Lithium Batteries
The fastest growing use of lithium over the last eight years has been in the lithium-ion battery market. In 2008, the lithium-ion battery market was the second largest consumer of Lithium and accounted for 20% of lithium consumption.
The emerging application of lithium for batteries used as the power source for hybrid electric (HEVs), plug-in hybrid electric (PHEVs) and electric vehicles (EVs) could provide a further substantial source of future demand for the metal.
Electric vehicles can be grouped into three main categories:
- HEVs: whose power-train is a combination of electric power and gasoline engine. HEVs come in two variants: (i) the mild HEV uses a battery pack to supplement the gasoline engine either during acceleration, when the vehicle is at rest or low speed driving, and (ii) the full HEV allows the car to be propelled in full electric mode and the batteries are recharged by regenerative braking. HEVs consume approximately 0.5 kg Li per vehicle.
- PHEVs: which allow batteries to be recharged by plugging the vehicle into the electric mains system. PHEVs consume approximately 1.8-4.2 kg Li per vehicle.
- EVs: fully electric vehicles whose main propulsion mode is electric, but which may also have a small gasoline engine to either assist in recharging the batteries or provide power to the engine if the battery charge is depleted. EVs consume approximately 10 kg Li per vehicle.
Given the increasing political and consumer focus on climate
change, car producers are looking for ways to lower both carbon
emissions and fuel consumption in transport applications. HEVs have
been on the market for a number of years, with annual sales in the
United States of America increasing from approximately 20,000 in
2000 to almost 350,000 in 2007. To date, most mass produced HEVs
have incorporated nickel metal hydride (NiMH) batteries, although
many automobile manufacturers are now starting to develop EVs
incorporating the lithium-ion battery as the electrical power
source for their vehicles.
There are a number of parameters on which battery technologies are compared, with the key parameters being specific energy density and specific power density. Specific energy density is a measure of the amount of energy that can be stored by a battery in comparison to its weight. Specific power density compares the rate at which energy is delivered relative to the weight of the battery, which is related to the acceleration and top speed of a particular vehicle. The faster the delivery of energy, the quicker a vehicle can get to top speed.
Lithium-ion batteries are optimised for high specific energy density and are the only battery technology that can achieve the energy storage capacity required to match the performance of traditional fuel vehicles, without excessive weight compromising vehicle performance. Consequently, the demand for lithium is expected to increase as vehicle electrification moves toward full EVs from HEVs and PHEVs.
