Lithium Primary Battery Negative Electrode Coating
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Solution Overview
Problem
Lithium primary batteries face challenges in maintaining discharge performance both at the beginning of discharge and after storage at high temperature, as existing solutions either enhance surface activity leading to increased resistance or suppress activity but not sufficiently inhibit reactions with non-aqueous electrolytes.
Innovation Solution
A lithium primary battery with a negative electrode coated with carbon particles having fluorine-containing fine particles on their surface, formed using a coating layer precursor containing fluorinated graphite, which improves conductivity and inhibits reactions with the electrolyte, thereby maintaining low resistance and discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the surface of the negative electrode is activated to improve discharge performance, then the discharge performance at the beginning of discharge is improved, but the resistance at the surface of the negative electrode increases after storage at high temperature
Solution Approach 1:
The negative electrode surface is covered with a composite coating layer comprising carbon particles and fluorine-containing fine particles. The carbon particles provide electrical conductivity and maintain low resistance, while the fluorine-containing fine particles suppress parasitic reactions with the non-aqueous electrolyte during high-temperature storage. This composite structure simultaneously achieves both improved discharge performance and stable resistance characteristics.
Solution Approach 2:
The coating layer is applied specifically to the surface of the negative electrode where the contradiction between activity and stability occurs. The carbon particles are distributed to ensure conductivity at the surface, while fluorine-containing fine particles are positioned to inhibit reactions at the interface with the electrolyte, creating localized functional zones that address different aspects of the contradiction.
2Reliability
If a carbon powder layer is formed on the negative electrode to maintain conductivity, then the resistance at the negative electrode is reduced, but the reaction between the negative electrode and the non-aqueous electrolyte is not sufficiently inhibited during storage at high temperature
Solution Approach 1:
Instead of using a pure carbon powder layer, the invention employs a composite coating containing both carbon particles and fluorine-containing fine particles. The fluorine-containing fine particles act as a barrier that suppresses the harmful reaction between the negative electrode and the non-aqueous electrolyte during high-temperature storage, while the carbon particles maintain the necessary electrical conductivity.
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 enhances discharge performance and storage characteristics by reducing surface resistance and suppressing resistance increases during high-temperature storage, balancing conductivity and stability.
Implementation Method 1
bringing the coating layer precursor into contact with a non-aqueous electrolyte to form a coating layer on the surface of the negative electrode facing the positive electrode, the coating layer containing carbon particles each having fluorine-containing fine particles on a surface thereof
Data Source
AI summary
The invention provides a lithium primary battery including a negative electrode 12 comprising metal lithium or a lithium alloy, a positive electrode 11 including a positive electrode active material, a separator 13 interposed between the negative electrode 12 and the positive electrode 11, and a non-aqueous electrolyte. The negative electrode 12 includes a coating layer 17 on a surface thereof facing the positive electrode 11, the coating layer containing carbon particles each having fluorine-containing fine particles on the surface thereof, for the purpose of improving both the discharge performance and the high temperature storage characteristics.