Abstract
Among other things, battery electrodes need to display large absolute capacities coupled with high rate performance. However, enhancing areal capacity, for example via increased electrode thickness, results in reductions in rate performance. The basis for this negative correlation has not been studied in a quantitative fashion. Here, a semiempirical model is used to analyze capacity versus rate data for electrodes fabricated from a number of materials, each measured at various thicknesses. Fitting the model to the data outputs the low-rate areal capacity, QA, and the characteristic time associated with charge/discharge, τ, fit parameters which quantify absolute capacity and rate performance respectively. A clear correlation is found between QA and τ, with all data siting close to a mastercurve approximately defined by constant τ/QA. This data is consistent with a simple model based on the timescales associated with rate-limiting processes. This model implies that the capacity-rate trade-off can be improved for high areal capacity electrodes by increasing the volumetric capacity, electrical conductivity, and porosity of the electrode. Conversely, solid-state diffusion and reaction kinetics are only important for low areal capacity electrodes.
Original language | English |
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Article number | 1901359 |
Journal | Advanced Energy Materials |
Volume | 9 |
Issue number | 33 |
DOIs | |
State | Published - 1 Sep 2019 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Funding
S.-H.P., R.T., and J.C. contributed equally to this work. All authors acknowledge the SFI-funded AMBER research centre (SFI/12/RC/2278) and Nokia for support. J.N.C thanks Science Foundation Ireland (SFI, 11/PI/1087), the Graphene Flagship (Grant Agreement No. 785219) and the ERC (Adv. Gr. FUTUREPRINT) for funding. V.N. thanks the European Research Council (SoG 3D2D Print) and Science Foundation Ireland (PIYRA) for funding.
Funders | Funder number |
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PIYRA | |
Nokia | |
Horizon 2020 Framework Programme | 681544, 785219 |
European Commission | |
Science Foundation Ireland | 11/PI/1087 |
Keywords
- areal capacity
- energy density
- power density
- rate performance