Synthesis of modified lithium-rich layered positive electrode material doped with anions of F<->, Cl<-> and Br<->

Abstract

The invention relates to a doping modified lithium-rich layered positive electrode material and a preparation method thereof, in particular to a new novel lithium-rich layered positive electrode through doping modification on a material by anions of F<->, Cl<-> and Br<-> according to a certain proportion, and belongs to the technical field of a lithium ion battery. The synthesis method comprises the following steps of firstly, weighing a lithium salt, a metal nitrate and a non-metal salt according to mole ratios, dissolving the lithium salt, the metal nitrate and the non-metal salt in deionized water, adding citric acid, and adjusting a pH value to be 7-8 with ammonia; secondly, heating, stirring and reacting the obtained mixture to obtain wet gel, drying the wet gel to obtain dry gel, and pre-sintering the dry gel to obtain a precursor; and finally, carrying out high-temperature roasting and grinding to obtain the lithium-rich positive electrode Li[Li<0.2>Ni<0.15>Mn<0.55>Co<0.1>]O<2-x>M<x> (M is F, Cl or Br) (0<=x<0.1), namely the modified layered lithium-rich positive electrode material. The positive electrode material prepared according to the method is small and uniform in particle, smooth in surface and high crystallization property, and thus, the positive electrode material has relatively high discharge specific capacitance and favorable rate performance; and by co-doping, the cycle performance and the initial coulombic efficiency of the positive electrode material can be improved, the irreversible capacitance loss is reduced, and thus, the positive electrode material has great industrial significance.

Description

technical field [0001] The invention relates to an anion-doped modified layered lithium-rich cathode material and a preparation method thereof, belonging to the technical field of lithium-ion batteries. Background technique [0002] In today's world, with the rapid development of science and technology, lithium secondary batteries occupy an important position in portable electronic products, medical equipment and other fields because of their advantages such as environmental protection, high specific capacity, and "no memory effect". The composition of lithium-rich cathode materials is complex, xLi 2 MnO 3 ·(1-x)LiMO 2 The combination of M in the structure is changeable. Looking at this structure, it has α-NaFeO 2 A layered configuration in which Na is replaced by Li and Fe is replaced by Li and a class of transition metal ions (e.g., nickel, manganese, cobalt). Belongs to the hexagonal crystal system, R-3m space group, Li occupies the 3a position, transition metal occup...

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Problems solved by technology

[0004] Although lithium-rich cathode materials have the above advantages, their rate performance and first Coulombic efficiency are still relatively low, which is the bottleneck restricting their development.

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