Lithium Battery Electrolyte Additives for High-Temperature Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face performance deterioration at high temperatures due to side reactions involving lithium salts like LiPF6, leading to SEI layer destruction and reduced cycle life, necessitating the development of effective additives to improve high-temperature storage and cycle life characteristics.
Innovation Solution
Incorporation of specific compounds such as propane sultone, propene sultone, ethylene sulfite, ethylene sulfate, and butyl propionate into the electrolyte, which react with acidic by-products like HF to form non-reactive materials, stabilizing the anode surface and reducing electrolyte decomposition, thereby enhancing high-temperature performance and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as the lithium salt in the electrolyte, then the battery can operate with basic lithium ion conduction, but side reactions occur producing HF which destroys the SEI layer and causes cathode dissolution, especially at high temperatures
Solution Approach 1:
The patent introduces specific compounds (e.g., sultone derivatives, cyclic carbonates) as intermediary substances in the electrolyte that react with HF to form stable, non-corrosive products. These intermediary compounds act as HF scavengers, preventing HF from attacking the SEI layer and cathode materials, thus resolving the contradiction between maintaining basic battery operation and preventing harmful side reactions
Solution Approach 2:
The patent converts the harmful HF by-product into a beneficial protective mechanism by designing additives that preferentially react with HF to form stable compounds. The harmful HF generation from LiPF6 decomposition is transformed into a controlled reaction that produces protective films or stable salts, turning the harmful side reaction into a beneficial protective action against further degradation
2Reliability
If conventional electrolyte additives are used to prevent by-product formation, then some protection is provided, but the operation efficiency is still lowered due to numerous side reactions including LiF and PF5 formation
Solution Approach 1:
The patent optimizes the concentration ratios of different electrolyte components, particularly the ratio of lithium salt to additive compounds, to minimize side reactions. By carefully controlling the amount of HF-generating LiPF6 relative to HF-scavenging additives, the patent reduces the absolute quantity of harmful by-products formed while maintaining adequate protective action, thus improving operation efficiency without sacrificing protection
3Power
If the battery operates at high temperatures, then energy delivery is improved, but the deterioration of battery performance accelerates due to increased HF production and SEI layer destruction
Solution Approach 1:
The patent employs additives that preemptively react with HF as soon as it is generated, even at high temperatures, to form stable protective compounds before HF can attack the SEI layer or cathode. This preliminary protective action ensures that even under high-temperature conditions where HF generation is accelerated, the battery maintains stability because the protective mechanism is already in place and actively neutralizing harmful by-products
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 improves the battery's high-temperature performance and cycle life by inhibiting side reactions and maintaining capacity and recovery capacity, with m-methylbenzoic acid methylammonium exhibiting high solubility and effectiveness in achieving uniform improvements.
Implementation Method 1
certain compounds which are capable of lowering a concentration of a hazardous material causing deterioration of the battery performance, through a chemical reaction of that compound with such an undesirable material
Implementation Method 2
the lithium ions react with carbon atoms of the anode to form a passivation film, called Solid Electrolyte Interface (SEI), on the anode surface
Implementation Method 3
PF5, which subsequently reacts with H2O to result in formation of HF
Data Source
AI summary
Disclosed is a lithium secondary battery comprising a cathode including a lithium-containing transition metal oxide, an anode including a carbon-based material, and a non-aqueous electrolyte with addition of a compound (A) and a compound (B) of formula (1). Incorporation of the compounds (A) and (B) into the electrolyte significantly improves the high-temperature performance and cycle life characteristics of the battery.