New insight into Li/Ni disorder in layered cathode materials for lithium ion batteries: a joint study of neutron diffraction, electrochemical kinetic analysis and first-principles calculations

Abstract

Although layered cathode materials LiNi_xMn_yCo_1−x−yO₂ have attracted much attention due to their number of advantages, the issue of Li/Ni disorder seriously restricts their electrochemical properties. It is very important and pivotal for the better optimization of layered cathode materials to clearly explain the detailed relationships among the Li/Ni disorder, Li⁺ migration resistance, electrochemical kinetics and electrochemical properties. Here we focus on the LiNi_xMn_yCo_1−x−yO₂ cathode material and report relationships among the crystal structures, Li⁺ migration resistance, electrochemical kinetics and electrochemical properties by combining neutron diffraction techniques, electrochemical kinetic analysis techniques and first-principles calculation methods. The results suggest that more Li⁺/Ni²⁺ ion exchange will shrink the inter-slab space thickness, causing a higher Li⁺ ion migration barrier and inferior electrochemical kinetics, all of which should be responsible for the limited electrochemical properties.