Secondary Battery Electrolyte for Fast Charging and Tab Heat Stability
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Solution Overview
Problem
Lithium-ion batteries face rapid decomposition of electrolytic solutions at the tab during fast charging, leading to increased temperature, reduced lithium salt content, and accelerated impedance, which shortens the battery's cycle life and deteriorates performance.
Innovation Solution
A secondary battery design incorporating an electrolytic solution with a heat-stable salt and an additive that inhibits lithium salt decomposition, along with a fluorinated solvent, to manage temperature rise and maintain electrolyte stability, featuring a positive electrode tab with a controlled temperature rise coefficient and optimized concentrations of heat-stable salt and additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the C-rate of the battery is increased to shorten charge time and increase discharge power, then the charging speed and discharge power are improved, but the temperature rise coefficient at the tab increases significantly, leading to accelerated decomposition of the electrolytic solution and rapid increase in SEI impedance
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by introducing a heat-stable salt with specific molecular structure (My+(SO2N)xSO2R2) and fluorinated additives. This parameter change allows the electrolyte to maintain stability at higher temperatures, enabling fast charging without the same degree of thermal degradation and electrolyte decomposition that would normally occur, thus resolving the contradiction between charging speed and temperature rise.
2Power
If the C-rate of the battery is increased to increase discharge power, then the power output is improved, but the temperature rise coefficient at the tab increases, causing accelerated decomposition of electrolytic solution and deterioration of battery performance
Solution Approach 1:
The patent modifies the electrolytic solution composition by incorporating heat-stable salt and fluorinated additives, changing the chemical parameters to enhance thermal stability. This allows the battery to operate at high discharge powers without the rapid performance deterioration that would normally result from thermal degradation and electrolyte decomposition.
Solution Approach 2:
The heat-stable salt and fluorinated additives act as intermediary substances that mediate between the high current density conditions (caused by high C-rate discharge) and the electrolytic solution. These intermediaries protect the electrolyte from thermal decomposition and prevent the formation of harmful byproducts, thereby maintaining battery performance stability during high-power discharge.
3Object-affected harmful factors
If the tab cross-sectional area is increased to reduce temperature rise coefficient, then the thermal stability is improved, but the volume energy density of the battery core decreases
Solution Approach 1:
Instead of changing the physical dimension parameter (tab area), the patent changes the chemical composition parameter of the electrolytic solution by adding heat-stable salt and fluorinated additives. This chemical parameter change allows the system to tolerate higher temperature coefficients without degradation, thus maintaining small tab dimensions and high volume energy density while still achieving thermal stability during fast charging.
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 effectively reduces electrolyte decomposition, enhances heat stability, and prolongs battery life by maintaining power and performance throughout the battery's cycle life, even under high-rate charge and discharge conditions.
Implementation Method 1
the electrolytic solution contains a heat stable salt and an additive that inhibits decomposition of the lithium salt
Implementation Method 2
an additive that inhibits decomposition of the lithium salt
Implementation Method 3
an additive that inhibits decomposition of the lithium salt
Data Source
AI summary
The present disclosure provides a fast charge long lifetime secondary battery, a battery module, a battery pack, and a power consumption device. In some embodiments, a secondary battery, comprising an electrode assembly and an electrolytic solution, the electrode assembly comprises a positive electrode plate, a negative electrode plate, and a separator, the positive electrode plate comprises a positive electrode tab, and the negative electrode plate comprises a negative electrode tab are provided. In those embodiments, the positive electrode tab has the following temperature rise coefficient:α=C10S1where S1 is a total cross-sectional area of the positive electrode tab, in unit of mm2; C is capacity of the electrode assembly, in unit of A·h; the electrolytic solution contains a heat stable salt and an additive that inhibits decomposition of the lithium salt.