Tunable Electric Double-Layer Capacitor Performance through Engineered Charge Patterns in Polyelectrolytes

Understanding how charge fraction and sequence in polyelectrolytes (PEs) affect electric double-layer capacitors (EDLCs) is crucial for optimizing energy storage devices. We employed antisymmetric PEs composed of polycations and polyanions with identical charge patterns, eliminating counterion effects and focusing on intrinsic PE–electrode interactions. Our simulations revealed that increasing the charge fraction enhances differential capacitance due to more charged species facilitating efficient charge storage. Block-patterned PEs, where charged beads are grouped along the polymer chain, exhibited higher integral capacitance than regular-patterned PEs and simple electrolytes but resulted in slower charging rates due to substantial conformational adjustments during adsorption. Both types of PEs promoted enhanced overscreening, increasing the charge accumulation near the electrode surface. These findings highlight the significant impact of the charge fraction and sequence on the EDLC performance. Careful selection of PE charge patterns can thus tailor energy storage capacities and charging rates to meet specific application needs.