RU2582652C1 - Electrolyte for lead-acid accumulators - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to chemical current sources, particularly to compositions of electrolytes, used in lead-acid accumulators, and can be used for production of accumulator batteries for electric vehicles, automobiles with combined power plant, as well as for vehicles with traditional petrol engine. Electrolyte contains, wt %: borate methylphosphite 0.6-0.8, perfluoropolyether acids flouranhydrides with molecular weight of 800-1,000 0.1-0.3, Chitosan 0.1-0.3, sulphuric acid 20.0-30.0, and distilled water up to 100.

EFFECT: technical result is improved electrical and operating characteristics of lead accumulator, as well as increasing its service life.

1 cl, 2 tbl, 5 ex

Description

The invention relates to chemical current sources, in particular to electrolyte compositions used in lead acid batteries, and can be used in the manufacture of rechargeable batteries for electric vehicles, cars with combined power plants, as well as for cars with a traditional gasoline engine.

The main disadvantage of a lead-acid battery is a change over time in its electrical and operational characteristics due to irreversible wear processes. Battery wear processes include:

- sulfation of the electrode plates, which consists in the formation of large crystallites of lead sulfate, preventing the flow of reversible current-forming processes;

- corrosion of the electrodes, which is the electrochemical processes of oxidation and dissolution of the electrode material in the electrolyte;

- creep and shedding of the active mass of positive electrodes due to irreversible processes of loosening and violation of uniformity.

To improve the electrical and operational characteristics of the lead-acid battery, various additives are introduced into the electrolyte or electrodes of the battery.

Known electrolyte for lead acid batteries, including sulfuric acid, nitrilotrimethylphosphonic acid, 1-hydroxyethylene diphosphonic acid, cadmium sulfate and distilled water in the following ratio of ingredients, wt. %: sulfuric acid - 0.10-50.0, nitrilotrimethylphosphonic acid - 0.001-0.1, 1-hydroxyethylene diphosphonic acid - 0.001-0.1, cadmium sulfate - 13-28, distilled water - the rest (RU, 2115198 C1, IPC Н01М 10/08, Н01М 10/22, 07/10/1998).

The closest analogue of the proposed technical solution is an electrolyte for lead acid batteries, including sulfuric acid, distilled water and an additive containing a mixture of phosphonocarboxylic acid with hydroxyalkylidendicarboxylic acid or with aminoalkylphosphonic acid with a weight content of a mixture of phosphonic acids equal to 0.004-0.015 wt. %, metal sulfate 10-18 wt. % (in terms of metal ^{n +} ) and fluorine-containing surfactants (based on perfluoroxaalkyl sulfonic acids or perfluoroxaalkylcarboxylic acids) in an amount of 0.01-0.1 wt. % relative to the weight of the whole mixture at a pH of not more than 0.8 (RU, 2267191 C1, IPC Н01М 10/08, 12/27/2005).

A disadvantage of the known electrolytes is that they slightly increase the resource and service life of the batteries. In addition, a sufficiently high concentration of sulfuric acid (up to 50 wt.%) And the presence of cadmium sulfate in the compositions enhance the electrochemical corrosion of lead gratings and down conductors.

The technical result of the invention is to improve the electrical and operational characteristics of a lead battery, as well as increasing its service life.

This result is achieved in that the electrolyte for lead acid batteries, including sulfuric acid, a phosphorus-containing compound, fluorine-containing surfactants and distilled water, additionally contains chitosan, as a phosphorus-containing compound contains methylphosphate borate, and fluorine hydrides as a fluorine-containing surface-active substance. perfluoropolyether acids with a molecular weight of 800-1000 in the following ratio of components, wt. %:

Methyl Phosphite Borate 0.6-0.8 Perfluoropolyether Acid Fluorides 0.1-0.3 Chitosan 0,1-03 Sulphuric acid 20.0-30.0 Distilled water Up to 100

A distinctive feature of the proposed technical solution is that the introduction of chitosan, perfluoropolyetheroic acid fluorides with a molecular weight of 800-1000 (PPEC) and methylphosphite borate at the stated ratio of components into the electrolyte makes it possible to obtain a synergistic effect of improving the electrical and operational characteristics of a lead battery and increase its service life in 1.5 times.

The introduction of these ingredients at different mass ratios does not allow to obtain a synergistic effect of improving the electrical and operational characteristics of a lead battery.

Methyl phosphite borate was synthesized by the reaction of 2 moles of boric acid (H ₃ BO ₃ ) with 3 moles of dimethyl phosphite (C ₂ H ₇ PO ₃ ) at a temperature of 120 ° C for 2 hours with constant distillation of methyl alcohol. Its ability to prevent lead acid corrosion in the presence of PPEC has been experimentally established.

FPEC (TU 1229-027-27992970-01) are the product of the oxidation of hexafluoropropylene with oxygen at a temperature of (-30) - (- 65) ° C in the presence of fluorine with a volume ratio of fluorine and oxygen (0.1-1.1) :( 98.9-99.9).

PPEC have high stability in aggressive environments, the ability to significantly reduce the viscosity and surface tension of aqueous solutions at various, including low (up to -40 ° C), temperatures

Chitosan (TU 9289-067-00472124-03) is an aminopolysaccharide. It is obtained by the deacetylation reaction when processing finely ground chitin with a 30-50% aqueous NaOH solution at a temperature of 110-140 ° C for 4-6 hours. The resulting product is dried and ground. It has a molecular weight of 100-120 kDa, the degree of deacetylation is 87-91%, the pH of a 1% solution of chitosan in 2% acetic acid is 3.6-3.8.

Chitosan is a high molecular weight compound that is a polyelectrolyte, so it does not increase the internal resistance of the battery. The effect of chitosan is based on its coagulating properties and increasing the viscosity of the electrolyte, which keeps the powdered active masses and reaction products on the surface of the electrodes, preventing them from slipping, shedding and leaching. Adsorbed on the surface and the tips of lead sulfate crystals, chitosan inhibits their growth.

The technology of electrolyte preparation is as follows.

The calculated quantities of distilled water according to GOST 6709-72 and methylphosphite borate are fed into a container with a stirrer, after stirring for 10-15 minutes, battery sulfuric acid is introduced according to GOST 667-73, after stirring for 15-20 minutes, chitosan and FPEC are fed in series. The resulting composition is stirred for 20-30 minutes.

The compositions of the samples of the proposed electrolyte are presented in table. 1. Examples 4 and 5 are control.

The density of the obtained electrolytes is 1.27-1.30 g / cm ³ .

To conduct comparative tests, an electrolyte was prepared according to the prototype, containing 0.02 vol. % additive consisting of a mixture of glycinebismethylphosphonic and nitrilotrimethylphosphonic acids with a weight content of the mixture of 0.01 wt. % and their ratio 1: 2, 15.0 wt. % cadmium eight-sulfate (in terms of metal) and fluorine-surfactant based on perfluoroxaalkylcarboxylic acids in an amount of 0.05 wt. % relative to the weight of the whole mixture at a pH of 0.8.

Samples of the proposed electrolyte according to examples and the electrolyte according to the prototype were poured into lead starter batteries of 6 batteries with a nominal voltage of 80 V, a nominal capacity of 250 A · h and a maximum charging current of 50 A.

Tests of storage batteries for charge safety, endurance (corrosion and cycling), as well as vibration resistance were carried out in accordance with GOST Ρ 53165-2008 "Lead-acid starter batteries for automotive vehicles. General specifications. " The standard applies to lead starter batteries used for starting internal combustion engines, lighting and powering electrical equipment using automotive vehicles (cars, buses, tractors, etc.).

The test results are presented in table. 2.

Using the proposed electrolyte in lead acid batteries will improve their electrical and operational characteristics, as well as increase battery life by 1.5 times.

Claims (1)

An electrolyte for lead acid batteries, including sulfuric acid, a phosphorus-containing compound, fluorine-containing surfactants and distilled water, characterized in that it additionally contains chitosan, as a phosphorus-containing compound contains methylphosphate borate, and as fluorine-containing surfactants - fluorosulfides with a molecular weight of 800-1000 in the following ratio of components, wt. %:
Methyl Phosphite Borate 0.6-0.8 Perfluoropolyether Acid Fluorides 0.1-0.3 Chitosan 0.1-0.3 Sulphuric acid 20.0-30.0 Distilled water Up to 100