The global population growth and rising energy demand have spurred the rapid electrification of the transportation sector, with rechargeable lithium-ion batteries (LIBs) replacing conventional fuel-based technologies. To enhance energy density, silicon (Si) anodes are promising due to their high theoretical capacity (~3600 mAh g^-1). However, their significant volume change (~400%) leads to rapid degradation, hindering commercial adoption.
Silica (SiO₂) has emerged as a promising alternative, boasting a theoretical capacity (1965 mAh g^-1) five times higher than conventional graphite, along with a comparatively smaller volume change during battery cycling relative to elemental Si. Despite the volume change for silica being less severe, it still remains significant. To address this challenge, cellulose nanocrystals (CNCs) are employed as a sacrificial template for fabricating highly porous and tubular silica materials via a sol-gel technique. A unique property of CNCs is their chiral nematic phase formation in aqueous suspensions. By leveraging this chirality, it is possible to create three-dimensional (3D) structures through the direct growth of silica on CNC templates.
Our team has devised a patent-pending methodology utilizing bio-renewable templates to synthesize a three-dimensional silica architecture called silica nano-quills (silicaNQs). This economical and eco-friendly process generates silicaNQs characterized by a porous morphology and hollow internal structure, with the option to either remove the CNC template or subject it to pyrolysis for carbonization, thereby producing a carbon-coated silicaNQ. The electrochemical performance of silicaNQs demonstrates an initial capacity of 464 mAh g^-1 and a 32% capacity increase following 200 cycles of testing at a current rate of 196.5 mA g^-1. Conversely, the electrochemical performance of silicaNQ@C exhibits an initial capacity of 705 mAh g^-1 and a 14% capacity increase after 200 cycles of testing at the same current rate. In conclusion, the innovative utilization of CNCs for synthesizing high-value materials, such as silicaNQs and their carbon-coated counterparts, demonstrates their versatility to be employed in various application areas.

Morteza Sabet

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