Lithium metal anodes are steadily gaining more attention, as their superior specific capacities and low redox voltage can significantly increase the energy density of rechargeable batteries far ...beyond those of current Li‐ion batteries. Nonetheless, the relevant technology is still in a premature research stage mainly due to the uncontrolled growth of Li dendrites that ceaselessly cause unwanted side reactions with electrolyte. In order to circumvent this shortcoming, herein, an ionic liquid additive, namely, 1‐dodecyl‐1‐methylpyrrolidinium (Pyr1(12)+) bis(fluorosulfonyl)imide (FSI−), for conventional electrolyte solutions is reported. The Pyr1(12)+ cation with a long aliphatic chain mitigates dendrite growth via the combined effects of electrostatic shielding and lithiophobicity, whereas the FSI− anion can induce the formation of rigid solid–electrolyte interphase layers. The synergy between the cation and anion significantly improves cycling performance in asymmetric and symmetric control cells and a full cell paired with an LiFePO4 cathode. The present study provides a useful insight into the molecular engineering of electrolyte components by manipulating the charge and structures of the involved molecules.
An ionic liquid additive of 1‐dodecyl‐1‐methylpyrrolidinium (Pyr1(12)+) bis(fluorosulfonyl)imide (FSI‐) is reported for stable cycling of Li metal anodes. The Pyr1(12)+ cation with a long aliphatic chain engages an electrostatic shielding and lithiophobic effect, whereas the FSI‐ anion induces the formation of rigid solid–electrolyte interphase layers. The synergy between both ions suppresses dendrite growth and improves electrochemical performance significantly.
Despite the recent considerable progress, the reversibility and cycle life of silicon anodes in lithium-ion batteries are yet to be improved further to meet the commercial standards. The current ...major industry, instead, adopts silicon monoxide (SiO x , x ≈ 1), as this phase can accommodate the volume change of embedded Si nanodomains via the silicon oxide matrix. However, the poor Coulombic efficiencies (CEs) in the early period of cycling limit the content of SiO x , usually below 10 wt % in a composite electrode with graphite. Here, we introduce a scalable but delicate prelithiation scheme based on electrical shorting with lithium metal foil. The accurate shorting time and voltage monitoring allow a fine-tuning on the degree of prelithiation without lithium plating, to a level that the CEs in the first three cycles reach 94.9%, 95.7%, and 97.2%. The excellent reversibility enables robust full-cell operations in pairing with an emerging nickel-rich layered cathode, LiNi0.8Co0.15Al0.05O2, even at a commercial level of initial areal capacity of 2.4 mAh cm–2, leading to a full cell energy density 1.5-times as high as that of graphite-LiCoO2 counterpart in terms of the active material weight.
Advanced electrode materials have been intensively explored for next‐generation lithium‐ion batteries (LIBs), and great progresses have been achieved for many potential candidates at the lab‐scale. ...To realize the commercialization of these materials, industrially‐viable synthetic approaches are urgently needed. Spray pyrolysis (SP), which is highly scalable and compatible with on‐line continuous production processes, offers great fidelity in synthesis of electrode materials with complex architectures and chemistries. In this review, motivated by the rapid advancement of the given technology in the battery area, we have summarized the recent progress on SP for preparing a great variety of anode and cathode materials of LIBs with emphasis on their unique structures generated by SP and how the structures enhanced the electrochemical performance of various electrode materials. Considering the emerging popularity of sodium‐ion batteries (SIBs), recent electrode materials for SIBs produced by SP will also be discussed. Finally, the powerfulness and limitation along with future research efforts of SP on preparing electrode materials are concisely provided. Given current worldwide interests on LIBs and SIBs, we hope this review will greatly stimulate the collaborative efforts among different communities to optimize existing approaches and to develop innovative processes for preparing electrode materials.
Spray pyrolysis, which is an industrially‐viable synthetic approach, has been widely used to synthesize advanced electrode materials for Li‐ion and Na‐ion batteries. A myriad of electrode materials prepared by spray pyrolysis are summarized and discussed from the perspective of their unique structures generated by spray pyrolysis.
Although the exceptional theoretical specific capacity (1672 mAh g−1) of elemental sulfur makes lithium–sulfur (Li–S) batteries attractive for upcoming rechargeable battery applications (e.g., ...electrical vehicles, drones, unmanned aerial vehicles, etc.), insufficient cycle lives of Li–S cells leave a substantial gap before their wide penetration into commercial markets. Among the key features that affect the cyclability, the shuttling process involving polysulfides (PS) dissolution is most fatal. In an effort to suppress this chronic PS shuttling, herein, a separator coated with poled BaTiO3 or BTO particles is introduced. Permanent dipoles that are formed in the BTO particles upon the application of an electric field can effectively reject PS from passing through the separator via electrostatic repulsion, resulting in significantly improved cyclability, even when a simple mixture of elemental sulfur and conductive carbon is used as a sulfur cathode. The coating of BTO particles also considerably suppresses thermal shrinkage of the poly(ethylene) separator at high temperatures and thus enhances the safety of the cell adopting the given separator. The incorporation of poled particles can be universally applied to a wide range of rechargeable batteries (i.e., metal‐air batteries) that suffer from cross‐contamination of charged species between both electrodes.
Poling for polysulfide rejection: The fatal shuttling process in lithium–sulfur batteries is effectively suppressed by “poled” BaTiO3 or BTO particles coated on a poly(ethylene) separator. The permanent dipoles of poled BTO particles repel polysulfides via electrostatic repulsion. The coating of BTO particles also provides a resistance against thermal shrinkage of the polyethylene separator at high temperature, thus enhancing the safety of the given cell.
This paper shows that for microbial communities, "fences make good neighbors." Communities of soil microorganisms perform critical functions: controlling climate, enhancing crop production, and ...remediation of environmental contamination. Microbial communities in the oral cavity and the gut are of high biomedical interest. Understanding and harnessing the function of these communities is difficult: artificial microbial communities in the laboratory become unstable because of "winner-takes-all" competition among species. We constructed a community of three different species of wild-type soil bacteria with syntrophic interactions using a microfluidic device to control spatial structure and chemical communication. We found that defined microscale spatial structure is both necessary and sufficient for the stable coexistence of interacting bacterial species in the synthetic community. A mathematical model describes how spatial structure can balance the competition and positive interactions within the community, even when the rates of production and consumption of nutrients by species are mismatched, by exploiting nonlinearities of these processes. These findings provide experimental and modeling evidence for a class of communities that require microscale spatial structure for stability, and these results predict that controlling spatial structure may enable harnessing the function of natural and synthetic multispecies communities in the laboratory.
Contrary to early motivation, the majority of aluminium ion batteries developed to date do not utilise multivalent ion storage; rather, these batteries rely on monovalent complex ions for their main ...redox reaction. This limitation is somewhat frustrating because the innate advantages of metallic aluminium such as its low cost and high air stability cannot be fully taken advantage of. Here, we report a tetradiketone macrocycle as an aluminium ion battery cathode material that reversibly reacts with divalent (AlCl
) ions and consequently achieves a high specific capacity of 350 mAh g
along with a lifetime of 8000 cycles. The preferred storage of divalent ions over their competing monovalent counterparts can be explained by the relatively unstable discharge state when using monovalent AlCl
ions, which exert a moderate resonance effect to stabilise the structure. This study opens an avenue to realise truly multivalent aluminium ion batteries based on organic active materials, by tuning the relative stability of discharged states with carrier ions of different valence states.
Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume ...change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the infiltrated CNT network functions as both mechanical support and electrical conductor and Si as a high capacity anode material for Li-ion battery. Such free-standing film has a low sheet resistance of ∼30 Ohm/sq. It shows a high specific charge storage capacity (∼2000 mAh/g) and a good cycling life, superior to pure sputtered-on silicon films with similar thicknesses. Scanning electron micrographs show that Si is still connected by the CNT network even when small breaking or cracks appear in the film after cycling. The film can also “ripple up” to release the strain of a large volume change during lithium intercalation. The conductive composite film can function as both anode active material and current collector. It offers ∼10 times improvement in specific capacity compared with widely used graphite/copper anode sheets.
Sulfide‐based all‐solid‐state batteries (ASSBs) have been featured as promising alternatives to the current lithium‐ion batteries (LIBs) mainly owing to their superior safety. Nevertheless, a ...solution‐based scalable manufacturing scheme has not yet been established because of the incompatible polarity of the binder, solvent, and sulfide electrolyte during slurry preparation. This dilemma is overcome by subjecting the acrylate (co)polymeric binders to protection−deprotection chemistry. Protection by the tert‐butyl group allows for homogeneous dispersion of the binder in the slurry based on a relatively less polar solvent, with subsequent heat‐treatment during the drying process to cleave the tert‐butyl group. This exposes the polar carboxylic acid groups, which are then able to engage in hydrogen bonding with the active cathode material, high‐nickel layered oxide. Deprotection strengthens the electrode adhesion such that the strength equals that of commercial LIB electrodes, and the key electrochemical performance parameters are improved markedly in both half‐cell and full‐cell settings. The present study highlights the potential of sulfide‐based ASSBs for scalable manufacturing and also provides insights that protection−deprotection chemistry can generally be used for various battery cells that suffer from polarity incompatibility among multiple electrode components.
Protection−deprotection chemistry is employed to resolve a dilemma pertaining to polarity compatibility among the binder, solvent, and solid electrolyte for sulfide‐based all‐solid‐state batteries. The polar functional groups of the binder, initially protected by tert‐butyl groups during the slurry mixing stage, are deprotected when the electrode is dried. The polar binder enhances electrode adhesion and electrochemical performance drastically.
Silicon is one of the most attractive anode materials for use in Li-ion batteries due to its ∼10 times higher specific capacity than existing graphite anodes. However, up to 400% volume expansion ...during reaction with Li causes particle pulverization and fracture, which results in rapid capacity fading. Although Si nanomaterials have shown improvements in electrochemical performance, there is limited understanding of how volume expansion takes place. Here, we study the shape and volume changes of crystalline Si nanopillars with different orientations upon first lithiation and discover anomalous behavior. Upon lithiation, the initially circular cross sections of nanopillars with ⟨100⟩, ⟨110⟩, and ⟨111⟩ axial orientations expand into cross, ellipse, and hexagonal shapes, respectively. We explain this by identifying a high-speed lithium ion diffusion channel along the ⟨110⟩ direction, which causes preferential volume expansion along this direction. Surprisingly, the ⟨111⟩ and ⟨100⟩ nanopillars shrink in height after partial lithiation, while ⟨110⟩ nanopillars increase in height. The length contraction is suggested to be due to a collapse of the {111} planes early in the lithiation process. These results give new insight into the Si volume change process and could help in designing better battery anodes.
Na–S batteries are one type of molten salt battery and have been used to support stationary energy storage systems for several decades. Despite their successful applications based on long cycle lives ...and low cost of raw materials, Na–S cells require high temperatures above 300 °C for their operations, limiting their propagation into a wide range of applications. Herein, we demonstrate that Na–S cells with solid state active materials can perform well even at room temperature when sulfur-containing carbon composites generated from a simple thermal reaction were used as sulfur positive electrodes. Furthermore, this structure turned out to be robust during repeated (de)sodiation for ∼500 cycles and enabled extraordinarily high rate performance when one-dimensional morphology is adopted using scalable electrospinning processes. The current study suggests that solid-state Na–S cells with appropriate atomic configurations of sulfur active materials could cover diverse battery applications where cost of raw materials is critical.
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