Lithium–sulfur (Li–S) batteries with high energy density are considered as promising for rechargeable energy storage. However, the shuttle effect hinders their practical application. Here, novel nitrogen-doped micro-/mesoporous carbon (N-MIMEC), derived from crab shells, was fabricated via a sustainable and cost-effective route. A modified separator coated with an N-MIMEC layer for Li–S batteries exhibits many advantages: (1) the micro-/mesopores provide enough surface area for sulfide adsorption, and accommodate the volume change; (2) the nitrogen in N-MIMEC enhances polysulfide adsorption and increases the electronic conductivity of the carbon framework; and (3) the conductive layer acts as an upper current collector, increasing the electrical conductivity. An enhanced Li–S battery with an N-MIMEC-coated separator was constructed, with an initial capacity of 1301 mA h g⁻¹ and a high reversible capacity of 971.3 mA h g⁻¹ after 100 cycles at 0.1C. Also, upon further increasing the sulfur loading from 63 wt% to 77 wt%, the corresponding Li–S batteries exhibit a high reversible capacity of 578 mA h g⁻¹ after 500 cycles at 1C, with a decay rate of about 0.029% per cycle. Considering the green and sustainable source material, simple preparation and good electrochemical performance, the N-MIMEC-coated separator is promising for Li–S battery applications.

Chitosan with abundant hydroxyl and amine groups as an additive for cathodes and separators has been proven to be an effective polysulfide trapping agent in lithium–sulfur batteries. Compared with common sulfur cathodes, the cathode with chitosan shows an enhanced initial discharge capacity from 950 to 1145 mA h g⁻¹ at C/10. The reversible specific capacity after 100 cycles increases from 508 mA h g⁻¹ to 680 mA h g⁻¹ and 473 to 646 mA h g⁻¹ at rates of C/2 and 1 C, respectively. In addition, batteries with separators that are coated with a carbon/chitosan layer can exhibit a high discharge capacity of 830 mA h g⁻¹ at C/2 after 100 cycles and 675 mA h g⁻¹ at 1 C after 200 cycles with the capacity fading to as low as 0.11% per cycle. This study demonstrates the benefits of using chitosan for not only lithium–sulfur batteries but also potentially other sulfur-based battery applications.

Drug delivery nanosystems (DDnS) is widely developed recently. Gelatin is a high-potential biomaterial originated from natural resources for anticancer DDnS, which can effectively improve the utilization of anticancer drugs and reduce side effects. The hydrophilic, amphoteric behavior and sol-gel transition of gelatin can be used to fulfill various requirements of anticancer DDnS. Additionally, the high number of multifunctional groups on the surface of gelatin provides the possibility of crosslinking and further modifications. In this review, we focus on the properties of gelatin and briefly elaborate the correlation between the properties and anticancer DDnS. Furthermore, we discuss the applications of gelatin-based DDnS in various cancer treatments. Overall, we have summarized the excellent properties of gelatin and correlated with DDnS to provide a manual for the design of gelatin-based materials for DDnS.