Nickel-manganese-tungsten lithium ion battery positive electrode material and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion battery positive electrode materials, and particularly relates to a nickel manganese tungsten lithium ion battery positive electrode material and a preparation method thereof.The chemical formula of the nickel manganese tungsten lithium ion battery positive electrode material is LiNixMnyWzO2, and the positive electrode material is prepared through a solvothermal reaction and a high-temperature solid-phase reaction in sequence; the solvothermal reaction is that a nickel source compound, a manganese source compound and a tungsten source compound are subjected to solvothermal reaction in a water solvent containing a precipitator to prepare nickel-manganese-tungsten precursor powder; according to the high-temperature solid-phase reaction, nickel-manganese-tungsten precursor powder and a lithium source compound are subjected to ball milling and mixing, then heating sintering is conducted in the oxygen atmosphere, then heat preservation sintering is conducted, and the prepared nickel-manganese-tungsten lithium ion battery positive electrode material LiNixMnyWzO2 has excellent electrochemical activity, structural stability and safety performance.

Description

technical field [0001] The invention belongs to the technical field of positive electrode materials for lithium ion batteries, and in particular relates to a positive electrode material for nickel manganese tungsten lithium ion batteries and a preparation method thereof. Background technique [0002] Due to the increasing demand for Li-ion batteries for large-scale devices such as electric vehicles and energy storage systems, Li-ion cathode materials with high specific capacity or high operating voltage have received extensive attention as alternative cathode materials. Energy density largely determines the large-scale industrial application of electric vehicles (cruising range) or energy storage systems (calendar life), so achieving high energy density in batteries remains a challenging issue. [0003] Li-ion battery cathode materials currently used in electric vehicles are layered Li[Ni x co y (Al / Mn) 1-x-y ]O 2 (Al=NCA or Mn=NCM) oxide materials, both cathode material...

AI Technical Summary

Problems solved by technology

[0003] Li-ion battery cathode materials currently used in electric vehicles are layered Li[Ni x co y (Al / Mn) 1-x-y ]O 2 (Al=NCA or Mn=NCM) oxide materials, both cathode materials are derived from layered LiNiO 2 , which has a theoretical capacity of 270mAh / g, has been widely used and successfully commercialized due to its high capacity and low cost, but NCM and NCA cathode materials with more than 80% Ni content will promote no electrochemically active rock salt due to the increase of Ni content. Phase formation, NCM or NCA surface forms an inactive rock-salt structure NiO phase, which intensifies the migration of the nickel layer in the transition metal to the lithium layer at a high cut-off voltage, resulting in an increase in the residual alkali on the surface of the material and intensified cation mixing, causing electrode The side reaction with the electrolyte accelerates the transition to the inactive rock-salt phase and deteriorates the kinetic performance; when charging and discharging at high voltage, Ni and Co are oxidized to high valence, and then oxygen ions are oxidized, causing O 2 The release of gas and irreversible structural changes further aggravate the mechanical destruction of the crystal structure

Therefore, the inherent instability of the positive electrode directly reduces the capacity retention and thermal stability of the material, aggravates the oxygen precipitation phenomenon of the material, and causes the battery to have shortcomings such as rapid capacity decay, poor thermal stability, and decreased electrochemical performance.

[0004] Patent CN109921007A A high-nickel lithium-rich cathode material, its preparation method and application, the chemical formula of the high-nickel lithium-rich cathode material is Li 1+z (Ni 0.5+x mn 0.5-x-y m y ) 1-z o 2 or Li 1+z (Ni 0.5+x-y mn 0.5-x m y ) 1-z o 2 , the M is a VIB transition metal element, M includes Mo and / or W, preferably Mo and / or W, although the patent mentions that "because the VIB transition metal element can exhibit a higher oxidation state of positive 6 valence, especially It is molybdenum and tungsten, and can have a strong interaction with oxygen ions, and can maintain a relatively stable structure. Compared with other transition metal elements, it is easier to activate more redox pairs, contribute more capacity, and enhance structural stability. , and then endow the high-nickel-rich lithium-rich cathode material with more excellent electrochemical performance", but the high-nickel-rich lithium-rich cathode material in this patent scheme is Li 2 MnO 3 and LiM'O 2 The solid solution formed is an alloy phase in which the solute atoms dissolve into the solvent lattice and still maintain the solvent type. Materials with this structure have problems such as poor magnification and cycle performance, and voltage attenuation, especially the voltage attenuation during the cycle is serious. Moreover, the charging and discharging mechanism of lithium ions is complex, and the upper voltage limit of the material is as high as 4.8V (relying on Li 2 MnO 3 Activation contribution capacity under high voltage), the matching electrolyte must be a high-voltage electrolyte, so the universality is not high

In addition, the raw materials used in this method are nitrates, and the products produced during the preparation process will cause environmental pollution. Some complexing agents added during use are harmful to the human body, so they cannot be used in industrial production.

[0005] Therefore, in view of the above problems, the present invention proposes a positive electrode material LiNi that can be used to prepare the positive electrode of lithium ion battery x mn y W z o 2 The preparation method is to solve the problem of unsatisfactory electrochemical performance caused by cation mixing, unstable crystal structure, and poor safety performance of the battery.

Images