Solid-state lithium battery cathodes operating at low pressures

Many studies of solid-state battery cathodes employ high stack pressures and low current densities. In practice, cells operating at current densities in the mA cm⁻² range at stack pressures of a few MPa are required. Here, we show the influence of the composite cathode components LiNi_0.83Mn_0.06Co_0.11O₂, Li₃InC_l6, and carbon nanofibers, operating at 2-MPa stack pressure and find that the overall composite cathode capacity is determined primarily by the conductivity of the solid electrolyte. Higher conductivities reduce the mass of the solid electrolyte required to access a high capacity from the active material (high utilization), enabling higher active material loadings and higher overall capacities. Cycling between 2.6 and 4.2 V rather than 4.4 V reduces the LiNi_0.83Mn_0.06Co_0.11O₂ volume change from 6% to 2.5%, achieving 94% rather than 65% capacity retention after 50 cycles for a reduction in capacity of only 14%.