Carbon-coated high nickel cathode nanosheet with stable structure for lithium-ion batteries

High nickel content is favor for improving the capacity of Li-ion batteries, but it would allow the electrode suffering moisture and CO2 corrosion. Thus, high conduction of carbon coating is needed for the electrode. Reduce atmosphere is not favor to prepare LiNi0.92Co0.06Al0.02O2. Therefore, it is a challenge to synthesis carbon coated LiNi0.92Co0.06Al0.02O2. Here, we prepared carbon-coated LiNi0.92Co0.06Al0.02O2 nanosheets by sol-gel-assisted high-temperature annealing. The atomic-level mixing (in the sol-gel process) and volatilization of large amounts of organics (in the annealing process) resulted in a nanosheet structure. Due to the high content of organics, after long time high-temperature annealing, a 2 nm thickness carbon layer is founded on the surface of LiNi0.92Co0.06Al0.02O2. The in situ formed carbon coating layer can protect the electrode from moisture and CO2 corrosion, making it convenient for storage. Furthermore, due to the limited thickness (20 nm) of the nanosheet, the expanded volume could be released in a timely manner and exhibited outstanding structural integrity. Even after 100 cycles, no crack was observed for the cycled electrode. The corresponding discharge capacity after 100 cycles is 181 mAh g(-1) (at 0.5 C), with 90% capacity remaining.