Battery Electrode Film Structure for Thin Separator Insulation
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Solution Overview
Problem
The thickness of conventional resin-based separators in secondary batteries limits the number of electrode layers per unit volume, reducing battery capacity and causing deterioration in cycle performance due to repeated charging and discharging.
Innovation Solution
A stack structure incorporating a first film with inorganic material particles and a polymer, where the HSP distance ratio (Ra02/Ra01) is controlled to 1.5 or less, ensures a dense insulation layer that suppresses self-discharge and maintains insulation properties even with reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the separator thickness is reduced to increase battery capacity, then the number of electrode layers per unit volume increases, but the mechanical strength and durability of the separator deteriorate
Solution Approach 1:
The patent applies composite materials by combining organic resin fibers with inorganic material particles to form a separator with enhanced mechanical properties. The inorganic particles (such as metal oxides or ceramics) are dispersed within the resin fiber matrix, creating a composite structure that provides both the flexibility of organic materials and the strength of inorganic materials, enabling thinner separators with improved durability
Solution Approach 2:
The patent utilizes porous materials by forming the separator as a nonwoven fabric with controlled porosity. The porous structure allows for ion transport while the interconnected fiber network provides mechanical strength. The porosity is optimized to balance ion conductivity and structural integrity, enabling the separator to maintain strength at reduced thickness
2Quantity of substance
If the separator thickness is reduced to improve battery capacity, then more electrode layers can be housed per unit volume, but the insulation performance and prevention of internal short circuits deteriorate
Solution Approach 1:
The composite structure of organic resin fibers and inorganic material particles creates a separator with enhanced insulation performance. The inorganic particles fill gaps between fibers and provide additional insulation barriers, while the resin matrix maintains electrical isolation. This composite approach ensures reliable insulation even at reduced thickness, preventing internal short circuits while maximizing battery capacity
3Reliability
If a conventional resin film separator is used to ensure insulation, then the separator provides basic separation, but the cycle performance deteriorates due to repeated charging and discharging
Solution Approach 1:
The patent employs composite materials where inorganic material particles are incorporated into the resin fiber matrix. The inorganic particles (such as metal oxides or ceramics) provide dimensional stability and resistance to mechanical degradation during repeated charging and discharging cycles. This composite structure maintains insulation performance and structural integrity over extended cycle life, significantly improving durability compared to conventional resin-only separators
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 enhances battery capacity by allowing thinner separators while maintaining insulation and preventing internal short circuits, thus improving cycle performance and reducing self-discharge.
Implementation Method 1
the first film including inorganic material particles having a median diameter D50 of 0.6 μm or less and a polymer, the first film having an average pore diameter of 0.5 μm or less, and the first film satisfying the following formula (1): 0Ra02/Ra01≤1.5 where Ra01 is a HSP distance between the inorganic material particles and n-methyl-2-pyrrolidone based on Hansen solubility parameter values (HSP values), and Ra02 is a HSP distance between the inorganic material particles and the polymer based on Hansen solubility parameter values (HSP values)
Data Source
AI summary
According to one embodiment, a stack includes a first active material-containing layer provided in at least a surface of a first current collector and a first film covering at least a part of a surface of the first active material-containing layer including inorganic material particles having a median diameter D50 of 0.6 μm or less and a polymer. The first film has an average pore diameter of 0.5 μm or less, and satisfies formula (1) of 0<Ra02/Ra01≤1.5, where Ra01 is a HSP distance between the inorganic material particles and n-methyl-2-pyrrolidone based on Hansen solubility parameter values, and Ra02 is a HSP distance between the inorganic material particles and the polymer based on Hansen solubility parameter values.