Yuxiao Ma

Polyhedral-Like NiMn-Layered Double Hydroxide/Porous Carbon as Electrode for Enhanced Electrochemical Performance Supercapacitors

Polyhedral-like NiMn-layered double hydroxide/porous carbon (NiMn-LDH/PC-x) composites are successfully synthesized by hydrothermal method (x = 1, 2 means different mass percent of porous carbon (PC) in composites). The NiMn-LDH/PC-1 composites possess specific capacitance 1634 F g-1 at a current density of 1 A g-1 , and it is much better than that of pure LDH (1095 F g-1 at 1 A g-1 ). Besides, the sample can retain 84.58% of original capacitance after 3000 cycles at 15 A g-1 . An asymmetric supercapacitor with NiMn-LDH/PC-1 as anode and activated carbon as cathode is fabricated, and the supercapacitor can achieve an energy density of 18.60 Wh kg-1 at a power density of 225.03 W kg-1 . The enhanced electrochemical performance attributes to the high faradaic pseudocapacitance of NiMn-LDH, the introduction of PC, and the 3D porous structure of LDH/PC-1 composites. The introduction of PC hinders serious agglomeration of LDH and further accelerates ions transport. The encouraging results indicate that these materials are one of the most potential candidates for energy storage devices.

Ultralight Interconnected Graphene–Amorphous Carbon Hierarchical Foam with Mechanical Resiliency for High Sensitivity and Durable Strain Sensors

Ultralight graphene-amorphous carbon (AC) hierarchical foam (G-ACHF) was synthesized by chemical vapor deposition at 1065 °C, close to the melting point of copper. The high temperature leads to the hierarchical structure with an inner layer of graphene and an outer layer of AC. The inner graphene layer with high conductivity and integrity provides high sensitivity. The outer AC layer helps to enhance its durability and mechanical resiliency. The hierarchical structure recovers without damaging the structural integrity after a large strain of 90%. The electrical resistance of G-ACHF remains stable after 200 cycles of compression to a strain level of 50%. The fluctuation of the resistance value remains within ±3%, showing its stability in sensing performance. The pressure sensitivity of G-ACHF reaches as high as ∼11.47 Pa-1. Finite element simulation reveals that the stress borne by the key position of G-ACHF is 47% lower than that of graphene foam without the AC layer, proving that the AC layer can disperse the stress effectively. With a very low density of 1.17 × 10-3 g cm-1, the reversibly compressible G-ACHF strain sensor material exhibits its promising application potential in lightweight and wearable devices.