Non-aqueous Electrolyte for Lithium Battery SEI Stability
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Solution Overview
Problem
Lithium secondary batteries experience performance deterioration due to repeated charge/discharge cycles, particularly as capacity density increases, and existing non-aqueous electrolyte solutions form SEI films with high resistance and instability.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries incorporating a polyfunctional compound with acryl groups and an anion receptor, such as borane or borate compounds, which forms a stable SEI film and controls LiF content, combined with an aqueous binder like styrene-butadiene rubber for improved cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vinylene carbonate (VC) is added to form SEI film, then SEI film formation is improved, but the SEI film has high resistance and tends to collapse at high temperature
Solution Approach 1:
The patent combines multiple additives (vinylene carbonate VC at 0.01-5 wt%, fluoroethylene carbonate FEC at 0.01-5 wt%, and lithium fluoride LiF at 0.01-10 wt%) to form a composite SEI film on the anode. This composite approach leverages the benefits of each component: VC provides film formation, FEC enhances stability and reduces resistance, and LiF controls the composition and structure of the SEI film, resulting in a film that is both stable and low-resistance.
Solution Approach 2:
The patent optimizes the concentration parameters of each additive component to achieve the desired SEI film properties. By carefully controlling the amounts of VC, FEC, and LiF within specific ranges, the patent adjusts the composition and structure of the SEI film to balance stability and resistance characteristics.
2Quantity of substance
If capacity density of batteries is increased, then energy density is improved, but performance deterioration due to repeated charge/discharge cycles becomes more serious
Solution Approach 1:
The patent applies preliminary action by forming a stable and protective SEI film on the anode surface before the battery undergoes repeated charge/discharge cycles. The additives (VC, FEC, and LiF) pre-condition the anode surface to create a robust SEI film that prevents subsequent degradation, thereby protecting the high-capacity electrodes from performance deterioration during cycling.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by introducing specific additives that change the properties of the SEI film. This parameter change in the electrolyte composition leads to a corresponding change in the SEI film characteristics, making it more stable and protective, thus improving cycle life while maintaining high energy density.
3Reliability
If polyfunctional compound with acryl groups and anion receptor are added, then stable SEI film is formed with controlled LiF content, but device complexity increases
Solution Approach 1:
The patent employs multi-functional additives that perform multiple roles simultaneously. For example, VC and FEC serve as film-forming agents while also contributing to resistance reduction, and LiF not only controls SEI composition but also enhances film stability. This multi-functionality reduces the need for separate additives for each function, thereby limiting the increase in complexity.
Solution Approach 2:
The patent manages complexity by optimizing the concentration parameters of the additives within specific ranges (VC: 0.01-5 wt%, FEC: 0.01-5 wt%, LiF: 0.01-10 wt%). By controlling these parameters, the patent achieves the desired SEI film properties without requiring excessive amounts of additives or complex formulations, thus balancing performance improvement with formulation simplicity.
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 results in enhanced cycle life characteristics and reduced SEI film resistance, enabling higher energy density and economic, environmentally friendly battery production with increased LiF content and binding efficiency.
Implementation Method 1
forming solid electrolyte interface (SEI) films by adding a variety of compounds to non-aqueous electrolyte solutions
Implementation Method 2
an anion receptor selected from the group consisting of a borane compound, a borate compound and a mixture thereof
Implementation Method 3
non-aqueous electrolyte solution to provide channels through which lithium ions migrate between the two electrodes
Implementation Method 4
a polyfunctional compound including two or more functional groups, at least one of which is an acryl group
Data Source
AI summary
Disclosed is a non-aqueous electrolyte solution for a lithium secondary battery. The non-aqueous electrolyte solution includes an electrolyte salt and an organic solvent. The non-aqueous electrolyte solution further includes (a) a polyfunctional compound including two or more functional groups, at least one of which is an acryl group, and (b) an anion receptor selected from the group consisting of a borane compound, a borate compound and a mixture thereof. Further disclosed is a lithium secondary battery including the non-aqueous electrolyte solution. A stable solid electrolyte interface (SEI) film is formed on an anode of the lithium secondary battery. The amount of LiF in the SEI film is controlled, achieving improved cycle life characteristics of the battery.