There are many varieties of lithium batteries available, serving different applications in numerous ways, with pros and cons of each, writes Zenaji CEO Dawson Johns.
The lifespan and performance of a battery is defined by its cell chemistry, with cell performance characteristics determining the size, weight, voltage, current, power and environmental capabilities of a battery pack. Common lithium chemistries are lithium cobalt oxide (LCO), lithium nickel cobalt aluminium oxide (NCA), lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP) and lithium titanate (LTO).
Some battery chemistries suit various applications better than others. For example, LFP and NMC batteries are preferred to other battery chemistries in cars, principally because they feature excellent energy density. This makes them lighter than other chemistries, meaning the vehicle doesn’t have to carry as much weight for the high power it requires to operate.
Also, cars don’t require batteries to be deep-cycled when used under normal circumstances because users don’t drive their cars enough each day to actually flatten the battery. Each vehicle only uses a small proportion of the energy store in its batteries each day and therefore they last for many years.
However, there are significant downsides to LFP and NMC batteries: they have a limited life.
They are not good for towing as this puts major stress on them, and the engines they power are not usually designed or engineered for this purpose.
They are not particularly safe, either. For example, thermal runaway remains an issue and fires can happen and are difficult to put out when they occur. The cost or replacement of them is high, and because they have a more limited life expectancy than other components of a car, this may be a problem in the future.
Mobile phones, laptop computers and power tools thrive using LFP and NMC chemistries. Being lightweight with excellent energy density usually makes them the first choice for these applications. The world is currently building many large-scale factories – particularly in India and China – to cater for the increased demand expected for these batteries in years to come. Currently, demand is outstripping supply and the costs of the base components, especially lithium, is rising as a result.
NMC battery cells are displacing LFP cells in some applications due to increasing power ratings, high energy density and lower cost per watt-hour. They’re also starting to replace LFP cells in high-power systems such as power tools, batteries for material handling equipment, and powertrains for electric buses.
So what about other chemistries, and where do they fit?
There are many demands on batteries where LFP and NMC chemistries are not suitable. These include applications which require one or more of the following characteristics: higher power ratings, ultralow weight, greater cycle life, lower and/or higher temperature tolerance, greater safety, longer life, and a lower cost of storage/retrieval during the life of the battery.
LTO fits most of these demands. It is safer because it doesn’t suffer from thermal runaway; has a cycle life approximately eight to 10 times greater than NMC or LFP; can handle very high or very low temperatures; and due to its lifespan and cycle life, it provides very low energy storage and retrieval costs.
LTO can output extraordinary power to suit applications needing instant amounts of high current. It is very well suited to stationary applications such as grid storage, home storage, heavy transport and high-power users. However, as LTO is approximately twice as heavy as LFP and NMC cells, it is less suitable in cars and other transportable power applications.
For some applications, LCO, NCA, NMC, LFP and LTO lithium cells may not be the best performing batteries. For ultralight applications, such as model aircraft and drones, other chemistries may be suitable.
For very low usage applications, such as combustion engine car batteries, it may be cheaper and more reliable to continue to use lead acid batteries.
It’s always advisable to do your homework and choose the right chemistry to fit the need. Try to take into account all the attributes of the battery you are assessing and ensure it addresses your needs now and into the future. Remember, the cheapest battery may end up being the most expensive if you don’t choose wisely.