Borate-Based Lithium Additive for Uniform SEI Formation
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Solution Overview
Problem
Conventional lithium secondary batteries face challenges in achieving high-rate charge and discharge characteristics, high-temperature storage characteristics, and life characteristics due to non-uniform solid electrolyte interface (SEI) formation and irreversible capacity issues caused by poor electrolyte additives.
Innovation Solution
A novel electrolyte additive composition comprising a borate-based lithium compound and a lithiated additive, such as phosphate-based or imidazole-based lithium, which forms a robust and uniform SEI, improving durability and reducing gas generation at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electrolyte additives are used, then the battery can operate, but the SEI formed is non-uniform leading to poor high-rate charge and discharge characteristics
Solution Approach 1:
The patent uses a composite electrolyte additive system comprising multiple lithium compounds (lithium difluorophosphate, lithium difluoro(oxalato)borate, and lithium tetrafluoroborate) that work synergistically to form a uniform and robust SEI layer. This composite approach addresses the non-uniformity issue by combining different additive mechanisms, enabling both high-rate charge/discharge performance and reliable SEI formation.
Solution Approach 2:
The patent optimizes the specific composition ratios and concentrations of the electrolyte additives to achieve the desired SEI properties. By carefully controlling the parameters of additive composition and concentration, the system forms a uniform SEI that supports high-rate charge and discharge operations.
2Ease of operation
If electrolyte additive amount is increased to improve SEI formation, then low-temperature output may improve, but positive electrode decomposition and oxidation reactions increase at high temperature
Solution Approach 1:
The patent precisely controls the concentration and composition parameters of the electrolyte additives to achieve optimal performance across temperature ranges. The specific formulation allows sufficient SEI formation for low-temperature operation while maintaining stability and preventing excessive oxidation reactions at high temperatures.
Solution Approach 2:
The electrolyte additives act as intermediaries that mediate between the electrolyte and electrode surfaces. They form protective SEI layers that enable low-temperature performance while the carefully selected composition prevents harmful oxidation reactions at high temperatures by controlling the chemical interactions at the electrode-electrolyte interface.
3Object-generated harmful factors
If insufficient electrolyte additive is used, then oxidation reactions are reduced, but irreversible capacity increases and output characteristics deteriorate
Solution Approach 1:
The patent optimizes the additive concentration parameters to achieve the minimum effective amount needed for forming a functional SEI layer. This optimized composition provides sufficient output characteristics and reversibility while minimizing oxidation reactions through precise parameter control.
Solution Approach 2:
The electrolyte additives self-regulate their function by forming an SEI layer that automatically prevents further harmful reactions. Once the optimal amount of additive forms the SEI, the system self-limits further oxidation reactions while maintaining the necessary output characteristics through the protective interface.
4Reliability
If high-temperature storage is performed, then battery capacity is maintained, but gas generation and resistance increase occur
Solution Approach 1:
The electrolyte additives serve as protective intermediaries that form a stable SEI layer on the electrodes. This SEI layer acts as a barrier that prevents harmful side reactions and gas generation during high-temperature storage, while allowing the battery to maintain its capacity through controlled ion transport.
Solution Approach 2:
The electrolyte additives perform preliminary protection by forming a robust SEI layer before high-temperature storage conditions cause damage. This pre-formed protective layer cushions the electrodes against thermal stress and prevents gas generation and resistance increase during subsequent high-temperature 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 composition enhances high-rate charge and discharge capabilities, suppresses gas generation and resistance increase at high temperatures, and extends battery life by stabilizing the SEI and preventing irreversible capacity growth.
Implementation Method 1
the lithium reacts with the carbon electrode to form Li 2 CO 3 , LiO, or LiOH, and thus, a film may be formed on the surface of the negative electrode. The film is referred to as 'solid electrolyte interface (SEI)'
Implementation Method 2
The SEI only passes the lithium ions by acting as an ion tunnel. The ion tunnel may prevent the collapse of a structure of the carbon negative electrode due to the co-intercalation of the carbon negative electrode and organic solvents of the electrolyte
Implementation Method 3
even in a case in which the electrolyte additive is included, since the surface of the positive electrode is decomposed or the electrolyte causes an oxidation reaction during a high-temperature reaction due to the electrolyte additive
Data Source
AI summary
An electrolyte additive composition of the present invention may improve high-rate charge and discharge characteristics and high-temperature storage and life characteristics of a lithium secondary battery and may achieve an effect of increasing reversible capacity when the electrolyte additive composition is used in an electrolyte while including a novel borate-based lithium compound as well as a lithiated additive.