Cathode-Stabilizing Electrolyte Additives for High-Temperature Li Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining performance at high temperatures due to electrolyte decomposition, gas generation, and structural instability of the cathode, which degrade cycle life and safety.
Innovation Solution
Incorporation of fluorinated phosphazene-based phosphorus compounds in the non-aqueous electrolyte to form a robust cathode electrolyte interphase (CEI) layer, coordinating with transition metals to enhance cathode stability and suppress side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel NCM cathode material is used to increase energy density, then battery capacity is improved, but electrolyte decomposition and gas generation occur due to poor interfacial stability
Solution Approach 1:
A fluorinated phosphazene-based phosphorus compound is introduced as an intermediary substance between the high-nickel NCM cathode and the electrolyte. This compound coordinates with transition metals on the cathode surface to form a stable interfacial layer, preventing direct contact and harmful reactions between the electrolyte and the reactive cathode material, thereby resolving the contradiction between high capacity and interfacial stability.
Solution Approach 2:
The patent employs a composite interfacial structure formed by the fluorinated phosphazene-based phosphorus compound coordinating with transition metals on the cathode surface. This composite layer combines the high-capacity properties of NCM with the stability provided by the phosphorus compound, achieving both high energy density and improved interfacial stability.
2Duration of action of stationary object
If the cathode and electrolyte interface is stabilized to prevent decomposition, then cycle life is improved, but the complexity of electrolyte composition increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by incorporating a fluorinated phosphazene-based phosphorus compound. This specific chemical modification enables the formation of a stable cathode electrolyte interphase (CEI) layer, extending cycle life while maintaining relatively simple electrolyte formulation through the use of a single key additive component.
3Temperature
If a robust CEI layer is formed to suppress side reactions, then high-temperature performance is improved, but the manufacturing precision of electrolyte formulation becomes more critical
Solution Approach 1:
The patent optimizes the concentration parameter of the fluorinated phosphazene-based phosphorus compound in the electrolyte to achieve robust CEI layer formation at high temperatures. By carefully controlling this compositional parameter, the patent enables high-temperature performance improvement while maintaining feasible manufacturing precision through a focused optimization approach on a key additive component.
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
Improves high-temperature storage characteristics and cycle life by preventing electrolyte decomposition and gas generation, ensuring stable operation and safety of lithium secondary batteries.
Implementation Method 1
The phosphorus compound coordinates with transition metals of the cathode to enhance the stability of both the metal and the cathode active material
Implementation Method 2
capable of preventing decomposition of the electrolytes and generation of gas at the interface between a cathode and the electrolyte
Data Source
AI summary
The present invention relates to a novel electrolyte additive, a non-aqueous electrolyte for a lithium secondary battery comprising the novel electrolyte additive, and a lithium secondary battery comprising the non-aqueous electrolyte. More specifically, the present invention relates to a non-aqueous electrolyte for a lithium secondary battery comprising an additive capable of forming coordination bonds on the surface of the cathode. The present invention also relates to a lithium secondary battery having improved performance, wherein by including such a non-aqueous electrolyte, the high-temperature cycle life of the lithium secondary batteries is not degraded, gas generation is suppressed during high-temperature storage, the capacity retention and capacity recovery are improved, and the swelling (thickness expansion) of the battery during high-temperature storage is inhibited.