Polyvinylidenefluoride based Janus separators for lithium batteries

The next step towards the development of new-generation the lithium-ion batteries (LIBs) is to replace the traditional graphite anode with lithium metal to improve the energy density of the battery [1]. The problem of using lithium metal is the generation of dendrite, conductive filaments of lithium, which eventually penetrate the separator and short the cell causing thermal runaway and degradation [2]. In the last few years, functionalized “Janus” separators for LIBs able to mitigate dendrite formation and growth have been proposed [3]. In this work we report on a nano-composite Janus separator made by an insulating side, in contact with the anode, based on PVDF-HFP and Al2O3 and a semiconducting side including multi-walled nanotubes (CNT’s). The ionic conductivity at room temperature of the separator exceeds 2.4*10-3S cm-1. The blocking effect of the separator vs. lithium dendrites has been investigated by galvanostatic cycling on symmetric Li/Janus/Li cells with the help of post-mortem SEM analysis (Figure 1.).