Raising the Range

Technology innovations to increase the energy density of EV batteries

In line with the target of deploying 30 per cent electric vehicles (EVs) by 2030, India is expected to become a major manufacturing hub for batteries. According to IESA’s estimates, between 2018 and 2026, the EV market will grow at a CAGR of 36 per cent, with total sales of 14.2 million units. Further, the EV battery market alone would be worth as much as $16.5 billion, with the demand for batteries expected to be at least 112 GWh.

An EV uses one or more electric motors or traction motors for propulsion. It may be powered by a collector system using electricity from off-vehicle sources, or by a battery, solar panels, or a generator that will convert fuel to electricity. It uses electricity stored in a battery pack to power the motor and turn the wheels. The controller regulates the amount of power received from batteries, preventing the motor from burning out. An EV may be battery operated, hybrid or plug-in hybrid. Since a battery accounts for about one-third of the total purchase price of an EV, driving down battery costs by rapidly scaling production and standardising its components could be a key element driving the long-term success of India’s automotive sector. Domestic battery manufacturing is witnessing a surge in interest from domestic and global players given the government’s thrust on e-mobility.

New battery technologies

The energy density of existing battery technologies is much lower than gasoline. The driving range of an electric car depends on the size of the battery pack, which in turn depends on the energy density of batteries. An increase in the driving range can significantly reduce range anxiety. Lithium-ion (Li-ion) batteries used in EVs have different chemistries and specific characteristics. The most common ones are:

  • NMC-graphite battery cells: These battery cells use nickel-manganese-cobalt chemistry (NMC) as cathode and graphite as anode. These are the most commonly used EV batteries today as they provide specific energy of 200 Wh per kg or more and the cell costs are in the range of $150-$200 per kWh. They are typically charged at 1C or 1.5C and are used with a discharge depth of about 80 per cent. If charged and discharged at 25 °C, these batteries can run for 2,500 life cycles. The cell chemistry, however, has safety issues at high temperatures and is generally not recommended to be used as cell temperature touches 55 °C. If charged or discharged at 45 °C, or at 3 °C, the life of these batteries may reduce to as low as 500 cycles. Thermal design incorporating heat dissipation is therefore an important element of battery packs.
  • NMC-LTO: These cells use lithium-titanium-oxide (LTO) as anode instead of graphite. They are powerful cells, which can be charged and discharged at 10 °C. They have more than 10,000 life cycles and can withstand 60 °C temperatures, without impacting life cycles. However, their specific energy is 80-100 Wh per kg and the current cost exceeds $450 per kWh. Therefore, they are used only in specialised vehicles that use smaller batteries that charge and discharge frequently.
  • LFP-graphite: Batteries with lithium-ferrous-phosphate (LFP)-graphite have a slightly higher number of life cycles than NMC-graphite, can better withstand high temperatures and are, therefore, safer. However, their specific energy is about 140 Wh per kg with a theoretical limit of about 160 Wh per kg. They do not compete with NMC-graphite in terms of weight or costs and are thus, fast being discontinued.

In addition to currently available Li-ion chemistries, future developments in battery chemistry may give rise to a new generation of batteries, including solid state batteries that promise a storage capacity of about 1,000 Wh per kg and 80 per cent charge in about 10 minutes. These batteries, however, are still at laboratory scale and will take time to become commercially available. Ultra-capacitors, an alternative to batteries, are also upcoming potential energy storage systems. New technologies such as Zn-air, Li-S and Li-air have a much higher energy density than existing Li-ion batteries.

Older cathode materials such as LMO and LCO have been replaced with newer materials such as NMC and NCA, which are lighter and safer with a longer life cycle. Oxygen has a theoretical capacity of 3,350 mAh per gram. This is the main reason for the interest in Li-air batteries. Sulphur has a capacity of 1,672 mAh per gram, which is almost eight times higher than the current best cathodes (NMC and NCA) used in conventional Li-ion batteries. Hence, lithium sulphur batteries are very attractive due to their four to six times higher energy density compared to Li-ion batteries. Sulphur, which is the cathode material, is an abundantly available resource (no mining required). The cost of sulphur is almost 100 times lower than that of other cathode materials.

Besides, new anodes for Li-ion batteries are being developed. The silicon anode has more than 10 times higher capacity than the traditional graphite anode. The LTO anode is ideal for fast charge and discharge applications and can be charged and discharged at currents of 10 °C-20 °C.

Non-lithium-based battery technology has also entered the market. It can charge EVs from 0 per cent to 100 per cent in under 15 minutes and increase the number of life cycles. Further, carbon and its derivatives can be used as active material. Since carbon is highly conductive, it can charge these batteries quickly and with the same efficiency as that of any other conventional battery. This will allow customers to charge their EVs conveniently just like refuelling any other petrol vehicle, unlike Li-ion-based batteries for which Indian players still largely depend on cheaper imports. India is home to abundant reserves of carbon, which can serve as the primary raw material.

Issues and concerns

Most consumers today have concerns over range, poor battery life and high initial price. Due to limited domestic expertise, a large number of components for EV, particularly batteries, are imported from China, which are often of low quality. Another challenge is that batteries have a finite number of charging cycles and a limited shelf-life. Therefore, using vehicles as storage can impact battery longevity. Other challenges in the adoption of this technology are high discharge rates and long charging time.

There is also lack of data to quantify system-level savings and cost benefits, which also impacts the adoption of energy storage. Discoms also do not have exposure to advancements in new business models that have been adopted in developed countries. The lack of enforcement of reliability and power quality standards in India for discoms results in manufacturers considering energy storage solutions (ESS) as a high capex alternative. If the reliability and power quality standards are enforced, then ESS can emerge as a cost-effective solution for grid infrastructure. The lack of market mechanisms for driving investments have been major roadblocks in the development of the sector. The externalities of incumbent technologies have also not been captured.

Notwithstanding these challenges, EVs are expected to be the future of the automobile market. In addition to the government’s push, the entry of new players and the increase in the availability of EV models and battery storage are expected to drive growth in this space. A large number of automobile manufacturers, power companies and Li-ion battery manufacturers have announced their plans to invest in this segment.

However, the existing speed bumps in the policy and corporate landscape need to be tackled on an urgent basis. Policymakers need to stop making announcements and focus on a systematic scale-up of deployments. There is an excellent opportunity for collaborations in research and development, manufacturing and exports. This can lead to a robust transmission system, increased flexibility and controllability. Capacity building and skill development also need to be worked on for better results.

Net, net, with FAME II released in 2019, EV sales, charger installations and battery technology innovations are expected to gain momentum.

Nikita Gupta


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