Unlocking the Na-Storage Behavior in Hard Carbon Anode by Mass Spectrometry.
basic_science · Level V
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- Record sourced from PubMed, PMID 39087826.
- Also identified by DOI 10.1021/acs.nanolett.4c01620.
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Abstract
Hard carbon (HC) is a promising anode candidate for Na-ion batteries (NIBs) because of its excellent Na-storage performance, abundance, and low cost. However, a precise understanding of its Na-storage behavior remains elusive. Herein, based on the D<sub>2</sub>O/H<sub>2</sub>SO<sub>4</sub>-based TMS results collected on charged/discharged state HC electrodes, detailed Na-storage mechanisms (the Na-storage states and active sites in different voltage regions), specific SEI dynamic evolution process (formation, rupture, regeneration and loss), and irreversible capacity contribution (dead Na<sup>0</sup>, NaH, etc.) were elucidated. Moreover, by employing the online electrochemical mass spectrometry (OEMS) to monitor the gassing behavior of HC-Na half-cell during the overdischarging process, a surprising rehydrogen evolution reaction (re-HER) process at around 0.02 V vs Na<sup>+</sup>/Na was identified, indicating the occurrence of Na-plating above 0 V vs Na<sup>+</sup>/Na. Additionally, the typical fluorine ethylene carbonate (FEC) additive was demonstrated to reduce the accumulation of dead Na<sup>0</sup> and inhibit the re-HER process triggered by plated Na.