Tesla’s 4680: A Cobalt-Free Silicon Battery Solution
Tesla’s new 4680 battery solution offers a tabless electrode to improve thermal management and deliver 6x the amount of power while decreasing the internal resistance of the battery cell.
Tesla claims the U.S. is responsible for producing 32 GW of electricity through wind and solar solutions yet CO2 levels are through the roof at approximately 425 PPM, a record high. The message from CEO Elon Musk at this year’s Battery Day was partially a call for a transition to a more sustainable form of energy. Tesla plans to be at the forefront of producing affordable electric vehicles (EVs) and energy storage.
The EV battery cell measures at 46mm x 80mm, making it the largest battery size created by Tesla. Image used courtesy of Tesla.
In regard to EV batteries, Tesla plans to cut the manufacturing costs of battery production by introducing the 4680 — a tabless electrode, cobalt-free lithium battery that increases EV supercharging capabilities.
The Structure of Tesla’s 4680 Battery Cell
Standard batteries for electric vehicles are large, pouch styled cells that not only take up plenty of storage space but also weight down vehicles. In order to have a longer range of travel, the battery storages are stacked up which adds weight, cost, and complex design that engineers have to build sensors and other components around. In May of this year, Tesla was approved with its patented design for a cylindrical, tabless electrode, cobalt-free battery cell.
There are several advantages to Tesla’s new battery design. One of them being the change to a cylindrical structure, this creates a shorter path for lithium ions to travel from cathode to anode. 1st-gen Tesla battery designs were pouch style architecture, create a large area for ions to travel through and when they escape to the cathode and anode terminals, causing energy to bottleneck at each end which increases thermal heat and internal resistance.
The elegant design allows for a simple flow of electrons to actively pass without causing an increase in heat. Image used courtesy of Tesla.
The anode of the 4680 battery utilizes raw metallurgical silicon which unlike industry used silicon the structure of the material does not crack when energy is passing through. With the anode being raw silicon, Tesla is able to stabilize the surface of the material and is able to form a robust network of design through elastic ion-coating polymer coating.
A battery’s cathode terminal is required to be a stable structure to handle lithium ions from passing through, which is why most EV batteries use cobalt and nickel. Cobalt is so prominent since it is able to hold its structure during high transmissions of lithium ions. Tesla plans to have a cobalt-free battery, the 4680 uses a nickel-manganese structure which increases the range the EV can travel by 16%.
There is a 5x increase in energy density and a 6x increase in power all due to the new overlaid shape of the 4680 battery. Image used courtesy of Tesla.
The patented tabless electrode is another advantage of the 4680 battery yields. Thermal heat dissipation and internal resistance are what flawed Tesla’s previous battery model, 2170. An issue that was resolved with the next-gen battery was the abundance of electrode tabs throughout the material.
The 2170’s structure is a flat sheet of copper measured at 21mm x 70mm, a large footprint for electrons to flow through but have to stop-and-go with tabs that basically build up heat and increase resistance. This snowballs into higher power loss and the need for more battery cells to be placed in one vehicle. The 4680’s cylindrical structure does not contain tabs which avoid increases in heat dissipation and internal resistance.
Going Cobalt Free
“Simple is hard,” Musk addressed shareholders on Battery Day on creating Tesla’s 4680 battery cell. Essentially a rolled-up copper material allows for a shorter distance for electrons to travel to reduce resistance, heat, components, and manufacturing costs. Tesla announced that they are already integrating the new batteries into EVs. Tesla is moving away from cobalt materials and plans to mine for Lithium in Nevada, where there is a vast amount of lithium that can be found in clay.
