Updated: Jul 7
Li-ion batteries (LIB) batteries were initially made for use in laptops, cell phones and other consumer electronics but they have grown to become a major battery technology for power storage systems. In addition, they have become the most common battery type in modern electric cars.
Batteries play the same role in inverter and solar systems, namely, they provide the DC that is to be converted to AC by the inverter for use in appliances. They also store energy produced from solar panels for later use. All batteries have essentially the same components: electrolytes, positive and negative terminals and separators integrated into 'cells'.
These components are often differentiated based on their nature of the material from which they are made. The most important and definitive component of all batteries, the electrolytes, may be in liquid form as in lead acid batteries or in the semi-solid gel form. In the case of LIB, lithium salts dissolved in an organic solvent are used. Also, there may be variances with the type of electrodes or terminals. For LIB, the positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent. (Water is not used as solvent as lithium reacts vigorously with water.)
The most popular negative electrode used in the manufacture of LIB is graphite.
The positive electrode is generally one of three layered materials of lithium salts. Recently, graphene containing electrodes (based on 2D and 3D structures of graphene) have also been used as components of electrodes for lithium batteries.
The electrolyte is typically a mixture of organic carbonates containing mixtures of lithium salts. A modified variant of Li-ion batteries, the lithium polymer battery, or more correctly lithium-ion polymer battery (abbreviated as LiPo, LIP, Li-poly, lithium-poly and others), uses a polymer electrolyte instead of a liquid electrolyte.
Their main attraction is that they do not require constant maintenance. They are a type of the sealed maintenance-free battery types. Read about the SMF battery types here.
Also, they weigh far less than other types of rechargeable batteries of the same size and output capacities. The reason is because the electrodes of a lithium-ion battery are made of lightweight materials. They take up less space and are thus more suitable when there are space considerations.
They do not have to completely discharge before recharging, as with some other battery technologies. They have very much longer life than other battery types.
Comparatively, Li-ion batteries charges extremely faster than other rechargeable batteries. The reason is because while lead acid batteries require a three stage charging profile where each stage progressively lowers the charge current and can be bulk-charged up to 80%, then absorption-charged from 80% to about 95% and then float-charged to 100%. Li-ion batteries however do not have such a similar three-stage charging and can be bulk-charged all the way up to 100%.
Li-ion batteries can withstand very rugged power conditions than other type of batteries. They can supply electricity to very high power appliances.
Under the same conditions, LIB are far more efficient than lead acid batteries. Lead acid batteries only have a charge efficiency of 85%. This means that for every 1A sent to the batteries, only .85A are stored for use. Lithium batteries however have a charge efficiency of 99% so nearly every amp sent to them is stored and usable. Therefore, a lead acid battery bank will require a 15% larger – and more expensive – solar array to charge it as fast as a comparably sized lithium battery bank.
The lifespan of lithium batteries is significantly higher than that of normal lead acid batteries! Some manufacturers warranty their Li-ion batteries to last 10,000 cycles. Most lead acid batteries are only rated for 400 cycles or less. This means li-ion batteries will last ten times longer than their lead acid counterparts! In addition, deeper discharge levels reduce the number of cycles from lead acid batteries. Li-ion batteries are less affected by deep discharge.
The single most important disadvantage of LIB is their cost. They cost up to three times the cost of conventional batteries per Ah.
They are extremely sensitive to high temperatures. Heat causes lithium-ion battery packs to degrade much faster than they normally would.
They have a very low shelf life thus, when in storage, they have to be recharged from time to time. Also, they have to be stored under temperatures lower than 40 degrees. (The shelf life of a battery is the time an inactive battery can be stored before it becomes unusable. It is usually considered as having only 80% of its initial capacity. The conditions under which a battery is stored either by the dealer or the user will determine its shelf life and in turn, eventual lifespan. Read more here.)
Again, if they are completely discharged, they will be permanently damaged. Typically, this is accounted for as many inverters will automatically shutdown when their batteries are being discharged below their depth of discharge because the batteries may be permanently damaged if fully discharged.
They require an on-board protection circuit to maintain the battery voltage. This makes them even more expensive than they already are because of their manufacturing costs. The goal of the protection circuit is to limit the peak voltage of each cell during charge and prevent the cell voltage from dropping too low on discharge. In addition, it helps to monitor the cell temperature to prevent temperature extremes. With these precautions in place, the possibility of metallic lithium plating occurring due to overcharge is virtually eliminated.
There is a small chance that, if a lithium-ion battery pack fails, it will burst into flame.
There are often transportation restrictions on the shipment of larger quantities. (This restriction does not apply to personal carry-on batteries.)
Li-ion batteries come mostly as pre-installed batteries on portable inverters, inverters built for marine applications, yachts, traffic lights and security systems. Luminous Regalia 900 comes with a pres-installed Li-ion battery. Most portable inverters make use of Li-ion batteries. (Read about portable inverters here.) USA battery makers, Trojan makes a range of LIB, Trillium. Indian battery makers and the makers of Microtek Inverters, Okaya also has an wide range of LIB. The Tesla Powerwall are li-ion batteries.
While lead-acid batteries are far cheaper and still very far from being obsolete, mostly due to the cheap cost of production, Li-ion batteries are growing very fast in popularity. Due to LIB's rising popularity and its advantages over lead acid batteries, the general industry perception is that lead acid battery technology is outdated. Li-ion batteries may very well be the battery technology for power storage systems of the near future. However, the world's supply of cobalt and nickel, two metals used in the manufacture of LIB, is also being strained by the rising popularity of the battery technology. Owing to this, cobalt and nickel prices have risen significantly. Regardless, the number of applications for lithium ion is growing rapidly.
FUN FACT: The 2019 Nobel Prize in Chemistry was awarded to three scientists, John Goodenough, M. Stanley Whittingham and Akira Yoshino “for the development of lithium-ion batteries”.
More: Read about another type of battery, OPzS and OPzV battery here.