Double Nitrogenation Layer Formed Using Nitric Oxide for Enhancing Li⁺ Storage Performance, Cycling Stability, and...

To enhance Li storage properties, nitrogenation methods are developed for Si anodes. First, melamine, urea, and nitric oxide (NO) precursors are used to nitrogenize carbon-coated Si particles. The properties of the obtained particles are compared. It is found that the NO process can maximize the graphitic nitrogen (N) content and electronic conductivity of a sample. In addition, optimized N functional groups and O─C species on the electrode surface increase electrolyte wettability. However, with a carbon barrier layer, NO hardly nitrogenizes the Si cores. Therefore, bare Si particles are reacted with NO. Core-shell Si@amorphous SiN_x particles are produced using a facile and scalable NO treatment route. The effects of the NO reaction time on the physicochemical properties and charge-discharge performance of the obtained materials are systematically examined. Finally, the Si@SiN_x particles are coated with N-doped carbon. Superior capacities of 2435 and 1280 mAh g^-1 are achieved at 0.2 and 5 A g^-1, respectively. After 300 cycles, 90% of the initial capacity is retained. In addition, differential scanning calorimetry data indicate that the multiple nitrogenation layers formed by NO significantly suppress electrode exothermic reactions during thermal runaway.