Sodium (Na) is the most appealing alternative to lithium as an anode material for cost‐effective, high‐energy‐density energy‐storage systems by virtue of its high theoretical capacity and abundance as a resource. However, the uncontrolled growth of Na dendrites and the limited cell cycle life impede the large‐scale practical implementation of Na‐metal batteries (SMBs) in commonly used and low‐cost carbonate electrolytes. Herein, the employment of a novel bifunctional electrospun nanofibrous separator comprising well‐ordered, uniaxially aligned arrays, and abundant sodiophilic functional groups is presented for SMBs. By tailoring the alignment degree, this unique separator integrates with the merits of serving as highly aligned ion‐redistributors to self‐orientate/homogenize the flux of Na‐ions from a chemical molecule level and physically suppressing Na dendrite puncture at a mechanical structure level. Remarkably, unprecedented long‐term cycling performances at high current densities (≥1000 h at 1 and 3 mA cm⁻², ≥700 h at 5 mA cm⁻²) of symmetric cells are achieved in additive‐free carbonate electrolytes. Moreover, the corresponding sodium–organic battery demonstrates a high energy density and prolonged cyclability over 1000 cycles. This work opens up a new and facile avenue for the development of stable, low‐cost, and safe‐credible SMBs, which could be readily extended to other alkali‐metal batteries.

Buckling-driven shape-shifting is increasingly being used in metamaterials to achieve mechanical programmability and novel functionality. Here, we show that the post-buckling response and the ensuing behavior, of lattice metamaterials can be programed through so-called passive and active modal nudging. Numerical continuation is first used to explore exhaustively the bifurcation manifold of a compressed, elastomeric lattice metamaterial. We then tailor the natural postcritical behavior of the metamaterial by judiciously altering the baseline geometry using modal information extracted from the bifurcation landscape (passive modal nudging). Experimental tests verify the effectiveness of the approach. Subsequently, shape change is induced by actively nudging the metamaterial between two stable postcritical states using an embedded actuator, i.e., by changing the local topology of the metamaterial rather than by controlling a global field. Fundamentally, we use passive modal nudging to bias the metamaterial towards one of three possible postcritical states under applied compression and then employ active nudging to switch between different postcritical states. Based on this paradigm, we manufacture and test a crawling soft robot and demonstrate that locomotion through local actuation to switch between two postcritical states is significantly more energy efficient than the alternative strategy of switching between a precritical and a postcritical state through global actuation. Overall, this paper demonstrates the benefits and promise of programming the behavior of soft metamaterials by exploiting principles of bifurcation theory and using tailored imperfections and embedded actuators.

We present here a design of the unit cell of a mechanical metamaterial based on the use of a tensegrity structural configuration with a metal rubber. Tensegrity combines the use of compression and tension-only elements, and allows the creation of structures with high rigidity per unit mass. Metal rubber is a multiscale porous metal material with high energy absorption and vibration damping capabilities under compressive load. The combination of the two structural and material concepts gives rise to a mechanical metamaterial with increased energy absorption and tuneable nonlinearity under quasi-static, vibration, and impact loading. We develop prototypes, models, and perform tests under static and dynamic loading conditions to assess the performance of this mechanical metamaterial.