LFP Positive Electrode Coating for Adhesion and Heat Resistance
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Solution Overview
Problem
Positive electrode active materials with an olivine crystal structure, such as lithium iron phosphate, exhibit low lithium ion diffusibility and electronic conductivity, leading to insufficient battery characteristics, and there is a lack of study on adhesion between the current collector and the positive electrode active material layer in non-aqueous electrolyte secondary batteries.
Innovation Solution
A positive electrode design with a current collector coated by a conductive material and a positive electrode active material layer containing lithium iron phosphate particles coated with conductive carbon, achieving high adhesion and resistance to high-temperature deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium iron phosphate with an olivine crystal structure is used as the positive electrode active material, then safety is improved due to strong covalent bonds preventing oxygen release, but lithium ion diffusibility and electronic conductivity deteriorate leading to insufficient battery characteristics
Solution Approach 1:
The patent uses a composite structure where lithium iron phosphate particles are coated with conductive carbon material. This composite approach combines the safety benefits of olivine-structured lithium iron phosphate with the electrical conductivity advantages of carbon coating, thereby improving overall battery characteristics while maintaining safety
Solution Approach 2:
The patent modifies the surface properties of lithium iron phosphate particles by coating them with conductive carbon, changing the electrical conductivity parameter at the particle surface without altering the bulk olivine crystal structure, thus improving electronic conductivity while preserving safety
2Reliability
If the adhesion between the current collector and the positive electrode active material layer is improved, then battery characteristics are enhanced, but there is a lack of understanding and control methods for this adhesion in olivine structure batteries
Solution Approach 1:
The patent introduces a conductive carbon coating as an intermediary layer between the lithium iron phosphate particles and the current collector. This intermediary layer improves adhesion and provides a mechanism for understanding and controlling the interface between the active material and current collector
Solution Approach 2:
The patent changes the surface parameters of the active material particles through carbon coating, which affects adhesion properties and provides a controllable parameter for optimizing battery characteristics
3Duration of action of stationary object
If resistance to high-temperature deterioration is improved, then battery durability is enhanced, but conventional methods do not provide sufficient resistance for olivine structure materials
Solution Approach 1:
The conductive carbon coating forms a protective composite structure around the lithium iron phosphate particles, providing thermal stability and resistance to high-temperature deterioration, thereby enhancing battery durability
Solution Approach 2:
The carbon coating is applied beforehand to protect the lithium iron phosphate particles from high-temperature degradation during battery operation, cushioning against thermal stress and chemical degradation
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 design enhances the adhesion between the current collector and the positive electrode active material layer, improving battery characteristics and resistance to high-temperature degradation.
Implementation Method 1
the adhesion between the current collector and the positive electrode active material layer affects the battery characteristics
Implementation Method 2
the current collector has, on at least a part of its surface on a side of the positive electrode active material layer, a current collector coating layer including a conductive material
Data Source
AI summary
A positive electrode for a non-aqueous electrolyte secondary battery, including a positive electrode current collector and a positive electrode active material layer present on the positive electrode current collector, wherein: the positive electrode current collector has, on at least a part of its surface on a side of the positive electrode active material layer, a current collector coating layer including a conductive material, the positive electrode active material layer includes a positive electrode active material and a conductive carbon, the positive electrode active material includes a compound represented by a formula LiFexM(1-x)PO4, wherein 0≤x≤1, M is Co, Ni, Mn, Al, Ti or Zr, the positive electrode active material layer has a porosity of 40% or less, and an amount of the conductive carbon is 0.5 to 3.5% by mass with respect to a total mass of the positive electrode active material layer.