CN110311171A - A kind of phosphate-based electrolyte with wide operating temperature range and its application - Google Patents

Abstract

The invention belongs to the technical field of electrochemistry, in particular to a phosphate-based electrolyte with a wide working temperature range and an application thereof. The electrolytic solution of the present invention uses phosphoric acid esters and derivatives thereof as solvents, monovalent ion salts (lithium salts, sodium salts, potassium salts), divalent ion salts (zinc salts, calcium salts, magnesium salts), trivalent ion salts Ionic salts (aluminum salts) or quaternary ammonium salts are used as solutes, and additives are also included; phosphate esters and their derivatives have very low melting points, and are still liquid in a low temperature environment of ‑80 °C, and have a high boiling point. It is still stable at ℃. The electrolyte solution provided by the present invention still has high ionic conductivity at relatively low temperature, and still exhibits relatively high safety at relatively high temperature. The working temperature range is -80°C~190°C, and has wide application prospect. The electrolyte solution of the invention can be applied to batteries, capacitors and hybrid capacitors, and the system all exhibits excellent specific capacity, cycle performance, power performance and safety within a wide temperature window.

Description

A kind of phosphate-based electrolyte with wide operating temperature range and its application

technical field

The invention belongs to the technical field of electrochemistry and specifically provides a wide temperature range electrolyte suitable for batteries, capacitors and hybrid batteries/capacitors.

Background technique

Traditional carbonate-based electrolytes mainly use organic solutions that are easily volatile, high melting point, and low flash point as solvents, for example, dimethyl carbonate (melting point 3°C, boiling point 90°C), ethylene carbonate (melting point 34~37°C, Boiling point 243°C), ethyl methyl carbonate (melting point -14°C, boiling point 127°C), diethyl carbonate (melting point -43°C, boiling point 127°C), etc. On the one hand, the high melting point of some carbonate solvents causes the electrolyte to solidify or partially solidify at low temperatures, which greatly reduces the ionic conductivity, thereby limiting the application of batteries in low-temperature fields. For example, the charge and discharge performance of lithium-ion batteries is poor in low temperature environments. Most batteries can only discharge 60-80% of their rated capacity when the temperature is lower than -20°C, and only 30% of their rated capacity can be released at -30--40°C. % or less, and at lower temperatures such as -40 — -60°C, the battery can hardly be discharged. Insufficient low-temperature performance of batteries has become one of the main technical bottlenecks in the development of their applications. On the other hand, the electrolyte is volatile or has a low boiling point, and there is a danger of fire, combustion or even explosion when the battery is working in a high temperature area, which greatly limits the safety performance of the battery. The high-temperature performance and safety of batteries have always been the focus of research. At present, the improvement of low-temperature performance of batteries mainly focuses on physical heating or the use of additives and co-solvents. For example, adding low-melting solvents can effectively reduce the melting point of the electrolyte and improve the low-temperature performance of the battery system. The research on the high-temperature safety performance of batteries is usually to introduce flame retardant additives into the electrolyte, such as halogenated cyclic carbonates, halogenated chain carbonates, alkyl phosphates, fluorinated phosphates, etc. However, few studies have studied the combination of ultra-low temperature and ultra-high temperature.

Phosphate ester organic solvents and their derivatives are non-flammable, have a high boiling point, and are still stable at a high temperature of 200°C, so they are often used as flame retardants and added to conventional electrolytes to make flammable organic solvents The electrolyte becomes flammable or non-flammable electrolyte, which improves the high temperature safety of the electrolyte. In fact, some organic solvents of phosphate esters and their derivatives have lower melting points and are still liquid in a low temperature environment of -80°C, which has obvious advantages over traditionally used carbonate organic solvents. This point has not yet attracted widespread attention, so low-temperature electrolytes using organic solvents of phosphate esters and their derivatives have not been reported.

The invention uses organic solvents of phosphate esters and their derivatives to provide an electrolyte solution with a wide temperature range. The electrolyte solution is based on the electrolyte solution of phosphate ester organic solvents and their derivatives, which can realize a wide temperature range from low temperature to high temperature. The good electrochemical performance in the wide temperature range lays the foundation for the normal operation of the energy storage system in a wide temperature range. The melting points, boiling points and densities of some phosphate esters and their derivative organic solvents are listed in Table 1.

Contents of the invention

The object of the present invention is to provide an electrolyte solution with a wide operating temperature, which can be used in batteries, capacitors and hybrid battery/capacitor systems.

The electrolytic solution with wide working temperature provided by the present invention is based on phosphoric acid esters, that is, organic solvents of phosphoric acid esters and their derivatives are used as solvents to replace traditional carbonate solvents, and monovalent ion salts (lithium salts, sodium salts, etc.) salt, potassium salt), divalent ion salt (zinc salt, calcium salt, magnesium salt), trivalent ion salt (aluminum salt) or quaternary ammonium salt as a solute composition, and also contains additives; of which:

Described phosphate esters and derivatives thereof have the following structural formula:

In the formula, R ₁ , R ₂ , and R ₃ are independently any one of hydrogen, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, and substituted or unsubstituted alkenyl.

In the present invention, the organic solvents of phosphoric acid esters and their derivatives can preferably be trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tripropyl phosphate, dimethyl methyl phosphonate, ethyl phosphoric acid Diethyl ester, tri-tert-butyl phosphate, nitrile methyl diethyl phosphate, tris (2,2,2,-trifluoroethyl) phosphate, tris (2-ethoxyethyl) phosphate one or more of.

In the present invention, the monovalent ion salt includes at least one of lithium salt, sodium salt and potassium salt, specifically selected from lithium trifluoromethanesulfonate, lithium bis(trifluoromethylsulfonyl)imide, Lithium tris(trifluoromethylsulfonyl)methyl, lithium bis(fluorosulfonyl)imide, lithium bisoxalate borate, lithium difluorooxalate borate, LiN(SO ₂ R _F ) ₂ , LiN(SO ₂ F )(SO ₂ R _F ), lithium perchlorate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium hexafluoroarsenate (V), lithium chloride, lithium fluoride, lithium bromide, lithium iodide, lithium sulfate, lithium nitrate, One or more of lithium carbonate, lithium oxalate, lithium formate, lithium acetate, and the corresponding sodium and potassium salts of the above compounds; wherein, R _F = -C _n F _2n+1 , n=1~10.

In the present invention, the divalent ion salt includes at least one of zinc salt, calcium salt and magnesium salt, specifically selected from zinc fluoride, zinc chloride, zinc bromide, zinc iodide, perchloric acid One or more of zinc, zinc tetrafluoroborate, zinc sulfate, zinc nitrate, zinc oxalate, zinc formate, zinc methanesulfonate, zinc trifluoromethanesulfonate and the corresponding calcium and magnesium salts of the above compounds.

In the present invention, the trivalent ion salts include organic salts and inorganic salts of aluminum salts, specifically selected from aluminum chloride, aluminum bromide, aluminum iodide, aluminum sulfate, aluminum nitrate, aluminum silicate, trifluoromethanesulfonate One or more of aluminum tris(trifluorosulfonate)aluminum.

In the present invention, the concentration of the monovalent ion salt, divalent ion salt, trivalent ion salt and quaternary ammonium salt is 0.01-20 mol/L.

In the present invention, the additive is selected from one or more of alkyl quaternary ammonium ions, carbonate compounds, phosphate compounds, borate compounds, sulfite compounds, and sultone compounds.

In the present invention, the content of the additive is 0.1% to 15% of the mass of the electrolyte.

The electrolyte provided by the invention has the advantages of low melting point, high boiling point, low viscosity, good safety, etc., maintains high ion conductivity in a wide working temperature range (-80~190°C), and can improve the performance of the energy storage system. Low temperature performance and high temperature safety issues.

In the present invention, the provided electrolyte solution with wide operating temperature can be applied in batteries, capacitors and hybrid batteries/capacitors.

In the present invention, in the battery system and hybrid battery/capacitor system using the wide working temperature electrolyte, the battery electrode material is selected from intercalation compounds or organic polymer molecules capable of reversibly deintercalating lithium ions as electroactive substances and the above materials of composite materials.

In the present invention, in the capacitor and hybrid battery/capacitor system using the wide working temperature electrolyte, the capacitor electrode material is selected from transition metal oxides, carbon materials, organic polymer molecules, and composite materials of the above materials.

In the present invention, phosphoric acid esters and derivatives thereof have a very low melting point, are still liquid in a low temperature environment of -80°C, and have a high boiling point, and still exist stably at a high temperature of 200°C. Therefore, the electrolyte solution provided by the present invention still has high ionic conductivity at a lower temperature (-80°C), and still exhibits higher safety at a higher temperature (190°C), and exhibits a wider The temperature range (-80°C~190°C) has wide application prospects. The electrolyte solution of the invention can be applied to batteries, capacitors and hybrid capacitors, and the system all exhibits excellent specific capacity, cycle performance, power performance and safety within a wide temperature window.

Detailed ways

In order to make the object of the present invention and technical scheme and advantage clearer, the present invention is described with the following specific examples, but the present invention is not limited to the scope of the provided examples, any non-comprehensible for those skilled in the art Variations or changes that deviate from the gist of the present invention shall fall within the protection scope of the present invention.

Example 1: Under anhydrous and oxygen-free conditions, diethyl ethyl phosphate was used as a solvent, and lithium bis(trifluoromethylsulfonyl)imide was dissolved in it at a concentration of 1 mol/L to prepare a lithium-ion battery electrolyte. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Using lithium manganese oxide (LMO) as the positive electrode material and lithium titanate (LTO) as the negative electrode material, the assembled full battery is charged and discharged at a rate of 1C, and its capacity at room temperature +25°C is ^103mAhg The capacity is 75mAh g ^-1 , and the capacity at a high temperature of 190°C is 106mAh g ^-1 . It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Example 2: Under anhydrous and oxygen-free conditions, diethyl ethyl phosphate was used as a solvent, and sodium bis(trifluoromethylsulfonyl)imide was dissolved in it at a concentration of 1 mol/L to prepare a sodium ion battery electrolyte. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Using sodium vanadium phosphate (NVP) as the positive electrode material and titanium sodium phosphate (NTPO) as the negative electrode material, the assembled full battery is charged and discharged at a rate of 1C, and its capacity at room temperature +25°C is ^110mAhg The capacity is 80mAhg ^-1 , and the capacity at a high temperature of 190°C is 115mAh g ^-1 . It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Example 3: Under anhydrous and oxygen-free conditions, diethyl ethyl phosphate was used as a solvent, and potassium bis(trifluoromethylsulfonyl)imide was dissolved in it at a concentration of 1 mol/L to prepare a potassium ion battery electrolyte. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Using organic polytriphenylamine (PTPAn) as the positive electrode material and organic polyimide (PI) as the negative electrode material, the assembled full battery is charged and discharged at a rate of 1C, and its capacity at room temperature +25°C is 100mAhg ^-1 The capacity at 80°C is 70mAh g ^-1 , and the capacity at high temperature 190°C is 105mAh g ^-1 . It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Example 4: Under anhydrous and oxygen-free conditions, using diethyl ethyl phosphate as a solvent, magnesium bis(trifluoromethylsulfonyl)imide was dissolved in it at a concentration of 1 mol/L to prepare a magnesium ion battery electrolyte. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Using polyimide (PI) as the positive electrode material and metal magnesium (Mg) as the negative electrode material, the assembled full battery is charged and discharged at a rate of 1C, and its capacity at room temperature +25°C is 110mAhg ^-1 , and at a low temperature of -80°C The capacity is 80mAh g ^-1 , and the capacity at a high temperature of 190°C is 115mAh g ^-1 . It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Example 5: Under anhydrous and oxygen-free conditions, diethyl ethyl phosphate was used as a solvent, and zinc bis(trifluoromethylsulfonyl)imide was dissolved in it at a concentration of 1 mol/L to prepare a zinc-ion battery electrolyte. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Using manganese dioxide (MnO ₂ ) as the positive electrode material and metal zinc (Zn) as the negative electrode material, the assembled full battery is charged and discharged at a rate of ^1C . The capacity is 200mAh g ^-1 , and the capacity at a high temperature of 190°C is 295mAh g ^-1 . It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Example 6: Under anhydrous and oxygen-free conditions, diethyl ethyl phosphate was used as a solvent, and aluminum chloride was dissolved therein at a concentration of 1 mol/L to prepare an aluminum ion battery electrolyte. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Using the organic pyrene-4,5,9,10-tetraketone (PTO) as the positive electrode material and metal aluminum (Al) as the negative electrode material, the assembled full battery is charged and discharged at a rate of 1C, and its capacity at room temperature +25°C is 198mAhg ^-1 , the capacity is 150mAh g ^-1 at a low temperature of -80°C, and 205mAh g ^-1 at a high temperature of 190°C. It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Example 7: Under anhydrous and oxygen-free conditions, diethyl ethyl phosphate was used as a solvent to dissolve quaternary ammonium tetrafluoroborate at a concentration of 1 mol/L to prepare an electrolyte for supercapacitors. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Activated carbon (AC) is used as positive and negative electrode materials, and the assembled capacitor is charged and discharged at a current density of 1A/g. Its capacity at room temperature +25°C is 298Fg ^-1 , at low temperature -80°C it is 260Fg ^-1 The capacity at 190°C is 305Fg ^-1 . It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Example 8: Under anhydrous and oxygen-free conditions, diethyl ethyl phosphate was used as a solvent, and lithium hexafluorophosphate was dissolved therein at a concentration of 1 mol/L to prepare an electrolyte solution for a hybrid battery/capacitor. The electrolyte can withstand -80°C at low temperature and 190°C at high temperature. Using lithium manganate (LMO) as the positive electrode material and activated carbon (AC) as the negative electrode material, the assembled hybrid battery/capacitor system can be charged and discharged at a rate of 1C. Its capacity at room temperature +25°C is 103mAhg ^-1 The capacity at ℃ is 75mAhg ^-1 , and the capacity at high temperature 190℃ is 106mAh g ^-1 . It exhibits excellent electrochemical performance in a wide temperature range (-80~190°C), see Table 2.

Table 1 Molecular formula, melting point, boiling point and density of some organic solvents of phosphate esters and their derivatives

Table 2 Electrochemical performance of batteries, capacitors and hybrid battery/capacitor systems based on wide operating temperature range electrolytes

Claims (9)

1. a kind of phosphate-based electrolyte of wide operating temperature range, which is characterized in that organic with phosphoric acid ester and its derivative Solvent is formed as solvent using monovalent ion salt, divalent ion salt, trivalent ion salt or quaternary ammonium salt as solute, and includes Additive；Wherein, phosphoric acid ester and its derivative have following structure formula:

In formula, R₁、R₂、R₃It is each independently respectively hydrogen, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted virtue Any one of base, substituted or unsubstituted alkenyl.

2. the phosphate-based electrolyte of wide operating temperature range according to claim 1, which is characterized in that the monovalence Ion salt is at least one of lithium salts, sodium salt and sylvite, is chosen in particular from trifluoromethyl sulfonic acid lithium, bis- (trimethyl fluoride sulfonyls) Asia Amine lithium, three (trimethyl fluoride sulfonyl) lithium methides, bis- (fluorine sulphonyl) imine lithiums, biethyl diacid lithium borate, difluorine oxalic acid boracic acid lithium, LiN(SO₂R_F)₂、LiN(SO₂F)(SO₂R_F), lithium perchlorate, LiBF4, lithium hexafluoro phosphate, hexafluoro close arsenic (V) sour lithium, chlorine Change lithium, lithium fluoride, lithium bromide, lithium iodide, lithium sulfate, lithium nitrate, lithium carbonate, lithium oxalate, lithium formate, lithium acetate and above-mentionedization Close one or more of the corresponding sodium salt of object and sylvite；Wherein, R_F = -C_nF_2n+1, n=1 ~ 10.

3. the phosphate-based electrolyte of wide operating temperature range according to claim 1, which is characterized in that the divalent Ion salt is at least one of zinc salt, calcium salt and magnesium salts, be chosen in particular from selected from zinc fluoride, zinc chloride, zinc bromide, zinc iodide, Zinc perchlorate, tetrafluoro boric acid zinc, zinc sulfate, zinc nitrate, zinc oxalate, zinc formate, zine methqne-sulfonate, trifluoromethanesulfonic acid zinc and on State one or more of the corresponding calcium salt of compound and magnesium salts.

4. the phosphate-based electrolyte of wide operating temperature range according to claim 1, which is characterized in that the trivalent Ion salt is the organic salt or inorganic salts of aluminium salt, is chosen in particular from aluminium chloride, aluminium bromide, silver iodide, aluminum sulfate, aluminum nitrate, silicic acid Aluminium, trifluoromethanesulfonic acid aluminium, three (three fluosulfonic acid) aluminium.

5. the phosphate-based electrolyte of wide operating temperature range described in one of -4 according to claim 1, which is characterized in that institute The concentration for stating solute is 0.01 ~ 20 mol/L.

6. the phosphate-based electrolyte of wide operating temperature range described in one of -4 according to claim 1, which is characterized in that institute It states additive and is selected from quaternary ammonium alkyl radical ion, carbonats compound, phosphate compounds, boric acid ester compound, sulfurous Acid esters compound, sultones class compound；The content of additive is the 0.1% ~ 15% of the quality of electrolyte.

7. according to claim 1 the phosphate-based electrolyte of wide operating temperature range described in one of -6 battery, capacitor or Application in hybrid type battery/capacitor.

8. application according to claim 7, which is characterized in that the electroactive material of battery electrode material is selected from can be reversible The inlaid scheme or organic polymer molecules of deintercalate lithium ions and the composite material of above-mentioned material.

9. application according to claim 7, which is characterized in that capacitor electrode material is selected from transition metal oxide, carbon The composite material of material, organic polymer molecules and above-mentioned material.