Ti Doping Decreases Mn and Ni Dissolution from High-Voltage LiNi_0.5Mn_1.5O₄ Cathodes

LiNi_0.5Mn_1.5O₄ (LNMO), with its high operating voltage, is a favorable cathode material for lithium-ion batteries. However, Ni and Mn dissolution and the associated low cycle life limit their widespread adoption. In this work, we investigate titanium doping as a strategy to mitigate Mn and Ni dissolution from LNMO electrodes. We demonstrate bulk doping of Ti in LNMO up to nominal compositions of x = 0.15 in LiNi_0.5Mn_1.5-x Ti _x O₄. Electrochemical characterization shows that titanium doping enhances the cycle life in LNMO-based half- and full cells with a negligible decrease in capacity or rate capability. Half-cells with LiNi_0.5Mn_1.35Ti_0.15O₄ cathodes and lithium anodes exhibited a capacity retention of 90% after 300 cycles at 1C. Li₄Ti₅O₁₂/LiNi_0.5Mn_1.35Ti_0.15O₄ full cells with Li₄Ti₅O₁₂ anodes cycled at 1C rate to 100% depth of discharge retained ∼73% of the original capacity at the end of 1000 cycles. Our work shows that cathode modification strategies could still be used for enhancing the electrochemical performance of high-voltage cathodes, while using conventional Li-ion battery electrolytes. Improving the cathode stability in conjunction with electrolyte modification could enable the development of practical high-voltage Li-ion batteries.