Block-Copolymer-Architected Materials in Electrochemical Energy Storage

The multiscale architecture of electrochemical energy storage (EES) materials critically impacts device performance, including energy, power, and durability. The pore space of nano- to macrostructured electrodes determines mass transport within the electrolyte and defines the effective energy density. The dimensions of the active charge-storing materials can increase stability during cycling by accommodating strains from electrochemical-mechanical coupling while also defining surface area that increases capacitive charge storage, decreases charge-transfer resistance, but also leads to low efficiency and degradation from interfacial reactions. Thus, elucidating and developing a fundamental understanding of these correlations requires materials with precisely tunable nanoscale architectures. Herein, approaches that take advantage of the nanoscale control offered by block copolymer (BCP) self-assembly are reviewed and insights gained from associated nanoscale phenomena observed in EES are highlighted. Systematic studies that use custom-tailored BCPs to reveal fundamental nanostructure-property-performance relationships are emphasized. Importantly, most reports of nanostructured materials utilize low loadings and thin electrodes and results represent mass transfer limitations at the particle scale. However, as cell-level performance involves mass transport over 10-100s of micrometers, recently emerging BCP-based processes are further highlighted, leading to hierarchical meso/macroporous materials needed for creating multiscale structure-performance relationships and next-generation energy storage material architectures. Synthetic approaches for energy storage materials with controlled nanostructures utilizing block copolymer self-assembly that elucidate nanostructure-property-performance relationships are reviewed. The impact of mass transfer in electrodes beyond the sub-micrometer scale to showcase the need for tunable hierarchically porous electrodes is further discussed, and emerging multiscale block copolymer assembly approaches to fabricate such advanced architectures are highlighted.image (c) 2023 WILEY-VCH GmbH

Automated summary

The multiscale architecture of electrochemical energy storage materials plays a critical role in device performance. The pore space of electrodes at nanoscale to macroscale determines mass transport and energy density. The size of charge-storing materials affects stability, capacitive charge storage, charge-transfer resistance, efficiency, and degradation. The use of block copolymer self-assembly provides nanoscale control and insights into the correlations observed in electrochemical energy storage.