阅读说明：本技术 一种适用于钾离子电池的浓缩电解液体系 (Concentrated electrolyte system suitable for potassium ion battery ) 是由 孙传福 张如定 于 2018-05-31 设计创作，主要内容包括：本发明提供了一种适用于钾离子电池的浓缩电解液体系。所述浓缩电解液体系包括钾盐和溶剂；其中钾盐的摩尔浓度为大于等于2mol/L,将该浓缩电解液体系直接用于钾离子电池中时,可使电池电极材料(包括钾金属)发挥出优异的循环和倍率性能以及接近100％的充放电库伦效率；该浓缩电解液体系配方组成简单,便于规模化生产,并可直接用于钾离子电池等电化学储能领域。将浓缩电解液体系与铋负极或对苯醌有机负极或类普鲁士白(K<Sub>1.68</Sub>Fe<Sub>1.09</Sub>Fe(CN)<Sub>6</Sub>·2.1H<Sub>2</Sub>O)正极组合直接用于组装钾离子电池,所得电池具有稳定性高,循环性能好,充放电库伦效率高的优点。(The invention provides a concentrated electrolyte system suitable for a potassium ion battery, which comprises potassium salt and a solvent, wherein the molar concentration of the potassium salt is more than or equal to 2mol/L, when the concentrated electrolyte system is directly used in the potassium ion battery, a battery electrode material (comprising potassium metal) can exert excellent cycle and rate performance and charge-discharge coulombic efficiency close to 100%, the concentrated electrolyte system has simple formula composition, is convenient for large-scale production, and can be directly used in the field of electrochemical energy storage such as the potassium ion battery, and the concentrated electrolyte system is directly used for assembling the potassium ion battery by combining with a bismuth cathode or a p-benzoquinone organic cathode or a Prussian-like white (K 1.68 Fe 1.09 Fe (CN) 6 .2.1H 2 O) anode.)

1. A concentrated electrolyte system suitable for use in a potassium ion battery, the concentrated electrolyte system comprising a potassium salt and a solvent; wherein the molar concentration of the potassium salt is more than or equal to 2 mol/L.

2. The electrolyte system of claim 1 wherein the concentrated electrolyte system is comprised of a potassium salt and a solvent.

3. the electrolyte system of claim 1 or 2, wherein the potassium salt is at least one of potassium bis (trifluoromethylsulfonyl) imide, potassium bis (fluorosulfonyl) imide, potassium nitrate, potassium fluoroborate, potassium hexafluorophosphate, potassium perchlorate.

4. The electrolyte system of any of claims 1-3, wherein the solvent is at least one of dimethyl ether, diglyme, ethylene glycol dimethyl ether, ethylene carbonate, propylene carbonate, dimethyl carbonate, fluoroethylene carbonate, diethyl carbonate, and methyl ethylene carbonate.

5. The electrolyte system of any one of claims 1-4, wherein the molar concentration of the potassium salt in the concentrated electrolyte system is 3mol/L or more.

6. A method of making a concentrated electrolyte system as claimed in any one of claims 1 to 5, said method comprising the steps of:

and fully mixing the solvent and the potassium salt, and preparing the concentrated electrolyte system after the potassium salt is completely dissolved in the solvent, wherein the molar concentration of the potassium salt in the concentrated electrolyte system is more than or equal to 2 mol/L.

7. A potassium ion battery comprising the concentrated electrolyte system of any of claims 1-4.

8. The battery of claim 7, wherein the potassium ion battery further comprises a negative electrode and a positive electrode.

9. The battery of claim 8, wherein the negative electrode is a bismuth negative electrode or a p-benzoquinone negative electrode.

10. The cell of claim 8 wherein the positive electrode is a Prussian-like white (K _1.68 Fe _1.09 Fe (CN) ₆ -2.1H ₂ O) positive electrode.

Technical Field

The invention belongs to the technical field of high-energy batteries, and particularly relates to a concentrated electrolyte system suitable for a potassium ion battery.

Background

Lithium ion batteries have enjoyed great success in portable electronic devices and electric vehicles. However, the inherent disadvantages of scarce lithium resources, uneven distribution, high cost and the like limit the further application of the lithium battery; especially in the large-scale electricity storage field such as low-cost smart grid, the challenge faced by lithium ion batteries is more and more prominent. Development of alternative secondary battery technology is considered as an effective solution to the above problems. The advantages of rich potassium resource, low cost, higher battery voltage and the like of the potassium ion secondary battery are considered to be one of the keys of the future large-scale low-cost electrochemical energy storage technology, and the development of the potassium ion battery with stable cycle performance has great industrial application value.

Similar to lithium ion battery electrolyte, the main formula of the current potassium ion battery electrolyte still consists of a conventional electrolyte system in which potassium salt is dissolved in organic solvents such as carbonates, ethers and the like. However, batteries assembled by combining these conventional electrolytes with electrode materials of potassium ion batteries or potassium metals generally face various problems of poor cycling stability and rate capability, unstable SEI film structures on the surfaces of the electrode materials or potassium metals, low charging and discharging coulombic efficiency and the like in the charging and discharging processes, so that the practical application of the batteries in the potassium ion batteries is difficult to realize. Therefore, developing a universal electrolyte system, effectively improving the cycling stability and rate capability of the electrode material (including the potassium metal cathode) of the potassium ion battery by a simple method, improving the coulombic efficiency of the battery and the like has very important significance. Compared with a conventional electrolyte system, the preparation method disclosed by the invention has the advantages that the formula of the concentrated electrolyte containing the sylvite is adopted, the stability of the SEI film structure on the surface of the electrode material is improved, the cycle life of the electrode material can be effectively prolonged, and the electrode material has excellent electrochemical performances such as excellent cycle and rate stability, high charging and discharging coulombic efficiency and the like.

disclosure of Invention

The invention aims to overcome the defect that the electrolyte of the existing potassium ion battery is not matched with the electrode material (comprising potassium metal); the problems of poor cycle performance, low reversible capacity, low charging and discharging coulombic efficiency and the like of the electrode material of the potassium ion battery in the conventional electrolyte at present are solved; the universal concentrated electrolyte system suitable for the potassium ion battery is provided, and can enable an electrode material to exert excellent cycle and rate performance and high charging and discharging coulombic efficiency when being used in the potassium ion battery.

In order to solve the problems, the invention is realized by the following technical scheme:

A concentrated electrolyte system suitable for use in a potassium ion battery, the concentrated electrolyte system comprising a potassium salt and a solvent; wherein the molar concentration of the potassium salt is more than or equal to 2 mol/L.

According to an embodiment of the invention, the concentrated electrolyte system consists of a potassium salt and a solvent.

according to an embodiment of the present invention, the potassium salt is at least one of potassium bis (trifluoromethylsulfonyl) imide, potassium bis (fluorosulfonyl) imide, potassium nitrate, potassium fluoroborate, potassium hexafluorophosphate, potassium perchlorate;

according to an embodiment of the present invention, the solvent is at least one of dimethyl ether, diglyme, ethylene glycol dimethyl ether, ethylene carbonate, propylene carbonate, dimethyl carbonate, fluoroethylene carbonate, diethyl carbonate, and methyl ethylene carbonate.

According to an embodiment of the present invention, the molar concentration of the potassium salt in the concentrated electrolyte system is 3mol/L or more. The upper limit of the molar concentration of the potassium salt in the concentrated electrolyte solution system is not particularly limited, and the concentrated electrolyte solution system may be a saturated solution or a supersaturated solution. Those skilled in the art can make reasonable selections according to specific use cases.

The invention also provides a preparation method of the concentrated electrolyte system, which comprises the following steps:

And fully mixing the solvent and the potassium salt, and preparing the concentrated electrolyte system after the potassium salt is completely dissolved in the solvent, wherein the molar concentration of the potassium salt is more than or equal to 2 mol/L.

According to an embodiment of the invention, the potassium salt is dried in a glove box vacuum oven at 80-120 ℃ for 24-48 hours before use to remove water from the potassium salt.

The invention also provides a potassium ion battery which comprises the concentrated electrolyte system.

According to an embodiment of the present invention, the potassium ion battery further comprises a negative electrode and a positive electrode.

According to the embodiment of the invention, the negative electrode is just a conventional negative electrode material suitable for a potassium ion battery, and is exemplarily a bismuth negative electrode or a p-benzoquinone negative electrode.

According to the embodiment of the invention, the positive electrode is just applicable to the conventional positive electrode material in the potassium ion battery, and is exemplarily a prussian-like white (K _1.68 Fe _1.09 Fe (cn) ₆ · 2.1H ₂ O) positive electrode.

The potassium ion battery provided by the invention uses the concentrated electrolyte system. The concentrated electrolyte system has high electrochemical reduction and oxidation resistance, so that a Solid Electrolyte Interface (SEI) film with a stable structure can be formed on the surface of an electrode material in an electrochemical circulation process, the surface of the electrode material can be effectively passivated, rapid transmission and diffusion transfer of potassium ions are facilitated, and the electrode material (including potassium metal) can finally exert excellent electrochemical performance.

The invention has the beneficial effects that:

The concentrated electrolyte system has simple formula, is convenient for large-scale production, and can be directly used in the field of electrochemical energy storage such as potassium ion batteries, for example, the concentrated electrolyte system is directly combined with a bismuth cathode or a p-benzoquinone organic cathode or a Prussian-like white (K _1.68 Fe _1.09 Fe (CN) ₆.2.1H ₂ O) anode to be used for assembling the potassium ion battery, and the obtained battery has the advantages of high stability, good cycle performance and high charging and discharging coulombic efficiency.

Drawings

FIG. 1 is a cyclic voltammetry curve of a bismuth negative electrode potassium ion secondary battery obtained in example 1 of the present invention;

FIG. 2 is a charge-discharge curve diagram of a bismuth negative electrode potassium ion secondary battery obtained in example 1 of the present invention;

FIG. 3 is a diagram showing cycle performance of a bismuth negative electrode potassium ion secondary battery obtained in example 1 of the present invention;

FIG. 4 is a diagram showing the cycle characteristics of a bismuth negative electrode potassium ion secondary battery obtained in example 2 of the present invention;

FIG. 5 is a cyclic voltammetry curve of a p-benzoquinone negative electrode potassium ion secondary battery obtained in example 3 of the present invention;

FIG. 6 is a graph showing the charge and discharge curves of a p-benzoquinone negative electrode potassium ion secondary battery obtained in example 3 of the present invention;

FIG. 7 is a graph showing the cycle performance of a p-benzoquinone negative electrode potassium ion secondary battery obtained in example 3 of the present invention;

FIG. 8 is a graph showing the rate performance of a p-benzoquinone negative electrode potassium ion secondary battery obtained in example 3 of the present invention;

FIG. 9 is a graph showing the cycle performance of a p-benzoquinone negative electrode potassium ion secondary battery obtained in example 4 of the present invention.

FIG. 10 is a charge-discharge curve diagram of a Prussian-like white (K _1.68 Fe _1.09 Fe (CN) ₆.2.1H ₂ O) positive electrode potassium ion secondary battery obtained in example 5 of the present invention;

Fig. 11 is a graph showing cycle performance of the bismuth negative electrode potassium ion secondary battery obtained in comparative example 1 of the present invention in different electrolytes.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that various changes or modifications can be made by those skilled in the art after reading the disclosure of the present invention, and such equivalents also fall within the scope of the invention.

the experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.