Uniform Li deposition regulated via three-dimensional polyvinyl alcohol nanofiber networks for effective Li metal anodes
Uniform Li deposition regulated via three-dimensional polyvinyl alcohol nanofiber networks for effective Li metal anodes
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通过三维聚乙烯醇纳米纤维网络调节均匀的锂沉积，形成有效的锂金属阳极
DOI：
10.1039/c8nr01995a
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发表时间：
2018
期刊：
影响因子：
6.7
通讯作者：
Liu Meilin
中科院分区：
文献类型：
--
作者：
Wang Gang;Xiong Xunhui;Lin Zhihua;Zheng Jie;Zheng Fenghua;Li Youpeng;Liu Yanzhen;Yang Chenghao;Tang Yiwei;Liu Meilin
锂金属负极因其高的可逆容量和极低的负极电位被认为是下一代先进储能器件最有前途的负极材料。然而，由于固体电解质界面层的反复断裂和修复而形成的枝晶锂，往往导致循环性能差、库仑效率低，以及严重的安全问题，长期阻碍了锂阳极的实际应用。在这里，我们设计了一种电极，通过电纺技术在聚乙烯醇层上覆盖三维纳米纤维网络结构。聚合物纳米纤维表面的极性官能团可以限制Li沿纤维的沉积，并均匀地调节Li在纳米纤维之间的空隙中的沉积。由于聚合物的结构特点，修饰后的锂铜电极具有良好的循环稳定性，在电流密度为1 mA cm−2、沉积容量为1 mA h cm−2的条件下，循环200次后库仑效率高达98.6%；而使用聚合物修饰锂电极的对称电池在电流密度为5 mA cm∼2的情况下，在600 h内循环稳定，滞后电压为80 mV，循环时间为600 h。
Lithium metal anodes are considered to be the most promising anode material for next-generation advanced energy storage devices due to their high reversible capacity and extremely low anode potential. Nevertheless, the formation of dendritic Li, induced by the repeated breaking and repairing of solid electrolyte interphase layers, always causes poor cycling performance and low coulombic efficiency, as well as serious safety problems, which have hindered the practical application of Li anodes for a long time. Herein, we design an electrode by covering a polyvinyl alcohol layer with a three-dimensional nanofiber network structure through an electrospinning technique. The polar functional groups on the surface of the polymer nanofibers can restrict the deposition of Li along the fibers and regulate the deposition of Li uniformly in the voids between the nanofibers. Owing to the structural features of the polymer, the modified Li|Cu electrode displays excellent cycle stability, with a high coulombic efficiency of 98.6% after 200 cycles at a current density of 1 mA cm−2 under a deposition capacity of 1 mA h cm−2, whilst the symmetric cell using the polymer modified Li anode shows stable cycling with a low hysteresis voltage of ∼80 mV over 600 h at a current density of 5 mA cm−2.