Sophisticated strategies for designing fast-charging lithium-ion batteries without sacrificing the energy density

Abstract

The use of electric vehicles (EVs) is a green approach to mitigating climate change and pollution associated with the emissions of internal combustion engines. Therefore, research on lithium-ion batteries (LIBs), which are major EV components, has become vital. LIBs in EVs should be characterised by high energy and power densities for long-term use. In this study, the electrochemical performance during fast charging was examined with the active material (AM) content kept constant at 94 wt% so as not to sacrifice energy density, and the ratio of conducting agent (CA) to binder altered to account for the remaining 6 wt% of the composition. We evaluated the charging properties of Ni-rich cathodes and carried out cyclic voltammetry, electrochemical impedance spectroscopy, cross-sectional field-emission scanning electron microscopy and pore size distribution analyses. Evidence reveals that when the CA:binder ratio is 4:6, AM is hampered by the binder, which inhibits electronic conduction and hence increases its resistance to electrochemical reactions. On the other hand, at 7:3 CA:binder ratio, the void spaces in the cathode are filled by CA, decreasing porosity and hindering Li+ transfer through the electrolyte. As a result, a 6:4 CA:binder ratio is optimal for fast-charging in terms of electronic and ionic conduction. The results of this study indicate that electrochemical performance can be controlled by the inactive components' ratio, and our research proposes the best electrode composition with respect to the CA:binder ratio for fast-charging.