Lithium-Ion batteries: What you should know!

2024/07/31 – Following the systematic naming of inventors like the Otto engine and the Diesel engine, the lithium-ion battery should actually be called the Yoshino battery. This is because Dr. Akira Yoshino further developed the first functional lithium-ion battery in the early 1980s, making it commercially viable by 1985. He benefited from the preliminary work of British scientist Stanley Whittingham and American John B. Goodenough. The significance of the invention is highlighted by the Chemistry Nobel Prize awarded to the trio in 2019 for their achievements.

Beginnings in the 1970s

Research on lithium batteries began in the 1970s at the Technical University of Munich. During the same decade, physicist Stanley Whittingham at the University of Oxford combined a titanium disulfide cathode with a metallic lithium anode in a battery, achieving a cell voltage of about 2 volts. In the early 1980s, John B. Goodenough at the University of Texas in Austin experimented with lithium cobalt oxide as a cathode, leading to higher voltage and greater safety.

In the mid-1980s, Akira Yoshino, a chemist and engineer at Asahi Kasei, further developed the battery's anode, replacing the highly reactive metallic lithium with carbonaceous material (graphite). This established the fundamental structure for the first lithium-ion cell and advanced the technology to commercialize it by 1985.

The Functionality

A lithium-ion cell comprises many individual parts, with various cell types differing in details. Below, we describe the components and functionality of a lithium-nickel-manganese-cobalt-oxide cell:

Like any battery, lithium-ion batteries convert chemical energy into electrical energy, available as electricity.

In each cell of the battery, one electrode interacts with another electrode (its counter-electrode). One electrode is positively charged (cathode), and the other is negatively charged (anode). When the battery operates and the circuit is closed by connecting a load – e.g., a light bulb – it discharges. Electrons flow from the anode to the cathode. The charge exchange through the conductive electrolyte from one half-cell to the other generates electricity. When charging the battery, the same process occurs in the opposite direction.

Structure of the Lithium-Ion Battery

The cathode of the lithium-ion battery consists of a lithium metal oxide containing varying amounts of nickel, manganese, and cobalt. The lithium is covalently bonded in this crystal – meaning the atoms are held together in a molecularly structured chemical compound.

The anode is usually made of graphite, which consists of countless layers of carbon, called graphene. The lithium ions are "intercalated," meaning the ions are electrostatically stored between the individual crystal lattice planes while maintaining their structure.

An electrolyte is contained in the cell to allow the lithium ions to move as charge carriers. This is typically based on an organic solvent. The addition of lithium salts increases ion conductivity.

To avoid short circuits, a separator is installed between the electrodes. It consists of microporous plastic, comparable to nonwoven fabrics. The separator is permeable to lithium ions but simultaneously prevents direct contact between the anode and cathode, which would lead to a short circuit.

Advantages of Lithium-Ion Batteries

Lithium-ion batteries are characterized by high cycle stability (the number of charges and discharges) and, compared to other chemical energy storage devices, high energy density and low self-discharge. Their specific structure and materials ensure high performance, which remains almost constant even during extended operation. A lithium-ion battery loses only one to two percent of its capacity per month when not in use.

Partial charges are possible at any time with these batteries. Lithium-ion batteries can also provide particularly high currents, making them suitable for very energy-intensive consumers such as electric cars. Additionally, they are ideal as energy storage for renewable energies (like solar or wind power), efficiently storing unused energy and releasing it when needed.