Al/La co-doped high-nickel ternary precursor with core-shell structure and preparation method thereof, and positive electrode material

Abstract

The invention relates to the field of lithium ion battery materials, and provides an Al / La co-doped high-nickel ternary precursor with a core-shell structure and a preparation method thereof, and a positive electrode material prepared from the precursor. The preparation method mainly comprises the following three steps: step 1, synthesizing an Al-doped high-nickel ternary precursor with rod-like primary particles under the condition of a low pH value; 2, increasing the pH value on the basis of the step 1, growing a La-doped high-nickel ternary precursor shell with needle-shaped primary particles by taking the Al-doped high-nickel ternary precursor as an inner core so as to synthesize an Al / La co-doped high-nickel ternary precursor with a core-shell structure; and 3, mixing the Al / La co-doped high-nickel ternary precursor with the core-shell structure and a lithium salt, and carrying out high-temperature calcination in an oxygen atmosphere to obtain the Al / La co-doped ternary positive electrode material with the core-shell structure. Due to the unique co-doped core-shell structure, the stability of an internal structure is effectively enhanced, the generation of mixed phases such ascation mixing and rock salt structures is inhibited, the breakage of grain boundaries is reduced, the average oxidation state of manganese ions is improved, the Jahn-Teller effect is effectively inhibited, the rapid attenuation of the capacity in a cycle process is reduced, the cycle stability of the material is remarkably improved, and the cycle life of the material is remarkably prolonged. Theproduct synthesized by adopting a coprecipitation method is uniform in component, good in sphericity, good in reproducibility, easy in condition control, low in preparation cost, high in economic value and wide in application prospect.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a core-shell structure Al / La co-doped high-nickel ternary precursor and a preparation method thereof, and a core-shell structure Al / La co-doped high-nickel ternary positive electrode Material. Background technique [0002] Lithium-ion batteries (LiBs) play an important role in clean energy due to their low cost, high energy density, and long lifetime. The cathode materials for the new generation of lithium-ion batteries require higher energy density, longer cycle life, and better safety for electric vehicles and energy storage. Nickel-rich (Ni content>60%) cathode material LiNi x co y mn 1-x-y o 2 (NCM) and LiNi x co y al 1-x-y o 2 (NCA) can basically meet the requirements. However, nickel-rich materials face defects such as degradation of material structure and poor thermal stability under high voltage and high temperature. This is due to the low cont...

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Problems solved by technology

Using CO 3 2- To improve the crystallization of the precipitant, although the oxidation problem of Mn is avoided, the electrochemical performance of the material cannot be fundamentally improved by simply improving the precipitant.

Meanwhile, in Li + The problem that the transmission channel is blocked by the gap between the core and the shell during the deintercalation process is also not solved

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