Secondary battery and electronic apparatus
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Solution Overview
Problem
Lithium precipitation during low-temperature charging of secondary batteries, particularly lithium-ion batteries, leads to safety risks such as swelling and burning, limiting their use in certain environments.
Innovation Solution
Incorporating specific compounds into the electrolyte and optimizing the separator's porous coating to enhance lithium ion transport and reduce precipitation, including adjusting the mass percentage of compounds A and B, contact angle, and coating weight to improve kinetic and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolyte is used in low-temperature environment, then battery can operate in cold conditions, but lithium precipitation occurs on negative electrode surface leading to safety risks
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing compound A with specific molecular structure (formula 1) and controlling its mass percentage within 5-50%. This parameter change modifies the electrolyte's physical properties including viscosity and conductivity, enabling efficient lithium ion transport at low temperatures while preventing lithium precipitation on the negative electrode surface.
Solution Approach 2:
The patent creates a composite electrolyte system by combining compound A (formula 1) with compound B (formula 2) in specific proportions. This composite approach synergizes the low-temperature performance enhancement from compound A with the cycling stability benefits from compound B, achieving both improved low-temperature charging capability and prevention of lithium precipitation.
2Speed
If compound A is added to electrolyte to improve low-temperature performance, then lithium ion transport speed increases, but electrolyte composition becomes more complex
Solution Approach 1:
The patent optimizes the mass percentage of compound A within a specific range (5-50%) to achieve the desired lithium ion transport speed enhancement while avoiding excessive complexity. By controlling this parameter, the patent balances performance improvement with composition simplicity, ensuring the electrolyte remains manageable despite the addition of compound A.
Solution Approach 2:
The patent introduces compound A with specific local molecular structure characteristics (formula 1 with defined R1-R6 groups) that provide targeted functionality for low-temperature performance. This localized structural design allows compound A to specifically enhance lithium ion solvation and transport without requiring complete redesign of the entire electrolyte system.
3Productivity
If separator porous coating is optimized to improve electrolyte infiltration, then lithium ion transport is facilitated, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the contact angle parameter between electrolyte and separator porous coating surface to enhance electrolyte infiltration. By controlling this surface property parameter, the patent improves lithium ion transport efficiency through the separator without requiring extreme manufacturing precision, as the contact angle can be adjusted through material selection and surface treatment rather than precise dimensional control.
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 electrolyte and separator configuration enhances lithium ion transport, reducing lithium precipitation and improving the battery's low-temperature performance and energy density.
Implementation Method 1
adding the compound A into the electrolyte and adjusting the mass percentage a of the compound A to be within the above ranges can effectively dilute a base electrolyte and increase a transport speed of lithium ions in the electrolyte
Implementation Method 2
when the contact angle between the electrolyte and the surface of the porous coating of the separator is within the above range, the electrolyte has a good infiltration effect on the separator, facilitating transport of the electrolyte
Data Source
AI summary
A secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The electrolyte includes a compound A represented by the following formula: R1 to R6 are each independently selected from a fluorine atom, a cyano group, a sulfo group, an aldehyde group, a substituted or unsubstituted C1-C6 alkoxy group, a substituted or unsubstituted C1-C6 alkyl group, a substituted or unsubstituted C2-C6 alkenyl group, a substituted or unsubstituted C2-C6 alkynyl group, a substituted or unsubstituted C6-C12 aryl group, and a substituted or unsubstituted C6-C12 aryloxy group. During substitution, substituents of the groups are each independently selected from a fluorine atom, a C1-C3 alkyl group, or a C2-C4 alkenyl group. A mass percentage of the compound A is 20% to 82% based on a mass of the electrolyte. The separator includes a base film and a porous coating provided on at least one surface of the base film, and a contact angle between the electrolyte and the surface of the porous coating of the separator is 0° to 36°.