Rounded Bus Bar Coating for Stable Corner Insulation

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing bus bars in power storage devices face issues with insulation failures at corner portions due to thin coating films and difficulties in winding mica sheets around complex shapes, leading to gaps and peeling, which compromise safety during abnormal states.

Innovation Solution

The bus bar features R-processed corner portions covered with an insulating film containing a silicate compound and a silicone-based material, applied using methods like spray or dip coating, ensuring a minimum thickness of 300 µm and a radius of curvature of 500 µm or more, enhancing insulation and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fluidized bed coating is used to form the coating film on the bus bar body, then the coating process is efficient and automated, but the coating film becomes thin on the corner portion causing insulation failure

Engineering Contradiction:
Improvecoating process efficiencyVSAvoidinsulation property
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The corner portion of the bus bar body is subjected to R processing (rounding) before the coating process. This preliminary geometric modification ensures that the corner portion has a curved surface that can uniformly receive the coating material during fluidized bed coating, preventing the formation of thin coating films that would compromise insulation reliability.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a mica sheet is wound around the bus bar body to provide insulation and heat resistance, then the insulation property is improved, but it is difficult to wind the mica sheet around complicated shapes causing gaps and peeling

Engineering Contradiction:
Improveinsulation propertyVSAvoidwinding operation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The mechanical winding process of mica sheets is replaced with a coating process. The insulating film is applied as a coating material that can conform to any bus bar shape, including complicated geometries, without requiring manual winding operations. This eliminates the problems of winding unevenness, gaps, and peeling while maintaining insulation and heat resistance properties.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the bus bar has a complicated shape due to spatial limitations, then the installation flexibility is improved, but it becomes difficult to apply uniform coating or wind mica sheets evenly

Engineering Contradiction:
Improveinstallation flexibilityVSAvoidcoating uniformity
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

R processing is performed on corner portions before coating to create a uniform curved geometry that facilitates even coating application. This preliminary geometric preparation ensures that even complicated bus bar shapes can receive uniform coating thickness, maintaining manufacturing precision while preserving installation flexibility.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The geometric parameter of the corner portion is changed from a sharp right angle to a curved shape with a specified radius of curvature (500 µm or more). This parameter modification enables the coating material to flow and adhere uniformly across the surface, achieving consistent coating thickness even on complicated bus bar shapes.

Inventive Principle:
Principle #35Parameter changes

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 provides stable insulation and heat resistance, preventing insulation failures and ensuring high safety in abnormal conditions by maintaining a thick insulating film on complex bus bar shapes without gaps or peeling.

Implementation Method 1

the insulating film contains a filler... the filler includes an inorganic compound... the silicate compound is at least one kind selected from a glass-based material, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

a bus bar body is covered with a mica sheet having an electrical insulation property and heat resistance... the insulating film contains a silicone-based material

Methodology Applied
Scientific EffectHeat resistance: Thermal Insulation

Implementation Method 3

a corner portion of the bus bar body is subjected to R processing... a radius of curvature (R) of the R processing at the corner portion is 500 µm or more

Methodology Applied
Scientific EffectR processing:

Implementation Method 4

a step of applying an insulating coating material to the bus bar body and then drying the insulating coating material to form an insulating film

Methodology Applied
Scientific EffectDrying: Evaporation

Data Source

PatentEP4675832A1Bus bar and method for producing same, and electric power storage device
Publication Date: 2026.01.07 IBIDEN CO LTD
  • EP4675832A1 patent drawingFigure 1~2
  • EP4675832A1 patent drawingFigure 3~4
  • EP4675832A1 patent drawingFigure 5

AI summary

To provide a bus bar capable of stably ensuring an insulation property, a method for producing a bus bar, and a power storage device. A bus bar (1) for use in a power storage device including a battery cell includes a bus bar body (5) containing a conductive material and covered with an insulating film (10). A corner portion (7) of the bus bar body (5) is subjected to R processing. A method for producing the bus bar (1) includes a step of performing R processing on the corner portion of the bus bar body (5) containing a conductive material, and a step of applying an insulating coating material to the bus bar body (5) and then curing the insulating coating material to form the insulating film (10). A power storage device includes a plurality of battery cells or battery modules connected to each other by the bus bar.