolyte salt.

[0178] As a further option, the solvent is selected from at least one of ether compounds, acetal compounds, and ketal compounds.

[0179] As a further embodiment, the ether solvent is selected from ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, ethylene glycol methyl ether ethyl ether, ethylene glycol diethyl ether, diethylene glycol methyl ether ethyl ether, diethylene glycol diethyl ether, triethylene glycol methyl ether ethyl ether, triethylene glycol diethyl ether, tetraethylene glycol methyl ether ethyl ether, tetraethylene glycol diethyl ether, ethylene glycol methyl ether propyl ether, ethylene glycol ethyl ether propyl ether, ethylene glycol dipropyl ether, diethylene glycol methyl ether propyl ether, diethylene glycol ethyl ether propyl ether, diethylene glycol dipropyl ether, triethylene glycol methyl ether propyl ether, triethylene glycol di ... At least one of the following: glycol ethyl ether propyl ether, triethylene glycol dipropyl ether, tetraethylene glycol methyl ether propyl ether, tetraethylene glycol ethyl ether propyl ether, tetraethylene glycol dipropyl ether, ethylene glycol methyl ether butyl ether, ethylene glycol ethyl ether butyl ether, ethylene glycol propyl ether butyl ether, ethylene glycol dibutyl ether, diethylene glycol methyl ether butyl ether, diethylene glycol ethyl ether butyl ether, diethylene glycol propyl ether butyl ether, diethylene glycol dibutyl ether, triethylene glycol methyl ether butyl ether, triethylene glycol ethyl ether butyl ether, triethylene glycol propyl ether butyl ether, triethylene glycol dibutyl ether, tetraethylene glycol methyl ether butyl ether, tetraethylene glycol ethyl ether butyl ether, tetraethylene glycol propyl ether butyl ether, and tetraethylene glycol dibutyl ether.

[0180] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0181] Example 1

[0182] Preparation of capsule body 4: Lithium carbonate was used as the capsule shell layer 41 and ethylenediaminetetraacetic acid (EDTA) was used as the capsule core layer 42. 9.5 g of EDTA and 0.5 g of lithium carbonate were added to a ball mill jar and ball milled for 2 h. After ball milling, the resulting mixture was transferred to a 50 mL crucible, placed in a tube furnace, and calcined at 300 °C for 3 h. After cooling to room temperature, capsule body 4 with a particle size of 3 μm was obtained.

[0183] Preparation of negative electrode: Capsule body 4, SiO2, and graphite were added to NMP solution and stirred for 2 hours to prepare a dispersion of capsule body 4, SiO2, and graphite with a solid content of 30%. Using copper foil as the current collector, the SiO2 dispersion, graphite dispersion, and capsule body 4 dispersion were sequentially coated onto the surface of the copper foil. The roller gap was 1 μm and the roller speed was 40 r / min. After each layer was coated, it was dried at 110℃ for 12 hours before the next layer was coated, until all the dispersions were coated.

[0184] Battery preparation: The prepared negative electrode sheet, the positive electrode sheet with Li2MnO3 as the positive electrode active material, and the polyethylene (PE)-Al2O3 composite separator are stacked together to form a dry cell. Then, after encapsulation, liquid injection, and formation, the experimental cell is obtained.

[0185] Example 2

[0186] The preparation method and process are the same as in Example 1, except that LATP is used as the capsule shell 41.

[0187] Example 3

[0188] The preparation method and process are the same as in Example 1, except that ammonium citrate is used as the capsule core layer 42.

[0189] Example 4

[0190] The preparation method and process are the same as in Example 1, except that the capsule material dispersion 4 is prepared using the melt droplet method. The steps of the melt droplet method are as follows: In an argon atmosphere, ethylenediaminetetraacetic acid is heated to 300°C until it is completely melted to obtain a melt. This melt is then placed in a sealed reaction vessel, and lithium hydroxide solution and carbon dioxide gas (the molar ratio of lithium hydroxide to carbon dioxide is 2:1, and the mass ratio of lithium carbonate to ethylenediaminetetraacetic acid generated is 95:5) are added to the reaction vessel. The mixture is heated and kept at a constant temperature of 300°C and stirred for 1 hour to disperse it into small droplets. When the temperature drops to 100°C, the droplets are dropped into NMP solution through a sieve to obtain the capsule material dispersion prepared by the melt droplet method.

[0191] Example 5

[0192] The preparation method and process are the same as in Example 1, except that the mass of ethylenediaminetetraacetic acid is 9.8g and the mass of lithium carbonate is 0.2g.

[0193] Example 6

[0194] The preparation method and process are the same as in Example 1, except that the particle size of the prepared capsule body 4 is 4μm.

[0195] Example 7

[0196] The preparation method and process are the same as in Example 1, except that the thickness of capsule layer 1 is 0.5 μm.

[0197] Example 8

[0198] The preparation method and process are the same as in Example 1, except that the thickness of capsule layer 1 is 2 μm.

[0199] Example 9

[0200] The preparation method and process are the same as in Example 1, except that lithium manganese oxide is used as the positive electrode active material.

[0201] Example 10

[0202] The preparation method and process are the same as in Example 1, except that lithium cobalt manganese oxide is used as the positive electrode active material.

[0203] Example 11

[0204] The preparation method and process are the same as in Example 1, except that when preparing the negative electrode sheet, an adhesive layer 23 (polytetrafluoroethylene, polychlorotrifluoroethylene), a negative electrode active material layer 21 (SiO2, graphite), a conductive additive layer 221 (graphene, conductive carbon black), and a negative electrode protective layer 222 (copper oxide, lithium fluoride) are sequentially coated outward from the current collector 3 side.

[0205] Example 12

[0206] The preparation method and process are the same as in Example 1, except that when preparing the negative electrode sheet, the negative electrode active material layer 21 (SiO2, graphite) and the negative electrode protective layer 222 (copper oxide, lithium fluoride) are coated sequentially outward along the current collector 3 side.

[0207] Example 13

[0208] The preparation method and process are the same as in Example 1, except that when preparing the negative electrode sheet, an adhesive layer 23 (polytetrafluoroethylene and polychlorotrifluoroethylene), a negative electrode active material layer 21 (SiO2 and graphite), and a conductive additive layer 221 (graphene and conductive carbon black) are sequentially coated outward from the current collector 3 side.

[0209] Comparative Example 1

[0210] The preparation method and process are the same as in Example 1, except that the capsule layer is not coated.

[0211] Comparative Example 2

[0212] The preparation method and process are the same as in Example 1, except that ethylenediaminetetraacetic acid is not added when preparing capsule body 4, and the amount of lithium carbonate used is 10g.

[0213] Comparative Example 3

[0214] The preparation method and process are the same as in Example 1, except that lithium carbonate is not added when preparing capsule body 4, and the amount of ethylenediaminetetraacetic acid is 10g.

[0215] Comparative Example 4

[0216] The preparation method and process are the same as in Example 11, except that the capsule layer 1 is not coated.

[0217] Comparative Example 5

[0218] The preparation method and process are the same as in Example 11, except that lithium carbonate is not added when preparing capsule body 4, and the amount of ethylenediaminetetraacetic acid is 10g.

[0219] Comparative Example 6

[0220] The preparation method and process are the same as in Example 12, except that the capsule layer 1 is not coated.

[0221] Comparative Example 7

[0222] The preparation method and process are the same as in Example 12, except that ethylenediaminetetraacetic acid is not added and the amount of lithium carbonate used is 10g.

[0223] Comparative Example 8

[0224] The preparation method and process are the same as in Example 13, except that the capsule layer 1 is not coated.

[0225] Comparative Example 9

[0226] The preparation method and process are the same as in Example 13, except that ethylenediaminetetraacetic acid is not added and the amount of lithium carbonate used is 10g.

[0227] Comparative Example 10

[0228] The preparation method and process are the same as in Example 9, except that the capsule layer 1 is not coated.

[0229] Comparative Example 11

[0230] The preparation method and process are the same as in Example 10, except that the capsule layer 1 is not coated.

[0231] Test methods

[0232] Loop test flow:

[0233] First, charge at a constant current of 0.33C to 4.5V, and then charge at a constant voltage of 4.5V until the current is less than or equal to 0.05C;

[0234] After a 10-minute rest period, the circuit was discharged at a constant current of 0.33C to 1.5V, followed by another 10-minute rest period. This cycle was repeated 283 times, and the capacity retention rate at 0.33C was plotted.

[0235] Capacity retention rate (%) = (Capacity after initial capacity cycle) × 100%.

[0236] The Mn content in the bottom layer of the negative electrode sheet was tested using energy-dispersive X-ray spectroscopy (EDS).

[0237] The experimental parameters for Examples 1-13 and Comparative Examples 1-11 are shown in Table 1, and the test results are shown in Table 2.

[0238] Table 1

[0239]

[0240]

[0241]

[0242] Table 2

[0243]

[0244] As can be observed from Examples 1-13 and Comparative Examples 1-11, the Mn content in the bottom layer of the negative electrode sheet after cycling in Examples 1-13 is much lower than that in Comparative Examples 1-11, indicating that the negative electrode layer structure used in the manganese-based positive electrode system can effectively avoid Mn. 2+ Because of the embedding, Examples 1-13 exhibit better capacity retention than Comparative Examples 1-11.

[0245] As can be observed from Examples 1, 11, 4, 12, 6, 13, and 8, Examples 1, 11, 12, and 13 significantly exhibit better capacity retention rates after 283 cycles than Comparative Examples 1, 4, 6, and 8. This is because the proposed negative electrode layer structure can form a stable SEI film to avoid Mn. 2+ Embedded during the natural formation of the SEI membrane, the presence of the capsule core layer 42 also helps to capture and immobilize migrating Mn. 2+ This protects the integrity of the SEI membrane structure and improves the cycling capacity retention rate. After 283 cycles, Examples 1, 11, 12 and 13 showed cycling capacity retention rates of 85.23%, 89.32%, 88.7% and 86.54%, respectively.

[0246] As observed in Examples 1, 2, 3, 11, 5, 12, 7, 13, and 9, the presence of the capsule body 4, composed of a core layer 42 and a shell layer 41, is of great significance for improving the capacity retention of the manganese-based cathode battery system. As observed in Comparative Examples 2, 7, and 9, when the core layer 42 is absent, although the shell layer 41 simultaneously forms an SEI film on the surface of the negative electrode, it does not necessarily prevent the formation of a MnO2-containing electrolyte. 2+ Mn is embedded during the natural formation of the SEI film; however, with continuous battery cycling, Mn... 2+ Mn continuously migrates from the positive electrode to the negative electrode, lacking the ability to capture it. 2+ Capsule core layer 42, Mn migrated from 2+It may still damage the SEI film structure, thereby affecting the battery cycle capacity retention rate. On the other hand, as observed from Comparative Examples 3 and 5, when only the capsule core layer 42 is present, the Mn content at the bottom layer of the negative electrode sheet in Comparative Examples 3 and 5 after cycling is 0.86% and 0.94%, respectively, which is higher than 0.25% and 0.20% in Examples 1 and 11. Due to the lack of a pre-constructed SEI film, although the capsule core layer 42 can capture and fix the Mn migrating from the positive electrode during the natural formation of the SEI film, it is still insufficient. 2+ However, some Mn may still exist. 2+ When the negative electrode is embedded, the Mn content at the bottom layer of the negative electrode increases after cycling, which affects the cycle capacity retention rate.

[0247] As observed in Examples 1, 9, and 10, when different manganese-based materials are used as the positive electrode active material, although different manganese-based positive electrode materials exhibit different cycle capacity retention rates, the Mn content in the bottom layer of the negative electrode sheet does not exceed 0.3% after cycling. In contrast, in Comparative Examples 1, 10, and 11, the Mn content in the bottom layer of the negative electrode sheet exceeds 1% after cycling. This indicates that regardless of the manganese-based material chosen as the positive electrode active material, a high Mn content may exist when the negative electrode sheet structure proposed in this scheme is not adopted. 2+ The negative electrode is embedded during cycling, which affects the cycle performance of the battery.

[0248] Examples 1, 2, and 3 demonstrate the effects of different materials used to prepare the capsule core layer 42 and capsule shell layer 41 on battery performance. As can be observed from Examples 1, 2, and 3, regardless of whether the ethylenediaminetetraacetic acid material of the capsule core layer 42 is replaced with ammonium citrate or the lithium carbonate material of the capsule shell layer 41 is replaced with LATP, Examples 1, 2, and 3 all exhibit excellent capacity retention. This indicates that replacing the materials used to prepare the capsule core layer 42 and capsule shell layer 41 does not affect the performance of the negative electrode structure proposed in this scheme.

[0249] Examples 1 and 4 demonstrate the impact of capsules 4 prepared by different methods on the battery cycle capacity retention when used to construct the negative electrode layer structure. From Examples 1 and 4, it can be observed that Example 1 achieved a capacity retention of 85.23% after 283 cycles, while Example 4 achieved a capacity retention of 85.74% after 283 cycles. This data also indicates that different preparation methods of capsules 4 do not affect the performance of the negative electrode layer structure. Whether it is Example 1 prepared by dry coating or Example 5 prepared by molten droplet method, both methods effectively protect the negative electrode sheet and prevent Mn from spreading. 2+ Embedded in the cycle, it disrupts the SEI membrane structure.

[0250] Examples 1 and 5 demonstrate the impact of different mass ratios of the capsule core layer to the capsule shell layer on the battery cycle capacity retention. When the mass ratio of the capsule core layer 42 to the capsule shell layer 41 is 98:2, Example 5 exhibits a better cycle capacity retention (86.27%) and a lower Mn content in the bottom layer of the negative electrode after cycling (0.13%). This may be because increasing the proportion of the capsule core layer 42 helps to further intercept and fix Mn migrating from the positive electrode. 2+ This better ensures the integrity of the SEI membrane, and therefore, after 283 cycles, Example 5 exhibits better cycle capacity retention.

[0251] Controlling the capsule particle size helps regulate the density of the capsule layer 1, thereby affecting the battery's cycle capacity retention. As observed in Examples 1 and 6, when the capsule particle size is 3 μm, Example 1 exhibits a higher cycle capacity retention than Example 6. This may be because a 3 μm capsule 4 helps to construct a denser capsule layer 1, thus better intercepting and immobilizing Mn migrating from the positive electrode. 2+ This provides better protection for the SEI membrane.

[0252] Examples 1, 7, and 8 demonstrate the effect of the thickness of capsule layer 1 on battery performance. When the thickness of capsule layer 1 is selected as 1 μm, Example 1 exhibits better cycle capacity retention than Examples 2 and 8. This may be because a capsule layer thickness of 1 μm helps to obtain higher SEI film stability and stronger Mn content. 2+ Adsorption capacity; at the same time, the capsule layer 1 with a thickness of only 1 μm can obtain lower internal resistance, thereby improving the cycle capacity retention rate. Therefore, as can be observed from Example 8, although the Mn content of the bottom layer of the negative electrode sheet in Example 8 is only 0.23% after 283 cycles, Example 1 shows a higher cycle capacity retention rate (85.18%).

[0253] Examples 1 and 11 illustrate the influence of different layer structures on the performance of the negative electrode layer. Example 1 is shown in [reference needed]. Figure 1 See Example 11 Figure 2 ,Depend on Figure 2It is known that when the negative electrode layer structure includes, from the current collector 3 outwards, two layers of binder layer 23, two layers of negative electrode active material layer 21, two layers of conductive additive layer 221, two layers of negative electrode protective layer 222, and capsule layer 1, Example 11 exhibits a better cycle capacity retention rate than Example 1. Simultaneously, the Mn content of the negative electrode sheet after cycling is also better than that of Example 1. This may be because, on the one hand, the establishment of binder layer 23, conductive additive layer 221, and negative electrode protective layer 22 helps to further improve battery performance; the presence of binder layer 23 helps to improve battery stability; the setting of conductive additive layer 221 helps to improve battery conductivity; and the negative electrode protective layer 22 further provides protection for the negative electrode. Therefore, after cycling, Example 11 exhibits a better Mn content in the bottom layer of the negative electrode sheet than Example 1. Secondly, the double-layered binder layer 23, conductive additive layer 221, and negative electrode protective layer 222 help to further disperse internal stress, thereby improving battery stability. Therefore, the cycle capacity retention rate of Example 11 is better than that of Example 1.

[0254] Figure 3 The diagram illustrates the negative electrode layer structure, from the current collector 3 outwards, comprising two layers of negative electrode active material 21, two layers of negative electrode protective layer 222, and a capsule layer 1. A comparison of Examples 1 and 12 shows that Example 12 also exhibits better cycle capacity retention than Example 1. This may be because the presence of the negative electrode protective layer 222 helps to further protect the battery negative electrode and prevent Mn from entering the battery. 2+ The embedding of [material name] improves the cycle capacity retention rate. In addition, its dual-layer structure also helps to disperse internal stress and leverage the synergistic effect between different materials, thereby optimizing battery performance.

[0255] Figure 4 The structure of Example 13 is shown in the figure. When the negative electrode active material includes two layers of binder layer 23, two layers of negative electrode active material layer 21, two layers of conductive additive layer 221, and capsule layer 1 from the current collector 3 outwards, Example 4 also shows a high cycle capacity retention rate. From Example 1 and Example 13, it can be observed that the cycle capacity of Example 13 is 86.54%, while the cycle capacity of Example 1 is 85.23%. This may be due to the presence of two layers of binder layer 23 and two layers of conductive additive layer 221 in Example 13. On the one hand, the presence of binder layer 23 and conductive additive layer 221 helps to improve the battery stability and conductivity. On the other hand, the double-layer binder layer 23 and conductive additive layer 221 also help to exert the compounding effect of their different interlayer materials, thereby improving the cycle capacity retention rate.

[0256] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

Claims

1. A negative electrode layer structure for a manganese-based positive electrode system, characterized in that, From at least one side of the current collector layer outward, it includes a negative electrode material layer (2) and a capsule layer (1) in sequence. The capsule layer (1) is composed of a capsule body (4); The capsule body (4) includes a capsule shell layer (41) for forming an SEI membrane and a capsule core layer (42). The negative electrode material layer (2) includes a negative electrode active material layer (21) disposed on the current collector (3) side. The negative electrode material layer (2) is further provided with a functional coating (22) from the negative electrode active material layer (21) outward. The negative electrode material layer (2) also includes an adhesive layer (23), which is disposed on the side of the negative electrode active material layer (21) close to the current collector (3); The number of layers of the negative electrode active material layer (21) is 1-3; The functionalized coating (22) consists of 2-4 layers; The adhesive layer (23) consists of 2-4 layers; The functionalized coating (22) is provided with a conductive additive layer (221) and / or a negative electrode protective layer (222), and from the negative electrode active material layer (21) outward, the conductive additive layer (221) and / or the negative electrode protective layer (222) are in sequence.

2. The negative electrode layer structure according to claim 1, characterized in that, The thickness of the capsule layer (1) is selected from 0.001μm-10μm.

3. The negative electrode layer structure according to claim 1, characterized in that, The thickness of the capsule layer (1) is selected from 0.005μm-8μm.

4. The negative electrode layer structure according to claim 1, characterized in that, The thickness of the capsule layer (1) is selected from 0.01μm-7μm.

5. The negative electrode layer structure according to claim 1, characterized in that, The thickness of the capsule layer (1) is selected from 0.05μm-5μm.

6. The negative electrode layer structure according to claim 1, characterized in that, The thickness of the capsule layer (1) is selected from 0.1μm-3μm.

7. The negative electrode layer structure according to claim 1, characterized in that, The thickness of the capsule layer (1) is selected from 0.5μm-2μm.

8. The negative electrode layer structure according to claim 1, characterized in that, The capsule shell (41) material is selected from any one of organic solid electrolytes, inorganic solid electrolytes, and inorganic compounds that form SEI films. The inorganic solid electrolyte is selected from any one of oxide-based solid electrolytes, sulfide-based solid electrolytes, nitride-based solid electrolytes, halide-based solid electrolytes, and hydride-based solid electrolytes.

9. A battery, characterized in that, It includes the negative electrode layer structure as described in any one of claims 1-8.

10. The battery according to claim 9, characterized in that, It also includes a positive electrode, which includes a positive electrode current collector and a manganese-based positive electrode active material layer.

11. The battery according to claim 10, characterized in that, The positive electrode current collector includes a substrate layer and a functional coating.

12. The battery according to claim 9, characterized in that, It also includes a diaphragm and electrolyte placed between the positive and negative electrodes.

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