Zhongqiang Shan

Silicon (Si) is a promising next-generation anode for high-energy-density lithium-ion batteries. The application of silicon/carbon (Si/C) composites with high Si content is hindered by the huge volume change and insecure electrochemical interface of the Si anode. Herein, chemical-expanded graphite (CEG) is used as a carbon matrix to form Si@CEG/C composites with an embedded structure. CEG with an abundant pore structure and electropositivity can well disperse and accommodate a mass of Si nanoparticles (Si NPs). With the flexibility and porosity of CEG, the embedded structure of Si NPs fixed in an expanded graphite layer can adopt the volume change of Si NPs and offer the abundant path of diffusion of lithium-ion, which leads to a moderate cycle and rate performance. Si@CEG/C exhibits a high reversible capacity of 1232.4 mA h g^-1 at a current density of 0.5 A g^-1 and with a capacity retention rate of 87% after 200 cycles. This embedded structure of Si/C composites built by CEG is meaningful for the structure design of the Si-based anode with higher specific capacity, active material utilization, and satisfactory cycle stability.

Limited by low electrical conductivity and huge volume changes in the process of lithium intercalation/de‐intercalation, the commercial application of Si‐based anode materials for lithium‐ion batteries is hindered. Herein, silicon nanoparticles embedded in nitrogen‐doped hard carbon microspheres composites (Si/NC@HC) were prepared by two‐step polymerization of 3‐aminophenol and resorcinol between formaldehyde and further carbonization. The formed double carbon matrix, including the inter NC microsphere and outer nanometer‐thick HC layer, can not only improve the electrical conductivity and silicon load but also ensure high structural stability to alleviate the volume effect of silicon effectively. Therefore, the obtained Si/NC‐2@HC possesses a high specific capacity of 1262.6 mAh g ⁻¹ after 300 cycles at the current density of 0.5 A g ⁻¹ with high silicon contents of 78 %, exhibiting excellent cycling performance. The novel synthesis method and structural design will provide a strategy for engineering Si‐based anode materials with high specific capacity and enhanced cycling performance.

BODIPY dyes have recently been used for photothermal and photodynamic therapy of tumors. However, complex multi-material systems, multiple excitation wavelengths and the unclear relationship between BODIPY structures and their PTT/PDT efficiency are still major issues. In our study, nine novel BODIPY near-infrared dyes were designed and successfully synthesized and then, the relationships between BODIPY structures and their PTT/PDT efficiency were investigated in detail. The results showed that modifications at position 3,5 of the BODIPY core with conjugated structures have better effects on photothermal and photodynamic efficiency than the modifications at position 2,6 with halogen atoms. Density functional theory (DFT) calculations showed that this is mainly due to the extension of the conjugated chain and the photoinduced electron transfer (PET) effect. By encapsulating BDPX-M with amphiphilic DSPE-PEG₂₀₀₀-RGD and lecithin, the obtained NPs not only show good water solubility and biological stability, but also could act as superior agents for photothermal and photodynamic synergistic therapy of tumors. Finally, we obtained BODIPY NPs that exhibited excellent photothermal and photodynamic effects at the same time under single irradiation with an 808 nm laser (photothermal conversion efficiency: 42.76%, A/A₀: ∼0.05). In conclusion, this work provides a direction to design and construct phototherapeutic nanoparticles based on BODIPY dyes for tumor treatment.

Graphite@Si encapsulated in carbon conformally coated tiny SiO₂nanoparticle matrix composites (G@Si/SiO₂NPs/C) were well-designed as anode materials for lithium-ion batteries, which show high specific capacity and remarkable cycling stability.

Dry coating of ultrastable Li₃V₂(PO₄)₃-carbon (LVP-C) nanoparticles on LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) leads to a robust composite cathode with improved rate capability and cycling life without sacrificing the specific energy density compared with pristine NCM622.

Dissolution and free diffusion of polysulfides in ether‐based electrolyte during cycling causes fast capacity decay and low columbic efficiency in lithium‐sulfur batteries. In this work, poly(2‐ethyl‐2‐oxazoline) (PEtOx), as an additive of sulfur cathodes, can gelatinate the electrolyte in the presence of polysulfide species, which can anchor the uncontrollable diffusion of polysulfides during the discharge process. Additionally, pore structures can form in the sulfur cathode after the dissolution of PEtOx into the electrolyte. As a result, the sulfur converted from polysulfides during subsequent charging processes will deposit more uniformly in the porous cathode. This “dissolution‐redeposition” mechanism effectively reduces the loss of active materials, providing beneficial guidance for practical Li−S batteries.

A network of graphene conductive stress buffer and poly-γ-glutamate binder via interparticle electrostatic and hydrogen bonding is constructed for an improved multifunctional Si nanocomposite anode of lithium-ion batteries.