High Mass Loading Research Articles

Coupling of V2O5 structural design and electrolyte modulation toward stable zinc-ion battery

Layered vanadium oxides possess abundant crystal structures and multiple redox states, which account for excellent specific capacity for zinc ion batteries (ZIBs). However, vanadium-based cathodes typically suffer from structural instability and component dissolution, leading to inferior cyclic stability and rate performance. Herein, porous V2O5 slender leaf-like nanostructure anchored on carbon cloth (CC) is synthesized via electrodeposition and subsequent calcination. Taking advantage of the distinctive hierarchical structure and the introduction of propylene carbonate (PC) electrolyte additives, the free-standing VO-C2PC electrode provides a maximum reversible capacity of 555 mA h g−1 at 0.3 A g−1, and high capacity retention of 180 mA h g−1 after 5000 cycles at 10 A g−1. Even at a high mass loading, the VO-C2PC exhibits excellent Zn storage capability and stability. Furthermore, the Zn2+ storage mechanism reveals the gradual transformation of V2O5 into stable zinc pyrovanadate (ZVO) phase, which improves the stable Zn2+ storage capability. This study provides valuable insights into the construction of advanced electrodes and the design of novel electrolytes for high-performance ZIBs.

Tuning Proton Insertion Chemistry for Sustainable Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries (ZIBs) have emerged as an alternative to lithium-ion batteries due to their affordability and high level of safety. However, their commercialization is hindered by the low mass loading and irreversible structural changes of the cathode materials during cycling. Here, a disordered phase of a manganese nickel cobalt dioxide cathode material derived from wastewater via a coprecipitation process is reported. When used as the cathode for aqueous ZIBs , the developed electrode delivers 98% capacity retention at a current density of 0.1Ag-1 and 72% capacity retention at 1Ag-1 while maintaining high mass loading (15mgcm-2). The high performance is attributed to the structural stability of the Co and Ni codoped phase; the dopants effectively suppress Jahn-Teller distortion of the manganese dioxide during cycling, as revealed by operando X-ray absorption spectroscopy. Also, it is found that the Co and Ni co-doped phase effectively inhibits the dissolution of Mn2+, resulting in enhanced durability without capacity decay at first 20cycles. Further, it is found that the performance of the electrode is sensitive to the ratio of Ni to Co, providing important insight into rational design of more efficient cathode materials for low-cost, sustainable, rechargeable aqueous ZIBs.

10 μm-Level TiNb2 O7 Secondary Particles for Fast-Charging Lithium-Ion Batteries.

TiNb2 O7 with Wadsley-Roth phase delivers double theoretical specific capacity and similar working potential in comparison to spinel Li4 Ti5 O12 , the commercial high-rate anode material, and thus can enable much higher energy density of lithium-ion batteries. However, the inter-particle resistance within the high-mass-loading TiNb2 O7 electrode would impede the capacity release for practical application, especially under fast-charging conditions. Herein, 10-20 μm-size carbon-coated TiNb2 O7 secondary particle (SP-TiNb2 O7 ) consisting of initial micro-scale TiNb2 O7 particles (MP-TiNb2 O7 ) was fabricated. The high crystallinity of active material could enable fast-charge diffusion and electrochemical reaction rate within particles, and the small number of stacking layers of SP-TiNb2 O7 could reduce the large inter-particle resistance that regular particle electrode often possess and achieve high compaction density of electrodes with high mass loading. The investigation on materials structure and electrochemical reaction kinetics verified the advances of the as-fabricated SP-TiNb2 O7 in achieving superior electrochemical performance. The SP-TiNb2 O7 exhibited high reversible capacity of 292.7 mAh g-1 in the potential range of 1-3 V (Li+ /Li) at 0.1 C, delivering high-capacity release of 94.3 %, and high capacity retention of 86 % at 0.5 C for 250 cycles in half cell configuration. Particularly, the advances of such an anode were verified in practical 5 Ah-level laminated full pouch cell. The as-assembled LiFePO4 ||TiNb2 O7 full cell exhibited a high capacity of 5.08 Ah at high charging rate of 6 C (77.9 % of that at 0.2 C of 6.52 Ah), as well as an ultralow capacity decay rate of 0.0352 % for 250 cycles at 1 C, suggesting the great potential for practical fast-charging lithium-ion batteries.

Zn-In Alloying Powder Solvent Free Electrode Toward High-Load Ampere-Hour Aqueous Zn-Mn Secondary Batteries.

Aqueous Zn-ion batteries (ZIBs) are promising candidates for large-scale energy storage due to high safety, abundant reserves, low-cost, and high energy density. However, the reversibility of the metallic Zn anode in the mild electrolyte is still unsatisfactory, due to the Zn dendrite growth, hydrogen evolution, and corrosion passivation. Herein, a Zn-In alloying powder solvent free electrode is proposed to replace the Zn foil in ZIBs. The novel Zn anodes are constructed by a solvent-free manufacturing process with carbons, forming a 3D Zn deposition network and providing uniformly electric field distribution. The In on the Zn powder surface can increase the overpotential for hydrogen evolution and further improve the morphology of Zn deposition against dendrite growth. The Zn solvent-free electrodes enable the Zn-MnO2 batteries with high cathode loading mass of 10-20mg cm-2 to achieve >380 stable cycles. Furthermore, the assembled soft package batteries of 2.4 Ah (52Wh kg-2) is evaluated and the capacity retention is maintained at 80% after 200 cycles at a high areal capacity of 5 mAh cm-2 without gas evolution. This work offers a workable strategy to develop a durable Zn anode for the eventually commercial applications of aqueous Zn-Mn secondary batteries.

Mechanism of Bilayer Polymer-Based Electrolyte with Functional Molecules in Enhancing the Capacity and Cycling Stability of High-Voltage Lithium Batteries.

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) are favorable for all-solid-state lithium metal batteries (ASSLBs) to ensure safety and enhance energy density. However, their narrow work windows and unstable electrode/electrolyte interfaces hinder their practical application in high-voltage ASSLBs. Although introducing additives in SPEs has been proven to be effective to address the above issues, it could hardly optimize both cathode and anode interfaces by an individual additive. Herein, heterogeneously double-layer SPEs are constructed with two typical additives (LiPO2F2 and LiFSI), which are used to modify the LiNi0.6Co0.2Mn0.2O2 (NCM)-cathode/electrolyte interface (CEI) and lithium-anode/solid electrolyte interface (SEI), and further understand their respective mechanism in enhancing the capacity and cycling stability of ASSLBs. Specifically, LiPO2F2 not only leads to a uniform CEI layer to prevent the oxidation decomposition of PEO and LiTFSI but also ensures fast Li+ diffusion at high voltage (>3.9 V), improving the rate performances and life spans of the cells. The LiFSI contributes to a stable SEI layer with rich LiF, suppressing the growth of lithium dendrites and maximizing the specific capacity for ASSLBs. Integrating the advantages of the two functional molecules, the optimized ASSLB displays an excellent capacity of 141.4 mAh g-1 at 1C and an outstanding capacity retention of 81.6% after 400 cycles when using the NCM cathode, even reaching 154.2 mAh g-1 at 0.1 mA cm-2 with a high mass loading (6.4 mg cm-2). Additionally, the bilayer SPEs also match well with a LiFePO4 electrode with a high mass loading of 11.0 mg cm-2, displaying a high capacity of 155.7 mAh g-1 at 0.1 mA cm-2.

Unveiling the effect of alloy-type coating for lithium metal plating and stripping on anode-free lithium metal batteries

Li dendrite formation is the root cause of capacity fading in anode-free lithium metal batteries (AFLMBs). Previous studies have shown that Au coating on Cu can seed Li nucleation by forming Li3Au for smooth Li plating and improves the cycle life of Li||Cu cells. However, unlike Li||Cu cells with excessive Li supply, in practical AFLMBs (i.e., full-cell), the active lithium is limited from the lithium intercalation cathode. The introduction of alloy-type coatings may adversely affect the cycling stability due to the pulverization effect during alloying with Li (e.g., the volume expansion rate from Au to Li3Au is 337%). Here, we evaluate the full-cell performance of AFLMBs focusing on different thicknesses of Au coating (20, 50, and 100nm) and four coating layers (alloy-type: Au, Ag; non-alloy-type: Ni, Ti). Our results show that although the alloy-type coatings (i.e., Au and Ag) lower the lithiation overpotential, the full-cells equipped with these coatings experience faster capacity fading than those with pristine and non-alloy-type coatings. When the Au-coated Cu is paired with high-mass loading NMC622 cathode, the full-cells AFLMBs exhibit inferior performance with a low initial Coulombic efficiency (89.97% and 79.75% for 20 and 100nm thick Au coating) and accelerated capacity fading, producing plated Li with porous structure and carbonyl-rich solid electrolyte interphase. This study underscores the necessity of employing a full-cell configuration for evaluating Li plating-stripping efficacy in AFLMBs, emphasizing a transition from laboratory research to practical applications.

Interrelation Between External Pressure, SEI Structure, and Electrodeposit Morphology in an Anode‐Free Lithium Metal Battery

AbstractThe interrelation is explored between external pressure (0.1, 1, and 10 MPa), solid electrolyte interphase (SEI) structure/morphology, and lithium metal plating/stripping behavior. To simulate anode‐free lithium metal batteries (AF‐LMBs) analysis is performed on “empty” Cu current collectors in standard carbonate electrolyte. Lower pressure promotes organic‐rich SEI and macroscopically heterogeneous, filament‐like Li electrodeposits interspersed with pores. Higher pressure promotes inorganic F‐rich SEI with more uniform and denser Li film. A “seeding layer” of lithiated pristine graphene (pG@Cu) favors an anion‐derived F‐rich SEI and promotes uniform metal electrodeposition, enabling extended electrochemical stability at a lower pressure. State‐of‐the‐art electrochemical performance is achieved at 1MPa: pG‐enabled half‐cell is stable after 300 h (50 cycles) at 1 mA cm−2 rate −3 mAh cm−2 capacity (17.5 µm plated/stripped), with cycling Coulombic efficiency (CE) of 99.8%. AF‐LMB cells with high mass loading NMC622 cathode (21 mg cm−2) undergo 200 cycles with a CE of 99.4% at C/5‐charge and C/2‐discharge (1C = 178 mAh g−1). Density functional theory (DFT) highlights the differences in the adsorption energy of solvated‐Li+ onto various crystal planes of Cu (100), (110), and (111), versus lithiated/delithiated (0001) graphene, giving insight regarding the role of support surface energetics in promoting SEI heterogeneity.

A multifunctional Janus layer for LLZTO/PEO composite electrolyte with enhanced interfacial stability in solid-state lithium metal batteries

Flexible composite solid electrolytes (CSEs) show great potential in high-energy all-solid-state lithium metal batteries owing to their easy fabrication, good electrochemical properties, and high safety. However, it remains challenging to achieve good interfacial compatibility between inorganic fillers and polymer, which affects lithium-ion transport and electrochemical performances of CSEs. Herein, we design a Li6.4La3Zr1.4Ta0.6O12 (LLZTO) filler coated with 3-methacryloxypropyltrimethoxysilane (MEMO) Janus layer for poly(ethylene) oxide (PEO) electrolyte (denoted as MEMO@LLZTO-PEO). We demonstrate the effect of MEMO coating on ionic transport of CSEs by the combined experimental and theoretical methods. The MEMO Janus layer facilitates uniform dispersion of filler in polymer as well as dissociates more lithium salt, which leads to much improved ionic conductivity of MEMO@LLZTO-PEO (2.16 × 10−4 S cm−1 at 30 ℃). Besides, MEMO@LLZTO could immobilize lithium salt anions via hydrogen bonding interactions and F–O chemical bonding, leading to good lithium-ion transference number (0.53) of MEMO@LLZTO-PEO. Moreover, we prepare a nonwoven fabric (NF)-supported CSE (denoted as MEMO@LLZTO-PEO-NF) to further improve the mechanical strength and safety of CSEs. The MEMO@LLZTO-PEO-NF shows great cyclability over 4000 h in a lithium symmetrical cell at a current density of 0.1 mA cm−2 (areal capacity: 0.1 mAh cm−2, 60 ℃). When used in all-solid-state Li/LiFePO4 batteries with a high active mass loading (>4 mg cm−2), MEMO@LLZTO-PEO-NF cell shows much-enhanced cyclability and rate capability at 60 ℃. This work also provides a new strategy to achieve good interfacial compatibility between inorganic fillers and polymer matrix in composite solid electrolytes for all-solid-state lithium batteries.

Mechanochemistry transforming high-surface-area coal-based activated carbon into densified carbon with optimized multi-scale structures for enhanced sodium/potassium ion storage

Practical sodium/potassium-ion batteries require carbon anodes with both high gravimetric and volumetric performances, for which engineering carbon material with simultaneous high-density architecture and well-organized structures is the key. Herein, a simple and scalable strategy via a mechanochemistry process is developed to transform high-surface-area activated carbon into densified carbon with optimized multi-scale structures in term of greatly decreased ineffective pores, a shorten carbon lattice and modified carboxyl-dominant functional groups. In the mechanochemical process, the rearrangement of ineffective pores was achieved by high-energy collision and shear effects between grinding balls and particles, in which micropores were concentrated at ∼0.5 nm, followed by carboxylic modification on the fresh edges in air atmosphere (CO2). The reduced ineffective pores and enriched functional groups have improved reversibility and kinetics of Na/K ions storage in carbon matrix, resulting in large reversible capacities, excellent rate capabilities even at a high-loading mass of 5 mg·cm−2. Electrochemical kinetic analysis and ex-situ X-ray diffraction reveal the dominant capacitive storage mechanism for Na+, and theorical calculations demonstrate that the grafted carboxyl groups in carbon matrix promote Na+ reversible storage with multi-ion adsorption configuration, thus improving capacitive storage capacities. This work demonstrates the feasibility of transforming coal-based porous carbon into high-performance anode materials.

Evaluation of an efficient data-driven ANN model to predict agglomerate collisions within Euler–Lagrange simulations

In this study, a recently developed data-driven model for the collision-induced agglomerate breakup (CHERD 195, 2023) is evaluated. It is especially intended for Euler–Lagrange simulations of flows with high mass loadings, where coupled CFD–DEM predictions are too expensive. Therefore, a surrogate model relying on the hard-sphere approach in which agglomerates are represented by effective spheres was developed. Based on a variety of DEM simulations, artificial neural networks were trained to predict the post-collision number of arising fragments, their size distribution and their velocities. In the present contribution, the agglomerate collision model is assessed using the particle-laden flow through a T-junction. Since two fluid streams with agglomerates are injected at both opposite ends, the setup is particularly suitable for investigating breakage caused by collisions. Two flow configurations (laminar flow at Re = 130 and turbulent flow at Re = 8000) and two different powders (primary particle diameter of 0.97 and 5.08 micrometers) are taken into account. The latter allows to study the influence of the strength of the agglomerates on the collision-induced breakage. The laminar case offers the possibility to evaluate the effect of the collision angle in detail. The collision-induced breakage proves to be the most dominant deagglomeration mechanism in both the laminar and turbulent flow scenario. Nevertheless, the role of the fluid stresses and especially the drag stress becomes more prominent in the turbulent case, while in the laminar flow their effects are negligible.

Significant Strain Dissipation via Stiff-Tough Solid Electrolyte Interphase Design for Highly Stable Alloying Anodes.

The pulverization of alloying anodes significantly restricts their use in lithium-ion batteries (LIBs). This study presents a dual-phase solid electrolyte interphase (SEI) design that incorporates finely dispersed Al nanoparticles within the LiPON matrix. This distinctive dual-phase structure imparts high stiffness and toughness to the integrated SEI film. In comparison to single-phase LiPON film, the optimized Al/LiPON dual-phase SEI film demonstrates a remarkable increase in fracture toughness by 317.8%, while maintaining stiffness, achieved through the substantial dissipation of strain energy. Application of the dual-phase SEI film on an Al anode leads to a 450% enhancement in cycling stability for lithium storage in dual-ion batteries. A similar enhancement in cycling stability for silicon anodes, which face severe volume expansion issues, is also observed, demonstrating the broad applicability of the dual-phase SEI design. Specifically, homogeneous Li-Al alloying has been observed in conventional LIBs, even when paired with a high mass loading LiNi0.5Co0.3Mn0.2O2 cathode (7 mg cm-2). The dual-phase SEI film design can also accelerate the diffusion kinetics of Li-ions through interface electronic structure regulation. This dual-phase design can integrate stiffness and toughness into a single SEI film, providing a pathway to enhance both the structural stability and rate capability of alloying anodes.

Significant Strain Dissipation via Stiff‐Tough Solid Electrolyte Interphase Design for Highly Stable Alloying Anodes

AbstractThe pulverization of alloying anodes significantly restricts their use in lithium‐ion batteries (LIBs). This study presents a dual‐phase solid electrolyte interphase (SEI) design that incorporates finely dispersed Al nanoparticles within the LiPON matrix. This distinctive dual‐phase structure imparts high stiffness and toughness to the integrated SEI film. In comparison to single‐phase LiPON film, the optimized Al/LiPON dual‐phase SEI film demonstrates a remarkable increase in fracture toughness by 317.8 %, while maintaining stiffness, achieved through the substantial dissipation of strain energy. Application of the dual‐phase SEI film on an Al anode leads to a 450 % enhancement in cycling stability for lithium storage in dual‐ion batteries. A similar enhancement in cycling stability for silicon anodes, which face severe volume expansion issues, is also observed, demonstrating the broad applicability of the dual‐phase SEI design. Specifically, homogeneous Li−Al alloying has been observed in conventional LIBs, even when paired with a high mass loading LiNi0.5Co0.3Mn0.2O2 cathode (7 mg cm−2). The dual‐phase SEI film design can also accelerate the diffusion kinetics of Li‐ions through interface electronic structure regulation. This dual‐phase design can integrate stiffness and toughness into a single SEI film, providing a pathway to enhance both the structural stability and rate capability of alloying anodes.

Activating Organic Electrode via Trace Dissolved Organic Molecules.

Organic electrode materials have gained attention for their tunable structures and sustainability, but their low electronic conductivity requires the use of large amounts of carbon additives (30 wt %) and low mass loadings (<2 mg cm-2) in electrodes. Here, we synthesize dibenzo[b,i]phenazine-5,7,12,14-tetrone (DPT) as a cathode active material for an aqueous Zn battery and find that Zn2+ storage dominates the cathode reaction. This battery demonstrates high capacity (367 mAh g-1), high-rate performance, and superlong life (12000 cycles). Remarkably, despite DPT's insulative nature, even with a high mass loading (10 mg cm-2) and only 10 wt % carbon additives, the DPT-based cathode exhibits promising performance due to trace dissolved discharge product (DPTx-). During discharge, the DPT is reduced to trace amounts of dissolved DPTx- at the cathode surface, which in turn reduces the remaining solid DPT as a redox mediator. Furthermore, dissolution-redeposition results in the reduction of DPT size and the formation of pores, further activating the electrode.

Cation Defect-Engineered Boost Fast Kinetics of Two-Dimensional Topological Bi2 Se3 Cathode for High-Performance Aqueous Zn-Ion Batteries.

The challenge with aqueous zinc-ion batteries (ZIBs) lies in finding suitable cathode materials that can provide high capacity and fast kinetics. Herein, two-dimensional topological Bi2 Se3 with acceptable Bi-vacancies for ZIBs cathode (Cu-Bi2-x Se3 ) is constructed through one-step hydrothermal process accompanied by Cu heteroatom introduction. The cation-deficient Cu-Bi2-x Se3 nanosheets (≈4nm) bring improved conductivity from large surface topological metal states contribution and enhanced bulk conductivity. Besides, the increased adsorption energy and reduced Zn2+ migration barrier demonstrated by density-functional theory (DFT) calculations illustrate the decreased Coulombic ion-lattice repulsion of Cu-Bi2-x Se3 . Therefore, Cu-Bi2-x Se3 exhibits both enhanced ion and electron transport capability, leading to more carrier reversible insertion proved by in situ synchrotron X-ray diffraction (SXRD). These features endow Cu-Bi2-x Se3 with sufficient specific capacity (320mAhg-1 at 0.1Ag-1 ), high-rate performance (97mAhg-1 at 10Ag-1 ), and reliable cycling stability (70mAhg-1 at 10Ag-1 after 4000 cycles). Furthermore, quasi-solid-state fiber-shaped ZIBs employing the Cu-Bi2-x Se3 cathode demonstrate respectable performance and superior flexibility even under high mass loading. This work implements a conceptually innovative strategy represented by cation defect design in topological insulator cathode for achieving high-performance battery electrochemistry.

Sulfone-functionalized metal–organic framework aerogels for selective CO2 capture from natural gas

The accumulation of CO2 in natural gas may reduce the heating value and even pose a risk of corrosion in transport pipelines, making the effective removal of CO2 highly essential. Metal–organic frameworks (MOFs), known for their high specific area and large porosity, show promising application in CO2 capture. However, a major obstacle is their intrinsic fragility and poor physicochemical stability. Herein, we present a sulfone-incorporated in-situ growth and fiber freeze-shaping strategy to develop lightweight, robust, and multiscale porous sulfone-functionalized UiO-67 (UiO-67-SO2) aerogels supported by aramid nanofibers. The resulting UiO-67-SO2 aerogels exhibit remarkable structural features, including a high MOF loading mass (64.39 wt%), low density (5.31 mg/cm3), high specific surface area (769.98 m2g−1), and large porosity (99.24 %). Moreover, owing to the introduction of CO2-philic sulfone groups, the UiO-67-SO2 aerogels exhibit high CO2 adsorption capacity (5.88 mmol/g), a high CO2/CH4 adsorption selectivity (43), and only a 2.77 % decline in their initial CO2 adsorption capacity after 10 cycles. The adsorption energy calculated by density functional theory method further confirms the strong interactions between UiO-67-SO2 aerogels and CO2 molecules. This work presents a promising direction for developing multiscale porous UiO-67-SO2 aerogels for the highly selective removal of CO2 from natural gas.

Revisiting Amides as Cosolvents for Flame Resistant Sodium Bis(oxalato)borate in Triethyl Phosphate Electrolyte

AbstractIn selecting electrolytes for Na‐ion batteries, simply importing the analogue of common lithium‐ion battery electrolytes to sodium‐ion batteries does not address safety concerns like toxicity and flammability. Electrolytes based on sodium bis(oxalato)borate (NaBOB) in organophosphates like triethyl phosphate (TEP) largely alleviate these specific safety concerns. However, it may be beneficial to obtain solutions with higher ionic conductivities than NaBOB in TEP, and compare the performance in Na‐ion batteries with high mass loading electrodes. Here, we have shown that N,N‐dimethyl formamide (DMF), N,N‐dimethyl acetamide (DMAc), and N‐methyl pyrrolidone (NMP) cosolvents almost double the ionic conductivity (from ~3.5 mS/cm to ~7 mS/cm) without sacrificing the flame‐retarding properties of the base NaBOB in TEP electrolyte. The physical properties of these cosolvent electrolyte mixtures are investigated, along with the electrochemical performance of these electrolytes full‐cells based on hard carbon anodes and Prussian white cathodes with near‐commercial areal capacity (~2 mAh/cm2).

Sulfur‐Tuned Advanced Carbons of Novel Properties and Scalable Productivity

AbstractSulfur‐tuned advanced carbons (STACs) with high mass loadings of sulfur are synthesized using an environmentally benign and scalable steam‐assisted sulfur insertion (SASI) method. While steam provides the pressure necessary to promote deep and rapid sulfur insertion into a carbon porous structure, a strong affinity between melted sulfur and carbon excludes water from pore penetration. The resulting STACs exhibit sulfur mass loadings up to 85% and the electrical conductivity of the carbon framework is largely preserved. The sulfur penetration can be tuned to fill specific pore sizes, enabling pore‐size‐dependent allocation of sulfur and controllable porosity, while sulfur lines the carbon pore surfaces. A significant amount of sulfur is in the monoclinic γ phase. To demonstrate their energy and environmental applications, the STACs are used as cathode materials in rechargeable aluminum‐sulfur batteries and as adsorption materials for spilled oil removal.

Multi-layering of carbon conductivity enhancers for boosting rapid recharging performance of high mass loading lithium ion battery electrodes

The ability of lithium ion batteries (LIBs) to provide rapid charging characteristics while retaining a substantial energy storage capacity is of paramount significance for their applicability in portable smart electronic devices. In this research, an effective approach to enhance re-charging rates of LIB cells was developed through incorporating carbon nanotube (CNT) conductivity boosters strategically into Li4Ti5O12 (LTO) electrodes. A layer-by-layer spray coating was exploited to manufacture multi-layer architectures that comprise sequential, discrete electrode layers of CNT-rich LTO and CNT-free LTO, aiming at promoting charge transfer kinetics of high mass loading electrodes. Initially, the optimal proportion of a CNT-rich layer and its best location within multi-layer electrode structures were investigated in half-cell configurations. The best performing multi-layer was then paired with a spray-coated LiFePO4 (LFP) positive electrode in full-cell LIBs, offering attractive power performance of ∼ 1500 W/kg that outperformed conventional LTO || LFP combinations.

An aqueous BiI3-Zn battery with dual mechanisms of Zn2+ (de)intercalation and I−/I2 redox

The development of aqueous battery with dual mechanisms is now arousing more and more interest. The dual mechanisms of Zn2+ (de)intercalation and I−/I2 redox bring unexpected effects. Herein, differing from previous studies using ZnI2 additive, this work designs an aqueous BiI3-Zn battery with self-supplied I−. Ex situ tests reveal the conversion of BiI3 into Bi (discharge) and BiOI (charge) at the 1st cycle and the dissolved I− in electrolyte. The active I− species enhances the specific capacity and discharge medium voltage of electrode as well as improves the generation of Zn dendrite and by-product. Furthermore, the porous hard carbon is introduced to enhance the electronic/ionic conductivity and adsorb iodine species, proven by experimental and theoretical studies. Accordingly, the well-designed BiI3-Zn battery delivers a high reversible capacity of 182 mA h g−1 at 0.2 A g−1, an excellent rate capability with 88 mA h g−1 at 10 A g−1, and an impressive cyclability with 63% capacity retention over 20 K cycles at 10 A g−1. An excellent electrochemical performance is obtained even at a high mass loading of 6 mg cm−2. Moreover, a flexible quasi-solid-state BiI3-Zn battery exhibits satisfactory battery performances. This work provides a new idea for designing high-performance aqueous battery with dual mechanisms.

High mass loading of polypyrrole in conductive hydrogels for stretchable all-in-one supercapacitors and self-powered strain sensing system

Developing high mass loading of conducting polymers in hydrogels for flexible supercapacitors remains an enormous challenge. Herein, we demonstrate an effective and facile strategy for incorporating high mass-loading of polypyrrole (PPy) nanoparticles into an open porous polydopamine/polyacrylamide (PDA/PAAM) hydrogel substrate. The as-prepared PDA/PAAM/PPy hydrogels exhibit great stretchability and desirable self-healing properties. Taking advantage of the sandwiched configuration and high mass of electroactive PPy (up to 11.13 mg/cm2), the PDA/PAAM/PPy hydrogels could be directly used as all-in-one supercapacitors, which can deliver a superior specific capacitance of 860 mF/cm2 at 1.0 mA/cm2, an excellent energy density of 76.44 μWh/cm2, a maximum power density of 4 mW/cm2, and excellent capacitance retention of 85 % after 5000 cycles. What’s more, the PDA/PAAM/PPy hydrogels show significant strain-sensitive behavior. A self-powered sensing system integrating the supercapacitor and strain sensor is achieved to monitor various human motions. Therefore, the resultant hydrogels have potential applications in wearable electronics.