Graphite particles modified by ZnO atomic layer deposition for Li-ion battery anodes†

Abstract

Graphite, with a modest specific capacity of 372 mA h 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 an irregular solid electrolyte interphase (SEI) can result in unstable performance. In this research, we used a few cycles of atomic layer deposition (ALD) to deposit 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 characterization demonstrated that the ZnO ALD nanoparticles significantly inhibited dendrite growth, and X-ray photoelectron spectroscopy 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% higher discharge capacity 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 composites for high-performance batteries.