The thermodynamics, kinetics and modelling of fast-charging lithium-ion batteries featuring crystallographic shear niobium metal oxide anodes
type: CreativeWork
description: The world increasingly depends on batteries to store renewable energy and use that same energy in our vehicles and portable communication devices. This puts exceeding pressure on global resources. We need batteries that charge faster and live longer, such that we can use less resources. Faster charge and longer life are currently limited by the negative electrode, typically graphite, because fast charging would push the potential into the regime of hazardous and cycle-life degrading lithium plating. The ideal potential for fast charge would be low, but just above the around 1 V reduction potential of the electrolyte. Niobium-based metal oxides have the optimal electronegativity to strike this balance, with a nominal potential around 1.6 V, charging rates >5C and a cycle-life projected over 10,000 cycles. Chapter 1 shows that the exact potential can be tuned further by changing the average oxidation state through substitution of Nb5+ with for example W6+ or Ti4+. The range of average oxidation states then directly spans a material phase space classed by anion-to-cation ratios of 2.33 ≤ *y* < 2.82. These "off-stoichiometric" ratios typically force the unit cell to rearrange into an ordered balance of *y*=3 ReO3-type blocks of corner-sharing octahedra that have ample window sites to rapidly intercalate many lithium-ions, interspaced with *y*=2.5 crystallographic shear planes of edge-sharing octahedra that add stability and electronic conductivity to the structure, and anchored at their corner by *y*=2 regions of tetrahedra or edge-sharing octahedra. The influence of this structure on cell performance is relatively unknown. Numerous publications exist on individual members of this Wadsley-Roth (WR) material family, but gaps in theory and varying experimental conditions make it impossible to compare. The aim of this thesis is to provide a fair and fundamental comparison across this material class, relating compositional and structural properties to cell thermodynamics an…
abstract: The world increasingly depends on batteries to store renewable energy and use that same energy in our vehicles and portable communication devices. This puts exceeding pressure on global resources. We need batteries that charge faster and live longer, such that we can use less resources. Faster charge and longer life are currently limited by the negative electrode, typically graphite, because fast charging would push the potential into the regime of hazardous and cycle-life degrading lithium plating. The ideal potential for fast charge would be low, but just above the around 1 V reduction potential of the electrolyte. Niobium-based metal oxides have the optimal electronegativity to strike this balance, with a nominal potential around 1.6 V, charging rates >5C and a cycle-life projected over 10,000 cycles. Chapter 1 shows that the exact potential can be tuned further by changing the average oxidation state through substitution of Nb5+ with for example W6+ or Ti4+. The range of average oxidation states then directly spans a material phase space classed by anion-to-cation ratios of 2.33 ≤ *y* < 2.82. These "off-stoichiometric" ratios typically force the unit cell to rearrange into an ordered balance of *y*=3 ReO3-type blocks of corner-sharing octahedra that have ample window sites to rapidly intercalate many lithium-ions, interspaced with *y*=2.5 crystallographic shear planes of edge-sharing octahedra that add stability and electronic conductivity to the structure, and anchored at their corner by *y*=2 regions of tetrahedra or edge-sharing octahedra. The influence of this structure on cell performance is relatively unknown. Numerous publications exist on individual members of this Wadsley-Roth (WR) material family, but gaps in theory and varying experimental conditions make it impossible to compare. The aim of this thesis is to provide a fair and fundamental comparison across this material class, relating compositional and structural properties to cell thermodynamics an…
author: Houck, Maurits Ernest
language: eng
keywords: activation energy, anode, Arrhenius behaviour, battery, battery materials, charge transfer kinetics, continuum model, crystallographic shear, cyclovoltammetry, density function theory, diffusion coefficient rate dependency, early transition metal oxides, electrochemical impedance spectroscopy, electrochemical parameterisation techniques, electrochemistry, energy storage, equilibrium potentials, GITT, lithium diffusion coefficient, lithium intercalation mass transfer, lithium ion battery, molecular orbital theory, Newman model, niobium oxide, parameterisation, PITT, pseudo Jahn-Teller effect, rate-limiting factor, the compensation affect, Wadsley-Roth materials, X-ray diffraction
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/55a7a3e4-aa2a-4c70-8e81-c0846139fb41/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2023-10-02
date modified: 2026-07-22T22:24:17Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.109606