Novel Lamellar Tetrapotassium Pyromellitic Organic for Robust High‐Capacity Potassium Storage

Abstract

Redox‐active organics are investigation hotspots for metal ion storage due to their structural diversity and redox reversibility. However, they are plagued by limited storage capacity, sluggish ion diffusion kinetics, and weak structural stability, especially for K+ ion storage. Herein, we firstly reported the lamellar tetrapotassium pyromellitic (K4PM) with four active sites and large interlayer distance for K+ ion storage based on a design strategy, where organics are constructed with the small molecular mass, multiple active sites, fast ion diffusion channels, and rigid conjugated π bonds. The K4PM electrode delivers a high capacity up to 292 mAh g−1 at 50 mA g−1, among the best reported organics for K+ ion storage. Especially, it achieves an excellent rate capacity and long‐term cycling stability with a capacity retention of ≈83 % after 1000 cycles. Incorporating in situ and ex‐situ techniques, the K+ ion storage mechanism is revealed, where conjugated carboxyls are reversibly rearranged into enolates to stably store K+ ions. This work sheds light on the rational design and optimization of organic electrodes for efficient metal ion storage.

Efficient K‐Storage of Fe‐Coupled Organic Molecule Anode in Ether‐Based Electrolytes

“…Designing anode materials with more active sites and higher structural capabilities has been continuously pursued to overcome these challenges and develop PIBs with a satisfactory capacity and a long cycle life. Examples include carbon anodes, [8,9] alloying anodes, [10,11] conversion anodes, [12–15] and organic anodes [16,17] …”

“…In general, they can store high capacities at a moderate voltage range below 3 V vs. Li + /Li [22] . In addition, it has been reported that the structural stability of the electrode will be enhanced if the OEMs contains π‐conjugated bonds (such as aromatic rings) [16] . Therefore, a great deal of work is devoted to the electrochemical performance regulation of OEMs.…”