A positive electrode composite material, an electrode, a three-ion secondary battery and its applications

Abstract

This invention specifically relates to a positive electrode composite material, an electrode, a three-ion secondary battery, and their applications. During charging and discharging, the system simultaneously undergoes reversible intercalation and deintercalation of two monovalent ions on the positive electrode side: the extraction or insertion of a monovalent cation and the insertion or extraction of a monovalent anion; on the negative electrode side, an electrochemical deposition or stripping of a polyvalent metal ion occurs. Throughout the process, the total number of non-metallic atoms carried by the cations and anions entering and leaving the positive electrode side is equal; the types and quantities of metal elements decreased (or increased) at the positive electrode during the reaction are exactly the same as the types and quantities of metal elements increased (or decreased) at the negative electrode. The electrolyte composition remains unchanged throughout the cycle and does not participate in the net electrochemical reaction, significantly reducing the amount of electrolyte used in the battery, thereby greatly improving the battery's energy density.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage battery technology, specifically relating to a positive electrode composite material, an electrode, a three-ion secondary battery and its applications. Background Technology

[0002] To date, secondary batteries are generally considered to consist of only two types of battery systems: single-ion and dual-ion. Single-ion secondary batteries rely on a single ion shuttling between the positive and negative electrodes, belonging to a symmetrical battery with positive and negative electrode reactions. The electrolyte, acting as the ion conductor between the positive and negative electrodes, remains unchanged during charging and discharging. Single-ion systems are suitable for monovalent metal ions (such as Li). + Batteries exhibit advantages such as high energy density and rapid kinetics. Multivalent metal diions (such as Mg²⁺) possess these advantages. 2+ Al 3+ Batteries, such as those described in the paper "Efficient Aluminum Chloride" Natural Graphite Battery》(Chem. Mater. 2017, 29, 4484 4492 (hereinafter referred to as "Prior Art 1") solves the kinetic problem of slow diffusion of multivalent metals in the bulk phase of the positive electrode by deintercalating monovalent ions into the positive electrode and depositing / stripping polyvalent metal ions into the negative electrode. However, as described in patent document CN114430061B, both the anions and cations in the electrolyte of a dual-ion battery are active materials, resulting in a large amount of electrolyte used and low battery energy density.

[0003] The paper "Rechargeable Aluminum Organic Batteries" (Kim DJ et al., Nature Energy, hereinafter referred to as "Prior Art 2") studies a hybrid electrode constructed from organic electrode materials PQ triangles (PQ-Δ) and graphite sheets. This scheme improves the specific capacity by addressing the low electronic conductivity and limited areal loading of traditional organic electrodes. It claims to achieve bipolar storage of anions and cations, with a PQ to graphite mass ratio of 1:1. Because the operating potential of PQ is significantly lower than that of graphite, the insertion of anions and the extraction of cations in this system occur in stages at different voltages. In other words, the electrolyte participates in the net electrochemical reaction at each stage, and the electrolyte composition cannot be guaranteed to remain constant. Therefore, it can only be considered a staged dual-ion battery, and the problem of excessive electrolyte usage still exists.

[0004] Furthermore, organic electrode materials are common cathode materials for multivalent metal-ion batteries. To overcome the insufficient conductivity of organic electrode materials, existing technologies typically add a large amount of conductive carbon, such as carbon black, carbon nanotubes, or graphene. Although the addition of conductive carbon can improve electrode conductivity, it often does not act as an active material, thus reducing the energy density of the battery cell. Summary of the Invention

[0005] Therefore, this invention provides a positive electrode composite material, an electrode, a three-ion secondary battery, and their applications to simultaneously solve the problems of slow kinetics and low energy density in multivalent metal ion secondary batteries.

[0006] To this end, the present invention provides the following technical solution.

[0007] The three-ion secondary battery of this invention refers to a system in which, during charging and discharging, reversible intercalation and deintercalation of two monovalent ions simultaneously occur on the positive electrode side: the extraction or insertion of a monovalent cation and the insertion or extraction of a monovalent anion; while on the negative electrode side, electrochemical deposition or stripping of a polyvalent metal ion occurs. Throughout the process, the total number of non-metallic element atoms carried by the cations and anions entering and leaving the positive electrode side is equal; the types and quantities of metal elements decreased (or increased) at the positive electrode during the reaction are exactly the same as the types and quantities of metal elements increased (or decreased) at the negative electrode. The electrolyte composition remains unchanged throughout the cycle and does not participate in the net electrochemical reaction. This battery belongs to a secondary battery system with mutually matched positive and negative electrode reactions and symmetrical mass exchange.

[0008] Three-ion secondary batteries consist of positive electrode material, negative electrode material, and electrolyte.

[0009] Anode materials fall into two main categories: Type X (+2 valence state), which is a metal such as Mg, Zn, or Ca; or Type Y (+3 valence state), which is a metal such as Al, La, Cr, or Fe.

[0010] Electrolytes include one of the following: organic electrolytes, aqueous electrolytes, ionic liquid electrolytes, and solid electrolytes. The cations in the electrolyte contain one of the following metals: Al, Cr, Fe, V, Zn, Mg, and Ca. The specific choice should be consistent with the metal material used in the negative electrode material. The anions contain one of the following: Cl, Br, and I.

[0011] Preferably, the amount of electrolyte used does not exceed 3 g / (Ah).

[0012] The positive electrode material is a composite material comprising material A and material B. Material A is graphite, including one or more of natural graphite and expanded graphite. Material B is an organic electrode material with an operating voltage difference of less than 0.2 V from material A and possessing a carbonyl active group, including one or more of pyrene-4,5,9,10-tetraone (PTO), 2,3,5,6-tetraphthalimide-p-benzoquinone (TPBQ), 9,10-[1,2]benzanthracene-2,3,6,7,14,15(9H,10H)-hexanone (BAHO), and myristo-1,2,5,6,9,10-hexanone (CHO). Organic electrode materials containing carbonyl active groups, such as PQ described in prior art 2, have a significantly lower operating voltage than graphite and are therefore not included in material B of this invention.

[0013] The operating voltage refers to the potential difference between the positive and negative electrodes of the battery during charging and discharging. The standard method for measuring the operating voltage is the constant current charge-discharge method, which involves charging and discharging under a specified constant current, recording the voltage change over time / capacity, and taking the average voltage of the plateau region in the charge-discharge curve as the operating voltage.

[0014] The mass ratio of material A to material B is related to the type of negative electrode material.

[0015] When the negative electrode material is type X, the mass ratio of material A to material B (m) a :m b )satisfy: ;like: , , , , , , .

[0016] When the negative electrode material is of type Y, the mass ratio of material A to material B (m) a :m b )satisfy: ;like: , , , .

[0017] Where C a Let C be the specific capacity of material A. b The specific capacity of material B is given. Both materials A and B are commonly used cathode materials, and their specific capacities are common knowledge. For illustrative purposes, the specific capacities of natural graphite and expanded graphite are 50 mAh / g, while the specific capacities of PTO, TPBQ, BAHO, and CHO are 140 mAh / g, 40 mAh / g, 200 mAh / g, and 230 mAh / g, respectively.

[0018] Preferably, the negative electrode material comprises metallic Al, and the positive electrode material comprises expanded graphite and pyrene-4,5,9,10-tetraketone (PTO), wherein the mass ratio of expanded graphite to PTO (m a :m b )satisfy , i.e. m a :m b =7:5.

[0019] The inventive concept of this invention is described below:

[0020] The inventors discovered that the positive and negative electrode reactions in existing dual-ion batteries are asymmetrical. Taking aluminum / graphite batteries as an example, for instance... Figure 14 As shown, during charging, [AlCl4] forms on the graphite side of the positive electrode. - Anion insertion occurs, while Al2O3 occurs on the negative electrode side. 3+ Cation deposition. Due to the different types of ions reacting on the positive and negative electrode sides, ions in the electrolyte must be continuously consumed during charging, forcing a significant increase in electrolyte usage and a substantial decrease in the overall battery energy density. This makes electrolyte usage a major factor limiting battery energy density. For example, in prior art 1, the electrolyte usage for aluminum / graphite batteries requires at least 20.83 g / (Ah).

[0021] To overcome this problem, the inventors ingeniously designed a positive electrode composite material composed of graphite with a basically consistent operating voltage range and organic electrode materials with carbonyl active groups, and further developed a three-ion secondary battery with mutually matched positive and negative electrode reactions and symmetrical mass exchange. The following description uses the optimal choice of this invention as an example.

[0022] As attached Figure 1 As shown, during charging, PTO in the positive electrode material releases a monovalent cation [AlCl2]. + At the same time, graphite will embed a monovalent anion [AlCl4]. - On the negative electrode side, Al will occur. 3+ The deposition of PTO was achieved by controlling the mass ratio of graphite to PTO. It can achieve monovalent anion [AlCl4]. - The intercalation amount is equal to twice that of the monovalent cation [AlCl2]. + The amount of Cl extracted is thus ensured in the cathode material. - The ion content remains unchanged, but only Al is net removed. 3+ Meanwhile, the reaction occurring on the negative electrode side is exactly an equal amount of Al. 3+ Deposited onto the electrodes. Therefore, the reactions at the positive and negative electrodes are symmetrical, i.e., Al in the electrolyte... 3+ and Cl -The components remain constant throughout the cycle, similar to a reaction catalyst, and do not participate in the net electrochemical reaction, thus significantly reducing the amount of electrolyte used.

[0023] Furthermore, to achieve the objectives of this invention, it is essential to ensure that the cathode material undergoes [AlCl2] extraction. + Time and embedding [AlCl4] - There are often similar operating voltages. The PTO operating voltage used in this invention is very close to that of graphite, both around 1.4 ohms in Al-ion battery systems. The voltage is between 2.2 V, which just meets the requirements. However, if the cathode material cannot guarantee the extraction of [AlCl2]... + Time and embedding [AlCl4] - If a similar operating voltage is present, [AlCl2] will be desorbed. + and embedding [AlCl4] - Conducting the reaction at different voltage stages, similar to prior art 2, it can only be considered a staged dual-ion battery, not a three-ion battery. In other words, the electrolyte participates in the net electrochemical reaction at each stage, and the composition cannot be guaranteed to remain unchanged, thus failing to achieve the goal of significantly reducing the amount of electrolyte used in this invention.

[0024] The beneficial effects of this invention are: by using a symmetrical reaction, the amount of electrolyte used is significantly reduced to no more than 3 g / (Ah), thereby greatly increasing the energy density.

[0025] As a non-optimal option, it is acceptable as long as the amount of monovalent cations extracted is approximately equal to 2 or 3 times the amount of monovalent anions inserted (i.e., This ensures that the content of anions in the positive electrode material remains unchanged, with only a net removal of metal cations. At the same time, the reaction occurring on the negative electrode side results in the deposition of almost an equal amount of metal cations onto the electrode, which can significantly reduce the amount of electrolyte used. Such technical solutions are obviously within the scope of protection of this invention.

[0026] Furthermore, when the negative electrode material is another Y-type metal, such as La, Cr, or Fe, a monovalent cation [YCl2] can also be achieved. + Monovalent anion [YCl4] - Multivalent metal ions Y 3+ The reaction equilibrium.

[0027] When the negative electrode material is one of the X-type metals such as Mg, Zn, or Ca, a monovalent cation [XCl] can also be achieved. + Monovalent anion [XCl3] - Multivalent metal ions X 2+ The reaction equilibrium.

[0028] As a specific instruction: the organic electrolyte comprises one or more of the following: aluminum chloride (AlCl3), aluminum trifluoromethanesulfonate (Al(OTF)3), zinc hexafluorophosphate (Zn(PF6)2), zinc chloride (ZnCl2), zinc trifluoromethanesulfonate (Zn(OTF)2), zinc bis(trifluoromethanesulfonylimide) (Zn(TFSI)2), chromium chloride (CrCl3), ferric trifluoromethanesulfonate (Fe(OTF)3), ferric chloride (FeCl3), vanadium trifluoromethanesulfonate (V(OTF)3), and vanadium sulfonate (VOSO4); and the solvent comprises one or more of the following: propylene carbonate (PC), tetrahydrofuran (THF), dimethyl ethylene glycol (DME), and dimethyl carbonate (DMC); and the concentration is 0.01-14 mol / L.

[0029] The aqueous electrolyte contains one or more of the following solutes: aluminum sulfate (Al2(SO4)3), AlCl3, aluminum nitrate (Al(NO3)3), zinc sulfate (ZnSO4), ZnCl2, Zn(TFSI)2, Zn(OTF)2, potassium hydroxide (KOH), lithium hydroxide (LiOH), and zinc oxide (ZnO); and deionized water with a concentration of 0.01-14 mol / L.

[0030] The ionic liquid electrolyte comprises a mixture of AlCl3 and 1-butyl-3-methylimidazolium chloride (BMImCl) or 1-ethyl-3-methylimidazolium chloride (EMImCl) or urea, wherein the molar ratio of AlCl3 to BMImCl or EMImCl or urea is 0.01-2.

[0031] The solid electrolytes include two categories: the first category is polymer solid electrolytes (PSEs), which are composed of a polymer matrix (such as polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polypropylene carbonate (PPC), polyacrylonitrile (PAN), or polyether blends) and metal salts. The metal salts used include aluminum salts: AlCl3, Al(OTF)3; chromium salts: CrCl3; iron salts: Fe(OTF)3, FeCl3; vanadium salts: V(OTF)3, vanadium sulfide (VOSO4); zinc salts: one or more of ZnCl2, Zn(OTF)2, and Zn(TFSI)2. This type of PSE can also be further composited with inorganic fillers (such as Al2O3, Fe2O3, LiFeO2, V2O5, etc.) to improve its mechanical strength and ionic conductivity. The second category is inorganic solid electrolytes, with representative materials including one or more of aluminum-based chlorine oxides, aluminum fluoride (AlF3)-based framework structures, lithium aluminum titanium phosphate (LATP), lanthanum strontium chromate, and chromium aluminum composite oxides.

[0032] Furthermore, the electrode containing the positive electrode composite material also includes a binder and a conductive additive. The positive electrode composite material accounts for 50% to 98% of the electrode by mass; the binder accounts for 1% to 10% of the electrode by mass; and the conductive additive accounts for 1% to 40% of the electrode by mass.

[0033] The preparation method of the positive electrode composite material can refer to existing technology, including: in a glove box filled with argon gas, at a specified mass ratio m a :m b Weigh material A and material B, and grind them manually in an agate mortar or using a ball mill for 30 minutes to obtain the positive electrode composite material. Further mix it with binder and conductive additives to obtain the electrode material. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the reaction principle of a three-ion secondary battery provided in an embodiment of the present invention;

[0036] Figure 2 The constant current charge-discharge curve of the aluminum metal | aluminum trichloride mixed chloride 1-ethyl-3-methylimidazolium chloride | expanded graphite composite pyrene-4,5,9,10-tetraketone battery (Al|AlCl3-EMImCl|eGr-PTO) provided in Example 1 of the present invention at a current density of 87.5 mA / g.

[0037] Figure 3 The cycling performance diagram of Al|AlCl3-EMImCl|eGr-PTO provided in Example 1 of the present invention is shown, with a voltage range of 1.4-2.2 V and a current density of 87.5 mA / g.

[0038] Figure 4 The rate performance diagram of Al|AlCl3-EMImCl|eGr-PTO provided in Example 1 of the present invention is shown, with 1C = 87.5 mA / g;

[0039] Figure 5 The atomic ratio of Cl in eGr-PTO under different redox states during the first cycle, as characterized by an energy dispersive spectrometer (EDS) provided in Example 1 of this invention;

[0040] Figure 6Auger electron spectrum (AES) of eGr-PTO provided in Embodiment 1 of the present invention when charged to 2.2 V.

[0041] Figure 7 The AES of eGr-PTO provided in Embodiment 1 of the present invention in a discharged state to 1.4 V;

[0042] Figure 8 The Raman results of AlCl3-EMImCl electrolyte under different charging states provided in Example 1 of the present invention;

[0043] Figure 9 The AlCl3-EMImCl electrolyte provided in Embodiment 1 of the present invention under different charge and discharge states 27 Al nuclear magnetic resonance (NMR) spectrum;

[0044] Figure 10 The constant current charge-discharge curve of the aluminum metal | aluminum trichloride mixed chloride 1-ethyl-3-methylimidazolium chloride | natural graphite composite pyrene-4,5,9,10-tetraketone battery (Al|AlCl3-EMImCl|nGr-PTO) provided in Example 2 of the present invention at a current density of 87.5 mA / g.

[0045] Figure 11 The cycling performance diagram of Al|AlCl3-EMImCl|nGr-PTO provided in Example 2 of the present invention is shown, with a voltage range of 1.4-2.2 V and a current density of 87.5 mA / g;

[0046] Figure 12 The constant current charge-discharge curve of the aluminum metal | aluminum trichloride mixed chloride 1-butyl-3-methylimidazolium chloride | expanded graphite composite 2,3,5,6-tetra-o-phthalimide-p-benzoquinone battery (Al|AlCl3-BMImCl|eGr-TPBQ) provided in Example 3 of the present invention at a current density of 43 mA / g.

[0047] Figure 13 The cycling performance diagram of Al|AlCl3-BMImCl|eGr-TPBQ provided in Example 3 of the present invention is shown, with a voltage range of 1.4-2.2 V and a current density of 43 mA / g.

[0048] Figure 14 This is a schematic diagram of the reaction principle of an existing aluminum / graphite dual-ion battery. Detailed Implementation

[0049] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0050] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0051] Example 1

[0052] This embodiment provides a three-ion secondary battery. The negative electrode material is aluminum metal, the electrolyte is aluminum trichloride mixed with 1-ethyl-3-methylimidazolium chloride, and the positive electrode material is expanded graphite composite pyrene-4,5,9,10-tetraone (PTO). The abbreviation is Al|AlCl3-EMImCl|eGr-PTO.

[0053] The three-ion secondary battery described in this embodiment involves three ions: AlCl2. + AlCl4 - Al 3+ During the charging process, AlCl2 + Extracted from the positive electrode eGr-PTO, accompanied by AlCl4 - Embedded eGr-PTO, while Al generation occurs at the negative electrode. 3+ The deposition of the three ions is carried out in a ratio of 2:1:1; the discharge process is the opposite.

[0054] The reaction process is as follows:

[0055] Negative electrode side:

[0056]

[0057] Positive side:

[0058]

[0059] Overall reaction process:

[0060]

[0061] Al|AlCl3-EMImCl|eGr@PTO batteries follow the mechanism of three-ion secondary batteries during charging and discharging.

[0062] Preparation method of eGr-PTO composite material and electrode: In an argon-filled glove box, PTO and eGr (expanded graphite) powders were weighed at a mass ratio of 5:7 and manually ground in an agate mortar for 30 minutes to obtain the eGr-PTO composite material. This composite material was then mixed uniformly with Ketjen Black (KB) and polytetrafluoroethylene (PTFE) at a mass ratio of 8:1:1 and pressed onto a molybdenum mesh as the positive electrode. The ratio of expanded graphite to PTO satisfies... .

[0063] Preparation method of AlCl3-EMImCl ionic liquid electrolyte: AlCl3 and EMImCl are mixed evenly at a molar ratio of 1.3:1.

[0064] Assembly method of Al|AlCl3-EMImCl|eGr@PTO battery: In an argon-filled glove box, the eGr-PTO cathode, aluminum foil, and AlCl3-EMImCl electrolyte are assembled into a coin-type three-ion secondary aluminum battery. The amount of electrolyte added to the Al|AlCl3-EMImCl|eGr@PTO battery is 3 g / (Ah), which is significantly lower than the 52 g / (Ah) of the conventional dual-ion aluminum / graphite battery in prior art 1. The aluminum battery is subjected to constant current charge-discharge test, with a voltage range of 1.4-2.2 V and a current density of 87.5 mA / g.

[0065] from Figure 2 It can be seen that the specific capacity released in this embodiment at a current density of 87.5 mA / g is 71 mAh / g. Benefiting from the three-ion battery reaction mechanism and the smaller amount of electrolyte added, the energy density of the Al|AlCl3-EMImCl|eGr@PTO full cell is calculated to be 84 Wh / kg, which is higher than the 33 Wh / kg of the aluminum / graphite dual-ion battery in prior art 1.

[0066] from Figure 3 It can be seen that the capacity retention rate is 91% after 1000 cycles.

[0067] from Figure 4 It can be seen that as the battery current density increases from 2C to 20C, the capacity decreases from 65 mAh / g to 50 mAh / g, corresponding to a 76% capacity retention.

[0068] from Figure 5 It can be seen that the atomic ratio of Cl in eGr-PTO remains constant under different redox states; from Figure 6-7 It can be seen that the AES signal of eGr-PTO Cl remains unchanged from the charged state to the discharged state, while the AES signal of Al is significantly enhanced; from Figure 8-9 It can be seen that the composition of the AlCl3-EMImCl electrolyte did not change during the charging process.

[0069] Example 2

[0070] This embodiment provides a three-ion secondary battery, an aluminum metal | aluminum trichloride mixed chloride 1-ethyl-3-methylimidazole | natural graphite composite pyrene-4,5,9,10-tetraone battery (Al|AlCl3-EMImCl|nGr-PTO), including its composition, related processes, and performance testing. Aluminum metal (Al) serves as the negative electrode, aluminum trichloride mixed chloride 1-ethyl-3-methylimidazole (AlCl3-EMImCl) as the electrolyte, and natural graphite composite pyrene-4,5,9,10-tetraone (nGr-PTO) as the positive electrode.

[0071] The difference between Example 2 and Example 1 is that the expanded graphite in the positive electrode of Example 1 was replaced with natural graphite, and the molar ratio of AlCl3 to EMImCl in the AlCl3-EMImCl ionic liquid electrolyte was changed from 1.3:1 to 2:1; the ratio of natural graphite to PTO was... .

[0072] The aluminum battery was subjected to constant current charge-discharge testing with a voltage range of 1.4-2.2 V and a current density of 87.5 mA / g.

[0073] from Figure 10 It can be seen that at a current density of 87.5 mA / g, the Al|AlCl3-EMImCl|nGr-PTO battery can release a specific capacity of 66.1 mAh / g; from Figure 11 It can be seen that the Al|AlCl3-EMImCl|nGr-PTO battery retains 97.3% of its capacity after 200 cycles.

[0074] Example 3

[0075] This embodiment provides a three-ion secondary battery, an aluminum metal | aluminum trichloride mixed chloride 1-butyl-3-methylimidazolium chloride | expanded graphite composite 2,3,5,6-tetraphthalimide-p-benzoquinone battery (Al|AlCl3-BMImCl|eGr-TPBQ), detailing its composition, related processes, and performance testing. Aluminum metal (Al) serves as the negative electrode, aluminum trichloride mixed chloride 1-butyl-3-methylimidazolium chloride (AlCl3-BMImCl) is the electrolyte, and expanded graphite composite 2,3,5,6-tetraphthalimide-p-benzoquinone (eGr-TPBQ) is the positive electrode.

[0076] The difference between Example 3 and Example 1 is that PTO in the positive electrode of Example 1 was replaced with TPBQ, and EMImCl in the electrolyte was replaced with BMImCl; the ratio of expanded graphite to TPBQ was [missing information]. .

[0077] Preparation method of eGr-TPBQ composite material and electrode: In an argon-filled glove box, TPBQ and eGr powders were weighed in the corresponding weight ratio and manually ground in an agate mortar for 30 minutes to prepare eGr-TPBQ composite material. Then, it was mixed evenly with Ketjen Black (KB) and polytetrafluoroethylene (PTFE) in a weight ratio of 7:2:1 and pressed onto a molybdenum mesh as a positive electrode.

[0078] Preparation method of AlCl3-BMImCl ionic liquid electrolyte: AlCl3 and BMImCl are mixed evenly at a molar ratio of 1.3:1.

[0079] In an argon-filled glove box, the eGr-TPBQ cathode, aluminum foil, and AlCl3-BMImCl electrolyte were assembled into a coin-type three-ion secondary aluminum battery. The aluminum battery was subjected to constant current charge-discharge testing, with a voltage range of 1.4–2.2 V and a current density of 43 mA / g.

[0080] from Figure 12 It can be seen that the Al|AlCl3-BMImCl|eGr-TPBQ battery can release a specific capacity of 44.6 mAh / g at a current density of 43 mA / g; from Figure 13 It can be seen that the Al|AlCl3-BMImCl|eGr-TPBQ battery retains 94.2% of its capacity after 400 cycles.

[0081] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A positive electrode composite material for a secondary battery, comprising material A and material B, wherein material A is graphite; and material B is an organic electrode material having an operating voltage difference of less than 0.2 V from material A and possessing carbonyl active groups, characterized in that... The mass ratio of material A to material B (m a :m b )satisfy or The C a Let C be the specific capacity of material A. b Let B be the specific mass capacity of material B.

2. The positive electrode composite material as described in claim 1, characterized in that, The mass ratio of material A to material B (m a :m b )satisfy or .

3. The positive electrode composite material as described in claim 1 or claim 2, characterized in that, Material A is one or more of natural graphite or expanded graphite, and material B is one or more of PTO, TPBQ, BAHO or CHO.

4. The application of a positive electrode composite material as described in claim 1 or claim 2 in a secondary battery.

5. The application as described in claim 4, characterized in that, The secondary battery is a multivalent metal ion secondary battery, and the multivalent metal includes one of the following metals: Mg, Zn, Ca, Al, La, Cr, and Fe.

6. A three-ion secondary battery comprising the positive electrode composite material according to any one of claims 1-3, characterized in that, This also includes the negative electrode material, when the mass ratio of material A to material B (m a :m b )satisfy When the negative electrode material is one of Mg, Zn, or Ca metallic materials; when the mass ratio of material A to material B (m a :m b )satisfy In this case, the negative electrode material is one of the metal materials Al, La, Cr, and Fe.

7. The three-ion secondary battery as described in claim 6, characterized in that, This also includes the negative electrode material, when the mass ratio of material A to material B (m a :m b )satisfy When the negative electrode material is one of Mg, Zn, or Ca metallic materials, and the mass ratio of material A to material B (m a :m b )satisfy In this case, the negative electrode material is one of the metal materials Al, La, Cr, and Fe.

8. The three-ion secondary battery as described in claim 6 or claim 7, characterized in that, It also includes an electrolyte, in which the cations contain one of the metals Al, Cr, Fe, V, Zn, Mg, and Ca, and the anions contain one of the metals Cl, Br, and I.

9. The three-ion secondary battery as described in claim 8, characterized in that, The amount of electrolyte used shall not exceed 3 g / (Ah).

10. An electrode comprising the positive electrode composite material according to claim 1 or claim 2, characterized in that, It also includes binders and conductive additives. The positive electrode composite material accounts for 50% to 98% of the mass of the electrode, the binder accounts for 1% to 10% of the mass of the electrode, and the conductive additive accounts for 1% to 40% of the mass of the electrode.

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