A proof-of-concept graphite anode with a lithium dendrite suppressing polymer coating

Abstract

Dendritic Li deposition on graphite anodes of Li-ion batteries (LIBs) not only deteriorates the anode performance but also causes safety concerns. We demonstrate here a proof-of-concept graphite anode containing a polymer coating that effectively mitigates Li dendrite formation under harsh lithiation conditions. It is shown that Li dendrites with dimensions ranging from a few tens nanometers to microns occur readily on granular graphite electrodes either under 20% over-lithiation at 0.2C or fast lithiation up to 10C rate. In contrast, the graphite anode with a conformal thin coating of high-polarity £]-phase polyvinylidene difluoride (PVDF) on graphite particles exhibits dendrite-free Li plating under either condition. Moreover, the PVDF coated graphite anode exhibits substantially improved cycling stability with high Coulombic efficiencies under the Li-plating conditions. The rise of charge-transfer resistance due to over-lithiation is reduced. The proof of concept for adopting a dendrite-suppressing polymer coating on graphite anodes offers a new strategy for improving battery safety and renders more options for cell design in enhancing energy and power performances for the state-of-the-art LIBs. ? 2018 Elsevier B.V.