Gel Polymer Electrolyte Composition for High-Temperature Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges with the degradation of electrode materials and volatility of organic solvents, leading to safety concerns and reduced performance, especially at high temperatures.
Innovation Solution
A composition for a lithium secondary battery electrolyte is developed, incorporating a polyalkylene carbonate-based polymer with specific molecular weight and additives like lithium difluoro(oxalato)borate and fluoroethylene carbonate, which forms a stable film on electrodes, enhancing ion conductivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-aqueous electrolyte solution is used, then ion conductivity is improved, but safety deteriorates due to combustion at high temperatures
Solution Approach 1:
The patent uses a composite gel polymer electrolyte combining polyacrylonitrile polymer matrix with cyclic carbonate and chain carbonate solvents, creating a material that integrates the ion conductivity of liquid electrolytes with the safety and structural stability of solid polymers, preventing combustion while maintaining performance
Solution Approach 2:
The patent optimizes specific parameters including the ratio of cyclic to chain carbonate (1:4 to 4:1), polymer molecular weight (10,000-1,000,000 g/mol), and additive concentrations (0.01-5 wt% vinylene carbonate, 0.01-10 wt% fluoroethylene carbonate) to achieve both high ion conductivity and thermal stability up to 150°C
2Ease of manufacture
If conventional electrolyte composition is used, then manufacturing simplicity is maintained, but lifespan deteriorates due to electrode material degradation
Solution Approach 1:
The patent introduces film-forming additives (vinylene carbonate and fluoroethylene carbonate) as intermediaries that form protective interface layers on electrode surfaces, preventing direct contact and degradation between the electrolyte and electrode materials, thereby extending battery lifespan without complicating the electrolyte composition
Solution Approach 2:
The patent specifies optimal concentration ranges for additives (0.01-5 wt% vinylene carbonate, 0.01-10 wt% fluoroethylene carbonate) that maximize protective film formation while maintaining ease of manufacture through simple mixing processes
3Speed
If organic solvent is used in electrolyte, then ion mobility is improved, but volatility increases leading to performance loss
Solution Approach 1:
The patent employs a polymer gel matrix that forms a flexible network structure, trapping the organic carbonate solvents within the polymer network, which prevents solvent evaporation and leakage while maintaining ion mobility through the gel structure
Solution Approach 2:
The patent creates a composite gel structure combining polyacrylonitrile polymer with cyclic and chain carbonates, where the polymer phase provides structural integrity to prevent volatility while the carbonate phases maintain ion conductivity
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 solution improves the battery's lifespan and safety by reducing side reactions, preventing thermal runaway, and maintaining performance at both room and high temperatures.
Implementation Method 1
a polyalkylene carbonate-based polymer including a unit represented by Formula 1 below and having a weight average molecular weight of 1,000 g/mol to 1,500,000 g/mol
Implementation Method 2
Composition for electrolyte of lithium secondary battery, gel polymer electrolyte, and lithium secondary battery including gel polymer electrolyte
Implementation Method 3
the composition either includes lithium difluoro(oxalato)borate and lithium bis(oxalato)borate at a weight ratio of 1:5 to 5:1, or includes a compound represented by Formula 3-1 below in an amount of 0.01 wt % to 5 wt % and a compound represented by Formula 3-2 below in an amount of 0.01 wt % to 10 wt % based on the total weight of the composition
Data Source
AI summary
The present invention relates to a composition for an electrolyte of a lithium secondary battery, a gel polymer electrolyte including a polymerization product thereof, and a lithium secondary battery including the gel polymer electrolyte, the composition including a lithium salt, a polyalkylene carbonate-based polymer including a unit represented by Formula 1 below and having a weight average molecular weight of 1,000 g/mol to 1,500,000 g/mol, and an organic solvent, wherein the composition either includes lithium difluoro(oxalato)borate and lithium bis(oxalato)borate at a weight ratio of 1:5 to 5:1, or includes a compound represented by Formula 3-1 in an amount of 0.01 wt % to 5 wt % and a compound represented by Formula 3-2 in an amount of 0.01 wt % to 10 wt % based on the total weight of the composition.