Eco‐Efficient Synthesis of Highly Porous CoCO₃ Anodes from Supercritical CO₂ for Li⁺ and Na⁺ Storage

Abstract

An eco-efficient synthetic route for the preparation of high-performance carbonate anodes for Li and Na batteries is developed. With supercritical CO (scCO ) as the precursor, which has gas-like diffusivity, extremely low viscosity, and near-zero surface tension, CoCO 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 CoCO 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 , the proposed CoCO /GNS anode shows an excellent rate capability, as it can deliver 745 mAh g 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 CoCO -based electrodes for Li storage, indicating the merit of our scCO -based synthesis, which is facile, green, and can be easily scaled up for mass production.

Supercritical CO2‐Assisted SiOx/Carbon Multi‐Layer Coating on Si Anode for Lithium‐Ion Batteries

“…In addition, our team has demonstrated that SCCO 2 itself can serve as the precursor in the synthesis of a highly porous CoCO 3 /graphene nanocomposite anode for Li + and Na + storage. [ 36 ] The charge–discharge properties were superior to those of the conventionally synthesized CoCO 3 counterpart. To the best of our knowledge, using SCCO 2 to create coating layers on Si particles has not been previously attempted.…”

Preparation of Small-Particle and High-Density Cobalt Carbonate Using a Continuous Carbonate Precipitation Method and Evaluation of Its Growth Mechanism

“…Compared to the hydrothermal process and solvothermal process, the solubility product, namely K sp , of carbonate or bicarbonate precipitation processes is 1.4 × 10 −13 , presenting a relatively high precipitation efficiency. Furthermore, the precipitation process is widely industrialized in the precursor field for manufacturing the used 3C lithium ion battery to prepare the cobalt oxide, aluminum-doped cobalt oxide, and lithium cobalt oxide due to the fact that the raw materials are cheap and easy to obtain, while the preparation technology is simple and the production efficiency is high [20,21,22,23].…”

Supercritical Fluid‐Facilitated Exfoliation and Processing of 2D Materials

“…As an anode material for LIBs, graphene exhibits a theoretical specific capacity of 744 mAh g −1 , provided that lithium is bound on both sides of graphene to form Li 2 C 6 . RGO (initial discharge capacities of 540–1600 mAh g −1 at 50 mA g −1 ), modified RGO, and RGO‐based composite materials (such as graphene/Si, graphene/CoCO 3 , and graphene/LiFePO 4 ) may be promising alternatives for high‐performance LIBs. For example, hydrogen‐enriched rGO derived by reduction of double‐oxidized GO in scIPA exhibited a rather high reversible discharge capacity of 1331 mAh g −1 even after 100 cycles at a current rate of 50 mA g −1 , which outperformed thermally reduced GO and scIPA reduced single‐oxidized GO electrodes .…”