Fast-kinetic multivalent ion storage enabled by multiscale structural modulation in two-dimensional magnetic...

Rechargeable multivalent ion batteries represent a promising avenue for high-energy-density storage; however, their practical application is plagued by sluggish multivalent ion diffusion kinetics in the host materials. Here we propose a multiscale structural modulation strategy based on two-dimensional magnetic materials to enhance the multivalent ion storage kinetics. Using two-dimensional ferromagnetic Ti_0.6Fe_0.4O₂ nanosheets as a model system, we show that Fe-induced spin-polarized interactions reduce the surface migration barrier of the multivalent ions, improving the microscopic transport kinetics; meanwhile, the ferromagnetism enables magnetic-field-induced assembly of vertically aligned, low-tortuosity nanosheet electrodes that shorten the mesoscopic diffusion pathways. This strategy accelerates multivalent-ion migration, enabling nonaqueous Mg- and Al-ion batteries to achieve specific powers of ~18.2 and 15.7 kW kg^-1 based on electrodes, nearly two orders of magnitude higher than those of state-of-the-art multivalent batteries. This strategy can be extended to various two-dimensional magnetic materials, thereby providing a potentially universal methodology in designing fast-kinetic multivalent-ion batteries.