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Silicon anodes are emerging as a solution to maximizing energy density in Li-ion EV batteries, CNBC reports citing a report by IDTechEx. They also show improvements in charging speed, potentially outpacing the solid-state batteries.
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In context – The energy density limits of current materials used in EV batteries have been largely reached as demand-driven advancements led to more efficient and durable batteries. Silicon, with its theoretical capacity of nearly 3.6k mAh/g, offers a potential breakthrough, surpassing the 360 mAh/g capacity of graphite — the most used anode material in Li-ion batteries. This could lead to cell-level energy densities exceeding 400 Wh/kg and 1000 Wh/l, potentially doubling the energy density of commercial cells by 2024.
Safer, faster charging, more capacity: Companies developing silicon anode materials report improved power and fast charging capabilities, which are crucial for EVs and other applications like power tools and consumer devices. For example, silicon anode batteries have the potential to double the range of EVs. Recent advancements also suggest that silicon-anode batteries now boast a calendar life of three to four years, an improvement from just one year five years ago. Silicon’s more positive voltage compared to graphite also reduces the risk of lithium plating, enhancing battery safety.
Compared to solid batteries- Silicon anodes currently show more promise than solid-state batteries, which have yet to be commercialized on a wide scale. Solid batteries promise higher energy density than typical lithium ones, faster charging, and improved safety compared to traditional lithium-ion batteries. The stability of using solid materials like ceramics for electrolytes has been hailed as key for addressing the shortcomings of liquid Li-ion batteries. However, challenges such as battery swelling and degradation during charging remain. Analysts suggest that semi-solid-state batteries, which combine solid and liquid electrolytes, might serve as a transitional technology.
Challenges remain: The new tech faces challenges such as cycle life, shelf life, durability, and cost. While silicon anodes offer ten times the energy density of graphite, they suffer from rapid degradation when used extensively, said Benchmark Mineral Intelligence’s senior research analyst Rory McNulty. Silicon oxides are also currently used at low weight percentages (<10%), but numerous companies are racing to develop advanced materials that can enable higher silicon percentages in batteries. Efforts to overcome these hurdles have shown promising results, with cycle lives of up to 1k cycles being reported. However, shelf life and cost remain concerns. In the short to medium term, silicon anode materials are likely to come at a price premium over graphite, limiting their possible deployment to high-end applications where price sensitivity is lower.
Investment in the tech is ramping up: Investments in silicon anode start-ups have reached USD 4 bn since 2010, with IDTechEx predicting the market for silicon anode batteries to reach USD 24 bn in 2034.
Who is in? Several industry players are investing in silicon anode technology. Taiwanese company ProLogium — also a major solid-state battery player — recently showcased the world’s first fully silicon anode battery, claiming it surpasses traditional lithium-ion batteries in performance and charging efficiency. ProLogium’s battery can charge from 5% to 60% in just five minutes, a groundbreaking achievement in the EV market. Companies like the US-based Amprius Technologies, Enevate, Sila Nano, and Group14 have their own efforts in various applications, including drones and e-motorcycles. Automotive giants such as Daimler, Porsche, and GM are also investing in and partnering with silicon anode companies.
What’s next? Advances in silicon anodes are seen as a way for Western companies to catch up with China, which dominates 98% of the graphite-based anode market, Fastmarkets’ battery raw materials analyst Georgi Georgiev said. Yet, commercialization and scaling up are still at question, given the current projected production costs.
