Electric Vehicle Battery Market: Exploring the Batteries Involved

Suba Arunkumar, Industry Analyst, Energy & Power Systems Group
Frost & Sullivan

Passenger cars have become ubiquitous. In 2008, we witnessed production of 53 million cars, accounting for 87 percent of the total motor vehicle production. Starting batteries, known as starting, lighting, ignition lead acid batteries, generated the highest revenues in the battery industry when compared with other chemistries. Despite being a well-established market with high growth potential in developing economies such as China, India, the Middle East and Brazil, the search for the right alternative to replace conventional gasoline-powered passenger cars has begun. Vehicle emissions and atmospheric warming are the primary reason to replace conventional combustion powered automobiles. In developed countries, various types of government and non-profit organizations are providing active support and promoting alternative vehicles powered by batteries. In addition to emission controls, a widespread use of these alternative vehicles creates a significant reduction in dependency of the fast depleting natural oil.

Advanced hybrid electric and electric vehicles (EVs) are expected to reduce the dependency of oil and improve air quality by limiting carbon emissions. The importance to these vehicles increases daily, and many government initiatives are being introduced to support and promote these vehicles. The European Union and the US are actively supporting these vehicles through various legislations, tax incentives and federal grant support. Because of these measures, the EV, and subsequently the EV battery market, has become one of the most dynamic industries in which most vehicle manufacturers and battery suppliers are participating.

Performance expectations for these vehicles grows each year, which increases the responsibility of vehicle manufacturers to deliver an EV that performs similarly to the available gasoline-powered vehicles. Since batteries form an integral part of these vehicles, it directly influences battery suppliers to develop the most efficient, reliable, lightweight, small-sized and cost-effective batteries. As the EV battery market emerges, manufacturers are in the R&D phase of developing different chemistries that could cater to all customer expectations and demand.

Batteries: An Overview
EVs are powered by different battery chemistries including lead acid, nickel metal hydride, sodium nickel chloride and lithium-ion. Each of these chemistries possesses distinct features based on its use for powering EVs. The ones developed during the initial stages of alternative vehicles used lead acid batteries, but with increasing use of these vehicles, other chemistries proved much more effective than lead acid. However, lead acid batteries have proved to be the most reliable battery chemistry available at an affordable price to customers. Low energy density is the major reason that dampens widespread use of this chemistry in EVs.

Extensive research is ongoing to improve the energy density of lead acid through modifications for electrode and electrolyte. Such batteries are noted as high-powered or advanced lead acid batteries, which are aimed to power EVs. Among the very few manufacturers is Firefly Energy, Inc., the company that has modified the electrodes of lead acid batteries. These batteries could power EVs at a lower cost than the competitive chemistries. However, when comparing based on the inherent features, lithium-ion is the chemistry most portrayed as a suitable battery for all types of EVs. A precise comparison of the major battery chemistries used in EVs is represented in the figure below.
Note: Cycle life depends on the vehicle type and usage. Values refer to comparative advantage of lithium-ion cells.

Based on these comparisons, it is observed that lithium-ion batteries offer superior performance compared with other battery chemistries. However, the safety aspect of the lithium-ion battery is ensured through rigorous testing methods.

Exploring the Lithium-Ion Family
Lithium-ion refers to a family of batteries that have lithium as anode and different cathode materials. With increasing growth potential in EV applications, different cathode materials are evaluated that could satisfy all the demands and expectations of the user. Lithium cobalt oxide is the commonly used lithium-ion battery for consumer application. This chemistry is thermally unstable, which led to explosions in many consumer devices (specifically laptops). Recognizing this feature, battery manufacturers are developing lithium-ion batteries with alternative cathode materials such as manganese, iron phosphates, nickel cobalt manganese, titanium oxide and the like. Among these, the most widely adapted chemistry includes lithium manganese oxide and lithium iron phosphate that are developed by many battery manufacturers to power EVs. A comparison of these different chemistries within the lithium-ion family gives a fair idea on the type of application for which each battery is best suited.

As expressed in the Figure 2, lithium cobalt oxide is successful lithium-ion chemistry with unit volumes of billions of cells every month for consumer application. However, this chemistry is not suited for automotive application. The key difference between these batteries employed in consumer and automotive applications are listed:
• EV batteries require high energy capacity, mass and volume compared with batteries used in consumer applications.
• EV batteries are a part of battery management systems, in which monitoring and control processes are connected to the battery cells that are interconnected with each other to form a module.
• EV batteries are subjected to vehicle control system, during vehicle usage.
• A safety mechanism to automatically shut down the power supply from the battery is installed in EV batteries.
The responsibility, expectation and the output from an EV battery is much higher than those expected from a battery for consumer application.

Evaluation of Lithium-Ion Batteries
Lithium-ion batteries include different cathode materials, each with different distinct features. Each of these chemistries exhibits different results when subjected to a rigorous test process that could help in identifying the most suitable chemistry for the specific type of EV. The test procedure involved in evaluating these battery chemistries are listed:
• The testing process starts from testing the cells, followed by testing modules and then proceeding to testing packs.
• Subjecting the cells, modules and packs to constant current (the time taken by each chemistry to discharge from one voltage to another keeping the current constant) and constant power ratings (time taken by each chemistry to discharge from one voltage to another at constant power rating)
• Subjecting the cells, modules and packs to pulse tests at various state of charge
• Testing the cells, modules and packs to life cycle test to evaluate the charge discharge cycles it can operate
• Subjecting the cells, modules and packs to fast charging tests to evaluate the time taken by each chemistry to charge to 80 percent of its full capacity

The Figure 3 depicts a snapshot view of the performance of different chemistries from an end-user’s perspective.

Conclusion
Determining the best fit battery chemistry for powering EVs is a complex process in which different parameters need to be considered. After such careful evaluations, most of the battery manufacturers and EV makers concur that lithium-ion chemistry has good potential to cater to demands. However, as the market still emerges, lithium-ion battery chemistry is yet to prove its capabilities. With the development of the right chemistry at an affordable price, EVs have every possibility to change the dimension of automotive industry and make automobiles completely environmental friendly.

Contact Frost & Sullivan at www.frost.com.

Click here for reuse options!
Copyright 2010 WebCom Communications Corp.