A Short Introduction to Lithium Ion Batteries
A typical lithium-ion battery cell consists of two sides that can hold charge, the anode and the cathode. Upon charge of the cell, the positively charged lithium ions travel from the cathode (positive electrode) to the anode (negative electrode) through a separator while electrons (the electric current) flow through an electronic circuit to balance the charge. Upon discharge, the lithium ions and electrons travel in the reverse direction.
Traditionally, the key ingredient in a lithium ion battery anode is carbon while different cathode materials include LiCo02, LiMn02, etc. The amount of energy (lithium-ions) that can be stored in the anode and cathode must be equal for a battery to function. The amount of energy per cell (energy density) determines how long the battery lasts — e.g. how far your electric car can drive or your laptop will run.
Amprius goal is to enable batteries with a significant higher energy density, while other battery companies are focused on the power of a battery — e.g. how fast your electric car can accelerate or how powerful your electric drill is.
Amprius has developed an alternative anode made of silicon nanowires instead of carbon. Silicon can hold over 10X more lithium compared to carbon. However, even with today’s best commercially available cathode materials this does not yet result in a battery with 10X greater capacity.
With our first generation product, we can enable a battery with a 4X smaller anode that balances with a 40% larger cathode, which results in a practically usable energy density increase of 40% compared to today’s best lithium-ion batteries. There is clear potential to reach increases of up to 200% or more in the future.
