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At least 55 records · Page 3

Beyond the Polysulfide Shuttle and Lithium Dendrite Formation: Addressing the Sluggish Sulfur Redox Kinetics for Practical High-Energy Li-S Batteries

Electrolyte modulation simultaneously suppresses polysulfide the shuttle effect and lithium dendrite formation of lithium-sulfur (Li-S) batteries. However, the sluggish S redox kinetics, especially under high S loading and lean electrolyte operation, has been ignored, which dramatically limits the cycle life and energy density of practical Li-S pouch cells. In this work, we demonstrate that a rational combination of selenium doping, core-shell hollow host structure, and fluorinated ether electrolytes enables ultrastable Li stripping/plating and essentially no polysulfide shuttle as well as fast redox kinetics. Thus, high areal capacity (>4 mAh cm -2 ) with excellent cycle stability and Coulombic efficiency were both demonstrated in Li metal anode and thick S cathode (4.5 mg cm -2 ) with a low electrolyte/sulfur ratio (10 mu L mg(-1)). Overall, this research further demonstrates a durable Li-Se/S pouch cell with high specific capacity, validating the potential practical applications.

25 ENERGY STORAGE↗

Scalable mechanochemical synthesis of high-quality Prussian blue analogues for high-energy and durable potassium-ion batteries

Prussian blue analogues (PBAs) are recognized as promising cathode materials for potassium-ion batteries (PIBs), particularly the low-cost and high-energy K 2 Mn[Fe(CN) 6 ](KMnF). However, conventional solution-based synthesis inevitably introduces [Fe(CN) 6 ] 4− defects and lattice water while suffering low synthesis efficiency, unfavorable to the improvement of electrochemical performance and scalability. Here, in this work, we report a simple solvent-free mechanochemical strategy for the synthesis of a wide variety of K 2 M[Fe(CN) 6 ] (M = Mn, Mg, Ca, etc.) with negligible defects and water, and it is unprecedented to achieve kilogram-level products of high-quality KMnF within just 10 minutes. The as-prepared KMnF delivers a high energy density of 590 Wh kg −1 at 0.2 C and exhibits an astonishing stability over 10 000 cycles and rate ability up to 50 C in a potassium metal half-cell. Encouragingly, a high-areal-capacity pouch cell with 2.2 mAh cm −2 (16.5 mg cm −2 ) exhibits a capacity retention of 80.7% after 500 cycles. Furthermore, systematic in situ characterization reveals underlying mechanism insights into structure–performance relationships. Specifically, the fully coordinated Mn–N 6 octahedral configuration effectively suppresses Mn 3+ Jahn–Teller distortion, enabling reversible phase transitions under both high-voltage and long-term cycling conditions. In addition, minimal defects provide sufficient redox centers, while the continuous three-dimensional framework facilitates rapid K + diffusion kinetics. This work provides a new opportunity for the ultrafast, universal and scalable synthesis of high-quality PBAs, facilitating the practical application of PIBs while enabling precise structural and compositional design of novel PBAs.

Mechanochemical method↗

High Depth‐of‐Discharge Zinc Rechargeability Enabled by a Self‐Assembled Polymeric Coating

Abstract Zinc has the potential for widespread use as an environmentally friendly and cost‐effective anode material pending the resolution of rechargeability issues caused by active material loss and shape change. Here, a self‐assembled Nafion‐coated Celgard 3501 (NC‐Celgard) separator is shown to enable unprecedented cycle life of a Zn anode in alkaline electrolyte at high depth‐of‐discharge (DOD Zn ). Using commercially relevant energy‐dense electrodes with high areal capacities of 60 mAh cm –2 , Zn–Ni cells tested at 20% DOD Zn cells achieve over 200 cycles while 50% DOD Zn cells achieve over 100 cycles before failure. The 20% and 50% DOD cells deliver an average of 132 and 180 Wh L –1 per cycle over their lifetime respectively. Rechargeability is attributed to the highly selective diffusion properties of the 300 nm thick negatively charged Nafion coating on the separator which prevents shorting by dendrites and inhibits redistribution of the active material. Crossover experiments show that the NC‐Celgard separator is practically impermeable to zincate ([Zn(OH) 4 ] 2– ), outperforming commercial Celgard, cellophane, Nafion 211 and 212 separators while still allowing hydroxide transport. This work demonstrates the efficacy of selective separators for increasing the cycle life of energy‐dense Zn electrodes without adding significant volume or complexity to the system.

Arnot, David J.↗

Understanding thermal and mechanical effects on lithium plating in lithium-ion batteries

Lithium plating is one of the main concerns for cell durability, as cyclable lithium and cell capacity are decreased during the process. Thermal and mechanical loads can influence cell behavior, including lithium plating driving forces, as suggested by the Arrhenius equation and the Bruggeman relation, respectively. Hence, a 1D and a 3D model are employed to study the thermal and mechanical effects on lithium plating in a lithium-ion battery with a high areal capacity (4 mAh/cm 2 ). The 1D model assumes uniform mechanical and temperature profile, while the 3D model is capable of capturing the nonuniformity of stress and temperature in the cell. Further, the effects of mechanical deformation and different temperatures on the process of lithium plating are investigated in this study. With the help of the 1D charging simulations, it is observed that lower temperatures increase the risk of lithium plating and the presence of mechanical deformations can accelerate its initiation. Furthermore, 3D charging simulations indicated that folds and boundaries of jellyrolls are more susceptible to lithium plating due to the higher stress concentration and lower temperature, respectively.

25 ENERGY STORAGE↗

Electrolyte design for Li metal-free Li batteries

Li metal, with the lowest thermodynamically achievable negative electrochemical potential and the highest specific capacity (3860 mAh g -1 ), is the ultimate anode choice for Li batteries. However, the highest reported Li plating/stripping Coulombic efficiency (CE) of 99.5% after extensive efforts is still too low for the Li metal-free (all the Li metal in cycling comes from cathode, without anode pre-lithiation) Li metal batteries. The low CE is attributed to both non-uniform Li plating/stripping on the lithiophobic Cu current collector and Li dendrite growth through lithiophilic organic–inorganic solid electrolyte interphase (SEI) formed in carbonate electrolytes. Here, we use a lithiophilic Bismuth graphite blend (Bi–Gr) substrate to replace lithiophobic Cu current collector to seed a uniform Li nucleation, and form a lithiophobic LiF-rich SEI rather than lithiophilic organic-rich SEI to suppress Li dendrite growth. Molecular dynamics simulations reveal the preferential reduction of anions in 2.0 M LiPF 6 in tetrahydrofuran/2-methyl tetrahydrofuran (2.0 M LiPF 6 –mixTHF) electrolyte to generate LiF-rich SEI on plated Li. Bi–Gr substrate and 2.0 M LiPF 6 –mixTHF electrolyte enable the Li anodes to achieve a record high CE of 99.83% at a high capacity of 1.0 mAh cm -2 and current of 0.5 mA cm -2 . The Bi particles serve as dispersed nucleation centers that promote uniform Li deposition with strong adhesion to the substrate to avoid dead Li, while the lithiophobic LiF-rich SEI promotes lateral Li growth and suppresses the vertical Li dendrite growth even at a high current density of 3.0 mA cm -2 and high areal capacities of 3.0 mAh cm -2 . The regulation of Li nucleation and growth enables the Li metal-free LiFePO 4 full cells to achieve 100 cycles at a practical areal capacity of >2.0 mAh cm -2 . This article highlights the benefits of simultaneous substrate design to improve Li nucleation and electrolyte design to promote lithiophobic SEI growth, enabling a promising and practical route Li metal-free Li metal batteries.

36 MATERIALS SCIENCE↗

High-Performance Solid-State Lithium-Ion Battery with Mixed 2D and 3D Electrodes

It is well established that the miniaturization of batteries has not kept pace with the miniaturization of electronics. Three-dimensional (3D) batteries, which were developed with the intent of improving microbattery performance, have had limited success because of fabrication challenges and material constraints. Solid-state, 3D batteries have been particularly susceptible to these shortcomings. In this paper we demonstrate that the incorporation of a high conductivity, solid electrolyte is the key to achieving a non-planar solid-state battery with high areal-capacity and high power-density. The model, 2.5D platform used in this study is a modification of the more typical 3D configuration in that it is comprised of a cathode array of pillars (3D) and a planar (2D) anode. This 2.5D geometry exploits the use of a high conductivity, ionogel electrolyte (10 -3 S cm -1 ) which interpenetrates the 3D electrode array. The 2.5D battery offers high areal energy densities from the post array while the high-conductivity, solid electrolyte enables high power densities (3.7 mWh cm -2 at 2.8 mW cm -2 ). Here, the reported solid-state 2.5D device exceeds the energy and power densities of any 3D solid-state system and the derived multiphysics model provides guidance for achieving significantly higher energy and power densities.

2.5D batteries↗

Regulating Li Nucleation and Growth Heterogeneities via Near-Surface Lithium-Ion Irrigation for Stable Anode-Less Lithium Metal Batteries

The inhomogeneous nucleation and growth of Li dendrite combined with the spontaneous side reactions with the electrolytes dramatically challenge the stability and safety of Li metal anode (LMA). Despite tremendous endeavors, current success relies on the use of significant excess of Li to compensate the loss of active Li during cycling. Herein, a near-surface Li + irrigation strategy is developed to regulate the inhomogeneous Li deposition behavior and suppress the consequent side reactions under limited Li excess condition. The conformal polypyrrole (PPy) coating layer on Cu surface via oxidative chemical vapor deposition technique can induce the migration of Li + to the interregional space between PPy and Cu, creating a near-surface Li + -rich region to smooth diffusion of ion flux and uniform the deposition. Moreover, as evidenced by multiscale characterizations including synchrotron high-energy X-ray diffraction scanning, a robust N-rich solid-electrolyte interface (SEI) is formed on the PPy skeleton to effectively suppress the undesired SEI formation/dissolution process. Strikingly, stable Li metal cycling performance under a high areal capacity of 10 mAh cm -2 at 2.0 mA cm -2 with merely 0.5 × Li excess is achieved. The findings not only resolve the long-standing poor LMA stability/safety issues, but also deepen the mechanism understanding of Li deposition process.

25 ENERGY STORAGE↗

Covalent Organic Framework as an Efficient Protection Layer for a Stable Lithium‐Metal Anode

Abstract Lithium (Li) metal shows great potential for achieving high‐energy‐density rechargeable batteries. However, the practical applications of Li‐metal batteries are still challenged by the formation of Li dendrites and unstable solid‐electrolyte interphase (SEI) on metallic Li. Herein, a thin covalent organic framework layer is in situ fabricated on Li (COF‐Li) to suppress Li dendrite growth and mitigate the side reaction on the Li anode. The COF has a periodic and uniform porosity, allowing for selectively sieving Li ions and guiding a uniform Li deposition. As a result, the COF‐Li exhibits a non‐dendrite morphology during repeated Li plating/stripping and demonstrates a remarkable cycle life over 13 200 h with an extremely low overpotential of only 16 mV at a high current density of 10 mA cm −2 and a high areal capacity of 10 mAh cm −2 .

He, Jiarui↗

Covalent Organic Framework as an Efficient Protection Layer for a Stable Lithium-Metal Anode

We report Lithium (Li) metal shows great potential for achieving high-energy-density rechargeable batteries. However, the practical applications of Li-metal batteries are still challenged by the formation of Li dendrites and unstable solid-electrolyte interphase (SEI) on metallic Li. Herein, a thin covalent organic framework layer is in situ fabricated on Li (COF-Li) to suppress Li dendrite growth and mitigate the side reaction on the Li anode. The COF has a periodic and uniform porosity, allowing for selectively sieving Li ions and guiding a uniform Li deposition. As a result, the COF-Li exhibits a non-dendrite morphology during repeated Li plating/stripping and demonstrates a remarkable cycle life over 13 200 h with an extremely low overpotential of only 16 mV at a high current density of 10 mA cm -2 and a high areal capacity of 10 mAh cm -2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

From Sodium–Oxygen to Sodium–Air Battery: Enabled by Sodium Peroxide Dihydrate

Metal-air batteries have attracted extensive research interests due to their high theoretical energy density. However, most of the previous studies were limited by applying pure oxygen in the cathode, sacrificing the gravimetric and volumetric energy density. Here, we develop a real sodium-"air" battery, in which the rechargeability of the battery relies on the reversible reaction of the formation of sodium peroxide dihydrate (Na 2 O 2 ∙ 2H 2 O). After an oxygen evolution reaction catalyst is applied, the charge overpotential is largely reduced to achieve a high energy efficiency. The sodium-air batteries deliver high areal capacity of 4.2 mAh.cm -2 and have a decent cycle life of 100 cycles. The oxygen crossover effect is largely suppressed by replacing the oxygen with air, whereas the dense solid electrolyte interphase formed on the sodium anode further prolongs the cycle life.

25 ENERGY STORAGE↗

Li 3– x Zr x (Ho/Lu) 1– x Cl 6 Solid Electrolytes Enable Ultrahigh-Loading Solid-State Batteries with a Prelithiated Si Anode

We report two new families of lithium metal chloride solid electrolytes Li 3–x Zr x (M) 1–x Cl 6 (0 ≤ x ≤ 0.8; M = Ho or Lu) with ionic conductivities of up to 1.8 mS cm –1 and a low activation energy of 0.34 eV. Structural elucidation via high-resolution neutron diffraction determines the Li ion distribution in trigonal Li 3 HoCl 6 , orthorhombic-I Li 3 LuCl 6 , and orthorhombic-II Li 2.4 Zr 0.6 (Ho/Lu) 0.4 Cl 6 . The last compound exhibits well-connected Li-ion pathways and abundant Li-ion carriers/vacancies to promote diffusion. All-solid-state batteries with Li 2.6 Zr 0.4 (Ho/Lu) 0.6 Cl 6 solid electrolytes and NCM85 cathodes exhibit stable cycling up to 4.6 V vs Li + /Li, which is even preserved up to 4.8 V. Stable cathode interphases are formed for both electrolytes upon cycling to 4.3, 4.6, and 4.8 V cutoff potentials, as identified by a ToF-SIMS analysis. Solid-state cells with a prelithiated Li 0.7 Si anode exhibit a significantly increased initial coulombic efficiency of 94.5% compared to Si and a high areal capacity of up to 16.3 mAh·cm –2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Aqueous Ni-rich-cathode dispersions processed with phosphoric acid for lithium-ion batteries with ultra-thick electrodes

Lithium-ion battery (LIB) production can benefit both economically and environmentally from aqueous processing. Although these electrodes have the potential to surpass electrodes conventionally processed with N -methyl-2-pyrrolidone (NMP) in terms of performance, significant issues still exist with respect to ultra-thick cathodes ($\gg$4 mAh/cm 2 areal capacities). A major concern for these types of electrodes with high-nickel active material stems from lithium leaching from active material, which drives the pH of the dispersion in excess of 12 and subsequently corrodes the current collector interface. As this corrosion reaction proceeds, hydrogen generation at the interface creates bubbles which cause severe cracking in the dried electrode surface. When areal loadings are increased, this effect becomes more pronounced and is detrimental to both mechanical and electrochemical properties of these electrodes. In this work, a technique for mitigating corrosion at the current collector by adjusting the pH of the dispersion with the addition of phosphoric acid is investigated. Phosphoric acid was added in 0.5 wt% increments between 0.0 and 1.5 wt%, and effects on rheology, adhesion, corrosion, and electrochemical performance were investigated. A technique is reported for producing aqueous processed cathodes with areal loadings of 6–8 mAh/cm 2 with reduced surface cracking and superior high-rate discharge capacity (i.e. high-power performance) for this class of cathode loadings.

25 ENERGY STORAGE↗

Fast Kinetics Design for Solid‐State Battery Device

Abstract Fast kinetics of solid‐state batteries at the device level is not adequately explored to achieve fast charging and discharging. In this work, a leap forward is achieved for fast kinetics in full cells with high cathode loading and areal capacity. This kinetic improvement is achieved by designing a hierarchical structure of electrode composites. In the cathode, the authors’ design enables high areal capacities above 3 mAh cm −2 to be stably cycled at high current densities of ≈13–40 mA cm −2 , yielding a C‐rate from 5 to 10 C. In the anode, the authors’ design breaks the common rule of the negative correlation between critical C‐rate and the discharge voltage that is observed in most other anodes. The overall design enables the fast cycling of such batteries for over 4000 cycles at room temperature and 5 C charge‐rate. The design principles unveiled by this work help to understand critical kinetic processes in battery devices that limit the fast cycling at high cathode loading and speed up the design of high‐performance solid‐state batteries.

Wang, Yichao↗

Revisiting the Role of Conductivity and Polarity of Host Materials for Long-Life Lithium–Sulfur Battery

Despite their high theoretical energy density and low cost, lithium-sulfur batteries (LSBs) suffer from poor cycle life and low energy efficiency owing to the polysulfides shuttle and the electronic insulating nature of sulfur. Conductivity and polarity are two critical parameters for the search of optimal sulfur host materials. However, their role in immobilizing polysulfides and enhancing redox kinetics for long-life LSBs are not fully understood. In this work we have conducted an evaluation on the role of polarity over conductivity by using a polar but nonconductive platelet ordered mesoporous silica (pOMS) and its replica platelet ordered mesoporous carbon (pOMC), which is conductive but nonpolar. It is found that the polar pOMS/S cathode with a sulfur mass fraction of 80 wt% demonstrates outstanding long-term cycle stability for 2000 cycles even at a high current density of 2C. Furthermore, the pOMS/S cathode with a high sulfur loading of 6.5 mg cm -2 illustrates high areal and volumetric capacities with high capacity retention. Complementary physical and electrochemical probes clearly show that surface polarity and structure are more dominant factors for sulfur utilization efficiency and long-life, while the conductivity can be compensated by the conductive agent involved as a required electrode material during electrode preparation. The present findings shed new light on the design principles of sulfur hosts towards long-life and highly efficient LSBs.

25 ENERGY STORAGE↗

Unraveling the Effects of Hierarchical Bimodal Microscale Porosity on Thick Electrodes

The thick electrode design is preferential in high-energy lithium-ion batteries (LIBs) systems. However, the sluggish ionic transport in homogeneous porous thick electrodes severely limits the areal capacity at high charging/discharging rates. The hierarchical porous design is a promising approach to mitigate kinetic limitations because it can distribute mass effectively in natural systems. In this study, the effects of bimodal microscale pores are fully investigated in thick electrodes from both architectural and electrochemical perspectives. Notably, by introduction of the bimodal microscale porous structure, the rate capability improves remarkably in thick electrodes with a low porosity (39%). Herein, by combining experimental results with simulations, this work presents a rational design guideline for preparing thick electrodes with a porosity at the commercial level, as well as simultaneous high energy and power densities, which brings new insights into the advanced electrode architecture design in scalable high-energy and high-power energy storage systems for practical applications.

25 ENERGY STORAGE↗

Recent Advances in Scalable, High‐Mass Loaded Electrodes for Grid‐Scale Energy Storage

Abstract The increasing electrification of daily life as well as the intermittent characteristic of renewable energy sources require viable solutions for grid‐scale energy storage. Critical considerations for grid storage applications are electrode mass loading and electrode thickness as these features govern battery pack energy density, an important factor in determining manufacturing costs. For this reason, there is increased interest in finding new ways of creating electrodes with high mass loading. In this review, various high‐mass loading fabrication approaches are considered for positive electrode materials used in batteries. The benchmark used for high mass loading is above 20 mg cm −2 , which is higher than the practical limit of conventional tape‐cast electrodes. Several different electrode approaches are described including templating, laser patterning, direct ink writing, and electrodeposition. A variety of materials are covered with the most prominent being LiFe(PO 4 ) (LFP), LiCoO 2 (LCO), and MnO 2 . In research to date, scalable electrochemical performance has been achieved with mass loadings over 100 mg cm −2 . Areal capacities as high as 14.7 mAh cm −2 at 1.82 mA cm −2 have been achieved in non‐aqueous electrolytes and 9.8 mAh cm −2 at 10 mA cm −2 in aqueous electrolytes. These results establish that the mass loading of electrodes can be scaled up without compromising their electrochemical properties.

White, Makena [Department of Materials Science and↗

Stress- and interface-compatible red phosphorus anode for high-energy and durable sodium-ion batteries

Sodium-ion battery is a promising candidate for energy storage application, but the absence of high-capacity and low-cost anode materials significantly limit their practical specific energy and cost. Red phosphorus (RP) possesses a high theoretical specific capacity but suffers from large volume change, low electronic conductivity and unstable solid-electrolyte interphase (SEI). Herein, a hierarchical micro/nanostructured antimony-doped RP/carbon anode was developed, which demonstrate extraordinary electrochemical performance with high initial Coulombic efficiency of ~90%, high areal (~1.7 mAh cm-2) capacity together with good cycle stability and rate capability. Combined experimental and computational studies consistently revealed that such a unique structural design can dramatically accommodate the mechanical stress and moreover effectively restrain the undesired decomposition of electrolyte solvents regardless of electrolytes formulation, resulting in superior structural integrity and thin/robust SEI formation during cycling. The present finding has offered an alternative strategy for stress management and interface engineering on high-capacity alloying-based anode materials.

Liu, Xiang↗

Highly reversible Zn anode with a practical areal capacity enabled by a sustainable electrolyte and superacid interfacial chemistry

Aqueous zinc-metal batteries are plagued by poor Zn reversibility owing to zinc dendrite and layered double hydroxide (LDH) formation. Here, we introduce a novel additive—N,N-dimethylformamidium trifluoromethanesulfonate (DOTf)—in a low-cost aqueous electrolyte that can very effectively address these issues. The initial water-assisted dissociation of DOTf into triflic superacid creates a robust nanostructured solid-electrolyte interface (SEI)—revealed by operando spectroscopy and cryomicroscopy—which excludes water and enables dense Zn deposition. We demonstrate excellent Zn plating/stripping in a Zn||Cu asymmetric cell for more than 3,500 cycles. Furthermore, near 100% CE is realized at a combined high current density of 4 mA cm -2 and an areal capacity of 4 mAh cm -2 over long-term cycling. Zn||Zn 0.25 V 2 O 5 ·nH 2 O full cells retain ~83% of their capacity after 1,000 cycles with mass-limited Zn anodes. By restricting the depth of discharge, the cathodes exhibit less proton intercalation and LDH formation with an extended lifetime of 2,000 cycles.

25 ENERGY STORAGE↗