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Tailoring Asymmetric Discharge‐Charge Rates and Capacity Limits to Extend Li‐O 2 Battery Cycle Life
Author(s) -
Geaney Hugh,
O'Dwyer Colm
Publication year - 2017
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201600662
Subject(s) - clogging , depth of discharge , battery (electricity) , electrolyte , cathode , materials science , limiting , capacity loss , mechanics , environmental science , analytical chemistry (journal) , electrical engineering , chemistry , electrode , thermodynamics , physics , engineering , chromatography , power (physics) , mechanical engineering , archaeology , history
Widespread issues with the fundamental operation and stability of Li‐O 2 cells impact cycle life and efficiency. While the community continues to research ways of mitigating side reactions and improving stability to realize Li‐O 2 battery prospects, we show that limiting the depth‐of‐discharge while unbalancing discharge/charge rate symmetry can extend Li‐O 2 battery cycle life by ensuring efficient reversible Li 2 O 2 formation, markedly improving cell efficiency. Systematic variation of the discharge/charge currents shows that clogging from discharging the Li‐O 2 cell at high current (250 μA) can be somewhat negated by recharging with a lower applied current (50 μA), with a marked improvement in cycle life achievable. Our measurements determined that specific reduction of the depth of discharge in decrements from equivalent capacities of 1000 mAhg −1 to 50 mAhg −1 under symmetric discharge/charge currents of 50 μA strongly affect the cumulative discharge capacity of each cell. A maximum cumulative discharge capacity occurs at ∼10 % depth of discharge (500 mAhg −1 ) and the cumulative discharge capacity of 39,500 mAhg −1 is significantly greater than that of cells operated at higher and lower depths of discharge. The results emphasize the importance of appropriate discharge/charge rate and depth of discharge selection for other cathode/electrolyte combinations for directly improving the cycle life performance of Li‐O 2 batteries.