Date: Apr 08, 2019

It was 2007. Apple CEO Steve Jobs announced the iPhone, J. K. Rowling finished her seventh and final Harry Potter novel, and the worst financial crisis since the 1930s was about to hit.

It was also the year that Gene Berdichevsky, an engineer and employee number 7 at Tesla, the electric car pioneer, began questioning why gains in recent years in the energy density of lithium-ion batteries had fallen from 7–8% to 3–4%. With returns from improvements in battery cathode performance beginning to taper, Berdichevsky began to consider the next bottleneck—the poor energy density of the traditional graphite anode.

Tens of start-ups and established materials firms eventually began asking the same question. Many came to the same conclusion as Berdichevsky: that silicon or lithium would be ideal as an anode material. In theory, they are able to hold roughly 10 times the number of electrons as graphite, leading to lithium-ion batteries with 20–40% higher energy density.

The catch is that the anode also absorbs a large number of lithium ions during charging. Graphite handles them well, but a silicon anode swells more than 300%, causing its surface to crack and energy storage performance to drop rapidly. Lithium-metal anodes don’t present an expansion problem, but they are expensive and present other technical problems.

After more than 10 years of R&D, several material developers think they have solved the expansion issues associated with using silicon in anodes, and they are starting to bring their materials to the market. Substantial business challenges lie ahead, not least a potential intellectual property showdown because so many companies are developing technologies in such a narrow field. But it’s clear that the anode’s time has come.

Anode material developers are well aware that the market potential is big and getting bigger as lithium-ion battery use grows in portable devices, electric cars, and grid energy storage. The anode is worth 10–15% of the total cost of a lithium-ion battery, according to Chloe Holzinger, an energy storage analyst with Lux Research. The global anode material market could be worth $10 billion by 2025, she says.

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