Fig.1

(a) ragone plots of normal electrochemical energy storage devices; (b) illustration of mechanism of the charge/discharge process involved in Li-S batteries; (c) typical charge/discharge curves of the first cycle involved in Li-S batteries"

Table 1

The capacity contribution of different DOD"

Fig.2

The structure cognitive process of S@PAN: (a) the possible molecular structure of S@PAN according to Buchmeiser et al. in 2011; (b) the revised S@PAN structure based on C/H element ratio by Zhang et al. in 2014; (c) the possible molecular structure of S@PAN according to Archer et al. in 2015; (b) the demonstrated S@PAN structure based on the integration of 13C Solid State Nuclear Magnetic Resonance as well as quantum chemistry simulation by Ming et al. in 2018"

Fig.3

The cognitive process of S@PAN reaction mechanism: (a) the possible reaction mechanism of S@PAN according to Wang et al. in 2013; (b) the reaction mechanism of S@PAN based on SS-NMR and ex-situ XPS by Yang et al. in 2018; (c) the integration of 7Li solid state nuclear magnetic resonance as well as quantum chemistry simulation by Ming et al. in 2018"

Fig.4

Design and construct the new S@PAN energy storage system: (a) the introduction of Se into S@PAN system to enhance the fast redox reaction, and further improve the reaction kinetics by Xie et al; (b) Liu et al. in 2019 introduce the CNTs to design 3D conductive network via electrostatic spinning, and further improve the reaction kinetics"

Fig.5

The preparation of unsaturated hydrocarbon derived organic sulfur electrode: (a) synthetic scheme for the first copolymerization of S8 with DIB to form chemically stable sulfur copolymers by Pyun et al. in 2013; (b) schematic illustration from DEB with S8 to form copolymer by Meng et al. in 2014; (c) schematic illustration from ProDOT-Sty with S8 to form copolymer to enhance both conductivity and sulfur loadings by Pyun et al. in 2015; (d) synthetic approach for the copolymerization P3HT with S8 and proposed microstructure of the copolymer-containing sample by Zentel et al. in 2015"

Fig.6

The preparation of thiol group derived organic sulfur electrode: (a) synthetic scheme for the first copolymerization of S8 with TTCA to form chemically stable sulfur copolymers via soft-templates by Park et al. in 2015; (b) schematic illustration to form sulfur rich S-BOP copolymer through one pot method by Choi et al. in 2016; (c) schematic illustration to immobilize sulfur on the adsorbed base via reverse vulcanization by Chen et al. in 2018"

Fig.7

The preparation of micro-molecules organic sulfur electrode: (a) theoretical specific capacity of various micro-molecules of sulfur (b) PMTT as high performance Li-S cathode by Fu et al. in 2017; (c) a crosslinked polymer of one benzene ring unit with six sulfur atoms reported by Preefer et al. in 2017; (d) 2019, Long et al. synthesis of single crystal TTT and HTP via intermittent heating strategy"

Fig.8

The high performance Li-S cathodes derived from polymer"