PNNL

Abstract

The interfacial stability is one of the crucial factors affecting long-term cyclability of lithium (Li) metal batteries (LMBs). While cross contamination (such as Mn+2 crossover from cathode to contaminate graphite anode) phenomena has been well studied in Li ion batteries (LIBs), the similar phenomena has rarely been studied in LMBs. Here, we systematically investigated the cathode failure triggered by the chemical crossover between the electrode pair in rechargeable LMBs. In strong contrast to LIBs, the cathode in LMBs suffers more significant and irreversible capacity fade during cycling and its capacity cannot be fully recovered even when Li metal anode has been replaced in the successive cycling. In-depth characterizations of the cathode surface reveal severe CEI deterioration related to the accumulation of highly resistive polymeric components and lithium fluoride. The soluble decomposition products generated by extensive salt-anion decomposition at Li metal surface can diffuse toward cathode side and result in severe deterioration of cathode as well asseparator surfaces. A polydopamine coated separator with selective Li-ion permeability has been developed to mitigate the detrimental chemical crossover and enhance the cathode stability.