英语论文翻译演讲稿(空心碳纳米管用两亲性物质表面改性)（小编推荐）

第一篇：英语论文翻译演讲稿(空心碳纳米管用两亲性物质表面改性)（小编推荐）

Hello, erverbody!Today I’d like to talk something about Lithium Sulfur Batteries, based on a thesis named “Amphiphilic Surface Modification of Hollow Carbon Nanofibers for Improved Cycle Life of Lithium Sulfur Batteries”.Then, I’ll talk in the light of the four points—overview of thesis，rate capability，cycling performance and voltage profiles of Lithium Sulfur Batteries after Modification.Ok, first, introduce something about Lithium Sulfur Batteries.The advantage of Lithium sulfur batteries is their high specific energy and relatively low cost.However, the major problems of sulfur cathode include low active material utilization, poor cycling performance and low Coulombic efficiency.Think about the question: What caused the loss of electrical contact and capacity decay in Lithium sulfur bactaries? Dissolution of lithium polysulfides has long been understood to be the major problem of sulfur cathode.But now, the experimental results suggest that loss of polysulfides into the electrolyte may not be the sole reason contributing to capacity decay,sulfur

cathode degradation is a multifaceted problem.At the same time, they consider that sulfur cathode degradation requires rational design at different length scales:

(1)Proper functional groups,its chemical moieties need to have good binding strength

(2)The contact surface area between sulfur and the electrolyte should be minimal

(3)Sulfur should be evenly distributed in the electrode

Following the guiding principles mentioned just now, they investigated the effect of adding amphiphilic polymers in modifying the interface between sulfur and the hollow carbon nanofiber.They decided to chose polyvinylpyrrolidone(PVP)due to its simple molecular structure and availability.And then, talk about the electrochemical performance of sulfur cathode after surface modification.First, its rate capability.Figure（a）shows the rate capability performance of the modified sulfur cathode.AtC/5, a specific capacity of around 1180 mAh/g was achieved.The specific capacities were

around 920 mAh/g and 820 mAh/g atC/2 and 1C, respectively.Then, its cycling performance.Figure(b)shows the comparison of cycling performance at C/2 with and without the PVP modification.The red line represents modified electrode and black line represents unmodified electrode.Instead of the rapid initial decay generally observed in the unmodified electrodes, the first few cycles of modified electrodes showed a slight increase in specific capacity from 828 to 838 mAh/g.The amphiphilic polymers provide anchoring points that allow lithium sulfides to bind strongly with the carbon surface.Subsequent cycles showed very stable performance,with less than 3% decay over the first 100 cycles.The capacity retention was over 80% for more than 300 cycles of charge/discharge, with Coulombic efficiency at around 99%.Now, talk about its voltage profiles.Figure(c)shows the voltage profiles of the first, 10th, 50th and 200th cycles at C/2.The first discharge shows a small initial plateau, probably due to the reaction between sulfur and the electrolytes.The voltage profiles from

the 10th cycle onward are quite similar to each other.The hysteresis between the charge and discharge cycles also decreases significantly during cycling, which could be due to the mitigation of electrode resistance during cycling.In summary, Interfacial modification of carbon with amphiphilic polymers helps stabilize the discharge products and improve the cycling performance.We demonstrated that the modified sulfur cathode could achieve stable performance of more than 300 cycles with 80% capacity retention.Thank you!