that lithium ion batteries are small, lightweight, high-capacity and extremely effective?
Why are lithium ion batteries currently on everyone's lips?
Small, lightweight and, above all, mobile pieces of equipment are becoming more and more popular. This includes mobile phones, notebooks and, for some time now, even garden tools. They all need power, but even in the case of garden tools power cables are increasingly seen as cumbersome. Consequently, high-capacity, reliable batteries are becoming more and more important. Modern lithium ion batteries have also recently become established as a power source for garden tools. Their particular advantage: They are not subject to the disruptive memory effect of previous generations of batteries and are therefore ready to use at any time. But how does this compact battery, which also has a low self-discharge rate, work?
How do lithium ion batteries work?
As its name suggests, the lithium ion battery is a rechargeable battery based on the light alloy lithium. Unlike lithium batteries, these batteries are rechargeable. They contain a combination of sensitive chemical components with different electrical charges which can react extremely quickly. The positively and negatively charged chemicals are separated only by a wafer-thin plastic wall.
Lithium ion batteries are also called swing, shuttle or ion transfer batteries. These descriptions reflect the basic principle of this type of battery: The charging and discharging process essentially only causes a transfer of lithium ions, i.e. the electrically charged lithium atoms, between the two electrodes. When the battery is charging, the lithium ions are transferred to a graphite layer which is made of carbon. During discharging, the ions migrate back. The migration of the ions generates an electromagnetic force which controls the flow of the electrons. In lithium ion batteries, the positive terminal is made of lithium metal oxide and the negative terminal is made of carbon.
What does "memory effect" mean?
The capacity of a lithium ion battery reduces over time even if it is not used, mainly due to the exploitative reaction of the lithium with the electrolytes. This process is known as self-discharging. It happens in all types of batteries, but is significantly less in lithium ions batteries than in older types.
There is no memory effect in the case of lithium ion batteries. In old nickel cadmium batteries (NiCd), frequent partial discharging led to the battery 'noticing' the energy requirement needed for recharging and no longer making its full capacity available. Lithium ion batteries on the other hand can be recharged to their full capacity at any time and have a low self-discharge rate. This makes them easy to handle, and in spite of their high capacity they are small and lightweight. Moreover, they are now also available in higher performance classes at affordable prices, thus allowing them to be used in larger pieces of equipment with a high energy requirement.
Why is it that such good technology is only available now?
Although lithium ion batteries were known in theory at the beginning of the 20th century, it was not possible to use them for a long time. The advantages of lithium as an electrode material were known previously and a lithium sulphur dioxide battery was available in 1938 and a lithium-thionyl chloride battery in 1969. Lithium ion batteries, however, still reacted extremely sensitively to incorrect handling and were therefore not suitable for everyday use. However, in 1995 the first lithium ion battery was launched onto the market by Sony. Today, the chemical processes in the battery are controlled by a battery management and monitoring system (BMS). This protects against deep discharge, overcharging and thermal overload. In addition to the complex charging system, lithium ion batteries have a particularly pressure-resistant housing, which makes them approximately 30% more expensive than nickel metal hydride (NiMH) batteries.