Silicon-Carbon Anode Battery Electrolyte for Heat and Cold Balance
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Solution Overview
Problem
Commercially available secondary batteries fail to meet demands for high energy density and effective electrochemical performance, especially in terms of high-temperature cycle and storage performance, and low-temperature direct current resistance.
Innovation Solution
A secondary battery design incorporating a negative electrode with a silicon-based and carbon material active combination, a separation film with a specific thickness and porosity, and an electrolyte comprising ethylene carbonate, ethyl methyl carbonate, and optionally dimethyl carbonate, along with lithium bisfluorosulfonimide and lithium hexafluorophosphate, to enhance energy density, high-temperature stability, and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the energy density is increased by using silicon-based negative electrode materials, then the battery capacity is improved, but the volume expansion and poor electrochemical performance worsen
Solution Approach 1:
The negative electrode uses a composite structure combining silicon-based materials (providing high capacity) with carbon materials (providing structural stability). This composite approach allows the battery to achieve high energy density while maintaining good electrochemical performance and cycle stability, resolving the contradiction between capacity and reliability.
2Device complexity
If conventional electrolyte compositions are used, then the battery structure is simple, but the high-temperature cycle and storage performance deteriorates
Solution Approach 1:
The electrolyte uses a specific composition ratio with ethyl methyl carbonate (EMC) as the main solvent (60-95 wt%) and ethylene carbonate (EC) as additive (5-40 wt%), with lithium bisfluorosulfonimide and lithium hexafluorophosphate salts. This optimized parameter combination significantly improves high-temperature cycle and storage performance while maintaining reasonable structural simplicity.
3Volume of stationary object
If the separation film thickness is reduced to improve energy density, then the battery volume is reduced, but the low-temperature direct current resistance increases
Solution Approach 1:
The separation film is optimized to a thickness of 3-10 μm, which is thin enough to maintain high energy density and small battery volume, yet thick enough to provide adequate mechanical strength and ionic conductivity. This optimal parameter range resolves the contradiction between miniaturization and low-temperature performance.
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 battery achieves good high-temperature cycle and storage performance, as well as low low-temperature direct current resistance, with improved power and cycle performance due to the specific composition and structure of the negative electrode, separation film, and electrolyte.
Implementation Method 1
an electrolyte, the electrolyte including an organic solvent, wherein the negative active material includes a silicon-based material and a carbon material
Implementation Method 2
a separation film, the separation film including a base material and a coating arranged on at least one surface of the base material
Data Source
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AI summary
The application provides a secondary battery and a device including the same. The second battery includes: a negative electrode plate, the negative electrode plate including a negative active material; a separation film, the separation film including a base material and a coating arranged on at least one surface of the base material; and an electrolyte, the electrolyte including an organic solvent, where the negative active material includes a silicon-based material and a carbon material; thickness of the base material of the separation film is 7µm~12µm; and the organic solvent includes ethylene carbonate, and a weight ratio of the ethylene carbonate in the organic solvent is ≤20%. The secondary battery and the device including the same, which are provided by the application, in the premise of having high energy density, can also have good high-temperature cycle performance, good high-temperature storage performance, and low low-temperature direct current resistance.