CN-122025809-A - Low-temperature electrolyte of sodium ion battery, sodium ion battery and activation method of sodium ion battery

CN122025809ACN 122025809 ACN122025809 ACN 122025809ACN-122025809-A

Abstract

The invention provides a low-temperature electrolyte of a sodium ion battery, the sodium ion battery and an activation method thereof, wherein the low-temperature electrolyte of the sodium ion battery comprises sodium salt, an interface modification additive, a sodium guide framework additive and an organic solvent, the mass ratio of the interface modification additive to the sodium guide framework additive is 1:0.5-2, the concentration of the sodium salt is 0.8-1.5M, the low-temperature electrolyte of the sodium ion battery provided by the invention uses a dual-functional additive system, a silicon-containing compound is used as the interface modification additive, stable SEI films rich in siloxane and sodium fluoride can be formed by preferential reduction on the surface of a negative electrode, an MOF material is used as the sodium guide framework additive, an ordered channel is provided for sodium ion transmission by utilizing a regular pore channel structure of the MOF material, and the formed electrolyte has the advantage of high ion conductivity and is convenient for industrialized popularization.

Inventors

ZHU YAFEI
ZHAO WENWEN
Dong Sixiao
LIAN FEI

Assignees

兆钠新能源科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260126

Claims (10)

1. The low-temperature electrolyte of the sodium ion battery is characterized by comprising sodium salt, an interface type modification additive, a sodium guide framework additive and an organic solvent, wherein the mass ratio of the interface type modification additive to the sodium guide framework additive is 1:0.5-2, and the concentration of the sodium salt is 0.8-1.5M.
2. The sodium ion battery low temperature electrolyte of claim 1, wherein the interface modification additives are tris (trimethylsilane) phosphate and/or tris (trimethylsilane) phosphite.
3. The sodium ion battery low temperature electrolyte of claim 1, wherein the sodium-conducting backbone additive comprises ZIF-8 and/or UIO-66.
4. The low-temperature electrolyte for sodium ion batteries according to claim 3, wherein the particle size of the sodium-conducting framework additive is 50-200 nm.
5. The low-temperature electrolyte of a sodium ion battery according to claim 1, wherein the mass of the interface modification additive and the sodium guide skeleton additive accounts for 1% -5% of the total mass of the low-temperature electrolyte of the sodium ion battery.
6. The sodium ion battery low temperature electrolyte of claim 1, wherein the sodium salt comprises any one or a combination of at least two of NaPF 6 , naFSI, or NaClO 4 .
7. The low-temperature electrolyte of a sodium ion battery according to claim 1, wherein the organic solvent comprises a mixture of ethylene carbonate, propylene carbonate, fluoroethylene carbonate and ethylmethyl carbonate, and the volume ratio of the ethylene carbonate, the propylene carbonate, the fluoroethylene carbonate and the ethylmethyl carbonate is (2-4): 1-3): 0.5-2): 3-5.
8. A sodium ion battery, characterized in that the sodium ion battery comprises the sodium ion battery low-temperature electrolyte as claimed in any one of claims 1 to 7.
9. The method of activating a sodium ion battery according to claim 8, wherein the method of activating comprises: (1) The electrolyte of the sodium ion battery at low temperature is infiltrated into the electrode to generate interface reaction; (2) Sequentially performing first-stage charging and first-stage discharging in a medium-voltage environment, and circulating the first-stage charging and the first-stage discharging for 1-3 times to obtain an SEI film; (3) And continuously carrying out second-stage charging and second-stage discharging at low temperature, and circulating the second-stage charging and second-stage discharging for 2-5 times to obtain the sodium ion battery.
10. The activation method according to claim 9, wherein the low temperature in step (1) is-10 to 0 ℃, and the time of infiltration is 12 to 48 hours; In the step (2), the temperature of the medium-voltage environment is 10-25 ℃, the multiplying power of the first-stage charging is 0.05-0.2 ℃, the first-stage charging is carried out until the voltage is 2-3V, the multiplying power of the first-stage discharging is 0.02-0.1 ℃, and the first-stage discharging is carried out until the voltage is 1-2V; In the step (3), the low temperature is-20-0 ℃, the multiplying power of the second stage of charging is 0.1-0.5 ℃, the second stage of charging is charged to 3-3.8V, the multiplying power of the second stage of discharging is 0.1-0.5 ℃, and the second stage of discharging is discharged to 1.5-2.5V.

Description

Low-temperature electrolyte of sodium ion battery, sodium ion battery and activation method of sodium ion battery Technical Field The invention relates to the technical field of batteries, in particular to a low-temperature electrolyte of a sodium ion battery, the sodium ion battery and an activation method thereof. Background The sodium ion battery has wide prospect in the field of large-scale energy storage due to the advantages of rich resources, low cost and the like. However, the problem of sharp degradation of performance in low temperature environments severely limits practical applications. In the prior art, the method for improving the low-temperature performance of the sodium ion battery mainly comprises electrolyte optimization, such as film forming additive addition, low-viscosity solvent use and the like. In CN120527452A, triisopropyl silicone triflate is used as single additive, and triphenylphosphine bromide derivative is used as additive for Hunan sodium new energy. Most of these schemes rely on a single additive, which makes it difficult to combine interfacial stability and ion transport efficiency. The material modification is that sodium is reduced in internal resistance through the cooperative design of a framework supporting material and a conductive filler, and Na 2Ti3O7 -loaded nitrogen-doped carbon nanofiber anode material is developed by Hunan cubic new energy. These methods are complex and costly. The activation process is optimized by a multi-stage gradient formation method such as Li Wei and the like, wherein the multi-stage gradient formation method comprises pre-passivation, an SEI film construction period and a stabilization period, and the circulation stability is improved by using Jiangsu Jichu intelligent technology through the synergistic effect of positive and negative active substances. Most of these processes are complex and time consuming. CN120914341A discloses a sodium ion battery electrolyte and a preparation method thereof, wherein the electrolyte comprises sodium salt, a composite solvent, an additive and an auxiliary agent, the sodium salt is compounded by sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethanesulfonyl) imide and modified sodium bisoxalato borate, the composite solvent is sulfolane, 1, 3-propylene glycol dimethyl ether, dimethyl carbonate, fluoroethylene carbonate and ethyl acetate, the additive is modified 1, 3-propane sultone, trimethyl phosphate and hydroquinone dimethyl ether, and the auxiliary agent is nano ZIF-8. The electrolyte sodium bisoxalato borate is modified by hydrogen peroxide to have high-efficiency hydrofluoric acid resistance, and meanwhile, the sodium salt and the auxiliary agent form synergistic effect by utilizing the auxiliary agent of nano ZIF-8, so that hydrofluoric acid generated by the reaction of fluorine-containing sodium salt in the electrolyte and moisture can be removed in a targeted manner, the damage of the hydrofluoric acid to a negative electrode SEI film is avoided, and the cycle life of a sodium ion battery is further prolonged. But sulfolane and 1, 3-propylene glycol dimethyl ether belong to high-viscosity solvents, and the electrolyte has poor fluidity at low temperature, so that ion conduction is limited, and the technology has unsatisfactory performance in a low-temperature environment. CN120300127a discloses a composite positive electrode of sodium ion battery, a preparation method and a prepared secondary sodium ion battery, wherein the composite positive electrode of sodium ion battery sequentially comprises a collector, a layered oxide layer and an MOF layer, and when the composite positive electrode of sodium ion battery is prepared, the layered oxide layer and the MOF layer are respectively formed by adopting a dry method. According to the method, the MOF layer is directly coated on the surface of the manganese-based layered oxide layer, so that the stability of the layered oxide in air is improved, the layered oxide is inhibited from being corroded by electrolyte, and through adding a proper sodium ion conductor and an electron conductor into the MOF layer, the transmission of sodium ions is promoted, meanwhile, gas products and solid byproducts of side reactions of a battery are adsorbed, and the sodium ion conductor and the electron conductor in the MOF layer can ensure the rapid transmission of sodium ions and electrons and improve the activity of an anode, so that the higher capacity, the more excellent rate performance and the longer cycle life of the battery are realized. However, at low temperatures, the MOF layer may change from a channel that facilitates ion and electron transport to a porous barrier that needs to overcome additional resistance due to poor electrolyte wettability and reduced conductivity itself, and thus this method cannot guarantee the performance of the electrolyte in low temperature environments. In a combined way, the prior art has the following limitation that