Graphite Particles Modified by ZnO Atomic Layer Deposition for Li-ion Battery Anode

Abstract

Graphite, with a modest specific capacity of 372 mAh g-1, is a stable material for lithium-ion battery anodes. However, its capacity is inadequate to meet the growing power demands because the formation of irregular solid electrolyte interphase (SEI) can result in unstable performance. In this research, we used atomic layer deposition (ALD) to deposit a few cycles of ZnO on graphite particles as an anode with improved electrochemical stability. Transmission electron microscopy revealed that ZnO was in the form of nanoparticles due to the inert surface properties of graphite and only a few cycles of ALD. Electrochemical characterizations demonstrated that the ZnO ALD nanoparticles significantly inhibited dendrite growth, and X-ray photoelectron spectroscopy (XPS) revealed that side reactions at the electrolyte-electrode interface were inhibited with the deposition of ZnO. The SEI layer was stabilized, which improved the cycling stability of the ZnO-graphite composite electrode. The electrode made of graphite with 2 cycles of ZnO ALD had about 20% discharge capacity higher than that of pristine graphite, and it remained stable at 420 mA h g-1 after 500 cycles of charge/discharge. This surface modification technique can significantly increase the potential use of widely available graphite composite for high-performance batteries.