Lithium-ion batteries (Li-ion) are a type of rechargeable battery in which lithium ions shift from the a negative electrode to a positive electrode when discharging and in the reverse when charging.
Li-ion batteries are very common in small electrical appliances like mobile phones and lap top computers, they have a high energy density ratio for their size, a low self discharge rate, no battery memory effect and a much longer life cycle.
In recent times Lithium-ion batteries have begun to replace the traditional flooded deep cycle lead-acid batteries commonly used in off grid energy storage systems storing electricity generated from solar panels and wind turbines. With lithium-ion battery technology constantly evolving, the lithium-cobalt-oxide cathode remains the vital component in most Li-on batteries.
In the 1970’s Stan Whittingham a chemist at Stanford University made an electrode that could store lithium ions within layers of titanium sulfide in a way that could be rechargeable. These early experimental batteries were unstable and sometimes exploded.
Later on in 1980 a cobalt-oxide cathode was developed by John Bannister Goodenough enabling a much higher storage capacity of up to three times that of any existing room temperature battery of the time, the result was that much smaller batteries could be made.
Why are Lithium-ion batteries better for residential solar energy storage?
Lithium-ion batteries have many advantages over deep cycle lead-acid batteries with a much higher power to weight, or power to volume ratio. A lithium-ion battery is about half the size of a led-acid battery with the equivalent power output.
Lithium-ion batteries are effected less by temperature, when it gets cold the ability of a led-acid battery to effectively recharge is greatly reduced.
No maintenance is required with lithium-ion batteries, led-acid batteries need to be constantly monitored to make sure the liquid contained within them is at the correct level, a well ventilated area is also needed to house led-acid batteries as they can vent hydrogen which is a product of the reaction inside, lithium-ion batteries however do not have this problem.