Nitro-substituted aromatic compounds for use in electrodes

A secondary battery comprises a secondary battery cathode,

• wherein the secondary battery cathode comprises as a cathode active material a nitro-substituted aromatic compound,
• wherein one or more nitro groups of the nitro-substituted aromatic compound provide reversible redox-active functionality, and
• wherein the nitro-substituted aromatic compound is of formula (I), (II), (III), or (IV):
• or a copolymer comprising repeat units of formula (III) and/or (IV),
• wherein:
• A represents an arene or heteroarene,
• B represents an aromatic carbon allotrope, which is optionally doped with one or more heteroatoms,
• R1 represents one or more -L-NO2 substituents,
• wherein in case that the nitro-substituted aromatic compound is of formula (I), R1 represents at least two -L-NO2 substituents;
• R2 represents ═N—, ═CH—, or ═CR5—, and
• R3 and R4 independently represent a hydrogen atom or R5
• wherein L represents a covalent bond or a linking group, and
• wherein each —R5 independently represents R6,—X, —NH2, —NR6H, —NR62, —CN, —CHO, —COOH, —COOR6, —COO−M+, —OH, —OR6, or —O−M+ group, in which:
• R6 represents an alkyl, alkenyl, alkynyl, aryl, or heteroaryl group, M represents a metal ion, and X represents a halogen atom;
• wherein A and B are substituted by one or more R5 substituents.