Achieving stable Zn metal anode via a hydrophobic and Zn2+-conductive amorphous carbon interface.

High security and low cost enable aqueous zinc ion batteries (AZIBs) with huge application potential in large-scale energy storage. Nevertheless, the loathsome dendrite and side reactions of Zn anode are harmful to the cycling lifespan of AZIBs. Here, a new type of thin amorphous carbon (AC) interface layer (∼100 nm in thickness) is in-situ constructed on the Zn foil (Zn@AC) via a facile low-temperature chemical vapor deposition (LTCVD) method, which owns a hydrophobic peculiarity and a high Zn2+ transference rate. Moreover, this AC coating can homogenize the surface electric field and Zn2+ flux to realize the uniform deposition of Zn. Consequently, dendrite growth and side reactions are concurrently mitigated. Symmetrical cell achieves a dendrite-free Zn plating/stripping over 500 h with a low overpotential of 31 mV at 1 mA cm-2/1 mAh cm-2. Of note, the full cell with a MnO2/CNT cathode harvests a capacity retention of 70.0 % after 550 cycles at 1 A/g. In addition, the assembled flexible quasi-solid-state AZIBs display a stable electrochemical performance under deformation conditions and maintain a capacity of 76.5 mAh/g at 5 A/g after 300 cycles. This innovative amorphous carbon layer is expected to provide a new insight into stabilizing Zn anode.

The design and synthesis of new advanced energetic materials based on pyrazole-triazole backbones.

A series of derivatives of the nitropyrazole-triazole backbone were designed through units' screening of 219 N-heterocycle compounds and were synthesized. Among them, the thermal stability of DNPAT (Tdec = 314 °C) is close to that of traditional heat-resistant explosive HNS (318 °C) while the detonation performance and sensitivity (D = 8889 m s-1; IS = 18 J) are better than those of HNS (D = 7612 m s-1; IS = 5 J) and traditional high-energy explosive RDX (D = 8795 m s-1; IS = 7.4 J), which is rarely reported in heat-resistant explosives. Moreover, compounds 4 and 6 show excellent performances (IS > 15 J, D > 9090 m s-1, P > 37.0 GPa), illustrating that compounds 4 and 6 may be used as secondary explosives. All these results enrich prospects for the development of energetic materials.

An advanced primary explosive and secondary explosive based on a zwitterionic pyrazole-triazole derivative.

Two zwitterionic energetic materials containing a pyrazole-triazole backbone were synthesized and fully characterized. Compound 3 can serve as an ideal secondary explosive due to its high decomposition temperature (>200 °C), low impact sensitivity (>40 J), and excellent calculated detonation velocity (9090 m s-1). The good priming ability of compound 4 demonstrates that it is a potential candidate as a primary explosive, which was confirmed in the test. These results indicate that zwitterionic molecules are an efficient promising class for the future design of new high-energy density materials.

Combinations of furoxan and 1,2,4-oxadiazole for the generation of high performance energetic materials.

Several energetic materials, which are composed of furoxan and 1,2,4-oxadiazole backbones, were synthesized by nitrating 3,3'-bis(5-amino-1,2,4-oxadiazol-3-yl)-4,4'-azofuroxan (2) under 100 wt% HNO3 or 100 wt% HNO3/Ac2O followed by a cation metathesis. All synthesized compounds were fully characterized by multinuclear NMR spectroscopy, IR spectroscopy, and elemental analysis, while 3,3'-bis(1,2,4-oxadiazol-5(4H)-one-3-yl)-4,4'-azofuroxan (3) and diammonium 3,3'-bis(5-nitramino-1,2,4-oxadiazole-3-yl)-4,4'-azofuroxan (4a) were confirmed by single crystal X-ray diffraction. The physicochemical and energetic properties of these compounds including density, thermal stability and sensitivity were investigated. Compounds 3 and 4 have high densities (3: 1.90 g cm-3, 4: 1.92 g cm-3), which are comparable to that of HMX (1.91 g cm-3). All energetic compounds show relatively high calculated heat of formation in the range from 504.79 kJ mol-1 to 1405.62 kJ mol-1. Their detonation properties were evaluated by EXPLO5 code using the measured density and calculated heat of formation. Among them, compounds 3 and 4 have good detonation performance (3: D = 8891 m s-1, P = 34.7 GPa, 4: D = 9505 m s-1, P = 41.3 GPa) and acceptable sensitivities (3: IS = 10 J, 4: IS = 4 J), which indicate their potential applications as high-performance energetic materials.

C8 N26 H4 : An Environmentally Friendly Primary Explosive with High Heat of Formation.

The synthesis and characterization of the metal-free polyazido compounds 3,6-bis-(2-(4,6-diazido-1,3,5-triazin-2-yl)-hydrazinyl)-1,2,4,5-tetrazine (2) and 3,6-bis-(2-(4,6-diazido-1,3,5-triazin-2-yl)-diazenyl)-1,2,4,5-tetrazine (4) are presented. Two compounds were characterized by NMR spectra, IR spectroscopy, mass spectrometry, and differential scanning calorimetry (DSC). Additionally, the structure of 2 was confirmed by single-crystal X-ray diffraction. Compounds 2 and 4 exhibit measured densities (1.755 g cm-3 and 1.763 g cm-3 ), good thermal stabilities (194 °C and 189 °C), high heat of formation (2114 kJ mol-1 and 2820 kJ mol-1 ), and excellent detonation performance (D, 8365 m s-1 and 8602 m s-1 ; P, 26.8 GPa and 29.4 GPa). Furthermore, compounds 2 and 4 have been tested for their priming ability to detonate RDX. The results indicate that the title compound 2 is a potential environmentally friendly alternative candidate to lead-based primary explosives.

Incorporating Energetic Moieties into Four Oxadiazole Ring Systems for the Generation of High-Performance Energetic Materials.

The synthesis of three neutral 3,3'-di(1,2,5-oxadiazol-3-yl)-5,5'-bi(1,2,4-oxadiazole) structures in combination with different energetic moieties such as nitramino, trinitroethylamino, and N-nitrated trinitroethylamino is presented. In addition, a novel family of energetic salts based on 4,4'-([5,5'-bi(1,2,4-oxadiazole)]-3,3'-diyl)-bis(1,2,5-oxadiazol-3-nitramide) is synthesized. The new compounds (4, 6-18) are characterized by IR and multinuclear NMR spectroscopy and elemental analysis. The structures of 4⋅2 C4 H8 O2 , 9, 13, 15, and 16 are further confirmed by single-crystal X-ray diffraction studies. The thermal stabilities of 4 and 6-18 are determined by differential scanning calorimetry. Most of the new compounds have high densities (1.72-1.93 g cm-3 ) measured using a gas pycnometer (25 °C). Energetic evaluation indicates that they also have good detonation pressures and velocities (P: 26.4-41.9 GPa; D: 8218-9550 m s-1 ).

Synthesis and Detonation Properties of 5-Amino-2,4,6-trinitro-1,3-dihydroxy-benzene.

5-Amino-4,6-dinitro-1,3-dihydroxy-benzene (6) was synthesized through the ring-opening reaction of macrocyclic compound 4 with the aid of VNS (vicarious nucleophilic substitution of hydrogen) reaction conditions. The mechanism of ring opening of macrocyclic compound 4 was studied. 5-Amino-2,4,6-trinitro-1,3-dihydroxy-benzene (8) was obtained after the nitration of 6 in KNO3 and concentrated sulfuric acid. The thermal stability, sensitivity, and other detonation performances of 6 or 8 were compared to commercially used 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) or 1,3,5-trinitrotriazacyclohexane (RDX), respectively. All target compounds were characterized by using single-crystal X-ray diffraction, NMR spectroscopy, elemental analysis, and differential scanning calorimetry. The sensitivities were determined by using BAM methods (drop-hammer and friction tests). Performance parameters, including heats of formation and detonation properties, were calculated by using Gaussian 03 and EXPLO5 v6.01 programs, respectively. It is worth pointing out that compound 8 has a remarkable measured density of 2.078 g cm-3 at 298 K. In addition, compound 8 is more insensitive than RDX (compound 8: IS=11 J; RDX: IS=7 J; IS is the impact sensitivity).