Architectural Strategies for Active Material Ratio Enhancement in High-Energy Organic Batteries

Abstract

Redox-active organic electrode materials (OEMs) are viewed as promising, sustainable substitutes for traditional transition metal-based cathodes, yet their application is fundamentally restricted by their intrinsic, low electronic conductivity. Existing methodologies for improvement, such as the incorporation of an excessive volume of conductive additives or the synthesis of advanced organic molecules, typically result in the dilution of active material content to around 60 wt%, consequently sacrificing energy density, or introduce major obstacles to industrial scalability. This investigation addresses these fundamental limitations by implementing a systematic optimization of the composite's internal carbon-binder domain (CBD) network. Our novel approach involves a synergistic combination of one-dimensional multi-walled carbon nanotubes (MWCNTs) with the conductive polymer poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), successfully creating efficient pathways for both electronic and ionic transport. This highly effective formulation allows perylene- 3,4,9,10-tetracarboxylic dianhydride (PTCDA) electrodes, incorporating a high 90 wt% active material ratio, to achieve a discharge capacity of 118.7 mAh g-1 at an aggressive current density of 1 A g-1, maintaining 99% capacity retention over 300 cycles—performance unobtainable by conventional Super P–PVDF (SP-F) electrodes, which fail under the same conditions. Analysis of the percolation behavior pinpointed 95 wt% as the definitive critical active material threshold, resulting in a calculated specific energy of 248 Wh kg-1 (representing a 39% enhancement). Furthermore, the practical feasibility was confirmed using large-area pouch cells (12 cm2) featuring thin lithium metal anodes (40 um), which preserved robust cyclability (85% retention) even at high operational rates. Crucially, the engineering design proved broadly applicable across structurally diverse organic materials, including anthraquinone and dilithium rhodizonate, consistently delivering superior performance compared to standard SP-F formulations. These outcomes strongly demonstrate that focusing research efforts on electrode-level engineering is vital for fully realizing the intrinsic energy density advantages offered by organic battery systems.