High-Entropy Transition Metal Phosphorus Trichalcogenides for Rapid Sodium Ion Diffusion.

High-entropy strategies are regarded as a powerful means to enhance performance in energy storage fields. The improved properties are invariably ascribed to entropy stabilization or synergistic cocktail effect. Therefore, the manifested properties in such multicomponent materials are usually unpredictable. Elucidating the precise correlations between atomic structures and properties remains a challenge in high-entropy materials (HEMs). Herein, atomic-resolution scanning transmission electron microscopy annular dark field (STEM-ADF) imaging and four dimensions (4D)-STEM are combined to directly visualize atomic-scale structural and electric information in high-entropy FeMnNiVZnPS3. Aperiodic stacking is found in FeMnNiVZnPS3 accompanied by high-density strain soliton boundaries (SSBs). Theoretical calculation suggests that the formation of such structures is attributed to the imbalanced stress of distinct metal-sulfur bonds in FeMnNiVZnPS3. Interestingly, the electric field concentrates along the two sides of SSBs and gradually diminishes toward the two-dimensional (2D) plane to generate a unique electric field gradient, strongly promoting the ion-diffusion rate. Accordingly, high-entropy FeMnNiVZnPS3 demonstrates superior ion-diffusion coefficients of 10-9.7-10-8.3 cm2 s-1 and high-rate performance (311.5 mAh g-1 at 30 A g-1). This work provides an alternative way for the atomic-scale understanding and design of sophisticated HEMs, paving the way for property engineering in multi-component materials.

Crowding Effect-Induced Zinc-Enriched/Water-Lean Polymer Interfacial Layer Toward Practical Zn-Iodine Batteries.

Although the meticulous design of functional diversity within the polymer interfacial layer holds paramount significance in mitigating the challenges associated with hydrogen evolution reactions and dendrite growth in zinc anodes, this pursuit remains a formidable task. Here, a large-scale producible zinc-enriched/water-lean polymer interfacial layer, derived from carboxymethyl chitosan (CCS), is constructed on zinc anodes by integration of electrodeposition and a targeted complexation strategy for highly reversible Zn plating/stripping chemistry. Zinc ions-induced crowding effect between CCS skeleton creates a strong hydrogen bonding environment and squeezes the moving space for water/anion counterparts, therefore greatly reducing the number of active water molecules and alleviating cathodic I3- attack. Moreover, the as-constructed Zn2+-enriched layer substantially facilitate rapid Zn2+ migration through the NH2-Zn2+-NH2 binding/dissociation mode of CCS molecule chain. Consequently, the large-format Zn symmetry cell (9 cm2) with a Zn-CCS electrode demonstrates excellent cycling stability over 1100 h without bulging. When coupled with an I2 cathode, the assembled Zn-I2 multilayer pouch cell displays an exceptionally high capacity of 140 mAh and superior long-term cycle performance of 400 cycles. This work provides a universal strategy to prepare large-scale production and high-performance polymer crowding layer for metal anode-based battery, analogous outcomes were veritably observed on other metals (Al, Cu, Sn).

Interfacial Protection Engineering of Sodium Nanoparticles toward Dendrite-Free and Long-Life Sodium Metal Battery.

The instability of interfacial solid-electrolyte interphase (SEI) layer of metallic sodium (Na) anode during cycles results in the rapid capacity decay of sodium metal batteries (SMBs). Herein, the concept of interfacial protection engineering of Na nanoparticles (Na-NPs) is proposed first to achieve stable, dendrite-free, and long-life SMB. Employing an ion-exchange strategy, conformal Sn-Na alloy-SEI on the interface of Na-NPs is constructed, forming Sn@Na-NPs. The stable alloy-based SEI layer possesses the following three advantages: 1) significantly enhancing the transport dynamics of Na+ ions and electrons; 2) enabling the well-distributed deposition of Na+ ions to avoid the growth of dendrites; and 3) protecting the Sn@Na-NPs anode from the attack of electrolyte, thereby reducing the parasitic reaction and boosting the Coulombic efficiency of SMBs. Because of these virtues, the symmetric Sn@Na-NPs cell shows an ultralow voltage hysteresis of 0.54 V at 10 mA cm-2 after 600 h. Paired with the Na3 V2 (PO4 )2 O2 F (NaVPF) cathode, the NaVPF-Sn@Na-NPs full cell exhibits an initial discharge capacity of 89.2 mAh g-1 at 1 C and a high capacity retention of 81.6% after 600 cycles.