Carbon-coating-increased working voltage and energy density towards an advanced Na3V2(PO4)2F3@C cathode in sodium-ion batteries  

碳包覆提升的工作电压与能量密度:Na3V2(PO4)2F3@C钠离子电池正极材料

作　　者：Zhen-Yi Gu Jin-Zhi Guo Zhong-Hui Sun Xin-Xin Zhao Wen-Hao Li Xu Yang Hao-Jie Liang Chen-De Zhao Xing-Long Wu 谷振一;郭晋芝;孙中辉;赵欣欣;李文灏;杨旭;梁皓杰;赵宸德;吴兴隆(Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education,Northeast Normal University,Changchun 130024,China;National&Local United Engineering Laboratory for Power Batteries,and Department of Chemistry,Northeast Normal University,Changchun 130024,China;Center for Advanced Analytical Science,School of Chemistry and Chemical Engineering,Guangzhou University,Guangzhou 510006,China)

机构地区：[1]Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education,Northeast Normal University,Changchun 130024,China [2]National&Local United Engineering Laboratory for Power Batteries,and Department of Chemistry,Northeast Normal University,Changchun 130024,China [3]Center for Advanced Analytical Science,School of Chemistry and Chemical Engineering,Guangzhou University,Guangzhou 510006,China

出　　处：《Science Bulletin》2020年第9期702-710,M0003,共10页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(91963118);the Fundamental Research Funds for the Central Universities(2412019ZD010).

摘　　要：One main challenge for phosphate cathodes in sodium-ion batteries(SIBs)is to increase the working voltage and energy density to promote its practicability.Herein,an advanced Na3V2(PO4)2F3@C cathode is prepared successfully for sodium-ion full cells.It is revealed that,carbon coating can not only enhance the electronic conductivity and electrode kinetics of Na3V2(PO4)2F3@C and inhibit the growth of particles(i.e.,shorten the Na^+-migration path),but also unexpectedly for the first time adjust the dis-/charging plateaux at different voltage ranges to increase the mean voltage(from 3.59 to 3.71 V)and energy density from 336.0 to 428.5 Wh kg^-1 of phosphate cathode material.As a result,when used as cathode for SIBs,the prepared Na3V2(PO4)2F3@C delivers much improved electrochemical properties in terms of larger specifc capacity(115.9 vs.93.5 mAh g^-1),more outstanding high-rate capability(e.g.,87.3 vs.60.5 mAh g^-1 at 10 C),higher energy density,and better cycling performance,compared to pristine Na3V2(PO4)2F3.Reasons for the enhanced electrochemical properties include ionicity enhancement of lattice induced by carbon coating,improved electrode kinetics and electronic conductivity,and high stability of lattice,which is elucidated clearly through the contrastive characterization and electrochemical studies.Moreover,excellent energy-storage performance in sodium-ion full cells further demonstrate the extremely high possibility of Na3V2(PO4)2F3@C cathode for practical applications.钠离子电池用磷酸盐正极材料面临的主要挑战是如何提升其工作电压和能量密度,以促进其实用性.本文成功制备了一种碳包覆的磷酸盐钠离子电池正极材料(Na3V2(PO4)2F3@C,NVPF@C).研究发现,该碳包覆过程不但可以抑制Na3V2(PO4)2F3(NVPF)颗粒的生长,提升电子电导率和电极动力学性能,而且能够调整不同电压范围内的平台容量,从而将其平均工作电压从3.59 V提升到3.71 V,能量密度从336.0 Wh kg^-1提升到428.5 Wh kg^-1,涨幅27.5%.与未进行碳包覆的NVPF材料相比,NVPF@C表现出明显更加优异的电化学性能,包括更高的放电比容量(NVPF@C为115.9 m Ah g^-1,而NVPF为93.5 m Ah g^-1)、更优的高倍率性能(10 C充放电时,二者的容量分别为87.3和60.5 mAh g^-1)、更高的能量密度和更长的循环寿命.碳包覆诱导的晶格离子性增强、碳包覆调控的晶体生长和脱嵌钠稳定化以及电极动力学和电导率的提升,使NVPF@C表现出更优性能.

关 键 词：Sodium-ion batteries CATHODE Working voltage Na3V2(PO4)2F3 In-situ XRD 

分 类 号：TM912[电气工程—电力电子与电力传动]