By Dawson Johns CEO Zenaji
The cell chemistry is what defines the lifespan and performance of a battery. The cell performance characteristics determine the size, weight, voltage, current, power, and environmental capabilities of the final battery pack. The common lithium chemistries in use today are lithium cobalt oxide (LCO), lithium nickel cobalt aluminium oxide (NCA), lithium nickel manganese cobalt oxide (NMC), and lithium iron phosphate (LFP) and Lithium Titanate (LTO).
Different battery chemistries fit different applications better than others. In cars, for instance, LFP and NMC batteries are preferred to other battery chemistries principally because they feature excellent energy density and as such are lighter than other chemistries. This means the car does not have to carry so much weight for the high power it needs. Also they do not require the batteries to be deep cycled when used under normal circumstances i.e. users do not drive their cars each day enough to flatten the battery. This means the car 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 these batteries. They have a limited life. They are not good for towing as this puts major stress on them. Indeed, the engines they power are often not designed or engineered for this purpose. They are not particularly safe either i.e. thermal runaway remains an issue and fires do happen and are difficult to put out when they occur. The cost or replacement is high and as they have a more limited life expectancy and the other components of the car this may be a problem in the future.
Mobile phones, laptop computers, power tools and a many other devises also thrive using LFP and NMC chemistries. Principally their excellent energy density is the key and their light weight usually make 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 the 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 the best fit. These include applications which require one more of the following characteristic’s – higher power ratings, ultra-low weight, greater cycle life, lower and or higher temperature tolerance, greater safety, longer life and a lower cost of storage / retrieval over the life of the battery.
LTO fits most of these demands. They are safer because they do not suffer from thermal runaway, they have a cycle life approx. 8 to 10 times that of NMC or LFP, they can handle very high or very low temperatures and due to their life span and cycle life, they provide a very low cost of energy storage and retrieval. They also can output extraordinary power to suit those needing instant amount of high current. For all these reasons they are well suited to stationary applications such as grid storage, home storage, heavy transport and high power users. However, as they are approximately twice as heavy as LFP or NMC cells so are less suitable in cars and other transportable power applications.
For some applications the all above mentioned lithium cells may still not be the best performing batteries. For ultralight applications such as model aircraft or drones’ other chemistries not mentioned here may be more 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 is always advisable to do your homework and chose the right chemistry to fit the need you are addressing. Try and take into account all the attributes of the battery you are assessing and make sure it addresses all your needs now and into the future. Remember the cheapest battery may end up being the most expensive if you do not choose wisely.
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