An alkaline battery (IEC code: L) is a type of primary battery where the electrolyte (most commonly potassium hydroxide) has a pH value above 7. Typically, these batteries derive energy from the reaction between zinc metal and manganese dioxide.
Compared with zinc–carbon batteries, alkaline batteries have a higher energy density and longer shelf life yet provide the same voltage.
A zinc–carbon battery (or carbon zinc battery in U.S. English) is the generic “heavy duty” disposable battery. It has been overtaken in recent times by the longer-lasting alkaline battery.
A zinc–carbon battery is a dry cell that provides direct electric current from the electrochemical reaction between zinc (Zn) and manganese dioxide (MnO2) in the presence of an ammonium chloride (NH4Cl) electrolyte. It produces a voltage of about 1.5 volts between the zinc anode, which is typically constructed as a cylindrical container for the battery cell, and a carbon rod surrounded by a compound with a higher Standard electrode potential (positive polarity), known as the cathode, that collects the current from the manganese dioxide electrode. The name "zinc–carbon" is slightly misleading as it implies that carbon is acting as the oxidizing agent rather than the manganese dioxide.
An electric battery is a source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices. When a battery is supplying power, its positive terminal is the cathode and its negative terminal is the anode. The terminal marked negative is the source of electrons. When a battery is connected to an external electric load, those negatively charged electrons flow through the circuit and reach the positive terminal, thus causing a redox reaction by attracting positively charged ions, or cations. Thus, higher energy reactants are converted to lower energy products, and the free-energy difference is delivered to the external circuit as electrical energy. Historically the term "battery" specifically referred to a device composed of multiple cells; however, the usage has evolved to include devices composed of a single cell.
Primary (single-use or "disposable") batteries are used once and discarded, as the electrode materials are irreversibly changed during discharge; a common example is the alkaline battery used for flashlights and a multitude of portable electronic devices. Secondary (rechargeable) batteries can be discharged and recharged multiple times using an applied electric current; the original composition of the electrodes can be restored by reverse current. Examples include the lead–acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and mobile phones.
View the full Wikipedia page for Battery (electricity)Potassium carbonate is the inorganic compound with the formula K2CO3. It is a white salt, which is soluble in water and forms a strongly alkaline solution. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is used in production of dutch process cocoa powder, production of soap and production of glass. Commonly, it can be found as the result of leakage of alkaline batteries. Potassium carbonate is a potassium salt of carbonic acid. This salt consists of potassium cations K and carbonate anions CO2−3, and is therefore an alkali metal carbonate.
View the full Wikipedia page for Potassium carbonateManganese dioxide is the inorganic compound with the formula MnO
2. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO
2 is for dry-cell batteries, such as the alkaline battery and the zinc–carbon battery, although it is also used for other battery chemistries such as aqueous zinc-ion batteries. MnO
2 is also used as a pigment and as a precursor to other manganese compounds, such as potassium permanganate (KMnO4). It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO
2 has an α-polymorph that can incorporate a variety of atoms (as well as water molecules) in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in α-MnO
2 as a possible cathode for lithium-ion batteries.
A nickel–metal hydride battery (NiMH or Ni–MH) is a type of rechargeable battery. The chemical reaction at the positive electrode is similar to that of the older nickel–cadmium cell (NiCd), with both using nickel oxide hydroxide, NiO(OH). However, the negative electrodes use a hydrogen-absorbing alloy instead of cadmium. NiMH batteries typically have two to three times the capacity of NiCd batteries of the same size, with significantly higher energy density, although only about half that of lithium-ion batteries. NiMH batteries have almost entirely replaced NiCd.
These batteries are typically used as a substitute for similarly shaped non-rechargeable alkaline and other primary batteries. They provide a cell voltage of about 1.2V while fresh alkaline cells provide 1.5V; however devices designed for alkaline batteries operate until cell voltage gradually drops to around 1.0V, while the voltage of a fully-charged NiMH cell drops more slowly, giving good endurance for a 1.0V end point. NiMH batteries are less prone to leaking corrosive electrolyte than primary batteries.
View the full Wikipedia page for Nickel–metal hydride battery