Understanding Rapid Intercalation Materials One Parameter at a Time. (1st June 2022)

• Record Type: Journal Article
• Authors: van den Bergh, Wessel; Stefik, Morgan
• Is Part Of: Advanced functional materials. Volume 32:Number 31(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-06-01
• Subjects: battery -- intercalation -- kinetics -- nanomaterials -- pseudocapacitance; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202204126
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Demand for fast, energy‐dense storage drives the research into nanoscale intercalation materials. Nanomaterials accelerate kinetics and can modify reaction path thermodynamics, intercalant solubility, and reversibility. The discovery of intercalation pseudocapacitance has opened questions about their fundamental operating principles. For example, are their capacitor‐like current responses caused by storing energy in special near‐surface regions or rather is this response due to normal intercalation limited by a slower faradaic surface‐reaction? This review highlights emerging methods combining tailored nanomaterials with the process of elimination to disambiguate cause‐and‐effect at the nanoscale. This method is applied to multiple intercalation pseudocapacitive materials showing that the timescales exhibiting surface‐limited kinetics depended on the total intercalation length scale. These trends are inconsistent with the near‐surface perspective. A revised current‐model without assuming special near‐surface storage fits experimental data better across wide timescales. This model, combined with tailored nanomaterials and the process of elimination, can isolate material‐specific effects such as how amorphization/defect‐tailoring modifies both insertion and diffusion kinetics. Avenues for both faster intercalation pseudocapacitance and increased energy density are discussed. A relaxation time argument is suggested to explain the continuum between battery‐like and pseudocapacitive behaviors. Future directions include synthetic methods emphasizing tailored defects and analytical methods that minimize assumptions. Abstract : The discovery of intercalation pseudocapacitance has opened questions about fundamental operating principles. This review highlights emerging methods combining tailored nanomaterials with the process‐of‐elimination to disambiguate cause‐and‐effect. Presented examples are most consistent with the Insert‐Intercalate perspective and are rationalized with length scale dependencies of surface/diffusion time constants. Inconsistencies of the near‐surface perspective and the notion of intrinsic intercalation pseudocapacitance are discussed.