A battery and an electric device
By introducing silicon particles and specific additives into lithium-ion batteries to form a composite SEI film, the problem of cycle performance degradation of lithium-ion batteries under high and low temperature environments has been solved, achieving high energy density, excellent comprehensive electrochemical performance and safety reliability of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN HIGHPOWER TECH CO LTD
- Filing Date
- 2026-02-02
- Publication Date
- 2026-05-29
AI Technical Summary
Lithium-ion batteries exhibit significant degradation in cycle performance under high and low temperature environments. In particular, lithium plating occurs at low temperatures and side reactions at the electrode/electrolyte interface accelerate at high temperatures, leading to battery reliability and safety issues.
Silicon particles are introduced into the negative electrode active material layer, and acid anhydrides, carbonates, silanes and sulfonates are added to the electrolyte as additives to form a composite SEI film, which synergistically improves lithium-ion transport and interface stability.
Significantly extends battery cycle life, improves high-temperature storage stability and safety, enhances rate performance, and maintains high energy density.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochemical energy storage technology, specifically to a battery and an electrical device. Background Technology
[0002] Lithium-ion batteries have become the core power source for electric vehicles, energy storage systems, and portable electronic devices due to their advantages such as high energy density, long cycle life, and no memory effect. However, in practical applications, batteries often need to operate in a wide temperature range (such as 0°C to 60°C or even higher), and the significant degradation of cycle performance under high and low temperature environments has become a key technical bottleneck restricting their reliability, safety, and service life.
[0003] At low temperatures (such as below 0°C), the viscosity of traditional carbonate electrolytes increases sharply and the ionic conductivity decreases significantly. Simultaneously, the solid-state diffusion kinetics of lithium ions in the positive and negative electrode materials are severely restricted, leading to increased battery polarization and a sharp decrease in reversible capacity. More seriously, during low-temperature charging, lithium ions struggle to embed into negative electrode materials such as graphite in a timely manner, easily resulting in irreversible lithium deposition (lithium plating) on the surface. This not only causes loss of active lithium and reduces the initial coulombic efficiency but may also induce lithium dendrites to penetrate the separator, triggering internal short circuits or even thermal runaway.
[0004] At high temperatures (e.g., above 45°C), although the ion transport rate increases, the side reactions at the electrode / electrolyte interface are significantly accelerated: high-capacity cathode materials such as high-nickel or lithium-rich manganese-based materials are prone to transition metal ion reactions (e.g., Ni...). 2+ Mn 4+ Dissolution, lattice oxygen release, and irreversible phase transition occur. The electrolyte continuously oxidizes and decomposes at high potentials, reacting catalytically with dissolved metal ions to form a thick, high-resistivity positive electrolyte interphase (CEI) film. Simultaneously, conventional SEI films exhibit insufficient thermal stability at high temperatures, easily rupturing and repeatedly regenerating, continuously consuming lithium and electrolyte, leading to rapid capacity decay, increased internal resistance, and even safety risks such as gas generation and bulging. If trace amounts of moisture or HF are present in the system, high temperatures will further exacerbate positive electrode corrosion, binder degradation, and current collector corrosion, further deteriorating cycle stability.
[0005] To address the above challenges, existing technologies are mainly improved through the following approaches: Electrolyte additive optimization: such as adding fluoroethylene carbonate (FEC) to enhance SEI thermal stability, or introducing low-melting-point solvents to improve low-temperature fluidity; Cathode material doping / coating: such as using elements like Al, Ti, and Mg to stabilize the crystal structure; Anode material modification: such as using hard carbon, silicon-carbon composite materials, or pre-lithiation strategies to mitigate lithium desorption issues.
[0006] However, these methods generally suffer from limitations, offering only a single function and compromising on other aspects. For example, while FEC can improve high-temperature SEI stability, it results in high film-forming resistance at low temperatures and is prone to over-polymerization at high temperatures, leading to interface passivation. Low-viscosity solvents, while improving low-temperature performance, often sacrifice high-voltage stability or safety. Furthermore, while simple magnesium doping can suppress cathode structure degradation, without a matching interface protection mechanism, it cannot effectively prevent electrolyte oxidation and metal dissolution at high temperatures, nor can it solve the low-temperature lithium plating problem. Therefore, overcoming these technical problems and shortcomings is a key issue that needs to be addressed. Summary of the Invention
[0007] In view of the problem that the cycle performance of lithium-ion batteries deteriorates significantly under high and low temperature environments in the prior art, the present invention provides a battery and an electrical device.
[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: This invention provides a battery, comprising: A negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, the negative electrode active material comprising a negative electrode active material comprising silicon particles; An electrolyte comprising a first additive, a second additive, a third additive, and a fourth additive, wherein the first additive comprises an acid anhydride compound, the second additive comprises a carbonate compound, the third additive comprises a silane compound, and the fourth additive comprises a sulfonate compound.
[0009] Optionally, the mass content X of silicon particles in the negative electrode active material layer is expressed as a percentage, and the value of X ranges from 1 to 100.
[0010] Optionally, taking the total mass of the electrolyte as 100%, the mass percentage of the first additive in the electrolyte is denoted as A, in %, and the value of A ranges from 0.5 to 5; the mass percentage of the second additive in the electrolyte is denoted as B, in %, and the value of B ranges from 0.5 to 20; the mass percentage of the third additive in the electrolyte is denoted as C, in %, and the value of C ranges from 0.5 to 5; and the mass percentage of the fourth additive in the electrolyte is denoted as D, in %, and the value of D ranges from 0.5 to 5.
[0011] Optionally, the values of A, B, C, D, and X satisfy the following conditions: Equation 1: 0.05 ≤ (A+B+C) / X ≤ 23; Equation 2: 0.05≤D / (B+C)≤2; Equation 3: 0.13≤C / A≤4.5.
[0012] Optionally, the values of A, B, C, D, and X satisfy the following conditions: Equation 1: 0.1≤(A+B+C) / X≤10; Equation 2: 0.07≤D / (B+C)≤0.8; Equation 3: 0.17≤C / A≤4.
[0013] Optionally, the anhydride compound is selected from one or more of succinic anhydride, maleic anhydride, and glutaric anhydride.
[0014] Optionally, the carbonate compound is selected from one or more of vinylene carbonate and fluoroethylene carbonate.
[0015] Optionally, the silane compound is selected from one or more of tetravinylsilane and vinyltris(trimethylsiloxy)silane.
[0016] Optionally, the sulfonate compound is selected from one or more of 1,3-propanesulfonate lactone and 1,3-propenesulfonate lactone.
[0017] Optionally, it further includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer disposed on the positive current collector, the positive active material layer including a positive active material, the positive active material including one or more of transition metal lithium oxide, lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, and lithium vanadium phosphate.
[0018] Optionally, the chemical formula of the transition metal lithium oxide is Li 1+x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.
[0019] Another aspect of the present invention provides an electrical device comprising the battery described above.
[0020] According to the battery provided by the present invention, although the theoretical specific capacity can be significantly improved by introducing silicon particles into the negative electrode active material layer, it is prone to severe volume expansion during charging and discharging, leading to active material pulverization, electrode structure collapse, and repeated rupture and regeneration of the solid electrolyte interphase (SEI) film. The present invention introduces a first additive (an anhydride compound) into the electrolyte, which preferentially reduces the silicon particles during the first charge, forming a dense and flexible SEI film rich in organic carboxylates and inorganic lithium salts on the surface of the silicon particles. This effectively inhibits the continuous decomposition of the electrolyte and buffers the mechanical stress caused by silicon volume changes, thereby significantly extending the battery cycle life. Furthermore, by introducing a second additive (a carbonate compound) into the electrolyte, which works synergistically with the first additive, the inorganic / organic component ratio of the SEI film is further controlled, improving the ionic conductivity and electronic insulation of the film layer. This composite SEI film not only reduces interfacial impedance but also promotes uniform lithium-ion insertion / extraction, improves rate performance, reduces side reaction gas generation, and enhances the battery's high-temperature storage stability. The third additive (silane compound) of this invention has a bifunctional structure, with one end chemically bonded to the hydroxyl groups or oxide layer on the surface of silicon particles, and the other end participating in SEI film formation or interacting with the polymer binder. This molecular bridging effect significantly enhances the interfacial bonding force between silicon particles, current collectors, and binders, effectively inhibiting the shedding of active materials during cycling and maintaining the integrity of the electrode structure. The fourth additive (sulfonate ester compound) can undergo oxidative polymerization under high voltage or local overheating conditions, forming a protective film on the positive electrode surface, inhibiting transition metal dissolution and electrolyte oxidative decomposition. At the same time, its decomposition products can participate in the construction of a more stable SEI / CEI (cathode electrolyte interface) film, reducing the risk of internal short circuits and improving the battery's thermal stability and overcharge tolerance. Detailed Implementation
[0021] To make the technical problems solved, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.
[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.
[0023] In one embodiment, the present invention provides a battery comprising: A negative electrode sheet includes a negative current collector and a negative active material layer disposed on the negative current collector. The negative active material layer includes a negative active material, which includes silicon particles. The electrolyte includes a first additive, a second additive, a third additive, and a fourth additive. The first additive includes an acid anhydride compounds, the second additive includes carbonate compounds, the third additive includes silane compounds, and the fourth additive includes sulfonate compounds.
[0024] In one embodiment, the negative electrode active material layer includes a negative electrode active material, which includes, but is not limited to, one or more combinations of graphite, hard carbon, silicon, silicon suboxide, silicon-carbon composite material, and lithium titanate. It is preferably designed in conjunction with the positive electrode and functionalized electrolyte to maximize the overall performance of the battery. In this invention, there are no particular limitations on the negative electrode current collector, as long as it can achieve the purpose of this application. For example, it can be copper foil, copper alloy foil, magnesium foil, stainless steel foil, titanium foil, foamed magnesium, foamed copper, or composite current collector, etc.
[0025] In some preferred embodiments, the negative current collector comprises copper foil.
[0026] In some embodiments, the negative electrode active material layer is disposed on at least one side surface of the negative electrode current collector, and the negative electrode active material layer further includes a negative electrode conductive agent, a negative electrode binder, a negative electrode thickener, and a negative electrode solvent.
[0027] The negative electrode conductive agent includes at least one of the following carbon materials: natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.
[0028] Negative electrode binders include styrene-butadiene latex, etc. Negative electrode thickeners include CMC, etc. Negative electrode solvents include deionized water, etc.
[0029] In one embodiment, the electrolyte further includes a lithium salt, which includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium difluorophosphate, lithium bis(oxalate-borate), lithium difluorooxalate-borate, lithium tetrafluoroborate, and lithium difluorodi(oxalate-borate). Using the above-mentioned lithium salt has the effects of providing a stable lithium ion source, promoting the formation of a dense SEI film, and improving the ionic conductivity and thermal stability of the electrolyte.
[0030] It should be noted that this application does not impose any particular limitation on the preparation method of the electrolyte. Those skilled in the art can prepare the electrolyte using conventional technical means, such as mixing the raw materials evenly according to the specified ratio.
[0031] In one embodiment, the electrolyte further includes an organic solvent, which includes one or more of the following: ethylene carbonate, propylene carbonate, butene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, diphenyl carbonate, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, propyl acetate, ethyl butyrate, propyl propionate, γ-butyrolactone, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.
[0032] Specifically, the aforementioned organic solvents are selected primarily to dissolve the first additive, the second additive, the third additive, the fourth additive, and the lithium salt.
[0033] In one embodiment, a separator is also included, which is located between the positive electrode and the negative electrode.
[0034] This application does not impose any particular restrictions on the material and shape of the diaphragm, as long as it does not significantly impair the effectiveness of this application.
[0035] In some embodiments, the diaphragm includes a porous sheet-like or non-woven material with excellent liquid retention properties. The diaphragm includes resin or glass fiber diaphragm materials, including but not limited to polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc.
[0036] This invention introduces silicon particles into the negative electrode active material layer, which can significantly improve the theoretical specific capacity. However, these particles are prone to severe volume expansion during charge and discharge, leading to active material pulverization, electrode structure collapse, and repeated rupture and regeneration of the solid electrolyte interphase (SEI) film. This invention addresses this by introducing a first additive (an anhydride compound) into the electrolyte. This additive preferentially reduces the silicon particles during the first charge, forming a dense and flexible SEI film rich in organic carboxylates and inorganic lithium salts on the silicon particle surface. This effectively inhibits the continuous decomposition of the electrolyte and buffers the mechanical stress caused by silicon volume changes, thereby significantly extending the battery cycle life. Furthermore, by introducing a second additive (a carbonate compound) into the electrolyte, which works synergistically with the first additive, the inorganic / organic component ratio of the SEI film is further controlled, improving the ionic conductivity and electronic insulation of the film. This composite SEI film not only reduces interfacial impedance but also promotes uniform lithium-ion insertion / extraction, improves rate performance, reduces side reaction gas generation, and enhances the battery's high-temperature storage stability. The third additive (silane compound) of this invention has a bifunctional structure, with one end chemically bonded to the hydroxyl groups or oxide layer on the surface of silicon particles, and the other end participating in SEI film formation or interacting with the polymer binder. This molecular bridging effect significantly enhances the interfacial bonding force between silicon particles, current collectors, and binders, effectively inhibiting the shedding of active materials during cycling and maintaining the integrity of the electrode structure. The fourth additive (sulfonate ester compound) can undergo oxidative polymerization under high voltage or local overheating conditions, forming a protective film on the positive electrode surface, inhibiting transition metal dissolution and electrolyte oxidative decomposition. At the same time, its decomposition products can participate in the construction of a more stable SEI / CEI (cathode electrolyte interface) film, reducing the risk of internal short circuits and improving the battery's thermal stability and overcharge tolerance.
[0037] In summary, this invention effectively solves the key bottleneck problems of silicon-based anode materials, such as rapid cycle decay, low initial efficiency, and interface instability caused by volume expansion, through the synergistic design of "silicon-based anode + quaternary functional additive electrolyte". While maintaining high energy density, it achieves excellent comprehensive electrochemical performance and safety reliability, and is suitable for high-energy-density power batteries and energy storage systems.
[0038] In one embodiment, the mass content X of silicon particles in the negative electrode active material layer is expressed as a percentage, and the value of X ranges from 1 to 100.
[0039] Specifically, the mass content of silicon particles in the negative electrode active material layer is any one value or a range of any two values from 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%; in a preferred embodiment, the mass content of silicon particles in the negative electrode active material layer is 10%-50%.
[0040] When the mass content of silicon particles in the negative electrode active material layer is 1%-100%, the energy density of the battery can be significantly improved. Within this content range, silicon particles, as the main or auxiliary active component, can effectively contribute additional lithium storage capacity. Simultaneously, with the synergistic effect of the quaternary additive electrolyte used in this invention, a stable, flexible, and ionically conductive solid electrolyte interface (SEI) film can be constructed on the silicon surface. Furthermore, silane additives enhance the interfacial bonding between silicon particles and the binder / current collector, effectively mitigating the volume expansion effect (>300%) of silicon during charge and discharge, and suppressing particle pulverization and electrode structure collapse. When the mass content of silicon particles in the negative electrode active material layer is less than 1%, although the impact on electrode structure stability is small, its contribution to the overall capacity is negligible, making it difficult to achieve an effective improvement in energy density. More importantly, at such a low doping ratio, silicon particles often exist in an isolated and dispersed state, unable to form an effective conductive network or synergistic lithium storage mechanism. At the same time, since the silicon surface still irreversibly consumes lithium ions to form an SEI film, the initial irreversible capacity loss is relatively increased, and the initial coulombic efficiency decreases. Furthermore, the presence of trace amounts of silicon may introduce localized stress concentration points, which can induce microcrack propagation during long-term cycling, thereby reducing the mechanical integrity of the electrode and resulting in more harm than good.
[0041] In one embodiment, the total mass of the electrolyte is denoted as 100%. The mass percentage of the first additive in the electrolyte is denoted as A, with the unit being %, and the value of A ranges from 0.5 to 5. The mass percentage of the second additive in the electrolyte is denoted as B, with the unit being %, and the value of B ranges from 0.5 to 20. The mass percentage of the third additive in the electrolyte is denoted as C, with the unit being %, and the value of C ranges from 0.5 to 5. The mass percentage of the fourth additive in the electrolyte is denoted as D, with the unit being %, and the value of D ranges from 0.5 to 5.
[0042] Specifically, the first additive accounts for a mass percentage of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5% of the electrolyte, or a range of any two of these values; in a preferred embodiment, the first additive accounts for a mass percentage of 1%-4% of the electrolyte.
[0043] When the first additive accounts for 0.5%-5% of the electrolyte by mass, it preferentially undergoes a reduction reaction on the silicon-based negative electrode surface during the first charge of the battery, compared to conventional solvents (such as EC, DEC, etc.), forming a dense, flexible composite SEI film rich in organic carboxylic acid lithium and inorganic lithium salts in situ. This film exhibits excellent ion conductivity and electronic insulation, effectively inhibiting the continuous decomposition of the electrolyte, significantly reducing initial irreversible capacity loss, and improving initial coulombic efficiency. Simultaneously, this SEI film possesses good mechanical adaptability, effectively buffering the drastic volume expansion of silicon particles during charge and discharge, preventing the pulverization and shedding of active materials, thereby significantly extending the battery cycle life. Furthermore, an appropriate amount of anhydride additives can react with trace amounts of water or HF in the electrolyte, acting as a "deacid and water remover," improving the overall stability of the electrolyte. When the first additive accounts for less than 0.5% of the electrolyte by mass, its concentration is too low to form a continuous and complete SEI protective layer on the silicon particle surface. This results in some silicon surfaces being directly exposed to the electrolyte, leading to repeated solvent reduction and decomposition during cycling. This causes the SEI film to continuously rupture and regenerate, exacerbating the irreversible consumption of lithium ions and electrolyte, and triggering problems such as rapid increase in internal resistance, increased gas production, and accelerated capacity decay. Under these conditions, the battery's initial coulombic efficiency is significantly reduced, and its cycle stability fails to meet practical application requirements. When the first additive accounts for more than 5% of the electrolyte's mass, excessive anhydride compounds can cause multiple negative effects: on the one hand, excessive deposition of their reduction products leads to an excessively thick and dense SEI film, significantly increasing interfacial ion transport impedance and deteriorating rate performance; on the other hand, high-concentration anhydrides may react with lithium salts or other additives in the electrolyte to generate insoluble polymers or gaseous byproducts, affecting electrolyte clarity, conductivity, and battery safety; furthermore, excessive additives may oxidize on the cathode surface at high voltages, damaging the cathode / electrolyte interface stability and leading to overall battery performance degradation.
[0044] Specifically, the second additive accounts for a mass percentage of 0.5%, 2%, 3.5%, 5%, 6.5%, 8%, 9.5%, 11%, 12.5%, 14%, 15.5%, 17%, 18.5%, or 20% of the electrolyte, or a range of any two of these values; in a preferred embodiment, the second additive accounts for a mass percentage of 5%-15.5% of the electrolyte.
[0045] When the second additive accounts for 0.5%-20% of the electrolyte by mass, it can effectively participate in the construction of the SEI film during the first charge-discharge process, forming a stable interface layer rich in LiF, polycarbonate polymers, and organic lithium salts on the surface of silicon particles. Fluorocarbonate additives, especially FEC, can generate a high-mechanical-strength SEI film rich in LiF, significantly improving the film's tolerance to silicon volume expansion and inhibiting the continuous decomposition of the electrolyte. Within this content range, the SEI film exhibits both good ion conductivity and electronic insulation, effectively reducing interfacial impedance, improving the initial coulombic efficiency, and significantly improving the battery's long-cycle stability and high-temperature storage performance. Simultaneously, an appropriate amount of the second additive can also produce a synergistic effect with the first additive, further optimizing the multiphase structure of the SEI film and enhancing its self-healing ability. When the second additive accounts for less than 0.5% of the electrolyte by mass, its concentration is too low, making it difficult to form a sufficiently comprehensive and functional SEI protective layer on the silicon anode surface. This leads to conventional solvents (such as EC) dominating the SEI formation process, resulting in a film with poor density and insufficient flexibility, which cannot effectively adapt to changes in silicon volume and is prone to cracking during cycling, triggering continuous side reactions. The results are characterized by large initial irreversible capacity loss, low initial coulombic efficiency, and rapid cycle capacity decay, which may be accompanied by significant gas generation, seriously affecting the reliability and lifespan of the battery. When the second additive accounts for more than 20% of the electrolyte mass, although the SEI film is formed more fully, excessive addition will bring multiple adverse effects: On the one hand, high concentrations of carbonate additives will generate a large amount of LiF and polymers during the reduction process, resulting in an excessively thick SEI film and significantly increased impedance, which seriously hinders lithium-ion transport and deteriorates rate performance; on the other hand, some additives may undergo excessive polymerization or decomposition at high contents, generating gases (such as HF, CO2, etc.) or insoluble precipitates, causing battery swelling, increased internal pressure, and even safety risks; in addition, excessive additives will dilute the proportion of the main solvent, reduce the overall conductivity of the electrolyte, and may interfere with the normal function of other functional additives (such as silanes and sulfonates), disrupting the synergistic balance between additives.
[0046] Specifically, the third additive accounts for a mass percentage of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5% of the electrolyte, or a range of any two of these values; in a preferred embodiment, the third additive accounts for a mass percentage of 1%-4% of the electrolyte.
[0047] When the third additive accounts for 0.5%-5% of the electrolyte by mass, it can effectively adsorb and anchor onto the surface of silicon particles during battery formation. Through its siloxane groups, it forms stable Si-O-Si covalent bonds with the silicon active material, significantly enhancing the interfacial bonding between silicon particles and conductive agents, binders, and current collectors. Simultaneously, its organic functional groups can participate in the construction of the SEI film, introducing flexible organic components, improving the extensibility and self-adaptability of the interfacial film, effectively alleviating the volume expansion stress of silicon during charging and discharging, and inhibiting particle pulverization and electrode peeling. Within this content range, the battery exhibits excellent cycle stability, a low interfacial impedance growth rate, and good rate performance. Furthermore, an appropriate amount of silane additives can also improve the wettability of the electrolyte to the electrodes and promote uniform lithium-ion transport. When the third additive accounts for less than 0.5% of the electrolyte by mass, its concentration is too low to form an effective molecular bridging network on the silicon particle surface, resulting in weak interfacial modification. Silicon particles are still prone to detachment from surrounding components due to volume changes during cycling, leading to electrical contact failure, "deactivation" of active materials, and consequently, rapid capacity decay. Simultaneously, the SEI film lacks flexible organic support, increasing its brittleness and making it difficult to adapt to silicon deformation. Repeated breakage and regeneration exacerbate irreversible lithium loss, significantly reducing both initial coulombic efficiency and cycle life. When the third additive accounts for more than 5% of the electrolyte mass, excessive silane compounds may have negative effects: firstly, they may undergo self-condensation reactions in the electrolyte, generating insoluble siloxane polymer precipitates that block membrane pores or cover electrode active sites, hindering lithium-ion migration and leading to increased battery internal resistance and deteriorated rate performance; secondly, high concentrations of silanes may interfere with the reduction behavior of other functional additives (such as anhydrides and carbonates), disrupting the optimized composition of the SEI film and even causing side reactions on the positive electrode side, affecting overall battery compatibility; furthermore, some silanes have hydrophobic properties, and excessive addition may reduce the overall polarity and conductivity of the electrolyte, negatively impacting low-temperature battery performance.
[0048] Specifically, the fourth additive accounts for a mass percentage of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5% of the electrolyte, or a range of any two of these values; in a preferred embodiment, the fourth additive accounts for a mass percentage of 1%-4% of the electrolyte.
[0049] When the fourth additive accounts for 0.5%-5% of the electrolyte by mass, it preferentially undergoes oxidative decomposition on the surface of the positive electrode material (such as high-nickel ternary materials, lithium cobalt oxide, etc.) during charging, forming a dense and stable CEI film in situ. This film is rich in lithium sulfonate salts, sulfate ester polymers, and inorganic lithium salts, effectively inhibiting the dissolution of transition metal ions, electrolyte oxidative decomposition, and oxygen release, significantly improving the battery's high-temperature storage performance, cycle stability, and overcharge tolerance. Simultaneously, appropriate amounts of sulfonate ester additives can also participate in the optimization of the negative electrode SEI film, enhancing its thermal stability and producing a synergistic effect with the first, second, and third additives, constructing a more complete interface protection system. Within this content range, the battery exhibits excellent safety performance (e.g., passing nail penetration and overcharge tests), low gas generation rate, and good long-cycle retention. When the fourth additive accounts for less than 0.5% of the electrolyte by mass, its concentration is too low to form a continuous and effective CEI protective layer on the positive electrode surface. This leads to continuous oxidative decomposition of the electrolyte under high voltage, causing degradation of the positive electrode structure, increased impedance, and gas generation. Especially under high temperature or high voltage conditions, capacity decay accelerates, significantly increasing safety risks. Furthermore, due to the lack of sufficient interfacial protection, transition metal ions (such as Ni)... 4+ Mn 4+ The additive is easily dissolved and migrates to the negative electrode, damaging the stability of the SEI film and further aggravating the side reactions of the silicon-based negative electrode, resulting in the deterioration of the overall battery performance. When the fourth additive accounts for more than 5% of the electrolyte by mass, excessive addition will bring multiple negative effects: On the one hand, sulfonate compounds may overpolymerize at high concentrations, forming an excessively thick or highly insulating CEI film, significantly increasing the positive electrode interface impedance and deteriorating the rate performance and low-temperature discharge capability; on the other hand, some sulfonate compounds may also undergo side reactions at the negative electrode at the reduction potential, interfering with the normal construction of the SEI film and leading to a decrease in the first coulombic efficiency; in addition, high content of additives will dilute the proportion of the main solvent, reduce the conductivity of the electrolyte, and may cause safety problems such as increased internal pressure, swelling, or even leakage of the battery due to the accumulation of its own decomposition products.
[0050] In one embodiment, the values A, B, C, D, and X satisfy the following condition: Equation 1: 0.05 ≤ (A+B+C) / X ≤ 23; Equation 2: 0.05≤D / (B+C)≤2; Equation 3: 0.13≤C / A≤4.5.
[0051] Specifically, the value range of (A+B+C) / X is any one point value or any two point values from 0.05, 0.1, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21 or 23; in a preferred embodiment, the value range of (A+B+C) / X is 1-10.
[0052] When the value of (A+B+C) / X ranges from 0.05 to 23, it indicates a good match between the total amount of functional additives in the electrolyte and the silicon content. Within this range, anhydride, carbonate, and silane additives can work synergistically to construct a composite SEI film on the silicon particle surface that combines density, flexibility, and ion conductivity, and enhances the mechanical stability of the electrode through molecular bridging. Simultaneously, the supply of additives is sufficient to cover the fresh surface of silicon continuously exposed during cycling due to volume expansion, effectively suppressing side reactions and active material deactivation. Therefore, the battery exhibits high initial coulombic efficiency, excellent cycle retention, low gas production rate, and good rate performance, fully releasing the high capacity potential of the silicon-based anode. When the value of (A+B+C) / X is less than 0.05, it indicates a severe deficiency of functional additives relative to the silicon content. Even if the contents of the first, second, and third additives are within the conventional effective range, the excessively high silicon ratio results in insufficient interfacial protection components allocated per unit mass of silicon. The results are as follows: incomplete SEI film coverage, repeated rupture and regeneration, a sharp increase in irreversible lithium consumption, and a significant decrease in initial coulombic efficiency; silicon particles are easily pulverized and detached from the conductive network during cycling, resulting in rapid capacity decay; simultaneously, there is significant gas generation and an increase in internal resistance, making it difficult to guarantee battery life and safety; when the value of (A+B+C) / X is greater than 23, it indicates that the functional additives are seriously excessive relative to the silicon content. Although the silicon content is low, the total amount of the first, second, and third additives is too high, which may lead to the following problems: competitive side reactions between additives or with the main solvent / lithium salt, generating insoluble polymers or gases; excessive growth, excessive thickness, or excessively high impedance of the SEI film, hindering lithium-ion transport and deteriorating rate and low-temperature performance; increased electrolyte viscosity, decreased conductivity, and poor wettability; a significant increase in cost, and the decreased stability of some additives at high concentrations, which in turn reduces battery reliability. In this situation, although the cycle stability may be acceptable, the energy density is not effectively improved, while the overall performance (efficiency, kinetics, and safety) deteriorates, resulting in poor economy and practicality.
[0053] Specifically, the value of D / (B+C) is any one value or a range of any two values from 0.05, 0.1, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9 or 2; in a preferred embodiment, the value of D / (B+C) is 0.3-1.7.
[0054] When the value of D / (B+C) is in the range of 0.05-2, it indicates that the positive electrode film-forming additive and the negative electrode interface synergistic additive are in a good matching state. Within this range, the fourth additive can effectively form a stable and dense cathode electrolyte interface (CEI) film on the positive electrode surface, inhibiting electrolyte oxidation, transition metal dissolution, and gas generation under high voltage. At the same time, the second and third additives construct a flexible SEI film with excellent lithium conductivity on the silicon-based negative electrode side and enhance the interparticle binding force. The synergistic effect of the two achieves "synchronous optimization of the positive and negative electrode interfaces", significantly improving the overall performance of the full battery under high voltage, high temperature, or long cycle conditions. The battery exhibits high initial coulombic efficiency, low impedance growth, excellent cycle retention, and good safety characteristics (such as passing overcharge and hot box tests). When the value of D / (B+C) is less than 0.05, it indicates that the fourth additive (D) is seriously insufficient relative to the negative electrode functional additives, the second and third additives (B+C). At this point, although the negative electrode interface is well protected, the positive electrode lacks an effective CEI film coverage, making it prone to electrolyte oxidation and decomposition, positive electrode structural degradation, and oxygen release during high-voltage charging. This is especially true in high-nickel or lithium cobalt oxide systems, where transition metal ions (such as Ni...) can cause significant damage. 4+ Co 4+ Excessive dissolution and migration to the negative electrode disrupts the stability of the SEI film, triggering a "cross-contamination" effect. This leads to rapid capacity decay, a sharp increase in internal resistance, severe gas production, and even an increased risk of thermal runaway. Consequently, the battery's high-voltage adaptability and long-term reliability significantly decrease. When the value of D / (B+C) is greater than 2, it indicates an excess of the fourth additive (D), while the second and third additives (B+C), the interface control components of the negative electrode, are relatively insufficient. In this case, although the positive electrode CEI film may be relatively intact, the negative electrode (especially the high-proportion silicon negative electrode) lacks sufficient support from the second and third additives (B+C), making it difficult to form a high-quality SEI film and effectively buffer the volume expansion of silicon. The results are: high negative electrode interface impedance, low initial efficiency, and active material pulverization and shedding during cycling. At the same time, excessive fourth additive (D) may cause unexpected reduction side reactions at the negative electrode, generating high-impedance or gaseous byproducts. In addition, high concentrations of sulfonate additives may reduce electrolyte conductivity, increase viscosity, and deteriorate rate and low-temperature performance. Ultimately, the performance of the full battery is limited by the weakness of the negative electrode, and the overall energy efficiency and cycle life decrease instead of increase.
[0055] Specifically, the value of C / A is any one value or a range of any two values from 0.13, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8, 2.1, 2.4, 2.7, 3, 3.3, 3.6, 3.9, 4.2 or 4.5; in a preferred embodiment, the value of C / A is 0.6-3.9.
[0056] When the C / A ratio ranges from 0.13 to 4.5, it indicates a highly efficient synergistic relationship between silane additives (C) and anhydride additives (A). Within this range, anhydride compounds preferentially reduce to form a dense SEI substrate rich in lithium carboxylate and inorganic salts, providing excellent ion conductivity and electronic insulation. Simultaneously, silane compounds form stable Si-O-Si covalent bonds with the silicon particle surface through their siloxane end groups and crosslink with the SEI film or binder network through organic functional groups, constructing a dual interface structure of "chemical anchoring + flexible buffering." This synergistic mechanism significantly improves the structural stability of the electrode under severe silicon volume expansion, effectively suppressing active material shedding and SEI film rupture and regeneration, thereby achieving high initial coulombic efficiency, low interfacial impedance growth, and excellent long-cycle performance. When the C / A ratio is less than 0.13, it indicates a severe deficiency of silane additives (C) relative to anhydride additives (A). At this point, although the SEI film may be relatively dense, it lacks sufficient molecular bridging, resulting in weak interfacial bonding between silicon particles and the conductive network / current collector. During cycling, silicon is prone to displacement, pulverization, and even detachment from the electrode substrate due to volume changes, leading to "electrical contact failure" and deactivation of active materials. Furthermore, although the SEI film is primarily formed by anhydride additives (A), it lacks the flexibility and self-adaptive capabilities provided by silane additives (C), exhibiting high brittleness and difficulty withstanding repeated stress, resulting in frequent cracking. This leads to increased irreversible lithium consumption, elevated internal resistance, and rapid capacity decay. When the C / A ratio exceeds 4.5, it indicates an excess of silane additives (C) and a relative deficiency of anhydride film-forming agents (A). In this case, the SEI film becomes incomplete due to insufficient A participation, with excessive organic components and low inorganic salt content, resulting in decreased ionic conductivity, weakened electron shielding ability, and reduced initial coulombic efficiency. Meanwhile, excessive silane compounds may undergo self-condensation polymerization in the electrolyte, generating insoluble siloxane polymers that deposit on the electrode or separator surface, hindering lithium-ion transport and increasing polarization. Some silanes may also interfere with the reduction behavior of anhydride film-forming agents (A), disrupting the optimized composition of the SEI film. Furthermore, a high C / A ratio is often accompanied by increased electrolyte viscosity and poorer wettability, further deteriorating rate and low-temperature performance.
[0057] This invention addresses the issues of interfacial mechanical strength, structural flexibility, ion transport kinetics, and cathode interfacial compatibility in silicon anodes through ordered reaction priorities and functional coupling among components, representing a key technological breakthrough in this field. The invention discovers that by precisely combining specific structural anhydride compounds (first additive, A), vinylene carbonate compounds (second additive, B), silane compounds (third additive, C), and sulfonate compounds (fourth additive, D), and ensuring their content satisfies a series of precise mathematical relationships with the silicon anode content (X) (0.05≤(A+B+C) / X≤23; 0.05≤D / (B+C)≤2; 0.13≤C / A≤4.5), directional reactions and functional complementarity of the additives at the cathode and anode interfaces can be induced, constructing a gradient and functionalized stable interface.
[0058] In one embodiment, the values A, B, C, D, and X satisfy the following condition: Equation 4: 0.1≤(A+B+C) / X≤10; Equation 5: 0.07≤D / (B+C)≤0.8; Equation 6: 0.17≤C / A≤4.
[0059] This invention ensures a reasonable match between the total amount of functional additives (A+B+C) and the silicon content (X) through Equation 4, avoiding incomplete SEI film due to insufficient additives or side reactions caused by excessive additives. Combined with the optimized C / A ratio in Equation 6, the anhydride film-forming agent (A) and the silane anchoring agent (C) synergistically construct a dense and flexible SEI film, significantly suppressing excessive electrolyte decomposition during the first cycle and significantly improving the first coulombic efficiency, which is significantly better than conventional silicon-based systems. Moreover, Equations 4 and 6 together ensure that silicon particles obtain sufficient interface protection and mechanical support during repeated lithiation / delithiation processes. The reasonable (A+B+C) / X ratio ensures that the unit silicon surface receives sufficient but not excessive additive coverage, effectively mitigating failure mechanisms such as pulverization and peeling. Equation 5 limits D / (B+C) to the range of 0.07–0.8, ensuring that the amount of the fourth additive (D) is matched with the functional components of the negative electrode. This allows for the formation of a stable CEI film on the positive electrode surface under high voltage, inhibiting electrolyte oxidation and transition metal dissolution. It also prevents excessive fourth additive (D) from causing negative electrode side reactions or increased electrolyte impedance, and prevents insufficient fourth additive (D) from leading to positive electrode degradation and cross-contamination. As a result, the full cell exhibits excellent high-temperature storage performance, high voltage cycle stability, and low gas production rate in the high-nickel ternary / silicon-carbon system. Furthermore, because the three equations collectively suppress the formation of excessively thick, high-resistivity SEI / CEI films and avoid the formation of insoluble polymer precipitation, the electrolyte maintains high ionic conductivity and good electrode wettability.
[0060] In summary, by simultaneously satisfying the synergistic constraints of Equations 4, 5, and 6, this invention achieves an organic unity of high energy density, long cycle life, high safety, and excellent dynamic performance in silicon-based lithium-ion batteries, providing a scientifically sound and practical technical solution for the industrial application of next-generation high-energy-density power batteries and energy storage systems.
[0061] In one embodiment, the anhydride compound is selected from one or more of succinic anhydride, maleic anhydride, and glutaric anhydride.
[0062] Using one or more of succinic anhydride, maleic anhydride, and glutaric anhydride as the first additive can not only efficiently construct a high-performance SEI interface, but also take into account electrochemical performance, safety, and cost-effectiveness, making it an ideal choice for achieving stable operation of high-energy-density silicon-based lithium-ion batteries.
[0063] In one embodiment, the carbonate compound is selected from one or more of vinylene carbonate and fluoroethylene carbonate.
[0064] Using vinylene carbonate (VC) and / or fluoroethylene carbonate (FEC) as the second additive can not only efficiently construct a high-performance SEI interface, but also take into account high initial efficiency, long cycle life, low gas production and good processability. It is one of the core technical elements supporting the stable, safe and long-life operation of the silicon-based high-energy-density lithium-ion battery of this invention.
[0065] In one embodiment, the silane compound is selected from one or more of tetravinylsilane and vinyltris(trimethylsiloxy)silane.
[0066] Using tetravinylsilane and / or vinyltris(trimethylsiloxy)silane as the third additive can not only significantly improve the structural stability and interfacial reversibility of silicon-based anodes through chemical anchoring and flexible film formation mechanisms, but also synergistically construct high-performance SEI with other functional additives in the system. This is an important technical support for realizing high-energy-density and long-life silicon-based lithium-ion batteries.
[0067] In one embodiment, the sulfonate compound is selected from one or more of 1,3-propanesulfonate lactone and 1,3-propenesulfonate lactone.
[0068] The selection of 1,3-propanesulfonyl lactone and / or 1,3-propenesulfonyl lactone as the fourth additive can not only efficiently construct a highly stable CEI film and improve the compatibility of high-voltage positive electrode, but also synergize with the negative electrode interface system to significantly improve the cycle life, high-temperature performance and safety reliability of the battery. It is one of the key components supporting the high-energy-density silicon-based lithium-ion battery of this invention to achieve high-performance and high-safety operation.
[0069] In one embodiment, the device further includes a positive electrode sheet, which includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material, which includes one or more of lithium transition metal oxides, lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, and lithium vanadium phosphate.
[0070] By selecting one or more of the aforementioned transition metal lithium oxides, lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, or lithium vanadium phosphate as the positive electrode active material, not only can their respective advantages in energy density, safety, lifespan, or cost be fully utilized, but they can also be highly synergistic with the silicon-based anode and multifunctional composite electrolyte system (containing four types of additives, A / B / C / D) of this invention to achieve comprehensive performance optimization of high-energy-density, high-safety, and long-life lithium-ion batteries, and have broad prospects for industrial application.
[0071] In this application, there is no particular limitation on the type of positive electrode current collector; it can be any known material suitable for use as a positive electrode current collector. In one embodiment, the positive electrode current collector includes metallic materials such as aluminum, stainless steel, magnesium plating, titanium, and tantalum, as well as carbon materials such as carbon cloth and carbon paper. In one embodiment, the positive electrode current collector is a metallic material.
[0072] In some embodiments, the positive electrode active material layer further includes a positive electrode conductive agent and a positive electrode binder.
[0073] In some embodiments, the type of positive conductive agent mentioned in this invention is not limited, and any known conductive agent can be used.
[0074] In some embodiments, the positive electrode conductive agent mentioned in this invention includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.
[0075] In one embodiment, the type of positive electrode binder mentioned in this invention is not limited, and any known positive electrode binder can be used.
[0076] In some embodiments, the positive electrode binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, and nitrocellulose.
[0077] In some embodiments, the lithium-ion battery may include an outer packaging that can be used to encapsulate the electrode assembly and electrolyte described above.
[0078] In one embodiment, the chemical formula of the transition metal lithium oxide is Li. 1+x Ni y Co z M (1-y-z)O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.
[0079] Using the aforementioned transition metal lithium oxides as positive electrode active materials has the advantages of high specific capacity, high operating voltage, and structural stability. It can be matched with high-capacity silicon-based negative electrodes to jointly achieve high energy density of the battery.
[0080] In one embodiment, another aspect of the present invention provides an electrical device including the battery described above.
[0081] Specifically, the aforementioned electrical devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
[0082] The present invention will be further illustrated by the following examples.
[0083] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Materials not specified in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.
[0084] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.
[0085] In the following embodiments, the reagents, materials and instruments used, unless otherwise specified, are commercially available or can be obtained through synthesis methods known in the art.
[0086] Table 1. Design of battery components for Examples 1-35 and Comparative Examples 1-5; Table 2. Electrolyte composition design for Examples 2 and 36-40 and Comparative Examples 6-9; Example 1 This embodiment illustrates the lithium-ion battery disclosed in this invention, and includes the following operational steps: Preparation of positive electrode sheet Lithium cobalt oxide doped with magnesium, acetylene black (SuperP) as the positive electrode active material, and polyvinylidene fluoride (PVDF) binder are mixed evenly at a mass ratio of 97:1.5:1.5 and then uniformly dispersed with 1-methyl-2-pyrrolidone (NMP) to form a uniform positive electrode slurry. The mixed slurry is coated on both sides of an aluminum foil current collector, and then baked, rolled, and cut into sheets to obtain the positive electrode sheet.
[0087] Preparation of negative electrode sheet Artificial graphite, silicon, acetylene black (Super P), thickener CMC, and SBR binder for the negative electrode were mixed evenly in a mass ratio of 74:20:2:1.2:2.8 and then evenly dispersed with deionized water to form a uniform negative electrode slurry. The mixed slurry was coated on both sides of a copper foil current collector, and then baked, rolled, and cut into sheets to obtain the negative electrode sheet. The mass content of silicon in the negative electrode active layer is shown in Table 1 for the X value.
[0088] Preparation of electrolyte a. Mix ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a mass ratio of 3:7, remove water using a molecular sieve, set aside, and add 1M LiPF6 and mix thoroughly. b. Add the first additive, the second additive, the third additive and the fourth additive (the types and amounts of the first additive, the second additive, the third additive and the fourth additive are shown in Table 1 and Table 2) to the colorless and transparent liquid obtained in step a to obtain the electrolyte.
[0089] Manufacturing of lithium-ion batteries The prepared positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator in the middle of the positive and negative electrode sheets. After winding and welding the tabs, a bare cell is obtained. The bare cell is placed in an aluminum-plastic film for liquid injection, encapsulation, and high-temperature curing at 60°C for 8 hours to obtain a lithium-ion battery.
[0090] Examples 2-40 Examples 2-35 illustrate the lithium-ion battery disclosed in this invention, including most of the operations in Example 2, except that: In Examples 2-35, the mass percentages of the first additive (A / %), the second additive (B / %), the third additive (C / %), the fourth additive (D / %), the silicon material content in the negative electrode active material (X / %), the values of (A+B+C) / X, D / (B+C), and C / A are all referenced in Table 1.
[0091] Examples 36-40 illustrate the lithium-ion battery disclosed in this invention, including most of the operations in Example 2, except that: The types of the first, second, third, and fourth additives in Examples 36-40 are all referenced in Table 2.
[0092] Comparative Examples 1-9 Comparative Examples 1-5 are used to illustrate the lithium-ion battery disclosed in this invention, including most of the operations in Example 2, with the following differences: The percentage of the first additive (A / %), the percentage of the second additive (B / %), the percentage of the third additive (C / %), the percentage of the fourth additive (D / %), the percentage of silicon material in the negative electrode active material (X / %), the values of (A+B+C) / X, D / (B+C), and C / A in Comparative Examples 1-5 are all referenced in Table 1.
[0093] Comparative Examples 6-9 are used to illustrate the lithium-ion battery disclosed in this invention, including most of the operations in Example 2, except that: The types of the first, second, third, and fourth additives in Comparative Examples 6-9 are all referenced in Table 2.
[0094] Performance testing The following performance tests were performed on Examples 1-40 and Comparative Examples 1-9 prepared above: Thermal shock test The lithium-ion batteries prepared in the above embodiments and comparative examples were charged at 25°C at a rate of 1C to the cutoff voltage and a cutoff current of 0.025C. They were then transferred to an oven and heated to 150°C at a rate of 5°C / min and kept constant for 60 minutes. The batteries were considered to have passed the test if they did not catch fire or explode. The number of battery cells tested was 20.
[0095] 45℃ Cyclic Performance Test The lithium-ion batteries prepared in the above embodiments and comparative examples were charged and discharged at 45°C at a rate of 1C / 1C within the charge and discharge cutoff voltage range. The discharge capacity of the first cycle was recorded as C1, and the discharge capacity of the Nth cycle was recorded as C2. The capacity of the Nth cycle was divided by the capacity of the first cycle to obtain the cycle capacity retention rate R2 = C2 / C1. The number of cycles of the lithium-ion battery when the cycle capacity retention rate R2 was 70% was recorded.
[0096] 60℃ Storage Performance Test The lithium-ion batteries prepared in the above embodiments and comparative examples were charged at 25°C at a rate of 1C to the cutoff voltage, with a cutoff current of 0.025C. After standing for 5 minutes, the thickness H1 of the lithium-ion battery was measured. Then, the batteries were stored at 60°C for 60 days, and the thickness H2 of the lithium-ion battery was measured after the storage period.
[0097] Thickness expansion rate = [(H2-H1) / H1]×100%.
[0098] The test results are shown in Table 3.
[0099] Table 3 Battery performance test results of Examples 1-40 and Comparative Examples 1-10 Comparing Example 2 and Comparative Example 1, it can be seen that when the electrolyte uses the first additive, the second additive, the third additive, and the fourth additive, and silicon material is present in the negative electrode active material, it has good thermal shock performance, a high number of cycles at high temperatures, and a low thickness expansion rate. When the electrolyte does not contain the first additive, the second additive, and the third additive, and silicon material is present in the negative electrode active material, it has poor thermal shock performance, a low number of cycles at high temperatures, and a high thickness expansion rate.
[0100] Comparing Example 2 and Comparative Example 2, it can be seen that when the first additive is used in this invention, it has good thermal shock performance, a high number of cycles and a low thickness expansion rate at high temperatures; when the first additive is not present, the SEI layer is unstable, and the thermal shock performance and high temperature cycling performance are poor.
[0101] Comparing Example 2 and Comparative Example 3, it can be seen that when the second additive is used in this invention, it has good thermal shock performance, a high number of cycles and a low thickness expansion rate at high temperatures; when the second additive is not present, the SEI has no elastic layer and its high-temperature cycling performance is poor.
[0102] Comparing Example 2 and Comparative Example 4, it can be seen that when the present invention uses the third additive, it has good thermal shock performance, a high number of cycles and a low thickness expansion rate at high temperatures; when the third additive is not present, the SEI ion conductivity is poor and the battery has a high thickness expansion rate after being stored at 60°C for 35 days.
[0103] Comparing Example 2 and Comparative Example 5, it can be seen that when the present invention uses the fourth additive, it has good thermal shock performance, high cycle count and low thickness expansion rate at high temperature; when the fourth additive is absent, there is no positive electrode protection and the battery has poor thermal shock performance.
[0104] Comparing Examples 2, 36-37 and Comparative Example 6, it can be seen that when the first additive of the present invention is an acid anhydride compound, the battery has good thermal shock performance, a high number of cycles and a low thickness expansion rate at high temperatures; when the first additive is ethylene sulfate, a stable SEI film cannot be formed, resulting in poor overall performance.
[0105] Comparing Examples 2, 38 and 7, it can be seen that when the second additive of the present invention is a carbonate compound, the battery has good thermal shock performance, a high number of cycles and a low thickness expansion rate at high temperatures; when the second additive is propylene carbonate, an elastic SEI film cannot be formed, and the thermal shock and storage performance are both poor.
[0106] Comparing Examples 2, 39 and 8, it can be seen that when the third additive of the present invention is a silane compound, the battery has good thermal shock performance, a high number of cycles and a low thickness expansion rate at high temperatures; when the third additive is ethylene, a siloxane network cannot be formed, resulting in poor overall performance.
[0107] Comparing Examples 2, 40 and 9, it can be seen that when the fourth additive of the present invention is a sulfonate compound, the battery has good thermal shock performance, a high number of cycles and a low thickness expansion rate at high temperatures; when the fourth additive is MMDS, an effective CEI film cannot be formed, and the storage performance and cycle performance are poor at high temperatures.
[0108] Comparing Examples 1-5, it can be seen that when the first additive accounts for 0.5%-5% of the mass percentage of the electrolyte, the battery has good thermal shock performance, a high number of cycles, and a low thickness expansion rate at high temperatures; when the first additive accounts for less than 0.5% of the mass percentage of the electrolyte, the SEI film is unstable, and the storage performance and cycle performance are poor at high temperatures; when the first additive accounts for more than 5% of the mass percentage of the electrolyte, the SEI film is too thick, the impedance is high, and the cycle performance deteriorates.
[0109] Comparing Examples 2 and 6-10, it can be seen that when the second additive accounts for 0.5%-20% of the electrolyte by mass, the battery has good thermal shock performance, a high number of cycles, and a low thickness expansion rate at high temperatures. When the second additive accounts for less than 0.5% of the electrolyte by mass, the insufficient elasticity of the SEI film leads to poor cycle performance at high temperatures. When the second additive accounts for more than 20% of the electrolyte by mass, both thermal shock performance and high-temperature storage performance are poor.
[0110] Comparing Examples 2 and 11-15, it can be seen that when the third additive accounts for 0.5%-5% of the mass percentage of the electrolyte, the battery has good thermal shock performance, a high cycle count, and a low thickness expansion rate at high temperatures; when the third additive accounts for less than 0.5% of the mass percentage of the electrolyte, the battery has poor ionic conductivity, resulting in a high storage expansion rate; when the third additive accounts for more than 5% of the mass percentage of the electrolyte, the SEI film has poor stability and the thermal shock performance deteriorates slightly.
[0111] Comparing Examples 2 and 16-20, it can be seen that when the fourth additive accounts for 0.5%-5% of the mass percentage of the electrolyte, the battery has good thermal shock performance, with a high number of cycles and a low thickness expansion rate at high temperatures; when the fourth additive accounts for less than 0.5% of the mass percentage of the electrolyte, the positive electrode protection is insufficient and the thermal shock performance is poor; when the fourth additive accounts for more than 5% of the mass percentage of the electrolyte, the positive electrode CEI film is too thick, and the high-temperature cycle performance of the battery deteriorates.
[0112] Comparing Examples 2 and 21-23, it can be seen that when the mass content of silicon particles in the negative electrode active material layer is 1%-100%, the battery has good thermal shock performance, a high cycle number, and a low thickness expansion rate at high temperatures.
[0113] Comparing Examples 2, 21, and 23-27, it can be seen that when the value of (A+B+C) / X is in the range of 0.05-23, especially when the value of (A+B+C) / X is in the range of 0.1-10, the battery exhibits good thermal shock performance, with a high cycle life and low thickness expansion rate at high temperatures. When the value of (A+B+C) / X is less than 0.05, insufficient SEI resources lead to poor high-temperature storage and cycle performance; when the value of (A+B+C) / X is greater than 23, excessive additives result in high battery impedance and poor high-temperature cycle performance.
[0114] Comparing Examples 2, 6, 16, and 28-31, it can be seen that when the value of D / (B+C) is in the range of 0.05-2, especially when the value of D / (B+C) is in the range of 0.07-0.8, the battery has good thermal shock performance, exhibiting a high number of cycles and a low thickness expansion rate at high temperatures. When the value of D / (B+C) is less than 0.05, the positive electrode protection is insufficient, resulting in poor thermal shock performance; when the value of D / (B+C) is greater than 2, the positive electrode protection is excessive, leading to poor high-temperature cycle performance.
[0115] Comparing Examples 1, 28, and 32-35, it can be seen that when the C / A value is in the range of 0.13-4.5, especially when the C / A value is in the range of 0.17-4, the battery has good thermal shock performance, a high number of cycles at high temperatures, and a low thickness expansion rate. When the C / A value is less than 0.13, the ionic conductivity is poor, the battery's high-temperature storage performance is poor, and the expansion rate is high. When the C / A value is greater than 4.5, the EI stability is poor, and the battery's thermal shock performance and high-temperature cycling performance are poor.
[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A battery, characterized in that, include A negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, the negative electrode active material comprising a negative electrode active material comprising silicon particles; An electrolyte comprising a first additive, a second additive, a third additive, and a fourth additive, wherein the first additive comprises an acid anhydride compound, the second additive comprises a carbonate compound, the third additive comprises a silane compound, and the fourth additive comprises a sulfonate compound.
2. The battery according to claim 1, characterized in that, The mass content X of silicon particles in the negative electrode active material layer is expressed as a percentage, and the value of X ranges from 1 to 100.
3. The battery according to claim 2, characterized in that, Let the total mass of the electrolyte be denoted as 100%. The mass percentage of the first additive in the electrolyte is denoted as A, with the unit being %, and the value of A ranges from 0.5 to 5. The mass percentage of the second additive in the electrolyte is denoted as B, with the unit being %, and the value of B ranges from 0.5 to 20. The mass percentage of the third additive in the electrolyte is denoted as C, with the unit being %, and the value of C ranges from 0.5 to 5. The mass percentage of the fourth additive in the electrolyte is denoted as D, with the unit being %, and the value of D ranges from 0.5 to 5.
4. The battery according to claim 3, characterized in that, The values of A, B, C, D, and X satisfy the following condition: Equation 1: 0.05 ≤ (A+B+C) / X ≤ 23; Equation 2: 0.05≤D / (B+C)≤2; Equation 3: 0.13≤C / A≤4.
5.
5. The battery according to claim 4, characterized in that, The values of A, B, C, D, and X satisfy the following condition: Equation 1: 0.1≤(A+B+C) / X≤10; Equation 2: 0.07≤D / (B+C)≤0.8; Equation 3: 0.17≤C / A≤4.
6. The battery according to claim 1, characterized in that, The acid anhydride compound is selected from one or more of succinic anhydride, maleic anhydride, and glutaric anhydride.
7. The battery according to claim 1, characterized in that, The carbonate compound is selected from one or more of vinylene carbonate and fluoroethylene carbonate.
8. The battery according to claim 1, characterized in that, The silane compound is selected from one or more of tetravinylsilane and vinyltris(trimethylsiloxy)silane.
9. The battery according to claim 1, characterized in that, The sulfonate compound is selected from one or more of 1,3-propanesulfonate lactone and 1,3-propenesulfonate lactone.
10. The battery according to claim 1, characterized in that, It also includes a positive electrode sheet, which includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material, which includes one or more of lithium transition metal oxides, lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, and lithium vanadium phosphate.
11. The battery according to claim 10, characterized in that, The chemical formula of the transition metal lithium oxide is Li 1+ x Ni y Co z M (1-y-z) O2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1; M is selected from one or more of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo, and Zr.
12. An electrical appliance, characterized in that, Includes the battery described in any one of claims 1 to 11.