Thermal Management in Electric Vehicle Batteries

Electric vehicle (EV*) battery modules are designed with a primary objective: generating maximum power in the smallest possible volume. However, as power density increases in confined spaces, heat generation rises correspondingly, and uncontrolled heat production during fault conditions creates safety risks. Designing high-performance battery modules that maintain safe operation under all fault conditions requires careful attention to thermal management. Beyond designs that ensure proper thermal management, inter-cell insulation methods in battery production are considered necessary to provide additional protection. What is thermal management and why is it important? Temperature plays a significant role in the longevity, efficiency and safety of a battery cell or electronic component. Temperature must be maintained constant and distributed evenly. Despite this, reliable thermal management presents challenges for manufacturers because excessive heat develops for many different reasons. Because EV battery cells are designed to have higher energy density to improve performance and reduce weight, more heat is generated in a smaller area. Electronic components are miniaturized, functions are integrated, allowing more elements to fit onto printed circuit boards (PCBs) and in confined spaces. However, the more compact and powerful PCBs become, the more heat they generate. Thermal management safely distributes excessive heat from a battery or electronic component, thereby ensuring efficient operation and preventing burnout. • In EV batteries, this process typically involves wrapping or encapsulating the component with thermal interface material (TIM), also known as gap filler. • In electronic devices, TIM is generally applied directly to the surface of electronic components. • Inter-cell insulation foams are used inside batteries.

Heat dissipation to prevent overheating of printed circuit boards

Heat can accumulate in tiny air gaps within electronic devices, causing the circuit board to overheat and stop functioning. This is where thermal mastics come into play. TIM fills these air gaps, allowing heat to transfer rapidly from heat-generating components to heat-dissipating components. This keeps the electronic device within the optimal temperature range, allowing it to operate longer and demonstrate greater durability. Thermally conductive interface materials have very high viscosity and contain highly abrasive fillers that cause excessive wear on wetted parts of equipment such as pumps, shafts and seals. Conventional distribution systems do not meet production durability requirements, leading to increased downtime and equipment maintenance costs. Frequent tightening or replacement of pumps, shafts and seals results in excessive production downtime and maintenance costs. Proper mixing and application of thermally conductive materials can also be challenging. These pastes are typically two-component materials requiring sensitive and proportional distribution. Additionally, since applications require large material volumes, distributing equal amounts of material precisely is critical to prevent air gaps or overflow. Dispensing systems used in thermal mastics (TIMs) must meet the following requirements: • Components with wear resistance that withstand the most demanding conditions, • Precise and repeatable dispensing that correctly distributes material for low or high flow applications, • Data downloads that diagnose issues before they cause downtime (process data and work logs), • Easy integration with automation equipment. In addition to thermal mastics application, two-component materials such as silicone, silicone foam, epoxy, epoxy foam and polyurethane foam are mixed and dispensed into modules to fill spatial gaps between cells to provide inter-cell insulation. Encapsulating cells with these specialized materials can prevent thermal drift and thermal spread and reduce mechanical shock and vibration under normal use conditions. Through these improvements, enhancements are achieved in safety, mechanical stability and long-term battery performance. Encapsulation foam is critical in counteracting the difficulties mentioned above because it prevents thermal spread and mechanically secures each cell in the package. However, material processing and application can create other concerns. Inadequate and/or improper mixing of two-component materials results in inhomogeneous foam formation, negatively affecting performance. Inadequate fluid supply can also lead to insufficient or excessive material volume, causing product loss. At these stages, Graco offers different system solutions. Equipment with high dosing precision is provided both for mixing ratios in two-component chemicals and for correct amounts to be applied. These equipment feature special materials and designs to provide the same precision even in TIM applications with highly abrasive effects.   *EV : Electric vehicle Excerpts from Graco website.   Haldun Bakkal Paints and Coatings, Mastics Application and Fluid Transfer Equipment Sales Manager Genmar