Electrochemical features of ball-milled lithium manganate spinel for rapid-charge cathodes of lithium ion batteries

摘要

Lithium manganese oxide (LMO), mechano-chemically modified by ball-milling, is a potentially useful active material for high-power-density cathodes of lithium ion batteries. The present work investigates the electrochemical characteristic of a cathode prepared from a controlled mixture of nano- and micrometric LMO particles processed in this approach. The nanoparticles in the mixture support surface-localized insertion/extraction of Li and thus increase the cathode charge/discharge rates. The LMO micro-particles promote cathode cyclability by stabilizing the coexisting nanoparticles against segregation and strong electrolyte reactions. The underlying mechanisms of these effects are studied here using voltammetry, galvanostatic cycling, Ragone plot construction, and electrochemical impedance spectroscopy. The relative timescales of charge transfer and diffusion of Li+ within the LMO lattice are determined, and the criteria for material utilization during rapid charge–discharge are examined.