Interesting Article by L. Roué (INRS) and HPQ SiliconGreat post from the PYR Investor Facebook Group: "
Transforming silicon slag into high-capacity anode material for lithium-ion batteries”
Here is an interesting article about the study made by Lionel Rou from the INRS, and HPQ (and PyroGenesis), to convert silicon slag (a by-product of the Purevap QRR) into a high value product for silicon anode. There is still research to do, but it looks very promising.
https://onlinelibrary.wiley.com/doi/full/10.1002/bte2.20220016 Here are some key points: - Currently, most commercialized lithium-ion batteries (LiBs) adopt graphite as their anode material. Silicon could be a good alternative to graphite for the future generation of high-energy density LiBs because of its high specific capacity that is 10 times greater than graphite.
- The low compactness and high surface reactivity of nanostructured Si-based materials are also major obstacles to their commercialization. Moreover, their synthesis is often costly and involves complex multistage procedures, which are difficult to transfer to an industrial scale.
- The mass production cost of Si-based anode is presently about US$15,000–18,000/ton, much higher than the graphite anode price of US$5,000–11,000/ton, despite their limited Si content.
- In this context, high-energy ball milling (HEBM) appears as a cost-effective and scalable method for the production of micrometer-sized agglomerates composed of nanocrystalline or amorphous silicon, displaying the benefits of nanosized powders in terms of electrochemical performance without the inconvenience in terms of compactness, cost, handling, and so forth.
- The cost of the HEBM process (excluding the raw Si cost) was estimated at about US$2500/ton.
- Silicon slag was produced by PyroGenesis Canada, technology provider of HPQ Silicon Resources, as a by-product of the carbothermic reduction process of quartz in high-purity silicon using a vacuum electric arc furnace.
- Due to the intensive energy requirement in the silicon production process, silicon slag represents considerable energy and material loss. In the present study, it is demonstrated that after an appropriate HEBM treatment, this waste can be valorized as high-capacity LiB anode material, exhibiting a specific capacity 3–4 times greater than that of a conventional graphite-based anode.
- The electrode is able to maintain a capacity >1000 mAh g−1 (>3 mAh cm−2) over 100 cycles.
- The irreversible swelling of the electrode is significantly lower with the present Si slag electrode than with a conventional (SiC-free) Si-based electrode, which tends to confirm its better mechanical/chemical stability. Indeed, under similar cycling conditions and using a similar electrode formulation (except the use of a HEBM Si powder instead of HEBM Si slag), an irreversible thickness expansion of 360% was observed after 400 cycles for a Si electrode28 versus only 90% for the present Si slag electrode.
- Additional work is needed to improve the SEI stability to achieve a viable high-capacity anode material. A strategy to stabilize the SEI is by protecting the Si from direct contact with the electrolyte thanks to a carbon coating for instance or by using a smart binder likely to act as an artificial SEI."
Long and Strong in HPQ Silicon and PyroGenesis!