Safety Materials in EV Batteries for Enhanced Protection

A secondary battery with improved safety and widened hot box temperature window. The battery has a separator with organic coatings on the sides facing the electrodes. The coating on the positive side contains a polymer with a melting point of 60-100°C. This low-melting polymer provides good adhesion at normal temperatures but separates at high temperatures to prevent heat accumulation and thermal runaway. It widens the safe operating temperature range without affecting cycle performance.

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A battery cell design to prevent thermal runaway propagation in lithium-ion batteries. The cell has an electrode stack with separators made from materials like polypropylene and polyethylene. To prevent thermal runaway between electrodes, the separator material can contain powdered flame retardant. Additionally, the anode can be coated with a carbon layer containing aluminum oxide particles to support lithium storage and prevent dendrite growth. These modifications aim to prevent thermal runaway spreading from one electrode to the next in the event of an overheating or failure condition.

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Lithium-ion battery separator with improved safety and electrochemical performance. The separator is a single-layer film made of a high molecular polymer and a nitrogen-phosphorus flame retardant. The separator has excellent heat stability, flame retardance, and electrolyte wettability. The flame retardant content is 10-50 wt% of the separator. The separator can be prepared by dissolving the polymer, flame retardant, and pore former in a solvent, casting, and drying.

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Separators for lithium-ion batteries with fire suppression capability to prevent thermal runaway propagation. The separator has a microporous polymer layer sandwiched between the battery electrodes. Crosslinked cyclophosphazene particles are deposited on one or both sides of the microporous layer. These particles quench and inhibit combustion chain reactions when exposed to high temperatures.

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A separator for secondary batteries that reduces the risk of thermal runaway and explosion. The separator has a base film coated with a flame-retardant layer. The flame-retardant layer contains capsules with a core of flame retardant material like phosphorus compounds encapsulated in PMMA shells. The PMMA shell provides adhesion and prevents direct contact between the flame retardant and electrolyte during normal battery operation. If thermal runaway occurs, the PMMA shell breaks releasing the flame retardant to capture combustion free radicals and prevent further spread of fire.

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Flame-retardant diaphragm for lithium batteries, solid electrolyte interface layer, and battery to improve safety and performance of lithium metal batteries. The diaphragm has a flame retardant layer containing aluminum diethylphosphinate. During charging/discharging, it forms a solid electrolyte interface layer on the negative electrode that contains aluminum-containing inorganic salts, phosphorus-containing inorganic salts, and lithium aluminum alloy. This layer passivates the reactive lithium metal, prevents dendrite growth, and enhances cycle life compared to organic electrolytes. The aluminum phosphinate diaphragm also acts as a flame retardant to mitigate lithium metal battery fires.

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Separator for lithium-ion batteries with fire suppression capability to prevent battery cell thermal runaway and propagation. The separator has a microporous layer sandwiched between the electrodes, with fire suppression layers on one or both sides. The fire suppression layers contain a ceramic with interconnected pores filled with a cyclophosphazene compound. The cyclophosphazene quenches and inhibits combustion chain reactions when exposed to high temperatures, preventing thermal runaway propagation in case of battery cell failures.

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Secondary battery with improved thermal safety by using a separator with a coating on the base film that melts at high temperatures to seal the separator pores and prevent thermal runaway. The coating density, base film porosity, and thickness are controlled to balance pore closing at high temperatures with normal battery operation. The coating melts at 90°C or above, has a density of 0.9-1.05 g/cm3, the base film has 20-50% porosity, and thickness of 3-10 μm. This allows the coating to seal the base film pores at high temperatures to prevent thermal runaway.

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A flame-resistant polymer composite separator for lithium batteries that prevents dendrite formation and reactions between lithium metal and the electrolyte. The separator has a porous layer of a flame-resistant polymer with pores filled by a second polymer. The first polymer has high ionic conductivity and flame resistance. The second polymer fills the pores and provides electrical continuity. This separator eliminates dendrite growth by allowing lithium ion transport through the porous layer and prevents electrolyte reactions with lithium metal by isolating the metal surface.

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Heat-resistant flame-retardant composite battery separator that improves safety and cycle life of lithium-ion batteries. The separator has a base microporous polyolefin layer, inorganic particles, a binder, and a flame retardant. The inorganic particles and binder coat the base layer. The inorganic particles improve thermal stability and flame resistance. The binder adheres the particles to the base. The composite separator provides better heat resistance, flame retardance, mechanical strength, and electrolyte retention compared to conventional separators.

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Battery separator with optimized coating layers to improve hot box test passing rate and normal battery performance. The separator has a first coating layer with two polymers of different melting points. The lower melting point polymer disperses around the higher melting point polymer to prevent pore blocking during battery preparation and usage. This balances cohesion for hot box containment with gas permeability. The adhesion between coating layers is adjusted to open interfaces during heat generation while preventing deformation during charge/discharge. The coating thickness and particle sizes are optimized for adhesion, gas permeability, and cohesion. The weight ratios of the polymers balance hot box performance with normal battery adhesion.

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High-safety heat-absorbing flame-retardant diaphragm for lithium ion batteries that can balance safety and electrochemical performance. The diaphragm is made by coaxial electrospinning of polymer fibers with a core-shell structure. The core has a heat-absorbing flame-retardant layer containing a heat absorber, flame retardant, drying agent, and low-melting-point polymers. The outer protective layer is made of high-melting-point polymers. This design allows the diaphragm to absorb heat and prevent flaming when the battery overheats. The inner heat-absorbing layer uses materials like basic carbonates that absorb heat and release water. This prevents battery degradation from excessive moisture. The outer protective layer stops combustion by melting at high temperatures.

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A separator for lithium-ion batteries that provides high capacity and safety. The separator has a unique composition and structure to balance capacity improvement with thermal and mechanical stability. It uses a polyolefin-based microporous substrate coated with a heat-resistant layer containing inorganic particles and a binder. The total separator thickness is 10-40 µm. The heat-resistant layer thickness is 90% of the substrate thickness. This design provides heat resistance, mechanical strength, and capacity retention compared to conventional separators.

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A heat-resistant battery separator with improved integrity and shutdown capability for lithium-ion batteries. The separator has three layers: two microporous layers sandwiched between a heat-resistant layer. This configuration provides separation and integrity at high temperatures during thermal runaway. The heat-resistant layer can be made of a high melt integrity material like polyaramid, polyimide, or polyamideimide. The microporous layers can have functional groups on their surfaces that increase adhesion to the heat-resistant layer. This prevents curling and delamination during thermal runaway.

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Flame-retardant composite separator for lithium-ion batteries that reduces the risk of thermal runaway. The separator has a base film and a coating containing low-melting-point polymers, nanofiber flame retardants, paraffin microspheres, thickening agent, and binder. The low-melting-point polymers lower the closed pore temperature to prevent ion transmission and reaction escalation. The nanofiber flame retardants release after melting to reduce temperature rise. The paraffin microspheres have a lower melting point than the base film, delaying closed pore formation. The thickening agent prevents separation. The binder holds the coating together.

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Lithium ion battery diaphragm with improved short circuit prevention and fire resistance compared to conventional diaphragms. The diaphragm has a base film sandwiched between reinforcing structures on both sides. The reinforcing structures include ceramic coatings, fire retardant layers, and air bags filled with flame retardant foaming agents. The reinforced diaphragm prevents electrode particle penetration through micropores while also blocking short circuits. The fire retardant layers and foaming agents prevent flame propagation in case of thermal runaway.

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Battery diaphragm with improved flame retardant properties to enhance battery safety. The diaphragm has multiple layers stacked between the positive and negative electrodes. The topmost layer is a fire-retardant layer made of nano ceramic powder. This layer melts at high temperatures and seals off the diaphragm to prevent ion conduction and short circuits. Below it are layers of regular diaphragm material to allow ion transfer. The bottom layer is the electrode. This multi-layer configuration provides ion conduction, separates the electrodes, and adds fire retardancy.

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Flame-retardant diaphragm for lithium-ion batteries that reduces ignition and explosion risk during thermal runaway. The diaphragm contains an inorganic flame retardant called ammonium aluminum carbonate (AAC) that coats the separator between the battery's positive and negative electrodes. The AAC prevents ignition and explosion when the battery overheats by forming a protective barrier that absorbs heat and inhibits combustion reactions. This improves battery safety without complex preparation or material substitutions.

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Flame-retardant composite diaphragm for lithium-ion batteries that improves safety without degrading performance. The diaphragm has a flame-retardant coating with a double-layer microcapsule. The inner layer has a flame retardant and melts at higher temps. The outer layer melts at lower temps to seal the diaphragm. This prevents battery shorting at low temps, then releases flame retardant at high temps to prevent thermal runaway. The double-layer microcapsule provides dual effects of closed pores and flame retardance without adverse battery impacts.

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Multi-layer composite functional separator for lithium-ion batteries with improved safety and thermal stability compared to conventional separators. The separator has four layers: a base layer, an insulating layer, an expanding layer, and a shrinkage layer. The layers are stacked in a specific order. The base layer provides mechanical support. The insulating layer prevents short circuits. The expanding layer has microspheres that expand with temperature to reduce current density. The shrinkage layer shrinks less than conventional separators to prevent contact during thermal runaway. The multi-layer structure improves safety and thermal stability of lithium-ion batteries.

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