Carbon battery, also known as zinc carbon battery, is a new type of battery invented by Carl Gassner in 1886. Before that, the batteries that people usually used were fragile glass shells, because the electrolyte was liquid acid, and any metal shell was easy to corrode. The emergence of carbon battery has changed the whole battery industry. It provides reliable power support for the emergence and wide application of portable electronic equipment, and it has been popular for nearly half a century. Therefore, this article will introduce zinc carbon battery in some detail.
What is carbon battery
Zinc carbon battery is a kind of dry battery and primary battery. Its power generation is mainly generated by the chemical reaction between positive manganese dioxide and negative zinc metal, which can provide about 1.5 V direct current. The main elements of zinc carbon battery are as follows:
·Positive electrode: manganese dioxide and a carbon rod in the center of the battery surrounded by manganese dioxide.
·Negative electrode: zinc metal, which is used as battery case and negative terminal. Zinc in the negative electrode is easy to produce adverse side effects, which will lead to the increase of battery self discharge and battery corrosion. Therefore, in the past, the manufacturers would coat mercury on the surface of zinc metal to form amalgam to protect zinc metal. Since mercury is highly toxic, modern batteries will not use this method. Modern manufacturers will choose high-purity zinc metal to prevent corrosion and self discharge.
·Separator: in the early stage, a layer of starch or flour was used as the separator of zinc carbon battery. In modern times, a layer of extremely thin starch layer paper was mainly used, so the battery can carry more manganese dioxide.
·Electrolyte: ammonium chloride paste, compared with liquid ammonium chloride, solid ammonium chloride electrolyte can provide longer service life and more stable voltage for the battery. Its composition is mainly composed of 26% ammonium chloride, 65.2% water, 8.8% zinc chloride and 1% corrosion inhibitor.
·In the early days, zinc carbon battery is sealed with a layer of asphalt to prevent the electrolyte from drying. In modern times, thermoplastic gasket sealant is used to deal with it.
In the 19th century, because of its large discharge capacity, small volume, low self discharge rate and strong shell, zinc carbon battery became the first commercial dry battery. The emergence and commercialization of zinc carbon battery has also led to the popularity of small portable devices. The emergence of flashlight is also attributed to zinc carbon battery.
How does a carbon battery work
Any battery power generation depends on the chemical reaction between the positive and negative materials to generate electric charge, so does the zinc carbon battery. The power generation of zinc carbon battery is through the reaction of manganese dioxide on the positive electrode and zinc metal on the negative electrode. The total chemical equation of the reaction is: Zn + 2mno2 → ZnO + Mn2O3. However, the actual reaction is much more complicated. Due to the existence of ammonium ion, the electrolyte will generate ammonia and hydrogen under the action of charge. These two gases will react with zinc chloride in the electrolyte and manganese dioxide in the positive electrode respectively. Without these reactions, the battery may swell or leak.
And the carbon rod in the center of the battery is mainly used to collect current and provide stable structural support for the battery. The raw material of carbon rod is very porous. In order to prevent water loss and oxygen from entering the negative electrode to corrode zinc metal, it must be treated with wax or oil. However, enough porosity must be maintained during the treatment, because carbon rod is also used to release hydrogen generated by reaction.
It is worth noticing that the negative electrode of zinc carbon battery is composed of zinc metal. Zinc metal is not only present in the negative electrode as a discharge reaction material, but also the shell of the negative electrode of the battery. This means that once it receives a large degree of wear in use, the capacity and normal use of the battery will be adversely affected.
Why is carbon used in battery
Although carbon zinc battery has been eliminated for a long time because of its low discharge efficiency, low capacitance, pollution and unable to charge, carbon based materials have been active in the field of battery. This is because carbon based materials have good electrical conductivity, stable chemical properties and low cost. Carbon plays an important role in the field of electricity consumption, and its application is also extensive:
·Carbon materials can be added to the electrode as additives to improve the conductivity of the electrode.
·Carbon can also be used as a catalyst for electrochemical reactions or as a base material for electrocatalysts.
·Carbonaceous materials can be made into solid structures for bipolar separators or current collectors.
In addition, graphite carbon has been widely used in modern electrochemical technology. This kind of carbon has a hexagonal structure, and the carbon atoms are arranged orderly on the layer planes. The modern production of lithium batteries and fuel cells, graphite carbon and carbon containing materials are their important raw materials. Moreover, there is no suitable substitute for carbon materials at present. Most of the new materials developed can not have the advantages of low cost, high conductivity and strong chemical stability. It can be said that if there is no carbon in the production and use of batteries, the current batteries may not only have higher cost, but also have lower performance.
Although zinc carbon battery has been eliminated for a long time, carbon materials have always affected the production and use of batteries for hundreds of years. In a word, the appearance of carbon battery is a memorable change in the history of battery technology. Hope you can find this article helpful.
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