Li1+xAlxTi2-x (PO3)4-coated lithium cobalt oxide material and preparation method and application thereof

Abstract

The invention discloses a Li1+xAlxTi2-x(PO4)3-coated lithium cobalt oxide material and a preparation method and application thereof. According to the preparation method, tetrabutyl titanate, triethylphosphate, lithium nitrate and aluminum nitrate are taken as raw materials to prepare a precursor solution, then the lithium cobalt oxide is dispersed in the precursor solution and the coating amountis controlled to be 0.5wt%-2wt% at high temperature of 550-750 DEG C so as to obtain the Li1+xAlxTi2-x(PO3)4-coated cobalt acid material. The lithium titanium aluminum phosphate acts as a fast ionic conductor to significantly improve the ion conduction at the positive electrode, and the performance of the battery is also good even in the 4.3-4.5V high voltage electrochemical test. Compared with the conventional positive electrode materials, the cycle stability and the rate performance are significantly improved. After 40 cycles of 0.2 C, the capacity retention of the coated positive electrodeis increased by 10% and the capacity is increased by 63 mAh / g at 2C current density.

Description

technical field [0001] The invention belongs to the field of positive electrode modification of lithium ion batteries, in particular to a Li 1+x al x Ti 2-x (PO 3 ) 4 Coated lithium cobalt oxide material and its preparation method and application. Background technique [0002] Lithium-ion batteries are widely used in many electronic devices due to their advantages of high energy density and long cycle life, and have broad prospects in energy storage. As market demand changes, higher requirements are placed on energy storage devices, and lithium-ion batteries are developing toward higher energy density and higher safety. Lithium cobalt oxide has the advantages of long cycle life, high conductivity, and large rate, and is widely used. Lithium cobalt oxide has a CoO 6 and LiO 6 The layered structure composed of regular octahedra has now developed many transition metal ion cathode materials with similar structures, such as LiNi 0.33 mn 0.33 co 0.33 o 2 and LiNi 0.6 ...

AI Technical Summary

Problems solved by technology

[0003] Currently LiCoO 2 It has been commercialized as a cathode material, but with the increase in use, the problems exposed have also increased

Lithium cobaltate positive electrode has a theoretical capacity of 274mAh / g. During the charging and discharging process, the lithium cobaltate structure changes in volume as lithium ions are repeatedly intercalated and extracted, resulting in an increase in impedance.

However, due to irreversible structural changes, its actual reversible capacity is only 145mAh / g, and a larger specific capacity can be obtained when the cut-off voltage is increased, but the cycle stability is also severely reduced.

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