Improving high-temperature performance of lithium-rich cathode by roll-to-roll atomic layer deposition of titania nanocoating for lithium-ion batteries

Lithium-rich layered oxides are attractive cathode materials for next-generation lithium-ion batteries thanks to their ultra-high specific capacities commonly surpassing 200 mAh g − 1. However, poor cycling stability and sluggish reaction kinetics inhibit their widespread applications. To alleviate this critical drawback, in this work, we have developed a unique roll-to-roll atomic layer deposition (R2R ALD) apparatus to continuously coat TiO2 nanolayers on the Li-rich cathode sheets. To confirm the efficacy of the design, the TiO2-coated Li-rich cathodes were electrochemically cycled within an aggressive voltage range (2.0–4.8 V) at 25 and 60 °C for 200 cycles. The rate capability, cyclic stability, and electrode polarization were significantly improved for high-temperature operation via coating a finely tuned TiO2 nanolayer on the layered cathodes. The TiO2 nanolayer effectively alleviates the metal migration and cation mixing within the Li-rich layered structure during high-temperature cycling. The R2R ALD technique engineered in this study enables continuous coating of TiO2 nanolayers on the Li-rich electrodes with ultra-high production rates (> 1.2 m min−1).