3D Honeycomb Architecture Enables a High‐Rate and Long‐Life Iron (III) Fluoride–Lithium Battery

Metal fluoride–lithium batteries with potentially high energy densities, even higher than lithium–sulfur batteries, are viewed as very promising candidates for next‐generation lightweight and low‐cost rechargeable batteries. However, so far, metal fluoride cathodes have suffered from poor electronic conductivity, sluggish reaction kinetics and side reactions causing high voltage hysteresis, poor rate capability, and rapid capacity degradation upon cycling. Herein, it is reported that an FeF₃@C composite having a 3D honeycomb architecture synthesized by a simple method may overcome these issues. The FeF₃ nanoparticles (10–50 nm) are uniformly embedded in the 3D honeycomb carbon framework where the honeycomb walls and hexagonal‐like channels provide sufficient pathways for the fast electron and Li‐ion diffusion, respectively. As a result, the as‐produced 3D honeycomb FeF₃@C composite cathodes even with high areal FeF₃ loadings of 2.2 and 5.3 mg cm^?2 offer unprecedented rate capability up to 100 C and remarkable cycle stability within 1000 cycles, displaying capacity retentions of 95%–100% within 200 cycles at various C rates, and ≈85% at 2C within 1000 cycles. The reported results demonstrate that the 3D honeycomb architecture is a powerful composite design for conversion‐type metal fluorides to achieve excellent electrochemical performance in metal fluoride–lithium batteries.     

Pressure-Stabilized High-Entropy (FeCoNiCuRu)S2 Sulfide Anode toward Simultaneously Fast and Durable Lithium/Sodium Ion Storage

Pressure-stabilized high-entropy sulfide (FeCoNiCuRu)S₂ (HES) is proposed as an anode material for fast and long-term stable lithium/sodium storage performance (over 85% retention after 15 000 cycles @10 A g⁻¹). Its superior electrochemical performance is strongly related to the increased electrical conductivity and slow diffusion characteristics of entropy-stabilized HES. The reversible conversion reaction mechanism, investigated by ex-situ XRD, XPS, TEM, and NMR, further confirms the stability of the host matrix of HES after the completion of the whole conversion process. A practical demonstration of assembled lithium/sodium capacitors also confirms the high energy/power density and long-term stability (retention of 92% over 15 000 cycles @5 A g⁻¹) of this material. The findings point to a feasible high-pressure route to realize new high-entropy materials for optimized energy storage performance.