CN115064677B - High-energy-density lithium sulfur battery with polyquaternary ammonium salt as binder - Google Patents
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Abstract
The invention discloses a high-energy density lithium sulfur battery taking polyquaternary ammonium salt as a binder, wherein the polyquaternary ammonium salt is applied to the lithium sulfur battery, and the polyquaternary ammonium salt structure contains cationic groups (- (CH) 3 ) 3 N + ) The catalyst has strong adsorption effect on polysulfide anions of intermediate products generated in the electrochemical reaction process of the lithium-sulfur battery, thereby reducing the loss of active substances and reducing the capacity attenuation of the lithium-sulfur battery. Meanwhile, the polyquaternary ammonium salt has excellent moisturizing performance, so that the pole piece has excellent moisturizing performance on electrolyte, the ion transmission of the electrolyte is promoted, and the stable and circulating operation of the lithium-sulfur battery under the condition of low electrolyte consumption is ensured. In addition, when the polyquaternary ammonium salt is taken as a solvent, the adhesive property is extremely strong, a self-supporting film can be formed under the condition that the mass proportion of the polyquaternary ammonium salt pole pieces is extremely low, the use of a current collector is eliminated, the overall quality in a battery system is reduced, and the stable and cyclic operation of the lithium-sulfur battery under the condition of no current collector is ensured.
Description
Technical Field
The invention belongs to the technical field of battery materials, and particularly relates to a polyquaternium serving as a binder for a lithium-sulfur battery, which has the effects of moisturizing and nourishing electrolyte, enhancing ion transmission in the electrolyte, adsorbing polysulfide anions, constructing a pole piece self-support and the like.
Background
The lithium battery is used as a high-efficiency energy storage system and is always involved in the important process of ecological evolution of energy,lithium ion batteries have been dominant in this process over the last decades. However, the high cost of lithium ion batteries and the current state of becoming closer to the theoretical limit have led us to seek new energy storage batteries with higher energy densities and greater commercial value to meet the current growing energy demands. The lithium-sulfur battery is a lithium battery with metallic lithium as a negative electrode and sulfur element as a positive electrode. Because the lithium-sulfur battery closed system is similar to a lithium ion battery, the conversion from a lithium-sulfur battery to a lithium ion battery is simpler and more efficient in battery manufacturing and is more commercially viable. Secondly, the positive active material elemental sulfur of the lithium sulfur battery has little influence on the environment and human beings, is one of the most abundant elements on the earth, and ensures that the elemental sulfur has low average price of $0.25 kg only -1 This is not enough for LiCoO, the positive electrode material of lithium ion batteries 2 (average price $40 kg -1 ) One percent of the price, which can greatly reduce the production cost of the battery and solve the problem of high production cost of the current lithium ion battery. At the same time, the lithium cobaltate battery is widely applied to the industry< 150 mAh g -1 And< 300 Wh kg -1 ) In contrast, the lithium sulfur battery has ultrahigh theoretical specific capacity and theoretical specific energy (1675 mAh g -1 And 2600 Wh kg -1 ) The current situation that the lithium ion battery is approaching to the theoretical limit can be well solved. In view of this, lithium sulfur batteries are a very promising energy storage battery. However, lithium sulfur batteries have not been commercialized on a large scale for two major reasons: (1) Active material S, li of lithium sulfur battery 2 S 2 And Li (lithium) 2 S poor conductivity makes them poorly utilized in the electrochemical reaction process; (2) Electrochemical intermediate product lithium polysulfide (Li 2 S n N=4, 6, 8) is very soluble in the electrolyte, resulting in loss of active material.
Compounding sulfur with metal oxides, conductive polymers, organic frameworks, various forms of carbon materials, and the like is a common approach to improving the conductivity of sulfur and the adsorption capacity or electrocatalytic activity of polysulfides. Wherein the carbon material has high conductivity, large specific surface area, controllable pore diameter, electron affinity for S and polysulfideThe adsorption capacity of the material is a common additive material for lithium-sulfur batteries. However, in the past work, researchers have often added a large amount of conductive carbon #>30 wt%) to increase the conductivity of the positive electrode, whereas commercial lithium ion batteries have a carbon content of only 5wt%. This results in a huge positive electrode void fraction of the lithium sulfur battery>70 vol%) and thus far compared with lithium ion battery (the ratio of the volume of electrolyte to the mass of positive electrode active material (E/AM) to 0.3 [ mu ] L mg −1 ) Large electrolyte dosage (E/AM>15 µL mg −1 ) To wet the electrodes and to meet the ionic conductivity required for the cell system. The high electrolyte consumption greatly reduces the energy density of the whole battery system of the lithium-sulfur battery and greatly limits the application of the lithium-sulfur battery. It is important to reduce the amount of electrolyte.
At the same time, the wettability of the electrolyte to the electrode material and the migration ability of the polysulfide ions of the intermediate product under the high concentration of the active substance are particularly important for the lithium-sulfur battery under the condition of low electrolyte consumption. The good infiltration performance can enable the active substances to be well contacted with the electrolyte, so that the ion loss and the ion loss occur. The low electrolyte usage will greatly increase the concentration of polysulfides in the electrolyte during the electrochemical reaction, which will greatly hinder the transfer of ions in the electrolyte and further the electrochemical reaction. The good wetting ability of the electrolyte and the good ion migration ability under high concentration are key to realizing the low electrolyte consumption of the lithium-sulfur battery.
Therefore, there is an urgent need in the art to develop a novel lithium sulfur battery system with high sulfur loading, strong adsorption capacity to polysulfide, strong electrolyte infiltration capacity and fast ion transport, so as to realize low electrolyte usage and high energy density of the lithium sulfur battery. And the lithium sulfur battery system satisfies the preparation method and can be industrially produced.
Disclosure of Invention
Aiming at the defects, the invention aims to establish a high sulfur load and low electrolyte consumption system through the functions of moisturizing and nourishing electrolyte by polyquaternium, enhancing ion transmission in the electrolyte, absorbing polysulfide anions, constructing a pole piece self-supporting and the like,a lithium sulfur battery with high energy density is constructed. At the same time, liquid gallium or TiO is introduced into the self-supporting anode 2 -B 2 O 3 The @ C material plays a role in rapid catalytic conversion of polysulfide, and improves the multiplying power charge-discharge performance of the system.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
1. the invention firstly provides a lithium sulfur battery positive electrode material, which comprises sulfur/carbon nano tube (S/CNT), sulfur gallium compound/carbon nano tube (Ga/S/CNT) and titanium dioxide-diboron trioxide/carbon/sulfur/carbon nano Tube (TiO) 2 -B 2 O 3 /C/S/CNT) material.
Preferably, the preparation method of the positive electrode material S/CNT of the lithium-sulfur battery comprises the following steps:
mixing sulfur powder and Carbon Nano Tube (CNT) according to a certain proportion, and obtaining S/CNT after high-temperature melting.
Preferably, the mass ratio of sulfur powder to CNT is 7:2.5.
Preferably, the preparation method of the positive electrode material Ga/S/CNT of the lithium-sulfur battery comprises the following steps:
step one: after the sulfur powder is melted, adding liquid gallium according to a certain proportion, stirring at a high speed for a period of time after complete melting, and cooling to normal temperature to obtain Ga/S;
preferably, the mass ratio of the sulfur powder to Ga is 10:1;
step two: mixing Ga/S and CNT according to a certain proportion, and obtaining Ga/S/CNT after high-temperature melting.
Preferably, the mass ratio of Ga/S to CNT is 7:2.5.
Preferably, the lithium sulfur battery positive electrode material TiO 2 -B 2 O 3 The preparation method of the/C/S/CNT comprises the following steps:
step one: titanium dioxide (TiO) 2 ) Boric acid (H) 3 BO 3 ) And glucose (C) 6 H 12 O 6 ) Mixing in deionized water according to a certain mass ratio to form a sample solution;
step two: vacuum drying the solution obtained in the step one to obtain a precursor;
step three: placing the precursor obtained in the step two in a tubular furnace, and placing the precursor in N 2 Calcining at 400deg.C for 2 h and then at 700deg.C for 6 h in the atmosphere to obtain black powder, named TiO 2 -B 2 O 3 @C；
Step four: tiO is mixed with 2 -B 2 O 3 Mixing @ C, sulfur powder and CNT according to a certain proportion, and melting at high temperature to obtain TiO 2 -B 2 O 3 /C/S/CNT。
2. The invention provides a self-supporting positive electrode of a lithium sulfur battery, which comprises S/CNT or Ga/S/CNT or TiO 2 -B 2 O 3 The preparation method of the/C/S/CNT and polyquaternium comprises the following steps:
step one: S/CNT or Ga/S/CNT or TiO 2 -B 2 O 3 Mixing the/C/S/CNT with the polyquaternium according to a certain proportion, adding a certain amount of deionized water, and stirring and mixing to obtain uniform slurry;
step two: uniformly coating the slurry obtained in the step one on a polytetrafluoroethylene plate;
step three: and (3) drying the polytetrafluoroethylene plate with the slurry obtained in the step (II), and removing the polytetrafluoroethylene plate to obtain the self-supporting anode of the lithium-sulfur battery.
3. The invention provides a lithium sulfur battery with high energy density, which comprises the following steps:
the self-supporting positive electrode is used as the positive electrode of the lithium sulfur battery with high energy density, the diaphragm is Celgard2400, the metal lithium is used as the negative electrode, and LiTFSI/DMC+DEC with the electrolyte of 1 mol/L contains 1 wt percent of LiNO 3 Additive, wherein the addition amount of electrolyte is E/AM=0.1-15 [ mu ] L mg −1 Namely the ratio of the dosage volume of the electrolyte to the mass of the elemental sulfur in the positive electrode material is 0.1-15 mu L mg -1 Preferably 4 [ mu ] L mg -1 。
The invention applies the polyquaternary ammonium salt to the lithium sulfur battery, and the polyquaternary ammonium salt structure contains cationic groups (- (CH) 3 ) 3 N + ) When the polyquaternary ammonium salt is used as a binder, a film continuously rich in cationic groups is formed on the positive electrode material, and the film has a strong adsorption effect on polysulfide anions of an intermediate product generated in the electrochemical reaction process of the lithium-sulfur battery, so that the loss of active substances and the capacity attenuation of the lithium-sulfur battery are reduced, and the stable and cyclic operation of the lithium-sulfur battery under a high-sulfur loading system is ensured. Meanwhile, the polyquaternary ammonium salt has excellent moisturizing performance, so that the pole piece has excellent moisturizing performance on electrolyte, the ion transmission of the electrolyte is promoted, and the stable and circulating operation of the lithium-sulfur battery under the condition of low electrolyte consumption is ensured. In addition, when the polyquaternary ammonium salt is taken as a solvent, the adhesive property is extremely strong, a self-supporting film can be formed under the condition that the mass proportion of the polyquaternary ammonium salt pole pieces is extremely low, the use of a current collector is eliminated, the overall quality in a battery system is reduced, and the stable and cyclic operation of the lithium-sulfur battery under the condition of no current collector is ensured. The lithium-sulfur battery with high sulfur loading, low electrolyte consumption and self-supporting structure can be constructed together. The polyquaternary ammonium salt has low cost, and when the polyquaternary ammonium salt is used as a binder, the self-supporting film can be formed by directly pouring the solvent serving as water, so that the method has the advantages of low production cost, simplicity and convenience in operation, environmental friendliness and the like, and can realize industrial mass production and application.
The invention has the beneficial effects that:
the invention provides a high-energy-density lithium sulfur battery taking polyquaternary ammonium salt as a binder, which comprises a self-supporting positive electrode formed by strong bonding action of the polyquaternary ammonium salt. Cationic groups (- (CH) contained in the polyquaternium structure 3 ) 3 N + ) Has strong adsorption effect on intermediate polysulfide anions generated in the electrochemical reaction process of a lithium-sulfur battery, and the self-supporting positive electrode is used for carrying 3.38 mg cm of sulfur -2 At the time, the specific capacity of the first discharge reaches 1248.5 mAh g -1 At 1 mA cm -2 The charge and discharge test was performed, and the cycle was stabilized 100 times. Meanwhile, the polyquaternium has excellent moisturizing performance, so that the pole piece has excellent moisturizing performance on electrolyte, promotes ion transmission of the electrolyte, and ensuresThe lithium-sulfur battery stably and circularly works under the condition of low electrolyte consumption, and meanwhile, liquid gallium or TiO is introduced into a self-supporting positive electrode 2 -B 2 O 3 In the case of @ C material as catalyst for electrochemical reactions, the sulfur loading was 6.0 mg cm -2 At the time, the specific capacity of the first discharge reaches 1183.3 mAh g -1 The surface capacity is as high as 7.1 mAh cm -2 The surface capacity of the lithium ion battery is far higher than that of a lithium ion battery (4 mAh cm -2 ). At electrolyte dosage of E/am=4μl mg −1 Under the condition that the relative dosage of lithium is 150%, the constructed lithium-sulfur battery reaches 344.5 Wh kg -1 Is far higher than the energy density of the lithium ion battery (100-200 Wh kg -1 ) Has great application prospect.
The invention takes a polyquaternium aqueous solution as a high-viscosity binder to form a self-supporting anode, and aims to reduce the use of a current collector, thereby improving the overall energy density of a battery, and establishing a stable circulating system under the condition of low electrolyte consumption.
Drawings
FIG. 1 is a self-supporting S/CNT anode.
Fig. 2 is a graph comparing charge-discharge cycle data of lithium-sulfur batteries of aluminum foil positive electrode with PVDF as binder and S/CNT self-supporting positive electrode with polyquaternium as binder.
FIG. 3 shows the first charge and discharge curves of the self-supporting S/CNT anode and the self-supporting Ga/S/CNT anode.
Fig. 4 is a graph of charge-discharge cycle data of a lithium-sulfur battery with a Ga/S/CNT self-supporting cathode.
FIG. 5 is a schematic diagram of a self-supporting S/CNT anode and TiO 2 -B 2 O 3 First charge-discharge curve of the/C/S/CNT self-supporting anode.
FIG. 6 is a diagram of TiO 2 -B 2 O 3 And (3) a charge-discharge cycle data diagram of the lithium-sulfur battery with the C/S/CNT self-supporting positive electrode.
FIG. 7 is a diagram of TiO 2 -B 2 O 3 Energy density diagram of lithium sulfur battery of/C/S/CNT self-supporting positive electrode.
Detailed Description
In order to facilitate understanding of the present invention, the following description will clearly and fully describe the technical solutions of the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The preparation of the lithium-sulfur battery with S/CNT as a positive electrode material and polyquaternium-10 as a binder comprises the following steps:
step one: grinding sulfur powder and CNT according to the mass ratio of 7:2.5, fully mixing, and melting for 3 hours under the protection of inert gas argon at 155 ℃ to obtain S/CNT;
step two: grinding and fully mixing the S/CNT obtained in the first step with polyquaternium-10 according to the mass ratio of 200 mg S/CNT to 10.52 and mg polyquaternium-10, adding a proper amount of deionized water, and fully grinding into slurry;
step three: uniformly coating the slurry obtained in the step two on a polytetrafluoroethylene plate;
step four: drying the polytetrafluoroethylene plate with the slurry obtained in the step three in a vacuum oven at 60 ℃ for 12 h, and then removing the polytetrafluoroethylene plate to obtain the S/CNT self-supporting anode of the lithium-sulfur battery;
a in FIG. 1 is 6.5X6.5 cm of the obtained 2 The S/CNT self-supporting positive electrode shown in the figure 1 b can be curled 180 degrees, and has good flexibility.
Step five: cutting the S/CNT self-supporting anode obtained in the step four into a wafer with the diameter of 12 mm, taking Celgard2400 as a diaphragm, taking metallic lithium as a cathode, and taking 1 mol L of electrolyte -1 LiTFSI/DMC+DEC containing 1 wt% LiNO 3 Additive, electrolyte adding amount is E/AM=4mu L mg −1 Assembling into a lithium sulfur button cell;
step six: under the condition of room temperature, the button cell prepared in the fifth step is tested in LAND cell test systemThe charge and discharge test is carried out on the system, the charge and discharge voltage interval is 1.7-2.8V, and the previous 0.5 mA cm -2 Activated for five circles and 1 mA cm after -2 And performing charge and discharge test under the current density.
Comparative example 1
An S-PVDF positive electrode prepared by coating a conventional binder polyvinylidene fluoride (PVDF) on an aluminum foil was prepared as a blank control group of the above example, comprising the steps of:
step one: grinding sulfur powder and CNT according to the mass ratio of 7:2.5, fully mixing, and melting for 3 hours under the protection of inert gas argon at 155 ℃ to obtain S/CNT;
step two: grinding and fully mixing the S/CNT obtained in the step one with PVDF according to the mass ratio of 200 mg S/CNT to 10.52 mg PVDF, adding a proper amount of N-methylpyrrolidone, and fully grinding into slurry;
step three: uniformly coating the slurry obtained in the step two on an aluminum foil;
step four: drying the aluminum foil with the slurry obtained in the step three in a vacuum oven at 60 ℃ for 12 h to obtain the S-PVDF aluminum foil anode of the lithium sulfur battery;
step five: cutting the S-PVDF aluminum foil anode obtained in the step four into a circular sheet with the diameter of 12 mm, taking Celgard2400 as a diaphragm, taking metallic lithium as a cathode, and 1 mol L of electrolyte -1 LiTFSI/DMC+DEC containing 1 wt% LiNO 3 Additive, electrolyte adding amount is E/AM=4mu L mg −1 Assembling into a lithium sulfur button cell;
step six: under the condition of room temperature, the button battery prepared in the fifth step is subjected to charge and discharge test on a LAND battery test system, wherein the charge and discharge voltage interval is 1.7-2.8V, and the previous 0.5 mA cm -2 Activated for five circles and 1 mA cm after -2 And performing charge and discharge test under the current density.
FIG. 2 is a graph showing that the S-PVDF prepared in comparative example 1 and the S/CNT prepared in example 1 are positive electrode materials in a lithium sulfur battery of 1 mA cm -2 Comparison of the cyclic data graph of charge and discharge tests at current density at low electrolyte usage E/am=4 μl mg −1 Sulfur loading of 3.5 mg cm -2 When the discharge capacity of the first circle of the S-PVDF positive electrode is only 2 mAh cm -2 、577.1 mAh g -1 The subsequent rapid decay of the cycling capacity to zero, it can be seen that the lithium sulfur battery under the condition of low electrolyte dosage is difficult to work normally under the condition of the traditional binder, while the lithium sulfur battery with S/CNT as the positive electrode material has a sulfur load of 3.4 mg cm -2 At the time, the specific capacity of the first discharge is up to 4.24 mAh cm -2 、1248.5 mAh g -1 The coulombic efficiency is 99.5%, the polyquaternium-10 ensures that the lithium sulfur battery stably works under the condition of low electrolyte consumption, and 840.2 mAh g is kept after the lithium sulfur battery is stably circulated for 100 times -1 The specific capacity of the poly quaternary ammonium salt-10 is reflected to have strong adsorption effect on intermediate polysulfide anions generated in the electrochemical reaction process of the lithium sulfur battery, and the stable and circular operation of the lithium sulfur battery system is ensured.
Example 2
The preparation of the lithium sulfur battery with Ga/S/CNT as a positive electrode material and polyquaternium-10 as a binder comprises the following steps:
step one: placing sulfur powder into a polytetrafluoroethylene reaction tank, heating an oil bath to 144 ℃ to melt the sulfur powder, adding liquid gallium according to the mass ratio of the liquid gallium to the sulfur powder of 1:10, stirring by adopting a motor after complete melting, and rotating at 1200 r min -1 Stirring at constant temperature and high speed for 3h, and cooling to normal temperature to obtain Ga/S;
step two: grinding and fully mixing the Ga/S obtained in the step one and the CNT according to the mass ratio of 7:2.5, and melting for 3 hours under the protection of inert gas argon at 155 ℃ to obtain Ga/S/CNT;
step three: grinding and fully mixing the Ga/S/CNT obtained in the second step and polyquaternium-10 according to the mass ratio of 400 mg Ga/S/CNT and 21.05 mg polyquaternium-10, adding a proper amount of deionized water, and fully grinding into slurry;
step four: uniformly coating the slurry obtained in the step three on a polytetrafluoroethylene plate;
step five: drying the polytetrafluoroethylene plate with the slurry obtained in the step four in a vacuum oven at 60 ℃ for 12 h, and then removing the polytetrafluoroethylene plate to obtain the Ga/S/CNT self-supporting anode of the lithium-sulfur battery;
step six: cutting the Ga/S/CNT self-supporting anode obtained in the step five into a wafer with the diameter of 12 mm, taking Celgard2400 as a diaphragm, taking metallic lithium as a cathode, and taking 1 mol L of electrolyte -1 LiTFSI/DMC+DEC containing 1 wt% LiNO 3 Additive, electrolyte adding amount is E/AM=4mu L mg −1 With E/am=3.5 μl mg −1 Assembling into a lithium sulfur button cell;
step seven: under the condition of room temperature, performing charge and discharge test on the button cell prepared in the step six on a LAND cell test system, wherein the charge and discharge voltage interval is 1.7-2.8V, and the previous 0.5 mA/cm 2 Activated five times, after 1 mA/cm 2 And performing charge and discharge test under the current density.
FIG. 3 is a first charge-discharge curve comparison of the self-supporting S/CNT anode and the self-supporting Ga/S/CNT anode, wherein the self-supporting S/CNT anode was prepared in the same manner as in example 1 except that the slurry coated on a polytetrafluoroethylene sheet was used in an amount of 400 mg of the sum of S/CNT and 21.05 mg of polyquaternium-10. The voltage difference delta E=0.18 and V between Ga/S/CNT self-supporting positive electrode charge and discharge platforms is far smaller than the voltage difference delta E=0.3 and V between S/CNT self-supporting positive electrode charge and discharge platforms, and excellent catalysis effect of liquid metal Ga on intermediate polysulfide is shown. FIG. 4 shows that the Ga/S/CNT self-supporting anode has a sulfur loading of 6.1 mg cm -2 The electrolyte dosage is E/AM=4 [ mu ] L mg −1 The first discharge specific capacity of the lithium-sulfur battery is up to 1098.4 mAh g -1 The surface capacity is as high as 6.7 mAh cm -2 After 100 cycles of charge and discharge, 3.9 mAh cm still remained -2 Is a high area capacity of (a).
Example 3
TiO (titanium dioxide) 2 -B 2 O 3 The preparation of the lithium sulfur battery with the positive electrode material of/C/S/CNT and the binder of polyquaternium-10 comprises the following steps:
step one: titanium dioxide (TiO) 2 ) Boric acid (H) 3 BO 3 ) And glucose (C) 6 H 12 O 6 ) Mixing in deionized water according to the mass ratio of 0.5:2.5:3 to formA sample solution;
step two: drying the solution obtained in the step one in a vacuum oven at 60 ℃ for 12 h to obtain a precursor;
step three: placing the precursor obtained in the step two in a tubular furnace, and placing the precursor in N 2 Calcining at 400deg.C for 2 h and then at 700deg.C for 6 h in the atmosphere to obtain black powder, named TiO 2 -B 2 O 3 @C；
Step four: the TiO obtained in the step three is treated 2 -B 2 O 3 Grinding and fully mixing @ C and sulfur powder according to the mass ratio of 1:3 to obtain TiO 2 -B 2 O 3 Grinding and fully mixing @ C/S and CNT (carbon nano tube) according to the mass ratio of 7:2.5, and melting for 3 hours under the protection of inert gas argon at 155 ℃ to obtain TiO 2 -B 2 O 3 /C/S/CNT；
Step five: the TiO obtained in the step four is treated 2 -B 2 O 3 Grinding and fully mixing/C/S/CNT and polyquaternium-10 according to the mass ratio of 400 mg Ga/S/CNT and 21.05 mg polyquaternium-10, adding proper amount of deionized water, and fully grinding into slurry;
step six: uniformly coating the slurry obtained in the step five on a polytetrafluoroethylene plate;
step seven: drying the polytetrafluoroethylene plate with the slurry obtained in the step six in a vacuum oven at 60 ℃ for 12 h, and then removing the polytetrafluoroethylene plate to obtain the TiO of the lithium-sulfur battery 2 -B 2 O 3 a/C/S/CNT self-supporting positive electrode;
step eight: the TiO obtained in the step seven 2 -B 2 O 3 Cutting a self-supporting anode of/C/S/CNT into a wafer with the diameter of 12 mm, taking Celgard2400 as a diaphragm, taking metallic lithium as a cathode, and 1 mol L of electrolyte -1 LiTFSI/DMC+DEC containing 1 wt% LiNO 3 Additive, electrolyte adding amount is E/AM=4mu L mg −1 With E/am=3.5 μl mg −1 Lithium sulfur button cells were assembled for testing electrochemical performance.
FIG. 5 is a schematic diagram of a self-supporting S/CNT anode and TiO 2 -B 2 O 3 A first charge-discharge curve comparison of the self-supporting positive electrode of/C/S/CNT, wherein the preparation method of the self-supporting positive electrode of S/CNT was the same as in example 1 except that the slurry coated on the polytetrafluoroethylene sheet was used in an amount of 400 mg of S/CNT together with 21.05. 21.05 mg of polyquaternium-10. TiO (titanium dioxide) 2 -B 2 O 3 The voltage difference delta E=0.18V between the charging and discharging platforms of the self-supporting anode of the/C/S/CNT is far smaller than the voltage difference delta E=0.3V between the charging and discharging platforms of the self-supporting anode of the S/CNT, thus reflecting the liquid metal TiO 2 -B 2 O 3 Excellent catalytic effect on intermediate polysulfides. FIG. 6 is a diagram of TiO 2 -B 2 O 3 The sulfur loading of the self-supporting anode of/C/S/CNT was 6.0 mg cm -2 The electrolyte dosage is E/AM=4 [ mu ] L mg −1 The first discharge specific capacity of the lithium-sulfur battery is up to 1183.3 mAh g -1 The surface capacity is as high as 7.1 mAh cm -2 After 100 cycles of charge and discharge, the material still remains 4.5 mAh cm -2 Is a high area capacity of (a).
FIG. 7 is a diagram of TiO 2 -B 2 O 3 The relative dosage of the self-supporting anode of the/C/S/CNT in lithium is 150%, and the sulfur loading is 6.0 mg cm -2 The electrolyte dosage is E/AM=4 [ mu ] L mg −1 The following lithium sulfur battery mass energy density cycle data graph, energy density (E g ) The method can be calculated by the formula: e (E) g = VC/∑M i . Where V is the average output voltage (2.1V) and C is the area capacity (mAh cm -2 ），M i Is the unit square mass (mg cm) of the battery assembly (including positive electrode, negative electrode (1.5 times lithium), separator and electrolyte) -2 ). The energy density of the first discharge mass is up to 344.5 Wh kg -1 After 100 charge and discharge cycles, 217.6 Wh kg remained -1 Is far higher than that of the positive electrode material of commercial lithium ion battery (100-200 Wh kg -1 ）。
The foregoing description is only of the preferred embodiments of the invention, and all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (5)
1. The high-energy-density lithium sulfur battery taking the polyquaternary ammonium salt as the binder is characterized in that a self-supporting film formed by taking the polyquaternary ammonium salt as the binder is taken as a positive electrode;
mixing the positive electrode material with the binder polyquaternium according to a certain proportion, adding a certain amount of water to prepare slurry, directly pouring the slurry on a polytetrafluoroethylene plate, drying, and removing the slurry from the polytetrafluoroethylene plate to obtain a self-supporting film serving as a positive electrode of the lithium-sulfur battery;
the composition of the positive electrode material comprises liquid gallium or TiO 2 -B 2 O 3 @C, a carbon nanotube and a sulfur source;
the preparation method of the positive electrode material comprises the following steps: liquid gallium or TiO metal 2 -B 2 O 3 And C, melting the carbon nano tube and a sulfur source at high temperature.
2. The high energy density lithium sulfur battery of claim 1 wherein the TiO 2 -B 2 O 3 The preparation method of the @ C material comprises the following steps:
(1) Mixing titanium dioxide, boric acid and glucose in deionized water according to a certain mass ratio to form a sample solution;
(2) Vacuum drying the solution obtained in the step (1) to obtain a precursor;
(3) Placing the precursor obtained in the step (2) in a tubular furnace, and then placing the precursor in N 2 Calcining at 400deg.C for 2 h and then at 700deg.C for 6 h in the atmosphere to obtain black powder, named TiO 2 -B 2 O 3 @C。
3. The high energy density lithium sulfur battery of claim 1 wherein said lithium sulfur battery comprises metallic lithium as the negative electrode.
4. The high energy density lithium sulfur battery of claim 1 wherein the lithium sulfur battery comprises a solution of lithium bistrifluoromethane sulfonyl imide as an electrolyte.
5. The lithium sulfur battery with high energy density according to claim 4, wherein the lithium sulfur battery uses a low electrolyte dosage, and the ratio of the electrolyte dosage volume to the mass of elemental sulfur in the positive electrode material is 0.1-15 [ mu ] L mg -1 。
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| KR20030006744A (en) * | 2001-07-14 | 2003-01-23 | 주식회사 뉴턴에너지 | Electrochemical Cells with anionic polymers |
| CN107579200A (en) * | 2016-07-04 | 2018-01-12 | 杭州聚力氢能科技有限公司 | A kind of full encapsulation sulfur electrode |
| CN108493411A (en) * | 2018-03-14 | 2018-09-04 | 东华大学 | Lithium sulfur battery anode material and cationic lithium-sulfur cell binder |
| CN113692661A (en) * | 2019-11-06 | 2021-11-23 | 株式会社Lg新能源 | Binder for lithium secondary battery electrode, positive electrode for lithium secondary battery comprising same, and lithium secondary battery |
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| KR20030006744A (en) * | 2001-07-14 | 2003-01-23 | 주식회사 뉴턴에너지 | Electrochemical Cells with anionic polymers |
| CN107579200A (en) * | 2016-07-04 | 2018-01-12 | 杭州聚力氢能科技有限公司 | A kind of full encapsulation sulfur electrode |
| CN108493411A (en) * | 2018-03-14 | 2018-09-04 | 东华大学 | Lithium sulfur battery anode material and cationic lithium-sulfur cell binder |
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