Nonaqueous Electrolyte Battery Protective Coating
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Solution Overview
Problem
Nonaqueous electrolyte batteries with lithium manganese phosphate and titanium oxide electrodes face capacity deterioration due to state of charge deviations and side reactions caused by functional groups and adsorbed water, and existing solutions like increasing phosphorus concentration require acid washing and re-firing, which are not stable under high-temperature conditions.
Innovation Solution
A nonaqueous electrolyte battery design featuring a positive electrode with a compound like LiMn1-x-yFexAyPO4, where A is Mg, Ca, Al, Ti, Zn, or Zr, and a titanium composite oxide negative electrode, with a protective coating formed by lithium salt decomposition products, enhancing stability and reducing side reactions through controlled X-ray photoelectron spectroscopic analysis ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating component is formed by decomposition of carbonate-based electrolyte solvent, then life of lithium manganese phosphate-containing positive electrode is improved, but coating component has low stability to organic solvent and dissolves under high-temperature condition or through repetition of charge/discharge
Solution Approach 1:
The patent introduces an artificial protective coating layer as an intermediary substance between the positive electrode and electrolyte. This coating layer, formed by applying a solution containing protective coating formers (polymer compounds and/or inorganic compounds), acts as a stable mediator that prevents direct contact between the electrode and electrolyte, thereby suppressing side reactions without relying on the unstable decomposition products of carbonate-based solvents.
2Object-generated harmful factors
If phosphorus concentration in the vicinity of positive electrode surface is increased, then side reactions are suppressed, but it requires acid washing and refiring of positive electrode
Solution Approach 1:
The patent employs a simple dip-coating process where the positive electrode is immersed in a solution containing protective coating formers. This approach replaces complex acid washing and refiring operations with a straightforward coating application followed by drying, significantly simplifying the manufacturing process while achieving the same protective effect.
3Reliability
If functional groups and adsorbed water exist on titanium oxide surface, then battery shows capacity deterioration due to state of charge deviation, but removing them requires additional processing steps
Solution Approach 1:
The patent utilizes the natural properties of titanium oxide and its composite forms, which inherently possess surfaces that are less prone to adsorbing water and functional groups compared to other materials. The protective coating formers applied to the electrode surface further enhance this self-protective characteristic, creating a barrier that prevents unwanted adsorption without requiring additional complex processing steps to remove contaminants.
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 effectively suppresses side reactions and improves battery life performance by forming a stable protective coating on the positive electrode, maintaining capacity retention rates above 91% after 100 cycles at 60°C.
Implementation Method 1
a protective coating formed by lithium salt decomposition products
Implementation Method 2
a ratio (IP—F/IP—O) of a peak intensity (IP—F) of a P—F bond to a peak intensity (IP—O) of a P—O bond on the surface of the positive electrode, which are measured by X-ray photoelectron spectroscopic analysis
Data Source
AI summary
A nonaqueous electrolyte battery includes: a positive electrode containing a positive electrode active material made of a compound represented by a compositional formula of LiMn1-x-yFexAyPO4 (wherein A is at least one selected from the group consisting of Mg, Ca, Al, Ti, Zn and Zr, 0≤x≤0.3, and 0≤y≤0.1); a negative electrode containing a negative electrode active material made from a titanium composite oxide; and a nonaqueous electrolyte, wherein a ratio (IP—F/IP—O) of a peak intensity (IP—F) of a P—F bond to a peak intensity (IP—O) of a P—O bond on the surface of the positive electrode, which are measured by X-ray photoelectron spectroscopic analysis, is 0.4 or more and 0.8 or less.