Molten salt electrolyte and preparation method thereof, fast-chargeable aluminum-sulfur battery and application thereof

Abstract

The present invention relates to the technical field of aluminum-sulfur batteries, and in particular to a molten salt electrolyte and a preparation method thereof, a fast-chargeable aluminum-sulfur battery and its application. The molten salt electrolyte comprises a general formula A a AlX b A molten salt; wherein A is selected from at least one of Ca, Mg, Li, Na, K, Rb and Cs; X includes at least two different halogen elements; 0.1≤a≤1, 3.1≤b≤4. The present invention improves the disorder and asymmetry of the molten salt electrolyte by introducing at least two different types of halogen elements, reduces the bond breaking energy barrier of the aluminum-halogen covalent bond, and realizes the fast reaction kinetics of the molten salt electrolyte, thereby realizing the high capacity and fast charging performance of the aluminum-sulfur battery. In addition, the melting point of the molten salt electrolyte is low.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum-sulfur batteries, and specifically, to a molten salt electrolyte and a preparation method thereof, a fast-chargeable aluminum-sulfur battery and applications thereof; more specifically, to a molten salt electrolyte and a preparation method thereof, a fast-chargeable aluminum-sulfur battery, an energy storage device and applications thereof. Background Art

[0002] Large-scale electrochemical energy storage technology is urgently needed in the fields of power grid frequency regulation and peak regulation, solar power stations, wind power stations, reserve power sources, smart microgrids, communication base stations and new energy electric vehicles. Current lithium-ion batteries use flammable organic electrolytes and are limited by the high cost and limited energy storage of lithium elements, making it difficult to achieve large-scale utilization. Rechargeable aluminum batteries are a promising new generation of energy storage systems due to the low cost, high content of crustal elements and high specific capacity of aluminum negative electrodes. Sulfur positive electrodes are an ideal positive electrode choice in high-performance rechargeable aluminum batteries due to their large theoretical capacity and high resource abundance.

[0003] Due to Al 3+ Due to the small size and complex three-electron reaction, existing aluminum-sulfur batteries mainly use conventional room temperature ionic liquid electrolytes. However, aluminum-sulfur batteries using room temperature ionic liquids face slow sulfur conversion reaction kinetics, showing poor rate performance (generally C / 20~C / 10) and an overpotential of up to 0.75V, which greatly reduces their energy density and energy efficiency. This low kinetic reaction can be attributed to the high energy barrier associated with the dissociation of aluminum ion clusters in the electrolyte, and the resulting difficulty in the sulfur conversion reaction. In addition, the high cost of room temperature ionic liquids also restricts the large-scale practical application of aluminum-sulfur batteries.

[0004] In addition, the preparation of aluminum ion electrolytes with high reaction kinetics, so that the sulfur cathode can achieve high specific capacity and rate performance in aluminum-sulfur batteries, is a prerequisite for achieving aluminum-sulfur batteries with high energy density and power density. Conventional aluminum-sulfur batteries can only achieve reversible cycles under conditions of very low sulfur surface loading and low current density, which leads to the low energy density and power density of aluminum-sulfur batteries, making them difficult to apply. In haloaluminate electrolytes, Al covalently bound to halogens 3+ The charge and discharge process of aluminum-sulfur batteries can only be realized by dissociating from the polyanions in aluminates. However, the bond breaking energy barrier of the highly ordered and highly symmetrical aluminum-halogen covalent bonds is usually high, which determines the desolvation ability of the electrolyte. Existing electrolytes are difficult to achieve high reaction kinetics.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first purpose of the present invention is to provide a molten salt electrolyte. By introducing at least two halogen elements, the active ion / molecular group type of the molten salt electrolyte is changed. The synergistic effect of multiple halogens increases the disorder and asymmetry of the ion / molecular group, reduces the bond breaking energy barrier of the aluminum-halogen covalent bond, and realizes the fast reaction kinetics of the molten salt electrolyte. On the one hand, it solves the problem of poor kinetics faced by aluminum metal batteries based on room temperature ionic liquids, and on the other hand, it solves the kinetic problem of high aluminum-chlorine bond breaking potential barrier faced by single chloride molten salt electrolytes.

[0007] The second object of the present invention is to provide a method for preparing a molten salt electrolyte, which has the advantages of simple operation, short process flow, low preparation cost and suitability for mass production.

[0008] The third object of the present invention is to provide a fast-chargeable aluminum-sulfur battery, which can accelerate the electrochemical reaction kinetics by adopting a specific molten salt electrolyte, thereby achieving high capacity and fast charging performance of the fast-chargeable aluminum-sulfur battery.

[0009] A fourth object of the present invention is to provide an energy storage device.

[0010] The fifth object of the present invention is to provide the application of the energy storage device as described above in power grid frequency and peak regulation, solar power stations, wind power stations, reserve power sources, smart microgrids, communication base stations and new energy electric vehicles.

[0011] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0012] The present invention provides a molten salt electrolyte, comprising a general formula A a AlX b of molten salt.

[0013] Wherein, the molten salt is a homogeneous single-phase liquid at a temperature higher than its melting point. a AlX b is a nominal general formula, representing the corresponding proportions of the corresponding elements in the molten salt, and does not necessarily refer to pure substances. The general formula complies with the principle that the algebraic sum of the positive and negative valences of each element is zero. In addition, the general formula A a AlX b a and b are the mole fractions of the corresponding elements, that is, 1 mole of A a AlX b It contains a moles of element A, 1 mole of element Al and b moles of element X.

[0014] Wherein, A is selected from at least one of Ca, Mg, Li, Na, K, Rb and Cs; X includes at least two different halogen elements; 0.1≤a≤1, 3.1≤b≤4.

[0015] When A a AlX b When a<0.1 and b<3.1 in the general formula, the molten salt contains a large amount of highly volatile aluminum halide, so the molten salt electrolyte is highly volatile and cannot be used normally as an electrolyte.

[0016] The molten salt electrolyte provided by the present invention changes the type of active ion / molecular groups of the molten salt electrolyte by introducing at least two different types of halogen elements. The synergistic effect of multiple halogens increases the disorder and asymmetry of the ion / molecular groups, reduces the bond breaking energy barrier of the aluminum-halogen covalent bond, and realizes the fast reaction kinetics of the molten salt electrolyte, thereby achieving the high capacity and fast charging performance of the aluminum-sulfur battery.

[0017] In some specific embodiments of the present invention, the general formula A a AlX b A in the above-mentioned may be selected from any one of Ca, Mg, Li, Na, K, Rb and Cs, or any combination of two or more thereof. Preferably, the above-mentioned A is selected from at least two or at least three of Ca, Mg, Li, Na, K, Rb and Cs.

[0018] In some specific embodiments of the present invention, the halogen element includes at least one of F, Cl, Br and I.

[0019] In some specific embodiments of the present invention, the general formula A a AlX b In the formula A, at least two or more of the following may be selected: F, Cl, Br and I. a AlX b X in the above-mentioned is selected from at least two of Cl, Br and I, or a combination of Cl, Br and I.

[0020] In some specific embodiments of the present invention, the general formula A a AlX b a includes but is not limited to any one of 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.53, 0.55, 0.58, 0.6, 0.63, 0.64, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.79, 0.8, 0.85, 0.9, 0.95, 1 or any range between two thereof; preferably 0.25 to 1.

[0021] In some specific embodiments of the present invention, the general formula A a AlX b The b in the above description includes but is not limited to any one of 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.45, 3.5, 3.55, 3.6, 3.64, 3.65, 3.7, 3.75, 3.78, 3.79, 3.8, 3.85, 3.9, 3.95, and 4, or a range between any two of them; preferably, 3.3 to 4.

[0022] When the molten salt electrolyte contains two or more different halogen elements, the active ions / molecular groups with electrochemical activity generated after the electrolyte melts are completely different from those of the molten salt electrolyte of a single halogen, so the ion desolvation ability and the working mechanism of the reaction during actual operation of the electrolyte are also different. Specifically, for example, when the molten salt electrolyte contains only Cl, the active ions / molecular groups generated after a series of chemical equilibrium reactions include Al2Cl6, Al2Cl7 - , Al3Cl 10 - , Al4Cl 13 - etc. (such as Figure 1 For example, when the molten salt electrolyte contains two halogens, Cl and Br, the active ions / molecules produced by a series of chemical equilibrium reactions after melting include Al2Cl5Br, Al2Cl6Br - , Al3Cl8Br2 - , Al4Cl 10 Br3 - etc. (such as Figure 1 As shown), the specific active ingredients of the electrolyte are different.

[0023] The molten salt electrolyte, by introducing a variety of halogens, on the one hand, increases the disorder of the aluminum-halogen bonding system of the molten salt electrolyte, and the increase in system entropy leads to a larger change in the Gibbs free energy of the bond breaking reaction of the aluminum-halogen bridging bond (that is, ΔG is more negative), which makes it easier to break the bond thermodynamically. On the other hand, since aluminum atoms and different halogens undergo mixed coordination through chemical reactions with different bond lengths, the synergistic effect of multiple halogens greatly increases the asymmetry of the active ion / molecular group, resulting in an asymmetric distribution of the electron cloud density of the aluminum-halogen bond. Therefore, relative to the symmetrical ion / molecular group of a single halogen, the bond breaking barrier of the aluminum-halogen bridging bond is lower. Aluminum-halogen bonds are more easily broken under electric field drive, and aluminum ions have a stronger desolvation ability. The specific desolvation pathway is: active Al n X 3n+1 -The ions first break the bridging Al-X bonds to form basic units Al2X6 and Al2X7 - or AlX4 - , then Al2X7 - In the same way, the bonds are broken to form Al2X6 and AlX4 - , Al2X6 then breaks the bridging Al-X bond, and finally generates Al 3+ and AlX4 - . With Al3X 10 - For example, the reaction is:

[0024] Al4X 13 - →Al2X7 - +Al2X6

[0025] 2Al2X7 - →AlX4 - +Al2X6

[0026] Al2X6→AlX4 - +AlX2 +

[0027] AlX2 + →AlX4 - +Al 3+

[0028] The present invention promotes the breaking of Al-X bridging bonds by introducing multiple halogens, and achieves fast reaction kinetics, thereby achieving high capacity and fast charging performance of aluminum-sulfur batteries. It should be noted that when the molten salt electrolyte introduces three halogens, this effect is stronger than that of the molten salt electrolyte introducing two halogens, and the reaction kinetics is faster.

[0029] Preferably, the molten salt electrolyte comprises a general formula A a Y c Z d of molten salt.

[0030] The general formula A a Y c Z d It complies with the principle that the algebraic sum of the positive and negative valences of each element is zero. a Y c Z d a, c, and d are the mole fractions of the corresponding elements, that is, 1 mole of A a Y c Z d It contains a moles of element A, 1 mole of element Al, c moles of element Y and d moles of element Z.

[0031] Wherein, A is selected from at least one of Ca, Mg, Li, Na, K, Rb and Cs; Y and Z are each independently selected from one of F, Cl, Br and I, and Y and Z are two different halogen elements; 0.1≤a≤1, 0.001≤c≤4, 0.001≤d≤4.

[0032] In some specific embodiments of the present invention, the general formula A a Y c Z d A in the above-mentioned may be selected from any one of Ca, Mg, Li, Na, K, Rb and Cs, or any combination of two or more thereof. Preferably, the above-mentioned A is selected from at least two or at least three of Ca, Mg, Li, Na, K, Rb and Cs.

[0033] In some specific embodiments of the present invention, when the general formula A a Y c Z d When Y in the formula is selected from F, Z can be selected from one of Cl, Br or I; when the general formula A a Y c Z d When Y in the formula is selected from Cl, Z can be selected from one of F, Br or I; when the general formula A a Y c Z d When Y in the formula is selected from Br, Z can be selected from one of F, Cl or I; when the general formula A a Y c Z d When Y in is selected from I, Z can be selected from one of F, Cl or Br.

[0034] In some specific embodiments of the present invention, the general formula A a Y c Z d a includes but is not limited to any one of 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.53, 0.55, 0.58, 0.6, 0.63, 0.64, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.79, 0.8, 0.85, 0.9, 0.95, 1 or any range between two thereof; preferably 0.25 to 1.

[0035] In some specific embodiments of the present invention, the general formula A a Y c Z dThe c in this example includes, but is not limited to, 0.002, 0.003, 0.004, 0.005, 0.007, 0.009, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.14, 0.2, 0.21, 0.3, 0.32, 0.5, 0.54, 0.7, 0.9, 1, 1.3, 1.5, 1.8, 2, 2.2, 2.5, 2. 8, 3, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.43, 3.45, 3.46, 3.5, 3.55, 3.6, 3.61, 3.64, 3.65, 3.7, 3.75, 3.78, 3.79, 3.8, 3.85, 3.9, 3.95, any one of the point values ​​or the range value between any two of them; preferably 0.1-4.

[0036] In some specific embodiments of the present invention, the general formula A a Y c Z d The d in the example includes, but is not limited to, 0.002, 0.003, 0.004, 0.005, 0.007, 0.009, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.14, 0.2, 0.21, 0.3, 0.32, 0.5, 0.54, 0.7, 0.9, 1, 1.3, 1.5, 1.8, 2, 2.2, 2.5, 2.8 , 3.3, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.43, 3.45, 3.46, 3.5, 3.55, 3.6, 3.61, 3.64, 3.65, 3.7, 3.75, 3.78, 3.79, 3.8, 3.85, 3.9, 3.95, any one of the point values ​​or the range value between any two of them; preferably 0.1-3.9.

[0037] Preferably, 0.25≤a≤1.

[0038] Preferably, c≥d. More preferably, c>d.

[0039] Preferably, d: (c+d) = 0.001 to 0.5.

[0040] In some specific embodiments of the present invention, the value of d: (c + d) includes but is not limited to 0.001, 0.002, 0.003, 0.037, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.058, 0.06, 0.07, 0.08, 0.085, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.42, 0.45, 0.47, or any range between two thereof. More preferably, d: (c + d) = 0.002 to 0.4.

[0041] The present invention provides a molten salt electrolyte with polyhalogen anions. The synergistic effect of polyhalogens increases the disorder and asymmetry of ion / molecular active groups, can reduce the bond breaking energy barrier of aluminum-halogen covalent bonds, and promote the dissociation and desolvation of aluminum, thereby achieving rapid reaction kinetics of the molten salt electrolyte.

[0042] Preferably, the molten salt electrolyte comprises a general formula A a Y c Z d W e of molten salt.

[0043] The general formula A a Y c Z d W e It complies with the principle that the algebraic sum of the positive and negative valences of each element is zero. a Y c Z d W e a, c, d, and e are the mole fractions of the corresponding elements, that is, 1 mole of A a Y c Z d W e It contains a moles of element A, 1 mole of element Al, c moles of element Y, d moles of element Z and e moles of element W.

[0044] Wherein, A is selected from at least one of Ca, Mg, Li, Na, K, Rb and Cs; Y, Z and W are each independently selected from one of F, Cl, Br and I, and Y, Z and W are three different halogen elements; 0.1≤a≤1, 0.001≤c≤4, 0.001≤d≤4, 0.0001≤e≤4.

[0045] By setting three different types of halogen elements, the disorder of aluminum-halogen-based ions in the molten salt electrolyte can be further improved. The large-sized halogens among the three halogens can further promote the delocalization of the electron cloud, and the asymmetric properties brought by the synergistic effect of the three halogens are beneficial to further reduce the bond breaking energy barrier of the aluminum-halogen covalent bond, promote the dissociation and desolvation of aluminum, and improve the reaction kinetics.

[0046] In some specific embodiments of the present invention, the general formula A a Y c Z d W e A in the formula (A) may be selected from any one of Ca, Mg, Li, Na, K, Rb and Cs, or any combination of two or more thereof. Preferably, A is selected from at least two of Ca, Mg, Li, Na, K, Rb and Cs. More preferably, A is selected from at least three of Ca, Mg, Li, Na, K, Rb and Cs.

[0047] In some specific embodiments of the present invention, the general formula A a Y c Z d W e Y, Z and W in the above are each independently selected from one of Cl, Br and I, and the three elements of Y, Z and W are different. For example, when Y is Cl, Z is Br and W is I; or, when Y is Cl, Z is I and W is Br; or, when Y is Br, Z is Cl and W is I; or, when Y is Br, Z is I and W is Cl; or, when Y is I, Z is Br and W is Cl; or, when Y is I, Z is Cl and W is Br.

[0048] In some specific embodiments of the present invention, the general formula A a Y c Z d W e a includes but is not limited to any one of 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.53, 0.55, 0.58, 0.6, 0.63, 0.64, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.79, 0.8, 0.85, 0.9, 0.95, 1 or any range between two thereof; preferably 0.25 to 1.

[0049] In some specific embodiments of the present invention, the general formula A a Y c Z d W eThe c in this example includes, but is not limited to, 0.001, 0.002, 0.003, 0.004, 0.005, 0.007, 0.009, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.14, 0.2, 0.21, 0.3, 0.32, 0.5, 0.54, 0.7, 0.9, 1, 1.3, 1.5, 1.8, 2, 2.2, 2.5, Any one of the point values ​​among 2.8, 3, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.43, 3.45, 3.46, 3.5, 3.55, 3.6, 3.61, 3.64, 3.65, 3.7, 3.75, 3.78, 3.79, 3.8, 3.85, 3.9, 3.95, 4, or a range value between any two thereof; preferably 0.04 to 4.

[0050] In some specific embodiments of the present invention, the general formula A a Y c Z d W e The d in this example includes, but is not limited to, 0.001, 0.002, 0.003, 0.004, 0.005, 0.007, 0.009, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.14, 0.2, 0.21, 0.3, 0.32, 0.5, 0.54, 0.7, 0.9, 1, 1.3, 1.5, 1.8, 2, 2.2, 2.5, 2 .8, 3, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.43, 3.45, 3.46, 3.5, 3.55, 3.6, 3.61, 3.64, 3.65, 3.7, 3.75, 3.78, 3.79, 3.8, 3.85, 3.9, 3.95, any one of the point values ​​or the range value between any two of them; preferably 0.04 to 3.9.

[0051] In some specific embodiments of the present invention, the general formula A a Y c Z d W eThe e in this example includes, but is not limited to, 0.001, 0.002, 0.003, 0.004, 0.005, 0.007, 0.009, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.14, 0.2, 0.21, 0.3, 0.32, 0.5, 0.54, 0.7, 0.9, 1, 1.3, 1.5, 1.8, 2, 2.2, 2.5, 2 .8, 3, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.43, 3.45, 3.46, 3.5, 3.55, 3.6, 3.61, 3.64, 3.65, 3.7, 3.75, 3.78, 3.79, 3.8, 3.85, 3.9, 3.95, any one of the point values ​​or the range value between any two of them; preferably 0.04 to 3.7.

[0052] Preferably, 0.25≤a≤1.

[0053] Preferably, c≥d. More preferably, c>d.

[0054] Preferably, d≥e; more preferably, d>e.

[0055] Preferably, d: (c+d+e) = 0.001 to 0.5.

[0056] In some specific embodiments of the present invention, the value of d: (c + d + e) ​​includes but is not limited to 0.001, 0.002, 0.003, 0.037, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.037, 0.04, 0.05, 0.058, 0.06, 0.07, 0.08, 0.085, 0.09, 0.1, 0.15, 0.2, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, any one of the point values ​​or any range value between two. More preferably, d: (c + d + e) ​​= 0.002 ~ 0.4.

[0057] Preferably, e:(c+d+e)=0.0001-0.2.

[0058] In some specific embodiments of the present invention, the value of e:(c+d+e) includes, but is not limited to, 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.037, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.037, 0.04, 0.05, 0.058, 0.06, 0.07, 0.08, 0.085, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or a range between any two of them. More preferably, e: (c+d+e) = 0.002 to 0.1.

[0059] Preferably, the melting point of the molten salt electrolyte is 75-350°C, including but not limited to 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, any one of the point values ​​or the range values ​​between any two of them.

[0060] The molten salt electrolyte provided by the present invention has high ionic conductivity, which can reach 5 to 1000 mS / cm at the operating temperature, and is composed of halide salts of alkali metals, alkaline earth metals and / or aluminum metals with abundant raw materials, and has low cost. At the same time, the molten salt electrolyte is not flammable, and the fast-chargeable aluminum-sulfur battery manufactured is highly safe.

[0061] Preferably, the surface loading of sulfur element in the molten salt electrolyte used in the positive electrode material is ≥1.5 mg / cm 2 (including but not limited to 1.5 mg / cm 2 、1.8mg / cm 2 , 2.0mg / cm 2 , 2.2mg / cm 2 , 2.5mg / cm 2 , 2.6mg / cm 2 , 2.8mg / cm 2 、3mg / cm 2 , 5mg / cm 2 , 7mg / cm 2 , 9mg / cm 2 、10mg / cm 2, 12mg / cm 2 、15mg / cm 2 、18mg / cm 2 , 20mg / cm 2 , 23mg / cm 2 , 25mg / cm 2 、30mg / cm 2 , 40mg / cm 2 、50mg / cm 2 An aluminum-sulfur battery having any one of the point values ​​or any range values ​​between the two).

[0062] The molten salt electrolyte provided by the present invention is used for the surface loading of sulfur element in the positive electrode material ≥1.5 mg / cm 2 The aluminum-sulfur battery can improve the energy density and energy efficiency of the aluminum-sulfur battery.

[0063] Preferably, the surface loading of sulfur element in the molten salt electrolyte used in the positive electrode material is 1.5-4.0 mg / cm 2 Aluminum-sulfur battery.

[0064] The present invention also provides a method for preparing the molten salt electrolyte as described above, comprising the following steps:

[0065] Aluminum halide and at least one halide containing element A are mixed and heated to obtain the molten salt electrolyte; wherein the aluminum halide and the halide containing element A include at least two different halogen elements.

[0066] The preparation method has the advantages of easy operation, simple process, low cost and suitability for mass production.

[0067] In some specific embodiments of the present invention, the aluminum halide includes at least one of aluminum fluoride, aluminum chloride, aluminum bromide and aluminum iodide.

[0068] In some specific embodiments of the present invention, the halide containing element A refers to a compound containing element A and a halogen element, preferably including at least one of A fluoride, A chloride, A bromide and A iodide. Wherein, A is selected from at least one of Ca, Mg, Li, Na, K, Rb and Cs. Preferably, in the process of mixing and heating the aluminum halide and at least one halide containing element A, two, three or four halides containing element A can also be selected.

[0069] In some specific embodiments of the present invention, the method for preparing the molten salt electrolyte comprises: mixing and heating aluminum halide and at least two halides containing element A to obtain the molten salt electrolyte; wherein the halide containing element A includes at least two different halogen elements. Preferably, aluminum halide and at least three halides containing element A are mixed and heated to obtain the molten salt electrolyte.

[0070] Preferably, the heating temperature is 120-500°C, including but not limited to any one of 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 230°C, 250°C, 280°C, 300°C, 330°C, 350°C, 380°C, 400°C, 430°C, 450°C, and 480°C or the range between any two of them.

[0071] In some specific embodiments of the present invention, the heating time is ≥1h, including but not limited to any one of 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 32h, 35h, 38h, 40h, 45h, 50h, 55h, 60h or a range between any two of them; preferably 2-30h.

[0072] In some specific embodiments of the present invention, after the heating is completed, the step of cooling and / or grinding into powder is also included.

[0073] The present invention also provides a fast-chargeable aluminum-sulfur battery, comprising a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and the molten salt electrolyte as described above.

[0074] The molten salt electrolyte is liquid and wets the positive electrode, the separator and the negative electrode.

[0075] The fast-chargeable aluminum-sulfur battery uses a specific molten salt electrolyte to accelerate the electrochemical reaction kinetics, thereby achieving the high capacity and fast-charging performance of the fast-chargeable aluminum-sulfur battery.

[0076] Specifically, the fast-chargeable aluminum-sulfur battery has a high voltage (0.9-1.05V), small battery polarization, and can achieve 10C fast charging performance.

[0077] Preferably, the operating temperature of the fast-chargeable aluminum-sulfur battery is 110-400°C, including but not limited to 105°C, 110°C, 115°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 295°C, 300°C, 320°C, 350°C, 380°C, 390°C, any one of the point values ​​or the range values ​​between any two of them.

[0078] The fast-chargeable aluminum-sulfur battery provided by the present invention has a low operating temperature due to the use of a molten salt electrolyte based on a polyhalogen anion. On the one hand, the operating temperature of the fast-chargeable aluminum-sulfur battery is much lower than the operating temperature of traditional sodium-sulfur batteries and liquid metal batteries (>400°C), reducing the problems of battery packaging corrosion and high thermal management energy consumption. On the other hand, since the operating temperature of the fast-chargeable aluminum-sulfur battery is higher than normal temperature, the battery's own Joule heat can be used to maintain the temperature, thereby simplifying the cooling system required for lithium-ion batteries, so the thermal management manufacturing cost is low and the energy consumption is low.

[0079] In some specific embodiments of the present invention, the structure of the fast-chargeable aluminum-sulfur battery includes a single-layer laminate type. The single-layer laminate battery is a battery comprising a positive electrode layer, a separator electrolyte layer and a negative electrode layer and composed of these three laminates.

[0080] Preferably, the positive electrode comprises a sulfur-containing material and a conductive material.

[0081] Preferably, the sulfur-containing material includes at least one of elemental sulfur, sulfurized polyacrylonitrile, sulfur-selenium compounds and aluminum-sulfur compounds.

[0082] In some specific embodiments of the present invention, the sulfur-selenium compound includes SeS2.

[0083] In some specific embodiments of the present invention, the sulfurized polyacrylonitrile (SPAN) is obtained by polymerizing sulfur and polyacrylonitrile at 400° C. under vacuum conditions.

[0084] Preferably, the conductive material includes at least one of graphene, reduced graphene oxide, carbon nanotubes, carbon fiber materials, porous carbon materials, carbon black, activated carbon and conductive high molecular polymers.

[0085] More preferably, the conductive material includes at least one of reduced graphene oxide, carbon nanotubes, carbon fiber materials, porous carbon materials, activated carbon and conductive high molecular polymers.

[0086] In some specific embodiments of the present invention, the carbon fiber material includes at least one of carbon nanofiber, carbon fiber felt, and carbon cloth. Among them, carbon fiber felt is a felt made of carbon fiber. Carbon cloth, which is the abbreviation of carbon fiber cloth, is made by carbonizing pre-oxidized polymer fiber fabric or weaving carbon fiber. Preferably, the carbon nanofiber includes but is not limited to carbon nanofiber membrane.

[0087] In some specific embodiments of the present invention, the carbon nanotubes include carbon nanotube films.

[0088] In some specific embodiments of the present invention, the porous carbon material includes at least one of macroporous carbon, mesoporous carbon and microporous carbon. Among them, macroporous carbon refers to a porous carbon material containing at least pores of >50nm, mesoporous carbon refers to a porous carbon material containing at least pores of 2-50nm, and microporous carbon refers to a porous carbon material containing pores of <2nm.

[0089] In some specific embodiments of the present invention, the activated carbon is a carbon material with ultra-high specific surface area and narrow pore size distribution obtained by physical or chemical activation, and the activated carbon includes but is not limited to at least one of XFP01 (Jiangsu Xianfeng Nano) and XFP11 (Jiangsu Xianfeng Nano). Preferably, the surface area of ​​the activated carbon is 60 to 4000 m 2 / g.

[0090] In some specific embodiments of the present invention, the conductive high molecular polymer includes but is not limited to at least one of polyaniline, polypyrrole, polythiophene, poly(p-phenylene vinylene) and derivatives thereof.

[0091] In some specific embodiments of the present invention, the positive electrode further includes at least one of a binder, a conductive agent and a current collector.

[0092] In some specific embodiments of the present invention, the preparation method of the positive electrode (positive electrode sheet) comprises the following steps: mixing the sulfur-containing material and the conductive material to obtain a composite material; then mixing the composite material with a conductive agent and a binder to obtain a slurry, and coating it on the surface of the current collector, drying and rolling to obtain the positive electrode. Optionally, after mixing the sulfur-containing material and the conductive material, a heating step is also included. Preferably, the heating temperature is 100 to 600°C, including but not limited to any point value of 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 580°C or any range value between two of them. Preferably, the heating is carried out under vacuum or non-vacuum conditions.

[0093] Preferably, the mass ratio of the conductive material to the sulfur-containing material is 2:1-9, including but not limited to any point value of 2:2, 2:3, 2:4, 2:5, 2:6, 2:7, 2:8, 2:9 or a range value between any two thereof; more preferably, it is 2:2-8.

[0094] Preferably, the thickness of the positive electrode is 20 to 500 μm, including but not limited to 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 45 μm, 50 μm, 60 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 320 μm, 350 μm, 380 μm, 400 μm, 430 μm, 450 μm, and 480 μm, any one of which or a range between any two thereof, more preferably 20 to 50 μm.

[0095] The method for preparing the positive electrode provided by the present invention can prepare a positive electrode with good particle connectivity and high specific capacity. Therefore, the overall energy density of the fast-chargeable aluminum-sulfur battery is much higher than that of the aluminum-sulfur battery in the prior art.

[0096] Preferably, the surface loading of sulfur in the positive electrode of the fast-chargeable aluminum-sulfur battery is ≥1.5 mg / cm 2 , including but not limited to 1.5 mg / cm 2 、1.8mg / cm 2 , 2.0mg / cm 2 , 2.2mg / cm 2 , 2.5mg / cm 2 , 2.6mg / cm 2 , 2.8mg / cm 2 、3mg / cm 2 , 5mg / cm 2 , 7mg / cm 2 , 9mg / cm 2 、10mg / cm 2 , 12mg / cm 2 、15mg / cm 2 、18mg / cm 2 , 20mg / cm 2 , 23mg / cm 2 , 25mg / cm 2 、30mg / cm 2 , 40mg / cm 2 、50mg / cm 2 Any point value in or any range of values ​​between them.

[0097] The surface loading of sulfur element in the positive electrode of the fast-chargeable aluminum-sulfur battery is relatively high, thereby being able to improve the energy density and energy efficiency of the fast-chargeable aluminum-sulfur battery.

[0098] Preferably, the surface loading of sulfur in the positive electrode of the fast-chargeable aluminum-sulfur battery is 1.5 to 4.0 mg / cm 2 .

[0099] In some specific embodiments of the present invention, the negative electrode comprises metallic aluminum and / or an aluminum alloy. Preferably, the aluminum alloy is an aluminum alloy containing one or more metal elements having a higher redox potential than metallic aluminum.

[0100] The fast-chargeable aluminum-sulfur battery provided by the present invention is based on the conversion reaction of Al and S. Aluminum and sulfur are low-cost raw materials with extremely abundant reserves on the earth, and there is no need to rely on expensive lithium. Therefore, the manufacturing cost of the fast-chargeable aluminum-sulfur battery is much lower than the manufacturing cost of lithium-ion batteries in the prior art.

[0101] In some specific embodiments of the present invention, the preparation method of the fast-chargeable aluminum-sulfur battery includes the following steps: contacting the positive electrode with the first surface of the diaphragm; and contacting the second surface of the diaphragm with the negative electrode; introducing a molten salt electrolyte, and making the molten salt electrolyte liquid and infiltrating the positive electrode, the diaphragm and the negative electrode to assemble the core components of the fast-chargeable aluminum-sulfur battery; and then packaging the core components of the fast-chargeable aluminum-sulfur battery.

[0102] Preferably, the method for preparing the fast-chargeable aluminum-sulfur battery further includes the following steps: equipping an external thermal management system, wherein the external thermal management system is used to maintain the operating temperature of the fast-chargeable aluminum-sulfur battery.

[0103] Preferably, the positive electrode comprises: a positive electrode prepared by slurry coating.

[0104] The present invention also provides an energy storage device, comprising the fast-chargeable aluminum-sulfur battery as described above.

[0105] The energy storage device not only has high capacity and fast charging performance, but also has the advantages of good safety performance, high energy density, high energy efficiency, and low preparation cost and thermal management cost.

[0106] The present invention also provides the application of the energy storage device as described above in power grid frequency and peak regulation, solar power stations, wind power stations, reserve power sources, smart microgrids, communication base stations and new energy electric vehicles.

[0107] Compared with the prior art, the present invention has the following beneficial effects:

[0108] (1) The molten salt electrolyte provided by the present invention, by introducing a variety of halogens, on the one hand, the disorder of the aluminum-halogen bonding system of the molten salt electrolyte increases, and the increase in system entropy leads to a larger change in the Gibbs free energy of the bond breaking reaction of the aluminum-halogen bridging bond (that is, ΔG is more negative), and it is easier to break the bond thermodynamically. On the other hand, due to the mixed coordination of aluminum atoms with different halogens, the synergistic effect of multiple halogens greatly increases the asymmetry of the active ion / molecular group, resulting in an asymmetric distribution of the electron cloud density of the aluminum-halogen bond. Therefore, relative to the symmetrical ion / molecular group of a single halogen, the bond breaking barrier of the aluminum-halogen bridging bond is lower. The aluminum-halogen bond is more easily broken under electric field drive, and the desolvation ability of the aluminum ion is stronger, achieving rapid reaction kinetics, thereby achieving high capacity and fast charging performance of the aluminum-sulfur battery.

[0109] (2) The molten salt electrolyte provided by the present invention has a low melting point, high ionic conductivity, is non-flammable, and is highly safe.

[0110] (3) The fast-chargeable aluminum-sulfur battery provided by the present invention has a high voltage, small battery polarization, and can achieve a 10C fast-charging performance.

[0111] (4) The sulfur in the positive electrode of the fast-chargeable aluminum-sulfur battery provided by the present invention has a high specific capacity, thereby effectively improving the energy density.

[0112] (5) The fast-chargeable aluminum-sulfur battery provided by the present invention has a low operating temperature, which can not only reduce the problems of battery packaging corrosion and high thermal management energy consumption, but also reduce thermal management costs.

[0113] (6) The fast-chargeable aluminum-sulfur battery provided by the present invention is based on the conversion reaction of Al and S. Aluminum and sulfur are low-cost raw materials with extremely abundant reserves on the earth. Therefore, the manufacturing cost of the fast-chargeable aluminum-sulfur battery is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0115] Figure 1 A schematic diagram of electrochemically active molecules and polyanion groups contained in the polyhalogen molten salt electrolyte and the monohalogen electrolyte provided by the present invention;

[0116] Figure 2 This is a graph showing the constant current charge and discharge test results of the single-layer laminated fast-chargeable aluminum-sulfur battery provided in Example 1 of the present invention;

[0117] Figure 3 A graph showing the constant current charge and discharge test results of a single-layer laminated fast-chargeable aluminum-sulfur battery provided in Example 2 of the present invention;

[0118] Figure 4 This is a graph showing the constant current charge and discharge test results of a single-layer laminated fast-chargeable aluminum-sulfur battery provided in Example 3 of the present invention;

[0119] Figure 5 A graph showing the constant current charge and discharge test results of a single-layer laminated fast-chargeable aluminum-sulfur battery provided in Example 4 of the present invention;

[0120] Figure 6 A graph showing the constant current charge and discharge test results of a single-layer laminated fast-chargeable aluminum-sulfur battery provided in Example 5 of the present invention;

[0121] Figure 7 This is a graph showing the constant current charge and discharge test results of a single-layer laminated fast-chargeable aluminum-sulfur battery provided in Comparative Example 1 of the present invention;

[0122] Figure 8 This is a graph showing the constant current charge and discharge test results of a single-layer laminated fast-chargeable aluminum-sulfur battery provided in Comparative Example 2 of the present invention;

[0123] Fig. 9 This is a graph showing the constant current charge and discharge test results of the single-layer laminated fast-chargeable aluminum-sulfur battery provided in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0124] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0125] Figure 1 Schematic diagram of electrochemically active molecules and polyanion groups contained in the polyhalogen molten salt electrolyte and the monohalogen electrolyte provided by the present invention.

[0126] Example 1

[0127] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, NaCl and KBr are weighed respectively according to the molar ratio of 61:26:13, added into a container and sealed, transferred to an oven, and kept warm at 140°C for 24 hours to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0128] The general formula of the molten salt electrolyte is Na 0.43 K 0.21 AlCl 3.43 Br 0.21 (The approximate result obtained by taking two significant figures (the same applies to the following embodiments) is: a≈0.64, b≈3.64, c≈3.43, d≈0.21, d: (c+d)≈0.058). The melting point of the molten salt electrolyte is about 102°C.

[0129] This embodiment also provides a positive electrode that can be used for a fast-charged aluminum-sulfur battery, and its preparation method includes the following steps: after mixing XFP01 activated carbon (Jiangsu Xianfeng Nano) and sulfur in a mass ratio of 2:3, heating in an oven at 150°C to obtain a composite material; then using a slurry coating preparation method, the above composite material, Super P carbon black conductive agent and polytetrafluoroethylene binder are mixed in a mass ratio of 8:1:1, using isopropanol as a solvent to prepare a slurry, coating it on the surface of the current collector, and drying it in an oven at 90°C to obtain a positive electrode. Among them, the thickness of the positive electrode is 26μm, and the surface loading of sulfur in the positive electrode is 1.5mg / cm 2 .

[0130] Example 2

[0131] The preparation method of the molten salt electrolyte provided in this embodiment is exactly the same as that in Example 1.

[0132] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 2.5 mg / cm 2 .

[0133] Example 3

[0134] The preparation method of the molten salt electrolyte provided in this embodiment is exactly the same as that in Example 1.

[0135] The preparation method of the positive electrode for fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the composite material is prepared by mixing XFP01 activated carbon (Jiangsu Xianfeng Nano) and sulfur in a mass ratio of 2:6 and heating them in a vacuum environment at 450°C for 12 hours, and the surface loading of sulfur in the positive electrode is 3.2 mg / cm 2 .

[0136] Example 4

[0137] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: in an argon glove box, AlCl3, AlBr3, NaCl and KCl are weighed respectively according to the molar ratio of 50:11:26:13, added into a container and sealed, transferred to an oven, kept warm at 140°C for 24 hours to completely liquefy the components and mix them evenly, and ground into powder after cooling to obtain a molten salt electrolyte.

[0138] The general formula of the molten salt electrolyte is Na 0.43 K 0.21 AlCl 3.1 Br 0.54 (a≈0.43, b≈3.64, c≈3.1, d≈0.54, d:(c+d)≈0.148). The melting point of the molten salt electrolyte is about 100°C.

[0139] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 3.1 mg / cm 2 .

[0140] Example 5

[0141] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, NaCl, KBr, and LiCl are weighed respectively according to the molar ratio of 56:18:8:18, added into a container and sealed, transferred to an oven, and kept warm at 150°C for 24 hours to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0142] The general formula of the molten salt electrolyte is Na 0.32 K 0.14 Li 0.32 AlCl 3.64 Br 0.14 (a≈0.78, b≈3.78, c≈3.64, d≈0.14, d:(c+d)≈0.037). The melting point of the molten salt electrolyte is about 78°C.

[0143] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 3.0 mg / cm 2 .

[0144] Example 6

[0145] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, NaCl, KCl, and LiBr are weighed respectively according to the molar ratio of 56:18:8:18, added into a container and sealed, transferred to an oven, and kept warm at 180°C for 12 hours to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0146] The general formula of the molten salt electrolyte is Na 0.32 K 0.14 Li 0.32 AlCl 3.46 Br 0.32 (a≈0.78, b≈3.78, c≈3.46, d≈0.32, d:(c+d)≈0.085). The melting point of the molten salt electrolyte is about 76°C.

[0147] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 3.1 mg / cm 2 .

[0148] Example 7

[0149] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, NaCl, KBr, LiCl, and KI are weighed respectively according to the molar ratio of 56:18:8:16:2, added into a container and sealed, transferred to an oven, kept warm at 120°C for 12h to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0150] The general formula of the molten salt electrolyte is Na 0.32 K 0.18 Li 0.29 AlCl 3.61 Br 0.14 I 0.04 (a≈0.79, b≈3.79, c≈3.61, d≈0.14, e≈0.04, d:(c+d+e)≈0.037, e:(c+d+e)≈0.01)). The melting point of the molten salt electrolyte is about 78°C.

[0151] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 3.4 mg / cm 2 .

[0152] Example 8

[0153] The preparation method of the molten salt electrolyte provided in this embodiment is exactly the same as that in Example 5.

[0154] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment includes the following steps: after mixing and grinding XFP01 activated carbon (Jiangsu Xianfeng Nano) and SeS2 in a mass ratio of 2:8, heating at 150°C to obtain a composite material; then using a slurry coating preparation method, the above composite material, Super P carbon black conductive agent and polytetrafluoroethylene binder are mixed in a mass ratio of 8:1:1, using isopropanol as a solvent to prepare a slurry, coating it on the surface of the current collector, and drying it in an oven at 90°C to obtain a positive electrode. Among them, the thickness of the positive electrode is 29μm, and the surface loading of sulfur in the positive electrode is 1.8mg / cm 2 .

[0155] Example 9

[0156] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, NaCl, KCl, and LiBr are weighed respectively according to the molar ratio of 56:31:12:1, added into a container and sealed, transferred to an oven, and kept warm at 250°C for 12 hours to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0157] The general formula of the molten salt electrolyte is Na 0.55 K 0.21 Li 0.02 AlCl 3.77 Br 0.018 (a≈0.78, b≈3.788, c≈3.77, d≈0.018, d:(c+d)≈0.0047). The melting point of the molten salt electrolyte is about 86°C.

[0158] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 2.4 mg / cm 2 .

[0159] Example 10

[0160] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, AlBr3, NaCl, KCl, and LiBr are weighed respectively according to the molar ratio of 31:20:36:10:3, added into a container and sealed, transferred to an oven, and kept warm at 250°C for 12 hours to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0161] The general formula of the molten salt electrolyte is Na0.7 K 0.20 Li 0.06 AlCl 2.73 Br 1.24 (a≈0.96, b≈3.96, c≈2.73, d≈1.24, d:(c+d)≈0.31). The melting point of the molten salt electrolyte is about 142°C.

[0162] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 2.1 mg / cm 2 .

[0163] Embodiment 11

[0164] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, NaCl, KBr, LiCl, and KI are weighed respectively according to the molar ratio of 50:37:6:6:1, added into a container and sealed, transferred to an oven, and kept warm at 250°C for 12 hours to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0165] The general formula of the molten salt electrolyte is Na 0.74 K 0.14 Li 0.12 AlCl 3.86 Br 0.12 I 0.018 (a=1, b=4, c≈3.86, d≈0.12, e≈0.018, d: (c+d+e)≈0.03, e: (c+d+e)≈0.0045). The melting point of the molten salt electrolyte is about 177°C.

[0166] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 3.4 mg / cm 2 .

[0167] Example 12

[0168] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, NaCl, KBr, LiCl, and KI are weighed respectively according to the molar ratio of 56:31:1:11:1, added into a container and sealed, transferred to an oven, and kept warm at 250°C for 12 hours to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0169] The general formula of the molten salt electrolyte is Na 0.55 K0.036 Li 0.20 AlCl 3.75 Br 0.018 I 0.018 (a≈0.786, b≈3.786, c≈3.75, d≈0.018, e≈0.018, d:(c+d+e)≈0.0048, e:(c+d+e)≈0.0048). The melting point of the molten salt electrolyte is about 90°C.

[0170] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment is basically the same as that in Example 1, except that the surface loading of sulfur element in the positive electrode is 4.0 mg / cm 2 .

[0171] Example 13

[0172] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, CaBr2 and KI are weighed respectively according to the molar ratio of 80:10:10, added into a container and sealed, transferred to an oven, and kept warm at 250°C for 30 hours to mix the components evenly and completely liquefy, and then ground into powder after cooling to obtain a molten salt electrolyte.

[0173] The general formula of the molten salt electrolyte is Ca 0.125 K 0.125 AlCl3Br 0.25 I 0.125 (a=0.25, b=3.375, c=3, d=0.25, e=0.125, d: (c+d+e)≈0.074, e: (c+d+e)≈0.037). The melting point of the molten salt electrolyte is about 150°C.

[0174] The preparation method of the positive electrode for the fast-chargeable aluminum-sulfur battery provided in this embodiment includes the following steps: under the protection of inert gas, carbon nanotubes and Al2S3 are mixed in a mass ratio of 2:2 to obtain a composite material; then, the composite material, Super P carbon black conductive agent and polytetrafluoroethylene binder are mixed in a mass ratio of 8:1:1 by a slurry coating preparation method, isopropanol is used as a solvent to prepare a slurry, which is coated on the surface of the current collector and dried in an oven at 90°C to obtain a positive electrode. Among them, the thickness of the positive electrode is 41μm, and the surface loading of sulfur in the positive electrode is 2.0mg / cm 2 .

[0175] Embodiment 14

[0176] The preparation method of the molten salt electrolyte provided in this embodiment includes the following steps: under the protection of inert gas, AlCl3, MgCl2, NaBr and KI are weighed respectively according to the molar ratio of 60:10:10:5, added into a container and sealed, transferred to an oven, kept warm at 250°C for 20h to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0177] The general formula of the molten salt electrolyte is Mg 0.17 Na 0.17 K 0.08 AlCl 3.33 Br 0.17 I 0.08 (a≈0.42, b≈3.58, c≈3.33, d≈0.17, e≈0.08, d:(c+d+e)≈0.047, e:(c+d+e)≈0.022). The melting point of the molten salt electrolyte is about 165°C.

[0178] The preparation method of the positive electrode that can be used for the fast-charged aluminum-sulfur battery provided in this embodiment includes the following steps: mixing sulfur and polyacrylonitrile in a mass ratio of 3:1, heat treating at 400°C under vacuum conditions for 10 hours, and obtaining a sulfurized polyacrylonitrile composite material with a sulfur content of 45wt%. Through the preparation method of slurry coating, the sulfurized polyacrylonitrile composite material, Super P carbon black conductive agent and polytetrafluoroethylene binder are mixed in a mass ratio of 8:1:1, and isopropanol is used as a solvent to prepare a slurry, which is coated on the surface of the current collector and dried in an oven at 90°C to obtain a positive electrode. Among them, the thickness of the positive electrode is 35μm, and the surface loading of sulfur in the positive electrode is 2.6mg / cm 2 .

[0179] Embodiment 15

[0180] This embodiment provides a single-layer laminated fast-chargeable aluminum-sulfur battery, and a preparation method thereof includes the following steps:

[0181] The battery is a Swagelok-type sealed structure, and the pole piece and diaphragm have a diameter of 10 mm. The diaphragm, positive electrode and negative electrode are cut according to the battery model design. Under the protection of inert gas, the positive electrode is contacted with the first surface of the diaphragm; and the second surface of the diaphragm is contacted with the negative electrode; then a molten salt electrolyte is introduced, and the molten salt electrolyte is contacted with the positive electrode, the diaphragm and the negative electrode to assemble the core components of the fast-chargeable aluminum-sulfur battery; and then the core components of the fast-chargeable aluminum-sulfur battery are encapsulated in a Swagelok-type sealed structure battery to obtain a single-layer laminated fast-chargeable aluminum-sulfur battery. The single-layer laminated fast-chargeable aluminum-sulfur battery is placed in an oven within a preset temperature range and left to stand for 2 hours, and the current collectors of the single-layer laminated fast-chargeable aluminum-sulfur battery are respectively connected to a battery tester to complete a constant current charge and discharge test.

[0182] In the present invention, the current density of 1C represents 1675mA / g, and the mass in the two units of mA / g and mAh / g is based on the sulfur element in the positive electrode, that is, 1mA / g means 1mA per gram of sulfur, and 1mAh / g means 1mAh per gram of sulfur. In the battery constant current charge and discharge test, the discharge cut-off voltage is 0.5V; the charge cut-off voltage is 1.5V at the charge rate of 1C and 2C, and the charge cut-off voltage is 1.6V at the charge rate of 5C and 10C.

[0183] Comparative Example 1

[0184] The preparation method of the molten salt electrolyte provided in this comparative example comprises the following steps: under the protection of inert gas, AlCl3, NaCl and KCl are weighed respectively according to the molar ratio of 61:26:13, added into a container and sealed, transferred into an oven, kept warm at 140°C for 24h to mix the components evenly and completely liquefy, and ground into powder after cooling to obtain a molten salt electrolyte.

[0185] The general formula of the molten salt electrolyte is Na 0.43 K 0.21 AlCl 3.64 (a=0.64, b=3.64, c=0) The melting point of the molten salt electrolyte is 100°C.

[0186] The preparation method of the positive electrode provided in this comparative example is basically the same as that of Example 1, except that the surface loading of sulfur element in the positive electrode is 1.5 mg / cm 2 .

[0187] Comparative Example 2

[0188] The preparation method of the molten salt electrolyte provided in this comparative example is exactly the same as that of comparative example 1.

[0189] The preparation method of the positive electrode provided in this comparative example is basically the same as that of Example 2, except that the surface loading of sulfur element in the positive electrode is 2.3 mg / cm 2 .

[0190] Comparative Example 3

[0191] The preparation method of the molten salt electrolyte provided in this comparative example is exactly the same as that of comparative example 1.

[0192] The preparation method of the positive electrode provided in this comparative example is basically the same as that of Example 3, except that the surface loading of sulfur element in the positive electrode is 3.1 mg / cm 2 .

[0193] Comparative Example 4

[0194] The preparation method of the molten salt electrolyte provided in this comparative example is basically the same as that of Example 1, except that the molar ratio of AlCl3, NaCl and KBr is replaced with 60:31:31.

[0195] The general formula of the molten salt electrolyte is Na 0.52 K 0.52 AlCl 3.52 Br 0.52 (a=1.04, b=4.04, c≈3.52, d≈0.52, d: (c+d)≈0.13) The melting point of the molten salt electrolyte is 220°C.

[0196] The preparation method of the positive electrode provided in this comparative example is basically the same as that of Example 1, except that the surface loading of sulfur element in the positive electrode is 3.0 mg / cm 2 .

[0197] Experimental Example 1

[0198] The molten salt electrolyte prepared in Example 1 and the positive electrode prepared in Example 1 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 1. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 1 was subjected to constant current charge and discharge tests (test temperature was 115° C.), and the results were as follows: Figure 2 As shown. Figure 2 It can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery in Example 1 has an initial discharge capacity of 1108 mAh / g at a charging current density of 1 C and a discharge current density of 0.2 C. After 60 cycles, it still has 908.5 mAh / g, and the capacity retention rate relative to the fifth cycle is 89.1%.

[0199] The molten salt electrolyte prepared in Example 2 and the positive electrode prepared in Example 2 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 2. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 2 was subjected to constant current charge and discharge tests (test temperature was 115° C.), and the results were as follows: Figure 3 As shown. Figure 3 It can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery in Example 2 has an average specific capacity of approximately 886.9 mAh / g, 768.4 mAh / g, 709.1 mAh / g, 687.5 mAh / g and 410 mAh / g at a fixed discharge current density of 0.5 C and charging current densities of 0.5 C, 1 C, 2 C, 5 C and 10 C, respectively, showing excellent rate performance.

[0200] The molten salt electrolyte prepared in Example 3 and the positive electrode prepared in Example 3 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 3. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 3 was subjected to constant current charge and discharge tests (test temperature was 115° C.), and the results are as follows: Figure 4 As shown. Figure 4 It can be seen that the discharge specific capacity of the single-layer laminated fast-chargeable aluminum-sulfur battery in Example 3 at a current density of 0.2C in the first three cycles is 1132 mAh / g, 830 mAh / g and 810 mAh / g, respectively, and the overpotential of charge and discharge is about 0.24 V. The overpotential of charge and discharge is defined as half of the difference between the average voltage of charge and discharge, and the same applies to the following description.

[0201] The molten salt electrolyte prepared in Example 4 and the positive electrode prepared in Example 4 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 4. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 4 was subjected to constant current charge and discharge tests (test temperature was 115° C.), and the results are as follows: Figure 5 As shown. Figure 5 It can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 4 has a specific capacity of 320.7 mAh / g after 100 cycles at a discharge current density of 0.5 C and a charging current density of 10 C.

[0202] The molten salt electrolyte prepared in Example 5 and the positive electrode prepared in Example 5 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 5. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 5 was subjected to constant current charge and discharge tests (test temperature was 110° C.), and the results are as follows: Figure 6 As shown. Figure 6 It can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 5 has an initial discharge capacity of 1088 mAh / g at a charging current density of 1 C and a discharge current density of 0.2 C, and still has 736 mAh / g after 130 cycles.

[0203] The molten salt electrolyte prepared in Example 6 and the positive electrode prepared in Example 6, the diaphragm is a glass fiber diaphragm, the negative electrode is an aluminum alloy foil (2024 aluminum alloy, 150 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 is used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 6. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 6 was subjected to a constant current charge and discharge test (test temperature was 110° C.), and it was found that at a charging current density of 1C and a discharge current density of 0.2C, the first discharge capacity was 1063 mAh / g, and after 50 cycles, it still had 819 mAh / g.

[0204] The molten salt electrolyte prepared in Example 7 and the positive electrode prepared in Example 7, the glass fiber separator, the aluminum foil (100 μm thick) for the negative electrode, and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 were used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 7. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 7 was subjected to a constant current charge and discharge test (test temperature was 110° C.), and it was found that at a charging current density of 1C and a discharge current density of 0.2C, the first discharge capacity was 1188 mAh / g, and after 50 cycles, it was still 894 mAh / g.

[0205] The molten salt electrolyte prepared in Example 8 and the positive electrode prepared in Example 8, the diaphragm is a glass fiber diaphragm, the negative electrode is an aluminum alloy foil (2024 aluminum alloy, 150 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 is used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 8. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 8 was subjected to a constant current charge and discharge test (test temperature was 110° C.), and it was found that at a charging current density of 1C and a discharge current density of 0.2C, the first discharge capacity was 784 mAh / g, and after 50 cycles, it still had 693 mAh / g.

[0206] The molten salt electrolyte prepared in Example 9 and the positive electrode prepared in Example 9, the glass fiber separator, the aluminum foil (100 μm thick) for the negative electrode, and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 were used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 9. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 9 was subjected to a constant current charge and discharge test (test temperature was 110° C.), and it was found that the first discharge capacity was 1138 mAh / g at a charging current density of 1C and a discharge current density of 0.2C, and there was still 864 mAh / g after 50 cycles.

[0207] The molten salt electrolyte and the positive electrode prepared in Example 10 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 10. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 10 was subjected to a constant current charge and discharge test (test temperature was 180° C.), and it was found that at a charging current density of 1C and a discharge current density of 0.2C, the first discharge capacity was 1020 mAh / g, and after 50 cycles, it still had 802 mAh / g.

[0208] The molten salt electrolyte prepared in Example 11 and the positive electrode prepared in Example 11, the glass fiber separator, the aluminum foil (100 μm thick) for the negative electrode, and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 were used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 11. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 11 was subjected to a constant current charge and discharge test (test temperature was 250° C.), and it was found that at a charging current density of 1C and a discharge current density of 0.2C, the first discharge capacity was 980 mAh / g, and after 50 cycles, it was still 764 mAh / g.

[0209] The molten salt electrolyte prepared in Example 12 and the positive electrode prepared in Example 12, the glass fiber separator, the aluminum foil (100 μm thick) for the negative electrode, and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 were used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 12. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 12 was subjected to a constant current charge and discharge test (test temperature was 110° C.), and it was found that the first discharge capacity was 820 mAh / g at a charging current density of 1 C and a discharge current density of 0.2 C, and there was still 613 mAh / g after 50 cycles.

[0210] The molten salt electrolyte prepared in Example 13 and the positive electrode prepared in Example 13, the glass fiber separator, the aluminum foil (100 μm thick) for the negative electrode, and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 were used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 13. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 13 was subjected to a constant current charge and discharge test (test temperature was 180° C.), and it was found that the first discharge capacity was 970 mAh / g at a charging current density of 1 C and a discharge current density of 0.2 C, and there was still 821 mAh / g after 50 cycles.

[0211] The molten salt electrolyte prepared in Example 14 and the positive electrode prepared in Example 14, the glass fiber separator, the aluminum alloy foil (2024 aluminum alloy, 150 μm thick) and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 were used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 14. The single-layer laminated fast-chargeable aluminum-sulfur battery of Example 14 was subjected to constant current charge and discharge tests (test temperature was 250° C.), and it was found that the first discharge capacity was 1150 mAh / g at a charging current density of 1 C and a discharge current density of 0.2 C, and there was still 856 mAh / g after 50 cycles.

[0212] The molten salt electrolyte and the positive electrode prepared in Comparative Example 1 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 1. The single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 1 was subjected to constant current charge and discharge tests (test temperature was 115° C.), and the results are as follows: Figure 7 As shown. Figure 7 It can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery in comparative example 1 has an initial discharge capacity of 1051 mAh / g at a current density of 0.2C for both charging and discharging currents, and a capacity of 936 mAh / g after four cycles. Subsequently, at a charging current density of 1C and a discharge current density of 0.2C, after 60 cycles, the capacity is only 526 mAh / g, and the capacity retention rate relative to the fifth cycle is 78.9%.

[0213] The molten salt electrolyte prepared in Comparative Example 2 and the positive electrode prepared in Comparative Example 2 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 2. The single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 2 was subjected to constant current charge and discharge tests (test temperature was 115°C), and the results are as follows: Figure 8 As shown. Figure 8It can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery in Comparative Example 2 has an average specific capacity of 692.3 mAh / g, 614.5 mAh / g, 313.1 mAh / g, 217.3 mAh / g and 179.3 mAh / g at a fixed discharge current density of 0.5 C and charging current densities of 0.5 C, 1 C, 2 C, 5 C and 10 C, respectively.

[0214] The molten salt electrolyte prepared in Comparative Example 3 and the positive electrode prepared in Comparative Example 3 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 3. The single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 3 was subjected to constant current charge and discharge tests (test temperature was 115°C), and the results are as follows: Fig. 9 As shown. Fig. 9 It can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery in comparative example 3 has a discharge capacity of 879 mAh / g, 672 mAh / g and 636.4 mAh / g in the first three cycles at a current density of 0.2C, and the overpotential of charge and discharge is as high as about 0.4V.

[0215] The molten salt electrolyte prepared in Comparative Example 4 and the positive electrode prepared in Comparative Example 4 were used, the diaphragm was a glass fiber diaphragm, the negative electrode was an aluminum foil (100 μm thick), and the preparation method of the single-layer laminated fast-chargeable aluminum-sulfur battery described in Example 15 was used to prepare the single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 4. The single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 4 was subjected to a constant current charge and discharge test (the test temperature was 230° C.), and the results showed that the single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 4 had a discharge specific capacity of 625 mAh / g, 565 mAh / g and 478 mAh / g in the first three cycles at a current density of 0.2C, and the overpotential of charge and discharge was as high as about 0.4V.

[0216] By comparing the above test results, it can be seen that the single-layer laminated fast-chargeable aluminum-sulfur battery of Example 1 has a specific capacity of 908.5 mAh / g after 60 cycles at a current density of 1C, showing a high reversible capacity and stable cycle performance. However, the single-layer laminated fast-chargeable aluminum-sulfur battery of Comparative Example 1 has a specific capacity of only 526 mAh / g after 60 cycles at a current density of 1C.

[0217] Example 2 Single-layer laminated fast-chargeable aluminum-sulfur battery at a current density of 10C and 2.5 mg / cm 2 At a surface loading of 1.547 W, it has an average specific capacity of about 410 mAh / g, showing excellent fast charging characteristics and good cycle stability. 2At a surface loading of , the specific capacity is only 179.3 mAh / g.

[0218] Example 3 Single-layer laminated fast-chargeable aluminum-sulfur battery with a surface loading of 3.2 mg / cm 2 At a current density of 0.2C, it has a reversible capacity of 815.5 mAh / g and an overpotential of 0.24 V, which are better than the electrochemical performance of the single-layer laminated fast-chargeable aluminum-sulfur battery in comparative example 3 (reversible capacity of 636.4 mAh / g, overpotential of 0.4 V).

[0219] Under similar surface loading and the same test conditions, the fast-chargeable aluminum-sulfur batteries prepared in Examples 1 to 3 have better cycle stability, higher specific capacity, better rate performance and lower overpotential than those in Comparative Examples 1 to 3. This shows that the present invention increases the disorder of the aluminum-halogen bonding system by introducing two halogens, Cl / Br, into the molten salt electrolyte system. The increase in system entropy makes the bond breaking reaction of the aluminum-halogen bridging bond more likely to occur. In addition, aluminum atoms are mixed with different halogens for coordination, and the synergistic effect of multiple halogens greatly increases the asymmetry of the active ion / molecular group, which ultimately leads to a lower bond breaking energy barrier for the aluminum-halogen covalent bond, a stronger desolvation ability of aluminum ions, and a significant improvement in the reaction kinetics of the electrolyte, thereby achieving a high specific capacity, fast charging performance and good cycle stability of the fast-chargeable aluminum-sulfur battery.

[0220] By comparing Example 1 with Example 5 to Example 12, it can be found that the fast-chargeable aluminum-sulfur battery made of the molten salt electrolyte with a specific composition provided by the present invention can exhibit high reversible capacity and good cycle stability at a charging current density of 1C. Among them, Example 7, Example 11, and Example 12 use a molten salt electrolyte containing three halogens, in which the three halogen elements Cl / Br / I are all bonded to aluminum atoms, which can further increase the disorder of the aluminum-halogen bond in the Al2X6 and polyanion groups, and make the electron cloud distribution more uneven, thereby further reducing the bond breaking energy barrier of the aluminum-halogen covalent bond, significantly improving the desolvation ability of the electrolyte, and further improving the reaction kinetics of the aluminum-sulfur battery.

[0221] It can be found from Example 8, Example 13 and Example 14 that the molten salt electrolyte provided by the present invention can be extended to SeS2, Al2S3 and sulfided polyacrylonitrile positive electrodes, and all exhibit high reversible capacity and good cycle stability, further proving the universal application of the present invention in different sulfur-based positive electrode materials.

[0222] It can be found from Comparative Example 4 that the molten salt electrolyte provided by the present invention is a AlX bWhen a>1 and b>4 in the general formula, the reversible capacity of the fast-chargeable aluminum-sulfur battery decreases and the battery polarization increases, which proves that the molten salt electrolyte has a a AlX b The necessity of 0.1≤a≤1, 3.1≤b≤4 in the general formula.

[0223] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A molten salt electrolyte, characterized in that: The molten salt electrolyte is used for aluminum-sulfur batteries, and the molten salt electrolyte includes a general formula A a AlCl c Z d The molten salt and / or the general formula A a AlCl c Z d W e of molten salt; Formula A a AlCl c Z d A is selected from at least two of Ca, Mg, Li, Na, and K; Z is selected from one of F, Br, and I; 0.1≤a<1, 0.001≤c≤4, 0.001≤d≤4; c≥d, and d: (c+d)=0.001~0.5; Formula A a AlCl c Z d W e wherein A is selected from at least two of Ca, Mg, Li, Na, and K; Z and W are each independently selected from one of F, Br, and I, and Z and W are two different halogen elements; 0.1≤a<1, 0.001≤c≤4, 0.001≤d≤4, 0.0001≤e≤4, and c≥d.

2. The molten salt electrolyte according to claim 1, characterized in that Formula A a AlCl c Z d , 0.25≤a<1.

3. The molten salt electrolyte according to claim 1, characterized in that Formula A a AlCl c Z d W e , 0.25≤a<1.

4. The molten salt electrolyte according to claim 3, characterized in that Formula A a AlCl c Z d W e , d ≥ e.

5. The molten salt electrolyte according to claim 3, characterized in that Formula A a AlCl c Z d W e In, d: (c+d+e)=0.001~0.5; And / or, e: (c+d+e)=0.0001~0.

2.

6. The molten salt electrolyte according to any one of claims 1 to 5, characterized in that The melting point of the molten salt electrolyte is 75-350°C.

7. The molten salt electrolyte according to any one of claims 1 to 5, characterized in that The surface loading of sulfur element in the positive electrode material of the molten salt electrolyte is ≥1.5 mg / cm 2 Aluminum-sulfur battery.

8. The molten salt electrolyte according to any one of claims 1 to 5, characterized in that The surface loading of sulfur element in the molten salt electrolyte used in the positive electrode material is 1.5-4.0 mg / cm 2 Aluminum-sulfur battery.

9. The method for preparing a molten salt electrolyte according to any one of claims 1 to 8, characterized in that: The steps include: Aluminum halide and at least two halides containing element A are mixed and heated to obtain the molten salt electrolyte; wherein the aluminum halide and the halides containing element A include at least two different halogen elements.

10. The method for preparing a molten salt electrolyte according to claim 9, characterized in that: The heating temperature is 120-500°C.

11. A fast-chargeable aluminum-sulfur battery, characterized in that: Comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a molten salt electrolyte according to any one of claims 1 to 8; The molten salt electrolyte is liquid and wets the positive electrode, the separator and the negative electrode.

12. The fast-chargeable aluminum-sulfur battery according to claim 11, characterized in that: The operating temperature of the fast-chargeable aluminum-sulfur battery is 110-400°C.

13. The fast-chargeable aluminum-sulfur battery according to claim 11, characterized in that: The positive electrode includes a sulfur-containing material and a conductive material.

14. The fast-chargeable aluminum-sulfur battery according to claim 13, characterized in that: The sulfur-containing material includes at least one of sulfur element, sulfurized polyacrylonitrile, sulfur-selenium compounds and aluminum-sulfur compounds.

15. The fast-chargeable aluminum-sulfur battery according to claim 13, characterized in that: The conductive material includes at least one of graphene, reduced graphene oxide, carbon nanotubes, carbon fiber materials, porous carbon materials, carbon black, activated carbon and conductive high molecular polymers.

16. The fast-chargeable aluminum-sulfur battery according to claim 11, characterized in that: In the positive electrode of the fast-chargeable aluminum-sulfur battery, the surface loading of sulfur element is ≥1.5 mg / cm 2 .

17. The fast-chargeable aluminum-sulfur battery according to claim 11, characterized in that: The surface loading of sulfur element in the positive electrode of the fast-chargeable aluminum-sulfur battery is 1.5-4.0 mg / cm 2 .

18. An energy storage device, characterized in that Comprising the fast-chargeable aluminum-sulfur battery as described in claim 11.

19. Application of the energy storage device as claimed in claim 18 in power grid frequency and peak regulation, solar power stations, wind power stations, reserve power sources, smart microgrids, communication base stations and new energy electric vehicles.

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