This is the tale from A123 factor where a technician takes a foil packet out of a white plastic container and sets it within the reach of a robot which scoops it up and adds it to a growing stack of metal plates and foil packets. It’s the start of process that makes one of many types of batteries used in hybrid & electric cars.
Following steps demonstrate the complete process involved in battery fabrication:
1. Battery construction begins with the basic building blocks of the pack—the battery cells. Each of these flat silvery packets contains positive and negative electrode foils separated by a polymer sheet soaked with an electrolyte. The tabs emerging from the edge are positive and negative electrical contacts. The composition of the positive electrode is A123’s key technology—it’s a nanostructured material, made of lithium iron phosphate, that’s designed to be safer and more resilient than the electrode materials commonly used in portable electronics.
2. A robot (the gripper arm is shown at the top left of the photo) is used to create precisely aligned stacks of cells and metal heat sinks. Here the robot places a heat sink on top of a nearly complete stack. There are two cells per heat sink; their electrical connections can be seen on the left of the stack.
3. After a stack is complete, workers cap the ends with black plastic and bind the stack with metal straps. The size of a stack—also called a battery module—varies depending on the application. Groups of small modules, such as this one for the Fisker Karma sport sedan, are used when packs must fit into confined spaces. They’re also used for starter batteries. Larger ones, like the stack in the previous picture, can be used for larger electric vehicles, such as delivery vans. Here, a worker adds a bus bar to the module. These pieces of metal connect the electrical contacts of the individual cells.
4. In the next step, dozens of temperature and voltage sensors are added to the pack. This picture shows the wires leading from these sensors down the middle of the pack to a white plastic connector. The connector plugs into an electronics board that monitors the sensors and communicates with the battery pack’s central controller. The charging of each cell can be controlled separately to ensure that the cells are not overcharged, which could damage them. The temperature is controlled by a liquid cooling system.
5. Then a technician installs the completed battery module inside the housing of the
battery pack, next to three other modules. the modules sit on their sides, on top of what looks like a solid slab of aluminum (obscured). the slab is plumbed with tubing for coolant that keeps the cells within an optimal temperature range—a key to making them last the life of a vehicle. to keep the pack cool, the coolant flows past the modules and then through a radiator. in some applications, a heater warms up the coolant on cold days.
battery pack, next to three other modules. the modules sit on their sides, on top of what looks like a solid slab of aluminum (obscured). the slab is plumbed with tubing for coolant that keeps the cells within an optimal temperature range—a key to making them last the life of a vehicle. to keep the pack cool, the coolant flows past the modules and then through a radiator. in some applications, a heater warms up the coolant on cold days.
6. This is an example of one type of completed battery pack. it’s mounted on rails that can be bolted to a vehicle. coolant flows in through ports on the back of the pack. A123 won’t say exactly what vehicle this pack is designed for, citing confidentiality agreement with its customers
Source: Technolog Review April 2011
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