Lithium-ion electrochemistry involves the use of lithium insertion compounds. In a lithium-ion cell, the negative electrode (anode) is graphite and the positive electrode (cathode) is a lithium-bearing metal compound. Li-ion cells have an exceptional cycling aptitude owing to the stable electrode structure: charging and discharging involves exchange of lithium ions between the electrodes via the electrolyte. Because of the high output voltage (up to 4.2 V), a non-aqueous electrolyte is used, mainly comprising a mixture of organic carbonates.
Various active materials for the positive can be used: lithium cobalt oxide, lithium nickel oxide, lithium aluminium oxide, lithium manganese oxide, or lithium iron phosphate. Saft has unparalleled experience of more than 15 years with doped nickel oxide (NCA), which offers the best cycling capability and service life, as called for in professional applications.
Saft has developed large and medium-sized batteries in cylindrical and near-prismatic shapes, with various energy-power trade-offs, from 150 W/kg with full discharge in 2 hours to 65 Wh/kg with full discharge in 15 seconds. Other remarkable properties of these products include a faradic efficiency close to 100%, long calendar life (over 20 years at ambient temperature), low self-discharge (under 5% per year), operating temperature range from –30 °C to +60 °C, and charge level gaugeable by measuring voltage.