Organic molecules have been considered promising energy‐storage materials in aqueous zinc‐ion batteries (ZIBs), but are plagued by poor conductivity and structural instability because of the short‐range conjugated structure and low molecular weight. Herein, an imine‐based tris(aza)pentacene (TAP) with extended conjugated effects along the CN backbones is proposed, which is in situ injected into layered MXene to form a TAP/Ti3C2Tx cathode. Theoretical and electrochemical analyses reveal a selective H+/Zn2+ co‐insertion/extraction mechanism in TAP, which is ascribed to the steric effect on the availability of active CN sites. Moreover, Ti3C2Tx, as a conductive scaffold, favors fast Zn2+ diffusion to boost the electrode kinetics of TAP. Close electronic interactions between TAP and Ti3C2Tx preserve the structural integrity of TAP/Ti3C2Tx during the repeated charge/discharge. Accordingly, the TAP/Ti3C2Tx cathode delivers a high reversible capacity of 303 mAh g−1 at 0.04 A g−1 in aqueous ZIBs, which also realizes an ultralong lifetime over 10 000 cycles with a capacity retention of 81.6%. Furthermore, flexible Zn||TAP/Ti3C2Tx batteries with a quasi‐solid‐state electrolyte demonstrate potential application in wearable electronic devices. This work offers pivotal guidance to create highly stable organic electrodes for advanced ZIBs.
We study the interference patterns of a superfluid Fermi gas released from optical lattices below and above Feshbach resonance based on a simple phenomenological approach. We first solve the order-parameter equation valid for the crossover from Bardeen-Cooper-Schrieffer ͑BCS͒ superfluid to a Bose-Einstein condensate ͑BEC͒ to obtain an initial distribution of subcondensates formed in an optical lattice. Then we investigate the coherent evolution of the subcondensates when both harmonic oscillator and optical lattice potentials are switched off. The interference patterns of the superfluid Fermi gas along the BCS-BEC crossover during a nearly ballistic expansion are calculated by means of Feynman propagator method combined with numerical simulations. The result obtained agrees with the recent experimental observation reported by the MIT group ͓J. K. Chin et al., Nature ͑London͒ 443, 961 ͑2006͔͒.
We investigate the dynamical behavior of large-amplitude collective modes in a superfluid Fermi gas in the crossover from Bardeen-Cooper-Schrieffer ͑BCS͒ superfluid to Bose-Einstein condensate ͑BEC͒ based on a hydrodynamic approach. We first solve the superfluid hydrodynamic equations that describe the time evolution of fermionic condensates in the BCS-BEC crossover and calculate explicitly the frequency shifts of the collective modes induced by nonlinear effects using the Lindstedt-Poincaré method. The result shows that the frequency shifts display different features in different superfluid regimes. We then study the second-harmonic generation of the collective modes under a phase-matching condition, which can be fulfilled by choosing appropriate parameters of the system. The analytical results obtained are checked by numerical simulations and good agreement is found.
The Landau damping and frequency-shift of monopole mode in an elongated-rubidium Bose-Einstein condensate are investigated by using the time-dependent Hartree-Fock-Bogoliubov approximation. Improving the previous approach, We have taken into account the practical relaxations of elementary excitations and the orthogonal relation among them. With such an approach, we provide a new calculation formula for Landau damping rate and frequency-shift. In addition, our previous method of eliminating the divergence in three-mode coupling matrix elements is also improved by zeroing the kinetic energy at the condensate boundary instead of minimizing the ground-state energy. Based on these improvements, both the Landau damping rate and the frequency-shift of the monopole mode are analytically calculated and their temperature dependences are also discussed. And all the theoretical results are in agree meat with experimental data.
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