Significant Capacity and Cycle‐Life Improvement of Lithium‐Ion Batteries through Ultrathin Conductive Film Stabilized Cathode Particles

Atomic layer deposition (ALD), as a thin film deposition technique, has been explored as a viable path to improve the performance of lithium‐ion batteries. However, a trade‐off between the species transport (capacity) and protection (lifetime), resulting from the insulating properties of ALD films, is the key challenge in ALD technology. Here we report a breakthrough to overcome this trade‐off by coating an ultrathin conformal cerium dioxide (CeO 2 ) film on the surfaces of LiMn 2 O 4 particles. The optimized CeO 2 film (≈3 nm) coated particles exhibit a significant improvement in capacity and cycling performance compared to uncoated (UC), Al 2 O 3 coated, and ZrO 2 coated samples at room temperature and 55 °C for long cycling numbers. The initial capacity of the 3 nm CeO 2 ‐coated sample shows 24% increment compared to the capacity of the uncoated one, and 96% and 95% of the initial capacity is retained after 1000 cycles with 1C rate at room temperature and 55 °C, respectively. The detailed electrochemical data reveal that the suppression of the impedance rise and the facile transport of the species are the main contributors to the success.