Geometrically Polarized Transport in Wedge-Shaped Mesoporous Carbon: A New Paradigm for Sodium-Ion Storage

Abstract Overcoming the rate-capacity trade-off in hard carbon anodes, a key bottleneck for sodium-ion batteries, requires moving beyond the traditional focus on pore size. This work presents a micelle-solvent interfacial self-assembly strategy that fabricates carbon spheres with precisely tunable, radially converging wedge-shaped mesopores. The unique architecture, governed by dynamic curvature–modulated micelle fusion and growth mechanism, enables a transformative "ion pre-enrichment—confined desolvation—cluster storage" process for Na⁺. Wide pore segments (> 5 nm) serve as high-throughput ion pre-reservoirs, while adjacent narrowing channels (2–5 nm) generate strong nanoconfinement. This effect compresses solvation shells, drastically lowers the desolvation barrier, and fosters the formation of high-density sodium ion aggregates (AGGs), as confirmed by ex situ spectroscopy and molecular dynamics simulations. The optimally structured anode delivers an ultrahigh reversible capacity (658.5 mAh g⁻¹ at 0.1 A g⁻¹), exceptional long-term cycling stability (200.1 mAh g⁻¹ after 50,000 cycles at 20 A g⁻¹), and superior full-cell performance. By establishing a "pore geometry-kinetics matching" principle, this geometric regulation concept provides a universal framework for optimizing ion-storage behavior across various battery systems, thereby, accelerating the commercialization of SIBs for large-scale energy storage.