Wound Electrode Battery Structure for Flat Current Density
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Solution Overview
Problem
Lithium batteries face issues with poor interface flatness affecting current density distribution and the use of 1,3-propanesultone as a film-forming additive, which is carcinogenic and increases manufacturing costs.
Innovation Solution
A battery design with a specific electrode assembly structure and electrolytic solution composition using film-forming additives like vinylene carbonate, halogenated carbonate, and lithium difluorophosphate, along with fillers to improve internal structure flatness and even current density distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 1,3-propanesultone is used as a film-forming additive in the electrolytic solution, then film formation on electrodes is improved, but the battery contains carcinogenic substances and manufacturing costs increase
Solution Approach 1:
The patent removes 1,3-propanesultone (the harmful film-forming additive) from the electrolytic solution and replaces it with alternative additives such as vinylene carbonate, fluoroethylene carbonate, or their mixtures. This extraction eliminates the carcinogenic substance while maintaining film formation functionality through different chemical mechanisms.
Solution Approach 2:
The patent changes the chemical composition parameters of the film-forming additives by substituting 1,3-propanesultone with vinylene carbonate (VC) and fluoroethylene carbonate (FEC) at controlled concentrations (VC: 0.5-2% by weight, FEC: 1-5% by weight). This parameter change maintains effective SEI film formation while eliminating carcinogenicity.
2Ease of manufacture
If the electrode assembly interface flatness is poor, then manufacturing is simpler, but current density distribution inside the battery is affected
Solution Approach 1:
The patent applies filler materials (such as polyethylene terephthalate, polypropylene, or their mixtures) at specific locations within the electrode assembly where thickness variations occur. This local quality adjustment compensates for interface flatness issues without requiring complex manufacturing processes, thereby maintaining both ease of manufacture and reliable current density distribution.
Solution Approach 2:
The patent incorporates filler materials into the electrode assembly structure before battery operation to pre-compensate for thickness variations and interface flatness issues. This preliminary action ensures uniform current density distribution from the first cycle without requiring post-manufacturing adjustments.
3Object-affected harmful factors
If 1,3-propanesultone is fully removed from the electrolytic solution, then carcinogenic content is reduced, but film formation on electrodes is affected and battery performance deteriorates
Solution Approach 1:
The patent introduces vinylene carbonate (VC) and fluoroethylene carbonate (FEC) as intermediary film-forming additives that perform the same protective function as 1,3-propanesultone. These intermediaries form stable solid electrolyte interface (SEI) films on the electrodes, ensuring reliable battery performance including cycle life and high-temperature storage performance without the carcinogenic effects of PS.
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
Enhances film formation on electrodes, stabilizes the SEI film, and ensures consistent battery performance while reducing the carcinogenic content, thus improving cycle and high-temperature storage performance.
Implementation Method 1
film-forming additive includes 1,3-propanesultone... enhances film formation on electrodes, stabilizes the SEI film
Implementation Method 2
The electrolytic solution includes a lithium salt, an organic ester solvent, and a film-forming additive... film formation on negative positive electrodes
Data Source
AI summary
A battery includes an electrode assembly, an electrolytic solution, a package accommodating the electrode assembly, a first tab, a second tab, and a first filler. The electrode assembly is formed by winding a first electrode plate and a second electrode plate stacked. The first current collector includes a first blank region, a first single-surface-coated region, and a first double-surface-coated region. The first blank region includes a first planar region and a first bent region. The first single-surface-coated region includes a second bent region and a second planar region. The first tab is disposed in the first planar region. The second tab is disposed on the second electrode plate. The first filler is disposed in the first planar region or the second planar region. Projections of the first filler, the first tab, and the second tab in a thickness direction of the electrode assembly do not overlap.