Low-sensitivity and high-energy explosives (LSHEs) are highly desired for their comprehensive superiority of safety and energy. Crystal packing is crucial to both the safety and energy, and therefore becomes of interest in energetic crystal engineering. This work carries out systemic analyses on the crystal packing of 11 existing LSHEs with both energy and safety close or superior to TNT. As a result, we find that the LSHE crystals wholly feature π−π stacking with the aid of intermolecular hydrogen bonding. Each LSHE molecule is πbonded with a big conjugated structure composed of all nonhydrogen atoms in the entire molecule. Intramolecular hydrogen bonding exists in most LSHE molecules with strongly active hydrogen bond (HB) donors of amino and hydroxyl groups, and various strength. These big π-conjugated structures and intramolecular HBs lead to planar molecules with high stability, settling a base of π−π stacking in crystals. With the help of intermolecular HBs, the π−π stacking holding the LSHE crystals appears in four modes. Among them, the face-to-face stacking (always offset) gives rationally the smallest steric hindrance when interlayer slide occurs in crystal, which is the reason for very low impact sensitivity. This work suggests that the planar conjugated molecular structure and intermolecular hydrogen bonding supporting the π−π stacking are necessary to the crystal engineering of LSHEs.

Molecular and crystal designs are crucial to the engineering of high-energy explosives, which are a class of substantial materials usually with high costs and high risks.Understanding their structures, properties, and performances, and the relationships among them is the basis for the design. As a continuation of a systemic analysis of the crystal packing of low-sensitivity and high-energy explosives (LSHEs) (Cryst. Growth Des. 2014, 14, 4703−4713), we present in this work another analysis of 10 existing impact-sensitive high-energy explosives (SHEs), which possess both velocities of detonation and impact sensitivity close to or higher than those of RDX. We find that SHE molecules are usually less stable than LSHE ones, due to the deficiencies of big π-conjugated molecular structures, and adequate and strong intramolecular hydrogen bonds (HBs) even though H atoms are contained. The intermolecular HBs cannot be formed sometimes in H-contained SHE crystals, and the noncovalent O•••O interactions dominate the connection of SHE molecules to build a three-dimensional network and hold crystals, generally, with the strength above intermolecular HBs. The absence of single-atom-layered stacking in SHE crystals makes the intermolecular sliding difficult or even unallowed when against impact, which leads to inefficiency of energy buffering and ease of molecular decay, hot spot formation, and final combustion or detonation. In contrast to LSHEs, SHEs are disadvantageous on dual structural levels causing their high sensitivity: molecules with low stability and crystals without HB-aided single-atom-layered stacking. It re-verifies that the intermolecular HB-aided π−π stacking is necessary for crystal engineering of LSHEs, which are highly desired currently.

is the most powerful explosive applied, and CL-20-based energetic-energetic co-crystals are promising new alternative explosives with tunable power and safety, resulting in much interest in them. This work discusses the structural, electronic and energetic features of three CL-20 polymorphs, β, γ and ε forms, and three CL-20-based energeticenergetic co-crystals, CL-20/TNT, CL-20/HMX and CL-20/BTF. As a result, we find that, relative to the pure CL-20 polymorphs, the co-crystallization of CL-20 with HMX, TNT and BTF cause little molecular deformation except from some torsion of its nitro groups, and the narrower band gaps. And dominantly, the O⋯O, O⋯H and O⋯N interactions hold all the crystal packing. There is possibly thermodynamic and kinetic dominance in the CL-20/TNT and CL-20/HMX, and CL-20/BTF co-crystallization, respectively, in terms of their formation energy. Further, a rough criterion for predicting energetic co-crystal formation is obtained, as the solubility parameter difference of two coformers of a binary energetic co-crystal is less than 8 MPa 0.5 .

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SSEs based on sulfides, [2] oxides, [3] halides, [4] and borohydrides [5] have been developed over the past decades, including those demonstrating high ionic conductivity (e.g., 12 mS cm −1 for Li 10 GeP 2 S 12 , LGPS, and 25 mS cm −1 for Li 9.54 Si 1.74 P 1.44 S 11.7 Cl l0.3 , LSPSCl), [2] highvoltage stability (e.g., 4.21 V versus Li + / Li for Li 3 YCl 6 , LYC, and 4.3 V versus Li + / Li for Li 3 InCl 6 , LIC), [6] low cost (Li 2 ZrCl 6 and Li 2.25 Zr 0.75 Fe 0.25 Cl 6 ), [7] and appropriate mechanical properties. [8] With these advances in SSEs, various cathode materials have been attempted in ASSBs, such as LiCoO 2 (LCO), [9] LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532), [10] and Ni-rich layered cathode materials (e.g., LiNi 0.8 Mn 0.1 Co 0.1 O 2 , NMC811, [4c] LiNi 0.85 Co 0.1 Mn 0.05 O 2 ,Ni85, [11] and LiNi 0.90 Co 0.05 Mn 0.05 O 2 , Ni90 [12] ). These cathode materials typically show a specific capacity of <200 mAh g −1 , [13] which limits the energy density of ASSBs to less than 450 Wh kg −1 . [14] Comparatively, lithium-rich layered oxide (LLO) possesses a higher theoretical capacity of ≥250 mAh g −1 , [15] and is thus a promising candidate for achieving ASSBs with an energy density of 500 Wh kg −1 Employing lithium-rich layered oxide (LLO) as the cathode of all-solid-state batteries (ASSBs) is highly desired for realizing high energy density. However, the poor kinetics of LLO, caused by its low electronic conductivity and significant oxygen-redox-induced structural degradation, has impeded its application in ASSBs. Here, the charge transfer kinetics of LLO is enhanced by constructing high-efficiency electron transport networks within solidstate electrodes, which considerably minimizes electron transfer resistance. In addition, an infusion-plus-coating strategy is introduced to stabilize the lattice oxygen of LLO, successfully suppressing the interfacial oxidation of solid electrolyte (Li 3 InCl 6 ) and structural degradation of LLO. As a result, LLO-based ASSBs exhibit a high discharge capacity of 230.7 mAh g −1 at 0.1 C and ultra-long cycle stability over 400 cycles. This work provides an in-depth understanding of the kinetics of LLO in solid-state electrodes, and affords a practically feasible strategy to obtain high-energy-density ASSBs.