Minsi Li

Amorphous Red Phosphorus Embedded in Highly Ordered Mesoporous Carbon with Superior Lithium and Sodium Storage Capacity

Red phosphorus (P) have been considered as one of the most promising anode material for both lithium-ion batteries (LIBs) and (NIBs), because of its high theoretical capacity. However, natural insulating property and the large volume expansion of red P during cycling lead to poor cyclability and low rate performance, which prevents its practical application. Here, we significantly improves both lithium storage and sodium storage performance of red P by confining nanosized amorphous red P into the mesoporous carbon matrix (P@CMK-3) using a vaporization-condensation-conversion process. The P@CMK-3 shows a high reversible specific capacity of ∼ 2250 mA h g(-1) based on the mass of red P at 0.25 C (∼ 971 mA h g(-1) based on the composite), excellent rate performance of 1598 and 624 mA h g(-1) based on the mass of red P at 6.1 and 12 C, respectively (562 and 228 mA h g(-1) based on the mass of the composite at 6.1 and 12 C, respectively) and significantly enhanced cycle life of 1150 mA h g(-1) based on the mass of red P at 5 C (500 mA h g(-1) based on the mass of the composite) after 1000 cycles for LIBs. For Na ions, it also displays a reversible capacity of 1020 mA h g(-1) based on the mass of red P (370 mA h g(-1) based on the mass of the composite) after 210 cycles at 5C. The significantly improved electrochemical performance could be attributed to the unique structure that combines a variety of advantages: easy access of electrolyte to the open channel structure, short transport path of ions through carbon toward the red P, and high ionic and electronic conductivity.

Confined Amorphous Red Phosphorus in MOF-Derived N-Doped Microporous Carbon as a Superior Anode for Sodium-Ion Battery

Red phosphorus (P) has attracted intense attention as promising anode material for high-energy density sodium-ion batteries (NIBs), owing to its high sodium storage theoretical capacity (2595 mAh g-1 ). Nevertheless, natural insulating property and large volume variation of red P during cycling result in extremely low electrochemical activity, leading to poor electrochemical performance. Herein, the authors demonstrate a rational strategy to improve sodium storage performance of red P by confining nanosized amorphous red P into zeolitic imidazolate framework-8 (ZIF-8) -derived nitrogen-doped microporous carbon matrix (denoted as P@N-MPC). When used as anode for NIBs, the P@N-MPC composite displays a high reversible specific capacity of ≈600 mAh g-1 at 0.15 A g-1 and improved rate capacity (≈450 mAh g-1 at 1 A g-1 after 1000 cycles with an extremely low capacity fading rate of 0.02% per cycle). The superior sodium storage performance of the P@N-MPC is mainly attributed to the novel structure. The N-doped porous carbon with sub-1 nm micropore facilitates the rapid diffusion of organic electrolyte ions and improves the conductivity of the encapsulated red P. Furthermore, the porous carbon matrix can buffer the volume change of red P during repeat sodiation/desodiation process, keeping the structure intact after long cycle life.

Carbon‐Coated Germanium Nanowires on Carbon Nanofibers as Self‐Supported Electrodes for Flexible Lithium‐Ion Batteries

A hybrid structure with carbon-coated germanium nanowires grown on the surface of carbon nanofibers is fabricated using an in situ vapor-liquid-solid process. It is used as a self-supported and flexible anode for Li-ion batteries.

Novel understanding of carbothermal reduction enhancing electronic and ionic conductivity of Li4Ti5O12 anode

Spinel Li4Ti5O12 performance highly depends on both the electronic and ionic conductivity, however, developing a low-cost strategy to improve its electronic and ionic conductivity still remains challenging. In this study, a facile cost-saving carbothermal reduction method is introduced to synthesize the microscaled spinel Li4Ti5O12 particles with the surface modification of Ti(III) using anatase–TiO2, Li2CO3, and acetylene black (AB) as precursors. Remarkably, this ingenious design can easily eliminate the influence of the residual carbon, and thus makes it possible to individually study the effect of the Ti(III) on the bulk Li4Ti5O12. To reveal the role of the Ti(III), the electronic conductivity and lithium-ion diffusion coefficient of the as-prepared materials were measured using a direct volt-ampere method, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results indicate that the carbothermal reduction leads to the increased electronic and ionic conductivity of the spinel Li4Ti5O12. As a result, the modified Li4Ti5O12 exhibits an enhanced cyclic stability, improved rate capability, and high Coulombic efficiency. The carbothermal reduction mechanism discreetly clarified in this study is beneficial to improving Li4Ti5O12 performance for further commercial applications.

Carbon nanofiber-based nanostructures for lithium-ion and sodium-ion batteries

Carbon nanofibers (CNFs) belong to a class of one-dimensional (1D) carbonaceous materials with excellent electronic conductivity, leading to their use as conductive additives in electrode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs). Additionally, CNFs show excellent lithium- and sodium-storage performance when used directly as anode materials via template and activation strategies to produce numerous intercalation sites. In the case of the non-carbon electrodes for LIBs & NIBs, CNFs are capable of functioning as electron conducting and porous substrates to enhance the overall electronic & ionic conductivity and stabilizing the structures of electrodes during cycling, facilitating the improvement of the electrochemical performance of non-carbon anode and cathode materials. In this review, we present a comprehensive summary of the recent progress of CNF application in LIBs and NIBs, focusing on the structural evolution and the resulting improvements in electrochemical performance and demonstrating the importance of advancements in CNF-based electrode materials.

Exsolved Fe–Ni nano-particles from Sr2Fe1.3Ni0.2Mo0.5O6 perovskite oxide as a cathode for solid oxide steam electrolysis cells

A stable and catalytically active cathode consisting of homogeneously dispersed nano-socketed Fe–Ni particles has been elegantly fabricated in single-step treatment for solid oxide steam electrolysis cells via the in situ reduction of the Sr2Fe1.3Ni0.2Mo0.5O6 (SFMNi) material in a humidified H2 (3 vol% H2O) atmosphere at 800 °C. The SFMNi–SDC/LCO/LSGM/SDC–LSCF electrolysis cell exhibits a high electrolysis current density of 1257 mA cm−2 and a high hydrogen production rate of 525 mL cm−2 h−1 at an applied voltage of 1.3 V at 850 °C. Moreover, the in situ grown nano-structured cathode shows a good short-term stability at a constant electrolysis current of −300 mA cm−2, resulting from the strong interface between the exsolved particles and the parent perovskite.

Sudden energy release at the vicinity of a vortex

An investigation on vortex-explosion interaction was carried out experimentally and numerically. The experiment was conducted in a shock tube, in which a vortex is generated when a shock wave propagates around a wing-shaped model, and an explosion is triggered at the time when the vortex arrives to the position where the exploding wire is located. Holographic interferometry was used to visualize interaction flow field. In the numerical simulation, a series of different conditions in which the explosion is triggered at various positions related to the center of the vortex were considered. Both experimental and numerical results showed that the vortex, after disturbed by the explosion, can be strongly deformed or smeared out, which implies that vortex might be suppressed or even destroyed by the interaction of the explosion, especially when the explosion is started at the center of the vortex.