阅读说明：本技术 钠离子电解液、二次电池及制备方法和应用 (Sodium ion electrolyte, secondary cell and preparation method and application ) 是由 喻妍 马紫峰 车海英 邓永红 于 2019-07-03 设计创作，主要内容包括：本发明公开了一种钠离子电解液、二次电池及制备方法和应用。该电解液包括基础电解液和添加剂,所述基础电解液包括钠盐和阻燃溶剂；所述阻燃溶剂包括磷酸酯和氟代醚；所述添加剂包括含氟添加剂；所述钠盐相对于所述基础电解液的浓度为1～2mol/L；所述钠盐相对于所述磷酸酯的浓度为1.5～3mol/L；所述磷酸酯和所述氟代醚的体积比为1:1～2:1；所述添加剂的含量占所述基础电解液的质量百分比为大于0,小于等于5wt％。本发明的电解液制备的钠离子电池具有热稳定性好,可形成稳定的SEI膜而阻碍电极与电解液之间发生反应,具有与以碳酸酯为溶剂的电解液相当的充放电性能,制造成本低。(The invention discloses a kind of sodium ion electrolyte, secondary cell and preparation method and application.The electrolyte includes basic electrolyte and additive, and the basic electrolyte includes sodium salt and fire-retardant solvent；The fire-retardant solvent includes phosphate and fluoro-ether；The additive includes fluorochemical additive；The sodium salt is 1~2mol/L relative to the concentration of the basic electrolyte；The sodium salt is 1.5~3mol/L relative to the concentration of the phosphate；The volume ratio of the phosphate and the fluoro-ether is 1:1~2:1；The mass percent that the content of the additive accounts for the basic electrolyte is to be less than or equal to 5wt% greater than 0.The sodium-ion battery of electrolyte preparation of the invention has thermal stability good, can form stable SEI film and react between impeded electrode and electrolyte, have with using carbonic ester as the comparable charge-discharge performance of the electrolyte of solvent, manufacturing cost is low.)

1. a kind of electrolyte, which is characterized in that it includes basic electrolyte and additive, the basic electrolyte include sodium salt and Fire-retardant solvent；The fire-retardant solvent includes phosphate and fluoro-ether；The additive includes fluorochemical additive；The sodium salt is opposite In the basic electrolyte concentration be 1~2mol/L；The sodium salt is 1.5~3mol/ relative to the concentration of the phosphate L；The volume ratio of the phosphate and the fluoro-ether is 1:1~2:1；The content of the additive accounts for the basic electrolyte Mass percent is to be less than or equal to 5wt% greater than 0.

2. electrolyte as described in claim 1, which is characterized in that the sodium salt is sodium hexafluoro phosphate and/or sodium perchlorate；

And/or the phosphate is trimethyl phosphate, triethyl phosphate, tricresyl phosphate, triphenyl phosphate, methyl acid phosphate One of dimethyl ester and ethyl phosphonic acid diethylester are a variety of；

And/or the fluoro-ether be 1,1,2,2- tetra- fluoro ethyl -2,2,3,3- tetrafluoro propyl ethers, 1,1,2,2- tetra- fluoro ethyl -2, One of 2,2- trifluoroethyl ether and 2H- perfluor (5- methyl -3,6- dioxanonane) are a variety of；

And/or the fluorochemical additive is fluorinated ethylene carbonate；

And/or the sodium salt is 2.25mol/L relative to the concentration of the phosphate；

And/or the sodium salt is 1.5mol/L relative to the concentration of the basic electrolyte；

And/or the volume ratio of the phosphate and the fluoro-ether is 2:1；

And/or it is 2wt% that the content of the additive, which accounts for the mass percent of the basic electrolyte,.

3. electrolyte as claimed in claim 2, which is characterized in that the trimethyl phosphate is anhydrous grade trimethyl phosphate.

4. electrolyte as described in claim 1, which is characterized in that it is by the sodium salt, the phosphate, the fluorine For ether and the additive composition.

5. a kind of preparation method of electrolyte according to any one of claims 1-4 comprising following step: by the basis Electrolyte and the additive are uniformly mixed.

6. preparation method as claimed in claim 5, which is characterized in that the mixing carries out under an inert atmosphere, and described is lazy Property atmosphere is preferably argon gas.

7. a kind of application of electrolyte according to any one of claims 1-4 in the secondary battery.

8. the use as claimed in claim 7, which is characterized in that the secondary cell is sodium rechargeable battery.

9. a kind of secondary cell, which is characterized in that its electrolyte is electrolyte according to any one of claims 1-4.

10. secondary cell as claimed in claim 9, which is characterized in that the positive electrode of the secondary cell is stratiform gold Belong to oxide, preferably NaNi₁/₃Fe₁/₃Mn₁/₃O₃；

And/or the negative electrode material of the secondary cell is Carbon materials, preferably hard carbon.

Technical field

The present invention relates to a kind of sodium ion electrolyte, secondary cell and preparation method and application.

Background technique

In recent years, since sodium is resourceful, cost is relatively low, and future can be applied in extensive energy storage, becomes present battery The new hot spot of research.With application of the battery in mobile phone, computer, electric car and extensive energy storage, battery system safety Problem becomes the emphasis of industry concern.Therefore, the safety issue of sodium ion electrolyte, the emphasis for also receiving researchers close Note.

The thermal stability of electrolyte system and the low flammability of electrolyte solvent are to influence the principal element of battery security. As it can be seen that thinking the safety of raising battery, the electrolyte system for developing high security is most effective measure.For example, battery is warm Beginning out of control is the decomposition due to SEI film, thus cause reacting between electrode material and electrolyte and with binder it Between reaction, these reactions are all related with electrolyte.The thermal stability and low flammability of electrolyte depend primarily in electrolyte Solvent, salt and additive composition, it can from the use three of the selection of sodium salt, the selection of dicyandiamide solution and additive The electrolyte system of high security is designed in direction.

Currently, this field electrolyte Conventional solvents are carbonate-based solvent, usually addition is hindered containing phosphorus type flame retardant, nitrogenous class Agent and composite flame-retardant agent are fired to realize low flammability, but the fire retardant of high concentration is needed in electrolyte to realize low flammability. However, high concentration of fire retardant can cause the problems such as mutually separation and the loss battery performance of electrolyte itself, even with height Concentration salt can solve the above problems, but high salt concentration is not only at high cost, and electrolysis fluid viscosity is big, lead to flame retardant property and electrochemistry The problem of can taking into account, it is difficult practical application.In the electrolyte that carbonic ester (PC) is solvent, the thermal stability of sodium salt are as follows: NaClO₄>NaPF₆> NaTFSI, but thermal behavior of the different salts in different solvents is different.

It proposes a kind of electrolyte in Chinese patent CN103827416A to be used in lithium ion battery, with carbon in the electrolyte Acid esters is solvent, with phosphazene compound, fluorated solvent and organophosphorus ester or organic bony acid esters for fire-retardant cosolvent or addition Agent.But the discharge capacity of its electrolyte is unsatisfactory, and cycle performance of battery is poor.

It is proposed in Chinese patent CN2017104877213 using LiBOB as lithium salts, lactone and fluorinated ether are as solvent Electrolyte in lithium ion battery.But lactone is also a kind of combustible solvent, and thermal stability is poor in use, is deposited In security risk.

As it can be seen that in the prior art, select to add a large amount of fire retardants for the defect for overcoming carbonates electrolyte inflammable, but Cause chemical property to decline again, such as by improve salinity solve the problems, such as low flammability and electrochemistry can take into account and It is big to will lead to electrolysis fluid viscosity；Therefore, searching can overcome above-mentioned difficulties, and meet that electrolyte thermal stability is good, and surface SEI film is not It easily decomposes, the electrolyte that can be reacted between impeded electrode and electrolyte is this field problem urgently to be resolved.

Summary of the invention

The present invention is practical, and the technical problem to be solved is that be the electrolyte of solvent to overcome carbonic ester in the prior art Thermal stability is poor, SEI film easily decomposes, and can react between electrode and electrolyte, and a large amount of fire retardants, which are added, leads to electricity The problem of chemical property declines provides a kind of sodium ion electrolyte, secondary cell and preparation method and application.With of the invention Electrolyte preparation sodium-ion battery have thermal stability it is good, stable SEI film can be formed and between impeded electrode and electrolyte It reacts, has with using carbonic ester as the comparable charge-discharge performance of the electrolyte of solvent, manufacturing cost is low.

Inventor's discovery uses phosphate and fluoro-ether as fire-retardant solvent, using fluorochemical additive, compared with low salt concn Under conditions of, the electrolyte with desired electrochemical performance is prepared, electrochemical properties are suitable with carbonates electrolyte, and are electrolysed Liquid is nonflammable；Meanwhile stable SEI film can be formed, it is chemically reacted between impeded electrode and electrolyte, there is thermostabilization Property.The application electrolyte takes into account low flammability energy and thermal stability, is high safety type electrolyte.

The present invention solves above-mentioned technical problem by the following technical programs.

The present invention provides a kind of electrolyte comprising basic electrolyte and additive, the basic electrolyte include sodium Salt and fire-retardant solvent；

The fire-retardant solvent includes phosphate and fluoro-ether；The additive includes fluorochemical additive；The sodium salt is opposite In the basic electrolyte concentration be 1~2mol/L；The sodium salt is 1.5~3mol/ relative to the concentration of the phosphate L；The volume ratio of the phosphate and the fluoro-ether is 1:1~2:1；The content of the additive accounts for the basic electrolyte Mass percent is to be less than or equal to 5wt% greater than 0.

In the present invention, the sodium salt can be conventional for this field, preferably sodium hexafluoro phosphate and/or sodium perchlorate.

In the present invention, the phosphate is preferably trimethyl phosphate, triethyl phosphate, tricresyl phosphate, tricresyl phosphate One of phenyl ester, methyl-phosphoric acid dimethyl ester and ethyl phosphonic acid diethylester are a variety of.

In the present invention, the trimethyl phosphate is preferably anhydrous grade trimethyl phosphate.

In the present invention, the fluoro-ether is preferably 1,1,2,2- tetra- fluoro ethyl -2,2,3,3- tetrafluoro propyl ethers, 1, and 1,2, One of tetra- fluoro ethyl -2,2,2- trifluoroethyl ether of 2- and 2H- perfluor (5- methyl -3,6- dioxanonane) are a variety of.

In the present invention, the fluorochemical additive is preferably fluorinated ethylene carbonate.In the present invention, the sodium salt relative to The concentration of the phosphate is preferably 2.25mol/L.

In the present invention, the sodium salt is preferably 1.5mol/L relative to the concentration of the basic electrolyte.

In the present invention, the volume ratio of the phosphate and the fluoro-ether is preferably 2:1.

In the present invention, the mass percent that the content of the additive accounts for the basic electrolyte is preferably 2wt%.

In preferred embodiment of the present invention, the electrolyte is by the sodium salt, the phosphate, the fluoro Ether and additive composition.

The present invention also provides a kind of preparation methods of electrolyte comprising following step: the basis is electrolysed Liquid and the additive are uniformly mixed.

In the present invention, preferably, the mixing carries out under an inert atmosphere.For example, the mixing can in glove box into Row.

Wherein, the inert atmosphere is preferably argon gas.

The present invention also provides a kind of application of above-mentioned electrolyte in the secondary battery.

In the present invention, the secondary cell can be sodium rechargeable battery.

The present invention also provides a kind of secondary cell, electrolyte is above-mentioned electrolyte.

In the present invention, the positive electrode of the secondary cell can be conventional for this field, preferably layered metal oxide, It is more preferably NaNi₁/₃Fe₁/₃Mn₁/₃O₃(NFM)。

In the present invention, the negative electrode material of the secondary cell can be conventional for this field, preferably Carbon materials, more preferably For hard carbon (HC).

On the basis of common knowledge of the art, above-mentioned each optimum condition, can any combination to get each preferable reality of the present invention Apply example.

The reagents and materials used in the present invention are commercially available.

The positive effect of the present invention is that:

Electrolyte of the invention has thermal stability and low flammability, using low concentration of salt, overcomes because big Amount the drawbacks of causing electrolyte flame-retardant performance and electrochemistry that can take into account using fire retardant, have and be molten with carbonic ester The comparable charge-discharge performance of the electrolyte of agent；And stable SEI film can be formed and reacted between impeded electrode and electrolyte, The good thermal stability of electrolyte is a kind of highly-safe electrolyte；The sodium-ion battery prepared with electrolyte of the invention With very high safety, and sodium is resourceful, and manufacturing cost is low in large-scale commercial process, is suitable for industrial metaplasia It produces.

Detailed description of the invention

Fig. 1 is 1 electrolyte combustibility test comparison chart of the embodiment of the present invention 1 and comparative example.

Fig. 2 is the cycle performance using the NFM/Na battery of 1 electrolyte of the embodiment of the present invention 1, embodiment 2 and comparative example.

Fig. 3 is the first circle charge and discharge using the NFM/Na battery of 1 electrolyte of the embodiment of the present invention 1, embodiment 2 and comparative example Curve.

Fig. 4 is following using the NFM/Na battery of the embodiment of the present invention 3,4 electrolyte of embodiment 4, comparative example 3 and comparative example Ring performance.

Fig. 5 is the first circle charging and discharging curve using 6 electrolyte HC/Na battery of the embodiment of the present invention 1 and comparative example.

Fig. 6 is the first circle charging and discharging curve using 5 electrolyte HC/Na battery of the embodiment of the present invention 5 and comparative example.

Specific embodiment

The present invention is further illustrated below by the mode of embodiment, but does not therefore limit the present invention to the reality It applies among a range.In the following examples, the experimental methods for specific conditions are not specified, according to conventional methods and conditions, or according to quotient The selection of product specification.

In the following example and comparative example, the preparation method of electrolyte includes the following steps, by the basic electrolyte and The additive is uniformly mixed.All be blended in the glove box full of argon gas carries out.