Electrolyte-Enabled High-Voltage Operation of a Low-Nickel, Low-Cobalt Layered Oxide Cathode for High Energy Density...

The lithium-ion battery industry acknowledges the need to reduce expensive metals, such as cobalt and nickel, due to supply chain challenges. However, doing so can drastically reduce the overall battery energy density, attenuating the driving range for electric vehicles. Cycling to higher voltages can increase the capacity and energy density but will consequently exacerbate cell degradation due to the instability at high voltages. Herein, an advanced localized high-concentration electrolyte (LHCE) is utilized to enable long-term cycling of a low-Ni, low-Co layered oxide cathode LiNi_0.60Mn_0.31Co_0.07Al_0.02O₂ (NMCA) in full cells with graphite or graphite-silicon anodes at 4.5 V (≈4.6 vs Li⁺/Li). NMCA cells with the LHCE deliver a high initial capacity of 194 mA h g^-1 at C/10 rate along with 73% capacity retention after 400 cycles compared to 49% retention in a baseline carbonate electrolyte. This is facilitated by reduced impedance growth, active material loss, and gas evolution with the NMCA cathode. These improvements are attributed to the formation of robust, inorganic-rich interphase layers on both the cathode and anode throughout cycling, which are induced by a favorable salt decomposition in the LHCE. This study demonstrates the efficacy of electrolytes toward facilitating the operation of high-energy-density, long-life, and cost-effective cathodes.