Phosphonate Electrolyte Additives for Stable Lithium Secondary Batteries
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Solution Overview
Problem
Lithium secondary batteries face issues with decreased output and capacity due to surface damage of nickel-based lithium metal oxide cathode active materials, side reactions with electrolytes, and instability under extreme temperatures, necessitating improved stability and cycle life.
Innovation Solution
Incorporation of a lithium secondary battery design featuring a cathode with lithium metal phosphate, an anode, and an electrolyte containing a phosphonate-based additive, along with specific organic solvents and lithium salts, to form protective films on active materials, enhancing stability and reducing initial resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based lithium metal oxide is used as cathode active material, then high capacity is achieved, but surface damage occurs during repeated charge and discharge
Solution Approach 1:
The phosphonate-based additive performs preliminary protective action by forming a stable interface film on the cathode active material surface before damage can occur. This pre-formed protective layer prevents surface degradation during subsequent charge-discharge cycles, allowing the high-capacity nickel-based material to maintain its performance over time.
Solution Approach 2:
The phosphonate-based additive acts as an intermediary substance between the cathode active material and the electrolyte. It forms a protective interface layer that mediates interactions, preventing direct harmful contact between the nickel-based material and electrolyte components, thus reducing surface damage while preserving capacity.
2Ease of operation
If conventional electrolyte composition is used, then basic battery function is achieved, but side reactions occur between cathode active material and electrolyte
Solution Approach 1:
The phosphonate-based additive serves as an intermediary that modifies the electrolyte composition. It forms a protective interface film that acts as a barrier, preventing direct harmful interactions between the cathode active material and conventional electrolyte components, thereby eliminating side reactions while maintaining basic battery function.
Solution Approach 2:
The invention modifies the electrolyte composition by introducing phosphonate-based additives with specific chemical structure parameters (Formula 1 with specific R groups). This parameter change in electrolyte composition fundamentally alters the interfacial chemistry, preventing side reactions between the cathode and electrolyte.
3Ease of operation
If standard electrolyte formulation is used, then battery operation is maintained, but stability deteriorates under harsh environments such as high or low temperatures
Solution Approach 1:
The phosphonate-based additive fundamentally changes the chemical parameters of the electrolyte system. The specific molecular structure (Formula 1 with various R group configurations) provides temperature-resilient protective properties, enabling the battery to maintain operational stability under harsh thermal environments while preserving normal operation.
Solution Approach 2:
The electrolyte is formulated as a composite system combining conventional electrolyte components with phosphonate-based additives. This composite electrolyte composition synergistically provides both basic operational functionality and enhanced environmental stability, allowing the battery to withstand high and low temperature conditions.
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 design results in reduced initial resistance, improved low- and high-temperature capacity, and extended cycle life by stabilizing the electrode interface and suppressing material expansion, thereby maintaining consistent output and capacity.
Implementation Method 1
Incorporation of a lithium secondary battery design featuring a cathode with lithium metal phosphate, an anode, and an electrolyte containing a phosphonate-based additive, along with specific organic solvents and lithium salts, to form protective films on active materials
Implementation Method 2
an electrolyte including a lithium salt, an organic solvent, and a phosphonate-based additive
Data Source
AI summary
A lithium secondary battery according to embodiments of the present disclosure may include a cathode including a lithium metal phosphate, an anode disposed opposite to the cathode, a lithium salt, an organic solvent, and a phosphonate-based additive represented by Formula 1. The lithium secondary battery according to exemplary embodiments of the present disclosure may exhibit reduced initial resistance and improved low-temperature capacity properties and high-temperature capacity properties.