Positive Electrode Active Material Powder for Battery Safety
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Solution Overview
Problem
Nonaqueous secondary batteries using conventional positive-electrode active material powders do not have sufficient discharge capacity while maintaining safety, particularly in preventing external and internal short-circuits.
Innovation Solution
A positive-electrode active material powder comprising a granular material capable of doping/dedoping lithium ions, with a specific surface deposit, where the percentage of particles ≤1 µm is ≤5% by volume, and an average particle diameter between 2 µm and 20 µm, formulated as Li x Ni 1-y M y O 2, with M elements like Al, Mn, Fe, Ti, Cu, and Co, and a surface deposit of elements like Al, Mn, and Co, produced through calcination and surface coating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive-electrode active material powder is used, then safety is maintained, but discharge capacity is insufficient
Solution Approach 1:
The patent changes the particle size distribution parameters, specifically controlling the percentage of fine particles (≤1 μm) to be 5% or less by volume, and setting the average particle diameter to 2-20 μm. This parameter optimization resolves the contradiction by achieving both high discharge capacity and safety without requiring fundamental material composition changes.
Solution Approach 2:
The patent creates a composite structure with a core-shell configuration where the core contains lithium compound secondary particles and the shell contains a coating element oxide. This composite structure enables simultaneous achievement of high discharge capacity (through the lithium compound core) and safety (through the protective coating shell) by combining materials with complementary properties.
2Area of stationary object
If particle size is reduced to increase surface area, then reactivity improves, but safety deteriorates due to increased fine particles
Solution Approach 1:
The patent optimizes the particle size distribution parameters by limiting fine particles (≤1 μm) to 5% or less by volume while maintaining an average particle diameter of 2-20 μm. This parameter control achieves the desired specific surface area for high reactivity while preventing safety issues associated with excessive fine particle content.
Solution Approach 2:
The patent applies different properties to different parts of the particle system: the core maintains larger particle sizes for safety and structural stability, while the surface coating provides enhanced reactivity. This local differentiation resolves the contradiction between surface area and safety by assigning different functional qualities to different regions.
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 proposed active material powder enhances discharge capacity without compromising safety, achieving higher charge and discharge capacities and improved cycle performance in nonaqueous secondary batteries.
Implementation Method 1
a granular material (A) capable of doping/dedoping lithium ions
Implementation Method 2
a deposit (B) placed on the surface of the material in a granular or layered form
Data Source
AI summary
The present invention provides a positive-electrode active material powder, which comprises a granular material (A) capable of doping/dedoping lithium ions and a deposit (B) placed on the surface of the material in a granular or layered form (herein, the material (A) and the deposit (B) are not the same), the percentage of [volumetric sum of particles having a particle diameter of 1 µm or less]/[volumetric sum of entire particles] being 5% or less.