Fig. 1: Design rationale of mechano-kinetic integrated low-expansion silicon composite negative electrodes.

I Sieving-pore structures, due to size sieving effects at the pore entrance, allow Li⁺ and anions with partial solvents to enter the pores and participate in electrochemical reactions, thereby effectively suppressing side reactions and favoring the formation of inorganic-rich SEI within the pores. Meanwhile, Li⁺ can move smoothly through the pore entrance, and the resulting inorganic-rich SEI facilitates rapid Li⁺ conduction and mechanical confinement for the expansion of Si in pores, demonstrating mechanical stability and fast kinetics. II Closed-pore structures, in which the expanded/cracked Si core is protected by the closed shell, while the ion transport paths are blocked, deliver mechanical stability but sluggish kinetics. III Buried-pore structures, in which the Si surface is directly exposed to the electrolyte, and the structure tends to collapse during cycling, result in mechanical instability and long Li⁺ diffusion distances. IV Open-pore structures, in which the Si surface is directly exposed to the electrolyte, and porous structures shorten ion diffusion paths, yet the structure easily collapses during cycling, lead to mechanical instability but fast kinetics.