Ultralong K0.5Mn0.75PS3 Nanowires Tailored by K-Ion Scissors for Extraordinary Sodium-Ion Storage.

1D layered nanowires (NWs) are expected to be excellent electrode materials due to their efficient electron/ion transport and strain/stress relaxation. However, it is a great challenge to synthesize layered NWs by a top-down synthetic route. Herein, ultralong 1D layered K0.5Mn0.75PS3 NWs (length: >100 µm; diameter: ≈300 nm) are synthesized for the first time using "K-ion chemical scissors", whose excellent sodium storage performance originates from the bifunctional structural unit, ingeniously combining the alloying energy storage functional unit (P-P dimer) with the quasi-intercalated functional unit ([MnS3]4- framework). Stress-driven K-ion scissors achieve the rapid transformation of MnPS3 bulk to K0.5Mn0.75PS3 NWs with directed tailoring. Compared to MnPS3, the NWs exhibit enlarged interlayer spacing (9.32 Å), enhanced electronic conductivity (8.17 × 10-5 S m-1 vs 4.47 × 10-10 S m-1), and high ionic conductivity (2.14 mS cm-1). As expected, the NWs demonstrate high capacity (709 mAh g-1 at 0.5 A g-1) and excellent cycling performance (≈100% capacity retention after 2500 cycles at 10 A g-1), ranking among metal thiophosphates. A quasi-topological intercalation mechanism of the NWs is revealed through further characterizations. This work expands the top-down synthesis approach and offers innovative insights for the cost-effective and large-scale fabrication of NWs with outstanding electrochemical performance.

GeV4S8: a Novel Bimetallic Sulfide for Robust and Fast Potassium Storage.

Potassium-ion batteries (PIBs) have attracted much attention due to their low production cost and abundant resources. Germanium is a promising alloying-type anode with a high theoretical capacity for PIBs, yet suffering significant volume expansion and sluggish potassium-ion transport kinetics. Herein, a rational strategy is formulated to disperse Ge atoms into transition metal V-S sulfide frameworks to form a loosely packed and metallic GeV4S8 medium. The theoretical prediction shows that GeV4S8 is conducive to the adsorption and diffusion of K+. The V-S frameworks provide fast ion/electron diffusion channels and also help to buffer the volume expansion during K+ insertion. In situ and ex situ characterizations manifest that KGe alloy clusters are constrained and dispersed by potassiated VS2 topological structure during discharging, and revert to the original GeV4S8 after charging. Consequently, as a novel anode for PIBs, GeV4S8 provides a high specific capacity of ≈400 mAh g-1 at 0.5 C, maintaining 160 mAh g-1 even at 12.5 C and ≈80% capacity after 1000 cycles at 5 C, superior to most of the state-of-the-art anode materials. The proposed strategy of combining alloy and intercalation dual-functional units is expected to open up a new way for high-capacity and high-rate anode for PIBs.

Near-Infrared Acceptors with Imide-Containing End Groups for Organic Solar Cells.

Near-infrared electron acceptors for organic solar cells (OSCs) mostly contain electron-withdrawing 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC) end groups, which can be modified by but limited to phenyl, thienyl, and naphthyl units with halogenated, methyl, and methyloxy substitution. In this work, we employed an imide-containing unit to construct a new IC end group, based on which a series of new electron acceptors were synthesized. The strong electron-deficient nature of imide units enables the new acceptors to show efficient intramolecular charge transfer and hence red-shifted absorption spectra compared to their IC counterparts. These new electron acceptors were applied to OSCs, providing efficiencies of over 17% with a low voltage loss of 0.52 eV. These results demonstrate that the new imide-containing end groups are promising fragments for the construction of near-infrared electron acceptors for high-performance OSCs.