Rechargeable batteries
All battery cells are based on the principle that chemical energy is converted into electrical energy. The big difference between rechargeable (secondary) and non-rechargeable (primary) batteries is that the former is designed to safely recharge.
Properly maintained, a rechargeable cell can be reused several hundred times. By applying a certain current or voltage, the cell will be charged. The size of the stream determines how long a charge takes. The applied current in the form of electrical energy is thereby converted into chemical energy at the electrodes. When electrical energy is needed from the battery cell, new chemical energy is converted into electrical energy from the electrodes to the external application.
Due to the ever-increasing market of power-consuming appliances, rechargeable batteries have become increasingly common use in, for example, portable equipment such as mobile phones, cameras, laptops, vacuum cleaners, shavers, electric toothbrushes and various hand tools. A large number of different types of rechargeable batteries are also used in industry, healthcare, and military applications. In recent years, rechargeable batteries, especially lithium-ion batteries, have made a major entry into the automotive industry in an effort to electrify the transport sector.
Form Factors
Rechargeable batteries are available in all possible form factors from cylindrical and prismatic (rectangular) to so-called pouch cells of various sizes. Nickel-metal hydride batteries (NiMH), which have a voltage of 1.2 V, are commonly found in form factors that correspond to those of the alkaline batteries (eg cylindrical AA and AAA) because the voltage is similar and therefore can be used as a direct substitute for these batteries.
Nickel-cadmium batteries (NiCd) occur in a similar form factor as NiMH. Lithium-ion batteries, on the other hand, usually do not appear in the same format as alkaline batteries to avoid misuse of them in equipment that cannot withstand the higher voltage of lithium-ion batteries, ie> 3 volts. Instead, the most common cylindrical cell size is a slightly larger variant of the AA format that goes by the term 18650 (18 mm in diameter and 65 mm high).
Classification into chemical systems and typical applications:
Lithium-Ion Batteries (Li-ion)
The launch of lithium-ion batteries in the 1990s paved the way for the development of a plethora of portable electronic devices, e.g. mobile phones and laptops, where the need for small and light batteries with high energy density is of great importance.
Nowadays, lithium-ion batteries clearly dominate the market for portable equipment batteries. The batteries are used in e.g. mobile phones, hand tools, and medical technology products, but also in larger applications such as passenger cars and heavy vehicles as well as stationary energy stores.
The majority of the production of lithium-ion cells is today in Asia (mainly China). In Europe, it is planned to start a number of large-scale cell manufacturing factories in the 2020s. Gigafactories to increase competition and shorten the transport of battery cells to companies with production in Europe.
Nickel-Metal Hydride Batteries (NiMH)
The NiMH battery has a high energy density and provides more than twice the operating time compared to the corresponding NiCd type. NiMH batteries became both a technical and environmental alternative for the replacement of NiCd batteries. Today, however, much of the market where NiMH batteries were previously used has switched to using lithium-ion batteries because they have even higher energy density than NiMH batteries. NiMH batteries were the technology used by Toyota in the first versions of its popular hybrid Toyota Prius.
Nickel-cadmium batteries (NiCd)
The positive properties of the NiCd battery in being able to handle large discharge currents, operate in a large temperature range and be robust have historically been one of the dominant rechargeable batteries for the supply of portable and stationary equipment for the most diverse applications.
In line with the introduction of the lithium-ion battery in the market and improvements in the NiMH battery, the NiCd batteries are almost completely out of competition today. A major contributing factor to this is also that NiCd batteries contain the environmentally hazardous metal cadmium and the batteries are now prohibited for use in consumer products within the EU and many other countries in the world. However, some users remain, such as power supply for medical devices, alarm systems, and various military applications.
Valve controlled lead-acid batteries
The main area of use for closed (valve controlled) lead batteries is for power supply of large electrical equipment, off-grid systems and where large amounts of energy are required but where the cost must not be too great.
