A lithium ion battery, a power consuming device

Abstract

In order to improve the thermal runaway of the battery, and meanwhile make the battery have better low-temperature and high-temperature electrical performance, the application provides a lithium ion battery and a power utilization device, which comprise a negative electrode, a positive electrode, a separator and an electrolyte, the negative electrode comprises a negative electrode active material layer, the negative electrode active material layer comprises a negative electrode active material; the positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material and a solid-state electrolyte, and the positive electrode active material layer comprises titanium elements; the electrolyte comprises a solvent and an additive, the solvent comprises fluorosulfonamide compounds and linear fluorocarbon carbonate compounds; and the additive comprises fluorosulfonamide compounds containing cyano groups and lithium salt additives.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a lithium-ion battery and an electrical device. Background Technology

[0002] Lithium-ion batteries, as the mainstream rechargeable battery technology, are crucial for electric vehicles and large-scale energy storage due to their energy density, cycle life, and safety. However, batteries are prone to thermal runaway under thermal abuse conditions, and sluggish ion transport kinetics at low temperatures lead to a sharp decline in performance. Furthermore, long-term cycling at high temperatures exacerbates interfacial side reactions, causing accelerated capacity decay. Existing improvement measures include the following methods: 1. Introducing fluoroethylene carbonate or linear fluorocarbonate into the electrolyte to improve high-voltage stability or low-temperature performance, respectively; however, the extensive use of linear fluorocarbonate sacrifices thermal safety. 2. Introducing a solid electrolyte into the positive electrode active material layer improves thermal stability but easily increases interfacial impedance.

[0003] Therefore, there is an urgent need for a battery that improves thermal runaway while also having good low-temperature and high-temperature electrical performance. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium-ion battery and an electrical device to improve battery thermal runaway and to give the battery better low-temperature and high-temperature electrical performance.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a lithium-ion battery, comprising a negative electrode, a positive electrode, a separator, and an electrolyte, wherein the negative electrode comprises a negative electrode active material layer, the negative electrode active material layer comprising a negative electrode active material; the positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprising a positive electrode active material and a solid electrolyte, the positive electrode active material layer comprising titanium. The electrolyte includes a solvent and additives. The solvent includes fluorosulfonamide compounds and linear fluorocarbonate compounds. The additives include cyano-containing fluorosulfonamide compounds and lithium salt additives. Wherein, the fluorosulfonamide compound in the electrolyte has a mass content A% of 1%~40%, the linear fluorocarbonate compound in the electrolyte has a mass content B% of 1%~40%, the cyano-containing fluorosulfonamide compound in the electrolyte has a mass content C% of 0.2%~4%, and the lithium salt additive in the electrolyte has a mass content D% of 0.1%~3%; The mass content H% of the solid electrolyte in the positive electrode active material layer is 0.3%~5%, and the content X of titanium in the positive electrode active material layer is 50ppm~2000ppm; The porosity P% of the diaphragm is 20%~70%; The specific surface area W m of the negative electrode active material 2 / g is 1m 2 / g~30m 2 / g, the compaction density Y g / cm³ of the negative electrode active material 3 1g / cm 3 ~2.2g / cm 3 ; The lithium-ion battery satisfies the following relationship: Equation 1: 2.33 ≤ (A+C+D)×1000 / X ≤ 396.00; Equation 2: 0.40≤(C+D)×100 / (B+W+P)≤13.09; Equation 3: 0.03 ≤ (C+H) / B ≤ 3.95; Equation 4: 11.90≤P / Y≤54.17.

[0006] Optionally, the lithium-ion battery satisfies at least one of the following relationships: Equation 5: 2.50 ≤ (A+C+D)×1000 / X ≤ 330.00; Equation 6: 0.76≤(C+D)×100 / (B+W+P)≤8.48; Equation 7: 0.07≤(C+H) / B≤3.00; Equation 8: 12.50≤P / Y≤45.00.

[0007] Optionally, the lithium-ion battery satisfies at least one of the following conditions: The mass content (A%) of the fluorosulfonamide compound in the electrolyte is 10% to 30%; The linear fluorocarbonate compound has a mass content (B%) of 10% to 30% in the electrolyte. The cyano-containing fluorosulfonamide compound has a mass content (C%) of 0.5% to 3% in the electrolyte; The lithium salt additive has a mass content (D%) of 0.3% to 1.5% in the electrolyte; The mass content (H%) of the solid electrolyte in the positive electrode active material layer is 1%~3%; The titanium content X in the positive electrode active material layer is 300ppm~1500ppm; The porosity P% of the diaphragm is 20%~50%; The specific surface area W m of the negative electrode active material 2 / g is 4m 2 / g~20m 2 / g; The compaction density Y of the negative electrode active material is 1 g / cm³ 3 1.4 g / cm 3 ~2g / cm 3 .

[0008] Optionally, the fluorosulfonamide compound includes at least one of 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, dimethylaminosulfonyl fluoride, and N,N-diethylaminosulfonyl fluoride.

[0009] Optionally, the linear fluorocarbonate compound includes at least one of methyl trifluoroethylene carbonate, di(2,2,2-trifluoroethyl) carbonate, ethyl (2,2,2-trifluoroethyl) carbonate, and bis(fluoromethyl) carbonate.

[0010] Optionally, the cyano-containing fluorosulfonamide compound includes at least one of compounds 1-1 to 1-5; .

[0011] Optionally, the lithium salt additive includes at least one of LiFSI, LiTFSI, LiBOB, LiODFB, LiPO2F2, LiBF4, and lithium fluorosulfonate.

[0012] Optionally, the mass content of the positive electrode active material in the positive electrode active material layer is 80% to 99%.

[0013] Optionally, the solid electrolyte is selected from at least one of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconate (LLZO), lithium aluminum germanium phosphate (LAGP), and lithium lanthanum titanate (LLTO); The positive electrode active material includes a transition metal lithium oxide, the chemical formula of which 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; where M is selected from one or more of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Nb, and Mo; The negative electrode active material includes one of graphite negative electrode, silicon-carbon composite negative electrode, or lithium metal negative electrode.

[0014] Secondly, the present invention provides an electrical device including a lithium-ion battery as described above.

[0015] In this invention, the total amount of interfacial film-forming components is quantitatively correlated with the titanium doping of the cathode using Equation 1: Titanium doping utilizes high-valence Ti... 4+To stabilize the positive electrode crystal structure and suppress oxygen release, fluorosulfonamide compounds, cyano-containing fluorosulfonamide compounds, and lithium salt additives jointly provide interface protection. Formula 2 ensures that the total amount of additives matches the battery's ion transport capacity and reaction interface scale: the cyano-containing fluorosulfonamide compounds complex transition metal ions with the lithium salt additives to form a dense interface film rich in LiF and sulfur and nitrogen components. Linear fluorocarbonate compounds ensure high ionic conductivity at low temperatures. The specific surface area of ​​the negative electrode and the porosity of the separator determine the reaction interface and ion channel capacity. This ratio ensures that the additives are neither weakened by relative deficiency in thermal safety and cycle stability, nor generate high-resistance byproducts due to relative excess, which would lead to a sharp decline in performance at zero degrees Celsius. Equation 3 enables control over the strength of the positive electrode's chemical-physical dual protection and solvent content: the chemical CEI film formed by cyano-containing fluorosulfonamide compounds, together with the physical thermal barrier and mechanical support provided by the solid electrolyte, resists the oxidative decomposition and corrosion of linear fluorocarbonate compounds under high pressure and high temperature. Equation 4 coordinates the ion channels of the separator with the electron conduction and solid-phase diffusion capabilities of the negative electrode: the membrane porosity determines the liquid-phase lithium-ion transport efficiency, and the compaction density of the negative electrode active material affects the interparticle electron contact and the lithium-ion solid-phase diffusion path. This ratio couples the ion transport capability with the electron conductance and solid-phase diffusion kinetics, avoiding the risk of increased low-temperature polarization or lithium plating due to ion transport limitations, and also avoiding reduced utilization of active materials due to a loose electron network. When all parameter ranges and four relationships are satisfied simultaneously, the risk of thermal runaway under thermal abuse conditions is significantly reduced, ion transport is efficient and polarization is controllable during low-temperature cycling, effectively suppressing interfacial side reactions during high-temperature long-term cycling and slowing down significant capacity decay. Detailed Implementation

[0016] To make the technical problems solved, the technical solutions, and the 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.

[0017] An embodiment of the present invention provides a lithium-ion battery, including a negative electrode, a positive electrode, a separator, and an electrolyte. The negative electrode includes a negative electrode active material layer, which includes a negative electrode active material. The positive electrode includes a positive electrode active material layer, which includes a positive electrode active material and a solid electrolyte. The positive electrode active material layer includes titanium. The electrolyte includes a solvent and additives. The solvent includes fluorosulfonamide compounds and linear fluorocarbonate compounds. The additives include cyano-containing fluorosulfonamide compounds and lithium salt additives. Wherein, the fluorosulfonamide compound in the electrolyte has a mass content A% of 1%~40%, the linear fluorocarbonate compound in the electrolyte has a mass content B% of 1%~40%, the cyano-containing fluorosulfonamide compound in the electrolyte has a mass content C% of 0.2%~4%, and the lithium salt additive in the electrolyte has a mass content D% of 0.1%~3%; The mass content H% of the solid electrolyte in the positive electrode active material layer is 0.3%~5%, and the content X of titanium in the positive electrode active material layer is 50ppm~2000ppm; The porosity P% of the diaphragm is 20%~70%; The specific surface area W m of the negative electrode active material 2 / g is 1m 2 / g~30m 2 / g, the compaction density Y g / cm³ of the negative electrode active material 3 1g / cm 3 ~2.2g / cm 3 ; The lithium-ion battery satisfies the following relationship: Equation 1: 2.33 ≤ (A+C+D)×1000 / X ≤ 396.00; Equation 2: 0.40≤(C+D)×100 / (B+W+P)≤13.09; Equation 3: 0.03 ≤ (C+H) / B ≤ 3.95; Equation 4: 11.90≤P / Y≤54.17.

[0018] Specifically, the mass content of the fluorosulfonamide compound in the electrolyte includes, but is not limited to, 1%, 5%, 10%, 20%, 30%, and 40%. The linear fluorocarbonate compound in the electrolyte contains, but is not limited to, 1%, 5%, 10%, 20%, 30%, and 40% by mass. The mass content of the cyano-containing fluorosulfonamide compound in the electrolyte includes, but is not limited to, 0.2%, 0.5%, 1%, 2%, 3%, and 4%. The lithium salt additive in the electrolyte has a mass content including, but not limited to, 0.1%, 0.3%, 0.5%, 1%, 2%, and 3%. The mass content of the solid electrolyte in the positive electrode active material layer includes, but is not limited to, 0.3%, 0.5%, 1%, 2%, 3%, and 5%. The content of titanium in the positive electrode active material layer includes, but is not limited to, 50ppm, 150ppm, 500ppm, 1000ppm, 1500ppm, and 2000ppm. The porosity of the diaphragm includes, but is not limited to, 20%, 30%, 40%, 50%, 60%, and 70%. The specific surface area of ​​the negative electrode active material includes, but is not limited to, 1m². 2 / g、4m 2 / g、8m 2 / g, 15m 2 / g、25m 2 / g、30m 2 / g; The compaction density of the negative electrode active material includes, but is not limited to, 1 g / cm³. 3 1.4g / cm 3 1.6g / cm 3 1.8g / cm 3 2g / cm 3 2.2g / cm 3 .

[0019] Equation 1 of this application quantitatively correlates the total amount of interfacial film components with the cathode titanium doping: titanium doping utilizes high-valence Ti 4+To stabilize the positive electrode crystal structure and suppress oxygen release, fluorosulfonamide compounds, cyano-containing fluorosulfonamide compounds, and lithium salt additives jointly provide interface protection. Formula 2 ensures that the total amount of additives matches the battery's ion transport capacity and reaction interface scale: the cyano-containing fluorosulfonamide compounds complex transition metal ions with the lithium salt additives to form a dense interface film rich in LiF and sulfur and nitrogen components. Linear fluorocarbonate compounds ensure high ionic conductivity at low temperatures. The specific surface area of ​​the negative electrode and the porosity of the separator determine the reaction interface and ion channel capacity. This ratio ensures that the additives are neither weakened by relative deficiency in thermal safety and cycle stability, nor generate high-resistance byproducts due to relative excess, which would lead to a sharp decline in performance at zero degrees Celsius. Equation 3 enables control over the strength of the positive electrode's chemical-physical dual protection and solvent content: the chemical CEI film formed by cyano-containing fluorosulfonamide compounds, together with the physical thermal barrier and mechanical support provided by the solid electrolyte, resists the oxidative decomposition and corrosion of linear fluorocarbonate compounds under high pressure and high temperature; Equation 4 coordinates the ion channel of the separator with the electron conduction and solid-phase diffusion capabilities of the negative electrode: the membrane porosity determines the liquid-phase lithium-ion transport efficiency, and the compaction density of the negative electrode active material affects the interparticle electron contact and the lithium-ion solid-phase diffusion path. This ratio couples the ion transport capability with the electron conductivity and solid-phase diffusion kinetics, avoiding the risk of increased low-temperature polarization or lithium plating due to ion transport shortcomings, and also avoiding the reduction of active material utilization due to a loose electron network. When all parameter ranges and four relationships are satisfied simultaneously, the risk of thermal runaway of the battery under thermal abuse conditions is significantly reduced, ion transport is efficient and polarization is controllable during low-temperature cycling, effectively suppressing interfacial side reactions during high-temperature long-term cycling and slowing down significant capacity decay; This invention constructs an interrelated and mutually restrictive constraint network from four dimensions through the above-mentioned relationship: "resource matching between interface modification and cathode bulk stability", "coordination between the amount of functional additives and the system transport / reaction capacity", "counterbalancing between cathode protection strength and risky solvent erosion", and "balance between macroscopic ion channels and electrode structural characteristics". Satisfying any one of the relationship or parameter range may lead to a one-sided enhancement of performance, while causing unacceptable losses in other key dimensions.

[0020] In some embodiments, the lithium-ion battery satisfies at least one of the following relationships: Equation 5: 2.50 ≤ (A+C+D)×1000 / X ≤ 330.00; Equation 6: 0.76≤(C+D)×100 / (B+W+P)≤8.48; Equation 7: 0.07≤(C+H) / B≤3.00; Equation 8: 12.50≤P / Y≤45.00.

[0021] Specifically, the above relationship ensures a balance between the supply and demand of interfacial film-forming resources and the stability of the cathode body, avoiding slight protection deficiencies or slight impedance increases that may occur near the boundary value. If the ratio (A+C+D)×10000 / X is too low, for cathodes with high bulk stability obtained through titanium doping, there will be insufficient interfacial protection resources, making it impossible to form an effective CEI / SEI to suppress side reactions, leading to accelerated cycle decay and interfacial instability during thermal shock. If the ratio is too high, it indicates excessive interfacial film-forming reaction, especially when the titanium doping amount is low and the cathode body stability is weak. An excessively thick interfacial film will drastically increase the impedance of lithium-ion cross-interfacial transport, seriously damaging the rate performance and low-temperature (0°C) performance of the battery, and may lead to excessive consumption of active lithium. The additives defined by Formula 6 are more closely coordinated with the transport reaction capacity, allowing the interface modification effects of cyano-containing fluorosulfonamide compounds and lithium salt additives to be fully utilized without triggering unnecessary side reactions. If the ratio (C+D)×1000 / (B+W+P) is too low, the additive concentration is seriously insufficient relative to the vast transport and reaction space, resulting in a weak interface modification effect and deterioration of the battery's long-term cycle stability and thermal safety. If the ratio is too high, the excessive additive will continuously decompose in the large system composed of linear fluorocarbonate compounds, the specific surface area of ​​the negative electrode active material, and the porosity of the separator, which will rapidly generate a large number of high-resistivity interface byproducts. This will not only accelerate the loss of active lithium but also significantly increase the bulk and interface impedance, leading to a rapid increase in battery internal resistance and a rapid decline in capacity. Especially at low temperatures of 0°C, the performance will deteriorate sharply. Formula 7 optimizes the protection strength of the positive electrode side and the offsetting relationship with the solvent, ensuring thermal shock safety while maximizing the low-temperature kinetic advantages brought by linear fluorinated carbonate compounds. If the (C+H) / B ratio is too low, the positive electrode protection is weak and cannot effectively resist the continuous erosion of the oxidation decomposition products of linear fluorinated carbonate compounds, leading to damage to the surface structure of the positive electrode material, accelerated dissolution of transition metals, significantly deterioration of thermal shock safety, and accelerated high-temperature cycle decay. If the ratio is too high, it means that the CEI is too thick or the solid electrolyte is too full, which will seriously hinder the transport of lithium ions between positive electrode particles and at the solid-liquid interface, causing severe kinetic lag, thereby significantly damaging the battery's 0℃ low-temperature performance, rate performance and energy efficiency. The macroscopic coupling between the ion channels and electrode structure defined by Equation 8 is more reasonable, the charge transport efficiency of the whole cell reaches the optimal level, and the overall performance balance of the battery is further improved. When the P / Y ratio is too low, ion transport becomes the bottleneck of battery dynamics, the internal polarization of the battery increases sharply, resulting in a serious decline in low-temperature discharge performance at 0℃. During high-rate charging, lithium plating on the negative electrode is easily induced due to uneven lithium ion insertion, which seriously threatens safety. When the ratio is too high (such as too high porosity or too low compaction density), the electron conduction network is imperfect, the electrode structure is loose, the utilization rate of active materials is low, the volumetric energy density decreases significantly, and the stability of the electrode structure deteriorates during cycling.

[0022] In some embodiments, the lithium-ion battery satisfies at least one of the following conditions: The mass content (A%) of the fluorosulfonamide compound in the electrolyte is 10% to 30%; The linear fluorocarbonate compound has a mass content (B%) of 10% to 30% in the electrolyte. The cyano-containing fluorosulfonamide compound has a mass content (C%) of 0.5% to 3% in the electrolyte; The lithium salt additive has a mass content (D%) of 0.3% to 1.5% in the electrolyte; The mass content (H%) of the solid electrolyte in the positive electrode active material layer is 1%~3%; The titanium content X in the positive electrode active material layer is 300ppm~1500ppm; The porosity P% of the diaphragm is 20%~50%; The specific surface area W m of the negative electrode active material 2 / g is 4m 2 / g~20m 2 / g; The compaction density Y of the negative electrode active material is 1 g / cm³ 3 1.4 g / cm 3 ~2g / cm 3 .

[0023] The fluorosulfonamide compound in the electrolyte contains, but is not limited to, 10%, 15%, 20%, 25%, and 30% by mass. The linear fluorocarbonate compound in the electrolyte has a mass content including, but not limited to, 10%, 15%, 20%, 25%, and 30%. The cyano-containing fluorosulfonamide compound in the electrolyte contains, but is not limited to, 0.5%, 1%, 2%, and 3% by mass. The lithium salt additive in the electrolyte has a mass content including, but not limited to, 0.3%, 0.5%, 0.7%, 1%, and 1.5%. The mass content of the solid electrolyte in the positive electrode active material layer includes, but is not limited to, 1%, 1.3%, 2%, 2.6%, and 3%. The content of titanium in the positive electrode active material layer includes, but is not limited to, 300ppm, 380ppm, 500ppm, 900ppm, and 1500ppm. The porosity of the diaphragm includes, but is not limited to, 20%, 30%, 40%, and 50%. The specific surface area of ​​the negative electrode active material includes, but is not limited to, 4m². 2 / g、7m 2 / g, 10m 2 / g, 15m 2 / g、20m 2 / g; The compaction density of the negative electrode active material includes, but is not limited to, 1.4 g / cm³. 3 1.5g / cm 3 1.6g / cm 3 1.7g / cm 3 1.8g / cm 3 2g / cm 3 .

[0024] Specifically, within this preferred range, fluorosulfonamide compounds can fully contribute to film formation and high-pressure oxidation stability, and the interfacial impedance is controllable. When the content of fluorosulfonamide compounds is too low, their contribution to interfacial and high-pressure stability is insufficient. When the content is too high, excessive decomposition increases interfacial impedance and generates by-products, slightly impairing thermal shock safety. The low-temperature and high-temperature cycling performance changes from initial improvement to later deterioration. Linear fluorinated carbonate compounds significantly improve low-temperature ionic conductivity. However, when the content of linear fluorinated carbonate compounds is too low, the improvement effect on low-temperature performance is insufficient. When the content is too high, the disadvantage of relatively poor chemical and electrochemical stability becomes prominent. Under high pressure and high temperature, they are prone to oxidative decomposition, producing gas and aggravating side reactions, which significantly damages the thermal stability (thermal shock) of the battery. At the same time, the accumulation of decomposition products at high temperature leads to a slight deterioration in cycle performance. Cyano-containing fluorosulfonamides form a dense, thermally stable interfacial film at a moderate concentration without causing excessive impedance. When the content is too low, the interfacial protection and complexation effect is weak. When the content is too high, the resulting interfacial film is too thick and has high impedance, which seriously hinders ion transport at low temperatures, leading to direct deterioration of the 0°C cycle. In the later stages of the high-temperature cycle, it also deteriorates due to excessive interfacial impedance and the accumulation of side reactions. Lithium salt additives synergistically optimize the composition of the dual-interface film without consuming excessive active lithium. When the content is too low, the interface modification effect is insufficient; when the content is too high, excessive decomposition will increase the thickness of the interface film and the proportion of inorganic components, increase impedance, consume active lithium, and lead to performance deterioration in the later stages of cycling at 0℃ and 45℃. Solid electrolytes provide physical and thermal enhancement while avoiding ion conduction blockage. When their content is too low, the physical protection and thermal improvement effects are insufficient. When their content is too high, they will significantly increase the ion transport impedance inside the electrode and may affect the dispersion of active materials and the electronic conduction network, directly leading to low-temperature performance deterioration. The performance in the later stages of high-temperature cycling is also limited by ion transport kinetics. Titanium effectively stabilizes the cathode lattice without compromising capacity. However, when its content is too low, the stabilization effect is insufficient. When its content is too high, it may block lithium-ion diffusion channels or introduce too much electrochemical inert component, leading to a decrease in the ionic conductivity and capacity of the material, thereby causing the cycle performance to deteriorate instead of improve. The porosity of the diaphragm balances the electrolyte retention and mechanical strength. Too low a porosity will restrict ion conduction, increase polarization, and impair high and low temperature performance; too high a porosity will weaken the mechanical properties and puncture resistance of the diaphragm, making it more prone to internal short circuits during thermal shock, thus deteriorating safety. At the same time, excessive porosity may exacerbate side reactions and reduce performance in the later stages of cycling. The specific surface area of ​​the negative electrode provides sufficient reaction sites without causing excessive SEI growth. When the specific surface area is too high, the total amount of SEI formation will increase proportionally, consuming more active lithium and electrolyte, forming a thicker and more unstable interface layer, increasing impedance and heat generation, and slightly deteriorating thermal stability. At high temperatures, the side reactions are accelerated, leading to deterioration in the later stages of cycling. When the specific surface area is too low, the reaction interface is insufficient, affecting performance. The compaction density of the negative electrode active material ensures the integrity of the electronic network and does not block the lithium-ion channels. However, excessive compaction will severely compress the electrode pores, block the lithium-ion transport channels, and lead to uneven local current density, increased polarization, and significantly deterioration of low-temperature performance. At the same time, the tight structure may restrict electrolyte penetration and increase mechanical stress. If the compaction density is too low, the electrode structure will be loose, the electronic conductivity will be poor, and the volumetric energy density will be low.

[0025] In some embodiments, the fluorosulfonamide compound includes at least one of 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, dimethylaminosulfonyl fluoride, and N,N-diethylaminosulfonyl fluoride.

[0026] Specifically, the fluorine-containing properties and high oxidation stability of these compounds cause them to decompose at the electrode interface to generate a stable interface layer rich in LiF. Their molecular size and polarity ensure good miscibility with other solvent components, effectively improving the high-pressure oxidation stability of the electrolyte without significantly increasing viscosity.

[0027] In some embodiments, the linear fluorocarbonate compound includes at least one of methyl trifluoroethylene carbonate (CAS No.: 156783-95-8), bis(2,2,2-trifluoroethyl) carbonate, ethyl (2,2,2-trifluoroethyl) carbonate, and bis(fluoromethyl) carbonate.

[0028] Specifically, these linear fluorocarbonates have low viscosity and high low-temperature fluidity, which significantly reduces the low-temperature viscosity of the electrolyte and improves the ionic conductivity. Their fluorinated structure has higher oxidation stability than ordinary linear carbonates, which ensures performance at zero degrees Celsius without excessively sacrificing thermal safety.

[0029] In some embodiments, the cyano-containing fluorosulfonamide compound includes at least one of compounds 1-1 to 1-5; .

[0030] Specifically, these compounds contain both cyano and fluorosulfonamide groups. The cyano group can strongly adsorb or complex transition metal ions on the positive electrode surface, inhibiting their dissolution. The fluorosulfonamide part decomposes at the positive and negative electrodes to form a highly thermally stable interface film containing LiF, sulfur, and nitrogen components, which significantly improves the thermal shock safety of the battery. The complexation effect of the cyano group works synergistically with titanium doping to stabilize the positive electrode interface. The content of cyano-containing fluorosulfonamide compounds can be precisely controlled to adjust the interface modification intensity.

[0031] In some embodiments, the lithium salt additive includes at least one of LiFSI, LiTFSI, LiBOB, LiODFB, LiPO2F2, LiBF4, and lithium fluorosulfonate.

[0032] Specifically, these additives form a stable CEI component during positive electrode oxidation, contribute LiF and sulfur oxides to optimize SEI during negative electrode reduction, form a synergistic film-forming effect with cyano-containing fluorosulfonamide compounds, and LiFSI and LiTFSI can contribute high concentrations of fluorine and sulfur, LiBOB and LiODFB can contribute boron-oxygen crosslinking structures to enhance interfacial film toughness, and LiPO2F2 and LiBF4 can contribute phosphorus and fluorine components to improve ion conduction, ensuring the contribution of lithium salt additives to interfacial modification and transport matching in the formula.

[0033] In some embodiments, the mass content of the positive electrode active material in the positive electrode active material layer is 80% to 99%.

[0034] Specifically, the mass content of the positive electrode active material in the positive electrode active material layer includes, but is not limited to, 80%, 83%, 85%, 89%, 94%, 97%, and 99%. As the main component for lithium-ion insertion and extraction, the content of the positive electrode active material, together with the content of the solid electrolyte and the titanium element, determines the energy density and ion-electron transport balance of the positive electrode. Appropriately adjusting the content of the positive electrode active material can match the relationship, so that the chemical-physical dual protection strength and the charge transport kinetics of the whole battery can be optimally matched.

[0035] In some embodiments, the solid electrolyte is selected from at least one of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconate (LLZO), lithium aluminum germanium phosphate (LAGP), and lithium lanthanum titanate (LLTO); The positive electrode active material includes a transition metal lithium oxide, the chemical formula of which 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; where M is selected from one or more of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Nb, and Mo; The negative electrode active material includes one of graphite negative electrode, silicon-carbon composite negative electrode, or lithium metal negative electrode.

[0036] Specifically, these solid electrolytes possess high ionic conductivity and thermal stability, acting as a physical thermal barrier to suppress thermal runaway. The positive electrode active material system is compatible with titanium doping and solid electrolytes, enhancing structural stability under high voltage and optimizing the scale of interfacial reactions and transport kinetics. The ionic conductivity of the solid electrolyte itself may provide additional transport paths, and together with the chemical CEI film, it constitutes a "chemical + physical" enhanced positive electrode protection system to resist the risk of interfacial erosion that may be caused by the oxidative decomposition of linear fluorinated carbonates.

[0037] In some embodiments, the type of positive current collector is not particularly limited, and it can be any material known to be suitable for use as a positive current collector.

[0038] In some embodiments, the positive current collector includes metallic materials such as aluminum, stainless steel, aluminum plating, titanium, and tantalum, as well as carbon materials such as carbon cloth and carbon paper.

[0039] In some embodiments, the positive current collector is a metallic material.

[0040] In some embodiments, the positive electrode active material layer further includes a positive electrode conductive agent and a positive electrode binder.

[0041] In some embodiments, there is no limitation on the type of positive conductive agent, and any known conductive agent can be used.

[0042] In some embodiments, the positive electrode conductive agent includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.

[0043] In some embodiments, there is no limitation on the type of positive electrode binder, and any known positive electrode binder may be used.

[0044] In some embodiments, the positive electrode binder includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR).

[0045] In some embodiments, the negative electrode active material layer includes a negative electrode active substance, which includes one of graphite negative electrode, silicon-carbon composite negative electrode, or lithium metal negative electrode.

[0046] In some embodiments, there are no particular limitations on the negative current collector, as long as it can achieve the purpose of this application. For example, it can be copper foil, copper alloy foil, aluminum foil, stainless steel foil, titanium foil, aluminum foam, copper foam, or composite current collector, etc.

[0047] In some embodiments, the negative current collector comprises copper foil.

[0048] 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 and a negative electrode binder.

[0049] In some embodiments, the negative electrode conductive agent includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, and graphene.

[0050] In some embodiments, the negative electrode binder includes at least one of styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), and polyacrylic acid (PAA).

[0051] 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.

[0052] 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 (such as polyethylene PE, polypropylene PP), aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc.

[0053] In some embodiments, the electrolyte further includes lithium salts, including but not limited to lithium hexafluorophosphate, which have the effect of providing a stable lithium ion source and ensuring the basic conductivity of the electrolyte.

[0054] In some embodiments, the electrolyte further includes a base solvent, which includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, methyl propionate, and γ-butyrolactone.

[0055] Specifically, the aforementioned basic solvents are selected primarily to dissolve fluorosulfonamide compounds, linear fluorocarbonate compounds, cyano-containing fluorosulfonamide compounds, lithium salt additives, and lithium salts, and to provide a basic solvation environment.

[0056] 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.

[0057] In some embodiments, the present invention also provides an electrical device including a lithium-ion battery as described above.

[0058] Specifically, the battery of the present invention has the ability to pass thermal shock safety tests, maintain high efficiency in charge-discharge cycles at zero degrees Celsius, and have a lifespan characteristic with significantly reduced capacity decay rate during long cycles at forty-five degrees Celsius, thus meeting the comprehensive requirements of power system safety, all-weather adaptability and durability for extreme environment application scenarios.

[0059] The present invention will be further illustrated by the following examples.

[0060] 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.

[0061] Furthermore, it should be understood that one or more method steps mentioned in this invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these expressly mentioned steps, unless otherwise stated. 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.

[0062] Example 1 The preparation method of lithium-ion batteries includes the following steps: Preparation of positive electrode sheet The positive electrode active material (LiNi doped with titanium) 0.8 Co0.1 Mn 0.1 O2 (titanium content shown in Table 1), positive electrode conductive agent acetylene black (Super P), polyvinylidene fluoride (PVDF) binder, and solid electrolyte (LATP mass percentage of 2%) are mixed evenly at a mass ratio of 94.5:2:1.5:2 and then evenly dispersed with 1-methyl-2-pyrrolidone (NMP) to form a uniform positive electrode slurry. The mixed slurry is coated on both sides of the aluminum foil current collector, and then baked, rolled, and cut into sheets to obtain the positive electrode sheet.

[0063] Preparation of negative electrode sheet Artificial graphite (negative electrode active material), acetylene black (Super P) (negative electrode conductive agent), sodium carboxymethyl cellulose (CMC) (thickener), and styrene-butadiene rubber (SBR) (negative electrode binder) were mixed evenly at a mass ratio of 96:1.5:1.0:1.5, and then uniformly dispersed with deionized water to form a homogeneous negative electrode slurry. The slurry was then coated onto both sides of a copper foil current collector, and subsequently baked and rolled to a predetermined compaction density of 1.6 g / cm³. 3 After cutting, the negative electrode sheet is obtained, and the specific surface area of ​​the negative electrode active material is 6m². 2 / g.

[0064] Preparation of electrolyte a. In an argon-filled glove box, ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a mass ratio of 3:7 as the base solvent, and 1M LiPF6 lithium salt is added and mixed evenly. b. Add fluorosulfonamide compound (1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, mass percentage A%), linear fluorocarbonate compound (methyltrifluoroethylene carbonate (CAS No.: 156783-95-8), mass percentage B%), cyano-containing fluorosulfonamide compound (compound 1-1, mass percentage C%), and lithium salt additive (LiFSI, mass percentage D%) to the solution obtained in step a, stir evenly, and obtain the electrolyte. The amount of each component is shown in Table 1.

[0065] Manufacturing of lithium-ion batteries The prepared positive electrode sheet, separator (porosity 45%, ceramic coating facing the positive electrode), and negative electrode sheet are stacked in sequence, and then wound and welded to obtain a bare cell. The bare cell is placed in an aluminum-plastic film, and the above-mentioned electrolyte is injected. After encapsulation, standing, formation, and shaping, a lithium-ion soft pack battery is obtained.

[0066] Example 2-45 Examples 2-45 are mostly the same as the preparation steps in Example 1, with the differences shown in Tables 1 and 2.

[0067] Examples 46-63 Example 46 is similar to Example 1 in most of the preparation steps, except that the fluorosulfonamide compound is dimethylaminosulfonyl fluoride.

[0068] Example 47 is similar to Example 1 in most of the preparation steps, except that the fluorosulfonamide compound is N,N-diethylaminosulfonyl fluoride.

[0069] Example 48 is similar to Example 1 in most of the preparation steps, except that the linear fluorocarbonate compound is bis(2,2,2-trifluoroethyl) carbonate.

[0070] Example 49 is similar to Example 1 in most of the preparation steps, except that the linear fluorocarbonate compound is (2,2,2-trifluoroethyl) ethyl carbonate.

[0071] Example 50 is similar to Example 1 in most of the preparation steps, except that the linear fluorocarbonate compound is a bis(fluoromethyl)carbonate.

[0072] Example 51 is similar to Example 1 in most of the preparation steps, except that the cyano-containing fluorosulfonamide compound is compound 1-2.

[0073] Example 52 is similar to Example 1 in most of the preparation steps, except that the cyano-containing fluorosulfonamide compounds are compounds 1-3.

[0074] Example 53 is similar to Example 1 in most of the preparation steps, except that the cyano-containing fluorosulfonamide compounds are compounds 1-4.

[0075] Example 54 is similar to Example 1 in most of the preparation steps, except that the cyano-containing fluorosulfonamide compounds are compounds 1-5.

[0076] Example 55 is similar to Example 1 in most of the preparation steps, except that the lithium salt additive is LiTFSI.

[0077] Example 56 is similar to Example 1 in most of the preparation steps, except that the lithium salt additive is LiBOB.

[0078] Example 57 is similar to Example 1 in most of the preparation steps, except that the lithium salt additive is LiODFB.

[0079] Example 58 is similar to Example 1 in most of the preparation steps, except that the lithium salt additive is LiPO2F2.

[0080] Example 59 is similar to Example 1 in most of the preparation steps, except that the lithium salt additive is LiBF4.

[0081] Example 60 is similar to Example 1 in most of the preparation steps, except that the lithium salt additive is lithium fluorosulfonate.

[0082] Example 61 is similar to Example 1 in most of the preparation steps, except that the solid electrolyte type is LLZO.

[0083] Example 62 is similar to Example 1 in most of the preparation steps, except that the solid electrolyte type is LAGP.

[0084] Example 63 is similar to Example 1 in most of the preparation steps, except that the solid electrolyte type is LLTO.

[0085] Examples 64-71 Examples 64-71 are largely the same as those in Example 1, with the differences shown in Tables 1 and 2.

[0086] Table 1. Preparation parameters of lithium-ion batteries in the examples Continued from Table 1 Table 2. Preparation parameters of lithium-ion batteries in the examples Continued from Table 2 Comparative Examples 1-31 Comparative Examples 1-31 are largely the same as those in Example 1, with the differences shown in Tables 3 and 4.

[0087] Comparative Examples 32-36 Comparative Example 32 is similar to Example 1 in most of the preparation steps, except that FEC is used instead of fluorosulfonamide compounds.

[0088] Comparative Example 33 is similar to Example 1 in most of the preparation steps, except that DMC is used instead of linear fluorocarbonate compounds.

[0089] Comparative Example 34 is similar to Example 1 in most of its preparation steps, except that HTCN is used instead of cyano-containing fluorosulfonamide compounds.

[0090] Comparative Example 35 is similar to Example 1 in most of the preparation steps, except that PS is used instead of lithium salt additives.

[0091] Comparative Example 36 is similar to Example 1 in most of the preparation steps, except that ceramic is used instead of solid electrolyte.

[0092] Comparative Examples 37-62 Comparative Examples 37-62 are largely the same as those in Example 1, with the differences shown in Tables 3 and 4.

[0093] Table 3 Comparative Lithium-ion Battery Fabrication Parameters Continued from Table 3 Table 4 Comparative Lithium-ion Battery Fabrication Parameters Continued from Table 4 Performance testing (1) Thermal shock performance test The lithium-ion batteries (100 units) of each embodiment and comparative example were charged to full capacity at 25°C with constant current and constant voltage of 1C. The fully charged batteries were placed in an oven and heated to 130°C at a rate of 5°C / min, and kept at this temperature for 1 hour. The number of batteries that thermally runaway (fire, explosion) during the test was recorded to characterize thermal shock safety by the number of batteries. The more batteries that pass the test, the better the safety.

[0094] (2) 0℃ Cyclic Performance Test The lithium-ion batteries of each embodiment and comparative example were charged to full capacity at 0°C with constant current and constant voltage at 0.5C, and then discharged to cutoff voltage with constant current at 1C. The charging and discharging steps were repeated, and the number of cycles that the battery could withstand when the capacity retention rate decayed to 80% was recorded. The higher the number of cycles, the better the low temperature cycling performance.

[0095] (3) Cyclic performance test at 45℃ The lithium-ion batteries of each embodiment and comparative example were charged to full capacity at 45°C with constant current and constant voltage at 1C, and then discharged to the cutoff voltage with constant current at 1C. The charging and discharging steps were repeated, and the number of cycles that the battery could withstand when the capacity retention rate decayed to 80% was recorded. The higher the number of cycles, the better the high temperature cycling performance.

[0096] Test Results The performance test results of the examples and comparative examples are shown in Table 5.

[0097] Table 5 Performance test results of the examples and comparative examples Continued from Table 5 Continued from Table 5 Continued from Table 5 Based on the test results above, it can be seen that in Comparative Examples 1-6, due to the complete absence of one or more of the following in the electrolyte: fluorosulfonamide compounds, linear fluorocarbonate compounds, cyano-containing fluorosulfonamide compounds, or lithium salt additives, Formulas 1 to 3 cannot be satisfied. The absence of fluorosulfonamide compounds and cyano-containing fluorosulfonamide compounds prevents the formation of a dense interfacial film (CEI / SEI) rich in LiF and containing sulfur and nitrogen components on the positive and negative electrode surfaces. The cyano group cannot complex the transition metal ions dissolved from the positive electrode. The absence of lithium salt additives further weakens the ion conductivity and structural toughness of the interfacial film. The absence of linear fluorocarbonate compounds leads to a severe decrease in low-temperature ionic conductivity. Simultaneously, although the positive electrode active material layer contains titanium, there is no interfacial protection synergy, and the high-valence state Ti doped with titanium... 4+ It cannot effectively suppress oxygen release and structural degradation. Therefore, the interfacial side reactions are severe and the thermal stability is extremely poor. This is manifested in the fact that only 4-8 particles can pass through the thermal shock test, and the number of cycles at 0℃ and 45℃ that retain 80% of the capacity is less than 235 cycles, resulting in extremely poor overall performance.

[0098] In Comparative Examples 7-30, the absence of at least one key component (such as fluorosulfonamides, linear fluorocarbonates, cyano-containing fluorosulfonamides, lithium salt additives, or solid electrolytes) renders at least one ratio in the four equations invalid or significantly deviates from the range. For example, in Comparative Example 31, the absence of a solid electrolyte results in a lack of physical thermal barrier and mechanical support on the positive electrode side, preventing the formation of a dual "chemical + physical" protection with the chemical CEI film. Linear fluorocarbonates are more prone to oxidation and decomposition under high pressure and high temperature, leading to a decrease in thermal shock performance (7 particles) and premature degradation during high-temperature cycling. In Comparative Examples 7-9, the absence of cyano-containing fluorosulfonamides results in the loss of cyano complexation, increased dissolution of transition metal ions, a lack of nitrogen-containing components in the interfacial film, insufficient thermal stability, and a thermal shock pass rate mostly below 9 particles, with cycle times generally below 260 cycles. Although Comparative Examples 11 and 14 partially satisfy the equation values, the absence of other components still leads to significant performance degradation.

[0099] Comparative Examples 31-36 used solvents, additives, or solid electrolytes not found in this invention (such as non-fluorinated sulfonamides, nonlinear fluorinated carbonates, non-cyano-containing fluorinated sulfonamides, non-lithium salt additives, or non-specific solid electrolytes), and these could not satisfy the relevant relationships. Non-fluorinated sulfonamide compounds could not generate sufficient LiF at the interface and exhibited insufficient oxidative stability; nonlinear fluorinated carbonate compounds had high viscosity and low ionic conductivity at low temperatures; and non-cyano-containing fluorinated sulfonamide compounds lacked cyano complexing ability, resulting in poor interfacial film thermal stability. Therefore, only 5-7 particles passed through the thermal shock test, and the number of cycles was less than 235, verifying the synergistic necessity of the specific functional group structure of this invention.

[0100] In Comparative Examples 37-40, the mass content of fluorosulfonamide compounds or linear fluorocarbonate compounds exceeded the scope of the claims (A should be 1-40, B should be 1-40). When A=0.1, the interfacial film-forming components were insufficient, the LiF content was low, the CEI / SEI was incomplete, and the high-pressure oxidation stability was poor, with only 7 thermal shock cycles. When A=50, excessive decomposition increased interfacial impedance and produced byproducts, hindering lithium-ion cross-interface transport, and the 0℃ cycle time decreased to 219 cycles. When B=0.1, the electrolyte had high low-temperature viscosity, low ionic conductivity, and increased low-temperature polarization, with only 210 cycles at 0℃. When B=50, its poor oxidation stability became prominent, and it easily decomposed and produced gas under high pressure and high temperature, corroding the positive electrode interface, with only 190 cycles at 45℃ and only 4 thermal shock cycles.

[0101] In Comparative Examples 41-46, when the mass content of cyano-containing fluorosulfonamide compounds or lithium salt additives exceeded the range of 0.2%~4% or 0.1%~3%, at C=5, the excess cyano-containing fluorosulfonamides decomposed to form an excessively thick and high-resistivity interfacial film, which severely hindered ion transport at low temperatures, resulting in only 164 cycles at 0℃; at D=5, the excess lithium salt additives consumed active lithium and increased the film thickness, resulting in no more than 186 cycles at both 0℃ and 45℃; at H=8, the solid electrolyte excessively filled the positive electrode active material layer, blocking the ion conduction path and affecting the electron network, resulting in only 126 cycles at 0℃.

[0102] In Comparative Examples 47-50, the membrane porosity or titanium content exceeded the range (P should be 20-70, X should be 50-2000). When P=10, the membrane porosity was too low, resulting in extremely low liquid-phase lithium-ion transport efficiency, increased low-temperature polarization, and only 203 cycles at 0℃. When P=80, the membrane mechanical properties decreased, making it prone to internal short circuits during thermal shock, and the excessive porosity exacerbated side reactions, resulting in only 6 thermal shock cycles. When X=10, the titanium doping content was too low, failing to effectively stabilize the cathode crystal structure, exacerbating oxygen release, and resulting in only 6 thermal shock cycles. When X=3000, excessive titanium blocked the lithium-ion diffusion channels, reducing the bulk ionic conductivity of the material, and only 211 cycles at 45℃.

[0103] In Comparative Examples 51-54, the specific surface area or compaction density of the negative electrode active material exceeds 1-30 m². 2 / g or 1~2.2 g / cm 3 Within the specified range, when W=0.5, the reaction interface is insufficient, resulting in fewer lithium-ion insertion sites and a cycle life of only 164 cycles at 0℃. When W=50, excessive SEI growth consumes active lithium and electrolyte, increasing impedance and heat generation, resulting in only 4 thermal shocks. When Y=0.5, the electron network is loose, leading to low utilization of active material and only 4 thermal shocks. When Y=2.5, the electrode pores are severely compressed, blocking lithium-ion transport channels and causing uneven local current density, resulting in only 3 thermal shocks.

[0104] In Comparative Examples 55-62, although each individual parameter is within the scope of the claims, all four relationships are not satisfied simultaneously: Comparative Example 55 (Equation 1: 0.85 < 2.33): The total amount of interfacial film-forming components is too low relative to the titanium doping amount. For titanium doping to obtain a cathode with high bulk stability, the interfacial protection resources are insufficient, and it is impossible to form an effective CEI / SEI to suppress side reactions, resulting in accelerated cycle decay (only 310 / 324 cycles at 0℃ / 45℃). Comparative Example 56 (Equation 1 = 940 > 396): The ratio is too high, and the excessively thick interfacial film drastically increases the lithium-ion transinterfacial transport impedance, severely impairing low-temperature performance (only 312 / 323 cycles at 0℃ / 45℃). Comparative Example 57 (Equation 2 = 0.50 < 0.76, Equation 3 = 0.055 < 0.07): The total amount of additives is insufficient relative to the ion transport capacity (B+W+P), resulting in a weak interface modification effect. Simultaneously, the cathode protection strength (C+H) is too low compared to linear fluorinated carbonate compounds, failing to withstand the oxidative decomposition and corrosion of linear fluorinated carbonates, leading to only 9 thermal shock cycles and a cycle life of only 313 cycles at 45℃. Comparative Example 58 (Equation 2 = 31.82 > 13.09, Equation 3 = 6 > 3.95): Excessive additives continuously decompose within the large reaction system, generating high-resistance byproducts, accelerating the loss of active lithium, resulting in only 299 cycles at 0℃. Furthermore, the excessively thick CEI combined with an excessive amount of solid electrolyte severely hinders lithium-ion transport, leading to performance degradation at 0℃. Comparative Example 60 (Equation 3 = 9 > 3.95): Excessive chemical and physical protection of the cathode, excessively thick CEI, and an excessive amount of solid electrolyte result in kinetic stagnation, leading to only 298 cycles at 0℃. Comparative Example 61 (Equation 4 = 9.09 < 11.90): Ion transport becomes a bottleneck, polarization increases, leading to a significant decrease in low-temperature discharge at 0°C, easy lithium plating during high-rate charging, and only 294 cycles at 0°C. Comparative Example 62 (Equation 4 = 70 > 54.17): The electron conduction network is imperfect, the electrode structure is loose, and the utilization rate of active materials is low, resulting in only 307 cycles at 45°C. These results demonstrate that the four relationships constitute an interrelated and mutually restrictive constraint network, none of which can be omitted.

[0105] In Example 1, all values ​​are within the preferred range, and the relationship satisfies the preferred range. It passed the thermal shock test with 17 particles, and underwent 425 cycles at 0°C and 428 cycles at 45°C, demonstrating excellent overall performance.

[0106] In Examples 2-5, the mass content of fluorosulfonamide compounds increased from 10% to 40%. When A=10~30 (Examples 2-4), the appropriate amount of fluorosulfonamide compounds contributed sufficient LiF film formation while maintaining oxidation stability and controllable interfacial impedance. The thermal shock was 15-16 particles, and the cycle time at 0°C was 426-437 cycles, and at 45°C it was 445-459 cycles. When A=40 (Example 5), the excessive fluorosulfonamide decomposed, increasing interfacial impedance and producing byproducts, which slightly impaired thermal shock. The thermal shock was reduced to 15 particles, and the cycle time at 0°C and 45°C was reduced to 411 cycles and 438 cycles, respectively. This indicates that an excessively high A value can slightly impair thermal safety and low-temperature performance.

[0107] In Examples 6-10, the mass content of linear fluorocarbonate compounds increased from 1% to 40%. When B=10~17 (Examples 7-8), the overall performance was the best (422-439 cycles at 0℃, 454-463 cycles at 45℃). When B=1 (Example 6), there was too little linear fluorocarbonate, resulting in high low-temperature viscosity of the electrolyte, insufficient ionic conductivity, and prominent low-temperature polarization. The cycle time at 0℃ was only 411 cycles, but its oxidative stability was relatively good, reaching 467 cycles at 45℃. When B=30~40 (Examples 9-10), the thermal shock decreased to 13-14 cycles, the cycle time at 0℃ increased to 444-449 cycles, but the cycle time at 45℃ decreased to 428-444 cycles. This indicates that too low a B value sacrifices low-temperature kinetics, while too high a B value weakens thermal stability and high-temperature cycling.

[0108] In Examples 11-15, the mass content of cyano-containing fluorosulfonamide compounds increased from 0.2% to 4%. When C=0.5~1.3 (Examples 12-13), the thermal shock count was 15-17, the cycle count at 0°C was 426-443, and the cycle count at 45°C was 442-454. When C=0.2 (Example 11), the cyano complexation effect was weak, the interfacial film contained less nitrogen components, and the thermal stability was insufficient. The thermal shock count was only 14, and the cycle counts at 0°C and 45°C decreased slightly. When C=3~4 (Examples 14-15), the thermal shock count increased to 17-18, but the interfacial film was too thick and had high impedance, which seriously hindered low-temperature ion transport. The cycle count at 0°C decreased to 386-409, and the cycle count at 45°C decreased to 427-441. This indicates that the high C value led to an excessively thick interfacial film and deteriorated low-temperature performance.

[0109] In Examples 16-20, the mass content of lithium salt additives increased from 0.1% to 3%. When D=0.3~1.2 (Examples 17-18), the thermal shock count was 15-16, and the cycling performance was good. When D=0.1 (Example 16), the thermal shock count was 15, but the interface modification effect was insufficient, and the cycling performance was slightly lower. When D=1.5~3 (Examples 19-20), the excessive additives consumed active lithium, the proportion of inorganic components in the interface film was too high, the impedance increased, and the thermal shock count increased to 17, but the cycling performance at 0°C dropped to 407-422 cycles, and the cycling performance at 45°C dropped to 421-437 cycles. This indicates that an excessively high D value will consume too much active lithium and increase the impedance.

[0110] In Examples 21-25, the mass content of the solid electrolyte increased from 0.3% to 5%. When H=1~2 (Examples 22-23), the physical barrier and the chemical CEI membrane worked together to resist the oxidative decomposition of linear fluorinated carbonates, with 15-16 thermal shocks and excellent cycling performance. When H=0.3 (Example 21), the physical thermal barrier and mechanical support provided by the solid electrolyte were insufficient, with only 14 thermal shocks. When H=2.5~5 (Examples 24-25), the excess solid electrolyte blocked ion transport between positive electrode particles, resulting in kinetic stagnation and a decrease in cycling at 0°C to 386-401 cycles, indicating that excessive H would block ion transport.

[0111] In Examples 26-30, the membrane porosity increased from 20% to 70%. When P=30~50 (Examples 27-28), the ion channel and electrode structure were well matched, balancing the electrolyte retention and mechanical strength. The thermal shock rate was 15-17 cycles, and the cycling was relatively balanced. When P=20 (Example 26), the membrane porosity was low, limiting the liquid-phase lithium-ion transport efficiency. The 419 cycles at 0℃ were slightly lower. When P=60~70 (Examples 29-30), the excessively high porosity weakened the membrane's puncture resistance and heat shrinkage resistance, making it prone to internal short circuits during thermal shock. The thermal shock rate dropped to 12-13 cycles. Furthermore, the large porosity may exacerbate side reactions. The 418-428 cycles at 45℃ dropped, indicating that excessively high P weakens the mechanical strength and exacerbates side reactions.

[0112] In Examples 31-35, the titanium content increased from 50 ppm to 2000 ppm. When X = 300~1125 (Examples 32-33), Ti 4+ A stable positive electrode lattice, in synergy with interface protection, exhibits excellent cycling performance with 15-16 thermal shocks. When X=50 (Example 31), the titanium doping level is too low, failing to effectively suppress oxygen release and crystal structure degradation, resulting in slightly lower cycling performance with 15 thermal shocks. When X=1500~2000 (Examples 34-35), excessive titanium may block lithium-ion diffusion channels or introduce inert components, leading to a decrease in ionic conductivity. Cycling at 0℃ drops to 401-414 cycles, indicating that insufficient titanium leads to insufficient bulk stability, while excessive titanium blocks lithium-ion diffusion.

[0113] In Examples 36-40, the specific surface area of ​​the negative electrode active material ranges from 1 m². 2 / g increased to 30m 2 / g, when W=4~12 (Examples 37-38), the appropriate specific surface area provides sufficient reaction sites, and the total amount of SEI formation is controllable, without consuming excessive active lithium; when W=1 (Example 36), the reaction interface is insufficient, there are few lithium ion insertion sites, and the cycle performance is poor; when W=20~30 (Examples 39-40), the excessively high specific surface area leads to excessive SEI growth, which consumes active lithium and electrolyte, forms a thick and unstable interface layer, increases impedance and heat generation, and reduces thermal shock to 14-15 particles, and the 45°C cycle to 406-414 cycles, indicating that too low W results in insufficient reaction sites, and too high W leads to excessive SEI growth.

[0114] In Examples 41-45, the compaction density of the negative electrode active material ranged from 1 g / cm³. 3 Increased to 2.2 g / cm³ 3 When Y=1.4~1.8 (Examples 42-43), the electronic contact between particles is good, the lithium ion solid-phase diffusion path is moderate, and the overall performance is excellent; when Y=1 (Example 41), the compaction density is too low, the electronic conduction network is loose, the utilization rate of active material is low, and the cycle at 45℃ is only 438 cycles; when Y=2~2.2 (Examples 44-45), the excessive compaction severely compresses the electrode pores, blocks the lithium ion transport channel, the local current density is uneven, the polarization increases, and the cycle at 0℃ drops to 419-427 cycles, indicating that the electronic network is loose when the compaction is too low, and the lithium ion channel is blocked when the compaction is too high.

[0115] Examples 46-63, by changing the specific types of various compounds or the type of solid electrolyte, showed performance similar to that of Example 3, demonstrating that the fluorosulfonamide compounds, linear fluorocarbonate compounds, cyano-containing fluorosulfonamide compounds, lithium salt additives, and solid electrolytes listed in this invention can all effectively construct the above-mentioned four-dimensional constraint network.

[0116] Examples 64-71 are at the boundary values ​​of the relational formulas: Example 64 (Equation 1 = 2.33 lower limit): The interfacial film-forming resources are relatively small compared to the titanium doping amount, resulting in insufficient protection. Only 13 thermal shocks were achieved, and the cycle life was only 381 / 404 cycles. Example 65 (Equation 1 = 396 upper limit): The interfacial film-forming reaction was excessive, and the excessively thick interfacial film drastically increased the lithium-ion transinterfacial transport impedance, impairing rate capability and low-temperature performance. The cycle life was only 383 / 403 cycles at 0℃ / 45℃. Example 66 (Equation 2 = 0.40 lower limit): The total amount of additives was insufficient relative to the ion transport capacity, resulting in weak interfacial modification. Only 12 thermal shocks were achieved, and the cycle life was only 393 cycles at 45℃. Example 67 (Equation 2 = 13.09 upper limit): Excess additives continuously decomposed in the system composed of linear fluorocarbonate, high specific surface area anode, and high porosity separator, generating high-impedance byproducts. The cycle life was only 370 cycles at 0℃ and only 409 cycles at 45℃. Example 68 (Equation 3 = 0.03 lower limit): The chemical and physical protection strength of the positive electrode is too low compared to linear fluorinated carbonate compounds, and it cannot effectively resist the oxidative decomposition of linear fluorinated carbonates. It only cycles for 395 cycles at 45°C. Example 69 (Equation 3 = 3.95 upper limit): The chemical and physical dual protection strength on the positive electrode side is too high. The excessively thick CEI film and the high content of solid electrolyte hinder lithium-ion transport, causing kinetic sluggishness. It only cycles for 369 cycles at 0°C and only 391 cycles at 45°C. Example 70 (Equation 4 = 11.90 lower limit): Ion transport becomes the kinetic bottleneck. Low-temperature polarization is severe. It only cycles for 364 cycles at 0°C. Example 71 (Equation 4 = 54.17 upper limit): High porosity weakens the mechanical properties of the separator. It is prone to internal short circuits during thermal shock (only 13 cells). Low compaction density leads to a loose electron conduction network and low utilization of active materials. It only cycles for 387 cycles at 45°C. The performance of these boundary embodiments is significantly inferior to that of the embodiments within the preferred range, demonstrating that the preferred relation (Equations 5-8) can achieve a better overall balance.

[0117] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A lithium-ion battery, characterized in that, The device includes a negative electrode, a positive electrode, a separator, and an electrolyte. The negative electrode includes a negative electrode active material layer, which includes a negative electrode active material. The positive electrode includes a positive electrode active material layer, which includes a positive electrode active material and a solid electrolyte. The positive electrode active material layer includes titanium. The electrolyte includes a solvent and additives. The solvent includes fluorosulfonamide compounds and linear fluorocarbonate compounds. The additives include cyano-containing fluorosulfonamide compounds and lithium salt additives. Wherein, the fluorosulfonamide compound in the electrolyte has a mass content A% of 1%~40%, the linear fluorocarbonate compound in the electrolyte has a mass content B% of 1%~40%, the cyano-containing fluorosulfonamide compound in the electrolyte has a mass content C% of 0.2%~4%, and the lithium salt additive in the electrolyte has a mass content D% of 0.1%~3%; The mass content H% of the solid electrolyte in the positive electrode active material layer is 0.3%~5%, and the content X of titanium in the positive electrode active material layer is 50ppm~2000ppm; The porosity P% of the diaphragm is 20%~70%; The specific surface area W m of the negative electrode active material 2 / g is 1m 2 / g~30m 2 / g, the compaction density of the negative electrode active material Yg / cm 3 1g / cm 3 ~2.2g / cm 3 ; The lithium-ion battery satisfies the following relationship: Equation 1: 2.33 ≤ (A+C+D)×1000 / X ≤ 396.00; Equation 2: 0.40≤(C+D)×100 / (B+W+P)≤13.09; Equation 3: 0.03 ≤ (C+H) / B ≤ 3.95; Equation 4: 11.90≤P / Y≤54.

17.

2. The lithium-ion battery according to claim 1, characterized in that, The lithium-ion battery satisfies at least one of the following relationships: Equation 5: 2.50 ≤ (A+C+D)×1000 / X ≤ 330.00; Equation 6: 0.76≤(C+D)×100 / (B+W+P)≤8.48; Equation 7: 0.07≤(C+H) / B≤3.00; Equation 8: 12.50≤P / Y≤45.

00.

3. The lithium-ion battery according to claim 1, characterized in that, The lithium-ion battery satisfies at least one of the following conditions: The mass content (A%) of the fluorosulfonamide compound in the electrolyte is 10% to 30%; The linear fluorocarbonate compound in the electrolyte has a mass content (B%) of 10% to 30%; The cyano-containing fluorosulfonamide compound has a mass content (C%) of 0.5% to 3% in the electrolyte; The lithium salt additive has a mass content (D%) of 0.3% to 1.5% in the electrolyte; The mass content (H%) of the solid electrolyte in the positive electrode active material layer is 1%~3%; The titanium content X in the positive electrode active material layer is 300ppm~1500ppm; The porosity P% of the diaphragm is 20%~50%; The specific surface area W m of the negative electrode active material 2 / g is 4m 2 / g~20m 2 / g; The compaction density Y of the negative electrode active material is 1 g / cm³ 3 1.4 g / cm 3 ~2g / cm 3 .

4. The lithium-ion battery according to claim 1, characterized in that, The fluorosulfonamide compounds include at least one of 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, dimethylaminosulfonyl fluoride, and N,N-diethylaminosulfonyl fluoride.

5. The lithium-ion battery according to claim 1, characterized in that, The linear fluorocarbonate compounds include at least one of methyl trifluoroethylene carbonate, di(2,2,2-trifluoroethyl) carbonate, ethyl (2,2,2-trifluoroethyl) carbonate, and bis(fluoromethyl) carbonate.

6. The lithium-ion battery according to claim 1, characterized in that, The cyano-containing fluorosulfonamide compounds include at least one of compounds 1-1 to 1-5; 。 7. The lithium-ion battery according to claim 1, characterized in that, The lithium salt additives include at least one of LiFSI, LiTFSI, LiBOB, LiODFB, LiPO2F2, LiBF4, and lithium fluorosulfonate.

8. The lithium-ion battery according to claim 1, characterized in that, The mass content of the positive electrode active material in the positive electrode active material layer is 80%~99%.

9. The lithium-ion battery according to claim 1, characterized in that, The solid electrolyte is selected from at least one of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconate (LLZO), lithium aluminum germanium phosphate (LAGP), and lithium lanthanum titanate (LLTO). The positive electrode active material includes a transition metal lithium oxide, the chemical formula of which 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; where M is selected from one or more of Mg, Zn, Ga, Ba, Al, Cr, Sn, V, Mn, Sc, Nb, and Mo; The negative electrode active material includes one of graphite negative electrode, silicon-carbon composite negative electrode, or lithium metal negative electrode.

10. An electrical device, characterized in that, Including the lithium-ion battery as described in any one of claims 1 to 9.

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