A 3.8 V Quaternary Ammonium-Based Dual-Ion Battery Enabled by a Conjugated Ladder Polymer

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Nonmetal rechargeable batteries, particularly ammonium (NH₄⁺)-based systems, offer safety and cost benefits but are limited by narrow electrochemical windows.
• Developing high-voltage electrolytes is crucial for enhancing energy density in next-generation batteries.
• Quaternary ammonium (NR₄⁺) ions present a potential alternative for improved battery performance.

Purpose of the Study:

• To develop a high-voltage dual-ion battery (DIB) utilizing quaternary ammonium (NR₄⁺) ions.
• To investigate the performance of a conjugated ladder polymer, poly(benzobisimidazobenzophenanthroline) (BBL), as an anode for NR₄⁺ storage.
• To demonstrate the feasibility of NR₄⁺ as a charge carrier in high-performance nonmetallic energy storage devices.

Main Methods:

• A dual-ion battery (DIB) was constructed using a BBL polymer anode for NR₄⁺ storage and a graphite cathode for anion intercalation.
• Electrochemical performance, including capacity, voltage, rate capability, and cycling stability, was evaluated.
• The redox mechanism of the BBL anode, involving carbonyl/enol transformation and radical anion formation, was studied.

Main Results:

• The assembled graphite//BBL DIB operates at a high voltage of 3.8 V.
• The BBL anode exhibits a high capacity of 120 mAh g^-1, excellent stability, and good rate performance.
• The DIB achieved a maximum energy density of 232 Wh kg^-1 and power density of 6865 W kg^-1 with remarkable cycling stability.

Conclusions:

• Quaternary ammonium (NR₄⁺) ions can be effectively utilized as charge carriers in high-voltage DIBs.
• The conjugated ladder polymer BBL serves as an efficient anode material for NR₄⁺ storage, enabling high energy and power densities.
• This research paves the way for novel designs of high-performance nonmetallic energy storage devices.