Sulfur-Phosphorus Coated Cathode for High-Voltage Battery Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face issues with gas generation and increased internal resistance when operated at high temperatures, particularly when the upper limit voltage is set above 4.25V, leading to expansion of the battery casing and reduced capacitance.
Innovation Solution
A cathode active material is developed with sulfur (S) and phosphorus (P) incorporated near the particle surface of lithium composite oxide, forming compounds like Li2SO4 and Li3PO4, which suppresses the reaction with the electrolyte and reduces gas generation, thereby enhancing high-temperature preservation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the upper limit voltage upon charging is raised to 4.25V or more to increase capacitance, then energy density is improved, but gas generation increases due to cathode-electrolyte reaction
Solution Approach 1:
A coating layer containing sulfur and phosphorus compounds is applied to the cathode active material surface to act as an intermediary barrier. This coating layer suppresses the direct reaction between the cathode and electrolyte, thereby reducing gas generation while allowing the battery to operate at high voltages (4.25V or more) for increased energy density.
Solution Approach 2:
The chemical composition of the cathode surface is modified by incorporating sulfur and phosphorus compounds into a coating layer. This parameter change in surface chemistry creates a protective interface that reduces harmful reactions with the electrolyte, enabling high-voltage operation without excessive gas generation.
2Use of energy by moving object
If the upper limit voltage upon charging is raised to 4.25V or more to increase capacitance, then energy density is improved, but internal resistance increases
Solution Approach 1:
The sulfur-phosphorus coating layer serves as a protective intermediary that stabilizes the cathode-electrolyte interface. This reduces parasitic reactions and maintains lower internal resistance even when operating at high voltages (4.25V or more), thereby preserving reliability while achieving improved energy density.
3Object-generated harmful factors
If sulfur and phosphorus are incorporated near the particle surface of lithium composite oxide, then gas generation is suppressed, but manufacturing complexity increases
Solution Approach 1:
The coating layer formation process is merged with the existing cathode manufacturing process. Sulfur and phosphorus compounds are incorporated into the coating layer during standard cathode fabrication steps, combining the protective coating function with the base material production without requiring entirely separate manufacturing operations.
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 gas generation and internal resistance increases, ensuring excellent high-temperature preservation and maintaining sufficient capacitance, even when the battery is charged to higher voltages, thus improving the battery's performance and longevity.
Implementation Method 1
at least one kind selected from the group consisting of sulfur S and phosphorus P is contained in a portion near a particle surface of a lithium composite oxide
Implementation Method 2
forming compounds like Li2SO4 and Li3PO4
Data Source
AI summary
A secondary battery having a cathode, an anode, and an electrolyte is provided. The cathode includes a cathode active material containing at least one kind selected from the group consisting of sulfur S and phosphorus P in a portion near the particle surface of a lithium composite oxide. A content of the kind in the portion is larger than that in the particle of the lithium composite oxide.