Multi‐Functionalized Polymers as Organic Cathodes for Sustainable Sodium/Potassium‐Ion Batteries

Abstract

In this work, we designed and synthesized three novel polymeric cathode materials based on azo and carbonyl groups for Na‐ion and K‐ion batteries. The electrochemical performance of the polymer with a naphthalene backbone structure is better than that with benzene and biphenyl structures due to faster kinetics and lower solubility in the electrolyte. It unravels the rational design principle of extending π‐conjugation aromatic structures in redox‐active polymers to enhance the electrochemical performance. To further optimize the polymeric cathodes, the polymer with a naphthalene backbone structure is mixed with nitrogen‐doped graphene to increase the conductivity and mitigate the dissolution. The resulting cathodes deliver high specific capacity, long cycle life, and fast‐charging capability. Post‐cycling characterizations were employed to study the chemical structure and morphology evolution upon cycling, demonstrating that the active centers (azo and carbonyl groups) in the polymer can undergo reversible redox reactions with Na+/K+ for sustainable alkali‐ion batteries.

Uniform P2-K0.6CoO2 Microcubes as a High-Energy Cathode Material for Potassium-Ion Batteries

“…As illustrated in Figure f–i, green and red represent the K layer and the TM-O layer, respectively, and the KCO microcube before cycling and the KCO microcube after 10 cycles both demonstrate slight lattice distortion or internal stress along the c axis (Figure S13). The unique microcube architecture and high crystallinity can also greatly reduce the interface between the electrolyte and the KCO microcubes, thus minimizing active materials dissolution and parasitic reactions and resulting in high CEs . Moreover, the total density of states of pristine, charged, and discharged K x CoO 2 unveils a semiconductor character of the KCO microcubes (Figure S14).…”

Conjugated Azo Compounds as Active Materials for Rechargeable Sodium‐Metal Batteries with High‐Rate Performance

“…A represents the contact area between the active material and electrolyte, t is the duration of the current pulse, and DE s and DE t are the changes in equilibrium potential and voltage, respectively. [31] In Figure 4(e), the D Na þ values of the charging process are higher than those of the discharging process since there is an activation process in the p-PADA.…”

“…where m B , V M , and M B represent the mass, molar volume, and molecular weight of the active material, respectively. A represents the contact area between the active material and electrolyte, $${{\rm { {\rm \tau}{}}}}$$ is the duration of the current pulse, and $${{\rm { \Delta }}{{\rm { E}}}_{{\rm { s}}}}$$ and $${{\rm { \Delta }}{{\rm { E}}}_{{\rm { {\rm \tau}{}}}}}$$ are the changes in equilibrium potential and voltage, respectively [31] . In Figure 4(e), the $${{{\rm { D}}}_{{{\rm { Na}}}^{{\rm { +}}}}}$$ values of the charging process are higher than those of the discharging process since there is an activation process in the p‐PADA.…”

Organic electrode materials and carbon/small-sulfur composites for affordable, lightweight and sustainable batteries

“…10a) were designed and synthesized for NIBs, KIBs, and rechargeable Al batteries. 78,79 The polymers contain the same azo benzene moiety but three different conjugated structures, a naphthalene ring, a benzene ring, and a diphenyl group in the structure units of imide moieties. All three polymers exhibited charge and discharge behaviors with redox plateaus between 1 V to 3 V in NIBs (Fig.…”