High‐power sodium–ion batteries capable of charging and discharging rapidly and durably are eagerly demanded to replace current lithium–ion batteries. However, poor activity and instable cycling of common sodium anode materials represent a huge barrier for practical deployment. A smart design of ordered nanotube arrays of iron oxide (Fe2O3) is presented as efficient sodium anode, simply enabled by surface sulfurization. The resulted heterostructure of oxide and sulfide spontaneously develops a built‐in electric field, which reduces the activation energy and accelerates charge transport significantly. Benefiting from the synergy of ordered architecture and built‐in electric field, such arrays exhibit a large reversible capacity, a superior rate capability, and a high retention of 91% up to 200 cycles at a high rate of 5 A g−1, outperforming most reported iron oxide electrodes. Furthermore, full cells based on the Fe2O3 array anode and the Na0.67(Mn0.67Ni0.23Mg0.1)O2 cathode deliver a specific energy of 142 Wh kg−1 at a power density of 330 W kg−1 (based on both active electrodes), demonstrating a great potential in practical application. This material design may open a new door in engineering efficient anode based on earth‐abundant materials.

Antimony (Sb) is a promising anode material for sodium‐ion batteries owing to its large capacity of 660 mAh g−1. However, its practical application is restricted by the rapid capacity decay resulted from a large volume expansion up to 390% upon Na alloying. Herein, construction of a self‐supported Sb array that has enough space allowing for effective accommodation of the volume change is reported. The array of Sb prisms is directly grown on a Cu substrate via a template‐free electrodeposition, followed by mild heating to consolidate the structural integrity between Sb and Cu. The resulting 3D architecture endows the Sb array with excellent sodium storage performance, exhibiting a reversible capacity of 578 mAh g−1 and retaining 531 mAh g−1 over 100 cycles at 0.5 C. The potential of Sb array in sodium‐ion full cells by pairing it with a Na0.67(Ni0.23Mg0.1Mn0.67)O2 cathode is further demonstrated. This full cell affords a specific energy of 197 Wh kg−1 at 0.2 C and a specific power of 1280 W kg−1 at 5 C. Considering its low cost and scale‐up capability, the template‐free route may find extensive applications in designing electrode architectures.

Sodium-ion batteries have attracted widespread attention for cost-effective and large-scale electric energy storage. However, their practical deployment has been largely retarded by the lack of choice of efficient anode materials featuring large capacity and electrochemical stability and robustness. Herein, we report a durian-inspired design and template-free fabrication of a robust sodium anode based on triangular pyramid arrays of Bi0.75Sb0.25 alloy electrodeposited on Cu substrates. The Bi0.75Sb0.25 arrays exhibit an appreciable electrochemical robustness for sodium storage, sustaining a reversible capability 335 mAh g–1 at a high rate of 2.5 A g–1 and 87% of the initial capacity over 2000 cycles. We further demonstrate the applicability of the Bi0.75Sb0.25 array anode in sodium full cells by pairing it with a Na3V2(PO4)3/C cathode. This full cell achieves a high specific energy of 203 Wh kg–1 (based on both active electrodes). Such an enhanced performance is attributed to the thorny-durian-like architecture and bimetallic alloy composition. The pyramid tip induces ion enrichment for rapid charge-transfer reaction, while the alloy design reduces the electrode volume swelling for stable Na cycling.

Rechargeable batteries with flexibility can find tremendous applications in wearable and bendable electronics. One central mission for the advancement of such high‐performance batteries is the exploration of flexible anodes with electrochemical and mechanical robustness. Herein reported is a robust and flexible sodium‐ion anode based on self‐supported hematite nanoarray grown on carbon cloth. The ammonia treatment that results in dual doping of both nitrogen and low‐valent iron renders surface reactivity and electric conductivity to the material. The dual‐doped hematite arrays afford a robust activity for sodium storage, exhibiting reversible capacities of 895 and 382 mAh g−1 at current rates of 0.1 and 5 A g−1, respectively, or 615 and 356 mAh g−1 by removing the contribution of the substrate. They also sustain 85% of the initial capacity upon 200 cycles at 0.2 A g−1. To demonstrate the flexibility, full cells composed of a hematite array anode and Na3V2(PO4)3/C cathode are assembled. The cell is capable of affording an energy density of 201 Wh kg−1 and sustaining repeated bending without performance decay, demonstrating a significant potential in practical application.

Molybdenum trioxide (MoO 3 ) has been considered as an appealing choice of anode for sodium-ion batteries because of its high theoretical capacity (1117 mA h g −1 ). However, the large volume change upon Na + storage results in poor cycling stability and capacity fade of MoO 3 . Here, we demonstrate a surface phosphorylation strategy to mitigate the degradation of three-dimensional MoO 3 array electrodes. Such a phosphorylation strategy allows MoO 3 arrays to sustain a capacity of 265 mA h g −1 , or ∼90% of the initial value, at a rate of 2 A g −1 over 1500 cycles, outperforming most reported MoO 3 electrodes. Moreover, kinetic analysis unveils a capacitance-dominated Na + storage feature of MoO 3 arrays, owing to the enhanced electron mobility imparted by oxygen vacancies that are simultaneously introduced by phosphorylation. Hence, surface phosphorylation might offer new possibilities to bypass multiple materials challenges facing current sodium electrodes.