Lithium primary battery electrolyte and preparation method thereof

Abstract

The present application belongs to the technical field of lithium primary battery, and particularly relates to a preparation method of lithium primary battery electrolyte, which comprises the following steps: dissolving lithium nitrate in acetone and fully stirring to make the lithium nitrate fully dissolved until the solution is clear and transparent; adjusting the lithium salt concentration in the solution to 1.5-2 mol / L; adding fluoroethylene carbonate and fully stirring until the solution is clear and transparent; in the solution, the volume ratio of fluoroethylene carbonate to acetone is 1:1-1:3; finally, adding propylene carbonate and fully stirring until the solution is clear and transparent; in the solution, the volume ratio of propylene carbonate to acetone is 1:2-1:4. The present application ensures that the electrolyte has high conductivity and can bear high efficient transportation of lithium ions, effectively increasing the discharge specific capacity and specific energy of the battery. In addition, the present application further provides a lithium primary battery electrolyte.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium primary battery, and particularly relates to a lithium primary battery electrolyte and a preparation method thereof. BACKGROUND

[0002] The lithium primary battery is a chemical power supply based on a conversion reaction and using metal lithium as a negative electrode of the battery, and has many advantages such as high discharge specific energy, good storage performance, and stable discharge voltage platform, and has great development prospects.

[0003] However, with the development of technology, the requirement for the specific energy of the lithium primary battery is higher and higher. Therefore, in order to further improve the specific energy of the lithium primary battery, it is necessary to convert the non-active components in the battery into active components. However, it is difficult to obtain an electrolyte with high conductivity in the prior art, and therefore, a new technical solution is urgently needed to solve the above problems. SUMMARY

[0004] One of the purposes of the present application is to provide a preparation method of a lithium primary battery electrolyte, which can ensure that the prepared electrolyte has high conductivity and can bear high-efficiency transportation of lithium ions, thereby effectively increasing the discharge specific capacity and specific energy of the battery.

[0005] In order to achieve the above purpose, the present application adopts the following technical solution:

[0006] A preparation method of a lithium primary battery electrolyte, comprising the following steps:

[0007] S1, dissolving lithium nitrate in acetone and fully stirring, so that the lithium nitrate is fully dissolved, until the solution is clear and transparent, and in the solution, the lithium salt concentration is adjusted to 1.5mol / L-2mol / L;

[0008] S2, adding fluoroethylene carbonate to the solution obtained in S1 and fully stirring, until the solution becomes clear and transparent, and in the solution, the volume ratio of fluoroethylene carbonate to acetone is 1:1-1:3;

[0009] S3, adding propylene carbonate to the solution obtained in S2 and fully stirring, until the solution becomes clear and transparent, and in the solution, the volume ratio of propylene carbonate to acetone is 1:2-1:4.

[0010] Preferably, S1 further comprises: using a magnetic stirrer to stir the mixture of lithium nitrate and acetone at a speed of 300r / min-500r / min for 0.5h-1h, until the lithium salt is completely dissolved, and the solution is clear and transparent, so as to improve the actual specific energy of the electrolyte.

[0011] Preferably, the S2 further comprises: stirring the solution by using a magnetic stirrer at a rotating speed of 400r / min-600r / min for 0.5h-1h until the solution is clear and transparent, so as to improve the actual specific energy of the electrolyte.

[0012] Preferably, the S3 further comprises: stirring the solution by using a magnetic stirrer at a rotating speed of 200r / min-400r / min for 1h-2h until the solution is clear and transparent, so as to improve the actual specific energy of the electrolyte.

[0013] Preferably, the S1, the S2 and the S3 are all operated in a glove box, in which the oxygen concentration and the water concentration are both less than 0.01ppm, so as to improve the actual specific energy of the electrolyte.

[0014] Preferably, in the S1, the lithium nitrate and the acetone are both ultra-dry grade, so as to improve the actual specific energy of the electrolyte.

[0015] Preferably, in the S2, the fluoroethylene carbonate is ultra-dry grade, so as to improve the actual specific energy of the electrolyte.

[0016] Preferably, in the S3, the propylene carbonate is ultra-dry grade, so as to improve the actual specific energy of the electrolyte.

[0017] Preferably, in the S1, a detection instrument is used to detect the concentration of the lithium salt.

[0018] The second object of the present application is to provide a lithium primary battery electrolyte prepared by the preparation method as above.

[0019] The present application has the following advantages: 1) the acetone and fluoroethylene carbonate are selected as the main components in the electrolyte, which can ensure the electrolyte to have high conductivity and can undertake the function of lithium ion transport, and the reaction between the fluoroethylene carbonate and the acetone can make the electrolyte have higher capacity, thereby significantly increasing the discharge specific capacity and specific energy of the battery, and the discharge voltage platform is less than 2.3V, which is lower than the discharge voltage platform of most lithium primary battery systems, so that the electrolyte can ensure relay discharge after the discharge of the positive electrode is completed, and the normal discharge of the positive electrode is not affected, and the introduction of propylene carbonate can make the electrolyte have a higher boiling point, thereby ensuring the wide temperature range application range of the electrolyte; 2) the preparation steps of the present application are clear, and the process can be standardized for production; 3) the present application selects lithium nitrate as the lithium salt and acetone as the main solvent, which can ensure the high dissociation degree of the lithium nitrate, thereby ensuring the high conductivity of the electrolyte system, and the acetone has high solvent solubility and lewis acid capacity, which is easy to have parasitic reaction with the metal lithium, and the lithium nitrate can effectively prevent the parasitic reaction of the acetone with the metal lithium, thereby improving the stability of the electrolyte system. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a preparation flowchart of the present application.

[0021] Figure 2 It is a photo of the electrolyte prepared in Example 1 of the present application under the conditions of 55℃ and-20℃.

[0022] Figure 3 It is the discharge curve of the electrolyte prepared in Example 1 of the present application and 1mol / L LiClO4PC / DME electrolyte respectively injected into a lithium carbon fluoride battery under the condition of 25℃.

[0023] Figure 4 It is the C1s spectrum of the XPS test of the pole piece after the discharge of the electrolyte prepared in Example 1 of the present application.

[0024] Figure 5 It is the XRD spectrum of the XPS test of the pole piece after the discharge of the electrolyte prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0025] As used in the specification and claims, certain terminology is used to refer to specific components that will be apparent to those skilled in the art, and a manufacturer can use different names to refer to the same component. Therefore, the description and claims in the specification do not use the difference in name as a way to distinguish the components, but use the difference in the function of the components as the criterion for distinguishing. As mentioned throughout the specification and claims, "comprising" is an open term, and should be construed to "comprising but not limited to". "Substantially" means within an acceptable error range, and those skilled in the art can solve technical problems within an acceptable error range and basically achieve technical effects.

[0026] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] In the present application, the inventor's inventive concept is as follows: the present application prepares an electrolyte with high electrical conductivity by selecting a suitable formula. The electrolyte in the battery is an important component in the battery, which accounts for a large part of the total weight of the battery. By endowing the electrolyte with electrochemical activity, it not only serves as a lithium ion transport function, but also participates in the discharge as an active material, thereby effectively improving the specific energy of the lithium primary battery.

[0028] At present, the inventor has found that the lithium primary batteries that have been engineered for application mainly include lithium manganese dioxide (Li / MnO2), lithium sulfuryl chloride (Li / SOCl2), lithium sulfur dioxide (Li / SO2) and lithium carbon fluoride (Li / CF x ) batteries, etc. Among them, the lithium carbon fluoride battery is the lithium primary battery system with the highest specific energy at present. Based on the solid-solid conversion reaction, the battery has a theoretical specific capacity of up to 864 mAh / g at x=1, and therefore can be widely used in the military and aerospace fields.

[0029] However, the inventor has found that it is difficult to obtain an electrolyte with high electrical conductivity in the prior art, so the present application prepares a new type of lithium primary battery electrolyte to solve the above problems.

[0030] A preparation method of a lithium primary battery electrolyte, comprising the following steps:

[0031] S1, dissolve lithium nitrate in acetone and stir thoroughly, so that the lithium nitrate is fully dissolved, until the solution is clear and transparent. In the solution, the lithium salt concentration is adjusted to 1.5 mol / L-2 mol / L;

[0032] S2, adding fluoroethylene carbonate to the solution obtained in S1 and stirring thoroughly until the solution becomes clear and transparent, the volume ratio of fluoroethylene carbonate to acetone in the solution being 1:1-1:3;

[0033] S3, adding propylene carbonate to the solution obtained in S2 and stirring thoroughly until the solution becomes clear and transparent, the volume ratio of propylene carbonate to acetone in the solution being 1:2-1:4.

[0034] Preferably, S1 further comprises: stirring the mixture of lithium nitrate and acetone at a speed of 300 r / min-500 r / min for 0.5 h-1 h by using a magnetic stirrer until the lithium salt is completely dissolved and the solution becomes clear and transparent, so as to improve the actual specific energy of the electrolyte.

[0035] Preferably, S2 further comprises: stirring the solution at a speed of 400 r / min-600 r / min for 0.5 h-1 h by using a magnetic stirrer until the solution becomes clear and transparent, so as to improve the actual specific energy of the electrolyte.

[0036] Preferably, S3 further comprises: stirring the solution at a speed of 200 r / min-400 r / min for 1 h-2 h by using a magnetic stirrer until the solution becomes clear and transparent, so as to improve the actual specific energy of the electrolyte.

[0037] Preferably, S1, S2 and S3 are all operated in a glove box, and in the glove box, the oxygen concentration and the water concentration are both less than 0.01 ppm, so as to improve the actual specific energy of the electrolyte.

[0038] Preferably, in S1, the lithium nitrate and the acetone are both super dry, so as to improve the actual specific energy of the electrolyte.

[0039] Preferably, in S2, the fluoroethylene carbonate is super dry, so as to improve the actual specific energy of the electrolyte.

[0040] Preferably, in S3, the propylene carbonate is super dry, so as to improve the actual specific energy of the electrolyte.

[0041] Preferably, in S1, the concentration of the lithium salt is detected by using a detection instrument, and the detection step can be performed outside the glove box.

[0042] A lithium primary battery electrolyte is prepared by the above method, and the electrolyte is applied to a lithium primary battery to improve the actual specific energy thereof.

[0043] The above and other aspects will be more apparent from the following Figures 1 to 5The application will be further described in connection with the specific examples, but not as a limitation to the application.

[0044] Example 1

[0045] Step 1, dissolve lithium nitrate (LiNO3) in acetone (PA) and stir with a magnetic stirrer at 300 r / min for 1 h until the solution is clear and transparent, with a lithium salt concentration of 1.5 mol / L.

[0046] Step 2, add fluoroethylene carbonate (FEC) to the solution obtained in Step 1 and stir with a magnetic stirrer at 400 r / min for 1 h until the solution is clear and transparent, with a volume ratio of FEC to PA of 1:1.

[0047] Step 3, add propylene carbonate (PC) to the solution obtained in Step 2 and stir with a magnetic stirrer at 200 r / min for 2 h until the solution is clear and transparent without stratification, with a volume ratio of PC to PA of 1:2.

[0048] Specifically, the reaction process of fluoroethylene carbonate (FEC) and N-methyl pyrrolidone (NMP) is as follows: under the action of an electric field, fluoroethylene carbonate (FEC) is decomposed into vinylene carbonate (VC) and hydrofluoric acid (HF), and vinylene carbonate (VC) is then combined with Li + ROCOOLi, Li2CO3 and Li2C2O4 are generated, and hydrofluoric acid (HF) is combined with Li + and acetone (PA) to form propyl alcohol and LiF.

[0049] Experimental results:

[0050] The relay electrolyte prepared in Example 1 has a wide application temperature range and is in a liquid state at 55°C and -20°C, as shown in Figure 2 As can be seen from the photos of the relay electrolyte at 55°C and -20°C, the electrolyte is in a liquid state at 55°C and -20°C.

[0051] In addition, as shown in Figure 3 , the relay electrolyte prepared in Example 1 has excellent electrochemical performance in a lithium- fluorocarbon battery and has a higher specific capacity than the traditional 1 mol / L LiClO4 PC / DME electrolyte when discharged at a rate of 0.01C.

[0052] As shown in Figure 3The relay electrolyte prepared in Example 1 has higher specific capacity than the conventional electrolyte in the lithium-carbon fluoride battery, which is mainly because the FEC and PA in the relay electrolyte have reacted to provide additional capacity for the battery, and the high lithium salt dissociation degree and low electrolyte viscosity ensure high conductivity of the electrolyte, thus ensuring that the positive electrode capacity can be fully utilized before the relay discharge.

[0053] Referring to Figure 4 and Figure 5 The C1s spectrum and XRD spectrum of the positive electrode sheet after the discharge of the lithium-carbon fluoride battery of the relay electrolyte prepared in Example 1 show the formation of ROCOOLi, Li2CO3, Li2C2O4 and LiF, indicating the smooth progress of the discharge of the carbon fluoride material and the relay reaction.

[0054] As can be seen from the above spectrum, the formation of ROCOOLi, Li2CO3 and Li2C2O4 indicates that the FEC has reacted; and the XRD spectrum shows the formation of LiF, which further indicates the normal discharge of the carbon fluoride material, and also indicates the smooth progress of the reaction of HF and PA.

[0055] Example 2

[0056] Step 1, dissolve lithium nitrate (LiNO3) in acetone (PA), and fully stir with a magnetic stirrer at a speed of 500 r / min for 0.5 h to fully dissolve until the solution is clear and transparent, and the lithium salt concentration is 2 mol / L.

[0057] Step 2, add fluoroethylene carbonate (FEC) to the solution obtained in Step 1, and fully stir with a magnetic stirrer at a speed of 600 r / min for 0.5 h to fully dissolve until the solution is clear and transparent, and the volume ratio of FEC to PA is 1:3.

[0058] Step 3, add propylene carbonate (PC) to the solution obtained in Step 2, and fully stir with a magnetic stirrer at a speed of 400 r / min for 1 h until the solution is clear and transparent without stratification, and the volume ratio of PC to PA is 1:4.

[0059] It can be detected that the electrolyte of Example 2 also has high conductivity.

[0060] Example 3

[0061] Step 1, dissolve lithium nitrate (LiNO3) in acetone (PA), and fully stir with a magnetic stirrer at a speed of 400 r / min for 0.7 h to fully dissolve until the solution is clear and transparent, and the lithium salt concentration is 2 mol / L.

[0062] Step 2, add FEC to the solution obtained in step 1, and stir the solution with a magnetic stirrer at a speed of 500 r / min for 1 h until the solution is clear and transparent, and the volume ratio of FEC to PA is 1:2.

[0063] Step 3, add PC to the solution obtained in step 2, and stir the solution with a magnetic stirrer at a speed of 400 r / min for 1 h until the solution is clear and transparent, and the volume ratio of PC to PA is 1:2.

[0064] It is found that the electrolyte obtained in example 3 also has high conductivity.

[0065] Obviously, in the present application, PA and FEC are selected as the main components of the electrolyte, which can not only ensure the electrolyte to have high conductivity and bear the function of transporting lithium ions, but also can make the electrolyte have higher capacity by the reaction between FEC and PA, thereby significantly increasing the specific discharge capacity and specific energy of the battery, and the discharge voltage platform is less than 2.3 V, which is lower than the discharge voltage platform of most lithium primary battery systems, so that the electrolyte can ensure relay discharge after the discharge of the positive electrode is completed, and does not affect the normal discharge of the positive electrode. The introduction of PC makes the electrolyte have a higher boiling point, thereby ensuring the wide temperature range of the application of the electrolyte. In addition, the solvent in the present application can directly react, thereby avoiding the addition of additives.

[0066] According to the disclosure and teaching of the above description, those skilled in the art of the present application can also make changes and modifications to the above embodiments. Therefore, the present application is not limited to the above specific embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art on the basis of the present application all belong to the protection scope of the present application. In addition, although some specific terms are used in the present specification, these terms are only used for convenience of description, and do not constitute any limitation on the present application.

Claims

1. A method for preparing an electrolyte for a lithium primary battery, characterized by, The method comprises the following steps: S1, dissolving lithium nitrate in acetone and stirring thoroughly, so that the lithium nitrate is dissolved thoroughly, until the solution is clear and transparent, in the solution, the lithium salt concentration is adjusted to 1.5-2 mol / L; S2, adding fluoroethylene carbonate to the solution obtained in S1 and stirring thoroughly until the solution becomes clear and transparent, in the solution, the volume ratio of fluoroethylene carbonate to acetone is 1:1-1:3, the specific reaction process of fluoroethylene carbonate and N-methyl pyrrolidone is that fluoroethylene carbonate is decomposed into vinylene carbonate and hydrofluoric acid under the action of an electric field, and the vinylene carbonate is then reacted with Li + ROCOOLi, Li2CO3 and Li2C2O4 are generated, hydrofluoric acid and Li + and acetone to form propanol and LiF; S3, adding propylene carbonate to the solution obtained in S2 and stirring thoroughly, until the solution is clear and transparent, in the solution, the volume ratio of propylene carbonate to acetone is 1:2-1:4, S1, S2 and S3 are all operated in a glove box, in the glove box, the oxygen concentration and water concentration are both less than 0.01 ppm, the prepared electrolyte is liquid at-20℃ and 55℃, which ensures relay discharge after the positive electrode discharge is completed.

2. The method for preparing the lithium primary battery electrolyte as described in claim 1, characterized in that, In S1, the mixed solution of lithium nitrate and acetone is stirred by a magnetic stirrer at a speed of 300-500 r / min for 0.5-1 h, until the lithium salt is dissolved completely and the solution is clear and transparent.

3. The method for preparing the lithium primary battery electrolyte as described in claim 1, characterized in that, In S2, the solution is stirred by a magnetic stirrer at a speed of 400-600 r / min for 0.5-1 h, until the solution is clear and transparent.

4. The method for preparing the lithium primary battery electrolyte as described in claim 1, characterized in that, In S3, the solution is stirred by a magnetic stirrer at a speed of 200-400 r / min for 1-2 h, until the solution is clear and transparent.

5. The method of claim 2, wherein the lithium primary battery electrolyte is prepared by the steps of: a) dissolving the lithium salt in the solvent; b) adding the lithium salt solution to the electrolyte solution; and c) adding the electrolyte solution to the electrolyte solution. The lithium nitrate and the acetone are both ultra-dry grade.

6. The method of claim 3, wherein the lithium primary battery electrolyte is prepared by the steps of: a) dissolving the lithium salt in the solvent; b) adding the additive to the solution of step a); and c) adding the lithium salt to the solution of step b). The fluoroethylene carbonate is ultra-dry grade.

7. The method of claim 4, wherein the lithium primary battery electrolyte is prepared by the steps of: a) dissolving the lithium salt in the solvent; b) adding the lithium salt solution to the electrolyte solution; and c) stirring the mixture until the lithium salt is dissolved. The propylene carbonate is ultra-dry grade.

8. A lithium primary battery electrolyte, characterized by: The electrolyte is prepared by the method according to any one of claims 1-7.

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