Jian Jiang

Room-temperature sodium–sulfur batteries (RT Na–S) hold great potential for energy storage due to the abundance of sodium and sulfur, low costs, and high theoretical energy density. However, their development is limited by the shuttle effect of polysulfides, slow reaction kinetics, and the growth of sodium dendrites. These issues lead to rapid capacity decay and poor cycling stability, which are difficult to mitigate using traditional separators. Inspired by ion channels in biological membranes, we developed a carboxylate-modified MIL-121/Na separator. Its sub-nanometer channels enable highly selective Na⁺ transport with an ionic conductivity of 2.27 × 10⁻⁴ S cm⁻¹, a migration number of 0.74, and a wide electrochemical window of up to 5.1 V. When applied in RT Na–S batteries, it effectively inhibits the polysulfide shuttle and promotes the reaction kinetics, achieving a first-cycle discharge capacity of 1182 mAh g⁻¹ at a 0.5C rate and stable cycling for over 400 cycles, demonstrating excellent rate performance and long cycle life. Even in pouch cells, the performance can be stabilized at a 1C rate for 100 cycles and the cycle-to-cycle stability can be maintained. This study provides a new strategy for separator design to advance high-performance sodium–sulfur batteries.

Rechargeable Fe‐ion batteries with overwhelming cost/environmental benign superiorities hold great promise in large‐scale charge‐storage applications. However, there is still a lack of competitive cathodes with prominent capacity and long‐term cyclability. To overcome these constraints, a unique Fe²⁺/NH₄⁺ co‐insertion strategy is proposed, enabling both doubled reversible capacity and cyclic life of Berlin green (FeHCF) cathodes. The Fe²⁺ insertion proves to induce FeHCF lattice contractions, alter ligand environment/activation energies of low‐spin Fe^III, and hence boost the redox conversion depth, while NH₄⁺ co‐insertions help to elevate the cathode capacities by utilizing Fe²⁺‐unoccupied reaction sites. Besides, they generate hydrogen bonds between inserted NH₄⁺ ions and N atoms in FeHCF, capable of vastly strengthening the cathode's cyclic durability. Cathodes in such collaborative dual‐cation electrolytes exhibit a remarkable capacity of 162 mAh g⁻¹ (4 A g⁻¹) and far prolonged operation lifespan (over 1000 cycles) when compared to single‐cation cases. The assembled full cells demonstrate impressive energy densities up to 70.4 Wh kg⁻¹, and far superior capacity retention of 88% after all the cycling. This work may offer a simple/feasible, and effective route to render high‐capacity and long‐lasting cathodes for future/practical Fe‐ion battery systems.

LiFe_1−xMn_xPO₄ with elevated energy density is becoming the next-generation olivine-type cathode.

Intrinsically weak metal affinity and sluggish sodium (Na) nucleation/molten fluidic transport of conventional hosts impede the fabrication of high‐capacity Na anodes. Mediating surface free energies (SFEs) of hosts and reinforcing their intermolecular attraction to viscous Na fluids can radically solve these problems. Herein, “canaled” tin oxide nanorod arrays grown on a 3D carbon cloth (CC) matrix exhibit distinct polar/nonpolar SFE components that markedly elevate the solid–liquid wettability for molten Na is reported. Such nanocanal defects render strong capillary forces for spontaneous molten Na imbibition and help to instantly activate Na─Sn alloying and Na nucleation reactions. Furthermore, sodiophilic Na₁₅Sn₄ interlayers evolved in former alloying procedures also aid in reducing Na nucleation energy barriers and guide the planar electro‐deposition/dispersion, alleviating the uncontrolled Na dendrite growth. The derived Na/Na₁₅Sn₄/CC anodes can thus keep stable after 2000 h of galvanostatic cycling at 1 mA cm⁻² or high‐rate testing, without notable dendritic formation. The packed full cells also show superior rate capability and cyclability (capacity retention over 91.5% after all cycling at 1 C). This work provides a smart nano‐engineering way to trigger a fast infusion of molten metals into hosts and synergistically facilitate Na fluidic transport, which may push forward the scalable application of Na metal batteries.

Metal‐ion capacitors could merit advantages from both batteries and capacitors, but they need to overcome the severe restrictions from their sluggish reaction kinetics of the battery type electrode and low specific capacitance of capacitor type electrode for both high energy and power density. Herein, we use the Kirkendall effect for the first time to synthesize unique tubular hierarchical molybdenum dioxide with encapsulated nitrogen‐doped carbon sheets while in situ realizing phosphorus‐doping to create rich oxygen vacancies (P‐MoO_2‐x@NP‐C) as a sodium‐ion electrode. Experimental and theoretical analysis confirm that the P‐doping introduced oxygen defects can partially convert the high‐bond‐energy Mo–O to low‐bond‐energy Mo–P, resulting in a low oxidation state of molybdenum for enhanced surface reactivity and rapid reaction kinetics. The as‐prepared P‐MoO_2‐x@NP‐C as an ion‐battery electrode is further used to pair active N‐doped carbon nanosheet (N‐C‐A) electrode for Na‐ion hybrid capacitor, delivering excellent performance with an energy density of 140.3 Wh kg⁻¹, a power density of 188.5 W kg⁻¹ and long stable life in non‐aqueous solution, which ranks the best among all reported MoO_x‐based hybrid capacitors. P‐MoO_2‐x@NP‐C is also used to fabricate a zinc‐ion hybrid capacitor, also accomplishing a remarkable energy density of 43.8 Wh kg⁻¹, a power density of 93.9 W kg⁻¹, and a long stable life@2A g⁻¹ of 32 000 cycles in aqueous solutions, solidly verifying its universal significance. This work not only demonstrates an innovative approach to synthesize high‐performance metal ion hybrid capacitor materials but also reveals certain scientific insights into electron transfer enhancement mechanisms.

Thermotolerant and Li ₂ S _n -trapped/converted separators are enabled by NiFe ₂ O ₄ quantum dots/g-C ₃ N ₄ nanofiber interlayers for more practical Li–S batteries.