Engineering amorphous silicon anodes via molten salt-assisted sodium reduction for lithium-ion batteries
Journal
Journal of Power Sources
Journal Volume
679
Start Page
240220
ISSN
03787753
Date Issued
2026-07-01
Author(s)
Abstract
Amorphous silicon (a-Si) presents a promising alternative to crystalline silicon (c-Si) as an anode material for lithium-ion batteries due to its isotropic structure, which accommodates volume changes during cycling. Scalable and cost-effective synthesis methods for a-Si remain limited. This study introduces a molten salt-assisted sodium reduction method to efficiently produce a-Si from SiO2 nanospheres and nanosheets. In low-temperature sodium reduction, by-product Na2O reacts with SiO2 to form sodium silicate, reducing silicon yield. Incorporating a MgCl2-NaCl-KCl eutectic salt mixture effectively removes Na2O, significantly improving conversion efficiency. XRD analysis shows that optimized conditions yield highly amorphous products: Opt-MS-SiNP and Opt-MS-SiNS. Nanosheets exhibit nearly double the yield of nanospheres due to enhanced sodium diffusion facilitated by their lamellar porosity. Electrochemical testing demonstrates the superior performance of these materials: while commercial c-Si delivers a high initial capacity (3819 mAh g−1) but degrades rapidly (101.89 mAh g−1 after 300 cycles), Opt-MS-SiNS retains 55% of its initial capacity (3381 mAh g−1, ICE 63.6%). Opt-MS-SiNP also shows strong performance (3236 mAh g−1, ICE 65.3%, 56% retention). Heat treatment of Opt-MS-SiNP at 700 °C further improves its initial coulombic efficiency (ICE) to 70.7%, highlighting the potential of this method for producing high-performance a-Si anodes.
Subjects
Amorphous silicon
And molten salt
Anode material
Lithium-ion battery
Metallothermic reduction
Publisher
Elsevier B.V.
Type
journal article