Lithium Nickel Manganese Cobalt Oxide (NMC) are Lithium Iron Phosphate (LFP) have emerged as prominent lithium battery chemistries for electric vehicles
The battery technology for electric vehicles (EVs) has evolved substantially over the last two-three decades. The evolution of EV batteries over the years has been such that any battery chemistry would have some level of deficiency that incentivised the development and deployment of new battery chemistries in the market aimed at overcoming those deficiencies. Typically, the strength of such EV batteries lies in offering good energy density, faster charging, operating for large number of duty cycles as well as operating for a wider range of temperature.
Lead acid was the first battery technology to hit the EV market many decades back, and subsequently nickel metal hydride (NiMH) batteries marked their entry in the automotive space, but it was more widely deployed in first generation hybrid vehicles. But lead acid and nickel metal hydride batteries over the years lost out on popularity owing to various deficiencies. This heralded the arrival of lithium-ion batteries in the market in the late nineties for various applications, including the automotive space. “All these battery chemistries have some strengths and weaknesses that make them eligible for some specific application or a specific kind of operating environment. A battery that works well at higher latitudes and much cooler regions or countries may not work in a tropical climate like India. Every geography has a set of drivers that will drive adoption of certain battery chemistry. Every nation owing to their specific issues will have their own unique adoption strategy. There are differences in the way vehicles are used in India and other countries, so it is the vehicle application and the operating environment that can dictate which battery chemistry will gain prominence,” says Nakul Kukar, Co-Founder & CEO, Cell Propulsion.
It is important to understand that the market witnessed the advent of different lithium-based battery chemistries such as Lithium Cobalt Oxide (LCO), Lithium Manganese Oxide (LMO), Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium Iron Phosphate (LFP), Lithium Nickel Cobalt Aluminum Oxide (NCA) and Lithium Titanate Oxide (LTO). And among these lithium-based batteries, some battery chemistries such as Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium Iron Phosphate (LFP) became mainstream and this can be attributed to their substantial production scale-up over other chemistries over the past decade. In fact, battery chemistries such as Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium Cobalt Oxide have been in the market since early 2000 – largely deployed for non-automotive applications such as smart-phones, laptops, etc. As far as EVs are concerned, Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium Iron Phosphate (LFP) have been deployed in EVs globally over the decade or so, but such battery chemistries have been adopted in India over the last five-six years only. “These lithium-based battery families gained market acceptance because their prices also dropped drastically that triggered customer demand. And because such battery chemistries have been used extensively they score high on the reliability front. NMC and LFP will remain fundamental battery families for EVs as their cells have witnessed significant cost reduction,” explained Nakul.
It may be noted that long-range EVs will be cut out for vehicle users of countries that are large in size and have good road infrastructure. In fact, it has been observed that vehicle users have the propensity to drive more in countries like USA and Canada, and quite obviously long-range EVs will be cut out for these pockets and this is where Lithium Nickel Manganese Cobalt Oxide (NMC) can be an ideal solution. “For long range EVs you need more energy in each cell to effectively manage the size of the battery pack while delivering long vehicle range. NMC makes more sense for longer ranges because in the same dimensions and same weight constraints you can pack in more energy. The NMC battery chemistry will work well in countries that have colder climates and good road infrastructure such as USA, Europe and Canada. For SUV applications where the requirement is for higher power output, some variants of NMC can be leveraged with a high discharge rate,” Nakul pointed out.
Lithium Nickel Manganese Cobalt Oxide (NMC) is said to work well for SUVs, sedans globally and not for the Indian market. Nakul explains why “Poor road infrastructure, congestion, and low range requirement makes NMC not so favourable for EV applications. Typically a 200-km range will suffice for a car driver in India but in USA a car user wants a range of 350-km plus. NMC requires complex cooling systems in hot climate and the range benefit is not worth the effort,” he explained.
However, Lithium Nickel Manganese Cobalt Oxide (NMC) are a preferred battery chemistry option for Indian two-wheelers – a segment that has to grapple with volume and space constraints “There are space constraints to install the battery pack and owing to these unique constraints Indian two-wheelers are opting for NMC battery chemistry as they pack in more energy and use lesser number of cells resulting in small compact batteries that can fit easily in two-wheelers,” noted Nakul.
Lithium Iron Phosphate (LFP) is considered a good solution for Indian three-wheelers – a segment wherein cost is the most important consideration than volume or even performance. “In the Indian context, Lithium Iron Phosphate (LFP) can work well for three-wheelers as it is cost-effective and more reasonably priced than other chemistries. Of course, it is difficult with LFP to offer range beyond 150-km for three-wheelers, while NMC can be an option for long range capability, but then increasing the cost won’t make any sense for three-wheelers," stated the Cell Propulsion CEO.
Lithium Iron Phosphate (LFP) is believed to be a good battery option for long-haul buses and trucks. Buses have adequate volume and mass margin for heavier battery packs, built with lower energy density cells that can offer required range. “LFP becomes a preferred option due to its inherent safety and lower cost even if its energy density is lower as there is enough volume in HCVs and they can easily carry extra mass – even if you add one ton extra weight, still the bus body and structure will be able to handle it”, said Nakul.
For electric buses, there is another important consideration of cell reliability and safety. “In buses you are packing in far more number of cells than any other vehicle and hence your risk is going up. So even if there is a reliable thermal cooling system to protect the cells, the probability of something going wrong is many times more. In such a situation inherent safety of LFP becomes attractive compared to using large number of NMC cells for bus battery packs,” added Nakul.
There is a substantial difference between Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium Iron Phosphate (LFP). Lithium Nickel Manganese Cobalt Oxide (NMC) works well in cold climate and can be riskier in hot conditions and will need a complex and extensive cooling system. “It is easier to deploy Lithium Iron Phosphate (LFP) in warmer climate. However, Lithium Nickel Manganese Cobalt Oxide (NMC) can be effective for two-wheelers even in hot conditions as only a small number of cells have to be packed and hence easier to handle. NMC will bring in much more complexity in hot weather conditions for high performance cars and buses”, elucidated Nakul.
Lithium Titanate Oxide (LTO) is another EV battery chemistry that is witnessing a steady acceptance in the market. LTO offers key benefits such as thermal stability and safety but it offers lower energy density than NMC and LFP. However, its biggest differentiator is its very high inherent safety and high discharge rates. “The high discharge rate of LTO makes it ideal for high power applications such as forklifts, tractors, mining vehicles, etc. Any fully-loaded mining vehicle has large current requirement (1,000s of Amps) to move within mine area. However range is not an issue since it operates within a small area. LTO may not give you the range, but delivers very high power output – it can also work very well for defense vehicles,” he remarked.
Lithium Nickel Cobalt Aluminum Oxide (NCA) is another battery chemistry that is regarded as a less safer version of NMC. “NCA shares similarities with NMC by offering high specific energy, good specific power and a long life span. But it is comparatively less safe and costlier. NCA is a further development of lithium nickel oxide; adding aluminum gives the chemistry greater thermal stability,” he added.
Clearly, lithium-based batteries for EVs will witness considerable new developments in the future, and who knows what new battery chemistries crop up in the market with even higher performance parameters.