An eco-efficient synthetic route for the preparation of high-performance carbonate anodes for Li+ and Na+ batteries is developed. With supercritical CO2 (scCO2) as the precursor, which has gas-like diffusivity, extremely low viscosity, and near-zero surface tension, CoCO3 particles are uniformly formed and tightly connected on graphene nanosheets (GNSs). This synthesis can be conducted at 50 °C, which is considerably lower than the temperature required for conventional preparation methods, minimizing energy consumption. The obtained CoCO3 particles (ca. 20 nm in diameter), which have a unique interpenetrating porous structure, can increase the number of electroactive sites, promote electrolyte accessibility, shorten ion diffusion length, and readily accommodate the strain generated upon charging/discharging. With a reversible capacity of 1105 mAh g−1, the proposed CoCO3/GNS anode shows an excellent rate capability, as it can deliver 745 mAh g−1 in 7.5 min. More than 98 % of the initial capacity is retained after 200 cycles. These properties are clearly superior to those of previously reported CoCO3-based electrodes for Li+ storage, indicating the merit of our scCO2-based synthesis, which is facile, green, and can be easily scaled up for mass production.
|Number of pages||9|
|State||Published - 9 Jun 2017|
- energy storage
- green chemistry
- supercritical fluids