Novel Insoluble Organic Cathodes for Advanced Organic K‐Ion Batteries

Abstract

Organic redox-active molecules are inborn electrodes to store large-radius potassium (K) ion. High-performance organic cathodes are important for practical usage of organic potassium-ion batteries (OPIBs). However, smallmolecule organic cathodes face serious dissolution problems against liquid electrolytes. A novel insoluble small-molecule organic cathode [N,N′-bis(2anthraquinone)]-perylene-3,4,9,10-tetracarboxydiimide (PTCDI-DAQ, 200 mAh g −1 ) is initially designed for OPIBs. In half cells (1-3.8 V vs K + /K) using 1 m KPF 6 in dimethoxyethane (DME), PTCDI-DAQ delivers a highly stable specific capacity of 216 mAh g −1 and still holds the value of 133 mAh g −1 at an ultrahigh current density of 20 A g −1 (100 C). Using reduced potassium terephthalate (K 4 TP) as the organic anode, the resulting K 4 TP||PTCDI-DAQ OPIBs with the electrolyte 1 m KPF 6 in DME realize a high energy density of maximum 295 Wh kg −1 cathode (213 mAh g −1 cathode × 1.38 V) and power density of 13 800 W Kg −1 cathode (94 mAh g −1 × 1.38 V @ 10 A g −1 ) during the working voltage of 0.2-3.2 V. Meanwhile, K 4 TP||PTCDI-DAQ OPIBs fulfill the superlong lifespan with a stable discharge capacity of 62 mAh g −1 cathode after 10 000 cycles and 40 mAh g −1 cathode after 30 000 cycles (3 A g −1 ). The integrated performance of PTCDI-DAQ can currently defeat any cathode reported in K-ion half/full cells.

Electrochemical Study of Poly(2,6‐Anthraquinonyl Sulfide) as Cathode for Alkali‐Metal‐Ion Batteries

“…[9][10][11] Therefore, organic materials as electrodes applied for metal-ion batteries have fascinated researchers gradually in recent years. [8,[12][13][14] Lithium-ion batteries (LIBs) have been widely applied in electron devices and electric vehicles due to its high energy density. [15] Meanwhile, there is also an increasing attention on sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) that are potentially comparable to LIBs due to their low cost and abundant resources.…”

Covalent Organic Frameworks for Next‐Generation Batteries

“…Therefore, organic electrode materials are one potential candidate electrode materials for high-performance PIBs. [58][59][60] The structure and pores of COFs can be adjusted by introducing different functional groups, which provides a possibility for them to be used as electrode materials for potassium ion batteries. [61][62][63] To a certain extent, the size effect of the porous structure of a COF determines its K ion storage behavior.…”

“…Unlike inorganic electrode materials, organic electrode materials can provide more active sites and transmission channels for potassium storage due to their good structural adjustability and open‐pore channels. Therefore, organic electrode materials are one potential candidate electrode materials for high‐performance PIBs . The structure and pores of COFs can be adjusted by introducing different functional groups, which provides a possibility for them to be used as electrode materials for potassium ion batteries …”

Post‐Lithium‐Ion Battery Era: Recent Advances in Rechargeable Potassium‐Ion Batteries

“…Moreover, Fan et al. designed a novel, insoluble, organic cathode, [ N , N ′‐bis(2‐anthraquinone)]perylene‐3,4,9,10‐tetracarboxydiimide, that delivered a high capacity of 133 mAh g −1 at an ultrahigh current density of 20 Ag −1 [175] . Electrode materials that can maintain a high capacity at an ultrahigh current density are urgently needed and require further development.…”