Strategies Toward the Production of Nanoporous <i>SiO<sub>x</sub></i>/C Anodes from the Sustainable Diatom‐<i>SiO</i><sub>2</sub> for Li‐Ion Batteries: A Comparative Study of Different Carbon Amounts Gaarud Anders Thangaian Kesavan Alonso-Sánchez Pedro Blanco Maria Valeria 2025 research-article