CN111244492A - A high specific energy primary lithium-sulfur battery and its application - Google Patents

Abstract

The invention relates to a high-specific-energy primary lithium-sulfur battery and application thereof, wherein the battery comprises a negative electrode, a positive electrode, a diaphragm and electrolyte, the positive electrode is made of a sulfur-carbon composite positive electrode material, the sulfur-carbon composite positive electrode material comprises a sulfur simple substance, conductive carbon black and a binder, the electrolyte comprises lithium salt, a solvent and a diluent, the solvent is acetonitrile, and the addition ratio of the electrolyte to the sulfur simple substance is (0.2-3) mL:1 g. Compared with the prior art, the lithium-sulfur battery provided by the invention has the advantages that the dissolution of polysulfide is greatly inhibited, the addition of electrolyte in the lithium-sulfur battery is reduced, the utilization rate of positive active substances in the lithium-sulfur battery is improved, and the lithium-sulfur battery has extremely high energy density compared with the traditional lithium-ion battery.

Description

A high specific energy primary lithium-sulfur battery and its application

technical field

The invention relates to the technical field of lithium metal batteries, in particular to a high specific energy primary lithium-sulfur battery and its application.

Background technique

Lithium-ion batteries are inseparable from human society and are widely used in all aspects of human production and life. They are widely used in energy storage grids, mobile communications, electric vehicles, aerospace and other fields. Traditional lithium-ion batteries use lithium metal oxides (such as lithium cobalt oxide LiCoO ₂ , ternary material LiNi _x Co _y Mn _1-xy O ₂ ) or lithium iron phosphate (LiFePO ₄ ) as the positive electrode, graphite as the negative electrode, and the electrode material The low theoretical specific capacity and relatively low theoretical energy density limit the wide application of Li-ion batteries in emerging applications requiring high specific energy and high energy density. Lithium-sulfur batteries use sulfur as the positive electrode and lithium metal as the negative electrode. Since sulfur and lithium metal have theoretical specific capacities of 1672mAh g ^-1 and 3860mAh g ^-1 , respectively, and have a theoretical energy density close to 2600Wh kg ^-1 , it has attracted widespread attention. It is considered to be a new generation of energy storage system with great application prospects.

However, there are still many problems in lithium-sulfur batteries, which limit the practical application of lithium-sulfur batteries. First, the cathode sulfur in lithium-sulfur batteries is non-conductive, and a large amount of conductive carbon needs to be added, resulting in a low content of cathode active materials. Secondly, the electrolyte in the lithium-sulfur battery is usually an ether electrolyte. In this type of electrolyte, the discharge process of the lithium-sulfur battery is divided into two stages. In the first stage, the sulfur is converted into soluble polysulfide, which dissolves In the electrolyte, a more serious "shuttle effect" is caused, and such batteries require a large amount of electrolyte to meet the dissolution of polysulfides. Excessive addition of electrolyte severely limits the actual energy density of lithium-sulfur batteries, making the The actual energy density of lithium-sulfur batteries is much lower than that of traditional lithium-ion batteries, making it difficult to commercialize lithium-sulfur batteries.

Patent CN104143614A discloses a new lithium-sulfur battery system, including electrolyte and matching separator. The electrolyte is a lithium salt solution with a concentration of 0.1-3mol/L, and the lithium salt solute in the lithium salt solution is one or more mixtures of lithium fluoride, lithium chloride, lithium bromide or lithium iodide; the solvent is One or more mixtures of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetramethyl sulfone, tetrahydrofuran, N-methylpyrrolidone, and acetonitrile The diaphragm is a microporous membrane with a pore size of 0.5-10 nanometers or a dense membrane containing anions. In this patent, using a lithium salt solution with a lower concentration as the electrolyte will cause the electrolyte to react with the negative electrode lithium metal, corrode and consume the negative electrode metal, and a large amount of electrolyte is required to ensure the normal dissolution of polysulfur, which limits the lithium-sulfur battery. actual energy density.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high specific energy primary lithium-sulfur battery and its application in order to solve the above problems, and overcome the defects of low positive electrode sulfur content and high electrolyte addition in the lithium-sulfur battery.

The object of the present invention is achieved through the following technical solutions:

A high specific energy primary lithium-sulfur battery, the battery comprises a negative electrode, a positive electrode, a separator and an electrolyte, the positive electrode is made of a sulfur-carbon composite positive electrode material, and the sulfur-carbon composite positive electrode material comprises sulfur element, conductive carbon black and A binder, the electrolyte solution comprises lithium salt, a solvent and a diluent, the solvent is acetonitrile, and the addition ratio (E/S) of the electrolyte solution to the elemental sulfur is (0.2-3) mL:1 g. The energy density of the obtained lithium-sulfur battery is 500-1200Wh kg ^-1 , wherein the negative electrode is a lithium metal material, the positive electrode is a flexible self-supporting pole piece composed of a sulfur-carbon composite material and a binder, and the separator is a commercial separator, which is Celgard Company. 2500 type diaphragm produced.

Preferably, the conductive carbon black is selected from one or more of Ketjen black, acetylene black or Super P.

Preferably, in the sulfur-carbon composite positive electrode material, the mass ratio of the sulfur element, the conductive carbon black and the polytetrafluoroethylene is (30-95):(3-40):(2-10). Further preferably, the mass ratio of the sulfur element, conductive carbon black and polytetrafluoroethylene is 50:10:9.

Preferably, the sulfur-carbon composite cathode material is prepared by the following preparation method:

(a) Mixing elemental sulfur and conductive carbon black uniformly, then sealing and sintering in an inert atmosphere to obtain a cathode material precursor, wherein the inert atmosphere is an argon atmosphere;

(b) adding the positive electrode material precursor and the binder obtained in the step (a) into ethanol, stirring uniformly to a mass, to obtain a crude positive electrode material product, wherein the binder is a polytetrafluoroethylene dispersion;

(c) using a roller press to repeatedly roll the positive electrode material crude product obtained in the step (b), and continuously reduce the rolling interval, and then dry to obtain the sulfur-carbon composite positive electrode material.

Preferably, in step (a), the sintering temperature is 140-170° C., and the sintering time is 10-14 h.

Preferably, in step (c), the drying process is specifically as follows: firstly, the rolled cathode material crude product is hung to dry, and then dried in an oven at a temperature of 60-80° C. for 8-18 hours.

Preferably, the lithium salt is lithium bistrifluoromethanesulfonimide (represented by LiTFSI), and the diluent is hydrofluoroether.

Preferably, the hydrofluoroether is selected from 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (CAS: 16627-68-2), 1,1, 2,2-Tetrafluoroethyl-2,2,2-trifluoroethyl ether (CAS:406-78-0), 1,1,2,2-tetrafluoroethylethyl ether (CAS:512- 51-6) one or more.

Preferably, in the electrolyte, the molar ratio of the acetonitrile to the lithium salt is (1-9):1, and the volume ratio of the acetonitrile to the diluent is (4-9):(1-6).

Preferably, the electrolyte is obtained by the following preparation method: firstly, acetonitrile and lithium bistrifluoromethanesulfonimide are configured into a uniform solution according to a molar ratio, then hydrofluoroether is added, and after mixing uniformly, it is left to stand to obtain primary lithium Electrolyte for sulfur batteries.

Application of a high specific energy primary lithium-sulfur battery. The battery can be made into cylindrical battery, single-layer soft pack battery and 2032 type button battery.

By preparing a sulfur-carbon positive electrode with high sulfur loading and an acetonitrile system electrolyte, the invention reduces the addition amount of the electrolyte, realizes the preparation of a primary lithium-sulfur battery with high specific energy, and the prepared positive electrode sheet has good ductility and conductivity. and high active material loading, the prepared electrolyte has high ionic conductivity, good rate performance at high temperature (60°C) and low temperature (-40°C), and the prepared primary lithium-sulfur battery has extremely high high energy density (400-1200Whkg ^-1 ), excellent high temperature and low temperature performance, and excellent discharge capacity at high current density.

Compared with the prior art, the beneficial effects of the present invention are as follows: the primary lithium-sulfur battery of the present invention uses a new type of electrolyte, which greatly inhibits the dissolution of polysulfides and reduces the addition of electrolyte in the lithium-sulfur battery. , which improves the utilization rate of the positive active material in the lithium-sulfur battery, and has a very high energy density compared with the traditional lithium-ion battery.

Description of drawings

Fig. 1 is the discharge curve comparison diagram of embodiment 1, 2 and comparative example 1, 2;

Fig. 2 is the discharge curve comparison diagram of embodiment 3 and comparative example 3;

FIG. 3 is a comparison diagram of the discharge curves of Examples 4, 5 and Comparative Example 4. FIG.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 500g of sulfur powder, mix 100g of Ketjen black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material The precursor and 90 g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent, and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press , to obtain a ductile positive electrode sheet with a thickness of 0.9 mm, which was then dried in an oven at a temperature of 60 °C for 12 h, and then cut into a polar sheet with a size of 285 × 37.5 × 0.9 mm.

Dissolve acetonitrile solvent and LiTFSI in a molar ratio of 2:1, take 20 mL of acetonitrile solvent, add 55 g of LiTFSI, stir until completely dissolved (the volume will expand to about 40 mL after complete dissolution, the same below), take 30 mL of the dissolved mixed solution, and 30 mL of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether was added to the mixed solution to obtain an electrolyte with an ionic conductivity of 2× at 60°C 10 ^-3 S cm ^-1 , the ionic conductivity at 40°C is 1.3×10 ^-3 S cm ^-1 , and the ionic conductivity at -40°C is 0.2×10 ^-3 S cm ^-1 .

The positive pole piece, the separator and the lithium tape were wound into a 26500 cylindrical battery, and the electrolyte was added according to the ratio of E/S=1mL:1g to obtain a primary lithium-sulfur battery. The energy density of the primary lithium-sulfur battery was 610Wh kg ^-1 , the lithium-sulfur battery is discharged at a rate of C/1000. It can be seen from Figure 1 that the battery has higher discharge capacity and higher energy density than the lithium-sulfur battery using ether electrolyte under the same discharge conditions.

Example 2

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 500g of sulfur powder, mix 100g of Ketjen black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material The precursor and 90 g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press, A ductile positive electrode sheet with a thickness of 0.9 mm was obtained, then dried in an oven at a temperature of 60° C. for 12 hours, and then cut into a polar sheet with a size of 285×37.5×0.9 mm.

Dissolve acetonitrile solvent and LiTFSI in a molar ratio of 2:1, take 20 mL of acetonitrile solvent, add 55 g of LiTFSI, stir until completely dissolved, take 30 mL of the dissolved mixed solution, and add 30 mL of 1, 1, 2, 2 to the mixed solution - Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether to obtain an electrolyte solution having an ionic conductivity of 2×10 ^-3 Scm ^-1 at 60°C and an ionic conductivity of 40°C The ionic conductivity is 0.2× ^{10 -3 S} cm ^-1 at -40° ^C .

The positive pole piece, the separator and the lithium tape were wound into a 26500 cylindrical battery, and the electrolyte was added according to the ratio of E/S=1mL:1g to obtain a primary lithium-sulfur battery. The energy density of the primary lithium-sulfur battery was 610Wh kg ^-1 , the lithium-sulfur battery is discharged at a rate of C/500. It can be seen from Figure 1 that the battery has higher discharge capacity and higher energy density than the lithium-sulfur battery using ether electrolyte under the same discharge conditions.

Example 3

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 500g of sulfur powder, mix 100g of Ketjen black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material The precursor and 90 g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press, A ductile positive electrode sheet with a thickness of 0.9 mm was obtained, then dried in an oven at a temperature of 60° C. for 12 hours, and then cut into a polar sheet with a size of 30×40×0.9 mm.

Dissolve acetonitrile solvent and LiTFSI in a molar ratio of 2:1, take 20 mL of acetonitrile solvent, add 55 g of LiTFSI, stir until completely dissolved, take 30 mL of the dissolved mixed solution, and add 30 mL of 1, 1, 2, 2 to the mixed solution -Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether to obtain an electrolyte solution having an ionic conductivity of 2×10 ^-3 Scm ^-1 at 60°C and an ionic conductivity of 40°C The ionic conductivity is 0.2× ^{10 -3 S} cm ^-1 at -40° ^C .

The positive pole piece, the separator and the lithium strip are assembled into a single-layer soft pack battery, and the electrolyte is added according to the ratio of E/S=1.6mL:1g to obtain a primary lithium-sulfur battery. The energy density of the primary lithium-sulfur battery is 600Wh kg ^{- 1.} Discharge the lithium-sulfur battery at a rate of C/1000. It can be seen from Figure 2 that under the same electrolyte addition conditions and discharge conditions, the battery using acetonitrile electrolyte has higher discharge capacity and higher discharge capacity. Energy Density.

Example 4

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 50g of sulfur powder, mix 10g of Ketjen black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material The precursor and 9 g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a crude positive electrode material product; A ductile positive electrode sheet was obtained, the thickness of which was 0.9 mm, and then dried in an oven at a temperature of 60° C. for 12 hours, and then cut into a polar sheet with a size of φ12 mm.

Dissolve acetonitrile solvent and LiTFSI according to the molar ratio of 2:1, take 2 mL of acetonitrile solvent, add 5.5 g of LiTFSI, stir until completely dissolved, take 3 mL of the dissolved mixed solution, and add 3 mL of 1,1,2, 2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether to obtain an electrolyte solution having an ionic conductivity of 2×10 -3 Scm -1 at 60°C and an ionic conductivity of 2×10 ^-3 Scm ^-1 at 40°C The electrical conductivity is 1.3×10 ^-3 S cm ^-1 , and the ionic conductivity at -40°C is 0.2×10 ^-3 S cm ^-1 .

Assemble the positive pole piece, separator and lithium strip to form a 2032 type button battery, and add electrolyte according to the ratio of E/S=1mL:1g to obtain a primary lithium-sulfur battery. The theoretical energy density of the primary lithium-sulfur battery is 685Wh kg ^{- 1} (ignoring the quality of the battery shell), discharge the lithium-sulfur battery at a rate of C/1000. It can be seen from Figure 3 that compared with the lithium-sulfur battery using ether electrolyte, the lithium-sulfur battery is at E/S=1mL:1g. Under the condition, it has a higher discharge specific capacity.

Example 5

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 50g of sulfur powder, mix 10g of Ketjen black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material The precursor and 9 g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a crude positive electrode material product; A ductile positive electrode sheet was obtained, the thickness of which was 0.9 mm, and then dried in an oven at a temperature of 60° C. for 12 hours, and then cut into a polar sheet with a size of φ12 mm.

Dissolve acetonitrile solvent and LiTFSI according to the molar ratio of 2:1, take 2 mL of acetonitrile solvent, add 5.5 g of LiTFSI, stir until completely dissolved, take 3 mL of the dissolved mixed solution, and add 3 mL of 1,1,2, 2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether to obtain an electrolyte solution having an ionic conductivity of 2×10 -3 Scm -1 at 60°C and an ionic conductivity of 2×10 ^-3 Scm ^-1 at 40°C The electrical conductivity is 1.3×10 ^-3 S cm ^-1 , and the ionic conductivity at -40°C is 0.2×10 ^-3 S cm ^-1 .

A 2032 type button battery was assembled by assembling the positive pole piece, the separator and the lithium belt, and adding the electrolyte according to the ratio of E/S=2mL:1g to obtain a primary lithium-sulfur battery. The theoretical energy density of the primary lithium-sulfur battery is 580Wh kg ^{- 1} (ignoring the quality of the battery shell), discharge the lithium-sulfur battery at a rate of C/500. It can be seen from Figure 3 that compared with the lithium-sulfur battery using ether electrolyte, the lithium-sulfur battery is at E/S=2mL:1g. Under the condition, it has a higher discharge specific capacity.

Example 6

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 50g of sulfur powder, mix 10g of superP evenly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor. and 9g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press to obtain a The expanded positive electrode sheet, with a thickness of 0.9 mm, was dried in an oven at a temperature of 80° C. for 10 hours, and then cut into a polar sheet with a size of φ12 mm.

Dissolve acetonitrile solvent and LiTFSI according to the molar ratio of 2:1, take 2 mL of acetonitrile solvent, add 5.5 g of LiTFSI, stir until completely dissolved, take 3 mL of the dissolved mixed solution, and add 3 mL of 1,1,2, 2-tetrafluoroethyl-2,2,2-trifluoroethyl ether to obtain an electrolyte solution having an ionic conductivity of 2×10 ^-3 Scm ^-1 at 60°C and an ionic conductivity of 40°C is 1.3×10 ^-3 S cm ^-1 , and the ionic conductivity at -40°C is 0.2×10 ^-3 S cm ^-1 .

A 2032 type button battery was assembled by assembling the positive pole piece, the separator and the lithium strip, and adding the electrolyte according to the ratio of E/S=1mL:1g to obtain a primary lithium-sulfur battery. The theoretical energy density of the primary lithium-sulfur battery is 660Wh kg ^{- 1} (ignoring battery case mass).

Example 7

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 30g of sulfur powder, mix 20g of Ketjen black evenly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor. The precursor and 9 g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a crude positive electrode material product; A ductile positive electrode sheet was obtained, the thickness of which was 0.9 mm, and then dried in an oven at a temperature of 80° C. for 8 hours, and then cut into a polar sheet with a size of φ12 mm.

Dissolve acetonitrile solvent and LiTFSI according to the molar ratio of 2:1, take 2 mL of acetonitrile solvent, add 5.5 g of LiTFSI, stir until completely dissolved, take 3 mL of the dissolved mixed solution, and add 3 mL of 1,1,2, 2-Tetrafluoroethyl ethyl ether gave an electrolyte with ionic conductivity of 2×10 ^-3 S cm ^-1 at 60°C ^and 1.3×10 ^-3 S cm -1 at 40°C ¹ , the ionic conductivity at -40°C is 0.2×10 ^-3 S cm ^-1 .

Assemble the positive pole piece, separator and lithium strip to form a 2032 type button battery, add electrolyte according to the ratio of E/S=2mL:1g, and obtain a primary lithium-sulfur battery. The energy density of the primary lithium-sulfur battery is 400Wh kg ^-1 .

Example 8

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 950 g of sulfur powder, mix 400 g of acetylene black evenly, and sinter at 170° C. for 10 hours in an argon airtight environment to obtain a positive electrode material precursor. The solid and 10g polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent, and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press, A ductile positive electrode sheet was obtained with a thickness of 0.9 mm, which was then dried in an oven at a temperature of 60° C. for 18 hours, and then cut into a polar sheet with a size of 285×37.5×0.9 mm.

Dissolve acetonitrile solvent and LiTFSI according to the molar ratio of 9:1, take 20 mL of acetonitrile solvent, add 55 g of LiTFSI, stir until completely dissolved, take all the dissolved mixed solution, and add 5 mL of 1,1,2,2- Tetrafluoroethyl-2,2,2-trifluoroethyl ether to obtain an electrolytic solution.

The positive pole piece, the separator and the lithium tape are wound to form a 26500 cylindrical battery, and the electrolyte is added according to the ratio of E/S=0.2mL:1g to obtain a primary lithium-sulfur battery. The energy density of the primary lithium-sulfur battery is 720Wh kg ^{- 1} .

Example 9

A high specific energy primary lithium-sulfur battery is prepared by the following preparation method: weigh 500g of sulfur powder, mix 3g of SuperP evenly, and sinter at 140°C for 14h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material precursor and 2g of polytetrafluoroethylene dispersion (solid content of 60%) was added to the ethanol solvent, and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press to obtain a The extended positive electrode sheet, with a thickness of 0.9 mm, was dried in an oven at a temperature of 80° C. for 8 hours, and then cut into a polar sheet with a size of 285×37.5×0.9 mm.

Dissolve acetonitrile solvent and LiTFSI according to the molar ratio of 7:1, take 20 mL of acetonitrile solvent, add 55 g of LiTFSI, stir until completely dissolved, take all the dissolved mixed solution, and add 13.3 mL of 1,1,2, 2-tetrafluoroethyl ethyl ether, the positive pole piece, the separator and the lithium tape are wound into a 26500 cylindrical battery, and the electrolyte is added according to the ratio of E/S=3mL:1g to obtain a primary lithium-sulfur battery. The energy density of the sulfur battery is 400Wh kg ^-1 .

It can be seen from Example 1-9 and Figure 1-3 that when the addition ratio (E/S) of the electrolyte to the elemental sulfur is (0.2-3) mL:1g, and the electrolyte contains acetonitrile, the obtained primary lithium The electrical properties of sulfur batteries are very good.

Comparative Example 1

A common primary lithium-sulfur battery is prepared by the following preparation method: Weigh 500g of sulfur powder, mix 100g of Ketjen Black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material precursor body and 90g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press to obtain The extensible positive electrode piece, the thickness of which is 0.9mm, is cut into a pole piece with a size of 285×37.5×0.9mm.

A 26500 cylindrical battery was formed by winding the positive electrode, separator and lithium tape, and adding ether electrolyte in the ratio of E/S=1mL:1g, the ionic conductivity of the ether electrolyte at 60°C was 1.8×10 ^{− 3} S cm ^-1 , the ionic conductivity at 40°C is 1.4×10 ^-3 S cm ^-1 , and a primary lithium-sulfur battery with an energy density of 120Wh kg ^-1 is obtained. The lithium-sulfur battery is discharged at a rate of C/1000. It can be seen from Figure 1 that the discharge capacity of the lithium-sulfur battery using ether electrolyte is far less than that of acetonitrile electrolysis when the amount of electrolyte added is E/S=1mL g ^-1 The ether electrolyte is the lithium-sulfur battery electrolyte LS-009 provided by Duoduo Reagent Network, and the electrolyte contains LiTFSI, 1,3-dioxolane (DOL), 1,2-dimethoxy Ethane (DME) and LiNO ₃ , wherein the concentration of LiTFSI is 1.0M, the volume ratio of DOL and DME is 1:1, and the volume content of LiNO ₃ is 2.0%.

Comparative Example 2

A common primary lithium-sulfur battery is prepared by the following preparation method: Weigh 500g of sulfur powder, mix 100g of Ketjen Black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material precursor body and 90g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press to obtain The extensible positive electrode piece, the thickness of which is 0.9mm, is cut into a pole piece with a size of 285×37.5×0.9mm.

The positive pole piece, separator and lithium tape were wound to form a 26500 cylindrical battery, and ether electrolyte was added according to the ratio of E/S=1mL:1g. The ionic conductivity of the ether electrolyte at 60 °C and the -40 °C The ionic conductivity was the same as that of the ether electrolyte of Comparative Example 1, and a primary lithium-sulfur battery was obtained, and the energy density of the primary lithium-sulfur battery was 120Wh kg ^-1 . The lithium-sulfur battery was discharged at a rate of C/500. It can be seen from Figure 1 that the discharge capacity of the lithium-sulfur battery using ether electrolyte is far less than that of acetonitrile electrolyte when the electrolyte addition amount is E/S=1mL:1g. The provided lithium-sulfur battery electrolyte LS-009.

Comparative Example 3

A common primary lithium-sulfur battery is prepared by the following preparation method: Weigh 500g of sulfur powder, mix 100g of Ketjen Black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material precursor body and 90g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press to obtain The extensible positive electrode piece, the thickness of which is 0.9mm, is cut into a pole piece with a size of 30×40×0.9mm.

Assemble the positive pole piece, separator and lithium strip into a single-layer soft pack battery, add ether electrolyte in the ratio of E/S=1.6mL:1g, the ionic conductivity of the ether electrolyte at 60 ℃ and -40 ℃ The ionic conductivities of the batteries are the same as those of the ether electrolyte of Comparative Example 1, and a primary lithium-sulfur battery is obtained, and the energy density of the primary lithium-sulfur battery is 70Wh kg ^-1 . The lithium-sulfur battery is discharged at a rate of C/1000. It can be seen from Figure 2 that the discharge capacity of the lithium-sulfur battery using ether electrolyte is far less than that of acetonitrile when the amount of electrolyte added is E/S=1.6mL g ^-1 Electrolyte, the ether electrolyte is lithium-sulfur battery electrolyte LS-009 provided by Duoduo Reagent Network.

Comparative Example 4

An ordinary primary lithium-sulfur battery is prepared by the following preparation method: Weigh 50g of sulfur powder, mix 10g of Ketjen Black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor. The solid and 9g of polytetrafluoroethylene dispersion (solid content of 60%) were added to the ethanol solvent and mixed uniformly to obtain a powdery positive electrode material crude product; the prepared positive electrode material crude product was repeatedly rolled on a roller press to obtain The extensible positive electrode piece has a thickness of 0.9mm and is cut into a pole piece with a size of φ12mm.

Assemble the positive pole piece, separator and lithium belt into a 2032 type button battery, add ether electrolyte according to the ratio of E/S=1mL:1g, the ionic conductivity of the ether electrolyte at 60 ℃ and -40 ℃. The ionic conductivity was the same as that of the ether electrolyte in Comparative Example 1, and a primary lithium-sulfur battery was obtained. The theoretical energy density of the primary lithium-sulfur battery was 200Wh kg ^-1 (ignoring the mass of the battery case). The lithium-sulfur battery was discharged at a rate of C/1000. It can be seen from Figure 3 that the discharge capacity of the lithium-sulfur battery using ether electrolyte is far less than that of acetonitrile electrolyte. Battery electrolyte LS-009.

Comparative Example 5

A common primary lithium-sulfur battery is prepared by the following preparation method: Weigh 500g of sulfur powder, mix 100g of Ketjen Black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material precursor The solid and 90g polytetrafluoroethylene dispersion liquid (solid content of 60%) were added to the ethanol solvent, and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press, An extensible positive electrode sheet was obtained, the thickness of which was 0.9 mm, and was cut to a size of 285×37.5×0.9 mm.

Dissolve acetonitrile solvent and LiTFSI in a molar ratio of 2:1, take 20 mL of acetonitrile solvent, add 55 g of LiTFSI, stir until completely dissolved, take 30 mL of the dissolved mixed solution, and add 30 mL of 1, 1, 2, 2 to the mixed solution - Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether to obtain an electrolyte solution having an ionic conductivity of 2×10 -3 Scm -1 at 60°C and an ionic conductivity of 2×10 ^-3 Scm ^-1 at -40°C The conductivity was 0.2×10 ^-3 S cm ^-1 .

The positive pole piece, the separator and the lithium tape are wound into a 26500 cylindrical battery, and the electrolyte is added according to the ratio of E/S=0.1mL:1g to obtain a primary lithium-sulfur battery. The energy density of the primary lithium-sulfur battery is 240Wh kg ^{- 1} .

Comparative Example 6

A common primary lithium-sulfur battery is prepared by the following preparation method: Weigh 500g of sulfur powder, mix 100g of Ketjen Black uniformly, and sinter at 155°C for 12h in an argon airtight environment to obtain a positive electrode material precursor, and the positive electrode material precursor The solid and 90g polytetrafluoroethylene dispersion liquid (solid content of 60%) were added to the ethanol solvent, and mixed uniformly to obtain a powdery cathode material crude product; the prepared cathode material crude product was repeatedly rolled on a roller press, An extensible positive electrode sheet was obtained, the thickness of which was 0.9 mm, and was cut to a size of 285×37.5×0.9 mm.

Dissolve acetonitrile solvent and LiTFSI in a molar ratio of 2:1, take 20 mL of acetonitrile solvent, add 55 g of LiTFSI, stir until completely dissolved, take 30 mL of the dissolved mixed solution, and add 30 mL of 1, 1, 2, 2 to the mixed solution - Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether to obtain an electrolyte solution having an ionic conductivity of 2×10 -3 Scm -1 at 60°C and an ionic conductivity of 2×10 ^-3 Scm ^-1 at -40°C The conductivity was 0.2×10 ^-3 S cm ^-1 .

The positive pole piece, the separator and the lithium tape are wound into a 26500 cylindrical battery, and the electrolyte is added according to the ratio of E/S=4mL:1g to obtain a primary lithium-sulfur battery. The energy density of the primary lithium-sulfur battery is 280Wh kg ^-1 .

As can be seen from Figure 1-3, the present invention sets the addition ratio (E/S) of the electrolyte to the elemental sulfur to be (0.2-3) mL:1g, and the electrolyte contains acetonitrile, and the obtained primary lithium-sulfur battery is the same as the Compared with ordinary primary lithium-sulfur batteries, it has very excellent electrical properties.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (10)

1. a high specific energy primary lithium-sulfur battery, the battery comprises a negative electrode, a positive electrode, a diaphragm and an electrolyte, wherein the positive electrode is made of a sulfur-carbon composite positive electrode material, and the sulfur-carbon composite positive electrode material comprises sulfur A simple substance, conductive carbon black and a binder, the electrolyte solution comprises a lithium salt, a solvent and a diluent, the solvent is acetonitrile, and the addition ratio of the electrolyte solution to the elemental sulfur is (0.2-3) mL:1 g. 2 . The high specific energy primary lithium-sulfur battery according to claim 1 , wherein the conductive carbon black is selected from one or more of Ketjen black, acetylene black or Super P. 3 . 3. a kind of high specific energy primary lithium-sulfur battery according to claim 1, is characterized in that, in described sulfur-carbon composite positive electrode material, the mass ratio of described sulfur element, conductive carbon black and polytetrafluoroethylene is ( 30~95):(3~40):(2~10). 4. a kind of high specific energy primary lithium-sulfur battery according to claim 1, is characterized in that, described sulfur-carbon composite positive electrode material is prepared by following preparation method: (a) Mixing elemental sulfur and conductive carbon black uniformly, then sealing and sintering in an inert atmosphere to obtain a cathode material precursor; (b) adding the positive electrode material precursor and the binder obtained in the step (a) into ethanol, stirring uniformly, to obtain a positive electrode material crude product; (c) repeating the roll forming of the crude positive electrode material obtained in step (b), followed by drying, to obtain the sulfur-carbon composite positive electrode material. 5 . The high specific energy primary lithium-sulfur battery according to claim 4 , wherein in step (a), the sintering temperature is 140-170° C., and the sintering time is 10-14 h. 6 . 6. a kind of high specific energy primary lithium-sulfur battery according to claim 4, is characterized in that, in step (c), the drying process is specifically: first hang the positive electrode material crude product after rolling to dry, and then place the Dry at 60～80℃ for 8～18h. 7 . The high specific energy primary lithium-sulfur battery according to claim 1 , wherein the lithium salt is lithium bistrifluoromethanesulfonimide, and the diluent is hydrofluoroether. 8 . 8. A high specific energy primary lithium-sulfur battery according to claim 7, wherein the hydrofluoroether is selected from 1,1,2,2-tetrafluoroethyl-2,2,3,3 - one of tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether or 1,1,2,2-tetrafluoroethylethyl ether one or more. 9 . The high specific energy primary lithium-sulfur battery according to claim 1 , wherein, in the electrolyte, the molar ratio of the acetonitrile to the lithium salt is (1～9): 1, and the acetonitrile The volume ratio to the diluent is (4~9):(1~6). 10. An application of the high specific energy primary lithium-sulfur battery according to any one of claims 1-9.

Images