A universal charge-compensating strategy for high-energy-density pseudocapacitors

For pseudocapacitive electrode materials(PseEMs),despite much progress having been made in achieving both high power density and high energy density,a general strategy to guide the enhancement of intrinsic capacitive properties of PseEMs remains lacking.Here,we demonstrate a universal chargecompensating strategy to improve the charge-storage capability of PseEMs intrinsically:ⅰ) in the electrolyte with anion as charge carriers(such as OH-),reducing the multivalent cations of PseEMs into lower valences could create more reversible low-to-high valence redox cou ples to promote the intercalation of the anions;ⅱ) in the electrolytes with cation as charge carriers(such as H^(+),Li^(+),Na^(+)),oxidizing the multivalent cations of PseEMs into higher valences could introduce more reversible high-to-low valence redox couples to promote the intercalation of the cations.And we demonstrated that the improved intrinsic charge-storage capability for PseEMs originates from the increased Faradaic charge storage sites.

A Universal Strategy For N-Doped 2D Carbon Nanosheets With Sub-Nanometer Micropore For High-Performance Supercapacitor

Preparing carbon nanosheets with precise control of open porous morphology via universal process and understanding the relationship between structure and capacitive performance are very urgent for achieving advanced supercapacitors.Herein,we propose a simple yet effective additive-free method to transform a bulk layered potassium phthalimide salt to novel nitrogen-doped twodimensional carbon sheets by self-activation during calcination.The obtained samples showed large-sized and flat structure with lateral size around 10μm,uniform sub-nanometer micropore size distribution of about 0.65 nm dimension,large specific surface area up to 2276.7 m^(2)g^(-1),and suitable nitrogen doping.Benefited from these merits,the optimized sample delivers a high specific capacitance of 345 F g^(-1)at 1 A g^(-1)and retains 270 F g^(-1)even at 50 A g^(-1)in6.0 M KOH electrolyte.Remarkably,the symmetric supercapacitor shows maximum energy densities of 16.43 Wh kg^(-1)and 23.6 Wh kg^(-1)in 6.0 M KOH and 1.0 M Na_(2)SO_(4)electrolytes,respectively.Importantly,on account the universality and simplicity of this method,the undoped as-prepared carbon sheet with uniform sub-nanometer micropore distribution can be synthesized from different potassium-containing salts with layered structure,which can be employed as a model for a deep understanding the effect of sub-nanometer micropores on capacitive performances.We find the number of micropores centered at 0.65 nm can be applied as one indicator to clarify the correlation between capacitance and critical pore size below 1 nm.

English Vocabulary Memorizing Strategies by Chinese University Students

The findings of the study indicate that students prefer to engage in the vocabulary learning strategies that would be most appealing to them and that would entail less manipulation of the language. Of the four vocabulary memorizing strategies cited in the study （rote repetition, structural associations, semantic strategies, and mnemonic keyword techniques）, students apparently tended to favor the second and the third ones, though rote repetition remains appealing to some of them. Mnemonic devices such as keyword method were rather unpopular to most of the students because they would involve the learners in more active performance of the target language.

A universal strategy for the refined frameworks and improved performance of distinct commercial polyacrylonitriles in sulfur cathodes

Sulfurized polyacrylonitrile(SPAN)with the exceptional stability,safety,low cost,and high capacity have been positioned as a highly promising cathode material for next-generation lithium-ion batteries.However,in the market,polyacrylonitrile(PAN)sourced from different suppliers and available at varying prices exhibits significant variations in physical and chemical properties,resulting in diverse behaviors in Li-SPAN batteries.By studying the mechanism,we found that the PAN copolymerization structure leads to the stacking of chain segments which obstructs the embedding of sulfur and lithium ions.Here,we propose a universal strategy for the refined frameworks by an exogenous additive to modify various PAN raw materials,and the battery capacity and cycling performance are obviously improved.As a result,the copolymerized SPAN with a poor original capacity is nearly doubled to over 500 mAh g^(-1),almost comparable to high-quality yet expensively imported products;for the sample with a high initial capacity but fading in ether-based electrolytes,it can be modified to maintain stability over 400 cycles.This strategy offers an alternative approach for SPAN modification that is characterized by its simplicity and low cost,thereby facilitating the large-scale development of Li-SPAN batteries.

A universal strategy for achieving dual cross-linked networks to obtain ultralong polymeric room temperature phosphorescence

Efficient polymeric room-temperature phosphorescence(PRTP)with excellent processability and flexibility is highly desirable but still faces formidable challenge.Herein,a general strategy is developed for efficient PRTP through photo-polymerization of phosphor monomers and N-isopropylacrylamide(NIPAM)spontaneously without a crosslinker.Remarkably ultralong lifetime of 3.54 s with afterglow duration time of 25 s and decent phosphorescent quantum efficiency of 13%are achieved.This efficient PRTP has been demonstrated to be derived from the synergistic effect of the covalent and hydrogen bonds networks formed through photo-polymerization of NIPAM.The electron paramagnetic resonance(EPR)spectra confirmed that methyl radicals are generated under the irradiation of ultraviolet light and promote the formation of covalent cross-linking networks.This strategy has also been proved to be generalizable to several other phosphor monomers.Interestingly,the polymer films display ultrahigh temperature resistance with long afterglows even at 140℃ and unexampled ultralong lifetime of 2.45 s in aqueous solutions.This work provides a simple and feasible avenue to obtain efficient PRTP.