No abstract

Bismuth-antimony alloy is considered as a promising potassium ion battery anode because of its combination of the high theoretical capacity of antimony and the excellent rate capacity of bismuth. However, the large volume change and sluggish reaction kinetic upon cycling have triggered severe capacity fading and poor rate performance. Herein, a nanoconfined BiSb in tremellalike carbon microspheres (BiSb@TCS) are delicately designed to address these issues. As-prepared BiSb@TCS renders an outstanding potassiumstorage performance with a reversible capacity of 181 mAh g −1 after ultralong 5700 cycles at a current density of 2 A g −1 , and an excellent rate capacity of 119.3 mAh g −1 at 6 A g −1 . Such a superior performance can be ascribed to the delicate microstructure. The self-assembled carbon microspheres can strengthen integral structure and effectively accommodate the volume expansion of BiSb nanoparticles, and 2D carbon nanowalls in carbon microspheres can provide fast ion/electron diffusion dynamic. Theoretical calculation also suggests a thermodynamic feasibility of alloyed BiSb nanoparticles for storing potassium ion. Such a work shows that BiSb@TCS possesses a great potential to be a high-performance anode of potassium ion batteries. The rational designing of multiscaled structure would be instructive to the exploitation of other energy-storage materials.

Antimony-based materials have been considered as highly competitive anodes for sodium-ion batteries (SIBs) because of their high theoretical capacity. However, the poor rate capability and fast capacity fading originated from...

The influence of transition metals (TMs) on the hydriding/dedydriding critical point of NaAlH 4 has been studied using the chemical potential method. The theoretical results predict that, if the reaction system reaches equilibrium, most of the TM additives significantly increase its hydriding/dedydriding critical point in the sequence Pd > Co > Zr > Ni > Nb > Hf > Ti > Mn > Fe > V > Cu > Cr and therefore have destabilizing effects on NaAlH 4 in the same sequence. Experimentally, the isothermal dehydriding kinetics of NaAlH 4 is studied only with Fe, Ti, and FeTi additives. The experimental results show that the destabilizing effect of Fe and Ti additives with coarse particles is very low while more effective destabilizing ability is achieved with fine FeTi particles. These experimental results suggest that the predicted destabilizing effect of TM additive is hindered kinetically due to the coarse particles of additives, and therefore experimental verification of the destabilizing effect of TMs should be performed with nanosized particles.