A Carbon Aerogel Lightweight Al Battery for Fast Storage of Fluctuating Energy.

Al batteries have great potential for renewable energy storage owing to their low cost, high capacity, and safety. High energy density and adaptability to fluctuating electricity are major challenges. Here, a lightweight Al battery for fast storage of fluctuating energy is constructed based on a novel hierarchical porous dendrite-free carbon aerogel film (CAF) anode and an integrated graphite composite carbon aerogel film (GCAF) cathode. A new induced mechanism by the O-containing functional groups on the CAF anode is con-firmed for uniform Al deposition. The GCAF cathode possesses a higher mass utilization ratio due to the extremely high loading mass (9.5-10.0 mg cm-2 ) of graphite materials compared to conventional coated cathodes. Meanwhile, the volume expansion of the GCAF cathode is almost negligible, resulting in better cycling stability. The lightweight CAF‖GCAF full battery can adapt well to large and fluctuating current densities owing to its hierarchical porous structure. A large discharge capacity (115.6 mAh g-1 ) after 2000 cycles and a short charge time (7.0 min) at a high current density are obtained. The construction strategy of lightweight Al batteries based on carbon aerogel electrodes can promote the breakthrough of high-energy-density Al batteries adapted to the fast storage of fluctuating renewable energy.

Novel (Pt-Ox )-(Co-Oy ) Nonbonding Active Structures on Defective Carbon from Oxygen-Rich Coal Tar Pitch for Efficient HER and ORR.

Atomic-scale utilization and coordination structure of Pt electrocatalyst is extremely crucial to decrease loading mass and maximize activity for hydrogen evolution reactions (HERs) and oxygen reduction reactions (ORRs). A novel atomic-scale (Pt-Ox )-(Co-Oy ) nonbonding active structure is designed and constructed by anchoring Pt single atoms and Co atomic clusters on the defective carbon derived from oxygen-rich coal tar pitch (CTP). The Pt loading mass is extremely low and only 0.56 wt%. A new nonbonding interaction phenomenon between Pt-Ox and Co-Oy is found and confirmed based on X-ray absorption spectroscopy and density functional theory calculations. Based on the (Pt-Ox )-(Co-Oy ) nonbonding active structure, surface chemical field coupling with electrocatalysis for the HER and ORR is confirmed. It is found that the (Pt-Ox )-(Co-Oy ) nonbonding active structure exhibits high mass activities of 64.4 A cm-2 mgPt -1 (at an overpotential of 100 mV) and 7.2 A cm-2 mgPt -1 (at 0.8 V vs reversible hydrogen electrode) for the HER and ORR, respectively. The values are 6.5 and 11.6 times as much as those of commercial 20% Pt/C. The work provides innovative insight to design and understand efficient active sites of atomic-scale Pt on oxygen-rich CTP-derived carbon supports for electrocatalysis.