Hakim Iddir - Academia.edu (original) (raw)

Papers by Hakim Iddir

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Nov 17, 2020

ACS Applied Materials & Interfaces, Feb 16, 2023

Journal of The Electrochemical Society, 2016

Journal of The Electrochemical Society, 2017

Meeting abstracts, Oct 9, 2022

Increasing the capacity of cathode materials used for lithium-ion batteries is desirable, as it u... more Increasing the capacity of cathode materials used for lithium-ion batteries is desirable, as it ultimately enhances the energy density. Due to their lower cost and reversible cycling capacity of 250 – 300 mAh/g, Li- and Mn-rich LMR-NMC oxides are strong candidates as next generation cathodes used in lithium-ion batteries. Apart from the atomic structure, morphology of the cathode particles also influence their performance. LMR-NMC cathode particles are usually constructed through a two-step cathode fabrication process, which involves initial coprecipitation of the Mn-rich carbonate based cathode precursors, and later calcination of these precursors with a lithium salt at elevated temperatures. The secondary particles generally maintain their as precipitated precursor morphologies even after high temperature calcination. Even though the primary particles do change their size during calcination, the rate of oxidation and lithiation experienced by the transition metal precursors depend substantially on the primary particle morphology. Hence, it is critical to understand and control both the primary and secondary particle morphologies obtained after the coprecipitation process. In the present context, carbonate based NMC cathode precursors containing only Mn, only Ni and only Co, is precipitated, along with equal amount of the transition metals (Ni0.33Mn0.33Co0.33CO3), using conventional batch reactors. NH4HCO3 is used as the source of carbonate anions during the coprecipitation process, and the entire reaction is conducted at 50°C. The obtained particle morphologies for different transition metals are shown in Figure 1(a) as visualized using high resolution TEM techniques. Except MnCO3, all other transition metals demonstrate aggregated morphologies, which most probably form through surface growth mechanisms. Competition between growth rate and surface energies that leads to the formation of single crystalline particles for MnCO3, and particulate features for other transition metals, are demonstrated in Figure 1(b). Multiscale computational methodologies are developed to elucidate the impact of reaction kinetics and thermodynamics on determining the overall primary and secondary particle morphologies. Influence of transition metal content and ammonia concentration in determining the final particle size and size distribution will be discussed as part of this study. Figure 1

Meeting abstracts, Oct 9, 2022

Sodium-ion batteries (SIBs) has been received growing attention in the electrical energy storage ... more Sodium-ion batteries (SIBs) has been received growing attention in the electrical energy storage fields due to their low cost and earth-abundant sodium. [1] However, there has been a lack of new discoveries, growth directions, and real advancement with respect to Na-storage anodes. Despite the chemical similarities between sodium and lithium as alkali elements, the larger Na ion than Li ions (ionic radii of 0.98 Å and 0.68 Å, respectively) is limited to insertion into host materials and results in different phase transition behavior. [2] Among the available anode candidate materials for SIBs, lead (Pb), which has a large atomic size than other elements (e.g. Si, Sn), provides a big interstitial space to accommodate large Na ions by fast ionic diffusion, enabling reversible Na alloying/dealloying and exhibiting high volumetric capacity. [3] Furthermore, when Pb is used as anode with layered sodium transition metal oxide as cathode, the energy density of the pouch-type cell is estimated to be 549 Wh/L and the cost is lower than 63.5 USD/kWh according to the Argonne BatPac model. [4] Therefore, Pb-based materials have competitive potential as promising anodes and it is crucial to understand the electrochemical process from a fundamental perspective. Here, we investigate a unique Na storage mechanism using a novel Pb-based carbon nanocomposite anode synthesized by a simple high-energy milling method. The electrochemical data show a decent cycle performance with a reversible capacity of 381 mAh/g. Nevertheless, the Na-storage performance of the Pb-based anode was not attractive compared to Li cells. In-situ X-ray diffraction and ex-situ X-ray absorption spectroscopy reveal the reaction mechanism and Zintl-phase formation that limits the Na storage, unlike the Li reaction. We expect these findings provide fundamental knowledge of Na-alloying reaction and guidance for designing anode materials for high-performance SIBs. [1] K. Kubota and S. Komaba Journal of The Electrochemical Society, 2015, 162 (14) A2538-A2550 [2] M. Lao, Y. Zhang, W. Luo, Q. Yan, W. Sun, and S. X. Dou Adv. Mater. 2017, 29 , 1700622 [3] Chia-Yun Chou, Myungsuk Lee, and Gyeong S. Hwang, J. Phys. Chem. C 2015, 119, 27, 14843–14850 [4] P. Nelson, K. Gallagher, I. Bloom, Dennis Dees, and Shabbir Ahmed, BatPaC, Argonne National Laboratory. http://www.cse.anl.gov/batpac.

Journal of Physical Chemistry C, Feb 23, 2022

Journal of Physical Chemistry C, Apr 12, 2017

Layered Li(Ni 1−x−y Mn x Co y)O 2 (NMC) oxides are promising cathode materials capable of address... more Layered Li(Ni 1−x−y Mn x Co y)O 2 (NMC) oxides are promising cathode materials capable of addressing some of the challenges associated with next-generation energy storage devices. In particular, improved energy densities, longer cycle-life, and improved safety characteristics with respect to current technologies are needed. However, sufficient knowledge on the atomic-scale processes governing these metrics in working cells is still lacking. Herein, density functional theory (DFT) is employed to predict the stability of several low-index surfaces of Li(Ni 1/3 Mn 1/3 Co 1/3)O 2 (NMC111) as a function of Li and O chemical potentials. Predicted particle shapes are compared with those of single crystal NMCs synthesized under different conditions. The most stable surfaces for stoichiometric NMC111 are predicted to be the nonpolar (104), the polar (012) and (001), and the reconstructed, polar (110) surfaces. Results indicate that intermediate spin Co 3+ ions lower the (104) surface energy. Furthermore, it was found that removing oxygen from the (012) surface was easier than from the (104) surface, suggesting a facet dependence on surface-oxygen vacancy formation. These results give important insights into design criteria for the rational control of synthesis parameters as well as establish a foundation on which future mechanistic studies of NMC surface instabilities can be developed.

Meeting abstracts, Oct 9, 2022

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 25, 2018

227th ECS Meeting (May 24-28, 2015), Apr 29, 2015

NMR has been applied extensively to lithium ion battery cathode materials, of which layered-layer... more NMR has been applied extensively to lithium ion battery cathode materials, of which layered-layered composites xLi2MnO3•(1-x)LiMO2 (M=Mn,Co,Ni) are of particular interest, owing to their high energy density. In this work, NMR spectra are measured for the model layered-layered system xLi2MnO3•(1-x)LiCoO2 and Bond-Pathway-model analysis is applied to elucidate the atomic arrangement and domain structure of this material (in its pristine state, before electrochemical cycling). The simplest structural element of a domain consists of a stripe of composition LiMn2 parallel to an in-layer crystallographic axis in a metal layer of the composite. A simple model of the composite structure may be constructed by a superposition of such stripes in an LiCoO2 background. We show that such a model can account for most of the features of the observed NMR spectra. Support from the Vehicle Technologies Program U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy.

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jul 22, 2019

Cell-scale heterogeneities 2 Grain Particle Electrode thickness Electrode coating Edge effects Ce... more Cell-scale heterogeneities 2 Grain Particle Electrode thickness Electrode coating Edge effects Cell 10-15 minute fast charge of high-energy, 15-year-life electric vehicle (EV) battery

Meeting abstracts, Jun 10, 2016

LiMn2O4 (LMO) has become a promising candidate to replace LiCoO2 as a cathode material in high po... more LiMn2O4 (LMO) has become a promising candidate to replace LiCoO2 as a cathode material in high power Li-ion batteries, due to its ease of preparation, low cost and non-toxicity. However, the performance of LiMn2O4 cathode is limited by capacity fade, particularly at high temperatures. It is believed that the capacity fade of LiMn2O4 is driven by the loss of Mn resulting from the disproportionation of surface Mn3+ with the resultant divalent Mn ions dissolving into stray moisture and electrolyte. In this work, we investigate possible candidate LMO dopants that can inhibit or reduce Mn dissolution. Several dopant-selection criteria are considered, and the electronic structure of the doped LMO will be discussed.

Chemistry of Materials, Oct 23, 2020

The performance of lithium-ion batteries is intimately linked to both the structure and the morph... more The performance of lithium-ion batteries is intimately linked to both the structure and the morphology of the cathode material, which in turn is critically linked to the synthesis conditions. However, few studies focus on understanding synthesis, especially during the coprecipitation of metal oxide precursors, a process that largely determines the final morphology of the material. In this paper, we go beyond the typical equilibrium particle shape analysis conducted in the literature and incorporate kinetic aspects of morphology evolution. We perform these studies using controlled synthesis on a well-defined metal salt system (MnCO 3) combined with multiscale simulations and high-resolution microscopy. Results show that with increasing metal concentration, the particles transition from rhombohedral to cubic to spherical shapes. Computational analysis using density functional theory (DFT) reveals that rhombohedral shaped particles evolve under equilibrium conditions. Phase field techniques indicate that at higher metal concentrations, fast growth kinetics of the precipitates result in the transition to cubic and, subsequently, spherical shapes, accompanied by a decrease in particle size. This study, while limited to the one metal salt system, provides an approach to shed light on the synthesis process of mixed transition metal salts, gradient materials, and other cathode materials of interest to the battery community.

Chemistry of Materials, Jun 2, 2021

Meeting abstracts, 2016

Direct observations of local lattice aluminum environments have been a major challenge for alumin... more Direct observations of local lattice aluminum environments have been a major challenge for aluminum bearing Li-ion battery materials such as LiNi1-y-zCoyAlzO2 (NCA) and aluminum doped LiNixMnyCozO2 (NMC). 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is the only structural probe currently available that can qualitatively and quantitatively characterize lattice and non-lattice (i.e. surface, coatings, segregation, secondary phase etc.) aluminum coordination and provide information that helps discern its effect in the lattice. In the present study, we use NMR to gain new insights into transition metal (TM)-O-Al coordination and evolution of lattice aluminum sites upon cycling. With the aid of first principles DFT calculations, we show direct evidence of lattice Al sites, non-preferential Ni/Co-O-Al ordering in NCA, and the lack of bulk lattice aluminum in aluminum doped NMC. Aluminum coordination of paramagnetic (lattice) and diamagnetic (non-lattice) nature is investigated for Al-doped NMC and NCA. For the later, the evolution of the lattice site upon cycling is also studied. A clear re-ordering of lattice aluminum environments due to nickel migration is observed in NCA upon extended cycling.

Meeting abstracts, 2012

not Available.

Journal of Power Sources, Sep 1, 2020

� A model, lithium-rich cathode system having no oxygen redox is designed and studied. � Calculat... more � A model, lithium-rich cathode system having no oxygen redox is designed and studied. � Calculations and experiment reveal cation migration in the absence of oxygen redox. � Cation migration is shown to be the root cause of hysteretic behavior.

Chemistry of Materials, May 19, 2023

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Mar 24, 2020

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Nov 17, 2020

ACS Applied Materials & Interfaces, Feb 16, 2023

Journal of The Electrochemical Society, 2016

Journal of The Electrochemical Society, 2017

Meeting abstracts, Oct 9, 2022

Increasing the capacity of cathode materials used for lithium-ion batteries is desirable, as it u... more Increasing the capacity of cathode materials used for lithium-ion batteries is desirable, as it ultimately enhances the energy density. Due to their lower cost and reversible cycling capacity of 250 – 300 mAh/g, Li- and Mn-rich LMR-NMC oxides are strong candidates as next generation cathodes used in lithium-ion batteries. Apart from the atomic structure, morphology of the cathode particles also influence their performance. LMR-NMC cathode particles are usually constructed through a two-step cathode fabrication process, which involves initial coprecipitation of the Mn-rich carbonate based cathode precursors, and later calcination of these precursors with a lithium salt at elevated temperatures. The secondary particles generally maintain their as precipitated precursor morphologies even after high temperature calcination. Even though the primary particles do change their size during calcination, the rate of oxidation and lithiation experienced by the transition metal precursors depend substantially on the primary particle morphology. Hence, it is critical to understand and control both the primary and secondary particle morphologies obtained after the coprecipitation process. In the present context, carbonate based NMC cathode precursors containing only Mn, only Ni and only Co, is precipitated, along with equal amount of the transition metals (Ni0.33Mn0.33Co0.33CO3), using conventional batch reactors. NH4HCO3 is used as the source of carbonate anions during the coprecipitation process, and the entire reaction is conducted at 50°C. The obtained particle morphologies for different transition metals are shown in Figure 1(a) as visualized using high resolution TEM techniques. Except MnCO3, all other transition metals demonstrate aggregated morphologies, which most probably form through surface growth mechanisms. Competition between growth rate and surface energies that leads to the formation of single crystalline particles for MnCO3, and particulate features for other transition metals, are demonstrated in Figure 1(b). Multiscale computational methodologies are developed to elucidate the impact of reaction kinetics and thermodynamics on determining the overall primary and secondary particle morphologies. Influence of transition metal content and ammonia concentration in determining the final particle size and size distribution will be discussed as part of this study. Figure 1

Meeting abstracts, Oct 9, 2022

Sodium-ion batteries (SIBs) has been received growing attention in the electrical energy storage ... more Sodium-ion batteries (SIBs) has been received growing attention in the electrical energy storage fields due to their low cost and earth-abundant sodium. [1] However, there has been a lack of new discoveries, growth directions, and real advancement with respect to Na-storage anodes. Despite the chemical similarities between sodium and lithium as alkali elements, the larger Na ion than Li ions (ionic radii of 0.98 Å and 0.68 Å, respectively) is limited to insertion into host materials and results in different phase transition behavior. [2] Among the available anode candidate materials for SIBs, lead (Pb), which has a large atomic size than other elements (e.g. Si, Sn), provides a big interstitial space to accommodate large Na ions by fast ionic diffusion, enabling reversible Na alloying/dealloying and exhibiting high volumetric capacity. [3] Furthermore, when Pb is used as anode with layered sodium transition metal oxide as cathode, the energy density of the pouch-type cell is estimated to be 549 Wh/L and the cost is lower than 63.5 USD/kWh according to the Argonne BatPac model. [4] Therefore, Pb-based materials have competitive potential as promising anodes and it is crucial to understand the electrochemical process from a fundamental perspective. Here, we investigate a unique Na storage mechanism using a novel Pb-based carbon nanocomposite anode synthesized by a simple high-energy milling method. The electrochemical data show a decent cycle performance with a reversible capacity of 381 mAh/g. Nevertheless, the Na-storage performance of the Pb-based anode was not attractive compared to Li cells. In-situ X-ray diffraction and ex-situ X-ray absorption spectroscopy reveal the reaction mechanism and Zintl-phase formation that limits the Na storage, unlike the Li reaction. We expect these findings provide fundamental knowledge of Na-alloying reaction and guidance for designing anode materials for high-performance SIBs. [1] K. Kubota and S. Komaba Journal of The Electrochemical Society, 2015, 162 (14) A2538-A2550 [2] M. Lao, Y. Zhang, W. Luo, Q. Yan, W. Sun, and S. X. Dou Adv. Mater. 2017, 29 , 1700622 [3] Chia-Yun Chou, Myungsuk Lee, and Gyeong S. Hwang, J. Phys. Chem. C 2015, 119, 27, 14843–14850 [4] P. Nelson, K. Gallagher, I. Bloom, Dennis Dees, and Shabbir Ahmed, BatPaC, Argonne National Laboratory. http://www.cse.anl.gov/batpac.

Journal of Physical Chemistry C, Feb 23, 2022

Journal of Physical Chemistry C, Apr 12, 2017

Layered Li(Ni 1−x−y Mn x Co y)O 2 (NMC) oxides are promising cathode materials capable of address... more Layered Li(Ni 1−x−y Mn x Co y)O 2 (NMC) oxides are promising cathode materials capable of addressing some of the challenges associated with next-generation energy storage devices. In particular, improved energy densities, longer cycle-life, and improved safety characteristics with respect to current technologies are needed. However, sufficient knowledge on the atomic-scale processes governing these metrics in working cells is still lacking. Herein, density functional theory (DFT) is employed to predict the stability of several low-index surfaces of Li(Ni 1/3 Mn 1/3 Co 1/3)O 2 (NMC111) as a function of Li and O chemical potentials. Predicted particle shapes are compared with those of single crystal NMCs synthesized under different conditions. The most stable surfaces for stoichiometric NMC111 are predicted to be the nonpolar (104), the polar (012) and (001), and the reconstructed, polar (110) surfaces. Results indicate that intermediate spin Co 3+ ions lower the (104) surface energy. Furthermore, it was found that removing oxygen from the (012) surface was easier than from the (104) surface, suggesting a facet dependence on surface-oxygen vacancy formation. These results give important insights into design criteria for the rational control of synthesis parameters as well as establish a foundation on which future mechanistic studies of NMC surface instabilities can be developed.

Meeting abstracts, Oct 9, 2022

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 25, 2018

227th ECS Meeting (May 24-28, 2015), Apr 29, 2015

NMR has been applied extensively to lithium ion battery cathode materials, of which layered-layer... more NMR has been applied extensively to lithium ion battery cathode materials, of which layered-layered composites xLi2MnO3•(1-x)LiMO2 (M=Mn,Co,Ni) are of particular interest, owing to their high energy density. In this work, NMR spectra are measured for the model layered-layered system xLi2MnO3•(1-x)LiCoO2 and Bond-Pathway-model analysis is applied to elucidate the atomic arrangement and domain structure of this material (in its pristine state, before electrochemical cycling). The simplest structural element of a domain consists of a stripe of composition LiMn2 parallel to an in-layer crystallographic axis in a metal layer of the composite. A simple model of the composite structure may be constructed by a superposition of such stripes in an LiCoO2 background. We show that such a model can account for most of the features of the observed NMR spectra. Support from the Vehicle Technologies Program U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy.

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jul 22, 2019

Cell-scale heterogeneities 2 Grain Particle Electrode thickness Electrode coating Edge effects Ce... more Cell-scale heterogeneities 2 Grain Particle Electrode thickness Electrode coating Edge effects Cell 10-15 minute fast charge of high-energy, 15-year-life electric vehicle (EV) battery

Meeting abstracts, Jun 10, 2016

LiMn2O4 (LMO) has become a promising candidate to replace LiCoO2 as a cathode material in high po... more LiMn2O4 (LMO) has become a promising candidate to replace LiCoO2 as a cathode material in high power Li-ion batteries, due to its ease of preparation, low cost and non-toxicity. However, the performance of LiMn2O4 cathode is limited by capacity fade, particularly at high temperatures. It is believed that the capacity fade of LiMn2O4 is driven by the loss of Mn resulting from the disproportionation of surface Mn3+ with the resultant divalent Mn ions dissolving into stray moisture and electrolyte. In this work, we investigate possible candidate LMO dopants that can inhibit or reduce Mn dissolution. Several dopant-selection criteria are considered, and the electronic structure of the doped LMO will be discussed.

Chemistry of Materials, Oct 23, 2020

The performance of lithium-ion batteries is intimately linked to both the structure and the morph... more The performance of lithium-ion batteries is intimately linked to both the structure and the morphology of the cathode material, which in turn is critically linked to the synthesis conditions. However, few studies focus on understanding synthesis, especially during the coprecipitation of metal oxide precursors, a process that largely determines the final morphology of the material. In this paper, we go beyond the typical equilibrium particle shape analysis conducted in the literature and incorporate kinetic aspects of morphology evolution. We perform these studies using controlled synthesis on a well-defined metal salt system (MnCO 3) combined with multiscale simulations and high-resolution microscopy. Results show that with increasing metal concentration, the particles transition from rhombohedral to cubic to spherical shapes. Computational analysis using density functional theory (DFT) reveals that rhombohedral shaped particles evolve under equilibrium conditions. Phase field techniques indicate that at higher metal concentrations, fast growth kinetics of the precipitates result in the transition to cubic and, subsequently, spherical shapes, accompanied by a decrease in particle size. This study, while limited to the one metal salt system, provides an approach to shed light on the synthesis process of mixed transition metal salts, gradient materials, and other cathode materials of interest to the battery community.

Chemistry of Materials, Jun 2, 2021

Meeting abstracts, 2016

Direct observations of local lattice aluminum environments have been a major challenge for alumin... more Direct observations of local lattice aluminum environments have been a major challenge for aluminum bearing Li-ion battery materials such as LiNi1-y-zCoyAlzO2 (NCA) and aluminum doped LiNixMnyCozO2 (NMC). 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is the only structural probe currently available that can qualitatively and quantitatively characterize lattice and non-lattice (i.e. surface, coatings, segregation, secondary phase etc.) aluminum coordination and provide information that helps discern its effect in the lattice. In the present study, we use NMR to gain new insights into transition metal (TM)-O-Al coordination and evolution of lattice aluminum sites upon cycling. With the aid of first principles DFT calculations, we show direct evidence of lattice Al sites, non-preferential Ni/Co-O-Al ordering in NCA, and the lack of bulk lattice aluminum in aluminum doped NMC. Aluminum coordination of paramagnetic (lattice) and diamagnetic (non-lattice) nature is investigated for Al-doped NMC and NCA. For the later, the evolution of the lattice site upon cycling is also studied. A clear re-ordering of lattice aluminum environments due to nickel migration is observed in NCA upon extended cycling.

Meeting abstracts, 2012

not Available.

Journal of Power Sources, Sep 1, 2020

� A model, lithium-rich cathode system having no oxygen redox is designed and studied. � Calculat... more � A model, lithium-rich cathode system having no oxygen redox is designed and studied. � Calculations and experiment reveal cation migration in the absence of oxygen redox. � Cation migration is shown to be the root cause of hysteretic behavior.

Chemistry of Materials, May 19, 2023

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Mar 24, 2020