well drilling. [1][2][3] Nowadays, dielectric materials with excellent high-temperature capacitive properties are in great demand because of the heat inevitably generated by compact high-power electronic systems. [4][5][6][7] For example, the operating temperature of capacitors is 140-150 °C in green-energy vehicle inverters and reaches 200 °C in electrified aircraft. Biaxially oriented polypropylene (BOPP), the mainstream commercial polymer dielectrics, has discharged energy densities (U e ) <4.0 J cm −3 and a maximum operating temperature below 105 °C. [5,8,9] Therefore, developing dielectric polymers with high working temperatures and large energy storage densities is of critical importance.The current high glass-transitiontemperature (T g ) dielectric polymers, including polyimide (PI), polyetherimide (PEI), polyetheretherketone (PEEK), and fluorene polyester (FPE), usually exhibit low breakdown strength (E b ) and poor capacitive performance at >150 °C because of an exponential increase in conduction loss with the applied field and temperature. [5,10,11] There are two types of conduction mechanisms in dielectrics, i.e., electrode-limited and bulk-limited conduction mechanisms. [6,[12][13][14][15][16][17] Unlike the electrode-limited conduction mechanism that depends on the electrode-dielectric interface, the bulk-limited conduction mechanism is determined by the electrical characteristics High-temperature polymer dielectrics have broad application prospects in next-generation microelectronics and electrical power systems. However, the capacitive energy densities of dielectric polymers at elevated temperatures are severely limited by carrier excitation and transport. Herein, a molecular engineering strategy is presented to regulate the bulk-limited conduction in the polymer by bonding amino polyhedral oligomeric silsesquioxane (NH 2 -POSS) with the chain ends of polyimide (PI). Experimental studies and density functional theory (DFT) calculations demonstrate that the terminal group NH 2 -POSS with a wide-bandgap of E g ≈ 6.6 eV increases the band energy levels of the PI and induces the formation of local deep traps in the hybrid films, which significantly restrains carrier transport. At 200 °C, the hybrid film exhibits concurrently an ultrahigh discharged energy density of 3.45 J cm −3 and a high gravimetric energy density of 2.74 J g −1 , with the charge-discharge efficiency >90%, far exceeding those achieved in the dielectric polymers and nearly all other polymer nanocomposites. Moreover, the NH 2 -POSS terminated PI film exhibits excellent charge-discharge cyclability (>50000) and power density (0.39 MW cm −3 ) at 200 °C, making it a promising candidate for high-temperature high-energy-density capacitors. This work represents a novel strategy to scalable polymer dielectrics with superior capacitive performance operating in harsh environments.

Electrolyte additives have been extensively used as an economical approach to improve Li-ion battery (LIB) performances; however, their selection has been conducted on an Edisonian trial-and-error basis, with little knowledge about the relationship between their molecular structure and reactivity as well as the electrochemical performance. In this work, a series of phosphate additives with systematic structural variation were introduced with the purpose of revealing the significance of additive structure in building a robust interphase and electrochemical property in LIBs. By comparing the interphases formed by tripropyl phosphate (TPPC1), triallyl phosphate (TPPC2), and tripropargyl phosphate (TPPC3) containing alkane, alkene, and alkyne functionalities, respectively, theoretical calculations and comprehensive characterizations reveal that TPPC3 and TPPC2 exhibit more reactivity than TPPC1, and both can preferentially decompose both reductively and oxidatively, forming dense and protective interphases on both the cathode and anode, but they lead to different long-term cycling behaviors at 55 °C. We herein correlate the electrochemical performance of the high energy Li-ion cells to the molecular structure of these additives, and it is found that the effectiveness of TPPC1, TPPC2, and TPPC3 in preventing gas generation, suppressing interfacial resistance growth, and improving cycling stability can be described as TPPC3 > TPPC2 > TPPC1, i.e., the most unsaturated additive TPPC3 is the most effective additive among them. The established correlation between structure–reactivity and interphase-performance will doubtlessly construct the principle foundation for the rational design of new electrolyte components for future battery chemistry.

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Manganites (R1−xAxMnO3, R = rare-earth cation and A = alkali or alkaline earth cation) host an immense number of phases and electronic properties, which can be mainly manipulated through conventional structural control such as metallic cations, oxygen concentration, or misfit strain. However, their practical applications are heavily hindered due to the requirement of rigid synthesis conditions and prolonged treatment time. Herein, a subtle hydrogenation of canonical epitaxial La0.3Sr0.7MnO3 films gives rise to a series of structural transformations ranging from the perovskite to the intermediate state and to the brownmillerite one, accompanied by tunable electronic performances from the antiferromagnetic insulating phase to the weak magnetic insulating one. Moreover, the hydrogenated La0.3Sr0.7MnO3−δ films show an ultra-high magnetic temperature (&gt;400 K). The efficient modulations of the crystalline structure and functionalities of manganite oxides using the facile hydrogenation process enable practical applications of high-temperature magnetic insulators in spintronic devices.

Minimum energy path (MEP) search is a vital but often very time-consuming method to predict the transition states of versatile dynamic processes in chemistry, physics, and materials science. In this study, we reveal that the chemical bond lengths in the MEP structures, including those directly involved in the dynamical processes, largely resemble those in the stable initial and final states. Based on this discovery, we propose an adaptive semi-rigid body approximation (ASRBA) to construct a physically reasonable initial guess for the MEP structures, which can be further optimized by the nudged elastic band method. Examination of several distinct dynamical processes in bulk, on crystal surface, and through two-dimensional system show that the transition state calculations based on the ASRBA results are robust and significantly faster than those based on the popular linear interpolation and image-dependent pair potential methods.