Development of LiNi0.5Mn.1.5-xTixO4 as an Advanced Cathode for Lithium-Ion Batteries

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2018-05

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The Ohio State University

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After their successful application in small electronics, lithium-ion (Li-ion) batteries have been developed in ever larger sizes to support the energy and power requirements needed for electric vehicles (EVs). To further extend the driving distance of EVs at lower cost, there has been extensive research efforts in developing next-generation battery materials with higher energy density. LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material due to its high operating voltage of 4.7 V. However, LNMO has short cycle life issue attributed to its unwanted surficial reactions in contact with liquid electrolytes. As a solution, partial Ti substituting for Mn in LNMO was demonstrated to stabilize the particle surfaces and consequently improve the cycle life. The amount of Ti substation, however, is limited because of unexpected capacity decrease with increasing Ti content, x, in LiNi0.5Mn1.5-xTixO4. We hypothesized that such a capacity reduction is caused by a decrease in electrical conductivity; Ti4+ has no electron at its d-orbital, and increasing Ti content in LiNi0.5Mn1.5-xTixO4 reduces the charge carrier concentration. Though the research, my objective is to examine this hypothesis by experiments, and propose a strategy to improve the specific capacity of the LiNi0.5Mn1.5-xTixO4. I first synthesized LiNi0.5Mn1.0Ti0.5O4 by a sol-gel method. I reduced the particle sizes of the resulting powder, and applied carbon coating that in theory can improve the electrical conductivity between particles. I processed the resulting powders as a cathode for coin-type Li-ion battery cells, and assessed their electrochemical performance by using Arbin battery testing system. I will discuss about the effect of particle modification (e.g., size, conductive coating) on the electrochemical properties of LiNi0.5Mn1.0Ti0.5O4 as a cathode in Li-ion battery cells.

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Lithium Ion Battery, Cathode Material, Specific capacity, Electric Vehicle

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