Battery Pack Parylene Coating Against Conductive Fluid Short Circuits
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Solution Overview
Problem
Battery packs are prone to short circuits due to water intrusion and conductive materials, such as seawater, which can enter through various entry points, leading to electrical failures and safety issues.
Innovation Solution
A battery pack design incorporating a vapor-deposited coating, specifically a poly(p-xylylene) polymer (parylene), applied to critical components like the cell module, controller, and terminals to prevent fluid intrusion and create an electrical spacing that inhibits short circuits, along with strategic spacing of weld straps and use of seals to isolate electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery pack components are exposed to conductive fluids like seawater, then electrical connections are made, but short circuits occur between electrodes or cell straps
Solution Approach 1:
The patent applies conformal coatings to battery pack components before fluid intrusion occurs. This preliminary protective action creates a barrier that prevents conductive fluids from contacting electrical components, thereby preventing short circuits before they can happen. The coating is applied to terminals, cell straps, and other electrical connections to establish protection in advance.
Solution Approach 2:
The conformal coating acts as an intermediary barrier between the conductive fluid and the electrical components. This intermediate layer prevents direct contact between the harmful conductive fluid and the electrical connections, eliminating the harmful effect without modifying the electrical components themselves or the fluid.
2Reliability
If vapor-deposited coating is applied to cell module, then protection against fluid intrusion is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple protective functions into a single conformal coating application process. The coating simultaneously provides fluid intrusion protection, electrical insulation, and corrosion resistance, eliminating the need for multiple separate protective measures and simplifying the overall manufacturing process despite the added coating step.
Solution Approach 2:
The conformal coating serves multiple functions simultaneously: it acts as a fluid barrier, provides electrical insulation to prevent short circuits, and offers corrosion protection. This multi-functionality reduces the need for multiple separate protective components or processes, thereby managing manufacturing complexity while achieving comprehensive protection.
3Reliability
If weld straps are spaced apart, then short circuit risk is reduced, but electrical connection resistance increases
Solution Approach 1:
The patent changes the electrical parameters of the weld straps by applying conformal coatings with specific dielectric properties. This allows the straps to be spaced closer together while maintaining adequate insulation, as the coating's electrical parameters provide the necessary isolation. The coating thickness and material properties are optimized to balance insulation requirements with electrical resistance constraints.
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 effectively prevents short circuits in battery packs exposed to conductive fluids with conductivities up to 18.0 S/m, ensuring reliable operation and safety by creating a barrier against water and corrosive substances while maintaining electrical integrity.
Implementation Method 1
a vapor-deposited coating applied to at least a portion of the cell module
Implementation Method 2
The vapor-deposited coating may include a hydrophobic vapor-deposited coating
Data Source
AI summary
A battery pack and a method of assembling a battery pack. The battery pack may include an outer housing; a cell module supportable by the outer housing, the cell module including a module housing, a plurality of battery cells supported by the module housing, the battery cells having an energy of at least about 60 Watt-hours, a controller operable to control an operation of the battery pack, a conductive strap electrically connected to at least one of the battery cells, a weld strap connected between the controller and the conductive strap, and a terminal electrically connected to the battery cells and operable to connect the battery cells to an electrical device for power transfer; and a vapor-deposited, hydrophobic nano coating applied to at least a portion of the cell module.