Santander M Nieto - Academia.edu (original) (raw)
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Papers by Santander M Nieto
Advances in Materials Science and Engineering, 2014
Prospective cathode materialsLiNi0.7–xMgxCo0.3O2(0≤x≤0.1) for a lithium-ion secondary battery wer... more Prospective cathode materialsLiNi0.7–xMgxCo0.3O2(0≤x≤0.1) for a lithium-ion secondary battery were synthesized using a sol-gel method. The structural and electrochemical properties were examined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry(CV), and charge-discharge tests. The results show that theLiNi0.7–xMgxCo0.3O2maintains theα-NaFeO2type layered structure regardless of the magnesium content in the rangex⩽0.1. On the other hand, Mg-doping improves the capacity retention well. Besides, the Mg-doping promotes the diffusion of Li+in LiNi0.7Co0.3O2. Moreover, Mg-doping suppresses the phase transitions that usually occur in LiNiO2during cycling and improves the charge-discharge reversibility of Li/LiNi0.7Co0.3O2. High temperature cycling performance of the cathode at 55.5°C is also improved by Mg-doping, which is possibly attributed to the total stronger metal-oxygen bonding and the enhanced structure stability of those delithiated Mg-dope...
Lithium intercalation materials are of special interest for cathodes in rechargeable lihium-ion b... more Lithium intercalation materials are of special interest for cathodes in rechargeable lihium-ion batteries, because they are capable of reversibly intercalating lithium ions without altering the main unit. We developed a novel solution-based route for the synthesis of these lithium intercalates oxides. The first part of this work was devoted to the optimization of chemical solution process parameters in order to correlate their electrochemical properties. It was found that the lattice parameters and the crystallite size increase, whereas the lattice strain decreases with the increase in calcinations temperature. Powders annealed at 700°C for 15 h yielded best electrochemical performance. The electrochemical performance of substituted Li1.2Mn2O 4, Li1.2Mn1.8O4, Li1.2Cr 0.05Mn1.95O4, and Li1.2Cr0.05 Mn1.75O4 spinel electrodes in lithium cell has been studied. The electrochemical data showed that the Li and Cr dopant effect improves the cycleablility of spinel LiMn2O4 electrodes. The second part of this dissertation was devoted to improve the rate capabilities of these cathode materials by growing nano-size cathode particles and also by cation co-doping. Though the discharge capacity of these nano-crystalline cathodes was equivalent to their microcrystalline counterpart, these exhibited capacity fading in the 4V range. Through a combined X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses, we correlated the observed capacity fading with the onset of Jahn-Teller (J-T) distortion toward the end of the discharge in the cut-off limit between 4.2 and 3.2V. It was postulated that J-T distortion is the dominant fading mechanism of these nano-crystalline cathodes then by increasing the average oxidation state of the Mn ion in a virgin lithium manganate cathode, the onset of such distortion towards the end of the discharge could be delayed, and therefore, the cycleability of these cathodes could be improved. By synthesizing lithium and aluminum ion co-doped lithium manganate particles, we could increase the average oxidation state of Mn ions in the virgin electrodes. Indeed, the cycleability of these co-doped cathodes was dramatically improved which supports our population. The third part of this thesis was devoted to synthesis and electrochemical properties of layered compounds. Lithium nickel oxides derivatives are promising positive materials for the next generation of lithium-ion batteries. Partial substitution of certain cations for nickel in this family of oxides which satisfies the demanding requirements for rechargeable battery applications. In this part the interest is focused on the effect of simultaneous cobalt as well as aluminum doping was studied to understand their effect on the phase formation behavior and electrochemical properties of solution derived lithium nickel oxide cathode materials for rechargeable batteries. (Abstract shortened by UMI.)
Journal of Physical Chemistry C, 2007
Powders of BaCe0.95Yb0.05O3-‰ were synthesized using the standard solid-state reaction method. Th... more Powders of BaCe0.95Yb0.05O3-‰ were synthesized using the standard solid-state reaction method. The produced materials were characterized by XRD, SEM, and Raman spectrometry. The absorption kinetics of hydrogen was studied using the TA-TQ500 TGA. The XRD study established the following: the phase composition, cell parameters, and crystallite size. The SEM investigation allowed us to confirm the crystallite size. The Raman study permitted us to confirm the sample phase composition. The absorption study revealed higher absorption magnitudes than those possible if we consider that the proton can only be located in the oxide anions of the perovskite. To explain these results, we proposed that at high temperature the proton could be interstitially located in tetrahedral and octahedral sites because of the increment with temperature of electrons in the conduction band during hydrogen absorption. The enthalpy of absorption, ¢Hab 0 , was measured, and it was found that ¢H ab 0 ) 3.6 eV, a positive value in agreement with the increase with temperature of electrons in the conduction band. Besides, the chemical and self-diffusion coefficients were computed. Subsequently, were calculated the activation energy, Ea, and the pre-exponential factor, D 0 / , using the self-diffusion data. The values obtained were Ea ) 1.6 eV and D0 / ) 0.5 10 -9 m 2 /s.
Journal of Power Sources, 2007
As a cathode material for lithium ion rechargeable batteries, LiNi0.8Co0.2O2 (LNCO) is one of the... more As a cathode material for lithium ion rechargeable batteries, LiNi0.8Co0.2O2 (LNCO) is one of the most attractive candidates for high power electronic devices. In the present work, we have synthesized LNCO powder by solid-state route. The discharge capacity and the capacity retention of LNCO cathode are found to be ∼100 mAh g−1 and ∼63%, respectively. Molybdenum doping, replacing parts of cobalt ion in LNCO lattice increases the discharge capacity (∼157 mAh g−1) and improve its capacity retention characteristics. Through X-ray Rietveld analyses, we have found that Mo doping increases the inter-slab spacing between the (Co,Ni)O2 octahedral layers which provides easier Li1+ intercalation leading to improved electrochemical properties in the modified cathode.
Journal of Power Sources, 2008
Li(Ni0.8Co0.1Mn0.1)O2 cathode materials were synthesized by solid-state reaction route. Single-ph... more Li(Ni0.8Co0.1Mn0.1)O2 cathode materials were synthesized by solid-state reaction route. Single-phase layer structure with hexagonal unit cell having R3¯m symmetry was obtained and the average particle size was around 6 μm. Electrochemical studies showed single redox reaction and a maximum charging capacity of ∼140 mAh g−1 was obtained. Ex situ structural studies by X-ray diffraction and Raman scattering at various stages of charging and discharging showed that the host layered structure is maintained throughout the electrochemical lithiation–delithiation processes in the 3–4.5 V range with systematic change in the lattice parameters. First discharge capacity was 132 mAh g−1 and the capacity retention was ∼86% after 20 charge–discharge cycles.
Journal of Power Sources, 2004
Lithium manganate spinel is extensively studied as a positive electrode in lithium ion rechargeab... more Lithium manganate spinel is extensively studied as a positive electrode in lithium ion rechargeable batteries. Growth of nano-size cathode particles is proposed to improve the rate capabilities of these cathode materials. It remains controversial if the particle size in the nano-range (as compared to the conventional micrometer size particles of these materials) has any appreciable influence on the discharge capacity, rate capabilities, and cycleability of these materials. In the 4 V range, especially at slightly elevated temperature, lithium manganate exhibits capacity fading though the underlying mechanism for such fading is not yet clear. In the present work, we have successfully prepared nano-crystalline lithium manganate spinel powder by an acetate base solution route. Though the discharge capacity of these nano-crystalline cathodes was equivalent to their microcrystalline counterpart, these exhibited capacity fading in the 4 V range. Through a combined X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses, we correlated the observed capacity fading with the onset of Jahn–Teller (J–T) distortion toward the end of the discharge in the cut-off limit between 4.2 and 3.4 V. It was postulated that if J–T distortion is the dominant fading mechanism of these nano-crystalline cathodes then by increasing the average oxidation state of the Mn ions in a virgin lithium manganate cathode, the onset of such distortion towards the end of the discharge could be delayed, and therefore, the cycleability of these cathodes could be improved. By synthesizing lithium and aluminum ion co-doped lithium manganate particles, we could increase the average oxidation state of the Mn ions in the virgin electrodes. Indeed, the cycleability of these co-doped cathodes was dramatically improved which supports our postulation. The doping contents of lithium and aluminum, however, should be further optimized to further increase the discharge capacity of these modified cathodes.
Journal of Power Sources, 2006
The effect of simultaneous cobalt as well as aluminum doping was studied to understand their effe... more The effect of simultaneous cobalt as well as aluminum doping was studied to understand their effect on the phase formation behavior and electrochemical properties of solution derived lithium nickel oxide cathode materials for rechargeable batteries. The discharge capacities of LiNi0.80Co0.20O2 and LiNi0.80Co0.15Al0.05O2 cathodes, measured at constant current densities of 0.45 mA cm−2 in the cut-off voltage range of 4.3–3.2 V, were 100 and 136 mAh g−1, respectively. LiNi0.80Co0.15Al0.05O2 had better cycleability than the LiNi0.80Co0.20O2 cathodes. The retention of undesirable Li2CO3 phase both in LiNi0.80Co0.20O2 and LiNi0.80Co0.15Al0.05O2 cathodes was argued to be responsible for the relatively lower discharge capacity of these materials.
Journal of Power Sources, 2007
Spinel powders of LiMn1.99Nd0.01O4 have been synthesized by chemical synthesis route to prepare c... more Spinel powders of LiMn1.99Nd0.01O4 have been synthesized by chemical synthesis route to prepare cathodes for Li-ion coin cells. The structural and electrochemical properties of these cathodes were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry, and charge-discharge studies. The cyclic voltammetry of the cathodes revealed the reversible nature of Li-ion intercalation and deintercalation in the electrochemical cell. The charge-discharge characteristics for LiMn1.99Nd0.01O4 cathode materials were obtained in 3.4–4.3 V voltage range and the initial discharge capacity of this material were found to be about 149 mAh g−1. The coin cells were tested for up to 25 charge-discharge cycles. The results show that by doping with small concentration of rare-earth element Nd, the capacity fading is considerably reduced as compared to the pure LiMn2O4 cathodes, making it suitable for Li-ion battery applications.
Advances in Materials Science and Engineering, 2014
Prospective cathode materialsLiNi0.7–xMgxCo0.3O2(0≤x≤0.1) for a lithium-ion secondary battery wer... more Prospective cathode materialsLiNi0.7–xMgxCo0.3O2(0≤x≤0.1) for a lithium-ion secondary battery were synthesized using a sol-gel method. The structural and electrochemical properties were examined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry(CV), and charge-discharge tests. The results show that theLiNi0.7–xMgxCo0.3O2maintains theα-NaFeO2type layered structure regardless of the magnesium content in the rangex⩽0.1. On the other hand, Mg-doping improves the capacity retention well. Besides, the Mg-doping promotes the diffusion of Li+in LiNi0.7Co0.3O2. Moreover, Mg-doping suppresses the phase transitions that usually occur in LiNiO2during cycling and improves the charge-discharge reversibility of Li/LiNi0.7Co0.3O2. High temperature cycling performance of the cathode at 55.5°C is also improved by Mg-doping, which is possibly attributed to the total stronger metal-oxygen bonding and the enhanced structure stability of those delithiated Mg-dope...
Lithium intercalation materials are of special interest for cathodes in rechargeable lihium-ion b... more Lithium intercalation materials are of special interest for cathodes in rechargeable lihium-ion batteries, because they are capable of reversibly intercalating lithium ions without altering the main unit. We developed a novel solution-based route for the synthesis of these lithium intercalates oxides. The first part of this work was devoted to the optimization of chemical solution process parameters in order to correlate their electrochemical properties. It was found that the lattice parameters and the crystallite size increase, whereas the lattice strain decreases with the increase in calcinations temperature. Powders annealed at 700°C for 15 h yielded best electrochemical performance. The electrochemical performance of substituted Li1.2Mn2O 4, Li1.2Mn1.8O4, Li1.2Cr 0.05Mn1.95O4, and Li1.2Cr0.05 Mn1.75O4 spinel electrodes in lithium cell has been studied. The electrochemical data showed that the Li and Cr dopant effect improves the cycleablility of spinel LiMn2O4 electrodes. The second part of this dissertation was devoted to improve the rate capabilities of these cathode materials by growing nano-size cathode particles and also by cation co-doping. Though the discharge capacity of these nano-crystalline cathodes was equivalent to their microcrystalline counterpart, these exhibited capacity fading in the 4V range. Through a combined X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses, we correlated the observed capacity fading with the onset of Jahn-Teller (J-T) distortion toward the end of the discharge in the cut-off limit between 4.2 and 3.2V. It was postulated that J-T distortion is the dominant fading mechanism of these nano-crystalline cathodes then by increasing the average oxidation state of the Mn ion in a virgin lithium manganate cathode, the onset of such distortion towards the end of the discharge could be delayed, and therefore, the cycleability of these cathodes could be improved. By synthesizing lithium and aluminum ion co-doped lithium manganate particles, we could increase the average oxidation state of Mn ions in the virgin electrodes. Indeed, the cycleability of these co-doped cathodes was dramatically improved which supports our population. The third part of this thesis was devoted to synthesis and electrochemical properties of layered compounds. Lithium nickel oxides derivatives are promising positive materials for the next generation of lithium-ion batteries. Partial substitution of certain cations for nickel in this family of oxides which satisfies the demanding requirements for rechargeable battery applications. In this part the interest is focused on the effect of simultaneous cobalt as well as aluminum doping was studied to understand their effect on the phase formation behavior and electrochemical properties of solution derived lithium nickel oxide cathode materials for rechargeable batteries. (Abstract shortened by UMI.)
Journal of Physical Chemistry C, 2007
Powders of BaCe0.95Yb0.05O3-‰ were synthesized using the standard solid-state reaction method. Th... more Powders of BaCe0.95Yb0.05O3-‰ were synthesized using the standard solid-state reaction method. The produced materials were characterized by XRD, SEM, and Raman spectrometry. The absorption kinetics of hydrogen was studied using the TA-TQ500 TGA. The XRD study established the following: the phase composition, cell parameters, and crystallite size. The SEM investigation allowed us to confirm the crystallite size. The Raman study permitted us to confirm the sample phase composition. The absorption study revealed higher absorption magnitudes than those possible if we consider that the proton can only be located in the oxide anions of the perovskite. To explain these results, we proposed that at high temperature the proton could be interstitially located in tetrahedral and octahedral sites because of the increment with temperature of electrons in the conduction band during hydrogen absorption. The enthalpy of absorption, ¢Hab 0 , was measured, and it was found that ¢H ab 0 ) 3.6 eV, a positive value in agreement with the increase with temperature of electrons in the conduction band. Besides, the chemical and self-diffusion coefficients were computed. Subsequently, were calculated the activation energy, Ea, and the pre-exponential factor, D 0 / , using the self-diffusion data. The values obtained were Ea ) 1.6 eV and D0 / ) 0.5 10 -9 m 2 /s.
Journal of Power Sources, 2007
As a cathode material for lithium ion rechargeable batteries, LiNi0.8Co0.2O2 (LNCO) is one of the... more As a cathode material for lithium ion rechargeable batteries, LiNi0.8Co0.2O2 (LNCO) is one of the most attractive candidates for high power electronic devices. In the present work, we have synthesized LNCO powder by solid-state route. The discharge capacity and the capacity retention of LNCO cathode are found to be ∼100 mAh g−1 and ∼63%, respectively. Molybdenum doping, replacing parts of cobalt ion in LNCO lattice increases the discharge capacity (∼157 mAh g−1) and improve its capacity retention characteristics. Through X-ray Rietveld analyses, we have found that Mo doping increases the inter-slab spacing between the (Co,Ni)O2 octahedral layers which provides easier Li1+ intercalation leading to improved electrochemical properties in the modified cathode.
Journal of Power Sources, 2008
Li(Ni0.8Co0.1Mn0.1)O2 cathode materials were synthesized by solid-state reaction route. Single-ph... more Li(Ni0.8Co0.1Mn0.1)O2 cathode materials were synthesized by solid-state reaction route. Single-phase layer structure with hexagonal unit cell having R3¯m symmetry was obtained and the average particle size was around 6 μm. Electrochemical studies showed single redox reaction and a maximum charging capacity of ∼140 mAh g−1 was obtained. Ex situ structural studies by X-ray diffraction and Raman scattering at various stages of charging and discharging showed that the host layered structure is maintained throughout the electrochemical lithiation–delithiation processes in the 3–4.5 V range with systematic change in the lattice parameters. First discharge capacity was 132 mAh g−1 and the capacity retention was ∼86% after 20 charge–discharge cycles.
Journal of Power Sources, 2004
Lithium manganate spinel is extensively studied as a positive electrode in lithium ion rechargeab... more Lithium manganate spinel is extensively studied as a positive electrode in lithium ion rechargeable batteries. Growth of nano-size cathode particles is proposed to improve the rate capabilities of these cathode materials. It remains controversial if the particle size in the nano-range (as compared to the conventional micrometer size particles of these materials) has any appreciable influence on the discharge capacity, rate capabilities, and cycleability of these materials. In the 4 V range, especially at slightly elevated temperature, lithium manganate exhibits capacity fading though the underlying mechanism for such fading is not yet clear. In the present work, we have successfully prepared nano-crystalline lithium manganate spinel powder by an acetate base solution route. Though the discharge capacity of these nano-crystalline cathodes was equivalent to their microcrystalline counterpart, these exhibited capacity fading in the 4 V range. Through a combined X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses, we correlated the observed capacity fading with the onset of Jahn–Teller (J–T) distortion toward the end of the discharge in the cut-off limit between 4.2 and 3.4 V. It was postulated that if J–T distortion is the dominant fading mechanism of these nano-crystalline cathodes then by increasing the average oxidation state of the Mn ions in a virgin lithium manganate cathode, the onset of such distortion towards the end of the discharge could be delayed, and therefore, the cycleability of these cathodes could be improved. By synthesizing lithium and aluminum ion co-doped lithium manganate particles, we could increase the average oxidation state of the Mn ions in the virgin electrodes. Indeed, the cycleability of these co-doped cathodes was dramatically improved which supports our postulation. The doping contents of lithium and aluminum, however, should be further optimized to further increase the discharge capacity of these modified cathodes.
Journal of Power Sources, 2006
The effect of simultaneous cobalt as well as aluminum doping was studied to understand their effe... more The effect of simultaneous cobalt as well as aluminum doping was studied to understand their effect on the phase formation behavior and electrochemical properties of solution derived lithium nickel oxide cathode materials for rechargeable batteries. The discharge capacities of LiNi0.80Co0.20O2 and LiNi0.80Co0.15Al0.05O2 cathodes, measured at constant current densities of 0.45 mA cm−2 in the cut-off voltage range of 4.3–3.2 V, were 100 and 136 mAh g−1, respectively. LiNi0.80Co0.15Al0.05O2 had better cycleability than the LiNi0.80Co0.20O2 cathodes. The retention of undesirable Li2CO3 phase both in LiNi0.80Co0.20O2 and LiNi0.80Co0.15Al0.05O2 cathodes was argued to be responsible for the relatively lower discharge capacity of these materials.
Journal of Power Sources, 2007
Spinel powders of LiMn1.99Nd0.01O4 have been synthesized by chemical synthesis route to prepare c... more Spinel powders of LiMn1.99Nd0.01O4 have been synthesized by chemical synthesis route to prepare cathodes for Li-ion coin cells. The structural and electrochemical properties of these cathodes were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry, and charge-discharge studies. The cyclic voltammetry of the cathodes revealed the reversible nature of Li-ion intercalation and deintercalation in the electrochemical cell. The charge-discharge characteristics for LiMn1.99Nd0.01O4 cathode materials were obtained in 3.4–4.3 V voltage range and the initial discharge capacity of this material were found to be about 149 mAh g−1. The coin cells were tested for up to 25 charge-discharge cycles. The results show that by doping with small concentration of rare-earth element Nd, the capacity fading is considerably reduced as compared to the pure LiMn2O4 cathodes, making it suitable for Li-ion battery applications.