Surface modification using heptafluorobutyric acid to produce highly stable Li metal anodes

Abstract

The Li metal is an ideal anode material owing to its high theoretical specific capacity and low electrode potential. However, its high reactivity and dendritic growth in carbonate-based electrolytes limit its application. To address these issues, we propose a novel surface modification technique using heptafluorobutyric acid. In-situ spontaneous reaction between Li and the organic acid generates a lithiophilic interface of lithium heptafluorobutyrate for dendrite-free uniform Li deposition, which significantly improves the cycle stability (Li/Li symmetric cells >1200 h at 1.0 mA cm−2) and Coulombic efficiency (>99.3%) in conventional carbonate-based electrolytes. This lithiophilic interface also enables full batteries to achieve 83.2% capacity retention over 300 cycles under realistic testing condition. Lithium heptafluorobutyrate interface acts as an electrical bridge for uniform lithium-ion flux between Li anode and plating Li, which minimizes the occurrence of tortuous lithium dendrites and lowers interface impedance.

Using a cyclocarbon additive as a cyclone separator to achieve fast lithiation and delithiation without dendrite growth in lithium-ion batteries

“…In recent decades, substantial progress has been made in developing strategies to achieve more uniform Li deposition, including doped and surface functionalized electrodes, 19–21 artificial solid electrolyte interphases (SEIs), 22–24 highly concentrated and solid-state electrolytes 25–27 and separator modification engineering. 28–30 However, these strategies still face a difficult balance between delivery and capacitance.…”

“…28–30 However, these strategies still face a difficult balance between delivery and capacitance. For instance, the use of a heptafluorobutyrate acid–Li SEI 22 and the high-concentration lithium bis(fluorosulfonyl)imide with 1,2-dimethoxyethane electrolyte resulted in a uniform morphology, minimizing the curvature of the Li-deposited microstructure. 25 Although these strategies have shown advantages in achieving more uniform Li deposition during charging, some strategies ignored the losses in the discharging process, including compromising the reversible freedom of both Li + ion diffusion and already formed “dead” Li atoms.…”

Impact of Morphological Dimensions in Carbon‐Based Interlayers on Lithium Metal Anode Stabilization

“…Among these, advancements in battery technology play a pivotal role in propelling society toward a carbon-neutral energy paradigm. [1][2][3] For electric vehicles, one of the key targets is to attain an energy density DOI: 10.1002/aenm.202302565 surpassing 500 Wh kg −1 at the cell level, which is critical for longer driving ranges and more efficient performance. [4][5][6] Currently, Li-ion batteries (LIBs) are widely used, but their specific energy (< 300 Wh kg −1 ) falls short of the target.…”

Gradient Host for Bottom-Up Deposition of Lithium Metal Anode

“…Due to the advantages mentioned above, Li metal batteries (LMBs) are rapidly developing . However, compared with LIBs of the “rocking chair” mechanism to achieve Li + intercalation/deintercalation, LMBs store energy by converting between Li + to Li metal and depositing Li metal on the anode. , Therefore, the volume expansion and the dendrites/dead Li formation of Li metal anode will inevitably occur, resulting in the short lifespan and safety problems of LMBs. − In response to the challenges of volume expansion and Li dendrites, various significant strategies were proposed to improve the electrochemical performance of LMBs, such as electrolyte optimization, − solid-state electrolyte, − interface modification strategies, − etc. Among them, host structure design is a highly straightforward and effective method to optimize Li metal anodes. − …”