Development of cathodic nanomaterials based on LiMn2O4 with Mg doping for high energy and power density lithium-ion batteries
Today, lithium–ion batteries are the dominant technology on the market for powering portable electronic devices and due to their remarkable characteristics, such as high energy and power density, low self–discharge rate, no memory effect, and long service life, are the most promising candidate for a...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2020 |
| País: | Chile |
| OAI Identifier: | oai:repositorio.anid.cl:10533/249982 |
| Acceso en línea: | https://hdl.handle.net/10533/249982 |
| Access Level: | acceso abierto |
| Palabra clave: | Ingeniería y Tecnología Ingeniería de los Materiales |
| Sumario: | Today, lithium–ion batteries are the dominant technology on the market for powering portable electronic devices and due to their remarkable characteristics, such as high energy and power density, low self–discharge rate, no memory effect, and long service life, are the most promising candidate for applications in the transportation and electrical sectors. Among the cathodic materials based on insertion oxides, LiMn2O4 spinel (LMO) is one of the most promising candidates for large format lithium–ion batteries due to its various advantages such as easy preparation, low cost, abundance of raw materials, environmentally friendly, high cell voltage and high discharge rates. However, LMO presents severe capacity fading problems during cycling, especially when the temperature is above 55 °C. The reasons for the poor electrochemical performance of LMO are dissolution of Mn through dismutación of the Mn3+ ion and destructive Jahn–Teller structural distortion. In the present work, in order to overcome the disadvantages that decrease the cycling life of the LMO, a series of Li1+xMgyMn2-x-yO4 spinels (y = 0.00, 0.02, 0.05, 0.10) was optimized by Mg doping, nano-scale particle size reduction and an octahedral morphology. Octahedral nanoparticles of Li1+xMgyMn2-x-yO4 were synthesized by means of the Pechini–type sol–gel process assisted by ultrasound and purified Mg(OH)2 from residues generated in the production of Li2CO3 using natural brines from Salar de Atacama, located in the northern Chile, was used as a doping agent. The crystallization of a pure phase of cubic spinel of space group Fd-3m took place at 500 °C and a locally ordered spinel structure was obtained at a sintering temperature of 750 °C. The characterization of the physicochemical properties showed that Mg doping was an effective strategy to improve the structural rigidity of the spinels of Li1+xMgyMn2-x-yO4 with the reduction of the cell parameter, and suppress the amount of oxygen deficiencies. The optimal composition was identified for the spinel Li1.03Mn1.92Mg0.05O4 which showed an electrochemical performance superior to C/3 with a discharge capacity of 121.3 mAh g-1 and capacity retention of 94.0% after 100 cycles at room temperature. The high exchange current density and improved Li+ ion diffusion kinetics of Li1.03Mn1.92Mg0.05O4 resulted in high-rate capability and good cycling stability at high temperatures. |
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