Wide-temperature-range sodium ion battery

Abstract

The invention discloses a wide-temperature-range sodium-ion battery. Electrolyte additives comprise a first additive A and a second additive B, the first additive A is selected from one or more of cyclic compounds containing sulfonyl oxygen structures; the second additive B is selected from one or more of chain compounds containing sulfonyloxy structures and meets the following formula relation: (a + b) / 0.01 (c * rho) is more than or equal to 1.25 and less than or equal to 130, a is more than or equal to 0.1% and less than or equal to 5%, b is more than or equal to 0.01% and less than or equal to 3%, c is more than or equal to 2m < 2 > / g and less than or equal to 25m < 2 > / g, rho is more than or equal to 0.85 g / cm < 3 > and less than or equal to 1.15 g / cm < 3 >, and a is the mass percent of the first additive A in the electrolyte; b is the mass percentage content of the second additive B in the electrolyte; c is the specific surface area of the cathode material; and rho is the compaction density of the negative plate, so that the problems of poor performance, impedance increase and narrow temperature range at high temperature and low temperature are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a wide temperature range sodium ion battery. Background Art

[0002] Although sodium-ion battery technology is relatively mature and occupies an important market position in the new energy sector, the scarcity, high cost, safety issues, and limitations on lithium resources and battery capacity and cycle life have limited its ability to further expand its application market. In contrast, sodium-ion batteries have the advantages of low raw material costs and a wide range of sources, as well as good rate and low-temperature performance. As a highly promising emerging energy storage technology, sodium-ion batteries have shown huge market potential and broad application prospects in the energy storage field. They have great application potential in large-scale energy storage, electric vehicles, backup power supplies, and other fields, and are expected to contribute to energy transformation and sustainable development.

[0003] Due to Na + The desolvation energy is usually lower than that of Li + , thereby reducing the activation barrier for its participation in electrochemical reactions. In addition, sodium salts are generally more thermally stable than lithium salts. Therefore, sodium-ion batteries have the potential to operate over a wide temperature range. However, in practical applications, the performance of sodium-ion batteries is significantly affected by temperature. In high or low temperature environments, sodium-ion batteries generally have problems such as low energy density, rapid capacity decay, poor cycle stability, gas production, and low safety. This is mainly because at high temperatures, the increased thermal motion of molecules leads to increased solubility in the SEI film. The volume change during the charge and discharge process makes the SEI film more prone to rupture, and the rate of side reactions between the electrolyte and the negative electrode is accelerated, which may lead to battery capacity decay. At low temperatures, the sodium ion transfer rate in the electrolyte is reduced, the sodium ion desolvation process at the electrode-electrolyte interface is hindered, the sodium ion movement in the interface layer is difficult, and the electron and sodium ion transport in the electrode is also restricted. These charge transfer restrictions lead to a decline in the overall performance of the battery. To improve high and low temperature performance, researchers have taken a variety of measures, such as optimizing the electrolyte formula, using solvents or additives with better low temperature performance, and using tetrahydrofuran-induced weak solvating electrolytes to accelerate the desolvation process of sodium ions. However, such electrolytes may have stability issues, which may affect the life and safety of the battery under long-term use or specific conditions. By reducing the surface density of the material, improving the particle size of the electrode material, or surface coating or pre-sodium treatment of the material, the kinetic performance and stability at high and low temperatures can also be improved. However, the selection of these methods and the control of the process are more critical. Improper operation may affect the electrochemical properties of the electrode material, often compromising other properties such as energy density and long cycle time, making it difficult to achieve the optimal balance of comprehensive performance.

[0004] In view of this, it is necessary to develop a wide-temperature range sodium-ion battery that can take into account both high and low temperature performance, reduce the requirements for the use environment, improve the applicability and reliability of the battery, and improve the energy density, interface stability and cycle performance of the battery in a wide temperature range, which has become an urgent need in the current market. Summary of the Invention

[0005] The present invention addresses the problems in the prior art of low battery energy density, poor electrochemical performance, poor cycle performance, and poor stability in extreme high and low temperature application scenarios. The invention discloses a wide-temperature range sodium-ion battery, which improves the applicability and reliability of the battery, balances the coulombic efficiency and cycle performance at high and low temperatures, and solves the problems of poor high and low temperature performance, increased impedance, and narrow temperature range of current sodium-ion batteries.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention first provides a wide temperature range sodium ion battery electrolyte;

[0008] The wide temperature range sodium ion battery electrolyte includes an electrolyte additive;

[0009] The electrolyte additives include a first additive A and a second additive B;

[0010] The first additive A is selected from one or more compounds having a cyclic sulfonyloxy structure and has the following structure:

[0011] Wherein, R1 is selected from oxygen atom, C1-C3 alkylene group; R2 is selected from C1-C3 halogenated or non-halogenated hydrocarbon group,

[0012]

[0013] One of the following;

[0014] R3 is selected from one of a hydrogen atom, a halogen atom, a C1-C3 halogenated or non-halogenated alkyl group, and a C2-C3 halogenated or non-halogenated alkenyl group;

[0015] R4, R5, R6, and R7 are each independently selected from a C1-C3 halogenated or non-halogenated hydrocarbon group and an oxygen atom, and at least one of R4 and R5 is an oxygen atom, and at least one of R6 and R7 is an oxygen atom;

[0016] Preferably, the ring where R1 and R2 are located in the structure of the first additive A is a five-membered ring to a seven-membered ring;

[0017] Specifically, when the ring where R1 and R2 are located in the structure of the first additive A is a five-membered ring, the total number of carbon atoms of R1 and R2 in the five-membered ring is 2;

[0018] When the ring containing R1 and R2 in the structure of the first additive A is a six-membered ring, the total number of carbon atoms of R1 and R2 in the six-membered ring is 3;

[0019] When the ring containing R1 and R2 in the structure of the first additive A is a seven-membered ring, the total number of carbon atoms of R1 and R2 in the seven-membered ring is 4;

[0020] The second additive B is selected from one or more chain compounds containing a sulfonyloxy structure and has the following structure:

[0021]

[0022] wherein R8 is selected from an alkali metal atom, a C1-C6 halogenated or non-halogenated hydrocarbon group, a C1-C6 halogenated or non-halogenated acyl group, a halogenated or non-halogenated sulfonyl group, or a halogenated or non-halogenated silyl group;

[0023] wherein R9 is selected from one of a halogen atom, a C1-C6 halogenated or non-halogenated hydrocarbon group, a C1-C6 halogenated or non-halogenated hydrocarbonoxy group, a C1-C6 halogenated or non-halogenated ester group (R10COO—), and a C1-C6 halogenated or non-halogenated sulfonic acid group (R11SO3—);

[0024] R10 is selected from one of C1 to C5 halogen atoms, halogenated or non-halogenated hydrocarbon groups, and R11 is selected from one of C1 to C6 halogen atoms, halogenated or non-halogenated hydrocarbon groups;

[0025] The amounts of the first additive A and the second additive B in the electrolyte satisfy the following formula: 1.25≤(a+b) / 0.01(c*ρ)≤130, and 0.1%≤a≤5%, 0.01%≤b≤3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3 ≤ρ≤1.15g / cm 3 , where a is the mass percentage of the first additive A in the electrolyte; b is the mass percentage of the second additive B in the electrolyte; c is the specific surface area of ​​the negative electrode material; and ρ is the compaction density of the negative electrode sheet.

[0026] As a further solution, the amounts of the first additive A and the second additive B in the electrolyte further satisfy 5≤(a+b) / 0.01(c*ρ)≤80.

[0027] As a further solution, the c and ρ also satisfy 2≤c / ρ≤10; when the above 0.1%≤a≤5%, 0.01%≤b≤3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3≤ρ≤1.15g / cm 3 , 5≤(a+b) / 0.01(c*ρ)≤80, and 2≤c / ρ≤10, the performance is even better. In this case, the capacity retention rate after 500 cycles at 45℃1C is ≥93.9%, the impedance growth rate after 500 cycles at 45℃1C is ≤7%, the capacity retention rate after 10 cycles at 20℃0.2C is ≥99%, and the average coulombic efficiency after 10 cycles at 20℃0.2C is ≥99.9%.

[0028] As a further preferred embodiment, in the first additive A, R1 is selected from one of an oxygen atom and a C1-C3 alkylene group; R2 is selected from one of a C1-C3 non-halogenated hydrocarbon group, R3 is selected from one of a hydrogen atom, a halogen atom, a C1-C3 non-halogenated alkyl group, a C2-C3 halogenated or non-halogenated alkenyl group.

[0029] As a further preferred example, in the first additive A, R1 is selected from one of an oxygen atom and a C1 alkylene group; R2 is selected from one of a C1-C3 non-halogenated alkylene group, One of them.

[0030] As a further preferred example, the first additive A is selected from one or more of Compounds 1 to 23:

[0031]

[0032]

[0033] As a further preferred embodiment, the first additive A is one or more of Compound 1, Compound 2, Compound 22, Compound 7, and Compound 23.

[0034] As a further preferred embodiment, R8 in the second additive B is selected from one of an alkali metal atom, a C1-C3 halogenated alkyl group, a C1-C3 halogenated ester group, a C1-C3 halogenated sulfonyl group, and a C3-C6 silane group, and R9 is selected from one of a halogen atom, a C1-C3 halogenated hydrocarbon group, and a C1-C3 halogenated hydrocarbonoxy group.

[0035] As a further preferred embodiment, in the second additive B, R8 is selected from an alkali metal atom and a C1-C3 halogenated alkyl group, and R9 is selected from a halogen atom, a C1 halogenated hydrocarbon group, and a C1 halogenated hydrocarbonoxy group.

[0036] The second additive B is selected from one or more of compounds 24 to 48:

[0037]

[0038] As a further preferred embodiment, the second additive B is one or more of compound 24, compound 25, compound 30, compound 34, and compound 35.

[0039] As a further preferred embodiment, the electrolyte additive further includes fluorinated carbonate.

[0040] The fluorocarbonate is selected from one or more of fluoroethylene carbonate, trifluoromethylethylene carbonate, and bisfluoroethylene carbonate.

[0041] Preferably, the electrolyte additive further includes fluoroethylene carbonate.

[0042] As a further solution, the wide temperature range sodium ion battery electrolyte further includes sodium salt and an organic solvent.

[0043] As a further embodiment, the sodium salt is selected from one or more of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, sodium difluorooxalatoborate, sodium bis(oxalatoborate), sodium difluorophosphate, sodium nitrate, sodium hexafluoroantimonate, sodium hexafluoroarsenate, sodium difluorobis(oxalatophosphate), and sodium tetrafluorooxalatophosphate.

[0044] As a further embodiment, the sodium salt is sodium hexafluorophosphate.

[0045] As a further preferred solution, the mass percentage of the sodium salt in the electrolyte is 5% to 20%.

[0046] As a further preferred solution, the mass percentage of the sodium salt in the electrolyte is 7.5% to 15%.

[0047] As a further preferred solution, the mass percentage of the sodium salt in the electrolyte is 13.5%.

[0048] The organic solvent includes one or more of a cyclic carbonate solvent, a chain carbonate solvent, a carboxylate solvent, a phosphate solvent, an ether solvent, and an ionic liquid.

[0049] As a further embodiment, the ether solvent is selected from one or more of ether solvents containing hydroxyl groups, ether solvents containing a single ether bond, and ether solvents containing complex functional groups.

[0050] As a further embodiment, the complex functional group is selected from one or more of C1-C10 alkoxy, alkenyl, and alkynyl groups.

[0051] As a further solution, the hydroxyl-containing ether solvent is selected from one or more of dipropylene glycol butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, triethylene glycol monomethyl ether, and tetraethylene glycol dimethyl ether.

[0052] As a further solution, the ether solvent containing a single ether bond is selected from one or more of cyclopentyl methyl ether, ethyl ether, and propyl ether.

[0053] As a further solution, the ether solvent containing complex functional groups is selected from one or more of butynediol dipropoxy ether, propargyl ether, and propargyl ether.

[0054] As a further embodiment, the chain carbonate solvent is selected from one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, and ethyl propyl carbonate.

[0055] As a further embodiment, the carboxylate solvent is selected from one or more of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, methyl isobutyrate, ethyl butyrate, methyl trimethylacetate and ethyl trimethylacetate.

[0056] As a further embodiment, the cyclic carbonate solvent is selected from one or more of ethylene carbonate, vinylene carbonate, butylene carbonate, propylene carbonate, and pentyl carbonate.

[0057] As a further embodiment, the phosphate solvent includes at least one of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl)phosphite and ethoxy(pentafluoro)cyclotriphosphazene.

[0058] The present invention also provides a wide temperature range sodium ion battery, comprising the wide temperature range sodium ion battery electrolyte, and also comprising a positive electrode sheet, a negative electrode sheet and a separator.

[0059] As a further solution, the positive electrode plate is an aluminum foil coated with a positive electrode active material, and the negative electrode plate is a copper foil or an aluminum foil coated with a negative electrode active material.

[0060] As a further solution, the positive electrode active material is one of sodium vanadium phosphate, sodium iron phosphate, sodium vanadium fluorophosphate, and a metal layered oxide containing manganese.

[0061] As a further preferred embodiment, the positive electrode active material is a metal layered oxide containing manganese, and the metal layered oxide containing manganese is generally formulated as Na x Mn y M zO₂, where 0.95 < x ≤ 1.05, 0.01 ≤ y ≤ 0.6, y + z = 1, and M represents a transition metal element with unfilled d electron orbitals, specifically including one or more of scandium (Sc), yttrium (Y), lanthanide elements (from lanthanum (La) to lutetium (Lu)), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), copper (Cu), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), and mercury (Hg).

[0062] As a further solution, M in the positive electrode active material containing manganese element includes at least one of Ni, Fe, and Cu.

[0063] The negative electrode active material is selected from at least one of soft carbon, hard carbon, expanded graphite, phosphorus-carbon composite material, and expanded graphite / hard carbon composite material.

[0064] Preferably, the negative electrode active material is hard carbon.

[0065] As a further solution, when the positive electrode active material is coated with an aluminum foil sheet or the negative electrode active material is coated with a copper foil sheet or an aluminum foil sheet, a binder and a conductive agent are also used.

[0066] As an even further solution, the binder is an oil-based binder, and the binder includes at least one of thermoplastic resin, acrylic resin, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0067] As a further solution, the thermoplastic resin includes at least one of polyvinylidene fluoride, copolymer of vinylidene fluoride, polytetrafluoroethylene, copolymer of vinylidene fluoride - hexafluoropropylene, copolymer of tetrafluoroethylene - hexafluoropropylene, copolymer of tetrafluoroethylene - perfluoroalkyl vinyl ether, copolymer of ethylene - tetrafluoroethylene, copolymer of vinylidene fluoride - tetrafluoroethylene, copolymer of vinylidene fluoride - trifluoroethylene, copolymer of vinylidene fluoride - trichloroethylene, copolymer of vinylidene fluoride - fluoroethylene, copolymer of vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene.

[0068] As a further solution, the acrylic resin includes at least one of acrylic vinyl ester resin, acrylic methyl ester resin, acrylic butyl ester resin, acrylic styrene resin, acrylic ester resin, acrylic ester copolymer resin, acrylic resin, and acrylic emulsion resin.

[0069] As a further solution, the binder is one or more of polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC).

[0070] As a further solution, the conductive agent includes one or more of conductive carbon black (Super P), conductive carbon balls, conductive graphite, carbon nanotubes (CNTs), conductive carbon fibers, graphene, and reduced graphene oxide.

[0071] As a further preferred solution, the conductive agent is one or more of conductive carbon black (Super P) and carbon nanotubes (CNTs).

[0072] As a further solution, the preparation of the wide temperature range sodium ion battery includes the following steps:

[0073] S1: The electrolyte solvent is fully mixed according to the target stoichiometric ratio, and then the sodium salt is dissolved in the mixed solvent according to the target stoichiometric ratio, and the target stoichiometric ratio of fluoroethylene carbonate, the first additive A, and the second additive B are added and stirred to obtain an electrolyte;

[0074] S2: dissolving the positive electrode active material, conductive agent, and binder in a solvent N-methyl-2-pyrrolidone (NMP) according to a target stoichiometric ratio, stirring evenly to obtain a positive electrode slurry, and then evenly coating the obtained positive electrode slurry on an aluminum foil, drying, cold pressing, and slitting to obtain a positive electrode sheet;

[0075] S3: The negative electrode active material, conductive agent, and binder are mixed according to the target stoichiometric ratio, deionized water is added and stirred evenly to obtain a negative electrode slurry, which is then coated on aluminum foil, and then dried, cold pressed, and cut into pieces to obtain negative electrode sheets;

[0076] S4: The positive electrode sheet, the negative electrode sheet, and the separator are formed into a battery through a winding process or a lamination process.

[0077] The characteristics and beneficial effects of the present invention are:

[0078] The sodium ion battery provided by the present invention has achieved a breakthrough improvement in the performance of the entire temperature range through multi-dimensional collaborative innovation, controlling the compaction density of the negative electrode sheet and the specific surface area of ​​the negative electrode active material within a specific range, and using cyclic and chain sulfonyl additives in the electrolyte to jointly participate in the passivation reaction of the negative electrode surface. On the one hand, a gradient reduction system of cyclic sulfonate and chain sulfonate additives is adopted to achieve the multi-level structure of the SEI membrane by precisely controlling the mass ratio, while meeting the requirements of high-temperature mechanical stability and low-temperature ion transport; on the other hand, a collaborative control model of the specific surface area and compaction density of the negative electrode material is established, and the pore size is achieved by controlling the compaction density of the negative electrode sheet and the specific surface area of ​​the negative electrode active material within a specific range. The balance between gaps / active sites ensures the continuity of the ion transmission path and the film-forming characteristics of the electrolyte on the electrode under the condition of structural strength and stability, and reduces the increase of battery impedance during the cycle: Thirdly, the electrolyte additives are quantitatively related to the physical properties of the electrode through the dynamic adaptation equation (a+b) / 0.01(c*ρ). The present invention further optimizes the c / ρ ratio to achieve synchronous optimization of the film-forming characteristics, ionic conductivity and cycle stability of the SEI film; the present invention breaks through the difficulties of traditional technologies and realizes the synergistic improvement of the cycle life, battery and safety of sodium ion batteries in the full temperature range through molecular design, structural matching and interface regulation, providing a solution for energy storage systems in extreme environments. BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION

[0079] To facilitate understanding of the present invention, a wide-temperature-range sodium-ion battery will be described more comprehensively below in combination with specific details and embodiments of the present invention, but the scope of the present invention is not limited thereby.

[0080] The present invention first provides a wide temperature range sodium ion battery electrolyte;

[0081] The wide temperature range sodium ion battery electrolyte includes an electrolyte additive;

[0082] The electrolyte additives include a first additive A and a second additive B;

[0083] The first additive A is selected from one or more compounds having a cyclic sulfonyloxy structure and has the following structure:

[0084] Wherein, R1 is selected from one of an oxygen atom and a C1-C3 alkylene group;

[0085] R2 is selected from C1 to C3 halogenated or non-halogenated hydrocarbon groups, One of the following;

[0086] R3 is selected from one of a hydrogen atom, a halogen atom, a C1-C3 halogenated or non-halogenated alkyl group, and a C2-C3 halogenated or non-halogenated alkenyl group,

[0087] R4, R5, R6, and R7 are each independently selected from a C1-C3 halogenated or non-halogenated hydrocarbon group and an oxygen atom, and at least one of R4 and R5 is an oxygen atom, and at least one of R6 and R7 is an oxygen atom;

[0088] Preferably, the ring where R1 and R2 are located in the structure of the first additive A is a five-membered ring to a seven-membered ring;

[0089] Specifically, when the ring where R1 and R2 are located in the structure of the first additive A is a five-membered ring, the total number of carbon atoms of R1 and R2 in the five-membered ring is 2;

[0090] When the ring containing R1 and R2 in the structure of the first additive A is a six-membered ring, the total number of carbon atoms of R1 and R2 in the six-membered ring is 3;

[0091] When the ring containing R1 and R2 in the structure of the first additive A is a seven-membered ring, the total number of carbon atoms of R1 and R2 in the seven-membered ring is 4;

[0092] The second additive B is selected from one or more chain compounds containing a sulfonyloxy structure and has the following structure:

[0093]

[0094] wherein R8 is selected from an alkali metal atom, a C1-C6 halogenated or non-halogenated hydrocarbon group, a C1-C6 halogenated or non-halogenated acyl group, a halogenated or non-halogenated sulfonyl group, or a halogenated or non-halogenated silyl group;

[0095] wherein R9 is selected from one of halogen, C1-C6 halogenated or non-halogenated hydrocarbon group, C1-C6 halogenated or non-halogenated hydrocarbonoxy group, C1-C6 halogenated or non-halogenated ester group (R10COO—), C1-C6 halogenated or non-halogenated sulfonic acid group (R11SO3—);

[0096] wherein R10 is selected from one of C1-C5 halogen atoms, halogenated or non-halogenated hydrocarbon groups, and R11 is selected from one of C1-C6 halogen atoms, halogenated or non-halogenated hydrocarbon groups;

[0097] The amounts of the first additive A and the second additive B in the electrolyte satisfy the following formula: 1.25≤(a+b) / 0.01(c*ρ)≤130, and 0.1%≤a≤5%, 0.01%≤b≤3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3≤ρ≤1.15g / cm 3 , where a is the mass percentage of the first additive A in the electrolyte; b is the mass percentage of the second additive B in the electrolyte; c is the specific surface area of ​​the negative electrode material; and ρ is the compaction density of the negative electrode sheet.

[0098] The above-mentioned design of the present invention solves the problems of poor electrochemical performance, poor cycle performance, poor stability, increased battery impedance and narrow temperature range of sodium ion batteries at high and low temperatures by optimizing the composition and mass ratio of the first additive A and the second additive B, the specific surface area of ​​the negative electrode material, and the compaction density of the negative electrode sheet in the battery, and combining it with a unique multi-dimensional adjustment and control mechanism while satisfying certain formula relationships.

[0099] Because at high temperatures, the thermal motion of molecules increases the solubility of the SEI film, and the volume change during the charge and discharge process makes the SEI film more prone to rupture, and the rate of side reactions between the electrolyte and the negative electrode is accelerated, which will cause the SEI film to continue to grow and thicken. The thickened SEI film will increase the resistance to sodium ion migration, increase the internal resistance of the battery, and reduce the charge and discharge efficiency. Moreover, the growth of the SEI film at high temperatures may be uneven, which will lead to uneven local current density distribution, further affecting the performance of the battery and causing battery capacity decay; because the viscosity of the electrolyte increases at low temperatures, the sodium ion transmission rate in the electrolyte decreases, the migration activity of ions between the positive and negative electrodes decreases, the conductivity decreases, the sodium ion desolvation process at the interface between the electrode and the electrolyte is hindered, and the sodium ions in the interface layer are difficult to move. At the same time, the transmission of electrons and sodium ions in the electrode is also restricted. The restriction of charge transfer leads to a decline in the overall performance of the battery.

[0100] However, using conventional electrolyte additives is difficult to improve kinetic performance and stability at high and low temperatures. Furthermore, the selection of these methods and process control are crucial. Improper operation can affect the electrochemical properties of electrode materials, often compromising some aspects of other performance, such as energy density and long cycle life, making it difficult to achieve an optimal balance of overall performance. This invention develops a sodium-ion battery that balances energy density and cycle performance at high and low temperatures. This innovative approach combines electrode interface microstructure control with electrolyte component kinetics, forming a unique multi-dimensional regulatory control mechanism.

[0101] By simultaneously using a cyclic sulfonate additive and a chain sulfonate additive in the electrolyte to participate in the passivation reaction on the negative electrode surface, and optimizing the mass percentage of the electrolyte additives, when the mass percentage a of the first additive A and the mass percentage b of the second additive B in the electrolyte meet the conditions: 0.1% ≤ a ≤ 5%, 0.01% ≤ b ≤ 3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3 ≤ρ≤1.15g / cm 3, and satisfying the formula relationship of 1.25≤(a+b) / 0.01(c*ρ)≤130, the obtained sodium ion battery has excellent low-temperature / high-temperature charging performance and cycle performance, while reducing the increase in impedance during the cycle. Because the first additive A, i.e., the compound containing a cyclic sulfonate structure, with a higher film-forming potential, is reduced first on the negative electrode with a specific compaction density and specific surface area, its cyclic structure imparts a unique electron cloud distribution pattern. The sulfonyl functional group in the cyclic sulfonate group has a relatively concentrated and stable electron cloud density due to the conjugation effect of the cyclic skeleton. When the battery is in the charging state, the electron cloud density is enriched on the negative electrode surface. This special electron cloud distribution makes the cyclic sulfonate additive more attractive to electrons. Compared with the chain sulfonate additive, it is more likely to be the first to accept electrons and initiate the reduction reaction, forming a high-molecular-weight polymer or cross-linked structure containing components such as sulfite and thiosulfate, providing an initial SEI film with high mechanical strength and thermal stability. The second additive B, i.e., the compound with a chain sulfonate structure, is reduced later at a lower potential. Its main reduction products are mainly low-molecular-weight sulfide salts, thiolate salts, or thioether organic compounds and inorganic salts, forming a relatively linear structure with relatively unobstructed channels, resulting in the formation of a dense SEI film with high ionic conductivity. This sequential reduction process creates a multi-layered SEI membrane structure, ensuring the battery's mechanical strength while also improving ionic conductivity. By optimizing the electrolyte type and ensuring a certain mass ratio of cyclic sulfonate-based additives to chain sulfonate-based additives, the present invention creates an SEI membrane that possesses both sufficient strength to support the electrolyte-electrode interface at high temperatures and unobstructed ion channels to meet electrochemical performance requirements at low temperatures. This ensures ion transport rates and enhances membrane stability, resulting in sodium-ion batteries exhibiting excellent wide-temperature performance.

[0102] The present invention controls the compaction density of the negative electrode sheet and the specific surface area of ​​the negative electrode material within a specific range. The specific surface area is measured using an automatic adsorption and desorption instrument, the adsorbate is nitrogen, the measurement temperature is 77K, and the specific surface area is calculated by the BET method. The specific surface area affects the reactivity of the material, because a larger specific surface area means more reaction sites, which may improve the efficiency of sodium ion insertion and extraction, but it also increases the risk of side reactions, such as the formation of SEI film and the decomposition of the electrolyte. Too low a specific surface area may cause the sodium ion transport kinetics to be limited, resulting in increased electrode polarization and insufficient capacity. Too low a specific surface area will reduce the contact interface between the active material and the electrolyte, extend the diffusion path of sodium ions in the solid phase material, and easily cause a sharp decline in capacity, especially in charging and discharging scenarios at extreme temperatures. The present invention also controls the compaction density of the negative electrode sheet, compaction density = coating surface density / (thickness of the electrode sheet after extrusion - thickness of the current collector). Increasing the compaction density can effectively improve the volume energy density and weight energy density of the electrode, but this will also affect the electrode structure, such as porosity, specific surface area, pore size distribution and tortuosity, and will also affect the distribution of binders and conductive agents in the electrode, which will have a significant impact on the electrochemical performance of the sodium ion battery. Increasing the compaction density reduces the distance between particles, makes the contact closer, and enhances electronic conductivity, but reduces or blocks the ion movement channels, increases the risk of particle breakage, and is not conducive to the rapid movement of a large number of ions, thereby limiting its high current discharge and polarization during discharge. Reducing the compaction density increases the distance between particles, increases the ion channels, increases the amount of electrolyte absorbed and fully infiltrated, which is conducive to the rapid movement of ions, but because the distance between particles is too large, the contact probability and contact area between particles are reduced, which is not conducive to electron transmission. Therefore, a suitable compaction density range can ensure sufficient contact between particles without blocking ion movement channels, while also ensuring good electron conductivity and rapid ion movement during high-current discharge, reducing discharge polarization and increasing the discharge platform voltage. Therefore, a reasonable negative electrode sheet compaction density and negative electrode material specific surface area are crucial for fine-tuning the electrode interface microstructure under extreme high and low temperature conditions, which is of great significance to the battery's electrochemical activity, interface stability, and capacity retention at extreme temperatures.

[0103] The present invention simultaneously optimizes the range of the formula (a+b) / 0.01(c*ρ) to ensure that the formation of the SEI film satisfies a certain relationship with the compaction density of the negative electrode sheet and the specific surface area of ​​the negative electrode material. The sum of a and b in the formula reflects the complementarity of the reduction products. The reduction products of the chain sulfonate additive primarily contribute to the ion transport performance of the SEI film, effectively alleviating the ion transport barrier caused by the use of the cyclic sulfonate additive alone, while the reduction products of the cyclic sulfonic acid additive contribute to the high-temperature stability of the SEI film and provide sufficient interfacial film strength. The reduction products of the two complement each other in the SEI film, resulting in the SEI film having both low impedance and high stability. The cyclic sulfonate additive first undergoes a reduction reaction on the negative electrode surface, forming an initial SEI film with a certain stability, which provides a stable basic environment for the subsequent reaction of the chain sulfonate additive. The chain sulfonyl additive then continues to react on the existing initial film, forming a fast ion transport channel, which compensates for the relatively slow ion transport that may be caused by the cyclic structure. The combination of these two factors results in a SEI film that exhibits both excellent high-temperature stability and rapid ion transport at low temperatures, extending the battery's temperature range. The product of c and ρ demonstrates a synergistic relationship between the specific surface area of ​​the anode material and the anode sheet compaction density; either value being too low or too high significantly impacts battery performance. Furthermore, the sum of a and b, divided by the product of c and ρ, further illustrates the close relationship between the electrolyte additive and the anode sheet specific surface area and compaction density, resulting in a dynamic adaptation of the additive dosage to the anode interface characteristics. When the ratio of the electrolyte additive to the anode specific surface area and compaction density is within the target range, the electrolyte additive can better infiltrate the anode at a certain compaction density and specific surface area, balance the sodium ion flux by regulating the active site density, and form a stable electrolyte membrane, achieving a balanced battery cycling performance at different temperatures. This model transcends the limitations of traditional methods of controlling electrolyte or electrode parameters in isolation, expanding the battery's temperature range.

[0104] As a further preferred example, the amounts of the first additive A and the second additive B in the electrolyte further satisfy 5≤(a+b) / 0.01(c*ρ)≤80.

[0105] Further optimizing the range of the (a+b) / 0.01(c*ρ) formula can further improve the adaptability at high and low temperatures, balance the electrolyte additives in the electrode film formation and the compaction density of the negative electrode material particles at extreme temperatures, thereby further improving the ion transmission capacity and structural strength at extreme temperatures, reducing the increase in battery impedance, the decline in cycle performance, the side reactions and gas production problems at the electrode interface at high or low temperatures, and achieving better performance at both low and high temperatures.

[0106] As a further preferred example, when the above-mentioned 0.01%≤m1≤2.5%, 0.01%≤m2≤2.5%, 0.85g / cm3≤ρ≤1.15g / cm3, 6μm≤d≤15μm, 5≤(a+b) / 0.01(c*ρ)≤80 are satisfied, and 2≤c / ρ≤10 is satisfied at the same time, the performance is better.

[0107] Further optimize the relationship between the specific surface area of ​​the anode material and the compaction density of the anode sheet within a certain ratio range to adapt to wide-temperature battery application scenarios and improve battery cycling performance in a wide temperature range. Customized designs are implemented based on wide-temperature scenarios, balancing the emphasis on ion transport at low temperatures with the emphasis on structural stability at high temperatures. When the specific surface area is high and the compaction density is low, the c / ρ ratio is large. This means that while the material has many active sites, providing more reaction interfaces for sodium ion insertion / extraction and facilitating the adsorption of more electrolyte, the anode active particles are not tightly packed together, which may lead to a loose electrode structure and uneven SEI film thickening at low temperatures, affecting conductivity, cycling stability, and volumetric energy density. This can also increase the likelihood of side reactions and shorten cycle life. Conversely, a low specific surface area, high compaction density, and a low c / ρ ratio may result in greater structural stability but limited capacity or rate performance. The material particles are tightly packed, but the active sites are insufficient, potentially affecting battery capacity and rate performance. When the specific surface area of ​​the negative electrode material and the compaction density of the negative electrode sheet are in a certain relationship, sufficient active sites are guaranteed, and the active material is not too loose or tight, satisfying the balance of structural stability, electronic conductivity, and cycle stability under a certain temperature range.

[0108] At this time, the capacity retention rate of 500 cycles at 45℃1C is ≥93.9%, the impedance growth rate of 500 cycles at 45℃1C is ≤7%, the capacity retention rate of 10 cycles at 20℃0.2C is ≥99%, and the average coulombic efficiency of 10 cycles at 20℃0.2C is ≥99.9%.

[0109] As a further preferred example, in the first additive A, R1 is selected from one of an oxygen atom and a C1-C3 alkylene group; R2 is selected from one of a C1-C3 non-halogenated hydrocarbon group, R3 is selected from a hydrogen atom, a halogen atom, one of C1 to C3 non-halogenated alkyl groups, or one of C2 to C3 halogenated or non-halogenated alkenyl groups.

[0110] As a further preferred example, in the first additive A, R1 is selected from one of an oxygen atom and a C1 alkylene group; R2 is selected from one of a C1-C3 non-halogenated alkylene group, One of them.

[0111] As a further preferred example, the first additive A is selected from one or more of Compounds 1 to 23:

[0112]

[0113]

[0114] As a further preferred example, the first additive A is one or more of Compound 1, Compound 2, Compound 22, Compound 7, and Compound 23.

[0115] As a further preferred example, in the second additive B, R8 is selected from an alkali metal atom, a C1-C3 halogenated alkyl group, a C1-C3 halogenated ester group, a C1-C3 halogenated sulfonyl group, and a C3-C6 silane group, and R9 is selected from a halogen atom, a C1-C3 halogenated hydrocarbon group, and a C1-C3 halogenated hydrocarbonoxy group.

[0116] As a further preferred example, in the second additive B, R8 is selected from an alkali metal atom and a C1-C3 halogenated alkyl group, and R9 is selected from a halogen atom, a C1 halogenated hydrocarbon group, and a C1 halogenated hydrocarbonoxy group.

[0117] The second additive B is selected from one or more of compounds 24 to 48:

[0118]

[0119] As a further preferred example, the second additive B is one or more of compound 24, compound 25, compound 30, compound 34, and compound 35.

[0120] As a further preferred example, the electrolyte additive further includes fluorinated carbonate.

[0121] The fluorocarbonate is selected from one or more of fluoroethylene carbonate, trifluoromethylethylene carbonate, and bisfluoroethylene carbonate.

[0122] As a further example, the wide temperature range sodium ion battery electrolyte also includes sodium salt and an organic solvent.

[0123] As a further example, the sodium salt is selected from one or more of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, sodium difluorooxalatoborate, sodium bis(oxalatoborate), sodium difluorophosphate, sodium nitrate, sodium hexafluoroantimonate, sodium hexafluoroarsenate, sodium difluorobis(oxalatophosphate), and sodium tetrafluorooxalatophosphate.

[0124] As a further example, the sodium salt is sodium hexafluorophosphate.

[0125] As a further preferred example, the mass percentage of the sodium salt in the electrolyte is 5% to 20%.

[0126] As a further preferred solution, the mass percentage of the sodium salt in the electrolyte is 7.5% to 15%.

[0127] As a further preferred example, the mass percentage of the sodium salt in the electrolyte is 13.5%.

[0128] The organic solvent includes one or more of a cyclic carbonate solvent, a chain carbonate solvent, a carboxylate solvent, a phosphate solvent, an ether solvent, and an ionic liquid.

[0129] As a further example, the ether solvent is selected from one or more of ether solvents containing hydroxyl groups, ether solvents containing a single ether bond, and ether solvents containing complex functional groups.

[0130] As a further example, the complex functional group is selected from one or more of C1-C10 alkoxy, alkenyl, and alkynyl groups.

[0131] As a further example, the hydroxyl-containing ether solvent is selected from one or more of dipropylene glycol butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, triethylene glycol monomethyl ether, and tetraethylene glycol dimethyl ether.

[0132] As a further example, the ether solvent containing a single ether bond is selected from one or more of cyclopentyl methyl ether, ethyl ether, and propyl ether.

[0133] As a further example, the ether solvent containing complex functional groups is selected from one or more of butynediol dipropoxy ether, propargyl ether, and propargyl ether.

[0134] As a further example, the linear carbonate solvent is selected from one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, and ethyl propyl carbonate.

[0135] As a further example, the carboxylate solvent is selected from one or more of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, methyl isobutyrate, ethyl butyrate, methyl trimethylacetate and ethyl trimethylacetate.

[0136] As a further example, the cyclic carbonate solvent is selected from one or more of ethylene carbonate, vinylene carbonate, butylene carbonate, propylene carbonate, and pentylene carbonate.

[0137] As a further example, the phosphate solvent includes at least one of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl) phosphite, and ethoxy(pentafluoro)cyclotriphosphazene.

[0138] The present invention also provides a wide-temperature sodium-ion battery, including the wide-temperature sodium-ion battery electrolyte, and further including a positive electrode sheet, a negative electrode sheet, and a separator.

[0139] As a further example, the positive electrode sheet is an aluminum foil sheet coated with a positive electrode active material, and the negative electrode sheet is a copper foil sheet or an aluminum foil sheet coated with a negative electrode active material.

[0140] As a further example, the positive electrode active material is one of sodium vanadium phosphate, sodium iron phosphate, sodium fluorovanadate, and a manganese-containing metal layered oxide.

[0141] As a further preferably example, the positive electrode active material is a manganese-containing metal layered oxide, and the general formula of the manganese-containing metal layered oxide is Na x Mn y M z O2, where 0.95 < x ≤ 1.05, 0.01 ≤ y ≤ 0.6, y + z = 1, and M represents a transition metal element with an unfilled d electron orbital, specifically including one or more of scandium (Sc), yttrium (Y), lanthanide elements (from lanthanum (La) to lutetium (Lu)), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), copper (Cu), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), and mercury (Hg).

[0142] As a further example, M in the manganese-containing positive electrode active material includes at least one of Ni, Fe, and Cu.

[0143] The negative electrode active material is selected from at least one of soft carbon, hard carbon, expanded graphite, phosphorus-carbon composite material, and expanded graphite / hard carbon composite material.

[0144] Preferably, the negative electrode active material is hard carbon.

[0145] As a further example, when the positive electrode active material is coated on an aluminum foil sheet or the negative electrode active material is coated on an aluminum foil sheet, a binder and a conductive agent are also used.

[0146] As a further example, the binder is an oil-based binder, and the binder includes at least one of thermoplastic resin, acrylic resin, sodium carboxymethyl cellulose and styrene butadiene rubber.

[0147] As a further example, the thermoplastic resin includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of vinylidene fluoride-tetrafluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, a copolymer of vinylidene fluoride-trichloroethylene, a copolymer of vinylidene fluoride-fluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene.

[0148] As a further example, the acrylic resin includes at least one of vinyl acrylate resin, methyl acrylate resin, butyl acrylate resin, acrylic styrene resin, acrylate resin, acrylate copolymer resin, acrylic resin, and acrylic emulsion resin.

[0149] As a further example, the binder is one or more of polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC).

[0150] As a further example, the conductive agent includes one or more of conductive carbon black (Super P), conductive carbon balls, conductive graphite, carbon nanotubes (CNTs), conductive carbon fibers, graphene, and reduced graphene oxide.

[0151] As a further preferred example, the conductive agent is one or more of conductive carbon black (Super P) and carbon nanotubes (CNTs).

[0152] As a further example, the preparation of the wide temperature range sodium ion battery includes the following steps:

[0153] S1: The electrolyte solvent is fully mixed according to the target stoichiometric ratio, and then the sodium salt is dissolved in the mixed solvent according to the target stoichiometric ratio, and the target stoichiometric ratio of fluoroethylene carbonate, the first additive A, and the second additive B are added and stirred to obtain an electrolyte;

[0154] S2: dissolving the positive electrode active material, conductive agent, and binder in a solvent N-methyl-2-pyrrolidone (NMP) according to a target stoichiometric ratio, stirring evenly to obtain a positive electrode slurry, and then evenly coating the obtained positive electrode slurry on an aluminum foil, drying, cold pressing, and slitting to obtain a positive electrode sheet;

[0155] S3: The negative electrode active material, conductive agent, and binder are mixed according to the target stoichiometric ratio, deionized water is added and stirred evenly to obtain a negative electrode slurry, which is then coated on aluminum foil or copper foil, and then dried, cold pressed, and cut into pieces to obtain negative electrode sheets;

[0156] S4: The positive electrode sheet, the negative electrode sheet, and the separator are formed into a battery through a winding process or a lamination process.

[0157] As a specific embodiment of the present invention, the following detailed cases are provided:

[0158] Example 1:

[0159] This embodiment provides a wide temperature range sodium ion battery, which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte.

[0160] The positive electrode sheet includes a positive electrode active material NaCu 1 / 20 Ni 6 / 20 Fe 6 / 20 Mn 7 / 20 O2, conductive carbon black Super-P, conductive agent CNT, binder polyvinylidene fluoride (PVDF) and aluminum foil;

[0161] The negative electrode sheet includes negative electrode active material hard carbon, conductive carbon black Super-P, binder styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) and aluminum foil;

[0162] Preparation of the electrolyte: In an argon atmosphere, the environmental indicators of the glove box are H2O≤0.5ppm, O2≤0.5ppm, firstly, the solvents propylene carbonate, diethyl carbonate and ethyl methyl carbonate are mixed in a mass ratio of 1:1:1, then the sodium salt NaPF6 is dissolved in the mixed solvent, and then fluoroethylene carbonate, the first additive A compound 1 and the second additive B compound 24 are added and stirred evenly to obtain an electrolyte; based on the total mass of the electrolyte, the mass percentage of the sodium salt NaPF6 is 13.5%, the mass percentage of the first additive A is 0.1%, and the mass percentage of the second additive B is 0.5%. The mass percentage of the fluoroethylene carbonate is 1%

[0163] Preparation of the positive electrode sheet: the positive electrode active material NaCu 1 / 20 Ni 6 / 20 Fe 6 / 20 Mn 7 / 20O2, conductive agent SuperP, conductive agent CNT, and binder PVDF are dissolved in solvent N-methyl-2-pyrrolidone (NMP) in a mass ratio of 96.5:1.5:0.5:1.5, and stirred evenly to obtain a positive electrode slurry with a slurry viscosity of 5000±1000mPa·s and a solid content of 65±0.5wt%. The obtained positive electrode slurry is then evenly coated on aluminum foil, and then dried, cold pressed, and cut to obtain positive electrode sheets.

[0164] Preparation of the negative electrode sheet: The negative electrode active material hard carbon, conductive agent Super P, binder CMC, and binder SBR are mixed in a mass ratio of 94:2:1.5:2.5, and deionized water is added and stirred evenly to obtain a negative electrode slurry. The slurry viscosity is adjusted to 4500±500mPa·s and the solid content is 50±0.5wt%; then the slurry is coated on the negative electrode current collector aluminum foil, and then dried, cold pressed, and cut to obtain the negative electrode sheet. The compaction density of the negative electrode sheet is controlled to be 1g / cm 3 The specific surface area c value of the negative electrode active material is 10 g / cm 2 .

[0165] Preparation of the sodium ion battery: The positive electrode sheet, the negative electrode sheet, and the separator are formed into an electrode assembly through a winding process or a lamination process. This embodiment adopts the winding process.

[0166] The outer packaging of the sodium ion battery can be a bag-type soft package or an aluminum shell, steel shell, etc. The shape of the sodium ion battery is not limited and can be cylindrical, square or any other shape. This embodiment uses a cylindrical aluminum shell.

[0167] Under the above conditions, the following tests were performed:

[0168] (1) Low temperature cycle test: At a low temperature of -20°C, charge at 0.2C and discharge at 0.2C, perform charge and discharge cycles, and record the capacity retention rate and average coulombic efficiency after 10 cycles.

[0169] (2) High temperature cycle test: At a high temperature of 45°C, charge and discharge at 1C, perform charge and discharge cycles, and record the capacity retention rate and impedance growth rate after 500 cycles.

[0170] Examples 2 to 31, Comparative Examples 1 to 11:

[0171] A sodium ion battery was prepared and tested in the same manner as in Example 1, with some parameters modified. The parameter modifications and results are listed in Table 1.

[0172] The test results obtained in Examples 1 to 31 and Comparative Examples 1 to 11 are shown in Table 1:

[0173] Table 1

[0174]

[0175]

[0176] From Examples 1 to 31 and Comparative Examples 1 to 11, it can be observed that:

[0177] When 0.1%≤a≤5%, 0.01%≤b≤3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3 ≤ρ≤1.15g / cm 3 , and when the formula relationship of 1.25≤(a+b) / 0.01(c*ρ)≤130 is satisfied, the battery has a capacity retention rate of ≥89% for 500 cycles at 45°C 1C, and an impedance growth rate of ≤10%. The performance at high temperature is significantly better than that of the embodiment. At -20°C 0.2 cycle for 10 cycles, the capacity retention rate (%) is ≥99.1%, and the coulombic efficiency (%) is greater than or equal to 99.9%. The above parameters can ensure the performance of the sodium ion battery at high and low temperatures, which is better than the comparative example, meets the cycle performance of the sodium ion battery at high and low temperatures, and reduces the impedance.

[0178] Comparative Examples 1 to 7, 10 to 11 show that when 0.1%≤a≤5%, 0.01%≤b≤3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3 ≤ρ≤1.15g / cm 3 Under these parameters, the low-temperature performance and high-temperature performance of sodium-ion batteries cannot be guaranteed at the same time.

[0179] Comparative Examples 1 to 2 and Comparative Example 4 are respectively the cases of no additives, only the second additive B, and only the first additive A; at this time, the 500-week capacity retention rate under high-temperature cycling, the impedance growth rate, the capacity retention rate at low temperature, and the coulombic efficiency cannot meet the use requirements under a wide temperature range. This shows that the first additive A and the second additive B play a key role in the formation and stabilization of the inorganic component-rich cross-linked polymer passivation layer, and neither of them can be missing. The lack of any of the two additives will lead to the instability of the SEI film, which is not conducive to the construction of a dense and complete S-rich interface film, and reduces the cycle life at high temperatures. The first additive preferentially forms a sulfur-rich inorganic skeleton Na2SO4 on the electrode surface, providing a mechanical barrier to meet the structural strength at high temperatures; the second additive forms a relatively linear structure with relatively smooth channels through low-molecular-weight sulfide salts, thiolates or thioether organic compounds and inorganic salts, so that a dense and highly ionic conductive SEI film is formed, further improving the low-temperature performance of the battery.

[0180] Comparative Examples 3 and 5 illustrate the use of an excess of either the first additive A or the second additive B. Excessive amounts of the first additive A can hinder ion transport at low temperatures due to the thick SEI film, increasing the sodium ion desolvation barrier, polarization, and electrolyte viscosity, thereby reducing the battery's cycling performance and coulombic efficiency. Excessive amounts of the second additive B, while forming a highly conductive SEI film, result in better performance at low temperatures. However, the relatively small amount of the first additive results in a weak SEI film structure, which increases side reactions and impedance at high temperatures, hindering cycling performance at high temperatures.

[0181] Comparative Examples 6 and 7 show the situation when the specific surface area of ​​the negative electrode active material is too low or too high. When the specific surface area is too low, the active sites are insufficient, resulting in a reduction in the reaction interface, insufficient electrolyte infiltration, slow sodium ion insertion / extraction kinetics, decreased charge transfer efficiency, and reduced capacity utilization rate. In particular, polarization is aggravated at low temperatures, the discharge capacity is significantly reduced, and the cycle capacity retention rate is significantly reduced, resulting in a decrease in coulombic efficiency. When the specific surface area is too high, the contact area between the negative electrode material and the electrolyte is large, the solvent is prone to decomposition and gas production at high temperatures, the dissolution of transition metals is accelerated, the SEI film continues to thicken, the active sodium loss is serious, the risk of structural collapse increases, and the cycle life is suddenly reduced. In particular, high temperature accelerates particle migration, the pores are blocked, and the ion transmission path is blocked, and the cycle performance is reduced at high temperatures.

[0182] Comparative Examples 10 and 11 show the cases where the compacted density is too low or too high:

[0183] When the compaction density is too low, the electrode porosity is high and the electrolyte is excessively infiltrated, which increases the contact area between the active material and the electrolyte. The side reactions (such as solvent decomposition and gas production) at high temperatures are accelerated, the SEI film continues to thicken, and Na + The loss is serious. The side reactions are aggravated in high temperature environment; the contact between particles is poor, and the volume expansion during charging and discharging can easily cause particle separation, break the electronic conduction network, and accelerate capacity decay. The electron transmission path is blocked, and the internal resistance increases significantly; excessive pores cause the sodium ion transmission path to be circuitous, and the concentration polarization is aggravated at high temperature. In low temperature environment, the electrolyte infiltration is uneven: the viscosity of the electrolyte increases at low temperature, and the loose structure leads to insufficient infiltration in local areas, uneven distribution of sodium ions, and decreased capacity utilization. The ion transmission path is long under low compaction density, the low temperature kinetic hysteresis is further amplified, and the discharge capacity drops sharply. The active site contact is insufficient, Na + The deintercalation efficiency is reduced, the SEI film growth in the pore area is out of control, the local impedance difference is large, and the overall internal resistance fluctuation is aggravated.

[0184] When the compaction density is too high, at high temperatures, volume expansion stress concentrates: at high compaction density, the electrode rigidity increases, the volume expansion during the sodiumation / de-sodiumation process cannot be effectively released, the risk of particle rupture increases, and the cycle life is shortened. The porosity is too low, resulting in insufficient electrolyte infiltration and runaway side reactions in local areas. The sodium ion migration channel is narrow, and byproducts easily clog the pores at high temperatures. Mechanical stress causes the SEI film to repeatedly rupture and repair, continuously consuming Na and electrolyte; at low temperatures, sodium ion transport is hindered: at high compaction density, the porosity is low, the low-temperature electrolyte has poor fluidity, and sodium ions have difficulty penetrating the dense electrode, limiting capacity utilization. The flexibility of high-density electrodes decreases, and microcracks are easily generated during low-temperature shrinkage, destroying the conductive network. The impedance increases, and microcracks lead to increased contact resistance between particles, breaking the electron conduction path, and sodium ion desolvation in the dense structure requires overcoming a higher energy barrier.

[0185] In particular, in Comparative Examples 8 and 9, the single parameters all satisfy 0.1%≤a≤5%, 0.01%≤b≤3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3 ≤ρ≤1.15g / cm 3 However, when the relationship of 1.25≤(a+b) / 0.01(c*ρ)≤130 is not satisfied, the results are also poor. The capacity retention rate of the battery after 500 cycles at 45℃1C is less than 90%, and the impedance growth rate after 500 cycles at 45℃1C is greater than 10%. This shows that when each condition is met separately, if 1.25≤(a+b) / 0.01(c*ρ)≤130 is not satisfied, the performance requirements cannot be met.

[0186] Under this formula, the additive is reduced to form a sulfur-containing SEI film on the surface of the negative electrode, which inhibits the dissolution of transition metals. The first additive A decomposes to form more SEI films with lower solubility, constructing a dense and complete S-rich interface film, which is beneficial to the Na in the SEI layer. +The conductivity of the battery is improved, and the content of the second additive B is within a suitable range, which effectively improves the ion transport performance of the SEI membrane and improves the cycle stability and low-temperature performance of the battery; the summation relationship between the first additive A and the second additive B shows that adding too little or too much of any additive will greatly reduce the synergistic effect of the two additives. The product of c and ρ shows that the specific surface area of ​​the negative electrode material and the compaction density of the negative electrode sheet have a synergistic relationship. Any aspect that is too low or too high will have a huge impact on the battery performance. At the same time, the sum of a and b, divided by the product of c and ρ, further illustrates that there is a close relationship between the electrolyte additive and the specific surface area of ​​the negative electrode sheet and the negative electrode sheet compaction density. The negative electrode interface structure characteristics formed by the close relationship realizes the dynamic adaptation of the additive dosage and the negative electrode interface characteristics. When the ratio of the electrolyte additive to the negative electrode specific surface area and the sheet compaction density is within the target range, since the electrolyte additive can better infiltrate the battery negative electrode with a certain compaction density and specific surface area, it can also balance the sodium ion flux by regulating the active site density, and the electrolyte can form a stable electrolyte membrane. At this time, the balance of battery cycle performance at different temperatures can be met. Therefore, when the formula relationship of 1.25≤(a+b) / 0.01(c*ρ)≤130 is satisfied, the relationship between the additive and the specific surface area of ​​the negative electrode material, and the compaction density of the negative electrode sheet in the battery is balanced, and the energy density and structural stability performance are balanced.

[0187] Comparing Examples 1-11 with Examples 28-31, when 5≤(a+b) / 0.01(c*ρ)≤80, the capacity retention after 500 cycles at 45°C / 1C was ≥93%. This demonstrates that further optimizing the range of the formula 5≤(a+b) / 0.01(c*ρ) can further optimize interfacial reactions, ion transport capabilities at extreme temperatures, and structural strength, reducing the increase in battery impedance, the decrease in cycling performance, and the side reactions and gas generation at the electrode interface at both high and low temperatures, thereby achieving better performance at both low and high temperatures.

[0188] By comparing Examples 1 to 7, 11 with Examples 8 to 10, when the ratio between the specific surface area of ​​the negative electrode material and the compaction density of the negative electrode sheet is further optimized to meet 2≤c / ρ≤10, while ensuring low-temperature performance, the impedance growth rate after 500 cycles at 45°C 1C is further reduced, and the capacity retention rate after 500 cycles at 45°C 1C is further improved, achieving a balance between focusing on ion transport at low temperatures and focusing on structural stability at high temperatures.

[0189] According to the comparison between Examples 2, 15 to 18 and Examples 12, 13, 14, 19 and 20, when the R2 group in the structure of the first additive A is a C1 to C3 non-halogenated alkyl group or When the relevant performance is better than R2 This may be because the non-halogenated alkyl groups of C1 to C3 have less steric influence on the core structure of the cyclic sulfonic acid. Compounds without bridging structures are more stable than those with bridging structures, are less likely to break under high temperature and high pressure, and are more suitable for applications in a wide temperature range.

[0190] According to the comparison between Examples 2, 22, 25, 26, and 27 and Examples 21, 23, and 24, when R8 in the second additive B is Na or a C1-C3 alkyl halide, the relevant performance is better than when it is other groups such as a halogen-containing sulfonic acid group. This may be because the sodium substituent itself contains a mobile Na + , forming pre-embedded ion transport channels within the SEI film, reducing the desolvation energy of sodium ions and forming pre-sodiumated ion transport channels, significantly improving the ion diffusion rate at low temperatures. The short-chain fluorinated hydrocarbon groups have highly electronegative fluorine atoms and significant dipole moments, making them more susceptible to strong adsorption and oriented alignment on the charged negative electrode surface. This ordered arrangement provides favorable sites for subsequent reduction reactions, promoting the formation of a more uniform and dense SEI film local structure. The strong polarity of the C-F bond effectively weakens the interaction between the solvated sodium ions and solvent molecules. In the second additive B, R9 is F, a F-containing hydrocarbon group, or a F-containing oxyalkyl group. The fluorine atoms, through their strong electron-withdrawing induction effect, reduce the electron cloud density of the reactive sites in the molecule, slowing the reduction rate at low potentials and making the SEI film formation process more controllable, avoiding the loose structure caused by rapid film formation. The combination of R8 and R9 balances the polarity of the second additive B, modulating the SEI film formation rate and structure, further improving performance at both low and high temperatures.

[0191] The core innovation of this invention lies in the construction of a dynamically adaptive composite SEI membrane system through multi-dimensional collaborative design. This fundamentally addresses the difficult challenge of balancing energy density and cycling performance in sodium-ion batteries across a wide temperature range. Unlike traditional strategies that rely on single additives or isolated parameter control, this invention innovatively combines electrode interface microstructure control with the kinetic response of electrolyte components, forming a unique multi-modulation mechanism.

[0192] The cyclic sulfonyl additive, with its rigid conjugated skeleton forming a delocalized electron cloud, preferentially triggers directional reduction in the high potential range of the negative electrode, generating a polymer matrix with a three-dimensional network structure, providing a mechanical support skeleton for the SEI membrane and significantly improving the orderliness of ion migration at high temperatures; while the chain sulfonyl additive achieves a synergistic multiplication of ionic conductivity and membrane structure stability by flexible insertion of molecular chains in the subsequent low potential stage.

[0193] By precisely controlling the synergistic relationship between the specific surface area and compaction density of the negative electrode active material, an electrode matrix with adaptive buffering properties was constructed. While maintaining a specific surface area within a specific range ensures sufficient reaction sites, optimizing the compaction density creates a reasonable pore distribution at the microscale. This not only reserves deformation space for high-temperature expansion, but also regulates the electrolyte wetting dynamics through capillary effects, ensuring rapid establishment of ion transport channels at low temperatures. This dual-parameter coupling creates a dynamic stress dissipation mechanism at the electrode-electrolyte interface, effectively suppressing interfacial delamination at extreme temperatures.

[0194] At the system synergy level, by establishing a functional relationship between the electrolyte additive ratio and the electrode structural parameters, a precise match of the SEI film growth process is achieved. The sequential reduction of cyclic and chain additives is not only reflected in the difference in potential response, but also realizes the ordered self-assembly of SEI film components at the molecular level through the chemical compatibility of their decomposition products. The cross-linked network formed by the cyclic components acts as a template to guide the directional filling of the chain products, while the flexible characteristics of the chain components enhance the interfacial adhesion of the network structure. This two-way synergistic effect enables the SEI film to have temperature-responsive reconstruction capabilities. At high temperatures, the network shrinks to enhance the structural density, and at low temperatures, the chain segments stretch to maintain ion permeability, thus giving the battery unique wide-temperature adaptive characteristics.

[0195] Through the innovative design of the above-mentioned multi-level synergistic mechanism, the sodium-ion battery of the present invention has achieved a major breakthrough in essence. This system-level innovation provides a new theoretical framework and technical path for the development of high-safety, wide-temperature range sodium-ion batteries, and has practical applications.

[0196] It should be noted that 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, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wide temperature range sodium ion battery electrolyte, characterized in that including electrolyte additives; The electrolyte additives include a first additive A and a second additive B; The first additive A is selected from one or more cyclic compounds containing a sulfonyloxy structure and has the following structure: Wherein, R1 is selected from one of an oxygen atom and a C1-C3 alkylene group; R2 is selected from C1 to C3 halogenated or non-halogenated hydrocarbon groups, One of the following; R3 is selected from one of a hydrogen atom, a halogen atom, a C1-C3 halogenated or non-halogenated alkyl group, and a C2-C3 halogenated or non-halogenated alkenyl group; R4, R5, R6, and R7 are each independently selected from a C1-C3 halogenated or non-halogenated hydrocarbon group and an oxygen atom, and at least one of R4 and R5 is an oxygen atom, and at least one of R6 and R7 is an oxygen atom; The second additive B is selected from one or more chain compounds containing a sulfonyloxy structure and has the following structure: wherein R8 is selected from an alkali metal atom, a C1-C6 halogenated or non-halogenated hydrocarbon group, a C1-C6 halogenated or non-halogenated acyl group, a halogenated or non-halogenated sulfonyl group, or a halogenated or non-halogenated silyl group; wherein R9 is selected from one of halogen, C1-C6 halogenated or non-halogenated hydrocarbon group, C1-C6 halogenated or non-halogenated hydrocarbonoxy group, C1-C6 halogenated or non-halogenated ester group (R10COO—), C1-C6 halogenated or non-halogenated sulfonic acid group (R11SO3—); R10 is selected from one of C1 to C5 halogen atoms, halogenated or non-halogenated hydrocarbon groups, and R11 is selected from one of C1 to C6 halogen atoms, halogenated or non-halogenated hydrocarbon groups; The amounts of the first additive A and the second additive B in the electrolyte satisfy the following formula: 1.25≤(a+b) / 0.01(c*ρ)≤130, and 0.1%≤a≤5%, 0.01%≤b≤3%, 2m 2 / g≤c≤25m 2 / g, 0.85g / cm 3 ≤ρ≤1.15g / cm 3 , where a is the mass percentage of the first additive A in the electrolyte; b is the mass percentage of the second additive B in the electrolysis; c is the specific surface area of ​​the negative electrode material; and ρ is the compaction density of the negative electrode sheet.

2. The wide temperature range sodium ion battery electrolyte according to claim 1, characterized in that The a, b, c, and ρ also satisfy 5≤(a+b) / 0.01(c*ρ)≤80.

3. The wide temperature range sodium ion battery electrolyte according to claim 1, characterized in that The c and ρ also satisfy 2≤c / ρ≤10.

4. The wide temperature range sodium ion battery electrolyte according to claim 1, characterized in that In the first additive A, R1 is selected from one of oxygen atoms and C1-C3 alkylene groups, and R2 is selected from one of C1-C3 halogenated or non-halogenated hydrocarbon groups, One of R3 is selected from one of a hydrogen atom, a halogen atom, a C1-C3 halogenated or non-halogenated alkyl group, and a C2-C3 halogenated or non-halogenated alkenyl group; Preferably, in the first additive A, R1 is selected from one of oxygen atoms and C1 alkylene, and R2 is selected from one of C1-C3 non-halogenated alkylene, One of the following; Preferably, the first additive A is selected from one or more of Compounds 1 to 23: Preferably, the first additive A is one or more of Compound 1, Compound 2, Compound 22, Compound 7, and Compound 23.

5. The wide temperature range sodium ion battery electrolyte according to claim 1, characterized in that In the second additive B, R8 is selected from one of an alkali metal atom, a C1-C3 halogenated alkyl group, a C1-C3 halogenated ester group, a C1-C3 halogenated sulfonyl group, and a C3-C6 silyl group; and R9 is selected from one of a halogen atom, a C1-C3 halogenated hydrocarbon group, and a C1-C3 halogenated hydrocarbonoxy group; Preferably, in the second additive B, R8 is selected from an alkali metal atom and a C1-C3 halogenated alkyl group, and R9 is selected from a halogen element, a C1 halogenated hydrocarbon group, and a C1 halogenated hydrocarbonoxy group; Preferably, the second additive B is selected from one or more of compounds 24 to 48: Preferably, the second additive B is one or more of compound 24, compound 25, compound 30, compound 34, and compound 35.

6. The wide temperature range sodium ion battery electrolyte according to claim 1, characterized in that The electrolyte additive further includes fluorocarbonate; Preferably, the fluorocarbonate is selected from one or more of fluoroethylene carbonate, trifluoromethylethylene carbonate, and bisfluoroethylene carbonate; Preferably, the electrolyte additive further includes fluoroethylene carbonate.

7. The wide temperature range sodium ion battery electrolyte according to claim 1, characterized in that The wide temperature range sodium ion battery electrolyte further includes sodium salt and an organic solvent; Preferably, the sodium salt is selected from one or more of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, sodium difluorooxalatoborate, sodium bis(oxalatoborate), sodium difluorophosphate, sodium nitrate, sodium hexafluoroantimonate, sodium hexafluoroarsenate, sodium difluorobis(oxalatophosphate), and sodium tetrafluorooxalatophosphate; Preferably, the sodium salt is sodium hexafluorophosphate; Further preferably, the mass percentage of the sodium salt in the electrolyte is 5% to 20%; Further preferably, the mass percentage of the sodium salt in the electrolyte is 7.5% to 15%.

8. The wide temperature range sodium ion battery electrolyte according to claim 7, characterized in that: The organic solvent is selected from one or more of cyclic carbonate solvents, chain carbonate solvents, carboxylate solvents, phosphate solvents, ether solvents, and ionic liquids; Preferably, the ether solvent is selected from one or more of ether solvents containing hydroxyl groups, ether solvents containing a single ether bond, and ether solvents containing complex functional groups; Preferably, the complex functional group is selected from one or more of C1-C10 alkoxy, alkenyl, and alkynyl groups; Preferably, the hydroxyl-containing ether solvent is selected from one or more of dipropylene glycol butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, triethylene glycol monomethyl ether, and tetraethylene glycol dimethyl ether; Preferably, the ether solvent containing a single ether bond is selected from one or more of cyclopentyl methyl ether, ethyl ether, and propyl ether; Preferably, the ether solvent containing complex functional groups is selected from one or more of butynediol dipropoxy ether, propargyl ether, and propargyl ether; Preferably, the chain carbonate solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, and ethyl propyl carbonate; Preferably, the carboxylate solvent is selected from one or more of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, methyl isobutyrate, ethyl butyrate, methyl trimethylacetate and ethyl trimethylacetate; Preferably, the cyclic carbonate solvent is selected from one or more of ethylene carbonate, vinylene carbonate, butylene carbonate, propylene carbonate, and pentylene carbonate; Preferably, the phosphate solvent is selected from one or more of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl)phosphite and ethoxy(pentafluoro)cyclotriphosphazene.

9. A wide temperature range sodium ion battery, characterized in that: The invention comprises the wide temperature range sodium ion battery electrolyte according to any one of claims 1 to 8, and further comprises a positive electrode sheet, a negative electrode sheet and a separator.

10. The wide temperature range sodium ion battery according to claim 9, characterized in that: The positive electrode sheet is an aluminum foil sheet coated with a positive electrode active material, and the negative electrode sheet is a copper foil sheet or an aluminum foil sheet coated with a negative electrode active material; Preferably, the positive electrode active material is one of sodium vanadium phosphate, sodium iron phosphate, sodium vanadium fluorophosphate, and a metal layered oxide containing manganese; Preferably, the positive electrode active material is a metal layered oxide containing manganese element, and the general formula of the metal layered oxide containing manganese element is Na x Mn y M z O2, where 0.95 < x ≤ 1.05, 0.01 ≤ y ≤ 0.6, y + z = 1, M represents a transition metal element with an unfilled d electron orbital, specifically including one or more of scandium (Sc), yttrium (Y), lanthanide elements (from lanthanum (La) to lutetium (Lu)), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), copper (Cu), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg); Preferably, M in the manganese-containing positive electrode active material includes at least one of Ni, Fe, and Cu; Preferably, the negative electrode active material is selected from at least one of soft carbon, hard carbon, expanded graphite, phosphorus-carbon composite material, and expanded / hard carbon composite material; Preferably, the negative electrode active material is hard carbon; Preferably, when the positive electrode active material is coated with aluminum foil or the negative electrode active material is coated with aluminum foil or copper foil, a binder and a conductive agent are also used; Preferably, the binder is an oil-based binder, and the binder includes at least one of a thermoplastic resin, an acrylic resin, sodium carboxymethyl cellulose, and styrene butadiene rubber; Preferably, the thermoplastic resin includes at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride, polytetrafluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, a copolymer of tetrafluoroethylene-perfluoroalkyl vinyl ether, a copolymer of ethylene-tetrafluoroethylene, a copolymer of vinylidene fluoride-tetrafluoroethylene, a copolymer of vinylidene fluoride-trifluoroethylene, a copolymer of vinylidene fluoride-trichloroethylene, a copolymer of vinylidene fluoride-fluoroethylene, a copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene and polypropylene; Preferably, the acrylic resin includes at least one of vinyl acrylate resin, methyl acrylate resin, butyl acrylate resin, acrylic styrene resin, acrylate resin, acrylate copolymer resin, acrylic resin, and acrylic emulsion resin; Preferably, the binder is one or more of polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC); Preferably, the conductive agent includes one or more of conductive carbon black (SuperP), conductive carbon balls, conductive graphite, carbon nanotubes (CNTs), conductive carbon fibers, graphene, and reduced graphene oxide; Preferably, the conductive agent is one or more of conductive carbon black (Super P) and carbon nanotubes (CNTs).

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