High-capacity materials such as Si and C-Si composites are popular candidates for next generation anodes. However, these materials consume significant amounts of lithium during the formation of Solid Electrolyte Interface (SEI), leading to a large irreversible loss of lithium for cycling and loss of overall cell capacity. One approach to offsetting this effect is to overload the cathode to provide additional lithium. However, this approach reduces the overall cell energy density and reduces the benefits of using a higher capacity anode material. To enable better full cell implementation of Si based anodes, an additional source of sacrificial lithium for SEI formation would be desirable if it could be added to the cell without a significant weight penalty.

We have demonstrated the use of the dual cast technique to incorporate additional Li into the battery cell system using existing slurry casting procedures. The dual cast of NMC and Li2O2 has shown an increase in first cycle capacity up to 2.2x the capacity of traditional NMC cathodes under the same cycling conditions. Characteristic voltage profile curves were confirmed to be present only when Li2O2 was included in the cell. To achieve the full benefit of the additional lithium the voltage maximum must be increased to 4.6V during the initial break-in cycles. The capacity increase due to the Li2O2 was beyond the increase due to the overcharging that can occur when NMC is cycled beyond 4.3V to 4.6V. It was also shown that the dual cast electrodes with Li2O2 could tolerate being cycled in the presence of a carbonate solvent base electrolyte.