Interconnected highly graphitic carbon nanosheets (HGCNS) have been successfully synthesized via a combined hydrothermal and graphitization process that uses biomass waste (wheat stalk) as the precursor. The as-obtained HGCNS show favorable features for electrochemical energy storage such as high degree of graphitization (up to 90.2%), ultrathin nanosheet frameworks (2–10 atomic layers), graphite-like interlayer spacing (0.3362 nm), and a mesoporous structure. Due to these unique features of HGCNS, they not only can supply multiple sites for the storage and insertion of Li ions, but also can facilitate rapid mass transport of electrons and Li ions. As a result, the HGCNS when used as an anode material for lithium ion batteries show high reversible capacity (502 mA h g⁻¹ at 0.1 C), excellent rate capability (461.4, 429.3, 305.2, and 161.4 mA h g⁻¹ at 1, 2, 5, and 10 C, respectively), and superior cycling performance (215 mA h g⁻¹ at 5 C after 2000 cycles and 139.6 mA h g⁻¹ at 10 C after 3000 cycles). What's more, the relatively flat voltage profiles with a negligible charge/discharge voltage hysteresis of HGCNS would be particularly meaningful for its widespread commercialized application in real lithium ion batteries.

Luffa sponge, as a renewable precursor, is used for the first time to synthesize sulfur-doped microporous carbon (SMPC), which is subsequently rolled into an SMPC interlayer that acts as the polysulfide diffusion inhibitor between a sulfur cathode and separator in a Li–S battery. Instrumental analysis shows that the obtained SMPC possesses a unique microporous carbon framework, large specific surface area (3211.2 m² g⁻¹), high pore volume (1.72 cm³ g⁻¹), good electrical conductivity (1.89 S cm⁻¹) and in situ S-doping (2.72 at%). Due to the special physical properties and chemical ingredients of SMPC, the as-fabricated SMPC interlayer for Li–S batteries can not only facilitate rapid electron and Li ion transfer, but can also effectively sequester dissolved polysulfides through combining strong chemical and physical absorption. Consequently, Li–S batteries containing the SMPC interlayer deliver a high initial reversible capacity (1544.2 mA h g⁻¹ at 0.2C), superior rate capability (781.2 mA h g⁻¹ at 5C), and excellent cycling stability (over 500 cycles at 2C with 0.057% capacity fading per cycle). This eco-friendly, low cost SMPC interlayer can offer an appealing alternative for the commercialized production of Li–S cells.