In-situ Electropolymerized Bipolar Organic Cathode Material for High-Voltage Sodium Dual-Ion Batteries with Long-Cycle Performances

Abstract

Organic electrode materials offer advantages such as structural tunability and high redox reversibility. However, they still face challenges in pursuing long-term cycling stability and high operating voltage. To address these challenges, a donor-acceptor monomer (TPA-PQ) integrating phenanthrenequinone (n-type) and triphenylamine (p-type) units is synthesized, which then undergoes in-situ electropolymerization to form a bipolar cathode material pTPA-PQ for SIBs. The in-situ electropolymerization significantly enhances structural stability and cycle performances. As a result, the pTPA-PQ electrode exhibits a high average voltage of 3.15 V, as well as a remarkable energy density of 441 Wh·kg^–1. Notably, the average voltage achieved represents one of the highest values reported in bipolar organic electrode materials. More importantly, the pTPA-PQ electrode demonstrates excellent stability even after 10,000 cycles in a half-cell, with an average capacity decay rate of only 0.0032% per cycle. Furthermore, symmetric all-organic full cells based on pTPA-PQ achieve a high energy density of 173.8 Wh·kg^–1 and maintain stable cycling over 2,000 cycles even at a high C-rate of 6 C. This work provides a feasible pathway for developing high-performance organic electrode materials for sodium-ion batteries.

Keywords

Electropolymerization / Organic cathode / Operating voltage / Cycling stability / Symmetric-cell / C–C coupling / Molecular electrochemistry / Donor-acceptor systems

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