Soluble Organic Cathodes Enable Long Cycle Life, High Rate, and Wide‐Temperature Lithium‐Ion Batteries

Abstract

Organic electrode materials free of rare transition metal elements are promising for sustainable, cost‐effective, and environmentally benign battery chemistries. However, severe shuttling effect caused by the dissolution of active materials in liquid electrolytes results in fast capacity decay, limiting their practical applications. Here, using a gel polymer electrolyte (GPE) that is in situ formed on Nafion‐coated separators, the shuttle reaction of organic electrodes is eliminated while maintaining the electrochemical performance. The synergy of physical confinement by GPE with tunable polymer structure and charge repulsion of the Nafion‐coated separator substantially prevents the soluble organic electrode materials with different molecular sizes from shuttling. A soluble small‐molecule organic electrode material of 1,3,5‐tri(9,10‐anthraquinonyl)benzene demonstrates exceptional electrochemical performance with an ultra‐long cycle life of 10 000 cycles, excellent rate capability of 203 mAh g−1 at 100 C, and a wide working temperature range from −70 to 100 °C based on the solid–liquid conversion chemistry, which outperforms all previously reported organic cathode materials. The shielding capability of GPE can be designed and tailored toward organic electrodes with different molecular sizes, thus providing a universal resolution to the shuttling effect that all soluble electrode materials suffer.

Synthetic Control of Electronic Property and Porosity in Anthraquinone-Based Conjugated Polymer Cathodes for High-Rate and Long-Cycle-Life Na–Organic Batteries

“…A superior rate performance with high capacity retention was obtained by both PBAQ-1 and PBAQ-3, albeit the PBAQ-1 cathode has a lower capacity than PBAQ-3 at the same currents. The high rate capability for PBAQ-1 might be associated with its dissolution nature in the electrolyte at the discharged state, which enables PBAQ-1 to undergo a “solid–liquid” conversion with fast kinetics during the redox reaction . In the case of PBAQ-3, its excellent rate capability should originate from the narrow band gap and high surface area that are advantageous in facilitating the charge (Na + and electron) transfer during the sodiation/desodiation processes.…”

In situ prepared “polymer-in-salt” electrolytes enabling high-voltage lithium metal batteries

“…† It can be observed that M n of the PISE is the lowest and one quarter less than that of pure PCA, which is favorable for ionic conductivity. 38,39 Electrochemical properties of electrolytes…”

Challenges and advances of organic electrode materials for sustainable secondary batteries

“…[99] However, recent researches show that some organic salts still experience inferior cycling stability in the aprotic electrolyte due to their structure changes during the battery operation, which suggests the limitation of the organic salts strategy. [100][101][102] Second, optimizing the electrolyte is an effective method to enhance cycle stability of the overall battery, including regulated electrolyte, ionic liquid electrolyte, solid-state…”