Wound Battery Cell Electrolyte for Curved-Part Impregnation
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density while minimizing side reactions, particularly in pouch-type batteries.
Innovation Solution
A battery cell design incorporating a wound electrode assembly with specific ratios of negative electrode active material layer area, a non-aqueous organic solvent composition of ethylene carbonate and ethyl propionate, and an electrolyte solution containing a lithium salt, impregnation improver, and additive, which enhances impregnation and reduces side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the negative electrode active material layer area ratio in curved parts is increased to improve energy density, then the energy density increases, but the impregnation of electrolyte solution becomes insufficient leading to increased side reactions
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte solution by introducing an impregnation improver consisting of cyclic carbonate (15-30 vol%), chain carbonate (40-60 vol%), and cyclic carboxylate (5-30 vol%). This parameter change enables the electrolyte to effectively penetrate curved parts with high negative electrode active material layer area ratios, achieving both high energy density and reduced side reactions.
Solution Approach 2:
The patent uses a composite electrolyte solution formulation combining three types of solvents (cyclic carbonate, chain carbonate, and cyclic carboxylate) with complementary properties. This composite approach leverages the high dielectric constant of cyclic carbonate for lithium salt dissolution, the low viscosity of chain carbonate for流动性, and the film-forming capability of cyclic carboxylate, achieving effective impregnation in curved electrode regions while suppressing side reactions.
2Ease of manufacture
If conventional electrolyte composition is used to simplify manufacturing, then the manufacturing process is simple, but the impregnation in curved electrode parts is insufficient
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding cyclic carboxylate (5-30 vol%) which has superior wetting and impregnation properties. This parameter change enables the electrolyte to uniformly penetrate curved electrode parts without requiring complex manufacturing processes, maintaining ease of manufacture while improving impregnation uniformity.
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 achieves reduced side reactions and maintains high energy density, ensuring efficient lithium ion transfer and improved performance in rechargeable lithium batteries.
Implementation Method 1
a lithium salt, an impregnation improver, and an additive... ensures efficient lithium ion transfer
Implementation Method 2
Electrical energy is produced by oxidation and reduction reactions when lithium ions are intercalated and deintercalated into/from the positive and negative electrodes
Data Source
AI summary
A rechargeable lithium battery includes a battery cell, wherein the battery cell may include: a wound electrode assembly, wherein the wound electrode assembly includes a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode; and an electrolyte solution impregnated in the wound electrode assembly. The wound electrode assembly may include a pair of curved parts on opposite sides thereof, and a flat part between the pair of curved parts. The electrolyte solution may include a non-aqueous organic solvent, a lithium salt, an impregnation improver, and an additive, and the non-aqueous organic solvent may include ethylene carbonate and ethyl propionate.