Synthesis, Characterization, and Electromagnetic Wave Absorption Properties of Composites of Reduced Graphene Oxide with Porous LiFe₅O₈ Microspheres

A novel three-dimensional composite of reduced graphene oxide sheets and porous LiFe₅O₈ microspheres was fabricated via a facile, green, and highly tunable strategy, and the microstructure, composition, and microwave-absorbing performances of the rGO/porous LiFe₅O₈ composite were characterized and investigated. The experimental results indicate that the porous LiFe₅O₈ microspheres are dispersed on the thin rGO sheets uniformly. Compared with the pure LiFe₅O₈ particles and porous LiFe₅O₈ microspheres, the as-prepared rGO/porous LiFe₅O₈ composites exhibit outstanding microwave-absorbing performances including efficient bandwidth and reflection loss. The rGO/porous LiFe₅O₈ composite (S-50) displays a maximum reflection loss of −53.4 dB at 12.2 GHz with a coating layer thickness of 2.2 mm and a broad effective bandwidth of 3.5 GHz (from 10.4 to 13.9 GHz). The outstanding microwave-absorbing performances are assigned to employing magnetic microflowers with multi-interfaces to improve impedance matching, which is ascribed to strong relaxation loss, electrical loss, and magnetic loss. This further confirms that the rGO/porous LiFe₅O₈ composites could be potential candidates for lightweight microwave-absorbing materials

Facile Synthesis of Flowerlike LiFe₅O₈ Microspheres for Electrochemical Supercapacitors

Facile synthesis of porous and hollow spinel materials is very urgent due to their extensive applications in the field of energy storage. In present work, flowerlike porous LiFe₅O₈ microspheres etched for 15, 30, and 45 min (named as p-LFO-15, p-LFO-30, and p-LFO-45, respectively) are successfully synthesized through a facile chemical etching method based on bulk LiFe₅O₈ (LFO) particles as precursors, and they are applied as electrode materials for high-performance electrochemical capacitors. In particular, the specific surface area of p-LFO-45 reaches 46.13 m² g^–1, which is 112 times greater than that of the unetched counterpart. Therefore, the p-LFO-45 electrode can achieve a higher capacitance of 278 F g^–1 at a scan rate of 5 mV s^–1 than the unetched counterpart. Furthermore, the p-LFO-45 electrode presents a good cycling stability with 78.3% of capacitive retention after 2000 cycles, which is much higher than that of the unetched LFO particles (66%). Therefore, the flowerlike porous LFO microspheres are very promising candidate materials for supercapacitor applications