8 Failure Mechanisms in EV Battery Thermal Runaway: Prevention Solutions & Mitigation Strategies (2020-2025)

Battery pack for electric vehicles that prevents thermal runaway propagation between battery modules when one module overheats. The pack has interleaved insulation between modules with rigid anti-compression members to prevent insulation compression due to module swelling. This maintains thermal blocking ability. The insulation sandwiches between thermal conductive sheets to further isolate modules.

Source

High performance heat control members for separating battery cells or insulating battery components that have favorable resistance to heat propagation and fire propagation while minimizing thickness and weight of materials used. The members include reinforced aerogel composites with durability, compressibility, and thermal insulation properties for battery applications. The aerogel composites have a reinforcing phase like fibers or open-cell macroporous materials to enhance mechanical properties compared to pure aerogels. The reinforced aerogel composites have compressibility less than 25% at 25 kPa, density less than 0.3 g/cm3, and thermal conductivity less than 25 mW/mK.

Source

Battery pack case design to prevent thermal runaway propagation in multi-cell battery packs. The case has separate air passages for each cell to isolate thermal issues. This prevents thermal spread between cells if one fails, preventing domino chain thermal runaway. The cells communicate with the outside via their own passages.

Source

Circular configuration of battery cells in an aircraft electrical storage system (ESS) for electric aircraft. The ESS uses battery modules with cylindrical pressure vessels containing radially distributed battery packs around a central cooling channel. This circular layout allows even cooling and explosion containment. It enables thinner, lighter, and cheaper pressure vessels compared to flat layouts. The cells connect to the channel using conductive components with lower melting points than cell temps. This prevents thermal runaway spread.

Source

Container design to prevent propagation of thermal runaway between electrochemical cells or batteries inside. The container has a molded body and cover made of a high thermal conductivity material. The body has vertical receptacles for the cells and internal walls separating them laterally. The cover has passages above the receptacles for cell portions to protrude. A vent allows gases to escape. Seals between receptacles and headspace are breakable and selectively permeable to prevent matter transfer. This prevents thermal runaway and material spread between cells.

Source

An electrical energy storage system for electric vehicles that provides improved safety and space efficiency compared to conventional battery packs. The system uses a separate lower housing part that can be detached for servicing without removing the upper housing with the batteries. The lower part is attached to the vehicle body, while the upper part with the batteries is fixed to the body. This allows access to the batteries without removing them from the vehicle. The lower part also contains coolant ducts to cool the batteries, and intercell structures that connect the batteries and transmit forces to prevent damage in crashes. Degassing ducts in the battery compartment prevent thermal propagation by allowing vented gases to exit when a cell fails.

Source

Temperature control system for high-performance batteries in electric vehicles that prevents overheating during charging and discharging. The system uses a closed loop with a heat transfer medium that circulates between the battery pack, a heating device, condenser, pump, and collecting container. An electronic controller monitors battery temperature, cell current, and wet steam levels. It adjusts variables like pump flow, condenser temperature, and heating to maintain optimal battery temperature and prevent boiling. This two-phase immersion cooling system with evaporation and condensation mitigates thermal runaway risks.

Source

Electric vehicle thermal management system that improves safety and efficiency compared to traditional systems. The system has two loops for cooling/heating the battery and driving motor. A release mechanism allows converging the two loops when a battery thermal runaway occurs, with both fluids released into the battery to cool/extinguish it. During normal operation, a heat exchanger transfers heat from the driving motor to the battery loop. This uses motor waste heat to warm the battery instead of external power.

Source

Battery module with enhanced thermal management through strategically integrated phase change materials (PCMs) that absorb heat generated in critical battery connections. The module features a bus bar with integrated phase change members that distribute heat from connecting areas between the cell tab and bus bar, while a secondary phase change member is positioned on the top surface of the cell. This dual-phase design enables targeted cooling of high-temperature areas, particularly the connecting region between the cell tab and bus bar, while maintaining overall system thermal balance. The phase change materials are designed to absorb and release heat efficiently, preventing thermal runaway and fire hazards.

Source

Battery pack design with improved cooling to prevent overheating and degradation of the battery cells. The pack has a heat pipe adjacent to each cell that absorbs and conducts the cell's heat. A cooling device circulates a fluid through the heat pipe to extract the heat. The heat pipe has a chamber with wick structure and pillars. The chamber is partitioned into multiple sections with different numbers of pillars adjacent to the cell versus the other sections. This allows preferential flow of fluid through the section closest to the hot cell, enhancing heat transfer.

Source

Battery module design to prevent ignition and explosion in battery packs and energy storage systems (ESS). The battery module has a cell stack with alternating resealing and sealing edges around each cell. The resealing edges are weaker and allow venting/dispersal of gases and heat. Stacking the cells with zigzagged resealing edges prevents concentration of weak points on one side. This disperses vented gases, prevents high temperatures and pressures, and prevents autoignition and explosions.

Source

Battery module and pack design to mitigate thermal runaway propagation between modules. The battery module has a rectangular frame that encloses the battery cells. The corners of the frame have vent holes to disperse gas and flame if a cell experiences thermal runaway. This prevents concentrated emission at the module ends, reducing risk of adjacent module damage. The pack contains multiple modules with this design to further spread out thermal events.

Source

Diluted concentrated electrolytes for lithium-ion batteries that have reduced volatility and flammability compared to conventional electrolytes while maintaining performance. The electrolyte contains a concentrated active salt dissolved in a solvent, like carbonate, to a higher concentration than conventional levels. But it also has a diluent that disperses the salt concentration into localized regions. This reduces free solvent and vapor pressure, mitigating issues like outgassing, swelling, and fires. The diluent has lower solubility for the salt than the solvent, but high solubility overall to prevent electrode fouling. It also has properties like low flammability and viscosity to improve safety and rate capability.

Source

Battery pack and upper cover assembly to prevent thermal runaway and explosions in electric vehicle batteries. The upper cover has an improved design with an integrated exhaust system to quickly release gas buildup during overcharging or short circuits. The exhaust system has an exhaust channel between two plates, one fastened to the inner wall of the cover and the other forming the channel. This allows gas to escape when pressure increases, preventing explosions by venting it before it reaches dangerous levels.

Source

Cylindrical lithium-ion battery design that prevents internal blockages during thermal runaway to allow safe and controlled venting of gases. The battery has an electrode assembly with a wound positive electrode and negative electrode. The negative electrode has a non-facing portion wound on the inner side of the positive electrode starting end. This non-facing portion is joined to a lead that winds at least 0.75 rounds around the electrode assembly. This configuration prevents inner winding blockage by maintaining a gas pathway through the electrode assembly even if the separator melts during thermal runaway. The lead winding allows gases to escape through the hollow core of the electrode assembly.

Source

A composite coating agent for ultra-high-nickel single-crystal ternary positive electrode materials that enhances safety and stability through controlled lithium ion migration and electrolyte protection. The coating agent combines a lithium-containing oxide with a lithium-free oxide to create a uniform, leak-resistant layer on the electrode surface. The composition of the coating agent is optimized to balance the necessary lithium ion conductivity with sufficient electrolyte protection and phase stability. This coating agent enables improved lithium ion migration control, reduced electrolyte contact with the electrode surface, and enhanced material durability during charge and discharge cycles.

Source

Electrochemical cells with active prevention of dendrite growth through voltage modulation of the separator layer. The cell incorporates an anode on a current collector, a cathode on a collector, and a separator layer between them. The separator layer includes an electroactive material with varying thicknesses. A power source maintains a voltage difference between the cathode and separator below a threshold value. The separator layer's voltage can be modulated to prevent dendrite formation by increasing voltage relative to the anode or decreasing voltage relative to the anode. This active prevention mechanism allows the cell to detect dendrite growth before it causes safety issues, enabling controlled discharge of remaining energy to prevent thermal runaway.

Source

Electrolyte additives to mitigate overcharging in lithium-ion batteries. The additives are combinations of diethyl allylphosphonate and 4-fluorobiphenyl, or diethyl allylphosphonate and 1-phenyl-1-cyclohexene. Adding these compounds to the electrolyte helps prevent lithium plating, reduce cell potentials and temperatures during overcharge, and prevent electrolyte breakdown and internal shorting.

Source

Redundant fire suppression system for battery containers in an energy storage system. The system has a control container, battery containers, and a watering container. The control container has a master controller, BSC, connected to slave controllers in the battery containers via a first communication line. It also has a bank battery management system (BBMS) connected to rack battery management systems (RBMS) in the battery containers via a second communication line. The BSC receives battery temperature data from the RBMS and BBMS to detect elevated temperatures. If needed, it sends a fire suppression command to the watering container to pump extinguishing fluid into the batteries. The slave controllers can also directly control the watering container to suppress fires. This provides redundant fire suppression capabilities using interconnected containers and communication lines.

Source

Battery with reduced calorific value during internal short circuits. The battery has a Si-based negative electrode with internal pores and a high negative-to-positive capacity ratio. The porous Si negative electrode material suppresses calorific value spikes during short circuits compared to non-porous Si. The high negative capacity relative to positive helps further mitigate heat generation. This is achieved by using a Si negative electrode with internal pores and optimizing the negative-to-positive capacity ratio.

Source

Battery system that can predict the location of cells with gas leaks in a battery pack. It uses multiple sensors inside the pack to detect gas generation from individual cells. By comparing the gas detection times from the sensors, the system can predict which cell has gas and is potentially failing. This allows proactive monitoring of cell health and identifying cells that may swell or vent gas before they actually do. It involves a chamber to accelerate cell aging by heating, then measuring gas detection times from sensors inside the pack.

Source

Battery module and pack design to delay fires after thermal runaway in battery cells. The module has multiple coolant jet spray nozzles connected to tanks. Low melting point metal valves with different melting points are installed on the nozzle inlets. As a cell overheats, valves open sequentially to spray coolant from multiple nozzles, providing multiple cooling points. This delays propagation and fire suppression compared to single cooling.

Source

Detecting abnormal self-discharge in lithium ion batteries using the existing balancing function. The method involves monitoring the charge per cell during balancing. If a cell has significantly lower charge compared to others, it indicates abnormal self-discharge. This can be due to internal shorts or other issues. By monitoring charge during balancing, it allows detecting self-discharge before it causes safety issues like thermal runaway.

Source

Battery pack design to prevent fire propagation between cells if one cell ignites. The pack has multiple tubular batteries in parallel, with an interconnect tab connecting them. The batteries are arranged in sets parallel to each other in one direction, with adjacent sets in a perpendicular direction. Each set's batteries connect to cells in the other set, but only to ones farther away rather than the closest ones. This prevents a cell fire from quickly spreading to nearby cells.

Source

Battery cell and energy storage module design to reduce fire risk and mitigate propagation of fires between cells. The battery cell has an internal fire suppressant sheet that impedes fire propagation between cells. The cell also has a sealing cap plate, electrode assembly, case, and terminal. The energy storage module has multiple of these cells in a case. The internal fire suppressant sheet in each cell helps prevent fires from spreading between cells if one cell catches fire. This improves safety and reduces the risk of a catastrophic thermal runaway in the entire module.

Source

Battery pack thermal management system that provides consistent temperature across cells without complex plumbing and valves. The system uses semiconductor thermoelectric devices in direct contact with the cell surfaces to selectively cool or heat them. It involves a battery array, two heat exchange plates, and matching thermoelectric devices. The cells contact one plate for base cooling and the thermoelectrics contact the other plate for selective heating/cooling. A power bus and electronic switches allow powering the thermoelectrics through any branch. A controller monitors cell temps and adjusts thermoelectric power to balance them.

Source

Battery temperature control system for electric vehicles that uses thermoelectric modules to individually regulate temperature of specific battery locations, rather than relying on overall pack cooling. The system involves attaching thermoelectric modules directly to the battery surface. Each module has a thermoelectric element sandwiched between insulating plates. The modules can absorb or generate heat based on power input. Sensors on the battery measure local temperatures. A control unit adjusts module power to compensate for detected temperature differences. This allows targeted cooling/heating to prevent hotspots and uniformize pack temperature.

Source

Battery pack thermal management system for electric vehicles that uses thermoelectric devices to balance voltage between cells and control temperature. The system has thermoelectric devices in thermal contact with some cells to transfer current and heat between cells. It also has thermometers to measure cell temperatures. An electronic controller balances cell voltages by selectively transferring current through thermoelectric devices. This allows balancing without resistive loads that waste energy. The controller also manages temperature by controlling thermoelectric current based on cell error. This prevents excessive heating or cooling from cell imbalances. The thermoelectric devices extract waste heat from cells with imbalanced charge and inject it into cells with lower charge. This improves cell life by preventing overheating.

Source

Smart vehicle systems for detecting and responding to severe thermal events in rechargeable battery packs. The systems employ wireless communication protocols to monitor battery temperature and surrounding environment, and automatically detect nearby vehicles or pedestrians within a defined proximity. They then assess the severity of the thermal event using data from both the battery and surrounding environment, and trigger appropriate vehicle responses such as alerts, system shutdown, or control actions to mitigate the thermal event.

Source

Electrochemical cells with interlayers between the anode and cathode to prevent dendrite growth and mitigate safety issues like short circuiting and thermal runaway. The interlayer has a thickness that increases towards the cathode end. If a dendrite grows into the interlayer, it can be detected by monitoring the voltage potential. A battery management system can then discharge the cell and use the remaining energy to power other devices, removing cell energy to create a safe condition. The interlayer voltage can also be actively changed to stop dendrite growth or dissolve it.

Source

Lithium battery with improved safety against short circuits and fire hazards. The battery uses thin metallized surface composite current collectors, high shrinkage rate separators, and materials that become nonconductive upon exposure to high temperatures. This internal fuse mechanism prevents undesirable high temperature results from short circuits. The thin current collectors stop conducting at the point of contact of an exposed short circuit. This allows for a safe discharge pathway during short circuits that prevents rapid discharge and high temperatures. The high shrinkage rate separators prevent shrinkage that could increase short circuit area. The nonconductive materials become nonconductive at high temperatures to further prevent high temperature issues.

Source

A method for safeguarding electrified vehicles from thermal runaway of the high-voltage battery during flooding events. The method involves discharging the battery when it reaches a certain state of charge and receiving notifications of impending catastrophic events. If the vehicle intends to safeguard itself, the battery is disconnected from the electrical system. This prevents thermal runaway if the battery is submerged during flooding. The discharge procedure involves operating an actuator to drain the battery.

Source

Secondary battery with integrated safety vent mechanism that enables repeated use of the battery's venting system. The battery features a case with an open side and a cap plate with a vent hole. A safety vent is positioned on the cap plate, comprising multiple layers that can be magnetically controlled to seal or open the vent. This design allows the battery to be charged and discharged multiple times while maintaining its venting capabilities. The safety vent's magnetic biasing system enables precise control over venting behavior, ensuring safe operation even after multiple charge cycles.

Source

Battery pack design to reduce weight, volume and improve energy density compared to traditional battery packs. The pack uses a cell cover to support and surround pouch-type battery cells inside the pack case. The cell cover has bent portions with venting holes to discharge gas/flame from thermal runaway cells. This prevents chain reactions by guiding exhaust outward. The cell cover also allows direct mounting of pouch cells without modules, simplifying assembly and reducing weight/volume.

Source

Valve for lithium-ion battery packs that allows fire-fighting medium to be injected into the pack during thermal runaway to extinguish internal fires. The valve has a closing member that seals an injection port. When pack pressure/temperature exceeds a threshold, the closing member opens the port for medium injection. This allows an external fire suppression system to deliver cooling agent into the pack to quench cell fires. The valve is mounted on the pack enclosure and connected to a fire-fighting device.

Source

Fire suppression system for battery packs to mitigate thermal runaway events. The system involves placing suppressant canisters within the battery pack, proximate to the battery cells. These canisters contain firefighting agents that are automatically released when a cell fails or overheats. This provides targeted suppression near the source to prevent spread of thermal runaway. The canisters are dispersed among the cells in the module, reducing the need for external suppression systems.

Source

A high temperature resistant battery separator with improved safety for lithium ion batteries. The separator is made from a meta-aramid polymer with a grid structure that provides superior thermal stability compared to conventional polyolefin separators. The meta-aramid polymer has a specific structural formula and is prepared by a controlled reaction process to create a grid structure. This separator material is used in lithium battery coated separators to provide enhanced thermal resistance and prevent battery fires and explosions at elevated temperatures.

Source

Battery module and rack design to suppress fires in battery packs and prevent propagation when thermal runaway occurs. The module has a valve nozzle to feed firewater into the module if vent gas or flames are detected. An expandable member inside the module absorbs fluid to block air inlets and outlets when the valve opens. This keeps the water level high to cool cells. The rack has a water tank, pipes, and sensors to feed water into modules if runaway is detected.

Source