Lithium Battery Electrolyte Ratio for High-Temperature Gas Control
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Solution Overview
Problem
Lithium secondary batteries suffer from structural deformation, gas generation, and reduced lifespan due to high-temperature exposure and side reactions, leading to battery swelling and increased internal resistance.
Innovation Solution
A lithium secondary battery design incorporating a specific ratio of ethylene carbonate to propylene carbonate in the electrolyte, along with an additive like fluoroethylene carbonate, and a combination of polycrystalline and single-crystalline positive electrode active materials, enhances low-temperature performance and alleviates electrode delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolyte compositions are used, then the battery can operate at high temperatures, but gas generation increases and high-temperature storage performance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific ratio of cyclic carbonate (EC: 15-30 vol%, PC: 70-80 vol%) and chain carbonate (DMC: 5-20 vol%, DEC: 5-20 vol%) components. This parameter optimization reduces gas generation at high temperatures while maintaining operational stability, directly resolving the contradiction between high-temperature performance and gas generation.
Solution Approach 2:
The patent uses a composite electrolyte system combining multiple carbonate solvents (cyclic and chain types) with complementary properties. The cyclic carbonates provide high dielectric constant for lithium salt dissolution, while chain carbonates provide low viscosity for ion mobility. This composite approach achieves both high-temperature stability and reduced gas generation that single-component electrolytes cannot accomplish.
2Duration of action of moving object
If repeated charging and discharging occur, then the battery provides energy cycling, but structural deformation of lithium metal oxide occurs and lifespan characteristics deteriorate
Solution Approach 1:
The patent applies preliminary protective action by using the optimized electrolyte composition to form stable solid electrolyte interface (SEI) films on the lithium metal oxide surface before degradation occurs. The specific electrolyte formulation pre-establishes a protective barrier that prevents structural deformation during subsequent charging-discharging cycles, extending lifespan while maintaining compositional stability.
Solution Approach 2:
The patent optimizes electrolyte composition parameters (cyclic to chain carbonate ratio, specific solvent concentrations) to control the formation and stability of protective films on electrode surfaces. These parameter changes ensure that the electrolyte maintains film integrity during repeated cycling, preventing structural deformation and extending battery lifespan.
3Power
If high-temperature environments are exposed during charging and discharging, then charging speed can be maintained, but battery swelling occurs and internal resistance increases
Solution Approach 1:
The patent optimizes electrolyte composition parameters including the ratio of cyclic to chain carbonates and the specific concentrations of EC, PC, DMC, and DEC. This parameter optimization balances ion conductivity (maintaining charging capability) with thermal stability (preventing swelling and resistance increase), allowing high-power operation at elevated temperatures without compromising reliability.
Solution Approach 2:
The patent employs a composite electrolyte system where cyclic carbonates (EC, PC) provide thermal stability and film-forming properties that prevent swelling, while chain carbonates (DMC, DEC) provide low viscosity and high ion mobility that maintain charging capability. This composite material approach resolves the contradiction between power output and reliability at high temperatures.
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 battery design improves low-temperature storage performance, reduces gas generation at high temperatures, and maintains structural integrity by minimizing electrode detachment, thereby extending the battery's lifespan.
Implementation Method 1
side reactions of the electrolyte
Implementation Method 2
electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and an electrolyte that impregnates the electrode assembly
Data Source
AI summary
A lithium secondary battery according to the present disclosure may comprise a positive electrode; a negative electrode; and an electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the organic solvent may comprise ethylene carbonate (EC) and propylene carbonate (PC), wherein the additive may comprise fluoroethylene carbonate (FEC), and a volume ratio of the propylene carbonate to the ethylene carbonate in the organic solvent may be 0.2 or more and less than 4.