Capacity Retention Rate Research Articles

The Cathode-Electrolyte Interface Constructed with Antioxidant Ascorbic Acid Guides LNMO to Achieve Stable Cycling Under High Voltage Conditions.

LiNi0.5Mn1.5O4 (LNMO) is considered one of the most promising cathode materials for high-energy-density lithium-ion batteries (LIBs). However, free-radical-induced carbonate electrolyte decomposition is a key factor hindering the improvement of battery stability. Inspired by the antioxidative properties of ascorbic acid (AA) in scavenging free radicals, the addition of AA during the electrode fabrication process can effectively terminate free radical chain reactions within the cycling of LNMO. This action prevents severe electrolyte decomposition, thus stabilizing the cathode-electrolyte interface (CEI) and ultimately enhancing battery stability. The results demonstrate that LNMO||Li half-cell with the addition of AA show significantly improved cycling performance after 1000 cycles at 1 C, with a high capacity retention rate of 87.4%, surpassing the 43.6% retention rate achieved by batteries using PVDF alone as a binder. This work introduces an efficient and straightforward strategy for designing functional additives to stabilize phase interfaces, offering an economically efficient choice to enhance the electrochemical performance of the LNMO.

Internal Doping and Surface Coating: Mn/La-HCF @ Fe-HCF Composites as High-Performance Cathode Materials for Sodium-Ion Batteries

Manganese-based Prussian blue analogue (Mn-HCF) has outstanding advantages such as a high discharge platform, high discharge capacity and high energy density compared with other PB and PBAs, which is a very valuable cathode material for sodium-ion batteries. However, the rapid decrease in capacity in the cycle process by the Jahn–Teller effect caused by [Formula: see text] is the main obstacle to the commercialization of Mn-HCF. In this work, Mn/La-HCF @ Fe-HCF was synthesized by doping La element into the Mn-HCF phase to suppress the Jahn–Teller effect of Mn ions and coating the Fe-HCF phase outside to protect the Mn-HCF phase from electrolyte corrosion. Benefiting from the inhibition of the Jahn–Teller effect of [Formula: see text] by the abundant electronic energy level structure of La element and the protection of Fe-HCF phase relative to Mn-HCF phase, the initial discharge capacity of Mn/La-HCF @ Fe-HCF can reach 135.6 mAh [Formula: see text] at current density of 0.1 C, and it still has a high discharge capacity of 112.2[Formula: see text]mAh [Formula: see text] at current density of 5 C. After 300 cycles at a current density of 2 C, the reversible capacity of 117.6[Formula: see text]mAh [Formula: see text] is maintained (capacity retention rate is 86.1%). The results show that this method of internal doping and outsourcing can greatly improve the electrochemical performance of Mn-HCF, and provide feasible ideas for the commercialization of Mn-HCF.

Amino‐Modified Porous Aromatic Frameworks for Enhanced Lithium‐Ion Dissociation and Transport in Polymer Electrolytes

Enhancing the ionic conductivity of solid polymer electrolytes and accelerating ion transport are pivotal challenges in achieving lithium‐ion batteries with high energy density and excellent electrochemical performance. In this study, amino‐modified porous aromatic frameworks (AMPAF) are prepared. The amino group in AMPAF stabilizes the anion through hydrogen bonding to reduce the dissociation energy barrier of Li+, enabling Li+ to be more easily dissociated from lithium salts. Additionally, the abundant pores of AMPAF promote the rapid transport of Li+. The prepared quasi‐solid polymer electrolyte (AMPAF‐QSPE) exhibited a high Li+ conductivity of 7.62 × 10−5 S cm−1 and a Li+ transference number as high as 0.55, which proves the restriction of the amino group in AMPAF on the movement of anions and the ability to dissociate lithium salts. The discharge specific capacity of Li//AMPAF‐QSPE//LiFePO4 reached as high as 137 mAh g−1 at 0.2 °C, and the capacity retention rate was stable at 85% after 200 cycles. This article presents an effective attempt to enhance the overall performance of polymer electrolytes using amino‐modified PAF, offering an innovative perspective for the development of electrochemical energy storage technologies.

Effect of Fluorine Segments in Fluoropolymer Matrix on the Properties of Gel Polymer Electrolytes

AbstractPolymer quasi‐solid electrolytes have been paid widely attention in account of their outstanding advantages in safety, flexibility, viscoelasticity and film formation. Fluoropolymer is used as matrix of gel electrolytes not only has high electrochemical stability, but also facilitates the dissociation of lithium salts owning to the strong electron‐absorbing C−F groups, which makes it a very promising choice for the further development of gel electrolytes. Due to the different sites of C−F bonds, their activity is also diverse, which results in the difference of the mobility of lithium ions and the LiF composition of SEI film on the surface of lithium metal anode. As a result, distinct fluorine‐containing gel polymer electrolytes are prepared by in‐situ polymerization of two different monomers, HFMA and TFMA. Compared with −CF3 on terminal group in TFMA, the gel electrolyte polymerized with HFMA whose C−F group with stronger electronegativity is at the intermediate carbon site, as polymer matrix has better performance. The ionic conductivity achieves 7.02×10−3 S cm−1 at room temperature, and the assembled batteries have a capacity retention rate of 91 % after 200 cycles of 1 C. Our research has laid a solid theoretical foundation for the further development of quasi‐solid electrolyte.

Zr4+-doped sodium manganese oxide: enhanced electrochemical performance as a cathode in sodium ion batteries.

Sodium manganese oxides are regarded as a valuable class of cathode materials for sodium-ion batteries. By varying the stoichiometry of Na, Mn and O, it is possible to obtain layered, tunnel and spinel type structures, which can withstand the electrochemically-triggered sodiation-desodiation process. In this work, we report the electrochemical performance of Na4Mn2O5, a sodium-rich manganese oxide, which has been previously reported to suffer from structural instability due to the Jahn-Teller distortion of the Mn3+ ion. It was observed that the Na4Mn2-xZrxO5 (x = 0.1) cathode delivered a discharge capacity of ∼203 mA h g-1 post 250 cycles with a capacity retention rate of ∼82.8% on doping with Zr4+ ions. The improvement in cycling ability and rate capability is attributed to the enhanced structural stability and improved electronic conduction brought about by the substitution of Mn3+ by Zr4+ in Na4Mn2O5. Density functional theory-based studies were conducted, which adequately support the obtained results.

Modified poly(vinylidene fluoride) polymer binder enables ultrathin sulfide solid electrolyte membrane for all-solid-state batteries

All-solid-state batteries (ASSBs) employing high-ionic-conductivity sulfide solid electrolytes (SEs) are the most promising next-generation batteries. Scalable fabrication of sulfide SE membranes is the priority for mass production of ASSBs. However, due to the poor chemical stability of sulfide SEs, the wet-slurry-based preparation of sulfide SE membranes is still hindered by limited choices of solvent-binder systems. Herein, we reported a modified poly(vinylidene fluoride) (M-PVDF) binder to achieve environment-friendly fabrication of sulfide SE membranes. Copolymerization is firstly performed on the widely-used PVDF binder to decrease crystallinity, which facilitate excellent solubility in the isobutyl isobutyrate-based slurry. Utilizing this efficient M-PVDF binder, the sulfide SE membrane achieves a high ionic conductivity of 2 mS cm−1 at 25 °C, an ultra-thin thickness of 26 μm, and good flexibility. The resulting ASSBs exhibit excellent rate performance with 53.51 % capacity utilization ratio at 5C. The ASSB also maintains high capacity retention rates of 96.9 % after 350 cycles under 0.5C at 25 °C and 87.8 % after 1000 cycles under 5C at 45 °C. This work can facilitate the non-toxic wet-slurry-based manufacturing of sulfide SE membrane, helping to promote the commercialization of ASSBs.

Wide-temperature zinc-iodine batteries enabling by a Zn-ion conducting covalent organic framework buffer layer

Aqueous zinc-iodine batteries (ZIBs) are attractive energy storage devices owing to their safety and low cost, but polyiodide shuttling and poor wide-temperature operation limit their scalability. Herein, a sulfonated zinc-grafted covalent organic framework (COF) (denoted TpPa-Zn) was designed and served as the buffer layer on the surface of glass fiber (GF) to enhance ZIBs’ performance. The TpPa-Zn structure exhibits single zinc-ion conductivity, with its nanopores and sulfonic acid groups effectively suppressing polyiodide shuttling. In-situ Raman and X-ray photoelectron spectroscopy tests revealed that the TpPa-Zn modified separator promotes polyiodide conversion, reducing self-discharge and enhancing cycle stability. The upgraded ZIBs were demonstrated with ultra-stable operation over a wide temperature ranging from 0 to 65 ℃, retaining 90.5 % and 90.7 % capacity retention rate at 65 ℃ (500 cycles) and 0 ℃ (2000 cycles), respectively. Moreover, high-iodine-loading tests demonstrated practical applicability, with a retention rate of 87 % at 3 mg cm−2 and 93 % at 5 mg cm−2. This study elucidates that the TpPa-Zn buffer layer significantly improves the temperature adaptability of ZIBs, potentially inspiring the rational design of COF-based wide-temperature batteries.

Regulating chiral nematic liquid crystal of hydroxypropyl methylcellulose coating on separator for High-Safety Lithium-Ion batteries

The conventional commercial polypropylene separator (PP) struggles to inhibit the thermal runaway triggered by dendrite short circuits, and its safety cannot meet the needs of the development of high-energy–density batteries. Herein, an easily commercializable design strategy was employed to induce the aqueous solution of natural polymer hydroxypropylmethylcellulose (HPMC) to self-assemble on the surface of the PP separator by Na2SO4, MnSO4, and Al2(SO4)3 to form the chiral nematic liquid crystal (CLC) with excellent performance, and finally the thermally stable separators (H-Na@PP, H-Mn@PP, and H-Al@PP) were obtained. Theoretical calculations and experiments demonstrate that the CLC induced by Na+, Mn2+, and Al3+ can interact with the electrolyte solvent to form a desolvation structure of Li+, which reduces the migration barrier of Li+ through the separator and accelerate the Li+ transport. Furthermore, the ordered CLC structure can ensure uniform electric field and Li+ flux. Hence, Li//LFP, Li (50 μm)//LFP, and Li//NCM811cells are assembled using these modified separators, featuring remarkable cycling stability and high Coulombic efficiency. As the result, H-Na@PP, H-Mn@PP, and H-Al@PP separators in Li//LFP cell display a high initial capacity of 141.2 mAh/g, 146.7 mAh/g and 130.7 mAh/g at 1C, respectively and stable cycling performance over 1000 cycles. Notably, the capacity retention rate remains high at 87 %, 69 %, and 59 % even after 700 cycles, respectively, which are higher than the 21 % capacity retention rate of PP separator. Meanwhile, the pouch cells equipped with these separators deliver exceptional electrochemical performance and show a lower temperature distribution without thermal runaway behavior under the Φ3 mm nail penetration test, indicating its feasibility for high-safety energy storage systems.

Effect of increasing alkali layer spacing on the performance of O3-NaNi1/3Fe1/3Mn1/3O2 cathode materials

O3-Na1-xCax/2Ni1/3Fe1/3Mn1/3O2 (NaCNFMx, x=0, 0.05, 0.1, 0.15) was prepared by doping calcium ions and replacing the sodium sites in the NaNi1/3Fe1/3Mn1/3O2 (NaNFM) material using ball milling spray. XRD, SEM and XPS results demonstrated that the calcium element was successfully embedded in the lattice. The electrochemical performance of NaCNFM0.1 is the best when the doping amount of calcium ion is 0.1. The sodium diffusion coefficient of NaCNFM0.1 cathode material after 3 cycles is 1.67×10-14 cm2/s. The first specific discharge capacity at 1C is 121.1mAh/g. Even at the high current density of 5C, the 200cycles capacity of 103.6mAh/g is much higher than NaNFM's 95.2mAh/g, and the capacity retention rate is as high as 91.5%. Ex-situ XRD and SEM analyses manifested that the moderate amount of calcium doping improved the stability of the layered structure. These results show that the cathode material has great application potential.

Enhancing Potassium‐Ion Storage through Nanostructure Engineering and Ion‐Doped: A Case Study of Cu2+‐Doped Co0.85Se with Yolk‐Shell Structure

AbstractFabricating transition metal selenide (TMSe) anode materials with rapid K+ diffusion and high‐rate performance is crucial for the advancement of potassium‐ion batteries (PIBs), yet it remains a challenge. In this study, a Cu2+‐doped Co0.85Se@N‐doped carbon anode with an optimal concentration of Cu2+‐doped and yolk‐shell structure (denoted as Cu‐Co0.85Se@NC‐2) is developed to enhance the reaction kinetics and cycling life. The Cu2+‐doped modulates the electronic structure of the Co0.85Se interface, improves the diffusion and adsorption of K+, and further promotes the charge transport efficiency, as demonstrated by theoretical calculations and experimental results. In addition, an optimal Cu2+‐doped content is identified that is conducive to achieving the best structure and electrochemical performance. Moreover, the N‐doped carbon shell effectively enhances the conductivity of the electrode and alleviates the volume change of Co0.85Se yolk during cycling. Benefiting from the above advantages, the obtained Cu‐Co0.85Se@NC‐2 anode exhibits excellent rate performance (208.1 mA h g−1 at 10 A g−1) and cycling stability (239.7 mA h g−1 at 2 A g−1 after 500 cycles, the capacity retention rate is up to 80.4%). This work integrates nanostructure engineering and ion‐doped to provide a straightforward and effective strategy for designing advanced high‐rate TMSe anodes for next‐generation PIBs.

Preparation of lignite-based porous carbon for high performance supercapacitor and the correlation between pore structures and electrochemical performance

Porous carbon exhibits considerable potential in energy storage field due to its remarkable electrical conductivity and adjustable pore structure. Nevertheless, the electrochemical performance of the material will be significantly impacted by its unreasonable pore structure. In this study, lignite was used as raw material to prepare lignite-based porous carbon by one-step activation method and the pore structure was optimized to improve its electrochemical performance and expand the utilization of low-rank coal. The results reveal that the porous carbon prepared at 600 °C has a higher specific surface area (940 m2 g−1) and a suitable pore structure (71 % mesopore), which enable adequate charge storage and fast transport of electrolyte ions, resulting in excellent electrochemical performance. In the three-electrode system, the lignite-based porous carbon exhibits a notable specific capacity of 331 F g−1 at the current density of 0.5 A g−1 and retains 96.4 % initial capacitance after undergoing 10,000 cycles. When assembled into a symmetrical supercapacitor, the device provides an energy density of 6.5 Wh kg−1 at a power density of 250 W kg−1. Even after 10,000 cycles, the capacitance retention rate is kept at 91 %, and the coulombic efficiency remains close to 100 %. These findings demonstrate that cost-effective porous carbon can be prepared by a simple route using lignite, hence exhibiting promise as electrode materials for high-performance supercapacitors.

Bamboo waste derived hard carbon as high performance anode for sodium-ion batteries

Biomass-derived hard carbon stands out as one of the most promising anode materials for advancing the commercial viability of sodium-ion batteries (SIBs). In this study, we harnessed a straightforward and eco-friendly two-step carbonization approach to fabricate high-performance hard carbon materials, ingeniously repurposing industrial bamboo waste. Concurrently, we delved into the impact of carbonization temperature on the microstructure and properties of the hard carbon derived from bamboo waste. The findings revealed that the as-prepared hard carbon at 1400 °C (HCB-1400) showcased the most desirable sodium-ion storage capabilities. The HCB-1400 material not only can deliver a substantial reversible capacity of 328.4 mAh g−1 at 30 mA g−1 in its maiden charge-discharge cycle but also display remarkable cycling stability. Moreover, the HCB-1400//Na3V2(PO4)3 full cell, when assembled, exhibited an impressive energy density of 249.25 Wh kg−1, with a capacity retention rate of 93 % after enduring 200 cycles at a current density of 1.0 C. This research underscores the potential of transforming biomass waste into high-performance hard carbon, heralding a sustainable path for SIB applications.

Hydrothermal synthesis of rGO-decorated NiMn2O4 nanoneedles for high-performance positive electrode in asymmetric supercapacitors

Pseudocapacitive electrode materials inherently have low electron conductivity, which prevents an energetic material from being fully utilised. We were able to produce effective hierarchical NiMn2O4/rGO composites, which provide an appealing solution to this issue. The composites were synthesised using a one-step hydrothermal approach. Due to the high electrical conductivity of reduced graphene oxide (rGO), the needles on plate like morphology of NiMn2O4, and the strong hold of dynamic materials to the current collector, the resulting hybrid electrodes exhibit a specific capacitance of 1628 Fg−1 at a current density of 1 Ag−1. They also demonstrate excellent rate performance and remarkable cycling stability, with a capacitance retention of 97.4 % after 10,000 cycles. In addition, the NiMn2O4/rGO//AC asymmetric supercapacitor (ASC) exhibits a peak energy density of 45Whkg−1 when operated at a power density of 3240 Wkg−1. The ASC device has an impressive ultralong cycling life, with a capacitance retention rate of 89.1 % after undergoing 10,000 charge/discharge cycles. The NiMn2O4/rGO composites provide a scalable production method and demonstrate outstanding electrochemical performance. This presents an opportunity to create innovative hybrid electrodes for enhanced supercapacitors.

Advanced Hierarchical Lithiophilic Scaffold Design to Facilitate Synchronous Deposition for Dendrite‐Free Lithium Metal Batteries

AbstractLocalized deposition behavior tends to induce the growth of lithium dendrite and hinder the the full utilization of lithium storage space, significantly impeding the practical application of 3D conductive hosts. Here, a novel synchronous deposition mode is proposed for the first time through hierarchical structure design of 3D Li host. The top‐down gradually enhanced lithiophilicity and conductivity of 3D scaffold provide sufficient driving force for Li+ to migrate downward, promoting synchronous Li deposition within the entire space of the host. Notably, the novel deposition mode has been theoretically and experimentally validated through finite element simulation and in situ optical microscopy, respectively. The meticulously designed strategy not only maximizes the utilization of the entire 3D scaffold space but also prevents the formation of Li dendrites under high current rate. Consequently, the symmetric Li//Li cell exhibits a long‐term cycling lifespan over 3700 h with a low overpotential of 15.6 mV, together with a Coulombic efficiency as high as 99.5% over 300 cycles at 3 mA cm−2. The full cell paired with LiFePO4 cathode demonstrates a cycling lifespan of 1000 cycles with a capacity retention rate of 91.6%. The proposed synchronous deposition strategy opens up a new paradigm for the design and construction of 3D hosts for dendrite‐free Li metal anode.

High Entropy Oxide Duplex Yolk-Shell Structure with Isogenic Amorphous/Crystalline Heterophase as a Promising Anode Material for Lithium-Ion Batteries.

Achieving composition and structure regulation on high entropy materials is a big challenge but will give this kind of new materials a huge boost in energy storage. Herein, a novel high entropy oxide ((CrMnFeCoNi)3O4) duplex yolk-shell structure (DYSHEO) with isogenic amorphous/crystalline heterophase are designed and successfully prepared through a simple microthermal solvothermal reaction followed by mesothermal calcination. The microthermal solvothermal reaction results in high entropy precursor with duplex yolk-shell structure, while the mesothermal calcination (annealing temperature at 450°C) realizes the precursor transformation to (CrMnFeCoNi)3O4 (DYSHEO-450) with isogenic amorphous/crystalline heterophase structure. The high entropy effect, the duplex yolk-shell structure, and the isogenic amorphous/crystalline heterophase endow DYSHEO-450 great advantages as lithium-ion battery anode including reducing ion migration obstruction, accommodating volume expansion, and alleviating the stress. Accordingly, DYSHEO-450 exhibits high capacities of 1721 mAh g-1@0.5A g-1, and 1356 mAh g-1@1 A g-1 after 500 cycles with a capacity retention rate of 90.3%. It also shows excellent performances in practical application as anode of a coin-type full cell. This work provides new ideas and directions for the structural regulation of high-entropy materials.

Effects of layered walnut NiS@NTA on hydrogen storage performance of MgH2

To investigate the effects of NiS concentration in NiS/C composites on catalytic performance and hydrogen storage performance of MgH2 particles, we synthesized nitrilotriacetic acid (NTA) chelating agent–derived composites with various NiS proportions via a hydrothermal process, labeled as NiS@NTAx (x = 0.065, 0.078, 0.091, 0.107, and 0.119, respectively). The composites exhibited a layered walnut morphology. After ball milling 5 wt% NiS@NTAx with MgH2, the resulting MgH2–5 wt%NiS@NTA0.078 composite (NiS: 83.5 wt% and C: 16.5 wt%) demonstrated the excellent performance, which could absorb 3.0 wt% of H2 at 353 K and released 3.5 wt% of H2 at 573 K within 60 min, and the intital dehydrogenation temperature was decreased to 508 K.. Undergoing 20 hydrogen absorption/desorption cycles, the composite maintained hydrogenation/dehydrogenation capacity retention rates of 97.4 % and 96.4 % with activation energies of 24.1 and 67.3kJ/mol, respectively. The in situ formation of MgS and Mg2Ni catalysts promoted electron transfer during Mg and MgH2 transformation. Moreover, as a prominent transition metal, Ni Ni element reacts with the hydrogen absorption and desorption of Mg to form Mg2Ni/Mg2NiH4, which is like a “hydrogen pump” and provides additional hydrogen diffusion channels due to more interfaces. MgS additionally functioned as a catalyst in the reaction system, improving overall reaction kinetics. Carbon additives reduced particle agglomeration, stabilized the particle size, and moderately improved hydrogen diffusion during hydrogen absorption/desorption cycles. The in situ adjustment of NiS concentration in NiS/C samples and its impacts on MgH2 hydrogenation/dehydrogenation offer insights for designing high-performance sulfide catalysts.

Regulated solvation structure and solid electrolyte interfaces via imidazolium ionic gel electrolytes with high Li-ion transference number for Li-metal batteries

Solid lithium metal batteries (LMBs) are faced with problems such as the solvation structure of lithium ion and the instability of solid electrolyte interface (SEI), which lead to poor cycling stability and anode interface damage. Here, the introduced 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([EMIM][FSI]) ionic liquid (IL) interacts strongly with Lithium salt to form a new ionic gel electrolyte (IGE) based on the poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), which facilitates the excellent Li-ion transference number up to 0.506 and improves the mechanical properties. The reconstruction of Li-ion solvation environment by [EMIM][FSI] and PVDF-HFP functional groups, as well as the formation of SEI protective layer rich in LiF and Li3N, make the IGE with excellent electrochemical properties and interfacial stability. As a result, the Li||Li symmetric batteries demonstrate outstanding cycle stability, while the LiFePO4||Li batteries exhibit a superior capacity of 154.04 mAh/g at 0.2 C, maintaining a capacity retention rate as high as 94.5 % even after 200 cycles. The results not only demonstrate a new approach to improve Li-ion transference number in IGEs, but also open a potential avenue to achieve LMBs with high performance.

Detecting and repairing micro defects in perfluorinated ion exchange membranes for redox flow batteries

Ion exchange membranes play a vital role in redox flow batteries. However, polymer membranes with a microscopic thickness of approximately 20–50 μm are susceptible to micro defects, which substantially reduces the battery's energy efficiency and cycling stability. Hence, there is a need for an effective strategy to identify and resolve membrane imperfections, which is currently missing in the literature. In this work, a pressure-retention setup and hot-pressing method are proposed and show that defective membranes can be effectively identified and resolved. For instance, a membrane with around 100-μm pinholes exhibits a low coulombic efficiency of 77.5 % at the current density of 100 mA cm−2. However, the coulombic efficiency can be raised to 96.3 % by removing the defects, thus attaining the level of the undamaged pristine membrane (96.4 %). The capacity retention rate of the vanadium redox flow batteries with the repaired membrane is 71.1 % over 100 cycles at the current density of 200 mA cm−2, close to that of the pristine membrane (72.2 %). In addition, the repaired membrane exhibits quite similar physicochemical properties to the pristine membrane from various characterizations. The proposed method represents a convenient, economical, and non-destructive membrane detecting and repairing strategy, demonstrating great potential for redox flow batteries.

APullulan polysaccharide-based flame-retardant polyelectrolyte hydrogel for high-safety flexible zinc ion capacitors

Potential safety hazards such as leakage, flammability and thermal runaway of liquid electrolytes in conventional energy storage devices have seriously hindered their further development. In this work, a flame-retardant polyacrylamide/pullulan/phytic acid (PAM/PUL/PA) hydrogel electrolyte is prepared by using PA as flame-retardant additive, PAM as main polymer chain by one-step radical polymerization method. The PAM/PUL/PA hydrogel shows good flame-retardant properties with limiting oxygen index of up to 58 %, high mechanical performance with stretch up to 1535 % and 92 kPa tensile stress. Zinc ion capacitor (ZIC) assembled with the PAM/PUL/PA hydrogel as electrolyte and separator exhibits high ionic conductivity of 22.54 mS cm−1, high specific capacity of 111.5 mAh g−1 at 0.1 A g−1 and energy density of 97.57 Wh kg−1 at a power density of 49.99 W kg−1, as well as good capacitance retention of 74.6 % even after 10,000 cycles. Furthermore, the ZIC has outstanding flexibility, the capacitance retention rate almost unchanged even after 1000 consecutive bending of deformations. These excellent properties are attributed to the hydrogen bonds easily formed by polar functional groups in hydrogels and the electrostatic interactions with metal ions. This work presented a simple and general pathway to prepare high-safety flexible energy storage devices with multifunctional properties.

Direct Regeneration of Industrial LiFePO4 Black Mass Through A Glycerol‐Enabled Granule Reconstruction Strategy

AbstractWith the increasing sales of electric vehicles, lots of spent lithium‐ion batteries (LIBs) assembled with LiFePO4 (LFP) cathodes will retire in the next few years, posing a significant challenge for their effective and environmentally‐friendly recycling. The main reason why spent LFP cathodes fail to re‐utilize lies in the lattice defects caused by lithium loss and structural defects resulting from stress accumulation. In this work, we propose an in situ granule reconstruction strategy to directly regenerate spent LFP black mass (S−BM) using glycerol in industry settings. The hydroxyl groups abundant in glycerol serves as electron donor that help reduce Fe (III) and repair Fe−Li antisite defects (FeLi). Additionally, the chelating properties of glycerol intervene with structurally disintegrated particles, inhibiting Oswald ripening effect and promoting bonding of grain boundaries to generate lamellar microcrystals with homogeneous grain size, recover their morphology and crystal structure after a facile annealing procedure. Furthermore, the regenerated LFP restores Fe−O bonds which further inhibits structural distortion and improve Li+ migration kinetics. As a result, the regenerated industrial LFP black mass (R−BM) exhibits superior lithium storage performance with a discharge capacity of 123.2 mA h g−1 after 500 cycles at 5.0 C (a capacity retention rate of 93.1 %).