Battery Electrolyte Composition for Low-Temperature Dynamic Performance
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Solution Overview
Problem
Lithium ion batteries exhibit poor dynamic performance, low capacity retention, and high impedance at low temperatures, limiting their large-scale application.
Innovation Solution
A secondary battery design that includes a negative electrode plate with a specific active material layer and an electrolyte comprising a mixture of cyclic and chain ester solvents, optimized to satisfy a specific formula (Mel. × σ × Cap. × PD × η × β > 18), which improves conductivity, viscosity, and compacted density for enhanced low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte composition is used, then the battery can operate at normal temperatures, but the dynamic performance deteriorates at low temperatures with high impedance and low capacity retention
Solution Approach 1:
The patent applies parameter changes by optimizing the electrolyte composition ratios (cyclic carbonate 10-30 wt%, chain carbonate 70-90 wt%) and adjusting the Li salt concentration (0.5-2.0 M) to achieve optimal low-temperature performance. This systematic parameter optimization resolves the contradiction between maintaining reliability at normal temperatures and improving dynamic performance at low temperatures.
Solution Approach 2:
The patent uses composite materials by combining different types of carbonate solvents (cyclic and chain) with complementary properties. The cyclic carbonate provides high dielectric constant for Li salt dissolution, while the chain carbonate provides low viscosity for ion mobility, creating a composite electrolyte system that maintains both reliability and dynamic performance across temperature ranges.
2Power
If the electrolyte viscosity is reduced to improve low-temperature ion mobility, then the conductivity increases, but the capacity retention rate decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the electrolyte composition within specific ranges: cyclic carbonate 10-30 wt%, chain carbonate 70-90 wt%, and Li salt concentration 0.5-2.0 M. This optimized parameter combination achieves the balance where the electrolyte maintains appropriate viscosity for both high conductivity and good capacity retention, resolving the contradiction between power and reliability.
3Quantity of substance
If the compacted density of the negative electrode active material layer is increased to improve energy density, then the battery capacity increases, but the low-temperature dynamic performance deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the compacted density of the negative electrode active material layer within the range of 1.8-2.2 g/cm³. This controlled density optimization ensures sufficient battery capacity while maintaining adequate porosity for electrolyte penetration and ion transport, thereby resolving the contradiction between quantity of substance and low-temperature productivity.
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 optimized battery design achieves improved dynamic performance, capacity retention, and reduced impedance at low temperatures, preventing lithium precipitation and enhancing overall battery performance.
Implementation Method 1
the electrolyte comprises an organic solvent, and the organic solvent comprises a cyclic ester solvent and a chain ester solvent
Implementation Method 2
the conductivity σ of the electrolyte, and the unit of the conductivity is mS/cm;... the viscosity η of the electrolyte, and the unit of the viscosity is mPa·s
Data Source
AI summary
The present application belongs to the technical field of batteries, and particularly relates to a secondary battery. The secondary battery provided by the present application comprises a positive electrode plate, a negative electrode plate and electrolyte, wherein the electrolyte comprises an organic solvent, and the organic solvent comprises a cyclic ester solvent and a chain ester solvent; the secondary battery parameter satisfies Formula (1). The secondary battery has good dynamic performance at low temperature, and has good capacity retention rate and lower impedance under the low temperature condition by adjusting the electrolyte and the negative electrode plate and the combined action of the electrolyte and the negative electrode plate.