The inhomogeneous Li electrodeposition of lithium metal electrode has been a major impediment to the realization of rechargeable lithium metal batteries. Although single ion conducting ionomers can induce more homogeneous Li electrodeposition by preventing Li+ depletion at Li surface, currently available materials do not allow room-temperature operation due to their low room temperature conductivities. In the paper, we report that a highly conductive ionomer/liquid electrolyte hybrid layer tightly laminated on Li metal electrode can realize stable Li electrodeposition at high current densities up to 10 mA cm−2 and permit room-temperature operation of corresponding Li metal batteries with low polarizations. The hybrid layer is fabricated by laminating few micron-thick Nafion layer on Li metal electrode followed by soaking 1 M LiPF6 EC/DEC (1/1) electrolyte. The Li/Li symmetric cell with the hybrid layer stably operates at a high current density of 10 mA cm−2 for more than 2000 h, which corresponds to more than five-fold enhancement compared with bare Li metal electrode. Also, the prototype Li/LiCoO2 battery with the hybrid layer offers cycling stability more than 350 cycles. These results demonstrate that the hybrid strategy successfully combines the advantages of bi-ionic liquid electrolyte (fast Li+ transport) and single ionic ionomer (prevention of Li+ depletion).
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机译:锂金属电极的不均匀Li电沉积已成为实现可充电锂金属电池的主要障碍。尽管单个离子导电离聚物可以通过防止Li表面的Li + sup>耗尽来诱导更均匀的Li电沉积,但是由于其低的室温电导率,目前可用的材料不允许在室温下运行。在本文中,我们报道了紧密层压在锂金属电极上的高导电性离聚物/液体电解质混合层可以在高达10 mA cm -2 sup>的高电流密度下实现稳定的锂电沉积,并允许室温相应的低极化锂金属电池的运行。通过在锂金属电极上层压几微米厚的Nafion层,然后浸入1 M LiPF6 EC / DEC(1/1)电解质来制造混合层。具有混合层的Li / Li对称电池在10 mA cm −2 sup>的高电流密度下稳定工作超过2000 h,与裸露的Li金属相比,增强了五倍以上电极。同样,具有混合层的原型Li / LiCoO2电池具有超过350次循环的循环稳定性。这些结果表明,该混合策略成功地结合了双离子液体电解质(快速的Li + sup>传输)和单离子离聚物(防止Li + sup>耗尽)的优势。
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