Advances in Repairing Electric Vehicle (EV) Batteries

Battery pack case for electric vehicles that allows easier and cheaper replacement of worn or damaged parts. The case uses a bolt and nut coupling instead of welding. The bolt attaches to the vehicle frame, with a first nut tightening onto it and a second nut tightening onto the first nut. This provides a secure connection without welding. When the battery pack is repeatedly attached and detached, only the nuts may wear out or get damaged. By avoiding welding, these nuts can be easily replaced instead of the entire frame, reducing maintenance cost.

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An efficient way to refurbish, repair or test used battery packs from electric vehicles. The method involves removing the battery pack from the vehicle, testing and identifying any bad or failing batteries, and replacing them with similar batteries that have compatible electrical characteristics. By replacing only the specific failing batteries instead of the entire pack, the cost and waste associated with battery pack replacements can be reduced.

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Method to accurately identify low voltage defects in lithium secondary batteries after formation by accounting for temperature exposure during transport and storage. The method involves measuring the primary voltage of a battery after formation, then measuring the secondary voltage after transport. The secondary voltage is corrected based on the temperature exposure during transport. If the corrected secondary voltage is significantly lower than the primary voltage, it indicates a low voltage defect. This prevents false positives due to normal batteries experiencing higher voltage drops at higher temperatures.

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Recovering the capacity of lithium batteries that have degenerated during cycling by heat treatment. The method involves subjecting a lithium battery cell with at least 5% capacity loss to a high temperature treatment of 60-100°C for 1-6 hours in a fully discharged state. This reversibly activates lithium plating on the negative electrode to prevent further capacity loss. The heat treatment should be outside the range where it affects other battery components.

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Balancing charging and discharging individual batteries in an electric vehicle's battery pack to improve pack performance and lifespan. The balancing is done by selectively charging or discharging cells to match the charge levels of other cells. This prevents overcharging of some cells while undercharging others, which can degrade pack performance. The balancing is done using a maintenance device that can independently charge/discharge cells in the pack.

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Modular battery system for electric vehicles that allows easy swapping of batteries to simplify service and repair. The battery system uses a carrier frame that holds separate component carriers for the electronics and battery modules. These carriers can be individually attached and detached from the frame. The frame provides power, signal, and coolant connections to the component carriers. This allows swapping out just the electronics or battery modules as needed without removing the entire battery. The carriers have integrated coolant ducts for cooling.

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Processes for improving the performance and cycle life of lithium-ion batteries. The processes involve holding the battery at a sub-discharge voltage below its normal discharge cutoff for a recovery time. This step recaptures lost capacity and reduces impedance compared to an untreated battery. The recovery time can be hours or days at voltages like 0V. Repeated recovery steps during cycling further improves performance. This allows recovering lost capacity without over-discharging the battery, reducing cold temperature impedance, and increasing cold cranking amps. The recovery step involves holding the battery at a sub-discharge voltage for a recovery time sufficient to show increased capacity or reduced impedance. The sub-discharge voltage is less than the normal cutoff. The recovery time can be from 1 hour to 120 hours.

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Method to rejuvenate degraded lithium-ion batteries by treating the electrodes inside the pouch with a solvent to remove degradation products like lithium fluoride from the solid electrolyte interphase (SEI) layer. This involves introducing a solvent into the battery pouch, heating it, and then removing most of the solvent before filling the pouch with fresh electrolyte. The solvent treatment helps dissolve and remove some of the SEI layer, allowing recovery of battery performance when recharged.

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Rejuvenating degraded lithium-ion batteries by dissolving and removing degraded electrolyte layers to restore performance. The process involves opening the battery pouch in a controlled environment, dissolving low-conductivity electrolyte layers using a solvent, removing the solvent and degraded electrolyte, replacing with fresh electrolyte, and sealing the pouch. This aims to reverse the effects of SEI layer thickening and electrolyte decomposition that contribute to capacity loss in aged batteries.

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A method for identifying defective electrodes during lithium-ion polymer battery assembly to prevent using faulty electrodes in batteries and reduce waste. The method involves monitoring voltage during stacking, detecting voltage drops, identifying the faulty electrode causing the drop, removing it, and continuing assembly. This allows separating and discarding defective electrodes without throwing away good ones.

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