Direct regeneration of LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode material from spent lithium-ion batteries

At present,metal ions from spent lithium-ion batteries are mostly recovered by the acid leaching procedure,which unavoidably introduces potential pollutants to the environment.Therefore,it is necessary to develop more direct and effective green recycling methods.In this research,a method for the direct regeneration of anode materials is reported,which includes the particles size reduction of recovered raw materials by jet milling and ball milling,followed by calcination at high temperature after lithium supplementation.The regenerated LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) single-crystal cathode material possessed a relatively ideal layered structure and a complete surface morphology when the lithium content was n(Ni+Co+Mn):n(Li)=1:1.10 at a sintering temperature of 920 0 C,and a sintering time of 12 h.The first discharge specific capacity was 154.87 mA·h·g^(-1) between 2.75 V and 4.2 V,with a capacity retention rate of 90% after 100 cycles.

Effects of long-term fast charging on a layered cathode for lithium-ion batteries

Fast charging, which aims to shorten recharge times to 10–15 min, is crucial for electric vehicles(EVs),but battery capacity usually decays rapidly if batteries are charged under such severe conditions.Revealing the failure mechanism is a prerequisite to improving the charging performance of lithium(Li)-ion batteries. Previous studies have focused less on cathode materials while also mostly focusing on their early changes. Thus, the cumulative effect of long-term fast charging on cathode materials has not been fully studied. Here, we study the changes in a layered cathode material during 1000 cycles of 6 C charging based on 1.6 Ah LiCoO_(2)/graphite pouch cells. Postmortem analysis reveals that the surface structure, charge transfer resistance and Li-ion diffusion coefficient of the cathode degenerate during repeated fast charging, causing a large increase in polarization. This polarization-induced poor utilization of the Li inventory is an important reason for the rapid capacity fading of batteries. These findings deepen the understanding of the aging mechanism for cells undergoing fast charging and can be used as benchmarks for the future development of high-capacity, fast-charging layered cathode materials.

An aqueous ZnCl2/Fe(bpy)3Cl2 flow battery with mild electrolyte

The kinetics of electrode reaction was investigated by cyclic voltammetry,and cyclic voltammograms show that the reversibility of the Fe(bpy)3^2+/Fe(bpy)^3+electrode reaction is better than that of the Zn/Zn^2+electrode reaction on the graphite disc.However,the Fe(bpy)3^2+ion diffusion in electrolyte is subject to greater resistance than that of the Zn^2+ion one.The stability of the Fe(bpy)3Cl2 solution was investigated by UV-vis spectroscopy,and the performance of a mild redox flow battery employing ZnCl2 and Fe(bpy)3Cl2 in the NaCl aqueous solution with various membranes as the separator was also investigated.It was found that the Celgard 3501 membrane cannot effectively prevent Fe(bpy)3^2+ions from leaking into anolyte,leading to the rapid failure of the flow battery.Although the Nafion 115 membrane can be polluted by Fe(bpy)32+ions,it is not invalidated.The Nafion 115 membrane shows good selectivity,which can avoid Fe(bpy)32 ions from leakage into anolyte.The ZnCl2/Fe(bpy)3Cl2 flow battery with the Nafion 115 membrane exhibits the capacity retention of 80%after 200 cycles.