Aqueous Zn-ion batteries have attracted increasing research interest; however, the development of these batteries has been hindered by several challenges, including dendrite growth, Zn corrosion, ...cathode material degradation, limited temperature adaptability and electrochemical stability window, which are associated with water activity and the solvation structure of electrolytes. Here we report that water activity is suppressed by increasing the electron density of the water protons through interactions with highly polar dimethylacetamide and trimethyl phosphate molecules. Meanwhile, the Zn corrosion in the hybrid electrolyte is mitigated, and the electrochemical stability window and the operating temperature of the electrolyte are extended. The dimethylacetamide alters the surface energy of Zn, guiding the (002) plane dominated deposition of Zn. Molecular dynamics simulation evidences Zn
ions are solvated with fewer water molecules, resulting in lower lattice strain in the NaV
O
·1.5H
O cathode during the insertion of hydrated Zn
ions, boosting the lifespan of Zn|| NaV
O
·1.5H
O cell to 3000 cycles.
Although lithium–sulfur (Li–S) batteries deliver high specific energy densities, lots of intrinsic and fatal obstacles still restrict their practical application. Electrospun carbon nanofibers (CNFs) ...decorated with ultrafine TiO2 nanoparticles (CNF-T) were prepared and used as a multifunctional interlayer to suppress the volume expansion and shuttle effect of Li–S battery. With this strategy, the CNF network with abundant space and superior conductivity can accommodate and recycle the dissolved polysulfides for the bare sulfur cathode. Meanwhile, the ultrafine TiO2 nanoparticles on CNFs work as anchoring points to capture the polysulfides with the strong interaction, making the battery perform with remarkable and stable electrochemical properties. As a result, the Li–S battery with the CNF-T interlayer delivers an initial reversible capacity of 935 mA h g–1 at 1 C with a capacity retention of 74.2% after 500 cycles. It is believed that this simple, low-cost and scalable method will definitely bring a novel perspective on the practical utilization of Li–S batteries.
The development of reliable and safe high‐energy‐density lithium‐ion batteries is hindered by the structural instability of cathode materials during cycling, arising as a result of detrimental phase ...transformations occurring at high operating voltages alongside the loss of active materials induced by transition metal dissolution. Originating from the fundamental structure/function relation of battery materials, the authors purposefully perform crystallographic‐site‐specific structural engineering on electrode material structure, using the high‐voltage LiNi0.5Mn1.5O4 (LNMO) cathode as a representative, which directly addresses the root source of structural instability of the Fd3¯m structure. By employing Sb as a dopant to modify the specific issue‐involved 16c and 16d sites simultaneously, the authors successfully transform the detrimental two‐phase reaction occurring at high‐voltage into a preferential solid‐solution reaction and significantly suppress the loss of Mn from the LNMO structure. The modified LNMO material delivers an impressive 99% of its theoretical specific capacity at 1 C, and maintains 87.6% and 72.4% of initial capacity after 1500 and 3000 cycles, respectively. The issue‐tracing site‐specific structural tailoring demonstrated for this material will facilitate the rapid development of high‐energy‐density materials for lithium‐ion batteries.
Crystallographic‐site‐specific structural engineering is performed on the cathode material structure for lithium‐ion batteries, aiming at the root causes of the instability based on the fundamental structure/function relationship. The high‐voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode with Fd3¯m space group symmetry is employed as a representative, of which two issue‐involved crystallographic sites are directly and simultaneously addressed, contributing to an extraordinarily excellent battery performance.
Porous Si can be synthesized from diverse silica (SiO
2
) via magnesiothermic reduction technology and widely employed as potential anode material in lithium ion batteries. However, concerns ...regarding the influence of residual silicon oxide (SiO
x
) component on resulted Si anode after reduction are still lacked. In this work, we intentionally fabricate a cauliflower-like silicon/silicon oxide (CF-Si/SiO
x
) particles from highly porous SiO
2
spheres through insufficient magnesiothermic reduction, where residual SiO
x
component and internal space play an important role in preventing the structural deformation of secondary bulk and restraining the expansion of Si phase. Moreover, the hierarchically structured CF-Si/SiO
x
exhibits uniformly-dispersed channels, which can improve ion transport and accommodate large volume expansion, simultaneously. As a result, the CF-Si/SiO
x
-700 anode shows excellent electrochemical performance with a specific capacity of ~1,400 mA·h·g
−1
and a capacity retention of 98% after 100 cycles at the current of 0.2 A·g
−1
.
Abstract Sluggish kinetics of the CO 2 reduction/evolution reactions lead to the accumulation of Li 2 CO 3 residuals and thus possible catalyst deactivation, which hinders the long-term cycling ...stability of Li-CO 2 batteries. Apart from catalyst design, constructing a fluorinated solid-electrolyte interphase is a conventional strategy to minimize parasitic reactions and prolong cycle life. However, the catalytic effects of solid-electrolyte interphase components have been overlooked and remain unclear. Herein, we systematically regulate the compositions of solid-electrolyte interphase via tuning electrolyte solvation structures, anion coordination, and binding free energy between Li ion and anion. The cells exhibit distinct improvement in cycling performance with increasing content of C-N species in solid-electrolyte interphase layers. The enhancement originates from a catalytic effect towards accelerating the Li 2 CO 3 formation/decomposition kinetics. Theoretical analysis reveals that C-N species provide strong adsorption sites and promote charge transfer from interface to *CO 2 2− during discharge, and from Li 2 CO 3 to C-N species during charge, thereby building a bidirectional fast-reacting bridge for CO 2 reduction/evolution reactions. This finding enables us to design a C-N rich solid-electrolyte interphase via dual-salt electrolytes, improving cycle life of Li-CO 2 batteries to twice that using traditional electrolytes. Our work provides an insight into interfacial design by tuning of catalytic properties towards CO 2 reduction/evolution reactions.
Rechargeable sodium metal batteries (SMBs) have emerged as promising alternatives to commercial Li‐ion batteries because of the natural abundance and low cost of sodium resources. However, the ...overuse of metallic sodium in conventional SMBs limits their energy densities and leads to severe safety concerns. Herein, we propose a sodium‐free‐anode SMB (SFA‐SMB) configuration consisting of a sodium‐rich Na superionic conductor‐structured cathode and a bare Al/C current collector to address the above challenges. Sodiated Na3V2(PO4)3 in the form of Na5V2(PO4)3 was investigated as a cathode to provide a stable and controllable sodium source in the SFA‐SMB. It provides not only remarkable Coulombic efficiencies of Na plating/stripping cycles but also a highly reversible three‐electron redox reaction within 1.0–3.8 V versus Na/Na+ confirmed by structural/electrochemical measurements. Consequently, an ultrahigh energy density of 400 Wh kg−1 was achieved for the SFA‐SMB with fast Na storage kinetics and impressive capacity retention of 93% after 130 cycles. A narrowed voltage window (3.0–3.8 V vs. Na/Na+) further increased the lifespan to over 300 cycles with a high retained specific energy of 320 Wh kg−1. Therefore, the proposed SFA‐SMB configuration opens a new avenue for fabricating next‐generation batteries with high energy densities and long lifetimes.
Sodium‐rich Na superionic conductor‐structured cathodes are proposed to increase the energy density and lifespan of sodium‐free‐anode sodium metal batteries (SFA‐SMBs). The prestored Na in Na5V2(PO4)3 provides not only remarkable Na plating/stripping efficiencies but also a highly reversible three‐electron redox reaction, resulting in an ultrahigh energy density of 400 Wh kg−1 and superior cyclic stability.
High-performance lithium-ion batteries (LIB) are important in powering emerging technologies. Cathodes are regarded as the bottleneck of increasing battery energy density, among which layered oxides ...are the most promising candidates for LIB. However, a limitation with layered oxides cathodes is the transition metal and Li site mixing, which significantly impacts battery capacity and cycling stability. Despite recent research on Li/Ni mixing, there is a lack of comprehensive understanding of the origin of cation mixing between the transition metal and Li; therefore, practical means to address it. Here, a critical review of cation mixing in layered cathodes has been provided, emphasising the understanding of cation mixing mechanisms and their impact on cathode material design. We list and compare advanced characterisation techniques to detect cation mixing in the material structure; examine methods to regulate the degree of cation mixing in layered oxides to boost battery capacity and cycling performance, and critically assess how these can be applied practically. An appraisal of future research directions, including superexchange interaction to stabilise structures and boost capacity retention has also been concluded. Findings will be of immediate benefit in the design of layered cathodes for high-performance rechargeable LIB and, therefore, of interest to researchers and manufacturers.
Growth in intermittent renewable sources including solar and wind has sparked increasing interest in electrical energy storage. Grid‐scale energy storage integrated with renewable sources has ...significant advantages in energy regulation and grid security. Aqueous zinc‐ion batteries (AZIBs) have emerged as a practically attractive option for electrical storage because of environmentally benign aqueous‐based electrolytes, high theoretical capacity of Zn anode, and significant global reserves of Zn. However, application of AZIBs at the grid‐scale is restricted by drawbacks in cathode material(s). Herein, a comprehensive summary of the features and storage mechanisms of the latest cathode materials is provided. The fundamental problems and corresponding in‐depth causes for cathode materials is critically reviewed. It is also assess practical challenges, appraise their translation to commerce and industry, and systematically summarize and discuss the potential solutions reported in recent works. It is established necessary design strategies for Zn anodes and electrolytes that are matched with cathode materials for commercializing AZIBs. Finally, it is concluded with a perspective on the practical prospects for advancing the development of future AZIBs. Findings will be of interest and benefit to a range of researchers and manufacturers in the design and application of AZIBs for grid‐scale energy storage.
Application of aqueous zinc‐ion batteries (AZIBs) at the grid‐scale is restricted by drawbacks in cathode materials). To advance the commercialization of AZIBs, this review critically summarizes fundamentally practical problems and corresponding potential solutions of cathodes reported in recent works. Necessary design strategies for Zn anodes and electrolytes, and perspectives on practical prospects of AZIBs are provided for future improvements.
The fabrication of highly durable, flexible, all‐solid‐state supercapacitors (ASCs) remains challenging because of the unavoidable mechanical stress that such devices are subjected to in wearable ...applications. Natural/artificial fiber textiles are regarded as prospective materials for flexible ASCs due to their outstanding physicochemical properties. Here, a high‐performance ASC is designed by employing graphene‐encapsulated polyester fiber loaded with polyaniline as the flexible electrodes and bacterial cellulose (BC) nanofiber‐reinforced polyacrylamide as the hydrogel electrolyte. The ASC combines the textile electrode capable of arbitrary deformation with the BC‐reinforced hydrogel with high ionic conductivity (125 mS cm−1), high tensile strength (330 kPa), and superelasticity (stretchability up to ≈1300%), giving rise to a device with high stability/compatibility between the electrodes and electrolyte that is compliant with flexible electronics. As a result, this ASC delivers high areal capacitance of 564 mF cm−2, excellent rate capability, good energy/power densities, and more importantly, superior mechanical properties without significant capacitance degradation after repeated bending, confirming the functionality of the ASC under mechanical deformation. This work demonstrates an effective design for a sufficiently tough energy storage device, which shows great potential in truly wearable applications.
A flexible supercapacitor with high stability/compatibility is developed by employing graphene‐encapsulated polyester fiber loaded polyaniline as the flexible electrodes, bacterial cellulose nanofiber‐reinforced polyacrylamide as the hydrogel electrolyte. The device delivers high electrochemical performance under mechanical deformation and confirms the functionality for wearable energy storages. This work demonstrates an effective design for durable flexible supercapacitors.
Lithium–sulfur (Li–S) batteries are seriously restrained by the shuttling effect of intermediary products and their further reduction on the anode surface. Considerable researches have been devoted ...to overcoming these issues by introducing carbon-based materials as the sulfur host or interlayer in the Li–S systems. Herein, we constructed a multifunctional interlayer on a separator by inserting Fe3O4 nanoparticles (NPs) in a porous graphene (PG) film to immobilize polysulfides effectively. The porous structure of graphene was optimized by controlling the oxidation conditions for facilitating ion transfer. The polar Fe3O4 NPs were employed to trap sulfur species via strong chemical interaction. By exploiting the PG-Fe3O4 interlayer with optimal porous structure and component, the Li–S battery delivered a superior cycling performance and rate capability. The reversible discharge capacity could be maintained at 732 mAh g–1 after 500 cycles and 356 mAh g–1 after total 2000 cycles at 1 C with a final capacity retention of 49%. Moreover, a capacity of 589 mAh g–1 could also be maintained even at 2 C rate.
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