Lithium-ion batteries are literally everywhere – from laptops and cell phones to hybrids and electric cars. This technology owes its popularity to the light weight, high energy density, and ability to recharge.
Lithium-ion batteries have four main components:
- Anode (positive cobalt-oxide electrode) and cathode (negative graphite electrode) which store the lithium
- Separator which blocks the flow of electrons inside the battery
- Electrolyte carrying positively charged lithium ions from the anode to the cathode and vice versa through the separator
- Two current collectors (positive and negative).
While the battery is discharging, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. The battery is fully charged when no more ions flow. When the battery is getting charged, lithium ions are released by the cathode and received by the anode. If all the ions have moved back, it means that the battery is fully discharged.
All lithium-ion batteries are deep cycle, meaning they have the ability to be fully charged and discharged, and thus can be used for solar energy storage. In 2015, Tesla announced their new lithium-ion solar battery, Powerwall 1, which became an important milestone in the development of cost-effective solar batteries.
Before the Tesla Powerwall, most solar storage systems were composed of lead-acid battery banks. Today the solar market offers a range of lithium-ion solar batteries, which, however, have the only drawback – much higher prices compared to those of lead-acid batteries.