Silicon-Filled Thermal Paste for EV Battery Safety
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Solution Overview
Problem
Existing heat-conducting silicone compositions for lithium ion batteries in electrical vehicles face challenges with high density, cost, and combustibility, particularly due to the use of small silicon particles which increase viscosity and pose safety hazards, while larger particles may be unsuitable for filling gaps effectively.
Innovation Solution
The development of crosslinkable heat-conducting silicone compositions containing predominantly rounded metallic silicon particles with a median diameter of 30-150 μm, a broad particle size distribution, and low silicon particle content below 2 μm, which enhance thermal conductivity and reduce combustibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If small silicon particles (smaller than 20 μm) are used as thermally conductive filler, then thermal conductivity is improved, but combustibility increases and dust explosion hazard arises
Solution Approach 1:
The patent changes the particle size parameter from smaller than 20 μm to 20-100 μm, which fundamentally alters both the thermal conductivity and combustibility characteristics. This parameter change resolves the contradiction by selecting an optimal range that maintains adequate thermal conductivity while eliminating dust explosion hazards and reducing combustibility
Solution Approach 2:
The patent uses silicon particles as a composite filler material within the silicone composition. By carefully controlling the particle size distribution (20-100 μm) and combining with the silicone matrix, it achieves a composite material that balances thermal conductivity with safety properties, avoiding the extreme combustibility of fine particles
2Temperature
If ground silicon particles are used as thermally conductive filler, then thermal conductivity is improved, but viscosity increases significantly
Solution Approach 1:
The patent changes the particle size parameter from fine ground particles to coarser particles in the 20-100 μm range. This parameter change reduces the specific surface area, thereby decreasing the polymer binding and reducing viscosity while maintaining adequate thermal conductivity
Solution Approach 2:
The patent applies a size distribution strategy where particles of 20-100 μm are used, creating local optimization in different regions of the composition. The broader size range allows smaller particles to fill gaps between larger particles, maintaining thermal pathways while the overall coarser distribution keeps viscosity manageable
3Temperature
If high filling levels of silicon particles are used, then thermal conductivity is improved, but processability deteriorates
Solution Approach 1:
The patent changes the particle size parameter to 20-100 μm, which allows higher filling levels to be achieved without excessive viscosity increase. The coarser particle size reduces polymer binding, enabling higher filler content while maintaining processability
Solution Approach 2:
The patent creates a composite material system where silicon particles (20-100 μm) are combined with silicone in optimized ratios. This composite approach enables high filling levels (up to 90 wt% or more) while maintaining adequate processability through the synergistic interaction between the coarser particles and the polymer matrix
4Temperature
If ceramic fillers (aluminium oxide) are used as thermally conductive filler, then thermal conductivity is improved, but weight increases significantly
Solution Approach 1:
The patent replaces heavy ceramic fillers like aluminium oxide with silicon particles that have lower density. While silicon particles may have shorter thermal conductivity pathways compared to ceramics, they provide adequate thermal management with significantly reduced weight, making them suitable for applications where weight is critical
Solution Approach 2:
The patent uses silicon particles as a lighter alternative filler material in the silicone composite. This composite material approach achieves thermal conductivity improvement while maintaining lower density compared to ceramic-filled composites, optimizing the weight-conductivity trade-off
5Temperature
If metallic fillers (aluminium powder, silver powder) are used as thermally conductive filler, then thermal conductivity is improved, but electrical conductivity increases which is unacceptable
Solution Approach 1:
The patent replaces conductive metallic fillers with silicon particles that provide adequate thermal conductivity while maintaining electrical insulation. Silicon, being a semiconductor with extremely low electrical conductivity, serves as a functional substitute that eliminates the electrical conductivity problem while maintaining thermal management capability
6Object-affected harmful factors
If silicon particles with median diameter of 30-150 μm are used, then combustibility is reduced and processing is improved, but gap filling capability may be compromised
Solution Approach 1:
The patent changes the particle size parameter to a specific range (30-150 μm median diameter) that optimizes the balance between safety and functionality. This parameter change reduces combustibility compared to finer particles while the size distribution ensures adequate gap filling capability through proper particle packing
Solution Approach 2:
The patent applies a size distribution strategy within the 30-150 μm range, where the variation in particle sizes allows smaller particles to fill gaps and voids between larger particles. This local quality variation ensures adequate gap filling capability while maintaining the overall benefits of the coarser particle size distribution
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 achieves a thermal conductivity of at least 0.6 W/mK, low density, and compliance with the UL94 V-0 combustibility class, making it suitable for use as a gap filler in lithium ion batteries while ensuring safety and processing feasibility.
Implementation Method 1
at least 20% by volume of metallic silicon particles present as thermally conductive fillers (Z) fulfil the following features
Data Source
AI summary
Crosslinkable heat-conducting silicone compositions (Y), methods for manufacturing and using the same. Where the compositions (Y) include 5-50% by volume of a crosslinkable silicone composition (S) and 50-95% by volume of at least one thermally conductive filler (Z) having a thermal conductivity of at least 5 W/mK. The compositions (Y) have a thermal conductivity of at least 0.6 W/mK and at least 20% by volume of metallic silicon particles present as thermally conductive fillers (Z) fulfil the following features: (a) the fillers (Z) have a median diameter x50 in the range of 30-150 μm, (b) the fillers (Z) are predominately rounded, and have a width/length ratio (aspect ratio w/l) that is at least 0.76, (c) the fillers (Z) have a distribution range SPAN ((x90−x10)/x50) that is at least 0.40, and (d) the fillers (Z) contain at most 1.5% by weight of silicon particles that are smaller than 2 μm.