Hard carbons attract myriad interest as anode materials for high-energy rechargeable batteries due to their low costs and high theoretical capacities; practically, they deliver unsatisfactory performance due to their intrinsically disordered microarchitecture. Here we report a facile ion-catalyzed synthesis of a phenol-formaldehyde resin-based hard-carbon aerogel that takes advantage of the chelation effect of phenol and Fe, which consists of a three-dimensionally interconnected carbon network embedded with hydrogen-rich, ordered microstructures of expanded nanographites and carbon micropores. The chelation effect ensures the homodispersion of Fe in the polymer segments of the precursor, so that an effective catalytic conversion from sp to sp carbon occurs, enabling free rearrangement of graphene sheets into expanded nanographite and carbon micropores. The structural merits of the carbon offer chances to achieve lithium/sodium storage performance far beyond that possible with the conventional carbon anode materials, including graphite and mesocarbon microbeads, along with fast kinetics and long cycle life. In this way, our hard carbon proves its feasibility to serve as an advanced anode material for high-energy rechargeable Li/Na batteries.

All-inorganic CsPbI 3 perovskite presents preeminent chemical stability and a desirable band gap as the front absorber for perovskite/silicon tandem solar cells. Unfortunately, CsPbI 3 perovskite solar cells (PSCs) still show low efficiency due to high density of defects in solution-prepared CsPbI 3 films. Herein, three kinds of hydrazide derivatives (benzoyl hydrazine (BH), formohydrazide (FH) and benzamide (BA)) are designed to reduce the defect density and stabilize the phase of CsPbI 3 . Calculation and characterization results corroborate that the carboxyl and hydrazine groups in BH form strong chemical bonds with Pb 2 + ions, resulting in synergetic double coordination. In addition, the hydrazine group in the BH also forms a hydrogen bond with iodine to assist the coordination. Consequently, a high efficiency of 20.47 % is achieved, which is the highest PCE among all pure CsPbI 3 -based PSCs reported to date. In addition, an unencapsulated device showed excellent stability in ambient air.Since a cesium lead iodide (CsPbI 3 ) perovskite solar cell (PSC) was first reported in 2015, CsPbI 3 perovskite has attracted great interest due to its excellent chemical stability and appropriate band gap ( � 1.7 eV) as the front sub-cell active layer for tandem solar cells. [1][2][3] Regrettably, the highest power conversion efficiency (PCE) of CsPbI 3 -based

The application of ionic liquids in perovskite has attracted wide-spread attention for its astounding performance improvement of perovskite solar cells (PSCs). However, the detailed mechanisms behind the improvement remain mysterious. Herein, a series of imidazolium-based ionic liquids (IILs) with different cations and anions is systematically investigated to elucidate the passivation mechanism of IILs on inorganic perovskites. It is found that IILs display the following advantages: (1) They form ionic bonds with Cs+ and Pb2+ cations on the surface and at the grain boundaries of perovskite films, which could effectively heal/reduce the Cs+/I− vacancies and Pb-related defects; (2) They serve as a bridge between the perovskite and the hole-transport-layer for effective charge extraction and transfer; and (3) They increase the hydrophobicity of the perovskite surface to further improve the stability of the CsPbI2Br PSCs. The combination of the above effects results in suppressed non-radiative recombination loss in CsPbI2Br PSCs and an impressive power conversion efficiency of 17.02%. Additionally, the CsPbI2Br PSCs with IILs surface modification exhibited improved ambient and light illumination stability. Our results provide guidance for an in-depth understanding of the passivation mechanism of IILs in inorganic perovskites."Image missing"

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