Electrolyte Additive Composition for High-Nickel Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with high-temperature instability, leading to oxygen release and reduced performance, necessitating improved protection for the positive electrode and enhanced rate performance and storage gas production.
Innovation Solution
An electrolyte solution containing sodium hydrosulfite as an additive, which forms a low-resistance interface film on the electrodes, reducing initial discharge capacity ratio (DCR) and storage gas production, and improving rate performance through synergistic effects with other additives like 1,3-propane sultone and fluoroethylene carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-nickel ternary positive material is used to increase energy density, then the battery capacity is improved, but the material becomes unstable at high temperature and high voltage, causing oxygen release and reduced battery life
Solution Approach 1:
Sodium hydrosulfite acts as an intermediary substance that mediates between the high-nickel ternary positive material and the electrolyte. It preferentially reacts to form a stable interface film that prevents direct contact and harmful reactions between the positive material and electrolyte, thereby maintaining battery life while preserving high capacity
Solution Approach 2:
Sodium hydrosulfite performs preliminary action by forming a protective interface film on the positive electrode surface before the battery undergoes high-temperature or high-voltage stress. This pre-formed film acts as a barrier that prevents oxygen release and degradation during subsequent operation
2Reliability
If conventional electrolyte additives are used to protect the positive electrode, then stability is improved, but the initial DCR and rate performance deteriorate
Solution Approach 1:
The invention changes the chemical parameters of the electrolyte additive by using sodium hydrosulfite with specific concentration (0.01-0.5 wt%). This parameter optimization allows the additive to form a conductive interface film that provides both stability and good ionic conductivity, avoiding the trade-off between protection and performance
3Reliability
If the concentration of electrolyte additives is increased to improve protection, then electrode stability is enhanced, but the initial DCR and storage gas production increase
Solution Approach 1:
The invention optimizes the concentration parameter of sodium hydrosulfite to a specific range (0.01-0.5 wt%). At this optimized concentration, the additive forms an effective protective film without excessive gas generation, resolving the contradiction between protection level and harmful byproducts
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 sodium hydrosulfite in the electrolyte solution effectively reduces initial DCR, low-temperature storage gas production, and enhances discharge rate performance, improving the overall performance of lithium secondary batteries.
Implementation Method 1
the sodium hydrosulfite is used as the additive, an interface film may be formed by the sodium hydrosulfite on surfaces of a positive electrode and a negative electrode in charging and discharging processes of the lithium secondary battery
Data Source
AI summary
Various embodiments provide an electrolyte solution, a secondary battery, a battery module, a battery pack and an electric device. In those embodiments, the electrolyte solution includes an electrolyte, a solvent and an additive, the additive including sodium hydrosulfite. Various embodiments improve an overall performance of the secondary battery, for example, initial DCR, storage gas production, a rate performance, or the like.