Rethinking the Design of Ionic Conductors Using Meyer–Neldel–Conductivity Plot. Issue 13 (28th February 2021)

• Record Type: Journal Article
• Authors: Gao, Yirong; Li, Nana; Wu, Yifan; Yang, Wenge; Bo, Shou‐Hang
• Is Part Of: Advanced energy materials. Volume 11:Issue 13(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-02-28
• Subjects: activation energy -- high ionic conductivity -- Meyer–Neldel rule -- solid‐state ionic conductors; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202100325
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: From the discovery of the first fast ionic conductor silver iodide in the early 20th century to the recent discovery of lithium fast ionic conductors with ionic conductivities surpassing those of liquid electrolytes, high ionic conductivity σ has often been associated with low activation energy E a following the Arrhenius equation. However, the Meyer–Neldel rule (MNR) indicates that the E a and prefactor σ0 are correlated, suggesting the relation between the E a and σ is, in fact, complex. In this perspective, the use of the Meyer–Neldel–conductivity plot and a critical descriptor, Meyer–Neldel energy Δ0, to guide the search for fast ionic conductors is proposed. Reported lithium, sodium, and magnesium ionic conductors are categorized into three types, depending on the relative magnitude between the Δ0 and thermal energy ( k B T ) at the application temperature. The process by which σ can be optimized by tuning E a for these types of ionic conductors is elaborated. This principle can be widely applied to all ionic conductors that obey the MNR at any application temperature. Furthermore, a pressure‐tuning approach to measure the Δ0 rapidly is developed. These findings establish a previously missing step for designing new ionic conductors with improved ionic conductivity. Abstract : Decreased activation energy is not always beneficial for achieving high ionic conductivity. Instead, ionic conductors can be categorized into three different types according to the relative magnitude between Meyer–Neldel energy and the thermal energy at the application temperature. A refined design principle of ionic conductors is proposed, revealing how the activation energy should be tuned for the optimized ionic conductivity.