Si Single-Atom Sites Anchored Carbon Anode Achieving the Zero-Strain Feature and Superior Li⁺ Storage Performance

Overcoming the significant volume strain in silicon-based anodes has been the focus of research for decades. The strain/stress in silicon-based anodes is inversely proportional to their size. In this study, we design atomic Si sites to achieve the ultimate size effect, which indeed exhibits a zero-strain feature. Compared with conventional silicon-based anodes with alloying addition reactions, the lithium-ion storage mechanism of atomic Si sites is solid-solution reactions, which brings about the zero-strain feature. Additionally, the ligand structure of atomic Si sites remains constant during cycling. This zero-strain feature results in excellent cycling stability. Furthermore, the exposed atomic Si sites enhance the electrochemical reaction kinetics, leading to outstanding rate performance. Moreover, the anode inherits the advantages of silicon-based anodes, including a low working voltage (~0.21 V) and high specific capacity (~2300 mAh g^-1 or ~1203 mAh cm^-3). This work establishes a novel pathway for designing low/zero-strain anodes.