Battery Electrode Mixture Surface Chemistry for Cycle Capacity Retention
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Solution Overview
Problem
The repeated charge and discharge of batteries leads to a decrease in capacity due to side reactions between the active material and the electrolyte solution, which affects the battery's cycle characteristics, and existing technologies do not effectively address this issue.
Innovation Solution
An electrode mixture for batteries that includes an active material capable of occluding and releasing lithium, with an ionic compound bonded to its surface, containing an organic cation and a counter anion, which acts as a cushioning layer to inhibit direct contact with the electrolyte solution and reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the battery undergoes repeated charge and discharge cycles, then the battery provides continuous energy storage and release, but the capacity gradually decreases due to side reactions between the active material and electrolyte solution
Solution Approach 1:
An ionic compound is introduced as an intermediary substance that bonds to the surface of the active material. This compound contains an organic cation and a counter anion, forming an intermediate layer between the active material and the electrolyte solution. The intermediary prevents direct harmful interactions while allowing necessary ionic transport, thereby reducing side reactions and improving capacity maintenance over charge-discharge cycles.
Solution Approach 2:
The invention modifies the surface properties of the active material by changing its chemical composition through the addition of the ionic compound. This parameter change in the surface chemistry creates a new interface with different interaction characteristics toward the electrolyte solution, reducing harmful side reactions while maintaining electrochemical functionality.
2Reliability
If an ionic compound is added to the electrode mixture to improve cycle characteristics, then the capacity maintenance rate increases, but the device complexity and manufacturing process become more complex
Solution Approach 1:
The invention uses a small but sufficient amount of ionic compound (0.1-5 mass% relative to active material) to achieve the desired protective effect. This partial action approach adds minimal complexity to the electrode mixture while obtaining adequate improvement in capacity maintenance, avoiding the need for excessive amounts that would significantly complicate the system.
3Reliability
If the content of ionic compound is increased to enhance the cushioning effect, then the inhibition of side reactions improves, but the cost and material loss increase
Solution Approach 1:
The invention determines an optimal range of ionic compound content (0.1-5 mass%) that provides sufficient cushioning effect to inhibit side reactions without using excessive amounts. This partial action principle identifies the minimum effective concentration needed to achieve the protective function, thereby reducing material loss and cost while maintaining reliable side reaction inhibition.
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 electrode mixture significantly improves the cycle characteristics of batteries by inhibiting side reactions, maintaining capacity over charge-discharge cycles, with optimal results when the ionic compound content is between 0.2% and 1.8% by mass relative to the active material.
Implementation Method 1
an ionic compound bonded to a surface of the active material
Implementation Method 2
the ionic compound contains a bonding moiety to the active material
Data Source
AI summary
An electrode mixture for a battery according to an embodiment of the present invention comprises an active material capable of intercalation and deintercalation of lithium, and an ionic compound bonded to the surface of the active material. The ionic compound contains a binding site to the active material, an organic cation, and a counter anion for the organic cation. The binding site is derived from, for example, a hydrolyzable silyl group. In addition, the content of the suitable ionic compound is, for example, 0.2-1.8 mass % with respect to the mass of the active material.