On September 7, 2021, WHOOP launched its latest wearable fitness device, WHOOP 4.0, which will feature Sila Nanotechnologies’ new battery technology. Their technology replaces graphite anodes with silicon (Si) to increase the energy density of lithium-ion (Li-ion) batteries, which can reduce battery size without sacrificing safety or performance. Sila Nanotechnologies’ anode technology helps enable the WHOOP 4.0’s slim design.  

Compared with the previous model, the WHOOP 4.0 has 17% more energy density with a smaller battery – a 33% reduction in size – and a 5-day battery life. Sila Nanotechnologies developed the new anode technology and created and successfully scaled a production line, a major obstacle to new technologies. Less than 10 years after their first ARPA-E project, the company was able to transition their technology from a concept to the market—as part of a commercially sold product. 

Sila Nanotechnologies initially set out to develop a high-throughput technology for scalable synthesis of high-capacity nanostructured materials for Li-Ion electric vehicle (EV) batteries in 2012, as part of ARPA-E’s BEEST program. The team developed a unique drop-in replacement Si dominant composite anode powder that boosts automotive Li-ion battery energy density by 20%+ and enables fast charging. The Si anode successfully overcame the major challenge of suppressing volume changes during cycling, which can lead to rapid deterioration and degradation of the battery.

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The team is targeting the growing EV market. Sila Nanotechnologies’ anode enables higher density cells, which means longer range for EVs. Sila built a production line and commissioned its first factory to first introduce Si anodes in wearable and portable electronical devices, such as the WHOOP.

Sila Nanotechnologies looks to continue the expansion of its anode powder for other mobile and everyday electronics, as well as for EVs. In 2020, the company was selected to participate in ARPA-E’s Seeding Critical Advances for Leading Energy technologies with Untapped Potential (SCALEUP) program. As a SCALEUP selectee, the company aims to develop a portfolio of technologies focused on more efficient material processing, on-line diagnostics, improved precursor utilization, and improved material handling. This proposed project will significantly reduce Si anode costs, improve efficiency and reduce waste in production, reduce engineering and cost risks, and reduce EV battery costs. The Sila Nanotechnologies team’s targeted efficient, high volume, and manufacturing process could have the ability to produce Si at very large scales and has the potential to accelerate the move to clean transportation and renewable energy.