Bisphosphate Battery Electrolyte for High-Temperature Cathode Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with reduced output and capacity due to surface damage of nickel-based lithium metal oxide cathodes and side reactions with the electrolyte, especially in extreme temperature environments.
Innovation Solution
An electrolyte for rechargeable lithium batteries is developed, comprising an additive with a compound represented by Formula 1, an organic solvent, and a lithium salt. The additive enhances thermal and chemical stability by forming a stable SEI film on the electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based lithium metal oxide is used as cathode active material to achieve high capacity, then battery capacity is improved, but surface damage occurs during repeated charging and discharging leading to reduced output and capacity
Solution Approach 1:
A coating layer comprising a compound of Formula 1 is applied to the surface of the nickel-based lithium metal oxide cathode active material. This coating layer acts as an intermediary between the cathode material and the electrolyte, preventing direct contact and side reactions while allowing lithium ion diffusion. The coating layer stabilizes the surface of the cathode material during repeated charging and discharging, preventing surface damage and maintaining output stability.
2Quantity of substance
If nickel-based lithium metal oxide is used as cathode active material to achieve high capacity, then battery capacity is improved, but side reaction with electrolyte occurs leading to reduced lifespan
Solution Approach 1:
The coating layer of Formula 1 compound serves as a protective intermediary that physically separates the reactive nickel-based lithium metal oxide cathode material from the electrolyte. This prevents side reactions between the cathode material and electrolyte that would otherwise degrade performance over time. The coating layer remains stable during cycling, preserving battery lifespan while maintaining high capacity.
Solution Approach 2:
The compound of Formula 1 is specifically designed with adjustable parameters including aromatic rings (Ar1, Ar2), linker groups (L), and heteroatoms (X1). By optimizing these structural parameters, the coating layer achieves optimal balance between lithium ion conductivity and protective function, preventing electrolyte decomposition and cathode material degradation during long-term cycling.
3Device complexity
If conventional electrolyte composition is used to maintain simplicity, then device complexity is reduced, but thermal stability and chemical stability are insufficient in extreme temperature environments
Solution Approach 1:
The electrolyte is formulated as a composite system containing the compound of Formula 1 combined with conventional electrolyte components (cyclic carbonate, chain carbonate, and lithium salt). This composite electrolyte composition leverages the stabilizing effect of the Formula 1 compound on the cathode material surface while maintaining the beneficial properties of conventional electrolytes, achieving enhanced thermal and chemical stability without excessive complexity.
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 proposed electrolyte improves battery performance by reducing heat generation, enhancing flame retardancy, and maintaining high capacity and lifespan characteristics even at high temperatures.
Implementation Method 1
The additive enhances thermal and chemical stability by forming a stable SEI film on the electrode surface
Data Source
Figure 1~2
AI summary
An electrolyte for a rechargeable lithium battery of exemplary embodiments includes: an organic solvent; a lithium salt; and a bisphosphate-based additive, thereby providing an electrolyte for a rechargeable lithium battery capable of imparting improved flame retardant characteristics and cell performance, for example, high-temperature storage characteristics and lifespan characteristics, and a rechargeable lithium battery including the same.