A kind of nickel-cobalt-aluminum positive electrode material coated with carbon/lithium manganese iron phosphate fiber wire and praseodymium oxide double layer and preparation method thereof

Abstract

The invention discloses a carbon / lithium manganese iron phosphate fiber wire and a nickel-cobalt-aluminum positive electrode material coated with a double layer of praseodymium oxide and a preparation method thereof. The method comprises the following steps: mixing nickel-cobalt-aluminum hydroxide with a lithium source to obtain nickel-cobalt-aluminum raw powder; uniformly dispersing praseodymium oxide and ethanol, emulsifying with the nickel-cobalt-aluminum raw powder to rheological phase, drying, Calcining to obtain nickel-cobalt-aluminum particles coated with praseodymium oxide; performing electrospinning, uniformly coating nanofibers with nano-lithium iron manganese phosphate as the inner layer and organic carbon source as the outer layer on the nickel-cobalt aluminum particles coated with praseodymium oxide Aluminum cathode material particles are calcined to obtain. The present invention uses praseodymium oxide for rheological phase coating, and then uses carbon / lithium iron manganese phosphate fiber wire for filamentous coating, which effectively reduces the residual alkali on the surface of the positive electrode material, further improves the electrical conductivity, and at the same time reduces the contact between the positive electrode material and The side reaction of the electrolyte makes the coating effect of the nickel-cobalt-aluminum positive electrode material good, and the electrical performance and cycle performance are excellent.

Description

technical field [0001] The invention belongs to the technical field of battery materials. More specifically, it relates to a carbon / lithium manganese iron phosphate fiber wire, a nickel-cobalt-aluminum positive electrode material coated with a double layer of praseodymium oxide and a preparation method thereof. Background technique [0002] In lithium-ion batteries, due to cost and technical considerations, the cathode material has always been regarded as its core part. And the high nickel ternary material (LiNi 1-x MO 2 ; M = Co, Mn, A; x ≤ 0.4) has been widely concerned and studied because of its high specific capacity and acceptable cost. Lithium nickel cobalt aluminate (LiNi 1-x-y co x Al y o 2 ; x+y≤0.2, 0<x<1, 0<y<1) positive electrode material as an example, the specific capacity of its 1C charge and discharge (voltage 3.0 ~ 4.3v) button battery can reach 185mAh / g, but it is not The stable surface chemistry and intrinsic structural instability pose...

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Problems solved by technology

In addition, in order to further reduce the side reaction between the nickel-cobalt-aluminum material and the electrolyte, some technologies often carry out double-layer or multi-layer material coating, but the above-mentioned processes have the following disadvantages: (1) there are modified materials in the dry coating The phenomenon of uneven coating and too long coating time will easily lead to uneven product batches and rapid failure of the positive electrode material coating, which will affect the stability of the coated nickel-cobalt-aluminum material. The risk of increased residual alkali on the surface of cobalt-aluminum particles; (2) Although multi-layer coating can effectively avoid the side reaction between nickel-cobalt-aluminum cathode material and electrolyte, the uniform and dense coating of multi-layer materials will easily affect the nickel-cobalt Migration of lithium ions in aluminum cathode materials, thereby reducing the electrical performance of the product

However, water is used as the coating dispersant. Since the nickel-cobalt-aluminum positive electrode material is more sensitive to moisture, in water, the nickel-cobalt-lithium aluminate material is easy to decompose lithium, resulting in the destruction of layered results, increased residual lithium, and reduced electrical properties. This damage is irreversible, and it is difficult to restore it through secondary sintering

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