In a Li-ion battery the cathode is a lithiated metal oxide and the anode is made of layers of graphitic carbon. The electrolyte is made up of lithium salts dissolved in organic carbonates. When the battery is being charged lithium ions move out of the cathode and into the electrolyte solution where they are free to move to the negative electrode. At the carbon anode they combine with external electrons and are deposited between carbon layers as lithium atoms. This process is reversed during discharge.
The main advantages of Li-ion batteries, compared to other advanced batteries, are—
Sony introduced Li-ion batteries in the early 1990s. In just a few years they took over 50% of the small portable market and today dominate the consumer electronic market. Nevertheless, a number of challenges remain for large-scale Li-ion batteries. The main hurdle is the relatively high cost due to special packaging, internal overcharge protection circuits, and thermal management considerations. Several companies are working to reduce manufacturing costs in order to capture large energy markets (multi-kW, multi-kWh sizes for residential and small commercial use). Safety is also a concern, but companies are developing alternate chemistries that moderate the safety concerns, although sometimes at a cost to performance.
Updated April 2010