Fig 1

Development history of organic electrode materials."

Table 1

Characteristics and applications of organic electrode materials."

Fig 2

Redox mechanism of organic electrode materials."

Fig 3

(a) HOMO/LUMO energy levels of DTN, AQ, TTE and NLC92; (b) molecular structure and HOMO/LUMO energy levels of HATN, HATNPF12 and HATNPF2293; (c) summary of basic properties of common organic electrode materials."

Fig 4

Modification strategies of OEMs."

Table 2

Effects of different substituents and representative organic molecular structures."

Fig 5

(a) Structural formula, redox process and electrochemical performance of conjugated system extension (−)-NDI-Δ and monomer derivative NDI-Ref. 106; (b) synthetic routes of BBQ, BBQB, TBQB and corresponding electrochemical properties107; (c) the chemical structure of SBDC and three possible extended π-conjugated structures and molecular packing diagram of SSDC108."

Fig 6

(a) The optimized geometries of the four materials: AQ, PAQS, P14AQ, and P15AQ and cycle profiles at a current density of 0.2C and long cycle profiles of P14AQ at a current density of 1C and 2C112; (b) The synthesis scheme of polymers EDP, HP and UP113; (c) Structures of polymers containing BQ and NQ, synthetic routes of poly(NBE-BQ) and poly(NBE-NQ)114."

Fig 7

(a) Synthesis, energy storage mechanism and electrochemical performance of 2D-PAI@CNT135; (b) graphical representation of COF@CNTs with few COF layers covered on the exterior surface of CNTs141; (c) the synthesis strategy, morphological characterization and cycle performance of PMTA/SWCNT142."

Fig 8

(a) Scheme of the synthesis process of PC/G composites and the corresponding cycle performance151; (b) schematic illustration of the synthesis of VG 8/G composite and the corresponding cycle performance153; (c) schematic illustration of the formation of Na2TP@GE and the corresponding cycle performance154; (d) schematic diagram of in situ braided GDY nanocoatings and the corresponding cycle performance156."

Fig 9

(a) Fabrication process of C6Cl4O2/CMK composite and its electrochemical properties and cycle performance159; (b) preparation of H2bhnq/CMK-3 composites and schematic diagram of electrochemical performance160."

Fig 10

SEM images and electrochemical properties of CADS with different sizes: (a) micropillar; (b) microwire; (c) nanowire; (d) cycle life; (e) rate capability163."

Fig 11

(a) The schematic redox reaction mechanisms of PT and P33DT165; (b) structural diagrams of four conjugated ladder polymers; (c) electrochemical performance of CLP-HAT in potassium ion batteries and morphological characterization169."

Fig 12

(a) Schematic diagram of layer-by-layer stacking of 2D-COF with different thicknesses and corresponding electrochemical performance170; (b) schematic illustration for the exfoliation of 2D redox-Active COF into exfoliated COF as cathodes for lithium ion battery122; (c) exfoliation of COF-43 yields a suspension of few-layer 2D polymers171."

Fig 13

(a) The physical and chemical properties of different electrolytes and the electrochemical performance of PI-1/CNT as electrode materials174; (b) HOMO and LUMO energy levels of different solvents and salts175; (c) interaction and cycle performance of PBALS in liquid and solid electrolytes176."

Fig 14

(a) Schematic diagram of PTCDA/rGO synthesis process and electrochemical performance179; (b) schematic diagram of the synthesis process and electrochemical performance of PQANPs180."

Fig 15

(a) Capacity–voltage and (b) current density–capacity diagrams of partially modified organic electrode materials."

Fig 16

OEM modified target."

Table 3

Representative OEM with excellent long cycle performance."