Simple Construction of Multistage Stable Silicon–Graphite Hybrid Granules for Lithium-Ion Batteries

Because of its high specific capacity, the silicon–graphite composite (SGC) is regarded as a promising anode for new-generation lithium-ion batteries. However, the frequently employed two-section preparation process, including the modification of silicon seed and followed mixture with graphite, cannot ensure the uniform dispersion of silicon in the graphite matrix, resulting in a stress concentration of aggregated silicon domains and cracks in composite electrodes during cycling. Herein, inspired by powder engineering, the two independent sections are integrated to construct multistage stable silicon–graphite hybrid granules (SGHGs) through wet granulation and carbonization. This method assembles silicon nanoparticles (Si NPs) and graphite and improves compatibility between them, addressing the issue of severe stress concentration caused by uncombined residue of Si NPs. The optimal SGHG prepared with 20% pitch content exhibits a highly reversible specific capacity of 560.0 mAh g⁻¹ at a current density of 200 mA g⁻¹ and a considerable stability retention of 86.1% after 1000 cycles at 1 A g⁻¹. Moreover, as a practical application, the full cell delivers an outstanding capacity retention of 85.7% after 400 cycles at 2 C. The multistage stable structure constructed by simple wet granulation and carbonization provides theoretical guidance for the preparation of commercial SGC anodes.     

Tuning the Anode–Electrolyte Interface Chemistry for Garnet-Based Solid-State Li Metal Batteries

Lithium (Li) metal is a promising candidate as the anode for high-energy-density solid-state batteries. However, interface issues, including large interfacial resistance and the generation of Li dendrites, have always frustrated the attempt to commercialize solid-state Li metal batteries (SSLBs). Here, it is reported that infusing garnet-type solid electrolytes (GSEs) with the air-stable electrolyte Li₃PO₄ (LPO) dramatically reduces the interfacial resistance to ≈1 Ω cm² and achieves a high critical current density of 2.2 mA cm⁻² under ambient conditions due to the enhanced interfacial stability to the Li metal anode. The coated and infused LPO electrolytes not only improve the mechanical strength and Li-ion conductivity of the grain boundaries, but also form a stable Li-ion conductive but electron-insulating LPO-derived solid-electrolyte interphase between the Li metal and the GSE. Consequently, the growth of Li dendrites is eliminated and the direct reduction of the GSE by Li metal over a long cycle life is prevented. This interface engineering approach together with grain-boundary modification on GSEs represents a promising strategy to revolutionize the anode–electrolyte interface chemistry for SSLBs and provides a new design strategy for other types of solid-state batteries.     

New High Donor Electrolyte for Lithium–Sulfur Batteries

The unparalleled theoretical specific energy of lithium–sulfur (Li–S) batteries has attracted considerable research interest from within the battery community. However, most of the long cycling results attained thus far relies on using a large amount of electrolyte in the cell, which adversely affects the specific energy of Li–S batteries. This shortcoming originates from the low solubility of polysulfides in the electrolyte. Here, 1,3-dimethyl-2-imidazolidinone (DMI) is reported as a new high donor electrolyte for Li–S batteries. The high solubility of polysulfides in DMI and its activation of a new reaction route, which engages the sulfur radical (S₃^•−), enables the efficient utilization of sulfur as reflected in the specific capacity of 1595 mAh g⁻¹ under lean electrolyte conditions of 5 μL_electrolyte mg_sulfur⁻¹. Moreover, the addition of LiNO₃ stabilizes the lithium metal interface, thereby elevating the cycling performance to one of the highest known for high donor electrolytes in Li–S cells. These engineered high donor electrolytes are expected to advance Li–S batteries to cover a wide range of practical applications, particularly by incorporating established strategies to realize the reversibility of lithium metal electrodes.     

Stable LiF-Rich Electrode–Electrolyte Interface toward High-Voltage and High-Energy-Density Lithium Metal Solid Batteries

Lithium-rich layered oxide (LRLO) materials have attracted significant attention due to their high specific capacity, low cost, and environmental friendliness. However, owing to its unique capacity activation mechanism, the release of lattice oxygen during the first charge process leads to a series of problems, such as severe voltage decay, poor cycle stability, and poor rate performance. Herein, a fluorinated quasi-solid-state electrolyte (QSSE) via a simple thermal polymerization method toward lithium metal batteries with LRLO materials is reported. The well-designed QSSE exhibits an ionic conductivity of 6.4 × 10⁻⁴ S cm⁻¹ at 30 °C and a wide electrochemical stable window up to 5.6 V. Most importantly, XPS spectra demonstrate the generation of a LiF-rich electrode–electrolyte interface (EEI), where the in situ generated LiF provides strong protection against the structural degradation of LRLO materials and directs the uniform plating/stripping behaviors of lithium-ions to inhibit the formation of lithium dendrites. As a result, LRLO/QSSE/Li batteries exhibit excellent rate performance and demonstrate a large initial capacity for 209.7 mA h g⁻¹ with a capacity retention of 80.8% after 200 cycles at 0.5C. This work provides a new insight for the LiF-rich EEI design of safe, high-performance quasi-solid-state lithium metal batteries.     

Calendering-Compatible Macroporous Architecture for Silicon–Graphite Composite toward High-Energy Lithium-Ion Batteries

Porous strategies based on nanoengineering successfully mitigate several problems related to volume expansion of alloying anodes. However, practical application of porous alloying anodes is challenging because of limitations such as calendering incompatibility, low mass loading, and excessive usage of nonactive materials, all of which cause a lower volumetric energy density in comparison with conventional graphite anodes. In particular, during calendering, porous structures in alloying-based composites easily collapse under high pressure, attenuating the porous characteristics. Herein, this work proposes a calendering-compatible macroporous architecture for a Si–graphite anode to maximize the volumetric energy density. The anode is composed of an elastic outermost carbon covering, a nonfilling porous structure, and a graphite core. Owing to the lubricative properties of the elastic carbon covering, the macroporous structure coated by the brittle Si nanolayer can withstand high pressure and maintain its porous architecture during electrode calendering. Scalable methods using mechanical agitation and chemical vapor deposition are adopted. The as-prepared composite exhibits excellent electrochemical stability of > 3.6 mAh cm⁻², with mitigated electrode expansion. Furthermore, full-cell evaluation shows that the composite achieves higher energy density (932 Wh L⁻¹) and higher specific energy (333 Wh kg⁻¹) with stable cycling than has been reported in previous studies.     

Electron-State Confinement of Polysulfides for Highly Stable Sodium–Sulfur Batteries

Confinement of polysulfides in sulfur cathodes is pivotal for eliminating the “shuttle effect” in metal–sulfur batteries, which represent promising solutions for large-scale and sustainable energy storage. However, mechanistic exploration and in-depth understanding for the confinement of polysulfides remain limited. Consequently, it is a critical challenge to achieve highly stable metal–sulfur batteries. Here, based on a 2D metal–organic framework (2D MOF), a new mechanism to realize effective confinement of polysulfides is proposed. A combination of in situ synchrotron X-ray diffraction, electrochemical measurements, and theoretical computations reveal that the dynamic electron states of the Ni centers in the 2D MOF enable the interaction between polysulfides and the MOF in the discharge/charge process to be tuned, resulting in both strong adsorption and fast conversion kinetics of polysulfides. The resultant room-temperature sodium–sulfur batteries are amongst the most stable reported so far, thus demonstrating that the new mechanism opens a promising avenue for the development of high-performance metal–sulfur batteries.     

A Rational Reconfiguration of Electrolyte for High-Energy and Long-Life Lithium–Chalcogen Batteries

Lithium–chalcogen batteries are an appealing choice for high-energy-storage technology. However, the traditional battery that employs liquid electrolytes suffers irreversible loss and shuttle of the soluble intermediates. New batteries that adopt Li⁺-conductive polymer electrolytes to mitigate the shuttle problem are hindered by incomplete discharge of sulfur/selenium. To address the trade-off between energy and cycle life, a new electrolyte is proposed that reconciles the merits of liquid and polymer electrolytes while resolving each of their inferiorities. An in situ interfacial polymerization strategy is developed to create a liquid/polymer hybrid electrolyte between a LiPF₆-coated separator and the cathode. A polymer-gel electrolyte in situ formed on the separator shows high Li⁺ transfer number to serve as a chemical barrier against the shuttle effect. Between the gel electrolyte and the cathode surface is a thin gradient solidification layer that enables transformation from gel to liquid so that the liquid electrolyte is maintained inside the cathode for rapid Li⁺ transport and high utilization of active materials. By addressing the dilemma between the shuttle chemistry and incomplete discharge of S/Se, the new electrolyte configuration demonstrates its feasibility to trigger higher capacity retention of the cathodes. As a result, Li–S and Li–Se cells with high energy and long cycle lives are realized, showing promise for practical use.     

Identifying Hidden Li–Si–O Phases for Lithium-Ion Batteries via First-Principle Thermodynamic Calculations

SiO–based materials are promising alloys and conversion-type anode materials for lithium-ion batteries and are recently found to be excellent dendrite-proof layers for lithium-metal batteries. However, only a small fraction of the Li–Si–O compositional space has been reported, significantly impeding the understanding of the phase transition mechanisms and the rational design of these materials both as anodes and as protection layers for lithium-metal anodes. Herein, we identify three new thermod...     

Tailoring the Spatial Distribution and Content of Inorganic Nitrides in Solid–Electrolyte Interphases for the Stable Li Anode in Li–S Batteries

Among the alternatives to lithium-ion batteries, lithium–sulfur(Li–S)batteries are considered as an attractive option because of their high theoretical energy density of 2570 Wh kg^-1. However, the application of the Li–S battery has been plagued by the rapid failure of the Li anode due to the Li dendrite growth and severe parasitic reactions between Li and lithium polysulfides. The physicochemical properties of the solid–electrolyte interphase have a profound impact on the performance...     

A Fast Charging–Cooling Coupled Scheduling Method for a Liquid Cooling-Based Thermal Management System for Lithium-Ion Batteries

Efficient fast-charging technology is necessary for the extension of the driving range of electric vehicles. However, lithium-ion cells generate immense heat at high-current charging rates. In order to address this problem, an efficient fast charging–cooling scheduling method is urgently needed. In this study, a liquid cooling-based thermal management system equipped with mini-channels was designed for the fast-charging process of a lithium-ion battery module. A neural network-based regression model was proposed based on 81 sets of experimental data, which consisted of three sub-models and considered three outputs: maximum temperature, temperature standard deviation, and energy consumption. Each sub-model had a desirable testing accuracy (99.353%, 97.332%, and 98.381%) after training. The regression model was employed to predict all three outputs among a full dataset, which combined different charging current rates (0.5C, 1C, 1.5C, 2C, and 2.5C (1C = 5 A)) at three different charging stages, and a range of coolant rates (0.0006, 0.0012, and 0.0018 kg·s⁻¹). An optimal charging–cooling schedule was selected from the predicted dataset and was validated by the experiments. The results indicated that the battery module’s state of charge value increased by 0.5 after 15 min, with an energy consumption lower than 0.02 J. The maximum temperature and temperature standard deviation could be controlled within 33.35 and 0.8 °C, respectively. The approach described herein can be used by the electric vehicles industry in real fast-charging conditions. Moreover, optimal fast charging–cooling schedule can be predicted based on the experimental data obtained, that in turn, can significantly improve the efficiency of the charging process design as well as control energy consumption during cooling.     

Double-Walled NiTeSe–NiSe2 Nanotubes Anode for Stable and High-Rate Sodium-Ion Batteries

Electrodes made of composites with heterogeneous structure hold great potential for boosting ionic and charge transfer and accelerating electrochemical reaction kinetics. Herein, hierarchical and porous double-walled NiTeSe–NiSe₂ nanotubes are synthesized by a hydrothermal process assisted in situ selenization. Impressively, the nanotubes have abundant pores and multiple active sites, which shorten the ion diffusion length, decrease Na⁺ diffusion barriers, and increase the capacitance contribution ratio of the material at a high rate. Consequently, the anode shows a satisfactory initial capacity (582.5 mA h g⁻¹ at 0.5 A g⁻¹), a high-rate capability, and long cycling stability (1400 cycles, 398.6 mAh g⁻¹ at 10 A g⁻¹, 90.5% capacity retention). Moreover, the sodiation process of NiTeSe–NiSe₂ double-walled nanotubes and underlying mechanism of the enhanced performance are revealed by in situ and ex situ transmission electron microscopy and theoretical calculations.     

Highly Stable Silicon–Carbon–Nitrogen Composite Anodes from Silsesquiazane for Rechargeable Lithium-Ion Battery

Herein, we developed novel silicon–carbon–nitrogen(SiCN) composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.     

The Effect of Thermal Treatment on Properties of Composite Silicon–Carbon Anodes for Lithium-Ion Batteries

Technical Physics Letters - Influence exerted by the temperature of annealing in the atmosphere of argon on the ability of Si‒C nanocomposites to enable a reversible introduction of lithium...     

A Review on Engineering Design for Enhancing Interfacial Contact in Solid-State Lithium–Sulfur Batteries

The utilization of solid-state electrolytes(SSEs) presents a promising solution to the issues of safety concern and shuttle effect in Li–S batteries, which has garnered significant interest recently. However, the high interfacial impedances existing between the SSEs and the electrodes(both lithium anodes and sulfur cathodes) hinder the charge transfer and intensify the uneven deposition of lithium, which ultimately result in insufficient capacity utilization and poor cycling stability. Hence,the...     

Asymmetric Air Cathode Design for Enhanced Interfacial Electrocatalytic Reactions in High-Performance Zinc–Air Batteries

The rechargeable zinc–air battery (ZAB) is a promising energy storage technology owing to its high energy density and safe aqueous electrolyte, but there is a significant performance bottleneck. Generally, cathode reactions only occur at multiphase interfaces, where the electrocatalytic active sites can participate in redox reactions effectively. In the conventional air cathode, the 2D multiphase interface on the surface of the gas diffusion layer (GDL) inevitably results in an insufficient amount of active sites and poor interfacial contact, leading to sluggish reaction kinetics. To address this problem, a 3D multiphase interface strategy is proposed to extend the reactive interface into the interior of the GDL. Based on this concept, an asymmetric air cathode is designed to increase the accessible active sites, accelerate mass transfer, and generate a dynamically stabilized reactive interface. With a NiFe layered-double-hydroxide electrocatalyst, ZABs based on the asymmetric cathode deliver a small charge/discharge voltage gap (0.81 V at 5.0 mA cm⁻²), a high power density, and a stable cyclability (over 2000 cycles). This 3D reactive interface strategy provides a feasible method for enhancing the air cathode kinetics and further enlightens electrode designs for energy devices involving multiphase electrochemical reactions.     

Separator with Nitrogen–Phosphorus Flame-Retardant for LiNixCoyMn1−x−yO2 Cathode-Based Lithium-Ion Batteries

With the pursuit of high-energy-density for lithium-ion batteries (LIBs), the hidden safety problems of batteries have gradually emerged. LiNi_xCo_yMn_1−x−yO₂ (NCM) is considered as an ideal cathode material to meet the urgent needs of high-energy-density batteries. However, the oxygen precipitation reaction of NCM cathode at high temperature brings serious safety concerns. In order to promote high-safety lithium-ion batteries, herein, a new type of flame-retardant separator is prepared using flame-retardant (melamine pyrophosphate, MPP) and thermal stable Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). MPP takes the advantage of nitrogen–phosphorus synergistic effect upon the increased internal temperature of LIBs, including the dilution effect of noncombustible gas and the rapidly suppression of undesirable thermal runaway. The developed flame-retardant separators show negligible shrinkage over 200 °C and it takes only 0.54 s to extinguish the flame in the ignition test, which are much superior to commercial polyolefin separators. Moreover, pouch cells are assembled to demonstrate the application potential of PVDF-HFP/MPP separators and further verify the safety performance. It is anticipated that the separator with nitrogen–phosphorus flame-retardant can be extensively applied to various high-energy-density devices owing to simplicity and cost-effectiveness.     

In Situ 1D Carbon Chain-Mail Catalyst Assembly for Stable Lithium–Sulfur Full Batteries

The main obstacles for the commercial application of Lithium–Sulfur (Li–S) full batteries are the large volume change during charging/discharging process, the shuttle effect of lithium polysulfide (LiPS), sluggish redox kinetics, and the indisciplinable dendritic Li growth. Especially the overused of metal Li leads to the low utilization of active Li, which seriously drags down the actual energy density of Li–S batteries. Herein, an efficient design of dual-functional CoSe electrocatalyst encapsulated in carbon chain-mail (CoSe@CCM) is employed as the host both for the cathode and anode regulation simultaneously. The carbon chain-mail constituted by carbon encapsulated layer cross-linking with carbon nanofibers protects CoSe from the corrosion of chemical reaction environment, ensuring the high activity of CoSe during the long-term cycles. The Li–S full battery using this carbon chain-mail catalyst with a lower negative/positive electrode capacity ratio (N/P < 2) displays a high areal capacity of 9.68 mAh cm⁻² over 150 cycles at a higher sulfur loading of 10.67 mg cm⁻². Additionally, a pouch cell is stable for 80 cycles at a sulfur loading of 77.6 mg, showing the practicality feasibility of this design.     

“Dual- Engineering” Strategy to Regulate NH4V4O10 as Cathodes for High-Performance Aqueous Zinc Ion Batteries

Aqueous zinc ion batteries (AZIBs) have attracted attention as a promising candidate for secondary battery energy storage due to their safety and environmental benefits. However, the vanadium-based cathode material NH₄V₄O₁₀ has the problem of structural instability. In this paper, it is found by density functional theory calculation that excessive NH₄⁺ located in the interlayer will repel the Zn²⁺ during the process of Zn²⁺ insertion. This results in the distortion of the layered structure, further affects the diffusion of Zn²⁺ and reduces the reaction kinetics. Therefore, part of the NH₄⁺ is removed by heat treatment. In addition, the introduction of Al³⁺ into the material by hydrothermal method is able to further enhance its zinc storage properties. This dual-engineering strategy shows excellent electrochemical performance (578.2 mAh g⁻¹ at 0.2 A g⁻¹). This study provides valuable insights for the development of high performance AZIBs cathode materials.     

An Iron-Decorated Carbon Aerogel for Rechargeable Flow and Flexible Zn–Air Batteries

Mechanically stable and foldable air cathodes with exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are key components of wearable metal–air batteries. Herein, a directional freeze-casting and annealing approach is reported for the construction of a 3D honeycomb nanostructured, N,P-doped carbon aerogel incorporating in situ grown FeP/Fe₂O₃ nanoparticles as the cathode in a flexible Zn–air battery (ZAB). The aqueous rechargeable Zn–air batteries assembled with this carbon aerogel exhibit a remarkable specific capacity of 648 mAh g⁻¹ at a current density of 20 mA cm⁻² with a good long-term durability, outperforming those assembled with commercial Pt/C+RuO₂ catalyst. Furthermore, such a foldable carbon aerogel with directional channels can serve as a freestanding air cathode for flexible solid-state Zn–air batteries without the use of carbon paper/cloth and additives, giving a specific capacity of 676 mAh g⁻¹ and an energy density of 517 Wh kg⁻¹ at 5 mA cm⁻² together with good cycling stability. This work offers a new strategy to design and synthesize highly effective bifunctional air cathodes to be applied in electrochemical energy devices.     

Biomass-Derived Bifunctional Cathode Electrocatalyst and Multiadaptive Gel Electrolyte for High-Performance Flexible Zn–Air Batteries in Wide Temperature Range

High-efficiency and low-cost bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as well as gel electrolytes with high thermal and mechanical adaptability are required for the development of flexible batteries. Herein, abundant Setaria Viridis (SV) biomass is selected as the precursor to prepare porous N-doped carbon tubes with high specific surface area and the 900 °C calcination product of SV (SV-900) shows the optimum ORR/OER activities with a small E_OER–E_ORR of 0.734 V. Meanwhile, a new multifunctional gel electrolyte named C20E2G5 is prepared using cellulose extracted from another widely distributed biomass named flax as the skeleton, epichlorohydrin as the cross-linker and glycerol as the antifreezing agent. C20E2G5 possesses high ionic conductivity from −40 to + 60 °C, excellent tensile and compressive resistance, high adhesion, strong freezing and heat resistance. Moreover, the symmetrical cell assembled with C20E2G5 can significantly inhibit Zn dendrite growth. Finally, flexible solid-state Zn–air batteries assembled with SV-900 and C20E2G5 show high open circuit voltage, large energy density, and long-term operation stability between −40 and + 60 °C. This biomass-based approach is generic and can be used for the development of diverse next-generation electrochemical energy conversion and storage devices.