Carbon Fiber Sleeve Tempers Battery Thermal Runaway

Power Generation and Storage
Carbon Fiber Sleeve Tempers Battery Thermal Runaway (MSC-TOPS-119)
Prevents fire hazard in small cylindrical Li-ion battery cells via propagation resistant technology
Overview
Innovators at NASA Johnson Space Center have developed a carbon fiber reinforced polymer (CFRP) sleeve, that, when fitted over a cylindrical lithium-ion battery cell, can prevent cell-to-cell propagation by containing a thermal runaway (TR) event to the originating cell. TR is caused by a battery cell short-circuiting and its inability to contain the resulting increase in pressure and temperature, which may lead to a sidewall rupture (SWR). Space flight and other industrial batteries frequently utilize multiple cells, such as the 18650, that are assembled into modules or battery packs and provide power to a variety of applications. A TR event can propagate to all the cells in a battery pack, escalating into a fire that can be catastrophic. Use of CFRP sleeves for Li-ion cells provides multiple advantages over previous containment designs: increased hazard safety, lower mass, reduced cost, lack of conductivity, and manufacture with readily available materials. Hundreds of billions of 18650 battery cells are made globally and are the most common single cell format. They are used in commercially available products such as power tools, laptops, cameras, e-bikes, and electric cars.

The Technology
The CFRP sleeve was originally intended for crewed space flight lithium-ion 18650 battery packs rated over 80 Watt-hours (Wh), which are required to be passively propagation-resistant for increased safety. Previous battery designs have addressed SWR propagation by using aluminum or steel interstitial materials to prevent SWRs from directly impacting neighboring cells, but these materials were underperforming. During testing of 18650 battery cells, it was discovered that cells over 2.6Ah in capacity can have an undesirable failure mode in which the cell wall will rupture or breach during a thermal runaway (TR) event sending heat and ejecta into an undesirable direction. TR is typically triggered when heat produced by the battery cell’s exothermic reaction leads to increased and escalating internal cell temperature, pressure, and boiling of the electrolytes. When internal cell pressure exceeds the cell’s safety relief mechanism, rupture or bursting can occur, initiating a cell-to-cell propagation that in turn results in a battery pack fire. By adding a carbon fiber reinforced polymer (CFRP) sleeve to cylindrical battery cells, a sidewall rupture (SWR) can be prevented from occurring or propagating. In initial testing, there were no SWRs of a battery cell using a CFRP sleeve. This result is believed to be due in part to a unique characteristic of CFRP sleeves compared to other materials. Carbon fiber material has a negative coefficient of expansion and accordingly shrinks when heated, while steel and aluminum expand. The shrinking of the CFRP sleeve when heated compresses the cell located within it, significantly aiding in the prevention of SWR. This technology can be implemented into other multi-physics battery safety models to guide the design of the next generation of battery cells and battery packs. This thermal runaway propagation resistant technology has a technology readiness level (TRL) of 6 (System/sub-system model or prototype demonstration in an operational environment) and is now available for patent licensing. Please note that NASA does not manufacture products itself for commercial sale.
Shown: An engineer holds a spent test fixture attached to an 18650 lithium-ion battery cell with an external carbon fiber reinforced polymer sleeve. Notice the sleeve intact, even after a thermal runaway event was induced in the battery cell.
Benefits
  • Prevents cylindrical Li-ion battery cell sidewall ruptures
  • Tempers fire hazard
  • Low-mass alternative to aluminum and steel
  • Not electrically conductive
  • Constructed from easily sourced materials
  • Concept adaptable to other battery models

Applications
  • Spaceflight
  • Aviation
  • Electric bikes
  • Electric cars
  • Laptops
  • Power tools
  • Cameras
Technology Details

Power Generation and Storage
MSC-TOPS-119
MSC-27110-1
Similar Results
bigstock-Lithium-ion-industrial-high-cu-277613656
Ram-Dent Thermal Runaway Triggering Device
The Ram-Dent Thermal Runaway Triggering Device is capable of trig-gering mild short circuits that are similar to internal defects, and more extreme short circuits that are comparable to those initiated by an implanted internal short circuit device – all without having to modify the battery cell in any way. The device imparts a high velocity, low mass blunt impact onto a small surface area of a Li-ion battery cell can wall allowing a small hemispherical dent to form. This impact deforms and tears the internal separator of the battery cell, causing a short circuit, and induces thermal runaway. Several methods for initiating TR on demand currently exist, but they have characteristics and biases that make them more unfavorable for certain testing objectives. Heat-based insult in any form requires additional thermal energy to be applied to the battery cell, potentially distorting the signal-to-noise ratio in FTRC measurement, and increas-ing the severity of failure beyond what is intended. This methodology also requires time to heat the battery cell to critical temperature, and it potentially weakens the battery cell can wall causing abnormal kinetics and rupture. Mechanical insult methodologies, such as crush testing and nail penetration, have unique applications but rely on deformation of the battery cell itself which alters the flow characteristics of internal gases and the material integrity of the battery cell. This technology aims to solve these limitations by implementing a cost-effective method to create a natural short circuit failure in Li-ion batteries that does not alter nominal vent paths and energy yields, potentially yielding the most unbiased calorimeter tallies yet. The Ram-Dent Thermal Runaway Triggering Device is at a technology readiness level (TRL) 4 (component and/or breadboard validation in laboratory environment) and is now available for patent licensing. Please note that NASA does not manufacture products itself for commercial sale.
ThermoArc Facilitates Low-Cost Li-Ion Battery Testing
For years, NASA and the battery industry have been improving passive propagation resistant (PPR) Li-ion battery cell technology by enhancing their material and design choices. These efforts help ensure that a single cell’s TR event does not overheat adjacent cells or the entire battery pack ultimately causing fire or explosion. To improve cell integrity, single cells within battery packs are triggered into TR so that the battery pack can be analyzed for its TR resistance. ThermoArc operates by initiating a plasma arc, capable of delivering thermal energy up to 100W, to a very small (1mm diameter) section of the cell. The extremely localized high heat flux rapidly degrades a small section of the internal cell separator, resulting in a short circuit that leads to TR. This technology comprises several components: a high-turn-ratio step-up transformer capable of producing a minimum of 1,000 V upon the secondary winding, an H-bridge electronic circuit to drive the transformer on the primary side, two tungsten electrodes to deliver the plasma arc, and a power supply unit. ThermoArc applications may exist in any Li-ion battery cell/pack testing application where TR must be induced in an individual cell. Such applications could include testing of PPR battery packs to ensure single cell runaway does not cause catastrophic damage, more general battery destructive testing designed to better understand battery failure states, or other experimental testing. Companies interested in licensing this innovation may include those that manufacture internal short-circuit (ISC) cells or other devices used to induce TR at the individual cell level, battery testing firms, and Li-ion battery manufacturers with a focus on Li-ion battery packs for critical applications. ThermoArc is at a technology readiness level (TRL) 5 (component and/or breadboard validation in laboratory environment) and is now available for patent licensing. Please note that NASA does not manufacture products itself for commercial sale.
Car Charging
Internal Short Circuit Testing Device to Improve Battery Designs
Astronauts' lives depend on the safe performance and reliability of lithium-ion (Li-ion) batteries when they are working and living on the International Space Station. These batteries are used to power everything such as communications systems, laptop computers, and breathing devices. Their reliance on safe use of Li-ion batteries led to the research and development of a new device that can more precisely trigger internal short circuits, predict reactions, and establish safeguards through the design of the battery cells and packs. Commercial applications for this device exist as well, as millions of cell phones, laptops, and electronic drive vehicles use Li-ion batteries every day. In helping manufacturers understand why and how Li-ion batteries overheat, this technology improves testing and quality control processes. The uniqueness of this device can be attributed to its simplicity. In a particular embodiment, it is comprised of a small copper and aluminum disc, a copper puck, polyethylene or polypropylene separator, and a layer of wax as thin as the diameter of one human hair. After implantation of the device in a cell, an internal short circuit is induced by exposing the cell to higher temperatures and melting the wax, which is then wicked away by the separator, cathode, and anode, leaving the remaining metal components to come into contact and induce an internal short. Sensors record the cell's reactions. Testing the battery response to the induced internal short provides a 100% reliable testing method to safely test battery containment designs for thermal runaway. This jointly developed and patented technology is available for your company to license and develop into a commercial product. NASA does not manufacture products for commercial sale.
Li-ion Cell Calorimeter
Li-ion batteries are an integral part of energy storage systems used in NASA's Exploration program, as well as many modern terrestrial industries. Innovators at the NASA Johnson Space Center wanted a better way to measure total and fractional heat response of specific types of Li-ion cells when driven into a thermal runaway condition. They developed a calorimeter with at least two chambers, one for the battery cell under test and at least one other chamber for receiving the thermal runaway ejecta debris. Both are designed to be structurally strong and thermally insulated. When the test cell is intentionally driven into thermal runaway, ejecta explodes into the ejecta chamber and is decelerated and collected. Thermal sensors are strategically placed throughout the chambers to collect thermal data during the test. Customized software analyzes the thermal data and determines key calorimeter parameters with a high degree of accuracy.
Nail Penetration Adapter for Li-Ion Battery Testing
NASA’s pneumatic nail penetration trigger system embodies a fast and consistent nail penetration and retraction tool that tests battery cells within various steel and mylar enclosures. It is operated remotely with electric power and shop air pressure inputs. The trigger system is controlled by a solenoid valve and drives a nail to a set distance at 100 m/s for a precise and repeatable penetration injury to a battery cell. Contributing to the trigger system’s precision and repeatability is the nail penetration adapter that aligns the battery cell test enclosure with the trigger system and guides the nail by its internal barrel. The tip of the adapter threads into a variety of NASA battery cell test enclosures and provides an internal seating stop to ensure a proper targeting depth. On the actuator side of the adapter, two quick-release pins connect the adapter to the actuator mount which is bolted to the actuator subassembly. Removal of these pins readily allow for separation of the nail penetration adapter from the actuator mount and subassembly. During a TR event, the adapter is also designed to prevent flames, sparks, and ejecta from traveling into the actuator subassembly. While the versatile nail penetration adapter was originally configured to interface with NASA’s Fractional Thermal Runaway Calorimeter (FTRC), a blast plate test platform (BPTP), or cell enclosure for passive propagation resistant (PPR) methods, the adapter could be modified for commercial use with other battery testing systems. Companies interested in this technology may include those seeking to improve the safety of Li-ion battery cells and packs along with vertically integrated companies performing in-house TR tests during development of electrified systems like electric vehicles (EVs), electric vertical takeoff and landing (eVTOLs) vehicles, and electronic spacecraft components.
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