CN102332596B - All-iron redox energy storage cell, electrolyte of battery and preparation method of electrolyte - Google Patents

Abstract

The invention discloses an all-iron redox energy storage battery, an electrolyte of the battery and a preparation method thereof. The all-iron redox energy storage battery comprises a divalent iron ion electrolyte, which consists of an inorganic salt of divalent iron ions and It consists of an aqueous solution of supporting electrolytes and additives. The all-iron redox energy storage battery of the present invention adopts non-toxic and harmless iron inorganic salt as the active material, and the active materials of the positive and negative electrodes are all the same iron element, but different oxidation-reduction potentials are formed according to different valence states , using the electrochemical method to realize the storage and release of electric energy, avoiding the toxicity of the vanadium electrolyte, and also greatly reducing the price of the electrolyte, it is expected to be widely used in large-scale energy storage power stations.

Description

All-iron redox energy storage battery and battery electrolyte and preparation method thereof

technical field

The invention relates to a redox energy storage battery in the technical field of secondary batteries, in particular to an all-iron redox energy storage battery, an electrolyte solution of the battery and a preparation method thereof.

Background technique

With the increasing calls for global environmental protection, the development of clean energy continues to heat up, and the demand for large-scale energy storage batteries used in conjunction with renewable energy such as wind energy and solar energy is also increasing. For example, all-vanadium redox flow batteries and sodium-sulfur batteries that are close to commercial applications.

As an indispensable component system of smart grid - energy storage battery, large capacity, low cost, long life and green environmental protection are the basic characteristics that energy storage battery must possess, such as Chinese patent application number 200910148218.0 "for all vanadium liquid flow Electrolyte for battery and its preparation method, and all-vanadium redox flow battery including the electrolyte", which introduces the electrolyte used for all-vanadium redox flow battery and introduces the working principle of all-vanadium redox flow battery. The patent reads: "The electrolytic solution for an all-vanadium redox flow battery of the present invention includes a positive electrode electrolyte and a negative electrode electrolyte containing vanadium-containing ions and sulfate ions, and the concentration of sulfate ions in the positive electrode electrolyte is greater than that of the negative electrode. The sulfate ion concentration in the electrolyte, the total vanadium concentration in the positive electrode electrolyte and the negative electrode electrolyte are both 2.0-8.0MOL/L.The preparation method of the electrolyte for the all-vanadium redox flow battery of the present invention comprises: respectively One or more vanadium oxides and an optional reducing agent are dissolved in a sulfuric acid solution with a first concentration and a second concentration to obtain a positive electrode electrolyte precursor and a negative electrode electrolytic solution with a total vanadium concentration of 2.0-8.0MOL/L liquid precursor, wherein the first concentration is greater than the second concentration; and respectively electrolyzing the positive electrode electrolyte precursor and the negative electrode electrolyte precursor to obtain the positive electrode electrolyte and the negative electrode electrolyte of the all-vanadium redox flow battery.” Although the technical solution of the patent It can bring a certain effect, but because the metal vanadium salt used in the all-vanadium redox flow battery is still relatively expensive and has certain toxicity, researchers are working hard to find a suitable redox couple and a cheap electrolyte. Moreover, it is environmentally friendly and opens up a new direction for the research of energy storage batteries.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides an all-iron redox energy storage battery, an electrolyte of the battery and a preparation method thereof. The battery adopts the electrolyte of iron ions, which is cheap and environmentally friendly.

To achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

The invention provides an electrolyte solution for an all-iron redox energy storage battery, which is an electrolyte solution containing divalent iron ions, and is composed of an inorganic salt of the divalent iron ions and an aqueous solution of a supporting electrolyte.

The inorganic salt of divalent iron ion can be ferrous sulfate, ferrous chloride, ferrous nitrate, etc., and the concentration is between 0.1-4M. Its function is to constitute the electrochemically active material of the all-iron redox energy storage battery. The initial active material is all composed of divalent iron. When charging for the first time, the divalent iron is reduced to elemental iron at the negative electrode and deposited on the electrode surface of the negative electrode to form an active material pair of Fe ²⁺ /Fe; On the positive electrode, 2-valent iron is oxidized to 3-valent iron, forming an active material pair of Fe ³⁺ /Fe ²⁺ . In this way, the charging and discharging cycle of the battery can be formed to realize the function of the energy storage battery.

The supporting electrolyte is sodium sulfate, potassium sulfate, ammonium sulfate, sodium chloride, potassium chloride, ammonium chloride, calcium chloride, and the concentration is between 0.05-5M. Its function is to increase the conductivity of the electrolyte, reduce the internal resistance of the battery, and improve the performance of the battery. Especially at the end of the charge state of the negative electrode, most of the divalent iron is reduced to metallic iron and deposited on the porous electrode. At this time, it mainly depends on the supporting electrolyte to realize the internal conduction of ions.

Further, in order to obtain a better effect, additives can also be added in the above-mentioned electrolyte, and the additives are one of zinc sulfate, manganese sulfate, chromium sulfate, zinc chloride, manganese chloride, and chromium chloride, with a concentration of Between 0.01 and 0.10M. Its function is to reduce the self-discharge of the battery and improve the efficiency of the battery.

The invention provides a method for preparing an electrolyte of an all-iron redox energy storage battery, comprising the following steps:

The first step, weighing the inorganic salt and electrolyte of divalent iron ion, or and additive;

In the second step, add deionized water and stir until the solution is completely dissolved;

In the third step, add deionized water dropwise until the volume of the solution reaches the set value.

The present invention also provides an all-iron redox energy storage battery, which comprises the above-mentioned electrolyte solution containing divalent iron ions.

In the present invention, the active material of the all-iron redox energy storage battery is an electrolyte containing divalent iron ions. In the charging state: the electrolyte containing divalent iron ions is reduced to metallic iron at the negative electrode and oxidized to trivalent iron at the positive electrode; Discharge state: the metallic iron at the negative electrode is oxidized to ferric ions, and the trivalent iron at the positive electrode is reduced to ferric iron. By repeating this cycle, electrical energy can be stored and released according to the different redox states of iron. The operating temperature of the battery is between 20 and 80°C.

For the above electrochemical reactions, the corresponding electrode potentials are shown in the reaction formulas (1), (2), (3):

Negative electrode electrochemical reaction: Fe ²⁺ + 2e ^- = Fe E = -0.44V vs. SHE (1)

Positive electrochemical reaction: 2Fe ²⁺ = 2Fe ³⁺ + 2e ^- E = 0.77V vs. SHE (2)

Total electrode reaction: 3Fe ²⁺ = 2Fe ³⁺ + Fe △V=1.21V (3)

The all-iron redox energy storage battery proposed by the present invention adopts non-toxic and harmless iron inorganic salt as the active material. Reduction potential, using electrochemical methods, realizes the storage and release of electric energy, avoids the toxicity of vanadium electrolyte, and also greatly reduces the price of electrolyte, and is expected to be widely used in large-scale energy storage power stations.

Detailed ways

The embodiments of the present invention are described in detail below: the present embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation and specific operation process are provided, but the protection scope of the present invention is not limited to the following implementation example. the

Example 1

Weigh 25.02 grams of ferrous sulfate heptahydrate, 0.87 grams of potassium sulfate, and 0.287 grams of zinc sulfate into a 1500mL container, add 600mL of deionized water, stir until the solution is completely dissolved, then add deionized water dropwise until the solution is The volume reaches 900mL.

Put 300mL of the above-mentioned electrolyte into the negative electrode electrolyte storage tank of the all-iron redox energy storage battery, put 600mL into the positive electrode electrolyte storage tank, and enter the single cell with an active area of 9cm2 at a rate of 30mL/min. The current of 200mA is charged and discharged, the battery capacity is 1.28Ah, the current efficiency is 91%, and the voltage efficiency is 55%.

Example 2

Weigh 974.99 grams of ferrous chloride tetrahydrate, 335.48 grams of potassium chloride, and 17.81 grams of manganese chloride into a 1500mL container, add 600mL of deionized water, stir until the solution is completely dissolved, and then add deionized water until the volume of the solution reaches 900 mL.

Put 300mL of the above-mentioned electrolyte into the negative electrode electrolyte storage tank of the all-iron redox energy storage battery, put 600mL into the positive electrode electrolyte storage tank, and enter the single cell with an active area of 9cm2 at a rate of 30mL/min. Charge and discharge at a current of 200mA, the battery capacity is 51.46Ah, the current efficiency is 95%, and the voltage efficiency is 58%.

Example 3

Weigh 466.77 grams of ferrous chloride tetrahydrate, 120.36 grams of ammonium chloride, and 6.13 grams of zinc chloride into a 1500mL container, add 600mL of deionized water, stir until the solution is completely dissolved, and then add deionized water until the volume of the solution reaches 900 mL.

Put 300mL of the above-mentioned electrolyte into the negative electrode electrolyte storage tank of the all-iron redox energy storage battery, put 600mL into the positive electrode electrolyte storage tank, and enter the single cell with an active area of 9cm2 at a rate of 30mL/min. The current of 200mA is charged and discharged, the battery capacity is 25.73Ah, the current efficiency is 93%, and the voltage efficiency is 53%.

Example 4

Weigh 466.77 grams of ferrous chloride tetrahydrate and 120.36 grams of ammonium chloride, put them together into a 1500mL container, add 600mL of deionized water, stir until the solution is completely dissolved, then add deionized water dropwise until the volume of the solution reaches up to 900mL.

Put 300mL of the above-mentioned electrolyte into the negative electrode electrolyte storage tank of the all-iron redox energy storage battery, put 600mL into the positive electrode electrolyte storage tank, and enter the single cell with an active area of 9cm2 at a rate of 30mL/min. The current of 200mA is charged and discharged, the battery capacity is 25.73Ah, the current efficiency is 93%, and the voltage efficiency is 53%.

Example 5

Weigh 4667.7 grams of ferrous chloride tetrahydrate, 1203.6 grams of ammonium chloride, and 61.3 grams of zinc chloride into a 15L container, add 6L of deionized water, stir until the solution is completely dissolved, and then dropwise add deionized water until the volume of the solution reaches 9 L.

Put 3L of the above-mentioned electrolyte into the negative electrode electrolyte storage tank of the all-iron redox energy storage battery, put 6L into the positive electrode electrolyte storage tank, and enter the single cell with an active area of 90cm2 at a rate of 300mL/min. The current of 200mA is charged and discharged, the battery capacity is 257.3Ah, the current efficiency is 93%, and the voltage efficiency is 55%.

Example 6

Weigh 46677 grams of ferrous chloride tetrahydrate, 12036 grams of ammonium chloride, and 613 grams of zinc chloride into a 150L container, add 60L of deionized water, stir until the solution is completely dissolved, and then add deionized water until the volume of the solution reaches 90 L.

Put 30L of the above-mentioned electrolyte into the negative electrode electrolyte storage tank of the all-iron redox energy storage battery, and put 60L into the positive electrode electrolyte storage tank. In the formed battery stack, charge and discharge are carried out at a current of 200mA, the battery capacity is 2573Ah, the current efficiency is 95%, and the voltage efficiency is 60%.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. Various modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the above disclosure. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (3)

1. the electrolyte of a full iron redox energy storage cell, it is characterized in that: this electrolyte is a kind of divalent iron ion electrolyte that contains, and the inorganic salts of divalent iron ion and the aqueous solution of supporting electrolyte, is consisted of;

Perhaps the aqueous solution by inorganic salts, supporting electrolyte and the additive of divalent iron ion is formed;

The inorganic salts of described divalent iron ion are ferrous sulfate, frerrous chloride, and a kind of in ferrous nitrate, concentration is between 0.1～4M;

Described supporting electrolyte is sodium sulphate, potassium sulfate, and ammonium sulfate, sodium chloride, potassium chloride, ammonium chloride, a kind of in calcium chloride, concentration is between 0.05～5M;

Described additive is zinc sulfate, manganese sulfate, and chromium sulfate, zinc chloride, manganese chloride, a kind of in chromium chloride, concentration is between 0.01～0.10M.

2. the preparation method of the electrolyte of a full iron redox energy storage cell as claimed in claim 1, is characterized in that comprising the steps:

The first step, take inorganic salts and the electrolyte of divalent iron ion, or and additive;

Second step, add deionized water, stirs, until solution all dissolves;

The 3rd step, then drip deionized water until the volume of solution reaches set point.

3. a full iron redox energy storage cell, is characterized in that, this power brick contains electrolyte claimed in claim 1.