SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4369-1
Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries for large-scale energy storage due to sodium's abundance and low cost. Among cathode materials, polyanionic compounds like Na3V2(PO4)2O2F (NVPOF) offer high energy density and dual voltage plateaus at ~3.6 and 4.0 V, but suffer from low electronic conductivity and sluggish Na+ diffusion. Here, we report a dual-modulation strategy combining high-valence Nb5+ doping and polydopamine-derived carbon coating to synthesize Na3V1.94Nb0.06(PO4)2O2F-C (NVPOF-Nb-C) via a hydrothermal route. X-ray diffraction and Rietveld refinement confirm that Nb5+ doping induces slight lattice expansion without altering the tetragonal I4/mmm framework. Density functional theory calculations reveal that Nb5+ doping optimizes the crystal structure and reduces the Na+ diffusion barrier, while the uniform carbon coating enhances electron transport. Consequently, NVPOF-Nb-C exhibits remarkably improved electrochemical performance, including high reversible capacity, excellent rate capability, and ultralong cycling stability. In a full cell with hard carbon anode, it delivers a high energy density of 487.2 Wh kg−1 at 1C and retains 91.51% capacity after 3000 cycles at 20C. This work provides a synergistic strategy to overcome the intrinsic limitations of polyanionic cathodes for practical SIB applications.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3746-x
The polyanionic compound Na3V2(PO4)2O2F (NVPOF) possesses a stable three-dimensional framework, high theoretical specific capacity, and favorable operating voltage, yet its sluggish Na+ diffusion kinetics and low electronic conductivity impede industrial application. This study proposes a dual regulation strategy combining carbon coating and heat treatment temperature to synergistically enhance crystallinity and electrochemical performance. NVPOF@C-400 and NVPOF@C-600 were synthesized via in-situ dopamine hydrochloride coating followed by heat treatment at 400 °C and 600 °C, respectively. Carbon coating at 600 °C significantly improved crystallinity and increased electronic conductivity by three orders of magnitude through the carbon layer's conductive network. The ~4.5 nm carbon layer effectively suppressed abnormal grain growth and secondary crystallization aggregation at high temperatures, maintaining uniform particle size of approximately 0.36 μm, which shortens Na+ diffusion pathways and prevents ion transport obstruction. Consequently, NVPOF@C-600 delivered a high discharge capacity of 102.5 mAh g−1 at 20 C and retained 96.5% capacity after 10,000 cycles. In a full-cell configuration with hard carbon (HC), NVPOF@C-600//HC achieved an impressive 89.3% capacity retention after 9,000 cycles. This work provides critical insights for practical implementation of high-performance NVPOF cathodes in sodium-ion batteries.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-024-3358-1
Type II photosensitizers (PSs) activated by 660 nm light suffer from high oxygen consumption, limiting efficacy in hypoxic microenvironments. Type I PSs triggered by 808 nm near-infrared (NIR) light enable electron transfer to generate superoxide anions (O2•−) with lower oxygen dependence. However, developing type I PSs remains challenging due to the low energy of NIR light and the intrinsic preference for type II processes under matched energy levels. Here, co-assembly of 5,10,15,20-tetrakis-(4-aminophenyl)-porphyrin (TAPP) with N-carbobenzyloxy-L-leucine (Cbz-Leu) yields a supramolecular nano-PS (TAPP@Cbz-Leu). Under 808 nm irradiation, TAPP@Cbz-Leu significantly produces O2•−. Noncovalent tight binding between TAPP and Cbz-Leu enhances photoinduced electron transfer from Cbz-Leu to triplet TAPP, generating TAPP•− and promoting O2•− formation. TAPP@Cbz-Leu also exhibits excellent photothermal properties under 808 nm irradiation, with a photothermal conversion efficiency of 32.7%. In vivo studies demonstrate effective antibacterial activity against MRSA-infected wound models and accelerated wound healing. This work represents the first example of converting a type II PS into a type I PS via a simple co-assembly strategy, offering a new paradigm for NIR-triggered supramolecular type I photosensitizers.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3385-4
Two-dimensional transition metal carbides/nitrides (MXenes) exhibit exceptional mechanical and electrical properties, positioning them as promising candidates for electronics, aerospace, and energy storage. However, assembling MXene nanosheets into high-performance macroscopic nanocomposites remains challenging due to low stress-transfer efficiency between nanosheets. This review systematically examines the role of voids within MXene-based nanocomposites, revealing that voids can paradoxically enhance performance under specific conditions. We discuss strategies to mitigate detrimental voids, including synergistic interfacial interactions, nanosheet filling, fabrication process optimization, and nanoconfined assembly. Empirical data from referenced studies indicate that void content critically influences mechanical reinforcement; for instance, graphene oxide monolayers exhibit a Young's modulus of approximately 200 GPa, while MXene monolayers reach 330 GPa. The review also highlights that controlled nanovoid dispersion in metals can increase strength by up to 50% without sacrificing ductility. We provide a roadmap for fabricating high-performance MXene-based nanocomposites, emphasizing the need to balance void elimination with intentional void engineering. This work consolidates current understanding and identifies pathways to overcome the stress-transfer bottleneck, enabling scalable production of MXene composites with tailored properties for demanding applications.