Lanthanum-doped lithium titanate cathode material and preparation method thereof

Abstract

The invention discloses a lanthanum-doped lithium titanate cathode material and a preparation method thereof. The molecular formula of the lanthanum-doped lithium titanate cathode material is LaxLi4-xTi5O12, wherein x is more than 0 and less than or equal to 0.1. The invention further discloses a method for preparing the lanthanum-doped lithium titanate cathode material. The method comprises the following steps of: weighing a titanium source, a lithium source and a lanthanum source, uniformly mixing, and drying; and sintering at the temperature of 550-750 DEG C for 3-5 hours, naturally cooling to room temperature, and grinding. In the preparation method provided by the invention, reactants have low prices, the melting point or decomposing temperature is low, and a low-temperature reaction is easy to undergo. The reaction temperature is low so as to contribute to controlling the appearance and size of the lanthanum-doped lithium titanate cathode material, and crystal grains can be refined by doping trace rare earth lithium, so that the electrochemical performance of lanthanum-doped lithium titanate is improved; compared with non-doped lithium titanate, the prepared lanthanum-doped lithium titanate has the advantages that: the electric conductivity is increased by two orders of magnitude; the prepared lanthanum-doped lithium titanate has superior cycle performance and rate capability without coating carbon on the surface; and the prepared lanthanum-doped lithium titanate is the lanthanum-doped lithium titanate cathode material which has superior high-temperature property and low-temperature property.

Description

Technical field [0001] The invention belongs to the technical field of inorganic non-metallic materials, and relates to a lanthanum-doped lithium titanate negative electrode material and a preparation method thereof. Background technique [0002] Spinel Li 4 Ti 5 O 12 It can maintain good structural stability during the process of lithium ion insertion and extraction, and the lattice constant basically does not change. It is a "zero strain" insertion type lithium ion battery anode material with good cycle performance; its flat voltage The plateau (1.55 V) is higher than the reduction voltage of most electrolytes and solvents, so no passivation film is formed on the electrode surface. However, the electronic and ionic conductivity of lithium titanate is very low, and the high-rate discharge performance is poor. It is often necessary to improve its electrochemical performance by means of nanometerization, doping, surface modification, etc., which is not only low in efficiency, but ...

AI Technical Summary

Problems solved by technology

At the same time, high temperature will make lithium titanate crystal grains coarse, and the shape and size are difficult to control, resulting in low electrochemical performance of lithium titanate

[0004] According to literature reports, lanthanum-doped lithium titanate can be prepared by using titanium tetrachloride as the titanium source and lanthanum chloride as the lanthanum source, but the formation of lithium chloride during the reaction will make the final product composition difficult to control, and the chloride ion in the product It needs to be removed by subsequent treatment, and the product needs to be sintered at 800°C for 16 hours. The electrochemical performance test results show that the cycle performance and rate performance of the doped lanthanum lithium titanate prepared by this method have not been improved.

[0005] In order to further improve the electrochemical performance of lithium titanate, subsequent surface carbon coating treatment is often required, which not only increases the cost and consumption, but also reduces the production efficiency.

[0006] At present, there is no research on using lithium titanate as the negative electrode material to form a full battery with lithium iron phosphate positive electrode material at home and abroad.

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