First proposed in the 1970s and produced commercially by Sony in 1991, lithium batteries are now used in mobile phones, airplanes and cars. Despite several advantages which have lead them to increasing success in the energy industry, lithium ion batteries have some drawbacks and are a topic that elicits much discussion. But what exactly are lithium batteries and how do they work? What are lithium batteries made of? A lithium battery is formed of four key components. It has the cathode, which determines the capacity and voltage of the battery and is the source of the lithium ions. The anode enables the electric current to flow through an external circuit and when the battery is charged, lithium ions are stored in the anode. The electrolyte is formed of lithium salts, solvents and additives, and serves as the conduit of lithium ions between the cathode and anode. Finally there is the separator, the physical barrier that keeps the cathode and anode apart. Pros and cons of lithium batteries Lithium batteries have a much higher energy density than other batteries. They can have up to 150 watt-hours (WH) of energy per kilogram (kg), compared to nickel-metal hydride batteries at 60-70WH/kg and lead acid ones at 25WH/kg. They also have a lower discharge rate than others, losing around 5% of their charge in a month compared to a nickel-cadmium (NiMH) batteries which lose 20% in a month. However, lithium batteries also contain a flammable electrolyte that can cause small scale battery fires. It was this that caused the infamous Samsung Note 7 smartphone combustions, which forced Samsung to scrap production and lose $26bn in market value. It should be noted that this has not happened to large scale lithium batteries. Lithium-ion batteries are also more expensive to produce, as they can cost nearly 40% more to produce than nickel-cadmium batteries. Cesium is an element. In its natural state, cesium salts is not radioactive. However, it can be made radioactive in the laboratory. People use both forms of cesium for medicine. Despite serious safety concerns, non-radioactive cesium is taken by mouth for treating cancer. This is sometimes called “high pH therapy.” According to people who promote high pH therapy, taking cesium chloride by mouth reduces the acidity of tumor cells (raises their pH), which are described as very acidic. But these claims are not supported by science. There is no scientific research that indicates tumor cells differ in pH from normal cells or that cesium affects the pH of tumor or normal cells. Non-radioactive cesium is also used to treat depression. Healthcare providers sometimes treat cancer patients with radioactive cesium (cesium-137). In industry, radioactive cesium is also used in instruments that measure thickness, moisture, and liquid flow. How does it work? There isn't enough information to know how cesium might work. Some people who promote “high pH therapy” say cesium affects the pH (acidity) of cancer cells, but there's no scientific research to support this claim. Rubidium is a silvery-white and very soft metal — and one of the most highly reactive elements on the periodic table. Rubidium has a density about one and a half times that of water and is solid at room temperature, although the metal will melt if it's just a bit warmer, according to Chemicool.  Like the other alkali metals (lithium, sodium, potassium, cesium and francium), rubidium reacts violently with water, oxidizes when reacting with oxygen, and ignites due to humidity in the air, so great care must be taken when working with the element. Scientists treat rubidium salts as a toxic element, according to Encyclopedia, although no known health effects of rubidium are known. History Rubidium was discovered by German chemists Gustav Robert Kirchhoff and Robert Wilhelm Bunsen in 1861 when they were observing the spectrum of the mineral lepidolite as it burned, according to Peter van der Krogt, a Dutch historian. The spectrum of rubidium showed off two dark red lines, and the scientists named the newly discovered alkali metal rubidium after the Latin word for “deep red.”  According to Chemicool, rubidium was extracted from the surrounding mineral by electrolysis. Approximately 330 lbs. (150 kilograms) of the lepidolite ore was needed in order to extract enough rubidium (about 1.5 percent of the mineral) in order to study its properties. The scientists found that rubidium was more electropositive (meaning that rubidium tended to form positive ions more readily, according to Encyclopedia) than potassium, another alkali metal and reacted violently with water releasing hydrogen.