Lithium Iron Phosphate Battery Electrolyte Additives for High Press Density
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Solution Overview
Problem
Lithium iron phosphate batteries with high press density electrodes face challenges in wettability and cycle life due to poor electrolyte interaction, leading to reduced energy density and performance at various temperatures.
Innovation Solution
Incorporating a cyclic carbonate with a double bond and a cyclic disulfonate in the electrolyte, specifically in the range of 0.5% to 4% by mass and 0.2% to 1% by mass respectively, improves the wettability and stability of the solid electrolyte interface (SEI) film, enhancing the low-temperature and cycle performance of lithium iron phosphate batteries with high press density electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the press density of the positive electrode film and negative electrode film is increased to improve energy density, then the energy density is improved, but the wettability of the electrode plate in the electrolyte is deteriorated and the cycle life is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a cyclic carboxylate component and adjusting the ratio of cyclic carbonate to chain carbonate. This parameter change modifies the electrolyte's interaction with the high press density electrode plate, improving wettability and forming a stable SEI film that prevents capacity fading, thus resolving the contradiction between energy density and cycle life
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple components: cyclic carbonate (EC, PC), chain carbonate (DMC, DEC), and cyclic carboxylate (GBL, GVL). This composite formulation synergistically improves both the wettability for high press density electrodes and the cycle stability, allowing the battery to maintain high energy density while achieving excellent cycle life
2Quantity of substance
If the press density of the electrode film is increased to improve energy density, then the energy density is improved, but the diffusion of lithium iron is difficult and the wettability is deteriorated
Solution Approach 1:
The patent modifies the electrolyte's physical and chemical parameters by adding cyclic carboxylate components (γ-butyrolactone and γ-valerolactone) which have high dielectric constants and excellent solvating abilities. This parameter change enhances the electrolyte's penetration capability into high press density electrode structures, improving lithium ion diffusion and maintaining good wettability despite the increased electrode density
3Ease of manufacture
If conventional electrolyte composition is used in high press density battery, then the manufacturing is simple, but the low-temperature performance and cycle performance are poor
Solution Approach 1:
The patent optimizes the electrolyte composition parameters by specifying precise ranges: cyclic carbonate 10-40%, chain carbonate 50-85%, and cyclic carboxylate 5-20%. These parameter adjustments maintain compatibility with existing manufacturing processes while dramatically improving cycle performance through enhanced SEI film stability and electrode wettability
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 combination of cyclic carbonate and cyclic disulfonate in the electrolyte effectively prolongs the service life and improves the cycle performance at normal and high temperatures, while maintaining excellent low-temperature performance by optimizing the SEI film impedance and electrode plate interaction.
Implementation Method 1
improves the wettability and stability of the solid electrolyte interface (SEI) film
Implementation Method 2
diffuse the lithium irons after increasing the press density
Data Source
AI summary
The present application provides a lithium iron phosphate battery. The lithium iron phosphate battery comprises: positive electrode plate comprising a positive current collector and a positive electrode film provided on the surface of the positive current collector; a negative electrode plate comprising a negative current collector and a negative electrode film provided on the surface of the negative current collector; a separator provided between the positive electrode plate and the negative electrode plate; and an electrolyte comprising an organic solvent, a lithium salt and an electrolyte additive. The electrolyte additive comprises a cyclic carbonate containing a double bond and a cyclic disulfonate represented by formula I. In formula I, A and B are each independently selected from an alkylene group having 1 to 3 carbon atoms. The disclosure can solve the problem that an electrode plate with high press density has poor wettability in the electrolyte, so that a low temperature electrochemical performance and a cycling electro chemical performance at normal temperature and high temperature of the lithium iron phosphate battery are improved, and the service life of the lithium iron phosphate battery is prolonged effectively.