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 in sodium batteries. Using 5 M sodium bis(fluorosulfonyl)imide in succinonitrile as highly concentrated electrolyte, and 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 0.2C 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.