Voltage-Induced Bromide Redox Enables Capacity Restoration of Fast-Charging Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 39707696.
- Also identified by DOI 10.1002/adma.202414207.
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Abstract
Fast-charging lithium-ion batteries (LIBs) are essential for electric vehicles (EVs) to compete with conventional gasoline ones in terms of charging viability, yet the aggressive capacity drop in fast-charging scenarios gives rise to concerns regarding durability and sustainability. Herein, it is clarified that for fast-charging batteries, the excessive lithium (Li) plating on graphite anode inevitably brings capacity fading, and the concurrent accumulation of Li<sub>2</sub>O-dominant passivation species that form dead Li is the main reason for their poor rechargeability. To refresh the passivated graphite, a voltage-induced activation mechanism is developed to leverage bromide (Br<sup>-</sup>/Br<sub>3</sub> <sup>-</sup>) redox couple for Li<sub>2</sub>O and isolated Li<sup>0</sup> activation in situ. Along with a tiny amount of lithium bromide (LiBr) added into the electrolyte, the cut-off voltage of activation processes is controlled to initiate and maximize the effectiveness of Br<sup>-</sup>/Br<sub>3</sub> <sup>-</sup> redox couple. The capacity of degraded fast-charging cells can increase from lower than 30 to ≈118 mAh g<sup>-1</sup> before and after the activation, respectively. Notably, the process is not one-off; a subsequent activation is feasible. For the same battery that suffered from another round of fast charging, this design still restores the reversible capacity to ≈100 mAh g<sup>-1</sup>. Such a voltage-mediated mechanism can effectively prolong the service life of practical fast-charging batteries.