Mitigating Dissolution to Enhance the Performance of Pillar[5]quinone in Sodium Batteries

Sodium‐ion batteries using organic electrode materials are a promising alternative to state‐of‐the‐art lithium‐ion batteries. However, their practical viability is hindered by challenges such as a low specific capacity of the organic electrode materials, or their dissolution in the electrolyte. We herein present a double mitigation strategy to enhance the performance of pillar[5]quinone (P5Q) as positive electrode material in sodium batteries. Using 5 m sodium bis(fluorosulfonyl)imide in succinonitrile as highly concentrated electrolyte, as well as encapsulating P5Q in CMK‐3 (Carbon Mesostructured by KAIST with hexagonally ordered rod‐like carbon domains) as templated ordered mesoporous carbon, we achieve a record cycling performance with improved cycling stability even at elevated temperature (40 °C). The P5Q@CMK‐3 composite electrode delivers 430 mAh g −1 specific discharge capacity at 0.2 C rate with 90 % retention over 200 cycles. This corresponds to an energy density of 831 Wh kg −1 (based on P5Q mass) and surpasses previous reports on pillarquinones. When operated at 40 °C, the P5Q@CMK‐3 composite electrodes deliver a specific discharge capacity of 438 mAh g −1 with 88 % capacity retention over 500 cycles (0.02 % per cycle). This study underscores the crucial role the electrolyte plays in advancing organic sodium batteries, offering a promising avenue for the future of sustainable energy technologies.