The effect of mechanical surface modification on the performance of lithium (Li) metal foil electrodes is systematically investigated. The applied micro‐needle surface treatment technique for Li ...metal has various advantages. 1) This economical and efficient technique is able to cover a wide range of surface area with a simple rolling process, which can be easily conducted. 2) This technique achieves improved rate capability and cycling stability, as well as a reduced interfacial resistance. The micro‐needle treatment improves the rate capability by 20% (0.750 mAh at a rate of 7C) and increases the cycling stability by 200% (85% of the initial discharge capacity after 150 cycles) compared to untreated bare Li metal (0.626 mAh at a rate of 7C, 85% of the initial discharge capacity after only 70 cycles). 3) This technique efficiently suppresses Li formation of high surface area Li during the Li deposition process, as preferred sites for controlled Li plating are generated.
The simple, scalable, and cost‐efficient surface treatment technique for Li metal is developed. With a simple rolling process, the micro‐needles create an inverse micro‐needles pattern over wide area of Li metal surface, which remarkably enhances the power capabilities and cycle retention abilities to those of the bare Li metal.
Polydopamine‐treated polyethylene (PE) separators for high‐power lithium ion batteries are developed. A simple dipping process makes the PE surfaces hydrophilic and thus enhances the power ...capabilities remarkably compared to those of the control cases with bare PE separators. The original mechanical and thermal properties of the PE separators are preserved.
Conjugation of mussel‐inspired catechol groups to various polymer backbones results in materials suitable as silicon anode binders. The unique wetness‐resistant adhesion provided by the catechol ...groups allows the silicon nanoparticle electrodes to maintain their structure throughout the repeated volume expansion and shrinkage during lithiation cycling, thus facilitating substantially improved specific capacities and cycle lives of lithium‐ion batteries.
Lithium (Li) metal is one of the most promising candidates for the anode in high‐energy‐density batteries. However, Li dendrite growth induces a significant safety concerns in these batteries. Here, ...a multifunctional separator through coating a thin electronic conductive film on one side of the conventional polymer separator facing the Li anode is proposed for the purpose of Li dendrite suppression and cycling stability improvement. The ultrathin Cu film on one side of the polyethylene support serves as an additional conducting agent to facilitate electrochemical stripping/deposition of Li metal with less accumulation of electrically isolated or “dead” Li. Furthermore, its electrically conductive nature guides the backside plating of Li metal and modulates the Li deposition morphology via dendrite merging. In addition, metallic Cu film coating can also improve thermal stability of the separator and enhance the safety of the batteries. Due to its unique beneficial features, this separator enables stable cycling of Li metal anode with enhanced Coulombic efficiency during extended cycles in Li metal batteries and increases the lifetime of Li metal anode by preventing short‐circuit failures even under extensive Li metal deposition.
Janus‐faced separator design with ultrathin copper (Cu) metal film coating onto one side surface of the conventional polyethylene separator is proposed for lithium (Li) dendrite suppression and cycling stability improvement. Enabling the separator to be electrically and ionically conductive is very effective to facilitate the electrochemical deposition/stripping of Li metal and modulate of the Li metal/electrolyte interface structure.
To elucidate the function of proteorhodopsin in
Candidatus
Puniceispirillum marinum strain IMCC1322, a cultivated representative of SAR116, we produced RNA-seq data under laboratory conditions. We ...examined the transcriptomes of six different cultures, including sets of expression changes under constant dark (DD), constant light (LL), and diel-cycled (LD; 14 h light: 10 h dark) conditions at the exponential and stationary/death phases. Prepared mRNA extracted from the six samples was analyzed on the Solexa Genome Analyzer with 36 cycles. Differentially expressed genes on the IMCC1322 genome were distinguished as four clusters by K-mean clustering and each CDS (n = 2546) was annotated based on the KEGG BRITE hierarchy. Cluster 0 (n = 1573) covered most constitutive genes including proteorhodopsin, retinoids, and glycolysis/TCA cycle. Cluster 1 genes (n = 754) were upregulated in stationary/death phase under constant dark conditions and included genes associated with bacterial defense, membrane transporters, nitrogen metabolism, and senescence signaling. Cluster 2 genes (n = 197) demonstrated upregulation in exponential phase cultures and included genes involved in genes for oxidative phosphorylation, translation factors, and transcription machinery. Cluster 3 (n = 22) contained light-stimulated upregulated genes expressed under stationary/phases. Stringent response genes belonged to cluster 2, but affected genes spanned various cellular processes such as amino acids, nucleotides, translation, transcription, glycolysis, fatty acids, and cell wall components. The coordinated expression of antagonistic stringent genes, including
mazG
,
ppx/gppA
, and
spoT/relA
may provide insight into the controlled cultural response observed between constant light and constant dark conditions in IMCC1322 cultures, regardless of cell numbers and biomass.
To improve the safety of lithium-ion batteries (LIBs), co-polyimide (PI) P84 was introduced as a polymeric binder for Al2O3/polymer composite surface coatings on polypropylene (PP) separators. By ...monitoring the dimensional shrinkage of the PP separators at high temperatures, we verified a synergistic thermal stabilization effect between the Al2O3 ceramic and the PI polymeric binder. Although PI was thermally stable up to 300 °C, a coating consisting solely of PI did not impede the PP separator dimensional changes (−22% at 150 °C). On the other hand, the Al2O3/PI-coated PP separators efficiently impeded the thermal shrinkage (−10% at 150 °C). In contrast, an Al2O3/poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) combination lowered the thermal stability of the PP separators (−33% at 150 °C). As a result, the Al2O3/PI-coated PP separators remarkably suppressed the internal short-circuit of the unit half-cells associated with separator thermal shrinkage (100 min at 160 °C), whereas the PVdF-HFP retained only 40 min under identical conditions. The Al2O3/PI-coated PP separators achieved rate capabilities and cell performances similar to those of the bare PP separators.
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•Co-polyimide (PI) is proposed as a polymeric binder for ceramic composite coatings.•Al2O3/PI coatings synergistically enhance thermal stability of separators.•Al2O3/PI coatings effectively improve the LIB safety by blocking short-circuits.
To develop an environmentally friendly and cost-effective water-based inorganic coating process for hydrophobic, polyolefin-based microporous separators, the effect of surfactants in an aqueous ...inorganic coating solution comprising alumina (Al2O3) on polyethylene (PE)-based microporous separators is investigated. By using a selected surfactant, i.e., disodium laureth sulfosuccinate (DLSS), the aqueous Al2O3 coating solution maintained a dispersed state over time and facilitated the formation of a uniform Al2O3 coating layer on PE separator surfaces. Due to the hydrophilic nature of the Al2O3 coating layers, the as-prepared, ceramic-coated PE separators had better wetting properties, greater electrolyte uptake, and larger ionic conductivities compared to those of the bare PE separators. Furthermore, half cells (LiMn2O4/Li metal) containing Al2O3-coated PE separators showed improved capacity retention over several cycles (93.6% retention after 400 cycles for Al2O3 coated PE separators, compared to 89.2% for bare PE separators operated at C/2) and rate capability compared to those containing bare PE separators. Moreover, because the Al2O3-coated layers are more thermally stable, the coated separators had improved dimensional stability at high temperatures (140 °C).
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•A water-based Al2O3 ceramic coating for polyolefin separators are developed.•The anionic surfactant, i.e., DLSS improves the ceramic coating efficiency.•DLSS containing Al2O3 coating solution maintains a uniform solution over time.•Al2O3 coated separators improve cycle performance and rate capabilities.•Al2O3 coated separators improve dimensional stability at high temperature storage.
Owing to the natural abundance of sodium resources and their low price, next-generation batteries employing an Na metal anode, such as Na–O2 and Na–S systems, have attracted a great deal of interest. ...However, the poor reversibility of an Na metal electrode during repeated electrochemical plating and stripping is a major obstacle to realizing rechargeable sodium metal batteries. It mainly originates from Na dendrite formation and exhaustive electrolyte decomposition due to the high reactivity of Na metal. Herein, we report a free-standing composite protective layer (FCPL) for enhancing the reversibility of an Na metal electrode by mechanically suppressing Na dendritic growth and mitigating the electrolyte decomposition. A systematic variation of the liquid electrolyte uptake of FCPL verifies the existence of a critical shear modulus for suppressing Na dendrite growth, being in good agreement with a linear elastic theory, and emphasizes the importance of the ionic conductivity of FCPL for attaining uniform Na plating and stripping. The Na–Na symmetric cell with an optimized FCPL exhibits a cycle life two times longer than that of a bare Na electrode.
Repressing uncontrolled lithium (Li) dendrite growth is the top priority for enabling the reliable use of Li metal secondary batteries. On the other hand, the technique controlling the metal plating ...behavior during metal plating indeed has been considered very difficult to achieve. For instance, how can one plate metal ions on the favored selected region during plating? The present study describes how to achieve this goal, i.e., dendrite‐free Li deposition, by mechanical surface modification using a simple stamping technique, where finite‐element method simulation using COMSOL Multiphysics was used to design the micro‐patterns of the stamp. After stamping, the transferred micro‐patterns on Li metal anodes suppress dendrite growth during repeated Li deposition/stripping processes and exhibit improved long‐term cycling stability of Li metal anodes. During the repeated Li plating processes, the pattern holes are filled by the liquid‐like and/or granular forms of Li metal without resulting Li dendrite growth. These holes are then reversibly drained during the Li stripping process, reverting to their original dimension. This study investigated the correlation of this unique Li plating/stripping behavior as a function of the current density.
In a collaboration between COMSOL simulation based on a finite element method and post‐mortem analysis, this study visualizes and predicts the Li stripping/deposition behavior of the surface modified Li metal during cycling. Surface‐patterned Li metal having an optimized pattern dimension improves cycle retention abilities and power capabilities, as suppressing Li dendrite growth formation, to those of the bare Li metal.
Li dendrite formation deteriorates cyclability and poses a safety hazard, hindering the widespread use of Li metal as the ultimate anode material for post‐Li‐ion batteries. Hence, the underlying ...reasons of this phenomenon and ways to suppress it have been extensively investigated, which has resulted in the establishment of corresponding theoretical models and their practical applications. Herein, several representative models (e.g., the Chazalviel model) of Li dendrite growth are explained, and the key technologies of structure‐controlled framework and Li metal usage allowing to realize low local current densities and improved electrochemical performance are covered with the practical (dis)advantages due to material characteristics, electrode and cell design, and even manufacturing processes. In particular, the use of Li metal powder and patterned Li metal is discussed in conjunction with corresponding applications (e.g., protection layers, functional additives, and salts in the electrolyte) and advantages.
Considering both high current density and areal capacity for the design of high‐energy‐density secondary batteries, one arrives at the conclusion that Li metal cannot be used itself. So, the effective current density decrease is a top priority task for suppressing Li dendrite growth. In that sense, this review summarizes four strategies in two categories for decreasing the effective current density.
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