Electrochemical Thin Layers in Nanostructures for Energy Storage

Malachi Noked, Chanyuan Liu, Junkai Hu, Keith Gregorczyk, Gary W. Rubloff, Sang Bok Lee

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

ConspectusConventional electrical energy storage (EES) electrodes, such as rechargeable batteries, are mostly based on composites of monolithic micrometer sized particles bound together with polymeric and conductive carbon additives and binders. The kinetic limitations of these monolithic chunks of material are inherently linked to their electrical properties, the kinetics of ion insertion through their interface and ion migration in and through the composite phase. Redox chemistry of nanostructured materials in EES systems offer vast gains in power and energy. Furthermore, due to their thin nature, ion and electron transport is dramatically increased, especially when thin heterogeneous conducting layers are employed synergistically. However, since the stability of the electrode material is dictated by the nature of the electrochemical reaction and the accompanying volumetric and interfacial changes from the perspective of overall system lifetime, research with nanostructured materials has shown often indefinite conclusions: in some cases, an increase in unwanted side-reactions due to the high surface area (bad). In other cases, results have shown significantly better handling of mechanical stress that results from lithiation/delithiation (good). Despite these mixed results, scientifically informed design of thin electrode materials, with carefully chosen architectures, is considered a promising route to address many limitations witnessed in EES systems by reducing and protecting electrodes from parasitic reactions, accommodating mechanical stress due to volumetric changes from electrochemical reactions, and optimizing charge carrier mobilities from both the "ionic" and "electronic" points of view. Furthermore, precise nanoscale control over the electrode structure can enable accurate measurement through advanced spectroscopy and microscopy techniques.This Account summarizes recent findings related to thin electrode materials synthesized by atomic layer deposition (ALD) and electrochemical deposition (ECD), including nanowires, nanotubes, and thin films. Throughout the Account, we will show how these techniques enabled us to synthesize electrodes of interest with precise control over the structure and composition of the material. We will illustrate and discuss how the electrochemical response of thin electrodes made by these techniques can facilitate new mechanisms for ion storage, mediate the interfacial electrochemical response of the electrode, and address issues related to electrode degradation over time. The effects of nanosizing materials and their electrochemical response will be mechanistically reviewed through two categories of ion storage: (1) pseudocapacitance and (2) ion insertion. Additionally, we will show how electrochemical processes that are more complicated because of accompanying volumetric changes and electrode degradation pathways can be mediated and controlled by application of thin functional materials on the electrochemically active interface; examples include conversion electrodes, reactive lithium metal anodes, and complex reactions in a Li/O2 cathode system. The goal of this Account is to illustrate how careful design of thin materials either as active electrodes or as mediating layers can facilitate desirable interfacial electrochemical activity and resolve or shed light on mechanistic limitations of electrochemical processes related to micrometer size particles currently used in energy storage electrodes.

Original languageEnglish
Pages (from-to)2336-2346
Number of pages11
JournalAccounts of Chemical Research
Volume49
Issue number10
DOIs
StatePublished - 18 Oct 2016
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

Funding

This work has been supported by Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by U.S Department of Energy,Office of Science,Office of Basic Energy Sciences, under Award Number DESC0001160.

FundersFunder number
Nanostructures for Electrical Energy Storage
U.S. Department of Energy
Office of Science
Basic Energy SciencesDESC0001160

    Fingerprint

    Dive into the research topics of 'Electrochemical Thin Layers in Nanostructures for Energy Storage'. Together they form a unique fingerprint.

    Cite this