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How Far Exactly Can An Electric Vehicle (EV) Travel?

Sambit Sengupta
Sambit Sengupta, Associate Director – Field Applications, Avnet India

Since 2017, many countries have announced or begun setting timelines for banning sales of conventional vehicles. In a recent gazette notification, the Ministry of Heavy Industries and Public Enterprises said that the Indian government has increased the outlay for the first phase of Faster Adoption and Manufacturing of Hybrid and Electric vehicles (FAME) scheme to $126.74 Mn (INR 895 Cr). The FAME scheme is part of the government’s ambitious National Electric Mobility Mission Plan to convert at least one-third of the automobiles on Indian roads to EVs by 2030.

This is exciting yet unsettling news for automobile makers. On one hand the direction has been set, removing any lingering hesitation but on the other hand, purely from the perspective of recharge mileage, few commercially available EVs fulfil consumer expectations at this moment. To date, the 500km range achieved by Tesla’s Model S (global scenario) still holds the record in terms of EV development.

According to a study by the Federation of Indian Chambers of Commerce & Industry (FICCI), the conversion to 100% EV will save India more than $300B or INR 20Lakh Cr in the form of oil imports. This industry will require extensive support from the government to survive and grow. Initial policies that subsidize buses and individual cars will now be extended to 2-wheelers and other vehicles like auto rickshaws. What is heartening to see is that even though a concrete EV policy is still awaited and there has been scale down of the EV adoption target from 100% to 30% by 2030, end users in small and medium-sized towns are readily accepting e-rickshaws and small EV vehicles.

Therefore, “how far can an EV travel” is no longer just a question of mileage range technology but also one of great concern to businesses within the field, or rather how much more the industry can achieve. Quite understandably, this has become a major issue of concern.

From the technical perspective, two problems must be resolved so EVs can “travel further”: increasing energy density and conserving energy. “Increasing energy density” pertains to improvements in power battery technology so that vehicles are equipped with higher energy capacity while “conserving energy” refers to better battery control and management so as to improve operational safety efficiency and optimize potential. This is where the Battery Management System (BMS) comes into play.

Let us temporarily put aside unrealized technologies not yet commercially viable and focus on lithium-ion battery technologies that are already in use commercially or nearing market launch. Lithium-ion batteries are typically categorized according to the electrode material used. Types that can be categorized by their use of cathode materials include the lithium manganese battery, lithium manganese iron phosphate battery, lithium iron phosphate battery, and ternary battery. Categorized by the use of anode materials, they can be differentiated into graphite and lithium titanate batteries. See Table 1 for the performance and properties of these batteries.

primary batteries

Among them, lithium manganese batteries melt easily under high temperatures and perform poorly in terms of stability and safety. Lithium manganese iron phosphate batteries are not yet technologically mature and have a short lifespan. Neither of the above are therefore suitable for powering EVs. Lithium iron phosphate batteries exhibit stable voltage and are economical, able to withstand temperatures up to 800℃, and highly safe. For these reasons, they are widely applied in electric passenger cars that require high battery energy levels, long run time, extended lifespan, and high safety performance. Meanwhile, ternary batteries have high energy density, long lifespans, and are able to withstand temperatures of up to 200℃, but cannot be manufactured into high capacity single cells due to safety constraints. They are however becoming increasingly prevalent in the passenger car market where demands on spatial constraints, mileage range and energy density are high. For example, Tesla uses ternary batteries supplied by Panasonic. For this to be adapted to Indian conditions, we must have local innovators producing and supplying in India.

Innovation in anode materials is another key to improving battery performance. Lithium-metal dendrite precipitates on the surface of the carbon electrode during overcharge that can pierce the membrane separator in the middle of the battery, causing internal short-circuit and thermal runaway. This has always been one of the safety concerns of lithium-ion batteries. If lithium titanate is utilized as the anode material, however, lithium-metal dendrite will not precipitate, thereby eliminating the risk of thermal runaway. Such batteries perform well in low temperatures, exhibit high power efficiency, and can be charged up to 10,000 cycles. Lithium titanate batteries nevertheless have several disadvantages such as high-temperature flatulence, lower inherent voltage, and high cost. Therefore, they are currently used mainly in low range scenarios or hybrid vehicles and do not contribute much to a longer travelling distance. It is worth noting, however, that lithium-titanate batteries have the advantage of fast recharging, a feature that may change user conceptions of battery charging from “charge once for a long distance” to “recharge along the way”.

Developing new battery technologies and enhancing battery mileage range are now no longer the objectives of individual enterprises, but have escalated into national strategies. Countries all around the world are now formulating plans to develop power battery technologies. For example, the US Department of Energy has proposed a series of technological improvements to increase battery energy density from 100W.h/kg in 2012 to 250W.h/kg in 2017. In India, while plans are not firmed up, BHEL and Libcoin are reportedly in talks to form a consortium to initially build a 1GWh lithium-ion battery plant in India. The plant’s capacity will be scaled up to 30GWh in due course.

Even though we have yet to identify a clear winner from existing power battery technologies, and a perfect solution for EV application has yet to emerge, the sheer amount of resources that have been poured into relevant developments can perhaps serve as an assurance that future prospects remain bright.

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