In the world of EVs, batteries put themselves into the most integrated focus for the whole industry. While Lithium-ion batteries are rapidly innovating, inversely, the cost seems to still be farcical. In this whole new transitioning custom, fewer have lent their ears to the importance of Lithium-ion Cells. Niloy in its episode of finding the nimble personalities of the EV industry bumps with Rahul Bollini. Rahul is an R&D Expert who has been giving technical advisory for companies planning to set up Lithium-ion cell manufacturing. In this exclusive chat, he exchanges vital insights on Lithium-ion cell manufacturing processes, underlines his extensive knowledge of raw material characterization, technical challenges behind fast charging, the role of cell manufacturers and also emphasizes the amusing cost factor. Don’t miss out on more technical insights in the interesting excerpts below.
Kindly tell our readers about yourself – Journey, domain expertise etc.
My name is Rahul Bollini and I’m an R&D expert with an experience in engineering, fabrication, formation, ageing and grading of Lithium-ion cells. I bring along technical advisory expertise for companies which are planning to set up Lithium-ion cell manufacturing. I’m very well versed in the trends of the Lithium-ion cell industry due to my international network. I also work with companies that are planning to produce raw materials for Lithium-ion cell manufacturing because of my extensive knowledge of raw material characterization before Lithium-ion cell manufacturing. I have been interested in the energy storage space since my Bachelor of Science in Energy Business and Finance at the Pennsylvania State University, University Park, USA.
Can you highlight the key innovations in Lithium-ion Cells?
This space is innovating very fast because of lot of hard work being put by the industry. Better raw materials and better engineering can help batteries to achieve any of the following benefit(s):
- Last longer
- Less bulky
- Charge faster
- Provide higher discharge power
- Usage of abundantly available minerals
The impact on the EV battery cells segment due to the pandemic?
The pandemic has disturbed the price fall trend of Lithium-ion batteries, which was falling at a good rate every year. The prices kept falling till the last quarter of 2021 and then they started increasing for the first half of 2022. This is due to the price rise of raw materials since the beginning of the last quarter of 2021. It usually takes some time for the raw material price to rise to reflect at a cell level.
Anecdotal technical challenges behind true fast charging and the role of cell manufacturers?
Three major factors decide the life of the battery; depth of discharge, operating temperature and speed of charge & discharge during operations.
Fast charging falls under these three major factors that decide the battery life. Faster charging means the life of the battery is going to be lower. Fast charging further induces heat in the battery and leads to additional loss of cycle life of the battery. It is very important to have a thermal management system in place during fast charging of the battery. This thermal management system must be able to actively dissipate the heat away from the battery.
Today the fastest growing market is electric 2-wheelers. Most electric 2-wheeler batteries do not have an effective thermal management system in place because it can add additional costs making their vehicles expensive. Premium-priced scooters use thermal management. Fast charging the batteries in the absence of effective thermal management, especially in hot areas (most places in India) can drastically reduce the battery life. This reduction in life can challenge the warranty terms generally given by electric vehicle companies.
As Lithium-ion batteries are getting lighter and less bulky, their electrochemical stability also tends to shift to the lower side. For example, NMC 811 is lighter and less bulky than NMC 532 but it is less stable. This stability loss comes with a price, which is the reduction of the window of operating temperature, lower cycle life and reduction of the speed of charging.
Choosing the right Lithium-ion cells for EV batteries?
There is no one-size-fits-all when it comes to selecting the right type of Lithium-ion cells for EV applications. It is simply because there are many parameters such as the following that are looked upon while selecting the Lithium-ion cell:
- Chemistry such as LFP, NMC, etc. (Specifies Nominal Voltage).
- Working Voltage
- The capacity of the Cell (Ah)
- Volumetric Energy Density
- Gravimetric Energy Density
- Internal Resistance
- Operating Temperature During Charge and Discharge
- Continuous C Rate of Charge and Discharge
- Maximum Continuous C Rate of Discharge and its Time
- Maximum Depth of Discharge Suggested by Manufacturer
The chances of all the above parameters being of the best value are highly unlikely and hence one has to rank their preferences and decide on the Lithium-ion cell accordingly. For example:
A low-speed electric 2-wheeler manufacturer looking to achieve a short range and price their vehicle in the low-cost market is likely to go for LFP cylindrical (preferably 6Ah) for the reasons that it is relatively cheaper, lasts longer and is safer. On the other hand, a high-speed electric 2-wheeler manufacturer looking to achieve a relatively higher range is likely to choose NMC cylindrical (2.6Ah in 18650, 4Ah in 21700 or 5Ah in 26650). Also, a premium high-speed electric 2-wheeler manufacturer looking for a very high range is likely to choose NCA or NMC 811 chemistry cells, which will allow them to achieve the maximum vehicle range but these chemistries have lower stability and require a battery thermal management system. Similarly, there are various possibilities of types of Lithium-ion cells that can be used in different segments of electric vehicles.
The limited life cycle and available capacity may shift the focus from lead-acid batteries to lithium-ion batteries, and promote the electric EV battery cells markets, how do you look into this transition?
The shift from Lead acid batteries to Lithium-ion batteries is already happening. The electric two-wheeler market has seen a very good transition and 100% of the high-speed electric two-wheeler market is using Lithium-ion batteries. Some branded companies selling low-speed electric two-wheeler follow standard battery specifications while most other companies give an option to the end consumer to pick an option at the dealer stores to choose from Lead Acid and Lithium-ion batteries (NMC and LFP). High-speed electric two-wheeler enjoys FAME 2 subsidy (Rs.15000/kWh or 40% cost of the entire vehicle capped at Rs.60000/vehicle) and this subsidy covers the pricing gap between Lead acid batteries and Lithium-ion batteries. Low-speed electric two-wheelers do not enjoy the FAME 2 subsidy and hence give the battery options to their end consumers. The story of the L3 category electric three-wheeler is very different. It is mostly using Lead acid batteries because of its ultra low cost (after factoring in the rebate for exchanging old Lead acid batteries). Although Lead acid batteries have a very limited life in electric three-wheeler (due to deep discharge and everyday cycling), most people are willing to make frequent Lead acid battery changes and pay small sums of money every time instead of making a bigger investment for Lithium-ion batteries. But this changes slowly after the awareness of the benefits of Lithium-ion batteries is spreading. Benefits include long life, lightweight, takes less space and fast charging. L5 category electric three-wheeler completely uses Lithium-ion batteries and the same is the scenario for electric cars and electric buses.
Silicon and silicon oxides boast a capacity 10x greater than graphite. Furthermore, silicon could play an important role in minimizing any loss in energy density that comes from using LFP over NMC or NCA. Your expert comment on it.
This is a very interesting question. Silicon has a specific capacity of over 3000mAh/g and incorporating it with Graphite increases the specific capacity from 350mAh/g to higher value depending on the percentage of Silicon added. SiGr (Silicon-graphite) is commercialized to be used with NMC 811 and NCA cathodes. This anode popularly used in cells having more than 3Ah capacity in 18650 and more than 4.5Ah in 21700. Using SiGr with LFP is a very good idea and in fact trials are being held in this area. Making any changes in LFP technology and commercialising it for mass manufacturing takes longer than doing it for NMC and NCA because LFP testing and validation take longer. LFP cell testing until end-of-life takes a longer time because of its high cycle life compared to NMC and NCA. I know some companies who are on the verge of mass manufacturing the same and we can expect these cells in 2023. They have a gravimetric energy density of more than 200Wh/Kg in their first stage. More can be achieved when a higher silicon content anode is used. But it is not easy to incorporate more and more silicon since it expands to 3x of its original capacity during intercalation (charging). But the improvement in the volumetric energy density of the LFP with SiGr will be only marginal and it can not reach close to the volumetric energy density of the most basic NMC 532 with graphite cells, which is close to 600Wh/L. This basic NMC 532 with graphite cell already has a gravimetric energy density of close to 200Wh/Kg.
OEMs’ key purchasing criteria for their tier-one suppliers are the lowest cost, track record—for instance, on quality, yield, and reliability—and sustainability. In this environment what key facets should cell manufacturers focus on to be cost competitive from day one?
2W and 3W OEMs either make battery packs in-house or source it from battery pack assembly companies because the market demand is growing very fast. OEMs that source batteries from battery pack assembly companies do put in a lot of efforts to test and validate the batteries. When it comes to bigger vehicle segments, companies make their own battery packs until a certain volume and they might consider outsourcing their pack-making, specially when the demand is growing. Regardless of if it’s a vehicle manufacturer or a battery pack assembly company, they want to be able to get Lithium-ion cells of the best quality at the best possible prices. These companies (OEMs and battery pack assembly companies) expect that any company setting up Lithium-ion cell manufacturing in India has to match or provide better prices than the existing prices they pay for imports (after adding costs of international shipment and customs duty). This price is possible for Indian Lithium-ion cell manufacturing companies to achieve if they develop raw material vendors locally. In fact, there is a great interest in the raw material fraternity to support upcoming Lithium-ion cell manufacturing in India. But it is like a chicken and egg situation where Lithium-ion cell manufacturers will come forward if raw materials manufacturers set up a plant and provide affordable raw materials and raw material manufacturers will come forward if cell manufacturing takes off and they see big volumes in the consumption of the raw materials. With the push of the PLI scheme from the Government of India and manufacturing policies offered by many state governments, we can see some financial benefits in the costs of Lithium-ion cell manufacturing and we can see these plants taking off soon.
Sourcing Lithium-ion cells that are locally manufactured would mean having direct access to the factory and more transparency can be expected. Some traders abroad that don’t manufacture cells falsely brand themselves as a manufacturer and it is difficult to verify the authenticity, specially when the cover on the cell can be changed and anything can be printed.
What are your future plans and agenda to make your projects more advanced and successful?
My focus is to provide technical assistance towards the setup of Lithium-ion cell manufacturing that is soon planned in India and contribute towards the development of manufacturing of raw materials that cater to Lithium-ion cell manufacturing. My goal is to make India a self-sufficient country when it comes to Lithium-ion cell manufacturing. Although some raw materials are unavailable to source locally, I want to maximize my efforts to achieve as much localization as possible.
“Rahul Bollini is a Lithium-ion cell R&D expert with an industrial experience of over 7 years. He is heading Emerging Technologies Division for JLNPhenix Energy and handles new technologies such as Solid State Batteries, BESS, etc. He can be reached at +91-7204957389 and firstname.lastname@example.org”