Cathode Active Material Coating for High-Power Li-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current positive electrode active materials for nonaqueous electrolyte secondary batteries face challenges in achieving high power and capacity while maintaining excellent cycle characteristics, with issues related to resistance reduction and uniform dispersion of surface compounds like tungsten.
Innovation Solution
A positive electrode active material is developed with a specific composition of lithium, nickel, cobalt, and tungsten, where tungsten is controlled between 0.08 to 0.30 at% and primarily present as Li4WO5, forming fine particles or coating films on the surface of lithium-metal composite oxide particles to enhance lithium ion conductivity and reduce reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transition metal elements (W, Mo, Nb, Ta, Re) are added to reduce resistance, then power characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent changes the concentration parameter of tungsten from the conventional 0.01-0.05 at% to a higher range of 0.08-0.30 at%, which fundamentally alters the resistance reduction mechanism and achieves superior power characteristics without requiring complex multi-element compositions
Solution Approach 2:
The patent selects tungsten as a single additive element instead of using multiple expensive transition metals (W, Mo, Nb, Ta, Re), simplifying the manufacturing process while achieving effective resistance reduction through optimized tungsten concentration
2Use of energy by moving object
If high voltage (4-V class) is achieved using layered or spinel lithium-metal composite oxide, then energy density is improved, but resistance and power characteristics deteriorate
Solution Approach 1:
The patent applies a thin film of lithium tungstate compound on the surface of the lithium-metal composite oxide particles, which reduces interfacial resistance and improves electron conductivity, thereby enhancing power characteristics while preserving the high voltage and energy density properties
Solution Approach 2:
The patent creates a composite structure combining lithium-metal composite oxide core with lithium tungstate compound coating, where the composite material exhibits both high voltage characteristics from the core and improved conductivity from the coating layer
3Power
If surface compound concentration is increased to reduce resistance, then power characteristics are improved, but uniform dispersion becomes difficult
Solution Approach 1:
The patent optimizes the tungsten concentration parameter to 0.08-0.30 at%, which is sufficient to form a continuous protective film without excessive accumulation, ensuring uniform dispersion while achieving effective resistance reduction and improved power characteristics
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in improved battery characteristics, including high capacity, high power, and excellent cycle performance, with reduced positive electrode resistance and increased lithium ion conductivity, leading to enhanced battery performance and safety.
Implementation Method 1
forming fine particles or coating films on the surface of lithium-metal composite oxide particles to enhance lithium ion conductivity and reduce reaction resistance
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a positive electrode active material for nonaqueous electrolyte secondary batteries that allows high capacity and high power to be obtained when used as a positive electrode of nonaqueous electrolyte secondary batteries and shows excellent cycle characteristics. The positive electrode active material for nonaqueous electrolyte secondary batteries is represented by the general formula (1) : LiaNi1-x-yCOxMyWzO2+α (where 0 ≤ x ≤ 0.35, 0 ≤ y ≤ 0.35, 0.0008 ≤ z ≤ 0.030, 0.97 ≤ a ≤ 1.25, and 0 ≤ α ≤ 0.20 are satisfied, and M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti, and Al) and is constituted by a Li-metal composite oxide composed of primary particles and secondary particles formed by aggregation of the primary particles, wherein a compound including Li and W is formed on the surface of the primary particles of the Li-metal composite oxide, and wherein the amount of W contained in the compound is such that the number of atoms of W is 0.08 to 0.30 at% with respect to the total number of atoms of Ni, Co, and M contained in the positive electrode active material.