lithium-ion battery

lithium-ion battery. A lithium-ion battery is a type of rechargeable battery that has become the dominant power source for portable electronics and electric vehicles. It operates on the principle of lithium ions moving between a negative electrode and a positive electrode during discharge and charge. Key advancements by researchers like M. Stanley Whittingham, John B. Goodenough, and Akira Yoshino led to its commercialization by Sony in 1991, revolutionizing energy storage technology.

History and development

Research into lithium batteries began in the 1970s, with M. Stanley Whittingham at Exxon proposing an early design using titanium disulfide. A pivotal breakthrough came in the 1980s when John B. Goodenough and his team at the University of Oxford discovered the lithium cobalt oxide cathode material, which offered a higher voltage. Concurrently, work on carbon-based anodes progressed, notably by Rachid Yazami. The first commercially viable, safe prototype was assembled by Akira Yoshino of Asahi Kasei, who combined the lithium cobalt oxide cathode with a petroleum coke anode. This design was successfully brought to market by Sony and Asahi Kasei for the CCD-TR1 camcorder, initiating widespread adoption. Subsequent decades saw continuous refinement, supported by research at institutions like Argonne National Laboratory and companies including Samsung SDI and LG Chem.

Principles of operation

During discharge, lithium ions de-intercalate from the anode material, typically a form of graphite, and travel through an electrolyte—often a lithium salt in an organic solvent—to the cathode, which may be composed of materials like lithium iron phosphate. This flow of ions is balanced by the flow of electrons through an external circuit, providing electrical power to a device such as an iPhone or a Tesla Model 3. During charging, an external power source applies a voltage, reversing the process and forcing the ions to migrate back to the anode. The electrolyte, a critical component developed by companies like BASF, does not conduct electrons but allows ion transport, while a separator, such as those made by Celgard, prevents physical contact between the electrodes.

Types and chemistries

Numerous cathode and anode chemistries define specific battery types, each with distinct trade-offs. Common cathode materials include layered oxides like lithium nickel manganese cobalt oxide, used by Panasonic in cells for Tesla, Inc., and polyanions like lithium iron phosphate, popularized by BYD Company and Contemporary Amperex Technology Co. Limited. Anode innovations extend beyond graphite to include lithium titanate, promoted by Toshiba, and emerging silicon-based materials. Cell configurations also vary, with prismatic formats common in BMW electric vehicles, pouch types in many Apple Inc. products, and robust cylindrical cells like the 21700 used by LG Energy Solution.

Applications

These batteries are ubiquitous in consumer electronics, powering devices from Samsung Galaxy smartphones to Dell laptops. Their high energy density is critical for the automotive industry, forming the core of powertrains for vehicles from Rivian to the Volkswagen ID.4. In aerospace, they are used in aircraft like the Boeing 787 Dreamliner and satellites from SpaceX. Large-scale installations for grid energy storage, such as those built by Fluence or Tesla Energy's Hornsdale Power Reserve, utilize them to stabilize electrical grids supplied by National Grid plc and integrate renewable sources like those from Ørsted.

Performance characteristics

Key metrics include high energy density, which enables the long runtime of a MacBook Pro, and high specific power, crucial for the acceleration of a Porsche Taycan. They exhibit a low self-discharge rate compared to older technologies like Ni-Cd. Cell voltage is typically around 3.6–3.8 volts, much higher than the 1.2 volts of a nickel–metal hydride battery. Performance can degrade over hundreds to thousands of charge-discharge cycles, influenced by factors like operating temperature, a critical parameter managed by the battery management system in a Chevrolet Bolt.

Safety and environmental impact

Safety risks primarily involve thermal runaway, which can be triggered by internal short circuits, overcharging, or physical damage, as witnessed in incidents with the Samsung Galaxy Note 7. Mitigation strategies include sophisticated battery management system electronics, robust cell design from manufacturers like Murata Manufacturing, and the use of safer electrolytes. Environmental concerns focus on the mining of raw materials like cobalt from regions such as the Democratic Republic of the Congo, and the challenges of recycling. Organizations like the United States Department of Energy and companies including Redwood Materials are developing closed-loop recycling processes to recover valuable metals like nickel and lithium. Category:Electric batteries Category:Lithium-ion batteries Category:Energy storage