Aqueous sodium-ion batteries (AIBs) are promising candidates for large-scale energy storage due to their safe operational properties and low cost. However, AIBs have low specific energy (i.e., <80 Wh kg−1) and limited lifespans (e.g., hundreds of cycles). Mn-Fe Prussian blue analogues are considered ideal positive electrode materials for AIBs, but they show rapid capacity decay due to Jahn-Teller distortions. To circumvent these issues, here, we propose a cation-trapping method that involves the introduction of sodium ferrocyanide (Na4Fe(CN)6) as a supporting salt in a highly concentrated NaClO4-based aqueous electrolyte solution to fill the surface Mn vacancies formed in Fe-substituted Prussian blue Na1.58Fe0.07Mn0.97Fe(CN)6 · 2.65H2O (NaFeMnF) positive electrode materials during cycling. When the engineered aqueous electrolyte solution and the NaFeMnF-based positive electrode are tested in combination with a 3, 4, 9, 10-perylenetetracarboxylic diimide-based negative electrode in a coin cell configuration, a specific energy of 94 Wh kg–1 at 0.5 A g−1 (specific energy based on the active material mass of both electrodes) and a specific discharge capacity retention of 73.4% after 15000 cycles at 2 A g−1 are achieved.
We report a silicate-clad heavily Tm3+-doped germanate core multimaterial fiber that is successfully drawn by using a rod-in-tube method. This new fiber has a high gain per unit length of 6.11 dB/cm at 1.95 µm, which is, to the best of the authors’ knowledge, the highest gain per unit length reported so far for Tm3+-doped glass fibers. By virtue of this high-gain glass fiber, an all-fiber-integrated passively mode-locked fiber laser with a fundamental repetition rate up to 4.3 GHz is demonstrated. Remarkably, the generated pulse operating at 1968 nm exhibits a signal-to-noise ratio of >76 dB in the radio-frequency domain. These results suggest that the silicate-clad heavily Tm3+-doped germanate core multimaterial fiber can act as a key building block for high repetition rate mode-locked fiber lasers at 2 µm.
In this work, we report on the vector and scalar soliton dynamics that result from inevitable fiber birefringence in an 8-mm Er3+/Yb3+ fiber based Fabry-Férot (FP) laser that has a free spectral range of up to 12.5 GHz. The generation of polarization-evolving vector solitons can largely degrade the performance of application systems, and the underlying mechanisms and manipulation technologies are yet to be explored. To realize the transition from vector to scalar (linearly polarized) state, we here incorporate the polarization selection effect (PSE) in the simulation model and the numerical results verify that only a small amount of PSE is sufficient for manipulating the soliton dynamics. It also reveals that, prominent polarization-dependent intensity discrimination can be acquired via geometry-induced oblique incidence to the Bragg mirror of the semiconductor saturable absorber mirror (SESAM), and we obtain switchable operating states by tilting the SESAM in the experiments. These efforts create a feasible method to manipulate high-repetition-rate pulse and may shed light on understanding the dissipative soliton dynamics in ultrafast fiber FP lasers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.