Wound Lithium Battery Cell Electrolyte for High Energy Density
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density while minimizing side reactions, which affect their performance and efficiency.
Innovation Solution
A battery cell design incorporating a wound electrode assembly with specific ratios of negative electrode active material layer distribution and a non-aqueous organic solvent electrolyte containing ethylene carbonate, ethyl propionate, and an additive, such as lithium difluoro(oxalato)borate, to enhance energy density and reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the energy density is increased by optimizing electrode structure and electrolyte composition, then the battery capacity is improved, but side reactions between the electrolyte and electrodes increase
Solution Approach 1:
A coating layer comprising a cyclic carboxylate and a lithium salt is introduced as an intermediary between the negative electrode and the electrolyte. This coating layer acts as a protective mediator that prevents direct harmful interactions between the electrolyte and the negative electrode, thereby reducing side reactions while maintaining high energy density.
Solution Approach 2:
The coating layer is formed as a composite material combining a cyclic carboxylate (such as lithium difluoro(oxalato)borate) and a lithium salt. This composite structure provides both protective functionality to reduce side reactions and ionic conductivity to maintain battery performance and energy density.
2Quantity of substance
If the ratio of curved sections to flat section in the wound electrode assembly is increased to improve energy density, then the battery capacity increases, but the manufacturing precision and structural stability become more difficult to control
Solution Approach 1:
The patent specifies precise parameter ranges for the wound electrode assembly structure, including the ratio of curved section area to flat section area (30% to 70%) and the width of the flat section (5 mm to 20 mm). By controlling these parameters within defined ranges, the invention achieves high energy density while maintaining manufacturing precision and structural stability.
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 proposed design increases energy density and reduces side reactions, thereby improving the overall performance and efficiency of the rechargeable lithium battery.
Implementation Method 1
The positive electrode and the negative electrode include an active material in which intercalation and deintercalation may occur. The rechargeable lithium battery generates electrical energy through oxidation and reduction reactions if (e.g., when) lithium ions are intercalated and deintercalated.
Implementation Method 2
The rechargeable lithium battery generates electrical energy through oxidation and reduction reactions if (e.g., when) lithium ions are intercalated and deintercalated.
Implementation Method 3
A lithium salt dissolved in a non-aqueous (e.g., water-insoluble) organic solvent is used as the electrolyte of the rechargeable lithium battery.
Data Source
AI summary
A battery cell and a rechargeable lithium battery including the battery cell are disclosed. The battery cell may include a wound electrode assembly including a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode, and an electrolyte impregnated in/with the wound electrode assembly. The wound electrode assembly may include a pair of curved sections on two opposite (e.g., opposite facing) sides of the wound electrode assembly and a flat section between the pair of curved sections. The electrolyte may include a non-aqueous (e.g., water-insoluble) organic solvent, a lithium salt, and an additive. The non-aqueous (e.g., water-insoluble) organic solvent may include ethylene carbonate and ethyl propionate. The additive may include a compound represented by Chemical Formula 1.