Ni-MH batteries

Ni-MH batteries electrolyte composition, the role of electrolyte in the battery

Ni-MH batteries electrolyte composition, the use of electrolyte in the battery. Electrolyte is one of the four key materials of lithium-ion batteries and is called the "blood" of lithium-ion batteries. The electrolyte in the battery is made of dilute sulfuric acid and distilled water, and the color is colorless and transparent. The density is generally 1.24-1.30 grams per cubic centimeter.

The electrolyte composition of lithium-ion batteries is mainly composed of three parts

1. Solvent: cyclic carbonate (PC, EC); chain carbonate (DEC, DMC, EMC); carboxylic acid esters (MF, MA, EA, MA, MP, etc.) (used to dissolve lithium salts).

2. Lithium salts: LiPF6, LiClO4, LiBF4, LiAsF6, etc.

3. Additives: film-forming additives, conductive additives, flame retardant additives, overcharge protection additives, additives to control the H2O and HF content in Ni-MH batteries electrolytes, additives to improve low-temperature performance, and multifunctional additives.

As the blood of lithium-ion batteries, electrolytes bear the heavy responsibility of transporting lithium ions. The quality of electrolytes will directly affect the performance of lithium-ion batteries, and also affect the safety of lithium-ion batteries to a certain extent.

Important components of Ni-MH batteries electrolytes

1. Ethylene carbonate: molecular formula: C3H4O3, transparent colorless liquid (35°C), crystalline solid at room temperature, a good solvent for polyacrylonitrile and polyvinyl chloride.

2. Propylene carbonate, colorless and odorless, or light yellow transparent liquid, soluble in water and carbon tetrachloride, miscible with ether, acetone, benzene, etc. This product should be stored in a cool, ventilated, dry place, away from fire sources, and stored and transported in accordance with general low-toxic chemicals.

3. Diethyl carbonate, colorless liquid, slight odor; vapor pressure 1.33kPa/23.8℃; flash point 25℃ (flammable liquid can evaporate into vapor and run into the air.

4. Dimethyl carbonate is a non-toxic, environmentally friendly, and widely used chemical raw material; it also has a high evaporation temperature and a fast evaporation rate.

5. Ethyl methyl carbonate, a colorless, transparent liquid, is a high-tech, high-value-added chemical product that has emerged in recent years. It is an excellent solvent for Ni-MH batteries electrolytes. This product should be stored in a cool, ventilated, dry place. Dry place, stored and transported according to the regulations for flammable chemicals.

6. Lithium hexafluorophosphate, white crystals or powder, highly deliquescent; when exposed to air or heated, lithium hexafluorophosphate decomposes rapidly in the air due to the use of water vapor, releasing PF5 and generating white smoke.

7. Phosphorus pentafluoride, a phosphorus halogen compound. Phosphorus pentafluoride is a colorless and foul-smelling gas at room temperature and pressure, which is highly irritating to the skin, eyes, and mucous membranes. Phosphorus pentafluoride is used as a catalyst for polymerization reactions.

Uses of electrolyte in batteries

1. Start 1. Use for electrochemical reaction.

When the battery is discharged, the electrode plate absorbs sulfuric acid in the electrolyte and releases electrical energy. Without electrolyte, the battery cannot release electrical energy. When the battery is charged, the electrode plate releases the sulfuric acid absorbed during discharge, so that the electrode plate returns to its initial state;

2. Use for conductivity.

The positive and negative electrode plates of the battery are insulated from each other. Without electrolyte, a current loop cannot be formed. The electrolyte is prepared by adding sulfuric acid to non-conductive pure distilled water. After adding sulfuric acid, distilled water becomes a conductive medium. There is a conductive medium between the positive and negative electrode plates of the battery. Only when the load is connected to the external circuit and a complete current loop is formed, the current can flow smoothly in the battery, and only when the current passes through the electrode plate can the electrochemical reaction occur, charging or discharging.

The above are the components of Ni-MH batteries electrolyte and the uses of electrolyte in batteries. The electrolyte used in lead-acid batteries is a sulfuric acid solution with a concentration of 37~42%. The general method of preparation is to dilute concentrated sulfuric acid with water. As one of the key materials of lithium-ion batteries, the electrolyte connects the positive and negative electrodes of the battery. It must not only have high lithium ion conductivity, but also have excellent electronic insulation.

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