Chemistry - Journal Articles
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Item 3D printed rechargeable aqueous and non-aqueous lithium-ion batteries: Evolution of design and performance(Electrochemical Society, 2023-12-12) Egorov, Vladimir; Gulzar, Umair; O'Dwyer, Colm; Horizon 2020; European Regional Development Fund; Irish Research Council; Enterprise Ireland; Higher Education AuthorityHere we describe the modeling and design evolution of vat polimerized (Vat-P) stereolithographic apparatus (SLA) 3D printed coin cell-type aqueous and non-aqueous rechargeable lithium-ion batteries, cases and current collectors. We detail the rationale for design evolution that improved performance, handling and assembly of the printed batteries. Some guidance into the modeling, 3D printing process, material choice, chemical and electrochemical stability, assembly, sealing, and performance of 3D printed Li-ion batteries is outlined. 3D printed Li-ion batteries demonstrated promising results in terms of gravimetric capacity, rate capability, and capacity per unit footprint area compared to conventional coin cells in both aqueous and non-aqueous systems. For aqueous cells, the cell level capacity is a factor of 2–3x higher than similar metal coin cells due to the lighter weight and better rate response. We also outline design requirements for a Vat-P printed battery that are compatible with organic carbonate-based electrolytes, where the cell provides 115 mAh g−1 specific capacity using an LiCoO2–graphite chemistry, which is only ∼20% less than the maximum reversible capacity of LCO. Despite the challenges faced in optimizing the design and materials for 3D printed Li-ion batteries, this study provides valuable information for future research and development.Item Asymmetrical optical response of opal photonic crystals with graded thickness(IOP Publishing, 2023-11-27) Grant, Alex; O'Dwyer, Colm; Irish Research CouncilThe influence of thickness gradient and structural order on the spectral response of opal photonic crystals (PhCs) grown by evaporation-induced self-assembly (EISA) are presented. SEM imaging and angle resolved optical transmission spectroscopy are used to investigate the evolution of the PBG along a thickness gradient for opals grown from five different colloidal sphere concentrations at two different evaporation rates. The degradation of structural order along the thickness gradient is demonstrated, the occurrence of which attenuates the PBG with the thinning of the opal film and results in asymmetrical angle-resolved transmission spectra. The asymmetry in transmission intensity becomes more pronounced for opals grown from lower volume fractions, where secondary Bragg reflections also appear at low incident angles.Item Operando color-coding of reversible lithiation and cycle life in batteries using photonic crystal materials(IOP Publishing, 2023-12-27) Lonergan, Alex; Gulzar, Umair; Zhang, Yan; O'Dwyer, Colm; Horizon 2020; Irish Research CouncilInnovative new materials are consistently emerging as electrode candidates from lithium-ion and emerging alternative battery research, promising high energy densities and high-rate capabilities. Understanding potential structural changes, morphology evolution, degradation mechanisms and side reactions during lithiation is important for designing, optimizing and assessing aspiring electrode materials. In-situ and operando analysis techniques provide a means to investigate these material properties under realistic operating conditions. Here, we demonstrate operando spectroscopic sensing using photonic crystal-structured electrodes that uses the optical transmission spectrum to monitor changes to the state of charge or discharge during lithiation, and the change to electrode structure, in real-time. Photonic crystals possess a signature optical response, with a photonic bandgap (or stopband) presenting as a structural color reflection from the material. We leverage the presence of this photonic stopband, alongside its intricate relationship to the electrode structure and material phase, to correlate electrode lithiation with changes to the optical spectrum during operation. We explore the optical and electrochemical behavior of a TiO2 anode in a lithium-ion battery, structured as a photonic crystal. The operando optical sensing demonstrated here is versatile and applicable to a wide range of electrochemical electrode material candidates when structured with ordered porosity akin to a photonic crystal structure.Item Three-dimensionally ordered macroporous amorphous C/TiO2 composite electrodes for lithium-ion batteries(IOP Publishing, 2024-02-09) Carroll, Aoife; Grant, Alex; Zhang, Yan; Gulzar, Umair; Ahad, Syed Abdul; Geaney, Hugh; O’Dwyer, Colm; Science Foundation Ireland; Irish Research Council; Horizon 2020A facile method utilizing colloidal templating and sucrose as a carbon precursor is used to synthesize highly ordered, porous inverse opal structures as C/TiO2 nanocomposites. Material characterization shows amorphous TiO2 and a large pore size of ∼400 nm allowing for enhanced electrolyte penetration. C/TiO2 inverse opals materials as electrodes in Li-ion battery half cells demonstrate discharge and charge capacities of ∼870 mAh g−1 and 470 mAh g−1, respectively, at a current density of 150 mA g−1. The enhanced capacities, which surpass theoretical limits for TiO2 and carbon based on intercalation reactions, are analyzed under voltammetric conditions to assess relative contributions to capacity from diffusion-limited intercalation and capacitive charge compensation reactions. The porous structure contributes to excellent capacity retention, rate performance and improved Coulombic efficiency (99.6% after 250 cycles), compared to individual carbon and TiO2 inverse opals.Item Carbon inverse opal macroporous monolithic structures as electrodes for Na-ion and K-ion batteries(IOP Publishing, 2024-03-27) Carroll, Aoife; Grant, Alex; Zhang, Yan; Gulzar, Umair; Ahad, Syed Abdul; Geaney, Hugh; O'Dwyer, Colm; European Regional Development Fund; Irish Research Council; Horizon 2020; Science Foundation IrelandHighly ordered three-dimensionally structured carbon inverse opals (IOs) produced from sucrose are stable electrodes in sodium-ion and potassium-ion batteries. The walls of the ordered porous carbon structure contain short-range graphitic areas. The interconnected open-worked structure defines a conductive macroporous monolithic electrode that is easily wetted by electrolytes for Na-ion and K-ion systems. Electrochemical characterization in half-cells against Na metal electrodes reveals stable discharge capacities of 25 mAh g−1 at 35 mA g−1 and 40 mAh g−1 at 75 mA g−1 and 185 mA g−1. In K-ion half cells, the carbon IO delivers capacities of 32 mAh g−1 at 35 mA g−1 and ∼25 mAh g−1 at 75 mA g−1 and 185 mA g−1. The IOs demonstrate storage mechanisms involving both capacitive and diffusion-controlled processes. Comparison with non-templated carbon thin films highlights the superior capacity retention (72% for IO vs 58% for thin film) and cycling stability of the IO structure in Na-ion cells. Robust structural integrity against volume changes with larger ionic radius of potassium ions is maintained after 250 cycles in K-ion cells. The carbon IOs exhibit stable coulombic efficiency (>99%) in sodium-ion batteries and better coulombic efficiency during cycling compared to typical graphitic carbons.