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A Look at Lithium-Ion Batteries

At ISRI’s recent Convention & Exposition in New Orleans, ISRI was honored to have Michael Burz, president of EnZinc, a green battery startup, discuss advanced automotive batteries, from origin to their implications for recycling.

The rapid rise of devices such as smart phones and electric cars would not have been possible without the introduction of the lithium-ion (Li-ion) battery. A wonder of electrochemistry, Li-ion batteries have more than five to eight times the energy of a lead-acid battery. That amount of energy available in a small package has enabled smart phones to act as both a phone and portable computer. It changed the perception of electric cars from glorified golf carts to desirable high performance automobiles.

An electric vehicle uses a battery system made up of several levels of components. The most basic is the electrochemical cell. Dozens to hundreds of cells are grouped into modules. Several modules are grouped into a battery. All of that energy, potentially thousands of cells, must be managed, controlled, and protected by a battery management system, a cooling system, and armor. These are added to the battery and installed as a battery pack.

The battery management system (BMS) is basically a computer that manages the electricity going in and coming out of the battery. It ensures that cells are not overcharged and that right amount of energy is sent to the electric motor and to the auxiliaries like the entertainment system and air conditioning. It also monitors each module to ensure that a cell is responding properly and has not gone rogue, which could portend overheating and an explosion. The BMS can isolate that module and report on it to the car manufacturer.

The Li-ion battery needs a cooling system to keep the cells from going rogue. Just as a laptop gets warm after an hour or so of use, an electric car battery undergoes the same warming except on a much-larger scale. Moving and accelerating a car draws a lot of current from a high-energy battery, which means the battery can get hot. The cooling systems can either use air or, typically, a liquid glycol based system.

The armor is part of the battery pack installation. It is essentially a steel plate that covers the bottom of the car where the battery is typically installed. It protects the battery from objects on the road or during an accident that could penetrate the battery structure and damage the cells. Damaged cells could go rogue.

The technical term for going rogue is “thermal runaway.” When this happens, the cell has shorted and releases a large amount of energy and therefore heat relatively quickly. A rogue cell can cause the electrolyte and cooling fluid to catch fire and set off neighboring cells. The resulting fire is quite hot and can melt aluminum.

Therefore recyclers who come across an electric vehicle should be aware of and consider the following potential concerns. The first is the battery is very heavy. Depending on the kilowatt-hour size of the battery (the more kWh the more range) the weight could be anywhere from 700 to 1,300 pounds. The second is the electric vehicle manufacturers have different approaches as to what to do with the battery. A Li-ion battery needs to be reprocessed (not recycled) by a specialist firm, so check with the manufacturer or local dealer as to what to do with it. Each manufacturer has a manual, typically found on their web site, of instructions to first responders. This would be a good place to start. A qualified electrician needs to help with removing the battery from the vehicle. And finally, an electric vehicle must not be crushed or shredded with the battery pack installed. A battery pack going rogue can severely damage or destroy equipment and harm employees.

So be safe—respect the energy within the battery pack, and check with the manufacturer before disassembly.

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