Lithium Tungstate Coated Cathode for Battery Output
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Solution Overview
Problem
Existing lithium-ion secondary batteries face challenges in achieving high output and capacity due to substitution of elements like Mo, W, Nb, and Re with Ni, leading to decreased battery characteristics, and existing solutions do not adequately address the issue of reducing positive-electrode resistance.
Innovation Solution
A positive-electrode material mixture comprising lithium metal composite oxide powder and lithium tungstate, with tungsten uniformly dispersed between lithium metal composite oxide particles, reduces positive-electrode resistance and improves output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If different elements such as Mo, W, Nb, Ta, or Re are added to lithium-nickel composite oxide or lithium-nickel-cobalt-manganese composite oxide to improve battery characteristics, then output characteristics and cycle characteristics are improved, but the elements substitute for Ni in the layered structure, causing battery capacity and cycle characteristics to decrease
Solution Approach 1:
The invention separates the functions of the different elements by creating a core-shell structure where the lithium-nickel composite oxide forms the core particles and the lithium tungstate forms a coating layer on the surface. This segmentation prevents the tungsten from substituting into the layered structure of the core, thereby maintaining battery capacity while still achieving improved output characteristics through the surface coating.
Solution Approach 2:
The lithium tungstate coating acts as an intermediary layer between the lithium-nickel composite oxide core and the electrolyte. This intermediate layer improves output characteristics and electrode stability without allowing direct substitution of tungsten into the nickel layered structure, thus preserving battery capacity while enhancing performance.
2Power
If high-valent transition metals such as W, Mo, Nb, Ta, or Re are added to improve output characteristics, then lower resistance is achieved, but substitution of these elements for Ni reduces battery capacity
Solution Approach 1:
The invention applies local quality by concentrating the tungsten addition specifically at the surface region (coating layer) rather than uniformly throughout the bulk material. The core particles maintain their original lithium-nickel composite oxide composition with high battery capacity, while the surface coating provides the desired low resistance and improved output characteristics.
Solution Approach 2:
The invention creates a composite material structure consisting of lithium-nickel composite oxide core particles coated with lithium tungstate. This composite structure combines the high capacity properties of the lithium-nickel composite oxide with the low resistance and improved output characteristics of the lithium tungstate coating, achieving both goals simultaneously.
3Power
If lithium tungstate is used to reduce positive-electrode resistance and improve output characteristics, then high charge-and-discharge capacity and output are achieved, but the manufacturing process must maintain uniform dispersion of tungsten between lithium metal composite oxide particles
Solution Approach 1:
The invention employs preliminary action by performing slurry preparation and uniform mixing of lithium-nickel composite oxide particles with lithium tungstate before the coating and drying processes. This preliminary uniform dispersion in liquid medium ensures that tungsten is evenly distributed on the particle surfaces before sintering, achieving the desired uniform coating without excessive complexity in the manufacturing process.
Data Source
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AI summary
Provided is a positive-electrode material for nonaqueous-electrolyte secondary batteries, the positive-electrode material being capable of achieving both high capacity and high output when used for a positive electrode for nonaqueous-electrolyte secondary batteries. Also, provided is a method for manufacturing the positive-electrode material for nonaqueous-electrolyte secondary batteries, wherein a lithium metal composite oxide powder is mixed with lithium tungstate, the lithium metal composite oxide powder being represented by a general formula Li z Ni 1-x-y Co x M y O 2 (wherein 0.10 ‰¤ x ‰¤ 0.35, 0 ‰¤ y ‰¤ 0.35, 0.97 ‰¤ z ‰¤ 1.20, and M is an addition element and at least one element selected from Mn, V, Mg, Mo, Nb, Ti, and Al) and comprising primary particles and secondary particles composed of aggregation of the primary particles.