California-based Amprius has reportedly produced the first lithium batteries that it claims to have the highest energy density of any battery available. By weight, these batteries have 73 per cent more energy than Tesla's Model 3 batteries, but 37 per cent less in size.
According to Enpower, Tesla's current Model 3 battery is the most advanced, with an energy density of about 260 Wh/kg (730 Wh/l). The latest Amprius battery is a significant improvement in specific energy (energy per unit electrode) and energy density, with a capacity of 450Wh/kg (1150 Wh/l).
Amprius says the impressive performance of the battery is due to its silicon nanowire anode technology. Currently, when you charge a lithium-ion battery, you can effectively pull an electron from the cathode of each lithium atom and move them to the anode through an external circuit, because electrons cannot pass through the electrolyte or diaphragm between the anode and the cathode. Their negative charge pulls positively charged lithium ions through the electrolyte and diaphragm, where they find an electron and embed it into the typical graphite lattice of the anode.
Now, Amprius has replaced the graphite lattice with silicon nanowires. Silicon can store 10 times more lithium than graphite, but it expands and breaks easily, greatly reducing battery life. When you form porous nanowires and arrange them into a "forest" of longer and shorter wires, the company says, silicon is resistant to expansion and cracking, extending battery life and making silicon anodes a competitive technology.
The company said that silicon nanowires happen to be rooted in the anode substrate, so the electrical conductivity (and power) is very high. It said the battery's cycle life was "excellent" and "increasing", although it did not give any figures, adding that the anode was the only part of the battery that was different from other existing batteries, and that the rest could be produced using existing manufacturing methods and components.
It is clear that the world is ready to accept the next generation of batteries, hoping that they will store more energy in smaller size and weight-everything from smartphones to electric cars will benefit from reduced weight or space. emerging technologies such as electric vertical take-off and landing aircraft urgently need batteries to improve flying distances and capabilities.
Of course, energy density and specific energy are only two indicators that batteries need to compete. Thermal performance, safety, charge and discharge rate and cycle life will all play an important role, and price will also play an important role. In fact, Amprius's first customers are in advanced aerospace and satellite manufacturing, which means the battery is still not competitive in price.
