Why alkaline zinc-manganese batteries perform better than ordinary zinc-manganese batteries

Zinc-manganese batteries can be divided into ordinary zinc-manganese batteries and alkaline zinc-manganese batteries.

Ordinary zinc-manganese battery: the positive electrode is a graphite rod and manganese dioxide (MnO2), the negative electrode material is a zinc plate, and the electrolyte is a starch paste of ammonium chloride (NH4Cl) and zinc chloride (ZnCl2). Since the positive electrode has a graphite rod, a common zinc-manganese battery is sometimes called a carbon battery.

Alkaline Zn-Mn battery: The positive electrode is manganese dioxide, the negative electrode is zinc, and the electrolyte is more common with potassium hydride (KOH). Alkaline batteries can be said to be upgraded products of ordinary zinc-manganese batteries.

The overall performance of alkaline zinc-manganese batteries is higher than ordinary zinc-manganese batteries:

The capacity of alkaline batteries is significantly higher than that of ordinary batteries, about 3-8 times that of the latter;

The discharge capacity of alkaline batteries is significantly higher than that of ordinary batteries, and is more suitable for large current discharge;

The storage period of alkaline batteries can reach 3-7 years, which is 3-7 times that of ordinary batteries;

The utilization rate of raw materials for alkaline batteries is higher, such as zinc utilization rate is 3-8 times that of ordinary batteries.

Therefore, alkaline zinc-manganese batteries are better than ordinary zinc-manganese batteries.

The alkaline zinc-manganese battery is a battery made of a reverse polarity structure in which zinc is used as a negative electrode, manganese dioxide is used as a positive electrode, and sodium hydroxide or potassium hydroxide is used as an electrolyte. [1]

Introduction

Zinc is used as the negative electrode, manganese dioxide is the positive electrode, and potassium hydroxide solution is the primary battery of the electrolyte referred to as alkaline manganese battery, commonly known as alkaline battery. Its product line is indicated by the letter "LR", and the number after it indicates the model number of the battery.

The alkaline manganese battery that was first seen in the German patent is a wet battery. In 1912, another dry battery obtained a German patent. It was not until 1949 that the "Crown" type battery of Yuehua Company of the United States was put on the market. After the successful development of the cylindrical structure in 1960, the alkaline manganese battery was rapidly developed.

Alkaline Zn-Mn battery is an upgraded high-performance battery product for ordinary dry batteries. It has LR6 (No. 5) and LR03 (No. 7) batteries. The products are divided into common type (containing 0.60% of mercury) and micro-mercury (containing less than 0.025% of mercury), and trial production of mercury-free batteries is currently underway.

Electrode reaction

Button Battery:

Negative reaction: Zn+2OH--2e-=Zn(OH)2

Positive electrode reaction: 2MnO2+2H2O+2e-=2MnOOH+2OH-

Total reaction: Zn+2MnO2+H2O=Zn(OH)2+Mn2O3

General battery:

Negative electrode reaction: Zn+2OH-=Zn(OH)2+2e-, Zn(OH)2+2OH-=[Zn(OH)4]2-

Positive electrode reaction: MnO2+H2O+e-=MnOOH+OH-, MnOOH+H2O+e-=Mn(OH)2+OH-

Total reaction: Zn+MnO2+2H2O+2OH-=Mn(OH)2+[Zn(OH)4]2-

(1) Cylindrical battery structure

The alkaline zinc-manganese battery is representative of a cylindrical type, which is opposite to the structural layout of a cylindrical ordinary zinc-manganese battery. In the alkaline zinc-manganese battery, the annular positive electrode is next to the inner wall of the container steel cylinder, and the negative electrode is located in the middle of the positive electrode. There is a nail-shaped negative current collector, which is welded on the top cover as the negative pole of the battery, and the steel cylinder is positive electrode. In order to facilitate and can be used interchangeably with ordinary zinc-manganese batteries, and avoid the mistakes of the positive and negative electrodes when using the batteries, the semi-finished products of the above alkaline zinc-manganese batteries are inverted when the battery is designed and manufactured, so that the bottom of the steel cylinder faces upwards, and the opening faces toward Next, put a convex cover (fake cover) on the bottom of the steel cylinder, the positive pole is located above; a metal piece (false bottom) is welded on the negative electrode lead body, so that the appearance of the alkaline zinc-manganese battery is positive and negative. And the shape is consistent with ordinary zinc-manganese batteries.

(2) Rolled battery structure

The structure adopts a metal mesh as a carrier, and the positive and negative electrodes are respectively pressed into a thin strip shape, and then stacked with a diaphragm to be wound into a spiral (capacitive) structure battery, and the structure is characterized in that the positive and negative electrodes have a large area of action. The overpotential is small, so that higher capacity can be obtained at low temperature and large current discharge.

(3) Square type cell structure

The positive and negative electrodes of the square type battery adopt a pole group structure, and the positive and negative electrodes are respectively pressed into a square-shaped sheet, and a metal current collecting net is sandwiched between the pole pieces.

Production Method

The most popular alkaline manganese batteries are available in cylindrical and button shapes, as well as square and flat shapes. The outer casing of the cylindrical battery (see figure) is a nickel-plated steel casing with a positive cap, which doubles as a positive current collector. Close contact with the shell is the use of electrolytic oxidizing, graphite

Alkaline zinc-manganese battery

Alkaline zinc-manganese battery

A positive electrode ring (cathode) made of carbon black. The middle is filled with a zinc paste prepared by zinc powder and gel lye, that is, a negative electrode (anode) having a brass current collector interposed therein. The positive and negative electrodes are separated by an alkali-resistant pipette. The negative current collector is welded to the negative electrode cap and inserted into the plastic sealing ring. The assembly is inserted into a steel shell and crimped and sealed, and the steel shell is wrapped with a heat shrinkable film trademark to become a commercial battery. The structure and size specifications of the button alkaline manganese battery are basically the same as those of the zinc-silver button battery. Typical formula (mass) of active materials in the battery: positive electrode is electrolytic manganese dioxide 90-92%, graphite powder 8-9%, acetylene black black 0.5-1%; negative electrode is amalgam zinc powder 88-90%, zinc oxide 5 to 7%, CMC sodium salt 3 to 4%, KOH solution (plus) appropriate amount. The electrolyte is a solution of 8 to 12 N KOH in which an appropriate amount of zinc oxide is dissolved.

Performance characteristics

The alkaline manganese battery has a nominal voltage of 1.5V and a maximum voltage of 1.65V. Its discharge performance has the following characteristics compared with ordinary zinc-manganese batteries: 1 small internal resistance, continuous operation under heavy load while maintaining high stability Voltage; 2MnO2 utilization rate is high, compared with the same volume, its charge is about twice as large as that of cardboard battery; 3 self-discharge rate is small during storage, and it can still maintain 85% of original charge after 3 years of storage, and has a long life. 4 low temperature performance, can output 25% of normal temperature charge at -20 °C, can work at lower temperature under light load; 5 can be used as cheap battery under specific design and strictly controlled use conditions Repeated use of multiple charges. MnO2 is doped with titanium or some other metal oxide to improve the charging performance of MnO2.

Variety specifications and uses

The specifications of the main varieties of commonly used cylindrical alkaline manganese batteries are shown in the table. The button-type alkaline manganese battery has a charge of about 55% of the same size zinc-silver button battery. Commonly used models are LR41, LR43, LR44, LR54 and LR55, and their size specifications are the same as their corresponding zinc-silver button batteries.

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