The design of hydrogen storage materials is one of the principal challenges that must be met before the development of a hydrogen economy. While hydrogen has a large specific energy, its volumetric energy density is so low as to require development of materials that can store and release it when needed. While much of the research on hydrogen storage focuses on metal hydrides, these materials are currently limited by slow kinetics and energy inefficiency. Nanostructured materials with high surface areas are actively being developed as another option. These materials avoid some of the kinetic and thermodynamic drawbacks of metal hydrides and other reactive methods of storing hydrogen. In this work, progress towards hydrogen storage with nanoporous materials in general and porous organic polymers in particular is critically reviewed. Mechanisms of formation for crosslinked polymers, hypercrosslinked polymers, polymers of intrinsic microporosity, and covalent organic frameworks are discussed. Strategies for controlling hydrogen storage capacity and adsorption enthalpy via manipulation of surface area, pore size, and pore volume are discussed in detail.
Thermal runway constitutes the most pressing safety issue in lithium‐ion batteries and supercapacitors of large‐scale and high‐power density due to risks of fire or explosion. However, traditional strategies for averting thermal runaway do not enable the charging–discharging rate to change according to temperature or the original performance to resume when the device is cooled to room temperature. To efficiently control thermal runaway, thermal‐responsive polymers provide a feasible and reversible strategy due to their ability to sense and subsequently act according to a predetermined sequence when triggered by heat. Herein, recent research progress on the use of thermal‐responsive polymers to enhance the thermal safety of electrochemical storage devices is reviewed. First, a brief discussion is provided on the methods of preventing thermal runaway in electrochemical storage devices. Subsequently, a short review is provided on the different types of thermal‐responsive polymers that can efficiently avoid thermal runaway, such as phase change polymers, polymers with sol–gel transitions, and polymers with positive temperature coefficients. The results represent the important development of thermal‐responsive polymers toward the prevention of thermal runaway in next‐generation smart electrochemical storage devices. 相似文献
Solution-processable conducting polymers (CPs) are a compelling alternative to inorganic counterparts because of their potential for tuning chemical properties and creating flexible organic electronics. CPs, which typically comprise either only an electron donor (D) or its alternative combinations with an electron acceptor (A), exhibit charge transfer behavior between the units, resulting in an electrical conductivity suitable for utilization in electronic devices and for energy storage applications. However, the energy storage behavior of CPs with a sequence of electron acceptors (A–A), has rarely been investigated, despite their promising lower band gap and higher charge carrier mobility. Utilizing the aforesaid concept herein, four CPs featuring benzodithiophenedione (BDD), and diketopyrrolepyrrole (DPP) are synthesized. Among them, the BDDTH-DPPEH polymer exhibited the highest specific capacitance of 126.5 F g−1 at a current density of 0.5 A g−1 in an organic electrolyte over a wide potential window of −0.6–1.4 V. Notably, the supercapacitor properties of the polymeric electrode materials improved with increasing conjugation length by adding thiophene donor units and shortening the alkyl chain lengths. Furthermore, a symmetric supercapacitor device fabricated using BDDTH-DPPEH exhibited a high-power density of 4000 W kg−1 and an energy density of 31.66 Wh kg−1. 相似文献
