Non-Aqueous Battery Electrolyte Additive for High-Temperature Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with high-temperature storage characteristics and lifetime degradation due to side reactions at the positive and negative electrodes, particularly when using high-voltage nickel-based positive electrodes, leading to increased resistance and structural instability.
Innovation Solution
Incorporating a phosphoric acid-based additive with a specific structure into the non-aqueous electrolyte solution to form a protective film on the electrodes, suppressing side reactions and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-voltage nickel-based positive electrode is used to increase energy density, then capacity is improved, but electrochemical side reactions increase and structural stability deteriorates
Solution Approach 1:
A phosphoric acid-based additive is introduced as an intermediary substance between the nickel-based positive electrode and the electrolyte solution. This additive forms a protective interface layer that mediates the interaction, preventing direct harmful reactions while allowing lithium ion transport, thus resolving the contradiction between high capacity and structural stability
Solution Approach 2:
The chemical composition and structure of the electrode interface are modified by introducing the phosphoric acid-based additive. This changes the interfacial parameters (chemical stability, surface properties) to reduce side reactions and improve structural stability while maintaining the high-capacity characteristics of the nickel-based electrode
2Quantity of substance
If nickel content in NCM positive electrode is increased to secure energy density, then capacity is improved, but structural instability increases and electrolyte decomposition is promoted
Solution Approach 1:
The phosphoric acid-based additive serves as a protective intermediary layer between the high-nickel positive electrode and the electrolyte solution, preventing direct contact and reducing electrolyte decomposition while allowing necessary ionic transport
Solution Approach 2:
The additive converts the potentially harmful high reactivity of the nickel-based electrode surface into a beneficial protective effect by forming a stable interface layer that actually protects both the electrode structure and the electrolyte from degradation
3Quantity of substance
If formation process is performed to activate the battery, then capacity is improved, but resistance increases due to SEI layer formation
Solution Approach 1:
The composition and structure of the SEI layer are modified by the phosphoric acid-based additive, changing its electrical resistance properties. The additive creates an SEI layer with optimized characteristics that maintains capacity while reducing resistance compared to conventional SEI layers
4Productivity
If storage is performed at high temperatures to accelerate formation, then activation is improved, but SEI layer disintegration occurs and lifetime deteriorates
Solution Approach 1:
The phosphoric acid-based additive creates a pre-protective interface layer before high-temperature storage conditions can cause damage. This cushioning layer stabilizes the electrode structure and prevents HF and PF5 from disintegrating the SEI layer, allowing accelerated formation without lifetime penalty
Solution Approach 2:
The additive acts as a sacrificial protective component that consumes itself to form a stable protective layer, sacrificing the additive molecules to create a durable interface that protects the main battery components during high-temperature storage and operation
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 additive effectively improves high-temperature storage characteristics and extends the lifetime of lithium secondary batteries by reducing decomposition and corrosion, thereby stabilizing the electrode structure.
Implementation Method 1
incorporating, as an additive to the non-aqueous electrolyte solution for the lithium secondary battery, a phosphoric acid-based additive having a specific structure with excellent conductivity capable of forming a film that can effectively suppress side reactions on the surfaces of the positive electrode and negative electrode
Implementation Method 2
highly reactive lithium ions react with electrolytes to create compounds such as Li 2 CO 3 , Li 2 O, LiOH, and LiF, and these compounds form a solid electrolyte interface (SEI) layer on the electrode surface
Implementation Method 3
during the charging, the lithium ions from the lithium-containing transition metal oxide used as the positive electrode are moved to and inserted into the carbon material negative electrode active material used as the negative electrode
Implementation Method 4
inserting the electrode assembly and a non-aqueous electrolyte solution into the battery case
Data Source
AI summary
Provided is a non-aqueous electrolyte solution for a lithium secondary battery containing a lithium salt, an organic solvent and a phosphoric acid-based additive of specific structure. By adding the phosphoric acid-based additive according to an embodiment of the present invention to the electrolyte solution, the lithium secondary battery can significantly improve the high temperature stability.