A123 Systems Case Study Analysis

Topics: Rechargeable battery, Lithium-ion battery, Lithium iron phosphate battery Pages: 7 (1878 words) Published: July 8, 2008
A123 Systems

History of Lithium-Ion Batteries

Rechargeable battery evolution accelerated as the world transitioned to instruments enabled by silicon microchip technology from those of bulky electrical components. Mobile devices were designed to be powered by lightweight energy storage systems. The development of batteries for this rapidly evolving market was challenging: •The nickel cadmium battery had been the only option for modern electronics for many years. It was a great improvement over carbon batteries. •Later, nickel-hydride batteries became the technology of choice. •Lithium-ion batteries became available in the 1990s, offering higher energy densities. This technology won out nickel-hydride.

The lithium-ion rechargeable battery offered advantages that were previously unavailable: •Lithium is the lightest of all metals
It had the largest electrochemical potential
It provided the greatest energy content per unit volume
It had no memory effect
Its energy leakage rate was less than half that of NiCd and NiMH •The first of its type was developed by Sony in 1990 with enough cycles to be usable for rechargeable batteries oMass production took place in 1991

oPanasonic and Sanyo quickly developed similar batteries that were on the market by 1994

Big advances in a mature industry like batteries were hard to find. Advances in the field focused only on finding slightly better materials or thinning the layers to improve performance.

Pre-A123 Systems: History of Lithium-Ion battery Innovation

Pre-A123 research group

Professor Yet-Ming Chiang directed a mid-sized research group at MIT that focused on design, synthesis and characterization of advanced inorganic materials; particularly toward electromechanically and electrochemically active materials. These materials can be defined as being capable of converting electrical energy into mechanical work, and of converting chemical energy into electrical work.

Chiang’s group began researching better lithium cathode materials in the mid-1990s. By early 2000, the group began wondering if there might be a new way to push the thickness limitations of battery cells. The wondered if battery layers could form themselves based on the Hamaker Constant for Different Materials. Materials in this case are very small particles. The Hamaker Constant is the measure of force between materials.

Hamaker Constant applied to designing an innovative battery system

Chiang describes how this related to the challenge of revolutionizing battery technology: •“…the Hamaker Constant can have a negative value and cause two materials (particles) to repel each other if immersed in the right medium… we discovered and designed materials systems that organized themselves into an electrolyte separator between the anode and cathode.” (p.453 text, p.5 case study)

Chiang’s basic concept was a key part of a self-organizing colloid concept. His main idea was that he could tailor the forces between materials constituting the battery, deriving a self-assembly process to make a practical battery on a dimensional scale never before possible. The thickness of the separator layer could be as small as a few molecules, with the resulting batteries able to be fabricated in any shape or size. Designing a system of battery materials with a negative Hamaker Constant between anode and cathode was very difficult. Chiang’s team needed to discover a low-index material and a high-index material with key characteristics: •The right optical characteristics

Both anode and cathode materials must conduct electrons
Both must be lithium hosts

Self-Assembling Materials System Development

Chiang’s team mixed methylene iodide, lithium percholate, polystyrene, graphite particles and lithium-iron phosphate particles as a dispersion and poured it into a mold. Copper was chosen as the anode current collector. Aluminum coated with a conducting polymer that has a...
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