Conformal Surface Coatings to Enable High Volume Expansion Li‐Ion Anode Materials

Abstract

An alumina surface coating is demonstrated to improve electrochemical performance of MoO(3) nanoparticles as high capacity/high-volume expansion anodes for Li-ion batteries. Thin, conformal surface coatings were grown using atomic layer deposition (ALD) that relies on self-limiting surface reactions. ALD coatings were tested on both individual nanoparticles and prefabricated electrodes containing conductive additive and binder. The coated and non-coated materials were characterized using transmission electron microscopy, energy-dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, and galvanostatic charge/discharge cycling. Importantly, increased stability and capacity retention was only observed when the fully fabricated electrode was coated. The alumina layer both improves the adhesion of the entire electrode, during volume expansion/contraction and protects the nanoparticle surfaces. Coating the entire electrode also allows for an important carbothermal reduction process that occurs during electrode pre-heat treatment. ALD is thus demonstrated as a novel and necessary method that may be employed to coat the tortuous network of a battery electrode.

Surface chemistry of LiNi0.5Mn1.5O4 particles coated by Al2O3 using atomic layer deposition for lithium-ion batteries

“…8,11 However, the fact that the high energy density of LNMO, enabled by the high operating voltage, is offset by limitations in the thermodynamic-stability window of conventional organic liquid electrolytes remains a critical issue. [9,11] Mn dissolution is also a serious problem, not only in and anode materials including graphite, [7,22,25] silicon, [29] and metal oxides [30,31] have been demonstrated to significantly improve the performance and safety of the cells.…”

Growth of crystalline Al2O3 via thermal atomic layer deposition: Nanomaterial phase stabilization

“…Since some of the uses for ALD Al 2 O 3 films include gate oxide for electronics, 3,4 protective barriers, 5 as well as potential coatings in energy materials, [6][7][8][9][10] it is critical to characterize these coatings on the nanoscale. For example, in the case of energy materials, there are recent reports of enhanced stability and extended cycling of Li-ion battery nanomaterials coated with ALD Al 2 O 3 thin films, [6][7][8][9][10] 9 This work assumes that the Al 2 O 3 coating is amorphous, as would be expected. However, it has also been noted that since the Al 2 O 3 coating should be insulating, there is an issue with the Li atom and electron diffusion, which should degrade the performance, in contradiction of the reported results.…”

Recent Development of Advanced Electrode Materials by Atomic Layer Deposition for Electrochemical Energy Storage

“…ALD surface coating helps improve on conversional and intercalation metal oxides, such as Fe 2 O 3 , MoO 3 and Li 4 Ti 5 O 12 47, 48, 49. As has been reported by Lipson et al, a relatively thick and rough SEI is formed on the surface of the uncoated MnO anode, while ALD Al 2 O 3 coated MnO (with a thickness of 3 Å) can effectively prevent the formation of such SEI and maintain the capacity for more than 100 cycles 50.…”