Precursor Solution for Uniform Electrode Coating
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in achieving high-speed charge and discharge capabilities due to the generation of by-products on the electrode surface, which adversely affect charge and discharge characteristics and cycle life, as existing methods struggle to form dense and uniform oxide films on active materials effectively.
Innovation Solution
A precursor solution containing a lithium oxoacid salt, a base metal compound (such as Nb, Ta, or Sb), and an organic solvent is used to coat the active material particles, allowing for a dense and uniform coating with a lithium salt of the metal acid, promoting adhesion and enhancing charge and discharge characteristics through a low-temperature heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a film of oxide is formed on the surface of active material using conventional methods, then the surface coating is achieved, but the film is not dense and uniform enough
Solution Approach 1:
The invention changes the chemical composition parameters of the precursor solution by incorporating specific metal compounds (Nb, Ta, Sb) and controlling the ratio of metal salt to binder, which enables the formation of dense and uniform oxide films after heat treatment, resolving the issue of poor film quality from conventional methods
Solution Approach 2:
The invention uses a composite precursor solution containing multiple metal compounds (lithium oxoacid salt and base metal compound) that work synergistically during heat treatment to form a composite oxide film with improved density and uniformity, addressing the insufficiency of single-material coatings
2Productivity
If by-products are generated on the electrode surface during charge and discharge, then the electrochemical reactions occur, but the by-products adversely affect charge-discharge characteristics and cycle life
Solution Approach 1:
The invention applies preliminary protective action by forming a dense oxide film coating on the active material surface before electrode assembly, which prevents harmful by-products from forming during subsequent charge-discharge cycles, thereby protecting cycle life while maintaining high charge-discharge rates
Solution Approach 2:
The invention converts the harmful by-products that form during charge-discharge into beneficial effects by using the electrochemical reactions to reduce metal compounds in the coating to metallic elements, which then form protective oxide layers that actually improve electrode performance and stability
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 enables the formation of electrodes with improved charge and discharge characteristics at high loads, including high-speed charging and extended cycle life by ensuring a dense and uniform coating of the active material surface, thereby enhancing the performance of lithium ion secondary batteries.
Implementation Method 1
allowing for a dense and uniform coating with a lithium salt of the metal acid, promoting adhesion
Implementation Method 2
an organic solvent removing step of removing the organic solvent by heating the precursor solution
Implementation Method 3
a firing step of firing the molded article
Data Source
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AI summary
A precursor solution according to the present disclosure contains: an organic solvent; a lithium oxoacid salt that exhibits a solubility in the organic solvent; and a base metal compound that exhibits a solubility in the organic solvent and that is at least one base metal selected from the group consisting of Nb, Ta, and Sb.