Lithium sulfide (Li₂S) is considered as a promising lithium storage material because of its high theoretical specific capacity of 1166 mA h g⁻¹.

Hierarchical porous carbon (HPC) has attracted much attention in tackling global environmental and energy problems. For the state-of-the-art routes to synthesize HPC from organic compounds, the emission of carbon dioxide (CO₂) and gaseous pollutants is inevitable during thermal carbonization. Herein, we report an environmentally benign and high-yield route to synthesize HPC from CO₂via H₂O-induced self-propagating reactions. By introducing an initiator of H₂O, CO₂ can react with lithium hydride (LiH) to produce HPC in 13 seconds at low temperatures. The as-synthesized HPC exhibits an interconnected micro–meso–macropore network structure with a high porosity of 83%. The formation mechanism of HPC is discussed on the basis of the conversion reactions from CO₂ to C and the gas blowing effect in producing hierarchical porosity. The HPC evaluated as an anode material for lithium-ion batteries not only delivers a high reversible capacity of ∼1150 mA h g⁻¹ at a current density of 0.2 A g⁻¹, but also exhibits superior rate capability (∼825 mA h g⁻¹ at 1.0 A g⁻¹) and excellent cycling properties (up to 2000 cycles). This research opens a new avenue both to synthesize HPC from CO₂ on a large scale and to mitigate greenhouse gas from the atmosphere.

Hierarchical porous carbon (HPC) has become increasingly important in tackling global environmental and energy-related challenges. However, its wide utilization is still limited by the complicated and environment-unfriendly synthesis process. Herein, we report a green and facile strategy to synthesize HPC from abundant metal carbonates without any emission of CO₂ or/and noxious gases. The sponge-like HPC synthesized from reacting lithium carbonate (Li₂CO₃) with lithium hydride (LiH) exhibits high specific surface area and porosity, enabling high-performance lithium storage. The Li₂CO₃-derived HPC achieves a reversible capacity of ∼1750 mA h g⁻¹ at a current density of 0.2 A g⁻¹, among the highest reversible lithium storage capacities for HPCs. Moreover, excellent cycling stability and superior rate performance are demonstrated with a high capacity of 505 mA h g⁻¹ even at 4.0 A g⁻¹ over 2000 stable cycles. Such a rational and environment-friendly strategy might pave the way for the large-scale synthesis and utilization of HPCs in high-performance energy storage.