Silicon nanomaterials are promising anode materials for lithium-ion batteries (LIB) due to their high theoretical capacity. However, their practical application is hindered by poor electrical conductivity and severe volume expansion during cycling. Among these materials, silicon nanocrystals (SiNC) offer tunable particle size and surface properties that strongly influence electrochemical performance. This study systematically investigates how anode fabrication strategy and SiNC structural characteristics, including particle size and surface oxidation, affect electrochemical performance under formulation-controlled conditions. Two widely used preparation methods are compared: (i) physical blending of SiNC with a polyacrylic acid binder and Super P conductive carbon, and (ii) hydrogel-assisted synthesis via in situ polymerization of polypyrrole (PPy) in the presence of phytic acid and SiNC, forming a three-dimensional flexible, and conductive network. Comprehensive microstructural characterization combined with galvanostatic cycling, cyclic voltammetry, differential capacity analysis, electrochemical impedance spectroscopy, and post-mortem characterization reveals complementary strengths and limitations of the two approaches. Smaller SiNC improve capacity retention in both systems, with a substantially stronger effect in hydrogel-derived anodes due to enhanced dispersion, component connectivity, and mechanical stabilization, achieving up to 44% capacity retention after 500 cycles. Physically blended Super P/SiNC anodes deliver higher initial discharge capacities (up to 2581 mAh/g), reflecting faster lithiation kinetics, whereas PPy/SiNC anodes exhibit superior long-term cycling stability by mitigating mechanical degradation. Overall, these results demonstrate that electrochemical performance is governed by the interplay between SiNC structural characteristics and electrode architecture, rather than surface oxidation alone. This formulation-controlled comparison provides mechanistically informed guidance for selecting Si-based anode fabrication strategies according to targeted performance requirements. • Anode performance strongly depends on Si particle size and fabrication method. • Smaller Si particles significantly improve capacity retention during cycling. • Physical blending enables higher initial capacity and faster lithiation kinetics. • Hydrogel-derived anodes offer superior long-term cycling stability.
Čandová et al. (Thu,) studied this question.