Interphase Control in Lithium Metal Batteries Through Electrolyte Design
<p>Future rechargeable Li metal batteries (LMBs) require a rational electrolyte design to stabilize</p><p>the interfaces between the electrolyte and both the lithium metal anode and the high voltage</p><p>cathode. This remains the greatest challenge in achieving high cycling performance in</p><p>LMBs. We report an ether-aided ionic liquid electrolyte which offers superior Li metal</p><p>deposition, high voltage (5 V) stability and non-flammability. High performance cycling of</p><p>LiNi0.8Mn0.1Co0.1O2 (4.4 V) and LiNi0.6Mn0.2Co0.2O2 (4.3 V) cells is demonstrated with high</p><p>coulombic efficiency (>99.5%) at room temperature and elevated temperatures, even at high</p><p>practical areal capacity for the latter of 3.8 mAh/cm2 and with a capacity retention of 91% after</p><p>100 cycles. The ether-ionic liquid chemistry enables desirable plated Li microstructures with</p><p>high packing density, minimal ‘dead’ or inactive lithium formation and dendrite-free long-term</p><p>cycling. Along with XPS studies of cycled electrode surfaces, we use molecular dynamics</p><p>simulations to demonstrate that changes to the electrolyte interfacial chemistry upon addition</p><p>of DME plays a decisive role in the formation of a compact stable SEI.</p>