Enhancing low electronic conductivity materials in all active material electrodes through multicomponent architecture

Abstract

Lithium-ion batteries are used in many applications due to their high volumetric and gravimetric energy density. One general route to increase cell level battery energy density is to use thick electrodes, although as electrode thickness increases electronic and ionic microstructure transport limitations must be given more consideration. One system that enables the development and study of very thick electrodes is “All Active Material” (AAM) electrodes, which are comprised of only electroactive material which has been mechanically compressed and mildly thermally treated to result in a porous electrode pellet. In this manuscript, the incorporation of a material with relatively high gravimetric capacity but low electronic conductivity into an AAM cathode will be described. The material, LiNi_0.5Mn_0.5O₂ (LNMO), when used in isolation has very high polarization as an AAM electrode which is attributed to the low electronic conductivity in the electrode microstructure. A second material with higher electronic conductivity but lower gravimetric capacity, LiCoO₂ (LCO), was combined with the LNMO to form a multicomponent AAM cathode. The LCO/LNMO blends displayed improvements in electrochemical battery properties attributed to the LCO forming a percolated network for electron conduction while the LCO and LNMO particles/phases still remained segregated in the electrode architecture. The electrochemical outcomes were further analyzed in the context of pseudo-two-dimensional simulations of cycling the cells. This study establishes a new concept in incorporating relatively low electronic conductivity materials into AAM electrodes by taking advantage of a multicomponent architecture.