Design,synthesis And Electrochemical Performance Of Micro-Nano Structure For Lithium Metal Anode

At present,the secondary batteries,mainly lithium-ion batteries,become a core part of electronic devices,electric vehicles,due to their good price/performance ratio.However,with the pursuit of better performance in the fields of electronic products and electric vehicles,extensive researches on the technology of the post-lithium-ion battery with high energy density（lithium-sulfur battery and lithium-air battery with lithium metal as anode）are.carried out.Uncontrolled dendrite growth and severe volume fluctuations hinder their practical application.The uneven distribution of lithium-ion flow caused by uneven current collectors is exacerbated especially in the case of high current density,and the problem of lithium dendrites is aggravated,which is easy to pierce the separator and cause irreversible effects.Introducing a framework can effectively reduce the local current density and the unevenness of the lithium ion flow on the electrode surface,which is one of the effective strategies to prevent lithium dendrites from piercing separator at high rates.Therefore,two three-dimensional frameworks are developed,and the following experiments are mainly carried out:1.A type of porous CoP framework which was converted to metallic Co and Li3P during the first discharge was developed.The product after converting featured the mixed ionic and electronic conductivity,serving as a host material for dendrite free lithium deposition under high current.The metallic Co with good conductivity could form Co-Li alloy which reduced the nucleation energy barrier of lithium,and the Li3P with high ion conductivity could ensure uniform lithium-ion distribution.Furthermore,the vertically-aligned porous CoP structure provided more active area and relieved the volume fluctuations,leading to uniform lithium nucleation and growth.An average CE of 98.63%was achieved for 1000 h lithium plating/striping.The symmetrical cell could achieve an overpotential of 20 mV for over 350 h under 1 mA cm^-2 and 1 mAh cm^-2.2.In order to further improve the cycle life of battery,a high surface area and lithium-rich mixed conductor of 3D porous Sn-Li alloy was designed.The alloy was transformed from 3D porous Sn made by a facile electrodeposition process.The scaffold not only reduced the lithium nucleation barrier but also ensured a uniform lithium-ion distribution.Furthermore,the lithium-rich Sn-Li alloy stored a certain amount of lithium which could be reversibly stripped to compensate for the loss of irreversible lithium to further improved the cycle life.The Li ‖ Cu cell with the framework could cycled for 200 h at 5 mA cm^-2 and the symmetrical cell could run for more than 700 h with a stable overpotential of 24 mV.