Li-Ion Battery Active Material Particle Size Control
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Solution Overview
Problem
Existing lithium ion secondary batteries face challenges in improving lithium ion input-output characteristics, particularly when using Li complex oxides with olivine, laminar rock salt, or spinel structures as positive or negative electrode active materials, which affect battery capacity and cycle performance.
Innovation Solution
The development of a lithium ion secondary battery active material that meets specific conditions, including a Li complex oxide or oxoacid salt with controlled primary particle size distribution and pore structure, optimized for improved lithium ion diffusion and conductivity, using a combination of materials like Li complex phosphates with carbon coatings to enhance electrical and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li complex oxide of olivine structure is used as positive electrode active material, then battery capacity is improved, but lithium ion storage and release speed becomes slower
Solution Approach 1:
The active material particles are divided into primary particles with controlled size distribution (D10=5-50nm, D50=50-100nm, D90=100-200nm) to reduce diffusion paths and improve lithium ion transport speed while maintaining high capacity
Solution Approach 2:
Carbon material is selectively coated on the surface of the active material particles to locally enhance electrical conductivity and facilitate lithium ion exchange at the particle surface, addressing the speed limitation without changing the bulk olivine structure
2Speed
If active material particle size is reduced to improve lithium ion diffusion, then lithium ion input-output characteristics improve, but manufacturing precision and particle size control become more difficult
Solution Approach 1:
The patent specifies precise particle size distribution parameters (D10=5-50nm, D50=50-100nm, D90=100-200nm) to optimize lithium ion diffusion while maintaining manufacturability. This quantitative parameter control balances performance improvement with manufacturing feasibility
3Power
If conductive fine particles are supported on powder surface to improve charge and discharge capacity, then electrical conductivity improves, but device complexity increases
Solution Approach 1:
The patent combines the active material and carbon coating into a single integrated structure where carbon serves multiple functions (conductivity enhancement, lithium ion exchange facilitation, particle stabilization) rather than adding separate complex components
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
This approach enhances lithium ion input-output characteristics, reducing resistance and improving charge/discharge capacity, especially under high load conditions, and prevents lithium metal deposition, leading to better battery performance and longevity.
Implementation Method 1
the storage and release of lithium ions tend to be slower when using a Li complex oxide of an olivine structure
Implementation Method 2
combining lithium transition metal complex oxide particles and carbon substance fine particles to obtain excellent input and output densities
Data Source
AI summary
A lithium ion secondary battery includes: a positive electrode; a negative electrode; and an electrolytic solution, at least one of the positive electrode and the negative electrode being capable of storing and releasing lithium ions, and containing an active material that satisfies predetermined conditions.