Tailored Redox Kinetics, Electronic Structures and Electrode/Electrolyte Interfaces for Fast and High Energy‐Density Potassium‐Organic Battery

Abstract

Potassium-organic batteries have a great potential for applications in large-scale electricity grids and electric vehicles because of their low cost and sustainability. However, their inferior cycle stability and more importantly low energy density under fast discharge/charge process of organic cathodes limit their applications. This work introduces a simple polymerization processing which enables comprehensive tuning of redox kinetics, electronic structures, and electrode/electrolyte interfaces of the polymer cathodes. With this approach, a potassium-organic battery with an impressive energy density of 113 Wh kg −1 at a high power of 35.2 kW kg −1 is shown which corresponds to a high current density of 147 C and a fully discharge within 10 s. The battery also has impressive cycling stability that a 100% Columbic efficiency is maintained and shows negligible capacity degradation after 1000 cycle at a high current density of 7.35 C. Using the polymer cathode and a dipotassium terephthalate anode, a full battery with superior energy density and cycling stability is demonstrated among all reported all-organic full potassium ion batteries.

Organic Electrode Materials for Non-aqueous K-Ion Batteries

“…PIs contain redox-active aromatic imide monomers that can be used as cathode materials in KIBs. Tong et al [68] have shown that the electrochemical properties of PTCDA-based PIs can (Fig. 7b).…”

Electrolytes and Interphases in Potassium Ion Batteries

“…In comparison, for the concentrated electrolyte systems, the decrease of the LUMO energy levels of anions caused by its interaction with K + ions leads to a preferen tial anion reduction reaction. [32,104,107,171] For example, a thinner anionderived SEI layer was formed in the electrolyte of 2.5 m KPF 6 /DEGDME compared with that in 1 m KPF 6 /DEGDME, thus enhanced performance was achieved on KVOPO 4 and K 1.69 Mn[Fe(CN) 6 ] 0.85 •4H 2 O cathodes. [171] Also the KTFSIbased concentrated electrolytes, such as 5 m KTFSI/DEGDME, 5 m KTFSI/DME and 4 m KTFSI/EC:DEC, allow more TFSIions to reach the interface and can introduce a more compact and thinner SEI layer with a larger amount of inorganic spe cies.…”

Organic Materials as Electrodes in Potassium‐Ion Batteries

“…Although redox kinetics have a significant impact on rate performance, the related research is rare: to date, only one research report by Tong [31] et al is available. They could easily adjust the electrochemical performance and redox kinetics of PTCDA‐based polymers (PTCDA‐ k C ( k =0, 2, 3, 4), 25 , Figure 11) by changing the length of the alkyl chain.…”