Hierarchically porous graphite particles are synthesized using a continuous, scalable aerosol approach. The unique porous graphite architecture provides the particles with high surface area, fast ion transportation, and good electronic conductivity, which endows the resulting supercapacitors with high energy and power densities. This work provides a new material platform for high-performance supercapacitors with high packing density, and is adaptable to battery electrodes, fuel-cell catalyst supports, and other applications.

In this study, we investigated the structural effect of composite solid electrolytes of Al-doped LLZO and PVDF-HFP (0D_Al-LLZO@PVDF-HFP and 1D_Al-LLZO@PVDF-HFP) on electrochemical (EC) performance and fire safety through a systematic evaluation and comparative tests. The unique structure and advantageous features of composite solid electrolytes (1D_Al-LLZO@PVDF-HFP) were highlighted by comparing controls (PVDF-HFP and 0D_Al-LLZO@PVDF-HFP) with physicochemical and electrochemical analyses and fire safety tests The structure and morphology of Al-doped LLZO/PVDF-HFP composites were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM), while their chemical functionalities and free ion clusters were examined with Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, respectively. The 1D_Al-LLZO@PVDF-HFP composite with a 1D structured Al-LLZO filler network in the PVDF-HFP matrix could effectively regulate the crystallinity of PVDF-HFP and facilitated lithium salt dissociation, resulting in a high lithium-ion transference number and ionic conductivity. As a result, the 1D_Al-LLZO@PVDF-HFP composite electrolyte with an optimized structure and low Al-LLZO content (~5.1 wt%) exhibited enhanced ionic conductivity (σ: 1.40 × 10^-4 S/cm) with low interfacial resistance, broadened EC stability (voltage window: 4.75 V vs. Li/Li⁺), and a high lithium-ion transference number (0.75) superior to that of 0D_Al-LLZO@PVDF-HFP. In electrochemical characterizations, the 1D_Al-LLZO@PVDF-HFP-based EC cell demonstrated enhanced performance in a lithium symmetric cell (>2000 h) and full cell (LiFePO₄|electrolyte|Li) of a reversible capacity of 102.7 mAh/g at 2C with a capacity retention of 85.7% over 200 cycles, better than that of a 0D_ Al-LLZO@PVDF-HFP-based EC cell. In flammability tests, Al-LLZO@PVDF-HFP demonstrated enhanced fire safety (nonflammability) compared with that of a PVDF-HFP-based electrolyte regardless of the composite structure, suggesting the importance of inorganic filler rather than their structural morphology in the composite.