Safety Protection Measures for Lithium-ion Battery Packs During Penetration Scenarios

Ensuring the safety of lithium-ion battery packs during penetration incidents, such as punctures by sharp objects, is critical to preventing thermal runaway, fire, or explosion. Below are systematic approaches to enhance penetration safety through structural design, material selection, and system-level protections.

Structural Reinforcement and Impact Absorption

High-Strength Enclosure Design

Battery pack enclosures should be constructed from materials like stainless steel, aluminum alloys, or titanium alloys to withstand external impacts. For example, some designs incorporate a honeycomb or frame structure to absorb and distribute energy during penetration. The enclosure must also include a pressure-relief valve to vent gases and prevent rupture if internal pressure rises due to thermal runaway.

Internal Component Isolation

Modules within the battery pack should be separated by ceramic fiber barriers or aerogel insulation pads to delay thermal propagation in case of a penetration-induced short circuit. Additionally, mechanical buffers or crumple zones can absorb impact energy, reducing the risk of cell deformation. For instance, some battery packs use reinforced frames to act as structural members while protecting cells from damage.

Thermal Management Integration

Active cooling systems, such as liquid cooling loops or phase-change materials (PCMs), can help dissipate heat generated during a penetration event. BMS-controlled cooling can adjust flow rates based on real-time temperature data, preventing overheating. For example, glycol-based cooling systems are commonly used to maintain optimal operating temperatures.

Material Selection and Short-Circuit Prevention

Optimized Electrolyte and Separator Materials

Electrolytes should be formulated to withstand high voltages and minimize gas production during decomposition. For instance, using solid-state electrolytes or additives that enhance thermal stability can reduce the risk of explosion. Separators should melt at elevated temperatures to block lithium-ion transport and halt internal reactions, preventing short circuits.

High-Quality Adhesives and Insulation

Adhesives used in battery construction must resist shedding or forming burrs that could puncture separators. Insulating materials should be applied to high-voltage components to prevent arcing or short circuits. For example, FPC (flexible printed circuit) fuses can protect sampling lines from short-circuit risks.

Anti-Penetration Coatings and Barriers

Battery cells can be coated with fire-resistant or impact-absorbing materials, such as ceramic layers or intumescent paints, to delay thermal propagation. Additionally, placing the battery pack in a protected zone, such as between frame rails, can minimize exposure to penetration risks during collisions.

System-Level Protections and Monitoring

Real-Time BMS Monitoring and Response

The Battery Management System (BMS) should continuously monitor cell voltages, temperatures, and internal resistance. If abnormal heating or voltage drops are detected, the BMS can isolate affected modules or initiate cooling to prevent cascading failures. For example, the BMS can trigger high-voltage contactors to disconnect the battery pack within milliseconds of detecting a penetration event.

Overcurrent and Short-Circuit Protection

Fuses, circuit breakers, or PPTC (polymer positive temperature coefficient) devices can interrupt current flow during a short circuit, preventing overheating. For instance, some designs use fuse links that melt at specific current thresholds to protect the battery pack.

Post-Penetration Safety Protocols

After a penetration event, the BMS should verify the integrity of electrical connections and isolate damaged sections. For example, if a module is compromised, the BMS can redirect power to unaffected modules, ensuring continued operation while preventing further degradation. Additionally, the system should include redundant temperature sensors to detect localized overheating.

By integrating these structural, material, and system-level safeguards, lithium-ion battery packs can achieve robust penetration safety performance. Continuous testing against standards like GB/T 31485-2015 and GB 38031-2020 ensures compliance and drives innovation in safety design.