Poly(pentacenetetrone) as a High-capacity Cathode for Sodium Batteries

Sodium batteries (SBs) are a promising alternative to lithium-ion batteries (LIBs) due to the abundance, cost-effectiveness, and environmental sustainability of sodium. However, the larger ionic radius of Na⁺ leads to challenges in electrode stability, limiting the performance of conventional inorganic cathode materials. Redox-active organic compounds, particularly π-conjugated quinones, have emerged as a viable alternative, due to their tunable electrochemical properties, structural flexibility, and enhanced compatibility with Na⁺. Despite their advantages, many quinone-based cathodes suffer from limited cycling stability and solubility issues. Here, the synthesis and characterization of poly(pentacenetetrone) (PPT) as a high-capacity cathode material for SBs is reported. PPT exhibits a high theoretical specific capacity (Q_tsp = 319 mAh g⁻¹) and achieves an experimental specific capacity (Q_sp) of 314 mAh g⁻¹ at 0.2C, with remarkable cycling stability. At 2C, the capacity remains at 260 mAh g⁻¹, retaining 92% after 500 cycles. PPT demonstrates excellent rate capability with 98% capacity retention after extended cycling. These findings highlight the potential of PPT as a high-performance cathode material for sodium batteries, addressing critical challenges in scalability and long-term stability for next-generation energy storage systems.