Electrolyte Additive for High-Temperature Lithium Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face degradation and reduced high-temperature performance due to the formation of strong acids like HF, which leads to dissolution of active materials and increased electrical resistance, causing cycle life and storage property issues, especially at elevated temperatures.
Innovation Solution
Incorporating a compound such as benzoate, phthalate, malate, or citrate into the battery electrolyte, which undergoes a chemical reaction with acids like HX (X = F, Cl, Br, or I) to decrease their concentration, thereby preventing electrode material dissolution and improving battery life and high-temperature storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes containing LiPF6 and water are used, then the battery can operate normally, but HF is formed through reaction between water and LiPF6, causing electrode material dissolution and reduced battery life at high temperatures
Solution Approach 1:
The patent converts the harmful effect of trace water in the electrolyte by introducing a compound that reacts with water to eliminate it. The reaction transforms water (harmful impurity) into beneficial products that improve electrolyte stability and prevent HF formation, thereby extending battery life at high temperatures
Solution Approach 2:
The patent introduces a compound as an intermediary substance that mediates between water and LiPF6. This compound reacts preferentially with water through hydrolysis, preventing water from reacting with LiPF6 to form HF. The intermediary compound thus protects the electrolyte system from harmful reactions
2Reliability
If cyclic carbonates with high polarity (like EC) are used as electrolyte solvents, then the battery shows good performance, but the electrolyte viscosity increases, deteriorating battery life characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a compound that reacts with water to form products with different physical properties. This modifies the electrolyte's viscosity and stability characteristics, achieving a balance between performance and longevity
3Temperature
If EC is used as electrolyte solvent to form stable protective film at anode, then low-temperature performance is improved, but EC exhibits high reactivity at high temperatures causing electrolyte decomposition and shortened battery life
Solution Approach 1:
The patent addresses EC's high reactivity at high temperatures by introducing a compound that reacts with water to eliminate the source of HF formation. This converts the harmful high-temperature reactivity into a beneficial stabilization effect, protecting the electrolyte system during high-temperature storage
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 use of these compounds significantly reduces HF concentration, preventing electrode degradation and maintaining battery performance, with improved power retention and extended cycle life even at high temperatures.
Implementation Method 1
a compound producing chemical reaction products with the exception of water through a chemical reaction with an acid (H +X (X＝F, Cl, Br or I)
Implementation Method 2
the thus-formed HF results in dissolution of cathode and anode active materials
Implementation Method 3
the electrolyte serves as a medium through which lithium ions migrate between the anode and the cathode
Implementation Method 4
Upon charging, lithium ions deintercalate from the cathode active material and intercalate into a carbon layer of the anode
Implementation Method 5
water and a lithium salt, e.g. LiPF6, present in electrodes or electrolytes, react to form a strong acid HF
Data Source
AI summary
Provided is a battery electrolyte comprising an electrolyte salt, an electrolyte solvent and a compound producing chemical reaction products with the exception of water through a chemical reaction with an acid (H+), and a secondary battery comprising the same. The battery electrolyte according to the present invention can achieve improved high- temperature storage characteristics and the life characteristics of the battery, by using a compound decreasing a concentration of HX (X = F, Cl, Br or I) through a chemical reaction with HX (X = F, Cl, Br or I) which is present in the battery and therefore causes deterioration of the battery performance.