Dehydration Rather Than HF Capture Explains Performance Improvements of Li-Ion Cells by Ceramic Nanoparticles

Instability of nickel-rich layered oxides at high voltages is an impediment to their wider use in Li-ion batteries. HF generated via LiPF6 hydrolysis accelerates corrosion, further destabilizing the material. Ceramic particles are believed to interfere with this corrosion by scavenging HF. Here we show that the likely mechanism is, in fact, disruption of the hydrolytic cycle due to adsorption of water on ceramic particles, which MgO performed the best. We suggest that hydrolysis prevention rather than post-factum remediation of hydrolytic damage makes a more efficient strategy for protection of the high-voltage cathodes.