Inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery and preparation method thereof

Abstract

The invention belongs to the technical field of flow batteries, and particularly relates to an inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery and a preparation method thereof. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery comprises a positive electrode, a negative electrode and a diaphragm, the positive electrode comprises a positive electrode electrolyte and a positive electrode current collector, and the positive electrode electrolyte is inorganic liquid; the negative electrode comprises a negative electrode electrolyte and a negative electrode current collector, and the negative electrode electrolyte is organic liquid. According to the all-liquid flow battery, good electrochemical reversibility and stability are realized through reasonable selection of positive and negative electrode materials, and the all-liquid flow battery has relatively high energy density and proper working voltage, and shows relatively low voltage attenuation and relatively long service life. The positive electrode and the negative electrode of the battery are made of materials which are rich in raw materials and low in cost, and the requirements of a large-scale energy storage system are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid flow batteries, and in particular relates to an inorganic liquid positive electrode-organic liquid negative electrode full liquid flow battery and a preparation method thereof. Background Art

[0002] Liquid flow battery is an electrochemical energy storage technology proposed by Thaller (NASA Lewis Research Center, Cleveland, United States) in 1974. The liquid flow energy storage battery system consists of a battery stack unit, an electrolyte solution and an electrolyte solution storage and supply unit, a control and management unit, etc. The core of the liquid flow battery system is composed of a battery stack (a battery stack is composed of dozens of single cells that undergo oxidation-reduction reactions) and realize the charging and discharging process, which are connected in series according to specific requirements. The structure is similar to that of a fuel cell stack.

[0003] Liquid flow battery is a new type of battery. Liquid flow battery is a high-performance battery that uses positive and negative electrolytes to separate and circulate separately. It has the characteristics of high capacity, wide application field (environment), and long cycle life. It is currently a new energy product. Redox flow battery is a new type of large-capacity electrochemical energy storage device that is being actively developed. It is different from batteries that usually use solid material electrodes or gas electrodes. Its active material is a flowing electrolyte solution. Its most notable feature is large-scale power storage. Under the situation of the growing call for the extensive use of renewable energy, liquid flow battery has become one of the current research hotspots. All-vanadium liquid flow battery is the most in-depth and representative liquid flow battery at present, but it has the problems of low energy density and high cost. The development of new low-cost liquid flow battery systems and technologies is the key to solving the bottleneck problem of the current development of liquid flow battery industrialization. Compared with vanadium, iron, as one of the most abundant metal elements in the earth, has significant cost and resource advantages. Therefore, all-iron liquid flow battery has attracted much attention in recent years.

[0004] For example, the Chinese patent application with application number: 202410069885.4 discloses an alkaline all-iron flow battery electrolyte, a preparation method and a flow battery, which includes the following components in molar concentrations: ferrocyanide 0.5M to 1.4M, alkaline solution 0.1M to 2M, surfactant or permeant 0.001M to 0.5M. By adding a surfactant or permeant that can change the tension of the diaphragm to the positive electrode electrolyte of the alkaline all-iron flow battery, the surface tension of the solid-liquid interface or the force between particles can be reduced, so that impurities form uniform particles and disperse, and are not easy to agglomerate or adhere to the surface of the diaphragm and electrode materials, so that ions can pass through the diaphragm and contact the electrode more easily, thereby improving the proton transfer rate of the diaphragm, contributing to the long-term stability of the battery, and can repair the battery in operation. However, in the all-iron flow battery, due to the poor reversibility of the electrochemical reaction of the iron negative electrode, iron is easily deposited at the negative electrode, resulting in the formation of dendrites, which not only greatly reduces the operating efficiency of the battery and reduces the battery capacity, but also has the risk of clogging the ion conduction membrane. Summary of the invention

[0005] Based on the above technical background, the main purpose of the present invention is to provide a low-cost inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery and a preparation method thereof to overcome the shortcomings of the prior art.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0007] The first aspect of the present invention is to provide an inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery, wherein the inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery comprises a positive electrode, a negative electrode and a separator;

[0008] The positive electrode comprises a positive electrode electrolyte and a positive electrode current collector, and the positive electrode electrolyte is an inorganic liquid;

[0009] The negative electrode comprises a negative electrode electrolyte and a negative electrode current collector, and the negative electrode electrolyte is an organic liquid.

[0010] Preferably, the positive electrode electrolyte is prepared by adding a positive electrode material to a salt solution, and the positive electrode material is selected from one or more cyanides of variable valence transition metal ions;

[0011] Preferably, the salt solution is a KCl solution.

[0012] More preferably, the concentration of the positive electrode material in the positive electrode electrolyte is 0.005 to 0.6 mol / L.

[0013] Preferably, the positive electrode current collector is a carbon rod, carbon paper or nickel foam.

[0014] Preferably, the negative electrode electrolyte is prepared by adding a negative electrode material into a mixed solution, and the negative electrode material is selected from one or more nitrogen-containing benzene heterocyclic organic compounds;

[0015] Preferably, the mixed solution is prepared by dissolving KOH in a mixed solvent, the mixed solvent is obtained by mixing water and ethanol, the volume percentage of water in the mixed solvent is 40-45%, and the rest is ethanol.

[0016] More preferably, the concentration of the negative electrode material in the negative electrode electrolyte is 0.005 to 3 mol / L.

[0017] Preferably, the negative electrode current collector is carbon paper or nickel foam with a catalyst loaded on the surface, and the catalyst is selected from one or more of Ni, Ni / P, Pd, Ru, MoNi4, and Pd / C.

[0018] Preferably, the membrane is a proton exchange membrane.

[0019] The second aspect of the present invention is to provide a method for preparing the inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to the first aspect of the present invention, the preparation method comprising the following steps:

[0020] Step 1, dissolving the positive electrode material in a salt solution to obtain a positive electrode electrolyte, and immersing the positive electrode current collector in the positive electrode electrolyte to obtain a positive electrode;

[0021] Step 2, dissolving the negative electrode material in the mixed solution to obtain a negative electrode electrolyte, and immersing the negative electrode current collector in the negative electrode electrolyte to obtain a negative electrode;

[0022] Step 3: Assemble the positive electrode, negative electrode and separator to obtain a fully liquid flow battery.

[0023] The beneficial effects of the present invention are:

[0024] (1) The all-liquid flow battery of the present invention achieves good electrochemical reversibility and stability through the rational selection of positive and negative electrode materials. The all-liquid flow battery has a high energy density and a suitable operating voltage, and exhibits low voltage decay and a long service life.

[0025] (2) The all-liquid flow battery described in the present invention is based on organic liquid electrochemical hydrogen storage. For the first time, it uses low-cost cyanide containing variable-valence transition metal ions and nitrogen-containing benzene heterocyclic organic compounds to form an all-liquid flow battery, which effectively reduces the cost of the battery system and can achieve stable circulation.

[0026] (3) The all-liquid flow battery system reduces the interfacial impedance and mass transfer impedance during the electrochemical reaction process, reduces the energy loss of the battery, and thus improves the energy conversion efficiency of the battery.

[0027] (4) The all-liquid flow battery does not generate hydrogen during the entire reaction process, and can directly utilize the electrochemical reaction of organic liquid and water to provide protons for energy storage and conversion, shortening the energy conversion path, thereby further improving the energy conversion efficiency.

[0028] (5) The positive electrode reaction of the all-liquid flow battery described in the present invention is highly reversible and does not require the addition of additional catalysts, thereby further reducing the cost of the battery system.

[0029] (6) The positive and negative electrodes of the all-liquid flow battery are made of materials with abundant raw materials and low cost, which is low in cost and very suitable for the needs of large-scale energy storage systems. It has good application prospects in the field of liquid flow battery technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The cyclic voltammetry curve of the all-liquid flow battery prepared in Example 1 is shown;

[0031] Figure 2 The charge and discharge curves of the all-liquid flow battery prepared in Example 1 are shown. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below, and the characteristics and advantages of the present invention will become clearer and more distinct with the description.

[0033] A first aspect of the present invention is to provide an inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery, wherein the inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery comprises a positive electrode, a negative electrode and a separator.

[0034] The positive electrode includes a positive electrode electrolyte and a positive electrode current collector.

[0035] The positive electrode electrolyte is an inorganic liquid, and the positive electrode electrolyte is prepared by adding a positive electrode material into a salt solution, and the positive electrode material is selected from one or more cyanides of variable valence transition metal ions.

[0036] Preferably, the positive electrode material is K4Fe(CN)6 or K3Fe(CN)6, more preferably K4Fe(CN)6.

[0037] The positive electrode reaction of K4Fe(CN)6 / K3Fe(CN)6 is shown in formula (1):

[0038]

[0039] The salt solution is KCl solution.

[0040] Preferably, the solution is a KCl solution with a concentration of 0.1 to 4.5 mol / L, and more preferably, the solution is a KCl solution with a concentration of 1 mol / L.

[0041] The concentration of the positive electrode material in the positive electrode electrolyte is 0.005-0.6 mol / L.

[0042] Preferably, the concentration of the positive electrode material in the positive electrode electrolyte is 0.01 mol / L.

[0043] The positive electrode current collector is an inert electrode, preferably a carbon rod, carbon paper or nickel foam, more preferably carbon paper.

[0044] The negative electrode includes a negative electrode electrolyte and a negative electrode current collector.

[0045] The negative electrode liquid is an organic liquid, the negative electrode electrolyte is prepared by adding a negative electrode material into a mixed solution, and the negative electrode material is an organic liquid material selected from one or more nitrogen-containing benzene heterocyclic organic compounds.

[0046] Preferably, the negative electrode material is selected from quinoline, quinoxaline and their alkyl-containing derivatives.

[0047] More preferably, the negative electrode material is quinoline.

[0048] The negative electrode reaction is a dehydrogenation reaction of a heterocyclic compound, as shown in formula (2):

[0049]

[0050] In formula (2), X can be a carbon or nitrogen atom, and R represents an alkyl group.

[0051] The mixed solution is prepared by dissolving KOH in a mixed solvent, and the mixed solvent is obtained by mixing water and ethanol. The volume percentage of water in the mixed solvent is 40-45%, and the rest is ethanol.

[0052] Preferably, the volume percentage of water in the mixed solvent is 44%, and the volume percentage of ethanol is 56%.

[0053] The concentration of KOH in the mixed solution is 0.1-5.5 mol / L. Preferably, the concentration of KOH in the mixed solution is 1 mol / L.

[0054] The concentration of the negative electrode material in the negative electrode electrolyte is 0.005-3 mol / L. Preferably, the concentration of the negative electrode material in the negative electrode electrolyte is 0.01 mol / L.

[0055] The negative electrode current collector is carbon paper or nickel foam with a catalyst loaded on the surface, and the catalyst is selected from one or more of Ni, Ni / P, Pd, Ru, MoNi4, and Pd / C.

[0056] Preferably, the negative electrode current collector is nickel foam with a Pd / C catalyst loaded on the surface.

[0057] The membrane is a proton exchange membrane.

[0058] The all-liquid flow battery of the present invention uses a new type of inorganic compound salt solution as the positive electrode material and an organic liquid as the negative electrode material, and realizes energy conversion through the change of ion valence in the positive electrode compound and the addition and dehydrogenation reaction in the negative electrode organic matter.

[0059] The second aspect of the present invention is to provide a method for preparing the inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to the first aspect of the present invention, the preparation method comprising the following steps:

[0060] Step 1, dissolving the positive electrode material in a salt solution to obtain a positive electrode electrolyte, and immersing the positive electrode current collector in the positive electrode electrolyte to obtain a positive electrode;

[0061] Step 2, dissolving the negative electrode material in the mixed solution to obtain a negative electrode electrolyte, and immersing the negative electrode current collector in the negative electrode electrolyte to obtain a negative electrode;

[0062] Step 3: Assemble the positive electrode, negative electrode and separator to obtain a fully liquid flow battery.

[0063] The above steps are described in detail below.

[0064] In step 1, the positive electrode material K4Fe(CN)6 is dissolved in a 0.1-4.5 mol / L KCl solution to obtain a positive electrode electrolyte, wherein the concentration of K4Fe(CN)6 in the positive electrode electrolyte is 0.005-0.6 mol / L, and the positive electrode current collector carbon paper is immersed in the KCl solution to obtain a positive electrode.

[0065] Preferably, the positive electrode material K4Fe(CN)6 is dissolved in a 1 mol / L KCl solution to obtain a positive electrode electrolyte, the concentration of K4Fe(CN)6 in the positive electrode electrolyte is 0.01 mol / L, and the positive electrode current collector carbon paper is immersed in the KCl solution to obtain a positive electrode.

[0066] In step 2, quinoline, a negative electrode material, is dissolved in a 0.1-5.5 mol / L KOH mixed solution to obtain a negative electrode electrolyte, the mixed solution is prepared by dissolving KOH in a mixed solvent, the mixed solvent is obtained by mixing water and ethanol, the volume percentage of water in the mixed solvent is 40-45%, and the rest is ethanol, the concentration of quinoline in the negative electrode electrolyte is 0.005-3 mol / L, and carbon paper or nickel foam with a catalyst loaded on the surface is immersed in the negative electrode electrolyte to obtain a negative electrode.

[0067] Preferably, the negative electrode material quinoline is dissolved in a 1 mol / L KOH mixed solution to obtain a negative electrode electrolyte, the mixed solution is prepared by dissolving KOH in a mixed solvent, the mixed solvent is obtained by mixing water and ethanol, the volume percentage of water in the mixed solvent is 44%, and the rest is ethanol, the concentration of quinoline in the negative electrode electrolyte is 0.01 mol / L, and carbon paper or nickel foam with a catalyst loaded on the surface is immersed in the negative electrode electrolyte to obtain a negative electrode.

[0068] Example

[0069] The present invention is further described below by specific examples, which are limited to illustrating the present invention but not to limiting the scope of the present invention. The raw materials used in the examples of the present invention were all purchased.

[0070] Example 1

[0071] The present embodiment provides a full liquid flow battery, which includes a positive electrode, a negative electrode and a separator.

[0072] The positive electrode material is K4Fe(CN)6, which is dissolved in a 1 mol / L KCl solution as a positive electrolyte, and the concentration of K4Fe(CN)6 in the positive electrolyte is 0.01 mol / L. Carbon paper is soaked in the positive electrolyte as a positive electrode.

[0073] The negative electrode material is quinoline, which is dissolved in a 1 mol / L KOH mixed solution (containing 44 vol% H2O and 56 vol% EtOH (ethanol)) as the negative electrode electrolyte, and the concentration of quinoline in the negative electrode electrolyte is 0.01 mol / L. A nickel foam loaded Pd / C catalyst is used and immersed in the negative electrode electrolyte as the negative electrode.

[0074] The diaphragm is a proton exchange membrane. The positive electrode, the negative electrode and the diaphragm are assembled to obtain a fully liquid flow battery.

[0075] The overall reaction equation of the all-liquid flow battery is: 4H2O+C9H7N+

[0076]

[0077] The equation for the negative electrode reaction is:

[0078]

[0079] Positive electrode reaction:

[0080] Example 2

[0081] The present embodiment provides a full liquid flow battery, which includes a positive electrode, a negative electrode and a separator.

[0082] The positive electrode material is K4Fe(CN)6, which is dissolved in a 0.1 mol / L KCl solution as a positive electrolyte, and the concentration of K4Fe(CN)6 in the positive electrolyte is 0.005 mol / L. Carbon paper is soaked in the positive electrolyte as a positive electrode.

[0083] The negative electrode material is quinoline, which is dissolved in a 0.1 mol / L KOH mixed solution (containing 40 vol% H2O and 60 vol% EtOH (ethanol)) as the negative electrode electrolyte, and the concentration of quinoline in the negative electrode electrolyte is 0.005 mol / L. A nickel foam loaded Pd / C catalyst is used and immersed in the negative electrode electrolyte as the negative electrode.

[0084] The diaphragm is a proton exchange membrane. The positive electrode, the negative electrode and the diaphragm are assembled to obtain a fully liquid flow battery.

[0085] Example 3

[0086] The present embodiment provides a full liquid flow battery, which includes a positive electrode, a negative electrode and a separator.

[0087] The positive electrode material is K4Fe(CN)6, which is dissolved in a 4.5 mol / L KCl solution as a positive electrolyte, and the concentration of K4Fe(CN)6 in the positive electrolyte is 0.6 mol / L. Carbon paper is soaked in the positive electrolyte as a positive electrode.

[0088] The negative electrode material is quinoline, which is dissolved in a 5.5 mol / L KOH mixed solution (containing 45 vol% H2O and 55 vol% EtOH (ethanol)) as the negative electrode electrolyte, and the concentration of quinoline in the negative electrode electrolyte is 3 mol / L. A nickel foam loaded Pd / C catalyst is used and immersed in the negative electrode electrolyte as the negative electrode.

[0089] The diaphragm is a proton exchange membrane. The positive electrode, the negative electrode and the diaphragm are assembled to obtain a fully liquid flow battery.

[0090] Experimental example

[0091] Experimental Example 1 Electrochemical Performance Test

[0092] The electrochemical performance of the all-liquid flow battery prepared in Example 1 was tested. Before the test, the all-liquid flow battery was activated. The activation procedure of the battery was as follows: at 100 mA / cm 2 Charge at a current density of 50 mA / cm for 4 h. 2 Charge for 2 h at a current density of 100 mA / cm 2 The discharge starts at a current density of 1000V and the cut-off voltage is set to 0V (vs. RHE) to complete one activation. After activation, the charge and discharge cycle test can be performed. The cyclic voltammetry curve of the all-liquid flow battery is measured as follows: Figure 1 As shown, the charge and discharge curves are Figure 2 shown.

[0093] from Figure 1 It can be seen that the all-liquid flow battery has an obvious oxidation peak at 0.9 V, corresponding to [Fe(CN)6] 4- Transformed to [Fe(CN)6] 3- Quinoline is hydrogenated to tetrahydroquinoline; there is an obvious reduction peak at 0.3V, corresponding to [Fe(CN)6] 3- Transformed to [Fe(CN)6] 4- The results show that the redox reaction of the all-liquid flow battery of the present invention has good electrochemical reversibility and suitable reaction potential, and can be effectively charged and discharged.

[0094] from Figure 2 It can be seen that the all-liquid flow battery described in the present invention has a stable voltage platform and charge and discharge capacity. The charging platform voltage is 0.7V, the discharging platform voltage is 0.3V, and the discharge capacity of the organic liquid negative electrode material is calculated to be 13.56mAh / g.

[0095] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. An inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery, characterized in that: The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery comprises a positive electrode, a negative electrode and a separator; The positive electrode comprises a positive electrode electrolyte and a positive electrode current collector, and the positive electrode electrolyte is an inorganic liquid; The negative electrode comprises a negative electrode electrolyte and a negative electrode current collector, and the negative electrode electrolyte is an organic liquid.

2. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to claim 1, characterized in that: The positive electrode electrolyte is prepared by adding a positive electrode material to a salt solution, wherein the positive electrode material is selected from one or more cyanides of variable valence transition metal ions; The salt solution is KCl solution.

3. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to claim 2, characterized in that: The concentration of the positive electrode material in the positive electrode electrolyte is 0.005-0.6 mol / L.

4. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to claim 1, characterized in that: The positive electrode current collector is a carbon rod, carbon paper or nickel foam.

5. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to claim 1, characterized in that: The negative electrode electrolyte is prepared by adding a negative electrode material into a mixed solution, wherein the negative electrode material is selected from one or more nitrogen-containing benzene heterocyclic organic compounds; The mixed solution is prepared by dissolving KOH in a mixed solvent, and the mixed solvent is obtained by mixing water and ethanol. The volume percentage of water in the mixed solvent is 40-45%, and the rest is ethanol.

6. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to claim 5, characterized in that: The concentration of the negative electrode material in the negative electrode electrolyte is 0.005-3 mol / L.

7. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to claim 1, characterized in that: The negative electrode current collector is carbon paper or nickel foam with a catalyst loaded on the surface, and the catalyst is selected from one or more of Ni, Ni / P, Pd, Ru, MoNi4, and Pd / C.

8. The inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to claim 1, characterized in that: The membrane is a proton exchange membrane.

9. A method for preparing an inorganic liquid positive electrode-organic liquid negative electrode all-liquid flow battery according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: Step 1, dissolving the positive electrode material in a salt solution to obtain a positive electrode electrolyte, and immersing the positive electrode current collector in the positive electrode electrolyte to obtain a positive electrode; Step 2, dissolving the negative electrode material in the mixed solution to obtain a negative electrode electrolyte, and immersing the negative electrode current collector in the negative electrode electrolyte to obtain a negative electrode; Step 3: Assemble the positive electrode, negative electrode and separator to obtain a fully liquid flow battery.

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