Lithium ion cell (Lilon/Li polymer)
Lithium-ion battery technology is currently used in a large range of applications, both for consumer market and industrial applications:
- Electronic devices such as mobile phones, laptops and tablets
- Power Tools
- Hybrid-Electric Vehicles
- Electric Vehicles
- Large renewable energy power stations
- Supply of ancillary services to the electrical grid
Rechargeable Lithium-Ion batteries are primarily found in market segments where their high energy and power density as well as their superior cycling ability create value. Li-ion batteries are the product of choice for electric and hybrid vehicles in which both these criteria are important. They are also the electrical energy storage technology of choice for large renewable energy farms in which smoothing functions are required along with ancillary services to the network (frequency regulation, primary power regulation), as both these requirements place a high demand on the battery cycling ability.
Lithium-ion batteries are also the reference technology for plug-in and full-battery electric vehicles (PHEVs and BEVs) of the coming years. While other types of batteries, including lead-acid and nickel-metal hydride (in the first generation of the Toyota Prius hybrid) will continue to retain considerable market share in the short term, lithium-ion batteries are expected to dominate the market by 2017 (Deutsche Bank, 2009). Compared with other relevant battery types, lithium-ion batteries have the highest energy density. Their cost is rapidly decreasing.
Significant further improvements of the technology are expected in the coming years, since the status of maturity of the Li-Li-ion is considered in the mid of the classical “S shape” curve of development.
Chemistry and technology
The Li-ion technology includes several chemistries:
All Lithium-ion technologies are based on the same principle: Lithium ions are stored in the anode (or negative electrode), and transported during the discharge to the cathode (or positive electrode) in an organic electrolyte. The most popular materials are the graphite for the anode, and a metal oxide for the most cathode, based on Nickel, Manganese and Cobalt. All of these materials have good Lithium insertion or intercalation properties, allowing the large amount of energy storage.
Nevertheless, several oxides types, and several cathodes types can be used, providing significantly different performances to the batteries.
|Full name||Lithium Cobalt Oxide||Lithium Nickel Oxide||Lithium Nickel Cobalt Aluminium Oxide||Lihium Nickel, Manganese Cobalt Oxide||Lithium Manganese Spinel||Lithium Iron Phosphate||Lithium Titanate|
|LiMn2O4||LiFePO4||e.g.: LMO, NCA, …|
|Cell voltage||3,7 - 3,9V||3,6V||3,65V||3,8 - 4,0V||4,0V||3,3V||2,3 – 2,5V|
Source:Daimler analysis, Nationale Plattform Eletromobilität, 2010.
The selection of a battery technology depends on the application requirements regarding performance, life, safety and cost, with each battery type providing specific functionalities. The battery technology is generally characterized by type of cell format. Main types of cell format used for the Li-ion batteries are the following:
- hard case cylindrical or prismatic : these cells are generally having an Aluminium can with laser-welded or crimped cover. They contains liquid electrolyte.
- Soft case or « pouch cells »: these cells are using a thin aluminized plastic as a bag, glued with different type of polymers for the tightness. In general, they contains electrolyte in a polymer, reason why they are often called “lithium-ion polymer”.
The cells are assembled to forms battery packs and batteries, embedded in hard casing with electro-technical and electronic management systems (BMS). The battery pack format and voltage is independent of the cell type, as shown in the graph of E-mobility battery sizes below. The functional risk associated with batteries is the electrical risk (safety regulations changes above 60V).