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A new type hybrid energetic material through the integration of energetic molecule HMX and polymeric carbon nitrides is reported. The hybrid complex shows high thermal stability and low impact sensitivity, which provides security guarantee in practical application. Further, the import of hydrazone-linked polymeric carbon nitrides blocks the phase transition of HMX from high energetic β -phase to low energetic δ -phase. This work provides a new strategy for the construction of new hybrid energetic materials with high thermostability and low sensitivity. [Display omitted] • Hybrid complex was prepared via combination of energetic molecule HMX and polymeric carbon nitrides. • Polymeric carbon nitrides MHGP realized the morphology constraint of high-energy crystal β -HMX. • The mechanism of morphology constraint was thoroughly investigated. The exploration of hybrid energetic materials is of great importance because of their enhanced performances and promising applications in aerospace exploration, military and civil technologies. Herein, a new type hybrid energetic material is prepared by the integration of energetic molecule HMX and polymeric carbon nitrides (PCNs). Two PCNs-HMX were prepared from melem and melem hydrazine by in-situ self-assembly on HMX with glyoxal, the complexes were named as MGP-HMX and MHGP-HMX, respectively. The planar structure and conjugated π-system of 2D-PCNs benefit the reduced sensitivities and help to control the polymorphism of HMX. The hybrid complexes MGP-HMX and MHGP-HMX demonstrate remarkably high thermal stabilities. An interesting morphology constraint effect of β -HMX is observed only for the hydrazone-linked MHGP, but not for the imine-linked MGP. The constraint effect blocks the solid–solid transition of HMX from high energetic β -phase to low energetic δ -phase. The key to constrain the solid–solid morphology transition in MHGP-HMX is furtherly investigated by visualization of the interaction in composite materials. The massive hydrogen bonds between NO 2 groups of HMX and hydrazone moieties of MHGP and the squeezing of HMX in 2D layers account for the morphology constrain. The morphology constraint via PCNs provides a new strategy for the construction of new hybrid energetic materials with high thermostability and low sensitivity. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) are recognized as promising energy storage devices. However, they suffer from rapid capacity decay at ultra‐low temperatures due to high Na+ desolvation energy barrier and unstable solid electrolyte interphase (SEI). Herein, a weakly solvating electrolyte (WSE) with decreased ion‐dipole interactions is designed for stable sodium storage in hard carbon (HC) anode at ultra‐low temperatures. 2‐methyltetrahydrofuran with low solvating power is incorporated into tetrahydrofuran to regulate the interactions between Na+ and solvents. The reduced Na+‐dipole interactions facilitate more anionic coordination in the first solvation sheath, which consistently maintains anion‐enhanced solvation structures from room to low temperatures to promote inorganic‐rich SEI formation. These enable WSE with a low freezing point of −83.3 °C and faster Na+ desolvation kinetics. The HC anode thus affords reversible capacities of 243.2 and 205.4 mAh g−1 at 50 mA g−1 at −40 and −60 °C, respectively, and the full cell of HC||Na3V2(PO4)3 yields an extended lifespan over 250 cycles with high capacity retention of ~100 % at −40 °C. This work sheds new lights on the ion‐dipole regulation for ultra‐low temperature SIBs. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) are recognized as promising energy storage devices. However, they suffer from rapid capacity decay at ultra‐low temperatures due to high Na+ desolvation energy barrier and unstable solid electrolyte interphase (SEI). Herein, a weakly solvating electrolyte (WSE) with decreased ion‐dipole interactions is designed for stable sodium storage in hard carbon (HC) anode at ultra‐low temperatures. 2‐methyltetrahydrofuran with low solvating power is incorporated into tetrahydrofuran to regulate the interactions between Na+ and solvents. The reduced Na+‐dipole interactions facilitate more anionic coordination in the first solvation sheath, which consistently maintains anion‐enhanced solvation structures from room to low temperatures to promote inorganic‐rich SEI formation. These enable WSE with a low freezing point of −83.3 °C and faster Na+ desolvation kinetics. The HC anode thus affords reversible capacities of 243.2 and 205.4 mAh g−1 at 50 mA g−1 at −40 and −60 °C, respectively, and the full cell of HC||Na3V2(PO4)3 yields an extended lifespan over 250 cycles with high capacity retention of ~100 % at −40 °C. This work sheds new lights on the ion‐dipole regulation for ultra‐low temperature SIBs. [ABSTRACT FROM AUTHOR]