Poor Cycling Research Articles

Permeable void-free interface for all-solid-state alkali-ion polymer batteries.

All-solid-state batteries suffer from a loss of contact between the electrode and electrolyte particles, leading to poor cyclability. Here, a void-free ion-permeable interface between the solid-state polymer electrolyte and electrode is constructed in situ during cycling using charge/discharge voltage as the stimulus. During the charge-discharge, the permeation phase fills the voids at the interface and penetrates the electrode, forming strong bonds with the cathode and effectively mitigating the contact problem. Our all-solid-state potassium ion polymer batteries maintain high Coulombic efficiency more than 2000 cycles at a high operating voltage of 4.5 volt and stably cycle more than 500 cycles even at 4.6 volt. Our rational design for mitigating the contact problem is versatile, as demonstrated by the scalability of all-solid-state graphite-based polymer potassium-ion pouch cells and all-solid-state lithium-ion polymer batteries.

N-doped LiNi0.65Co0.15Mn0.2O2 ternary cathode materials for improved electrochemical performance

LiNi0.65Co0.15Mn0.2O2 (NCM) has some advantages of high specific capacity, low cost, and environmental friendliness, but its high nickel content leads to serious cationic mixing and poor cycling and rate performance. The N doping LiNi0.65Co0.15Mn0.2O2 (NCM-x%N) is prepared by co-precipitation method. It is indicated by various representational means that N doping can reduce the particle size, effectively inhibit the cationic mixing degree, and increase lattice spacing. The means can improve the diffusion rate of lithium ions, among which N doping LiNi0.65Co0.15Mn0.2O2 (NCM-3%N) of x = 3 has the best electrochemical performance. After 100 cycles at 0.1C, the specific discharge capacity was 137.8 mA·h·g−1 (85.80 % capacity retention rate), which is 15.87 % higher than other NCM. The magnification performance is tested at 0.1C, 0.2C, 0.5C, 1C, and 2C. After 25 cycles, the capacity retention rate of NCM-3%N was 92.1 %, 11.11 % higher than that of NCM. Reaction kinetics showed that NCM-3%N has a lithium-ion diffusion coefficient that is higher than NCM.

Boosting the potassium storage property of spongia-like copper phosphide anode via nano-in-micro construction

Metal phosphides (MPs) show great promise as anode material in potassium-ion batteries (PIBs) owing to their cost-effectiveness and high theoretical capacity. Despite that, MPs anode usually manifests inferior poor cyclability as a result of dramatic volume fluctuation during discharge–charge cycling. Herein, a scalable salt template-assisted spray-drying method is developed to fabricate the porous carbon microspheres wrapped CuP2 nanoparticles (p-CuP2/C) with a nano-in-micro structure. The combination of the CuP2 nanoparticles, large meso-porous carbon microspheres can simultaneously offer plenty of reactive sites, promote electrolyte penetration, and maintain structural integrity. Additionally, the proposed synthesis strategy is suit for the industrial manufacture. As an anode for PIBs, the p-CuP2/C anode presents a high reversible capacity (494 mAh/g at 0.05 A/g), excellent cycling stability (a capacity degradation rate of 0.04 % per cycle during 2000 cycles at 2 A/g), and superior rate capability (244 mAh/g at 2 A/g). More impressively, pairing with a potassium Prussian blue cathode, the potassium-ion coin cell shows an excellent cycling lifespan with 87.1 % capacity retention after 200 cycles at a current density of 0.1 A/g, the assembled pouch cell also maintains stable cycling at 0.3 A/g over 80 cycles. This research could offer a facile approach to develop other advanced anodes with industrial practicability for alkali ion batteries.

Long-acting electrochemical lithium-recovery from original brine using super-stable spinel lithium manganate oxide

with the unprecedented demand for raw lithium, the spinel LiMn2O4 has been widely studied for electrochemical Li-recovery from salt-lake brines, but its industrialization is hindered by the poor cyclability induced by manganese dissolution and Jahn-Teller distortion within octahedral structure. In this work, Cr-doped and carbon-coated LiMn2O4 (C-LMO-Cr) electrodes prepared via coprecipitation-calcination method are employed to improve cycling stability and lithium selectivity for electrochemical Li-recovery. The results confirm the C-LMO-Cr electrode exhibits super-high retention rate of 98.76 % and 95.70 % of the initial capacity (27 mg·g−1) after 300 and 500 cycles, respectively. The carbon buffering on the C-LMO-Cr surface effectively impedes the initial manganese dissolution with the enhanced charge transfer. Moreover, the structural evolution from Raman/XPS analysis and theoretical calculations confirms that the shrinking lattice of the carbon-buffering LMO-Cr enhances Li+ selectivity and Li+ migration. When assembled in a hybrid capacitive deionization (HCDI) device, the optimal C-LMO-Cr electrode displays high adsorption capacity of ∼21 mg·g−1, moderate energy consumption of 13 Wh·mol−1(Li+) with a remarkable increase in Mg/Li ratio from 1.67 to 158 in the original brine from Jiezechaka. Therefore, these results demonstrate a promising potential of C-LMO-Cr electrodes for long-acting electrochemical lithium-recovery from original brines.

Regulating Water Activity and Solvation Structure via Zwitterion‐Enhanced Polymer Electrolyte for Long‐Life Zn‐Ion Hybrid Capacitors with Low‐Temperature Applicability

AbstractThe development of aqueous Zn‐based energy storage systems is plagued by poor cyclability and limited operating temperatures caused by Zn anode issues and highly active water. Herein, a frost‐tolerant hydrogel electrolyte (PABCHE) promoted by hydroxyl‐rich β‐cyclodextrin (β‐CD) and zwitterionic betaine (BA) additives is fabricated in situ to protect Zn anodes and enhance low‐temperature adaptability. Both additives synergistically disrupt the hydrogen‐bonding network between water molecules to remarkably reduce the freezing point of PABCHE and alleviate water‐associated side effects. Zwitterionic BA constructs ion‐migration channels and regulate Zn2+ solvation structure, promoting uniform and rapid transport of Zn2+. Additionally, PABCHE renders the Zn2+ homoepitaxially depositing along the (002) plane to achieve dendrite‐free Zn anodes. As a result, versatile PABCHE enables Zn//Zn cells to cycle stably for 1100 and 3600 h at 20 and −20 °C, respectively. Furthermore, the Zn‐ion hybrid capacitors optimized by PABCHE deliver favorable cyclability over 30000 cycles at 20 °C (with a capacity retention of 81.8%) and −20 °C (with a capacity retention of 84.2%). Additionally, PABCHE can be applied as a flexible strain sensor for real‐time monitoring of physiological activities. This work offers valuable insights for developing antifreeze hydrogel electrolytes toward applications of dendrite‐free low‐temperature Zn‐based devices and strain sensors.

Surface engineering of TiSiO4 nano-coating for high-voltage nickel-rich ternary cathodes: An approach to improve cyclic performance

In recent years, layered ternary transition metal oxides with a high nickel content have gained substantial attention as a potential positive electrode material for lithium-ion batteries. However, its poor rate capability, cyclability, and capacity retention at high working voltages limit its use in commercial lithium-ion batteries. To overcome these challenges, we synthesize a cost-effective wet-chemical deposition of novel TiSiO4 nano-coatings over the surface of LiNi0.83Mn0.06Co0.11O2 (NMC-83). X-ray diffraction and electron microscopy confirm the presence of a coating and verify that the deposition process did not alter the crystallinity and morphology of the NMC-83 particles. In addition, during cycling, it completely protects NMC-83 with enhancements in hexagonal phase transitions between H2 and H3, resulting in excellent cycling stability at upper cut-off voltages. Likewise, when the amount of coated material is equal to 1 wt%, it provides faster ion kinetics and a stable electrode-electrolyte interface. The 1 wt% TiSiO4 coating provides 35 % retention after 250 cycles at a 0.5C rate, while the pristine NMC-83 shows only 13.7 %. From postmortem analysis, the 1 wt% TiSiO4-coated NMC-83 cathode maintains its stable polycrystalline nature compared with pristine NMC-83. Thus, this novel TiSiO4 nanocoating has significant implications for developing high-performance rechargeable batteries for energy applications.

Role of Halogen Elements in Conductivity and Electrochemical Stability of Sulfide Based Solid Electrolytes

All-solid-state batteries (ASSBs) are a promising candidate for future energy storage technology with better safety and higher energy density [1]. Safety of solid state batteries come from solid electrolytes used instead of organic liquid electrolytes in conventional Li-ion batteries. The various types of solid electrolytes have already been reported for SSBs which can be divided into oxides, sulfides, halides and polymers based on their properties, advantages and disadvantages [2]. Among them, sulfide based solid electrolytes have advantages over other due to high conductivity and ductile nature of sulfides [3]. The discovery of Li10GeP2S12 solid electrolyte called LGPS structured sulfide electrolyte have shown great potential to replace liquid electrolyte as ionic conductivity of LGPS was found 1.2×10-2 S cm-1 at room temperature comparable to the conductivity of organic liquid electrolyte [4]. However, Li10GeP2S12 electrolyte suffers with poor cyclability in solid state batteries due to reduction of Ge+4 ions to Ge0, and instable against lithium metal anode [5, 6].The solid electrolytes (SEs) with high conductivity and better stability against lithium metal are most important requirements for successful commercialization of solid state battery (SSB) technology. Therefore, in the search for new SEs with above mentioned qualities, halogen elements (Cl, Br, I) are explored in Li-P-S-O system to prepare Li10GeP2S12 (LGPS) structured SEs. In all prepared SEs, LPSOBr and LPSOI compositions show highest conductivities of 0.55 mS cm-1 and 0.67 mS cm-1 at 25 °C. The phase identification of newly synthesized solid electrolytes is done by X-ray diffractometer technique along with Rietveld refinement analysis. The conductivity of prepared solid electrolytes is determined by electrochemical impedance spectroscopy. These similar compounds also show superior stability against lithium metal in symmetric cells (Li/Ses/SE) as well as in full SSB cells (NCA/SEs/graphite) tested with LiNi0.8Co0.15Al0.05O2 cathode and graphite anode. These compounds also show 5 times higher stability in ambient environment conditions as compared to non-doped LPSO compound.

Operando X-Ray CT Analysis of Silicon/Solid Electrolyte Mechanical Interface of All-Solid-State Battery during Charging and Discharging Reaction

Silicon has a theoretical capacity about 10 times that of graphite, so it is expected to be one of the next-generation anode materials to further increase the capacity of batteries. However, silicon has a large volume change during charging and discharging, which result in poor cyclability. Although morphological change of silicon has been shown in a lot of previous studies, most of them are ex-situ observations using electron microscopes such as SEM and are two-dimensional observations1). Moreover, many previous studies target liquid battery. It is necessary to understand the expansion and shrinkage mechanism of silicon to improve all-solid-state battery performance using silicon anode. Synchrotron X-ray computed tomography (X-ray CT) is a technique that can measure the internal structure of a battery in three dimensions with micrometer-order spatial resolution in a short time. In addition, operando X-ray CT measurement is possible under charging and discharging in an all-solid-state battery2). In this study, we analyzed that morphological changes of silicon during charging and discharging by operando X-ray CT measurements.We used LiNi1/3Co1/3Mn1/3O2 (NCM), Li6PS5Cl (LPSCl) and acetylene black (AB), which were mortar-mixed in a mass ratio of 1:1:0.1 as the cathode composite material, and Si, LPSCl and AB in a mass ratio of 1:2.78:0.42 as anode composite material. Si｜LPSCl｜NCM all-solid-state cells were assembled. X-ray CT measurements at SPring-8 BL20XU using 20 keV X-rays while performing constant current charge/discharge measurement at 2.3×10-3 A cm-2. The pixel resolution was 0.5 µm. A silicon particle was extracted from the X-ray CT images obtained from X-ray CT measurements to observe the morphological changes of silicon during charging and discharging reaction. Then, change of the silicon volume and the contact area fraction of silicon particle and LPSCl solid electrolyte were calculated.Volume expansion was observed with lithiation of silicon and volume shrinkage with delithiation of silicon. As the lithiation process, silicon density decreased, and silicon was observed to be darker. As the delithiation process, cracks appeared in the silicon particle as the expanded silicon shrank. In addition, the silicon/solid electrolyte interface changed so that the silicon formed shell voids at the surface of silicon particles. This indicates that the plasticity of the LPSCl solid electrolyte cannot follow the form change of the interface. However, shell voids in the interface were formed for all directions, but some parts remained in contact area between the silicon particle and the solid electrolyte. After the second cycle of lithiation, cracks in the particle and the voids in the interface between the silicon particle and the solid electrolyte that had been formed due to the shrinkage of silicon as the delithiation disappeared by the re-lithiation. However, the re-delithiation caused cracks in the particle in the same area and formed shell voids in the interface again. Moreover, as the second delithiation process, the number of cracks in the particle increased compared with that as the first delithiation. This suggests that the number of cracks in the particle increases as silicon repeated lithiation and delithiation, and so silicon is miniaturized. In addition, a correlation was confirmed between the silicon volume change and the contact area fraction change. After the first cycle, the volume didn’t return to pristine silicon volume and the contact area fraction was reduced compared to pristine silicon. The isolation of the silicon particle from the solid electrolyte interface is suggested to be one of the factors causing the poor cycle performance because of the lithium ion reaction path is limited.1) T. Li, J. Y. Yang, S.G. Lu, H. Wang and H. Y. Ding, Rare Metals, 32, 299-304 (2013).2) Y. Sakka, H. Yamashige, A. Watanabe, A. Takeuchi, M. Uesugi, K. Uesugi and Y. Orikasa, J. Mater. Chem. A, 10, 16602–16609 (2022).

Effect of Silicate Addition on ZnO Formation during Zn Discharging Process

Rechargeable zinc batteries have been attracting extensive attention as promising candidates for next-generation energy storage, owing to their intrinsic safety, mature recycling processes, low material cost and high theoretical energy density.[1] Nevertheless, there are still several issues holding back the development of zinc batteries, such as the capacity loss due to Zn passivation and poor cyclability caused by Zn dendrite formation. [2] In the past few years, efforts have been made to improve the performance of zinc batteries, among which electrolyte modification with additives is the most widely used. [3] For further development of zinc batteries towards practical application, it is also essential to deepen the understanding of chemical state changes in a working Zn electrode. In our previous work, Zn dissolution−passivation behavior with ZnO formation during Zn discharging process has been systematically elucidated via in-situ analysis. [4] Herein this work, through comparative studies with silicate addition in the electrolyte, the correlation between ZnO formation and the discharging performance of Zn anodes is further clarified, shedding new insights into further optimization of zinc batteries.Firstly, various electrolyte additives were evaluated during Zn discharging at a current density of 40 mA/cm2. As a result, potassium silicate addition with an optimum concentration of 100 mM effectively enhanced the discharge capacity of Zn anode. Effects of silicate addition on Zn discharging process were then further investigated. After 500 s of discharging, ZnO layer with a thickness around 7 um is formed on Zn anodes, which is attributed to the dehydration of supersaturated zincate ions. [4] It is observed that as-formed ZnO petals turned from sharp to round with silicate addition. Moreover, a porous ZnO layer was formed with silicate addition, while a compact one was obtained without any additives. Accordingly, it is assumed that silicate may form adsorption or coordination with ZnO particles, leading to morphology and porosity changes in ZnO.Further analyses were carried out to verify whether the chemical state of ZnO changes with silicate addition. The TEM-EDS mapping result and XPS depth profile indicate that Si is uniformly distributed within the ZnO layer. Moreover, the presence of Si-O bond is confirmed, along with both Zn 2p 2/3 and O 1s peak shifts towards higher binding energy side. Accordingly, the coordination between silicate and ZnO via the formation of Si-O-Zn bridge is suggested, which is also supported by the DFT calculation result, as a stable existence of silicate on ZnO can be achieved.On the other hand, it is noticed via XRD and HRTEM characterization that the crystallite size of ZnO became smaller with silicate addition. Moreover, ZnO formed with silicate addition presented lower crystallinity with higher defect contents, as evidenced by Raman spectra. Given the above, it is considered that silicate modulates the electronic structure of ZnO molecules via the Si-O-Zn bonding, thereby suppresses ZnO crystal growth and particle aggregation, which eventually contributes to a loose ZnO structure that can maintain the activity of Zn anodes. With the discussion of ZnO formation herein, we hope this work may open a new avenue for developing high-performance zinc batteries.AcknowledgementsThis study was supported by the Research and Development Initiative for Scientific Innovation of New Generation Batteries (RISING) Projects, RISING3 [JPNP21006], commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.[1] P. Ruan et al., Angew. Chem., 2022, 134, e202200598[2] W. Shang et al., Energy Storage Mater., 2020, 31, 44–57[3] S. Guo et al., Energy Storage Mater., 2021, 34, 545–562[4] T. Wang et al., Energy Environ. Mater., 2023, 0, e12481

Affecting the Electropolymerization of Aniline with Permanent Magnets

As portable electronics become more ubiquitous, the demand for different electrochemical energy storage (EES) systems grows. Conductive-polymer-based supercapacitors are an emerging type of EES device promising for their rapid charging and discharging, and among these, polyaniline (PANI) is favored for the ability to deposit it electrochemically from aqueous solutions of monomer. Despite this advantage, supercapacitors fabricated with PANI exhibit poor energy density and cyclability compared to other supercapacitors. In this work, it is shown how a permanent magnet can be applied to affect this electropolymerization, increasing the capacitance of the resultant polymer film by over 70% and increasing its cyclability more than ten-fold. The use of a permanent magnet allows enhancement of the process without the use of any chemical additives or additional energy input, such as from heating, excessive overpotentials, or mechanical stirring. The magnet influences the electropolymerization primarily through the magnetohydrodynamic (MHD) effect, but this work shows that the effect of the magnetic field exceeds that of mechanical stirring. Furthermore, evidence is presented that the influence from the magnet goes beyond forced convection from the MHD effect.

Grain Analysis of NCM Cathode Materials by ASTAR Technique and Its Effect on Battery Performance

Lithium-ion batteries (LIBs) are one of the most promising energy storage systems for portable electronic devices, electric vehicles, and renewable energy systems. Among the various cathode materials for LIBs, nickel cobalt manganese (NCM) oxide has attracted considerable attention due to its high specific capacity, good cycling stability, and appropriate cost for commercialization. However, Ni-rich NCM (Ni >80%) showed poor cyclability and huge gas evolution because of surface instability.Single crystal NCM has been suggested as a solution to these issues due to its excellent properties. However, it is difficult to quantify the degree of single crystallinity because it is so far subjective. In this study, we employed ASTAR technique (transmission electron microscopy combined with electron backscatter diffraction) to investigate the microstructural features of NCM cathode materials. Our ASTAR analysis showed that NCM cathode materials consist of complex grain and grain boundary structures with varying orientations and sizes. By analyzing the grain size and its morphology, we were able to define the single crystallinity of NCM cathode materials, including the poly NCM and single crystal NCM particles.Furthermore, we found that the grain size and its distribution significantly affects the battery performance and lifespan of NCM cathode materials. Specifically, the poly NCM particles exhibited a larger grain boundary and surface area compared to the single crystal NCM particles. The poly NCM particles also showed a faster DC-IR increase and a shorter lifespan than the single crystal NCM particles, indicating that the grain size has a critical influence on the battery performance and lifespan of NCM cathode materials.Our results provide insights into the design and optimization of NCM cathode materials for next-generation LIBs. By controlling the grain size and its distribution of NCM cathode materials, it is possible to enhance the battery performance and lifespan. Therefore, our study highlights the importance of understanding the microstructural features of NCM cathode materials for developing high-performance and stable LIBs.

(Invited) Stabilizing the Electrodes and Interfaces in Lithium-Sulfur Batteries

As the electrification of transportation sector and grid storage of electricity produced from renewable sources like solar and wind are rapidly evolving, cost, sustainability, and supply chain challenges will become the dominant issue. Lithium-sulfur batteries offer significant sustainability and cost advantages compared to the currently used lithium-ion batteries as sulfur is abundant and inexpensive and offers an order of magnitude higher capacity than the oxide cathodes. However, the commercialization of lithium-sulfur batteries is met with a few challenges, such as poor cycle life in practical cells. These challenges originate from the poor electronic and ionic conduction in sulfur and its discharged products, polysulfide shuttle, and poor cyclability of lithium-metal anode. To overcome some of these difficulties, generally a large amount of conductive carbon and liquid electrolyte are added to the cell; they enhance the cycle life, but drastically lower the practical energy density and make the lithium-sulfur batteries uncompetitive with lithium-ion batteries. To overcome the above challenges, this presentation will focus on optimizing sulfur and lithium sulfide cathodes, incorporation of electrocatalysts into the cathode to enhance sulfur redox, development of advanced electrolytes, incorporation of additives into the cathode and electrolyte to stabilize the cathode-electrolyte and anode-electrolyte interfaces, anode-free cells that eliminate the handling of thin lithium-metal foils, while keeping the sulfur loading and electrolyte/sulfur ratio at a practically accepted level. The improvements achieved and the mechanisms involved in the performance improvement will be discussed based on in-depth characterization data obtained with time-of-flight secondary ion spectrometry (TOF-SIMS), x-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) spectroscopy, etc.

Immobilization and Catalytic Conversion of Polysulfide by In-Situ Generated Nickel in Hollow Carbon Fibers for High-Rate Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are considered promising energy-storage systems because of their high theoretical energy density, low cost, and eco-friendliness. However, problems such as the shuttle effect can result in the loss of active materials, poor cyclability, and rapid capacity degradation. The utilization of a structural configuration that enhances electrochemical performance via dual adsorption-catalysis strategies can overcome the limitations of Li-S batteries. In this study, an integrated interlayer structure, in which hollow carbon fibers (HCFs) were modified with in-situ-generated Ni nanoparticles, was prepared by scalable one-step carbonization. Highly hierarchically porous HCFs act as the carbon skeleton and provide a continuous three-dimensional conductive network that enhances ion/electron diffusion. Ni nanoparticles with superior anchoring and catalytic abilities can prevent the shuttle effect and increase the conversion rate, thereby promoting the electrochemical performance. This synergistic effect resulted in a high capacity retention of 582 mAh g-1 at 1 C after 100 cycles, providing an excellent rate capability of up to 3 C. The novel structure, wherein Ni nanoparticles are embedded in cotton-tissue-derived HCFs, provides a new avenue for enhancing electrochemical performance at high C rates. This results in a low-cost, sustainable, and high-performance hybrid material for the development of practical Li-S batteries.

Reorganizing Helmholtz Adsorption Plane Enables Sodium Layered-Oxide Cathode beyond High Oxidation Limits.

Sodium layered-oxides (NaxTMO2) sustain severe interfacial stability issues when subjected to battery applications. Particularly at high potential, the oxidation limits including transition metal dissolution and solid electrolyte interphase reformation are intertwined upon the cathode, resulting in poor cycle ability. Herein, by rearranging the complex and structure of the Helmholtz absorption plane adjacent to NaxTMO2 cathodes, the mechanism of constructing stable cathode/electrolyte interphase (CEI) to push up oxidation limits is clarified. The strong absorbent fluorinated anions replace the solvents into the inner Helmholtz plane, thereby reorganizing the Helmholtz absorption structure and spontaneously inducing anion-dominated interphase to envelop more active sites for layered oxides. More importantly, such multi-component CEI proves effective for the long-term durability of a series of manganese-based oxide cathodes, which achieves a 1500-cycles lifetime against high oxidation voltage limit beyond 4.3V. This work unravels the key role of breaking high-oxidation limits in attaining higher energy density of layered-oxide systems.

Tailoring the Periphery Aliphatic Group of Cathode Organosulfide for Rechargeable High‐Performance All‐Solid‐State Lithium Battery

Organic cathode materials exhibit higher energy storage capacity, their poor cyclability due to dissolution in liquid organic electrolytes remains a challenge. However, recently, the electrochemical behavior of organopolysulfides incorporating N‐heterocycles unveils promising cathode materials with stable cycling performance. Herein, the integration of organosulfides salt as cathodes with solid electrolytes, exemplified by sodium allyl(methyl)carbamodithioate and sodium diethylcarbamodithioate with a polymer solid electrolyte of polyethylene oxide and LiTFSI, addresses the poor electrochemical stability of organic electrodes. Comparative analysis highlights sodium allyl(methyl)carbamodithioate's superior electrochemical performance and stability compared with sodium diethylcarbamodithioate, emphasizing the efficacy of periphery aliphatic modification in enhancing electrode capacity, rate performance, and electrochemical stability for organosulfide materials within all‐solid‐state lithium organic batteries. We also explore the origin of periphery aliphatic modification in these enhancing electrochemical performances by kinetic analysis and thermodynamic analysis. Furthermore, employing density functional theory calculations and ex situ FTIR experiments elucidates the critical role of the N–C=S structure in the energy storage mechanism. This research advances organic cathode design within organosulfide materials, unlocking the potential of all‐solid‐state lithium organic batteries with enhanced cyclability, propelling the development of next‐generation energy storage systems.

Copper Vanadium Oxide Yolk-Shell Microspheres with Excellent Capacitance and Cycling Performance for Electrochromic Supercapacitor.

Vanadium pentoxide (V2O5) is considered a promising material for electrochromic supercapacitors due to its rich color transitions and excellent electrochemical capacity. However, V2O5 exhibits low electrical conductivity, and its volume changes dramatically during charge-discharge cycles, leading to structural collapse and poor long-term cyclability. These issues have hindered the development and application of V2O5. In this study, copper vanadium oxide yolk-shell microspheres (CVO) were synthesized through a one-step solvent heat treatment with an annealing process. With the doping of copper element, the capacitance, conductivity, and cyclic stability of CVO microspheres were significantly enhanced. Subsequently, the sphere-wire network structure was formed by blending Na2V6O16·3H2O nanowires (NVO), resulting in the formation of CVO/NVO composites. The three-dimensional sphere-wire network efficiently facilitates the acquisition of additional redox sites and strengthens the material-to-substrate bonding. Under the combined influence of these favorable factors, CVO/NVO achieved a high specific capacitance of 39.2 mF cm-2, with a capacitance retention of 84% after 7500 cycles at a current density of 0.7 mA cm-2. The fully inorganic solid-state electrochromic supercapacitor (ECSC), assembled on the basis of CVO/NVO, demonstrates a vivid and clearly distinguishable color change (ΔE* = 37). Even more impressive is the energy storage capacity (18.4 mF·cm-2) and the cycling stability (up to 89% retention after 10,000 cycles) exhibited by the devices. These key performances are superior to those of most of the previously reported V2O5-based ECSCs, opening a promising avenue for the development of V2O5-based electrochromic energy storage devices.

Revealing the potential of a C6BN/black phosphorene nanocomposite as an anode material for sodium-ion batteries by atomistic simulation: DFT and AIMD

Black phosphorus (BP) has recently been regarded as a promising anode for sodium-ion batteries (SIBs) owing to its high storage capacity, rapid Na mobility in its lamellar structure, and low redox potential. However, its poor cyclability due to structural instability hampers its further implementation in SIBs. Here, we propose to design a novel two-dimensional nanocomposite by vertically stacking a C6BN sheet on a black phosphorene layer (C6BN/Black-Pn). Atomistic simulations by the van der Waals corrected density functional theory method were conducted to assess the suitability of the designed C6BN/Black-Pn model as a potential anode in SIBs. Benefiting from C6BN's electronic and chemical features, Black-Pn's band gap in C6BN/Black-Pn is diminished to 0.14 eV, which disappears and indicates metallic character upon sodiation. Additionally, the optimized Na adsorption energy within the nanocomposite is decreased to −2.06 eV, compared to −1.76 eV in pure Black-Pn and −0.98 eV in C6BN, with a modest diffusion barrier of 0.23 eV. A maximal theoretical capacity of 568.77 mAh/g and a low potential of 0.48 V are predicted for the nanocomposite. The above evaluation of C6BN/Black-Pn electrode for SIBs may provide better insights into adopting a physical approach to address BP electrochemical failures for advanced energy storage.

Manipulation of Linked Phosphorus Chemistry to Enhance the Battery Performance of Phenazine‐Based Porous Polymers

AbstractOrganic p‐type cathodes have captured increasing attention for lithium‐organic batteries due to their high voltage output. However, because of the low electronic and ionic conductivity, the p‐type organic electrode materials often show sluggish reaction kinetics and hence low capacities and poor cyclability. In this work, three conjugated polymers (Pz‐TPPO, Pz‐TPPS, and Pz‐TPP) based on p‐type phenazine linked with triphenyl phosphine are reported with different chemical modifications of phosphorus atom. Through oxidation and sulfuration of phosphorus atoms, the electron‐accepting property strength is increased, resulting in higher electronic conductivity of Pz‐TPPO and Pz‐TPPS. It is also found that the P═O unit in Pz‐TPPO exhibits stronger Li+ coordination, which can bring anions into close proximity to the redox centers, further improving the anion shuttling during charge and discharge. All these lead to the best lithium‐organic battery performance of Pz‐TPPO, such as high voltage output (3.1–3.9 V), high reversible specific capacity (149 mAh g−1 at 0.2 A g−1) and excellent cycle stability. The potential application has also been demonstrated in Pz‐TPPO//graphite full battery. This work provides a novel strategy for designing donor–acceptor (D–A) conjugated polymer by simple phosphorus modification toward high‐performance organic batteries.

Electric field induced molecular orientation to construct the composite polymer electrolytes with vertically aligned ion diffusion pathways for stable solid-state lithium metal batteries

Fabricating flexible composite polymer electrolytes (CPEs) with vertically aligned ion transport pathways is necessary for the application of solid-state lithium metal batteries (LMBs), yet the orientation of polymer matrix usually is disorder, thus the improvement in ionic conductivity is unsatisfied. Herein, we develop a simple electric field induced molecular orientation strategy to fabricate the flexible CPEs with vertically aligned ion transport pathways. Driven by direct current (DC) electric field (e.g. 1.5 MV m−1), the polar 15C5-Li+ dipoles and monomer molecules are oriented regularly and cured to form flexible three dimension (3D) cross-linked structure. As a result, numerous vertically-aligned ion transport pathways have been generated in the vertically oriented arrangement CPEs, thus presenting highly enhanced ionic conductivities, mechanical strength and superb inhibition ability to lithium dendrite growth. When used as CPEs for Li||LiFePO4 (LFP) batteries, the vertically oriented CPEs exhibit excellent rate and long-term cycle stability with a reversible discharge capability of 124.9 mAh g−1 after 350 cycles at 1C and 60 °C. However, the randomly oriented CPEs deliver much poor cycle and rate performance at the same conduction. It can also be compatible with NCM811|Li batteries at 30 °C. Therefore, our simple DC electric field induced molecular orientation strategy holds a great application promise to construct the fast ion transport channels for the all-solid-state LMBs.

V-Doped CoSe2 Nanowire Catalysts in a 3D-Structured Electrode for Durable Li-S Pouch Cells.

Lithium-sulfur (Li-S) batteries have high theoretical energy density and are regarded as a promising candidate for next-generation energy storage systems. However, their practical applications are hindered by the slow kinetics of sulfur conversion and polysulfide shuttling. In particular, large-scale pouch cells show much poor cyclability. Here, we develop a high-efficiency catalyst of V-doped CoSe2 by studying the binary CoSe2-VSe2 system and confirming its effectiveness in accelerating polysulfide conversion. The coin cell tests reveal an initial capacity of 1414 mAh g-1 at 0.1 C and 1049 mAh g-1 at 1 C and demonstrate 1000 times cyclability with a decaying rate of 0.05% per cycle. Furthermore, the assembly and construction of pouch cells were optimized with monolithic three-dimensional (3D) electrodes and a multistacking strategy. Specifically, a 3D metallic scaffold (3MS) was developed to host V-doped CoSe2 nanowires and sulfur. In addition, Janus microspheres of C@TiO2 were synthesized to capture polar polysulfides with their polar part of TiO2 and adsorb nonpolar sulfur with their nonpolar part of carbon. By integrating with 3MS, C@TiO2 microspheres can block all ion channels of 3MS and only allow Li ions in and out. These integral designs and monolithic structures enable multistacking pouch cells with high cyclability. A high-loading pouch cell was demonstrated with a total capacity of 700 mAh. The cell can be cycled for 70 times with a capacity retention of 65.7%. In brief, this work provides an integral strategy of catalyst design and overall 3D assembly for practical Li-S batteries in a large pouch cell format.