Long-term Cycling Performance Research Articles

Synergistic regulation of Li deposition on F-doped hollow carbon spheres toward dendrite-free lithium metal anodes.

The notorious issues of lithium (Li) dendrite growth and volume change hinder the practical applications of Li metal anodes. LiF as a key component of the solid electrolyte interface (SEI) governs Li+ transport and deposition, yet the formation of LiF consumes the anions (PF6-/TFSI-) in the electrolyte, preventing the stable cycling of Li anodes. Herein, fluorine (F)-doped hollow carbon (FHC) was synthesized and used to construct a composite current collector with FHC as an F-rich buffer layer for modifying the Cu foil. The F content provided by FHC not only mitigates the anion (PF6-/TFSI-) consumption but also enhances the stability of SEI. The hollow structure of FHC with abundant internal space can accommodate deposited Li to relieve the volume change during cycling. Besides, the significantly improved specific surface area of the electrode effectively reduces the local current density to achieve a homogeneous Li deposition. Due to the above cooperation, the symmetrical cell of Cu@FHC-Li||Cu@FHC-Li maintains stable cycling for more than 1800 h with a hysteresis voltage of 19 mV. In addition, full cell coupling with LiFePO4 cathode delivers excellent long-term cycling and rate performance. This work provides an effective route for developing stable Li metal anodes.

Sulfur-containing polymer/carbon nanotube composite cathode materials for high-energy lithium–sulfur batteries

A sulfur-rich polymer/carbon nanotube composite cathode prepared by a facile method can achieve excellent long-term cycling performance at high current densities.

A high entropy O3-Na1.0Li0.1Ni0.3Fe0.1Mn0.25Ti0.25O2 cathode with reversible phase transitions and superior electrochemical performances for sodium-ion batteries

A high-entropy oxide cathode-Na1.0Li0.1Ni0.3Fe0.1Mn0.25Ti0.25O2 was developed featuring Li/Ti co-substitution that showcases highly reversible phase transitions, enhanced Na+-ion diffusivity and superior long-term cycling performances.

Manganese-cobalt hydroxide nanosheets anchored on a hollow sulfur-doped bimetallic MOF for high-performance supercapacitors and the hydrogen evolution reaction in alkaline media.

Nonmetallic doping and in situ growth techniques for designing electrode materials with excellent electrocatalytic activity are effective strategies to enhance the electrochemical performance. Bifunctional electrode materials for supercapacitors (SCs) and the hydrogen evolution reaction (HER) have attracted great interest due to their potential applications in green energy storage and conversion. Herein, the bimetallic MnCo LDH is anchored on a hollow sulfur (S)-doped MnCo-MOF-74 surface, forming a poplar flower-like 3D composite which is used for SCs and the HER in alkaline media. The fabricated S-MnCo-MOF-74@MnCo LDH/NF electrode exhibits a favorable specific capacitance of 1875.4 F g-1 at 1 A g-1 and steady long-term cycling performance. Moreover, the assembled HSC using S-MnCo-MOF-7@MnCo LDH/NF as the cathode material and active carbon (AC) as the anode material shows 546.4 F g-1 capacitance (1 A g-1) with a maximum energy density of 58 W h kg-1 at 14 000 W kg-1 power density. As an electrocatalyst, S-MnCo-MOF-7@MnCo LDH/NF exhibits excellent HER properties with a small Tafel slope of 128.9 mV dec-1 a low overpotential of 197 mV at 10 mA cm-2 and durable performance for 10 hours in alkaline media. The present work provides insights into understanding and designing active electrode materials for stable hydrogen evolution and high-performing supercapacitors in an alkaline environment.

Efficient sulfur atom-doped three-dimensional porous MXene-assisted sodium ion batteries.

Recently, it has been reported that MXene is a promising pseudocapacitive material for energy storage, primarily due to its intercalation mechanism. However, Ti3C2Tx MXenes face challenges, such as inadequate layer spacing and low specific capacity, which greatly hinder their potential as anode materials for sodium storage. In this study, MXene was doped with sulfur to create a three-dimensional porous structure that resulted in an increased layer spacing. The sulfur-doped porous MXene (SPM) demonstrated exceptional performance as sodium ion battery anodes, with a capacity of 335.2 mA h g-1 after 490 cycles at 2 A g-1 and a long-term cycling performance of 256.1 mA h g-1 even after 2480 cycles at 5 A g-1. It is worth noting that the porous structure formed after sulfur-doping exhibits superior sodium storage performance compared to previously reported MXene-based electrodes. This highlights the feasibility of the structural construction strategy, offering an effective solution for energy storage and conversion applications.

Formulating compatible non-flammable electrolyte for lithium-ion batteries with ethoxy (pentafluoro) cyclotriphosphazene.

Lithium (Li) ion batteries have played a great role in modern society as being extensively used in commercial electronic products, electric vehicles, and energy storage systems. However, battery safety issues have gained growing concerns as there might be thermal runaway, fire or even explosion under external abuse. To tackle these safety issues, developing non-flammable electrolytes is a promising strategy. However, the balance between the flame-retarding effect and the electrochemical performance of electrolytes remains a great challenge. Herein, we evaluate the function of ethoxy (pentafluoro) cyclotriphosphazene (PFPN) as an effective flame-retarding additive for lithium-ion batteries. The flammability of electrolytes is greatly suppressed with the introduction of a small amount of PFPN. Moreover, PFPN exhibited excellent compatibility with LiFePO4 (LFP) cathode and graphite (Gr) anode, the electrochemical performances of LFP|Li and Gr|Li half cells are virtually unaffected. Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) reveal the stable interphase between PFPN-containing electrolyte and LFP and Gr electrodes. Fourier transform infrared spectroscopy (FT-IR), Raman and nuclear magnetic resonance (NMR) spectra demonstrate the introduction of PFPN only exhibits negligible influence on the solvation structure of electrolyte. Benefiting from these merits of PFPN, the LFP|Gr cell shows desirable long-term cycling performance, which demonstrates great potential for practical application.

Highly-robust nanoplate-shaped V2O5 as an efficient cathode material for aqueous zinc ion batteries

The reaction mechanism along with long-term cycling performance of a nanoplate-shaped V2O5 cathode.

Dual-functional mediators of high-entropy Prussian blue analogues for lithiophilicity and sulfiphilicity in Li-S batteries.

Lithium-sulfur (Li-S) batteries are considered promising next-generation energy storage systems due to their high energy density (2600 W h kg-1) and cost-effectiveness. However, the shuttle effect of lithium polysulfides in sulfur cathodes and uncontrollable Li dendrite growth in Li metal anodes significantly impede the practical application of Li-S batteries. In this study, we address these challenges by employing a high-entropy Prussian blue analogue Mn0.4Co0.4Ni0.4Cu0.4Zn0.4[Fe(CN)6]2 (HE-PBA) composite containing multiple metal ions as a dual-functional mediator for Li-S batteries. Specifically, the HE-PBA composite provides abundant metal active sites that efficiently chemisorb lithium polysulfides (LiPSs) to facilitate fast redox conversion kinetics of LiPSs. In Li metal anodes, the exceptional lithiophilicity of the HE-PBA ensures a homogeneous Li ion flux, resulting in uniform Li deposition while mitigating the growth of Li dendrites. As a result, our work demonstrates outstanding long-term cycling performance with a decay rate of only 0.05% per cycle over 1000 cycles at 2.0 C. The HE-PBA@Cu/Li anode maintains a stable overpotential even after 600 h at 0.5 mA cm-2 under the total areal capacity of 1.0 mA h cm-2. This study showcases the application potential of the HE-PBA in Li-S batteries and encourages further exploration of prospective high-entropy materials used to engineer next-generation batteries.

Self-Standing Single-Ion Borate Salt-Based Polymer Electrolyte for Lithium Metal Batteries.

Polymer electrolytes (PEs) with excellent flexibility and superior compatibility toward lithium (Li) metal anodes have been deemed as one of the most promising alternatives to liquid electrolytes. However, conventional lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-based dual-ion PEs suffer from a low Li ion transference number and notorious Li dendrite growth. Here, a single-ion conducting polyborate salt without any fluorinated groups, polymeric lithium dihydroxyterephthalic acid borate (PLDPB), is presented for addressing the issues of Li metal batteries. Owing to a nearly immovable bulky anion and the presence of a rigid benzene structure, the PLDPB@poly(ethylene oxide) (PEO) PE exhibits an ultrahigh Li ion transference number (0.94) and excellent mechanical strength, which could significantly restrict the growth of Li dendrites. Postmortem analysis reveals that a fluorine-free solid electrolyte interphase (SEI) enriched with B-O and benzene-containing species is formed on the surface of the Li metal anode, thereby facilitating elimination of excessive parasitic reactions and simultaneously suppressing the formation of Li dendrites. Consequently, the LiFePO4/Li cells with PLDPB@PEO PEs show an improved long-term cycling performance and high capacity retention (90.0%) and Coulombic efficiency (99.9%) after 500 cycles. This work may inspire new ideas to boost the development of single-ion conducting salts for dendrite-free Li metal batteries.

Fabrication and oil-water separation properties of cerium oxide coated zirconium oxide composite membranes

Traditional oil-water separation membranes have high preparation costs and easy environmental pollution during the manufacturing process, so the development of new oil-water separation membranes with low cost and high environmental value is an important topic. In this work, cerium oxide coated zirconium oxide (CeO2/ZrO2) composite membranes are fabricated on cotton fabric by a combination of physical and chemical methods, where CeO2 is prepared using Gossypium sppas a template. The experimental results show that the surface of the composite membrane forms a rough structure with multiple pore channels and the CeO2/ZrO2 composite membrane shows super-hydrophobicity (152.2°) and superlipophilicity. At the same time, the CeO2/ZrO2 composite membrane shows very high separation efficiency (98.26 %−99.53 %) for four oil-water mixtures. After the long-term stability test and cycling performance test, the CeO2/ZrO2 composite membrane shows good separation performance, and the flux of the membrane reaches 34411.9 Lm−2h−1. Meanwhile, the contact angle of the composite membrane is tested for acidic and alkaline environments, and the result shows that it has certain corrosion resistance. This provides an extended strategy to reduce environmental pollution and improve separation efficiency.

Extreme Fast Charging of High Energy Density Lithium Ion Battery

The demand for high-energy-density batteries using Ni-rich cathodes is increasing due to the continuous expansion of the electric vehicle (EV) market. U.S. Department of Energy has stated the need for extreme-fast-charging (XFC) batteries that achieve an 80% state of charge (SOC) in less than 15 min. However, Ni-rich cathodes tend to lose capacity quickly under XFC conditions, which compromises their structural integrity. In addition, XFC conditions rapidly generate significant heat due to the high current applied to the cell, leading to the degradation of cell components. It is challenging to create Ni-rich cathodes that can withstand XFC conditions while still maintaining maximum energy density and long-term cycling performance. In this study, a cathode called Li[Ni0.92Co0.06Al0.01Nb0.01]O2 (Nb-NCA93) is introduced, which has a high energy density of 869 Wh kg-1. The presence of Nb in the cathode induces grain refinement in its secondary particles, reducing internal stress and preventing heterogeneity of Li concentration during cycling. When used in a full-cell, the Nb-NCA93 cathode reaches full charge within 12 minutes and retains 85.3% of its initial capacity after 1000 cycles, cycled at full depth of discharge. Furthermore, the refined microstructure of the Nb-NCA93 cathode limits heat generation under XFC conditions. References H.-H. Ryu, K.-J. Park, C. S. Yoon, Y.-K. Sun, Chem. Mater. 2018, 30, 1155 C. S. Yoon, H.-H. Ryu, G.-T. Park, J.-H Kim, K.-H. Kim, Y.-K Sun, J. Mater. Chem. A 2018, 6, 4126 U.-H. Kim, H.-H. Ryu, J.-H. Kim, R. Mücke, P. Kaghazchi, C. S. Yoon, Y.-K. Sun, Adv. Energy Mater. 2019, 9, 1803902

Synergistic Impact of Electrolyte Components: Interplay between the Novel Phosphorus-Based Additives and Conducting Salt Advancing NMC811||SiC Cell Performance

A lithium-ion battery (LIB) typically consists of an anode, a lithiated transition metal oxide cathode, and an electrolyte formulation containing inorganic lithium conducting salt in aprotic organic solvents/co-solvents, and functional additives. In-depth research is being conducted in order to develop novel chemistries for the next-generation LIBs. Within the line, silicon-based anodes and nickel-rich cathodes are recognized as two feasible next-generation electrode materials. The long-term galvanostatic cycling performance of resulting cell chemistries relies on the effectivity and robustness of solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) formed during the initial cycles and originate from the galvanostatic cycling conditions, as well as the complex interplay between electrolyte and corresponding electrodes .[1] To enhance the SEI and CEI properties, implementing functional electrolyte additives into baseline electrolyte has been shown to be one of the most effective and cost-favorable strategies. Film-forming additives sacrificially reduce and/or oxidize at corresponding electrodes to form protective layers (SEI and CEI).Previous research has shown that phosphorus-based additives improve electrode |electrolyte interfaces stability and simultaneously enhance cell flame-retardant capability advancing the overall cell performance.[2,3] In this report, we indicated part of the above-mentioned properties originate from the synergy between lithium hexafluorophosphate (LiPF6) which is the state-of-the-art (SOTA) electrolyte conducting salt in LIBs and considered functional additives. Here, we demonstrated the functionality of 2-phenoxy-1,3,2-dioxaphospholane (PhEPi) as a novel film-forming additive[4] and 2,2,4,4,6-pentafluoro-6-(2,2,2-trifluoroethoxy)-1,3,5,2λ5,4λ5,6λ5-triazatriphosphinine (CF3PFFPN) as a new flame-retardant additive, synthesized for the first time by our group. The presence of PhEPi and CF3PFPN at the optimum concentrations in the baseline electrolyte (1 M LiPF6 in EC: EMC 3:7 + 8 % VC) enhances the performance and safety of the resulting NMC811||Si-graphite (20% Si) cell chemistry. Impact of phospholane-based additive was confirmed by substituting LiPF6 with LiBF4 conducting salt and complementary post mortem analysis. This study along with improved cell chemistry, provided a better understanding and deeper insights into the synergistic interplay and impact of considered electrolyte components on the resulting NMC811||Si-graphite cell chemistry. [1] C. Wölke, B. A. Sadeghi, G. G. Eshetu, E. Figgemeier, M. Winter, I. Cekic-Laskovic, Advanced Materials Interfaces 2022, 9, DOI 10.1002/admi.202101898.[2] N. Von Aspern, D. Diddens, T. Kobayashi, M. Börner, O. Stubbmann-Kazakova, V. Kozel, G. V. Röschenthaler, J. Smiatek, M. Winter, I. Cekic-Laskovic, ACS Applied Materials and Interfaces 2019, 11, 16605–16618, DOI 10.1021/acsami.9b03359.[3] N. von Aspern, C. Wölke, M. Börner, M. Winter, I. Cekic-Laskovic, Journal of Solid State Electrochemistry 2020, 24, 3145–3156, DOI 10.1007/s10008-020-04781-1.[4] B. A. Sadeghi, C. Wölke, F. Pfeiffer, M. Baghernejad, M. Winter, I. Cekic-Laskovic, Journal of Power Sources 2023, 557, 232570, DOI 10.1016/j.jpowsour.2022.232570.

Towards Moisture Tolerant Lithium-Ion Batteries: A Systematic Investigation on the Effect of Moisture on Ni-Rich NMC Cathodes

In the ever-expanding lithium-ion battery (LIB) industry, lithium hexafluorophosphate (LiPF6) has been the most dominant lithium salt for preparing electrolytes. However, the challenges related to its moisture sensitivity (manifested by the formation of hydrofluoric acid) and thermal instability are yet to be addressed. Due to its improved ionic conductivity, reduced risk of producing hydrofluoric acid and better thermal and chemical stability, Lithium bis(fluorosulfonyl)imide (LiFSI) has been considered as a potential alternative salt to replace LiPF6. Nonetheless, LiFSI salt is currently not available in volumes relevant to industrial production; hindered by its high cost and the presence of trace quantities of chloride impurities. In addition, for operating cells at upper cut off voltages higher than 4.1~4.2 V, oxidative aluminum current collector corrosion [1] is a challenge.Among the high energy density LIB cathode materials, Nickel-rich LiNixMnyCozO2 (NMCs) are the most promising choices to fulfil the long mileage per charge requirements for powering electric vehicles [2]. In this study, the effect of moisture on the electrochemical performance of NMC622/Li and NMC622/graphite pouch cells was systematically investigated by adding water into 1 M LiFSI electrolyte. To better understand the interaction and effect of the added H2O with other electrolyte additives such as fluoroethylene carbonate (FEC), the electrochemical performance of the NMC622/Li half cells were tested with four different electrolytes; 1 M LiFSI in EC/DMC (50/50, v/v, control), 1 M LiFSI + 1000 ppm water, 1 M LiFSI + 10 wt% FEC, and 1 M LiFSI + 1000 ppm water + 10 wt% FEC. Double layered ultra-high molecular weight polyethylene separator (Solupor 3P07B) was used in all measurements. The water content in the electrolytes with 1000 ppm water was regularly monitored using the Karl-Fisher titration technique.It is intriguing that the addition of 1000 ppm water into the 1 M LiFSI electrolyte improved the specific discharge capacity and capacity retention of the NMC622/Li pouch cells. Furthermore, to investigate the morphological, microstructural, and chemical evolutions of the electrodes after short- and long-term cycling performance tests, postmortem characterizations such as ex situ XRD, S(T)EM, SEM/EDS, FTIR and XPS are being conducted.As expected, the oxidative aluminum current collector corrosion was scrutinized by running cyclic voltammetric measurements with the different electrolytes and the results were compared with that in 1 M LiPF6 (Figure 1a). It should be noted, however, that the voltammograms are obtained in the voltage range of 3.0 – 4.9 V. Ex situ SEM images of the cycled aluminum electrodes exhibited the formation of a thin film on the surface (Figure 1b, 1c), and the film formed on the aluminum electrode cycled with 10 wt% FEC was thicker compared to those with 1 M LiFSI and 1 M LiFSI + 1000 ppm H2O electrolytes. It was evident from the oxidative aluminum corrosion study that the current density and pitting corrosion were relatively smaller in the 10 wt% FEC containing electrolytes (Figure 1a). This is in agreement with the formation of relatively thicker films on the electrode surface with FEC containing electrolytes, as discussed above.Overall, it was evident from this study that addition of 1000 ppm water enhanced the discharge capacity and capacity retention of NMC622/Li pouch cells, and such moisture tolerant LiFSI based lithium-ion batteries can open new pathways which can ultimately enable the development of relatively higher dew point and less energy intensive dry rooms. However, for cell operations above ca. 4.3 V, proper prevention mechanisms are required for the oxidative aluminum current collector corrosion in such systems.

(Invited) Developing High-Energy All-Solid-State Batteries with Long Cycle Life

While conventional lithium-ion batteries (LIBs) continue to gain progress through incremental improvements, the presence of organic liquid electrolytes brings about fundamental safety issues as their reactivity and flammability subject LIBs to thermal runaway. [1-4] With higher energy densities and better safety performances, all-solid-state batteries (ASSBs) consisting of a 4 V-class cathode active material (CAM), an inorganic solid-state electrolyte (SE) and a lithium-metal anode are considered the future of energy storage technologies. [5-6] The development of practical ASSBs, however, has met a number of challenges. SEs simultaneously meeting the criteria in conductivity, stability and mechanical properties are yet to be discovered. At the anode, reductive degradation of SE, high interfacial impedance and dendrite formation are the most pressing issues. At the cathode, instabilities due to oxidative degradation of SE, reactivities between SE and CAM as well as the loss of mechanical integrity significantly limit ASSB performance.In this presentation, we discuss our recent effort in addressing these challenges, including the development of novel halide SEs, design of composite cathode structure that enables direct use of uncoated-LiNi0.8Co0.1Mn0.1O2 CAM, and implement of Li-metal based anodes that enable better interface with the SE. We demonstrate the excellent long-term cycling performance achieved on such cells and illustrate the underlying working mechanism. [7] The importance in proper matching of cathode, SE and anode properties as well as our views on future development of better-performing ASSB cells will be presented. References Arbizzani, G. Gabrielli and M. Mastragostino, Journal of Power Sources, 2011, 196, 4801-4805.Murmann, R. Schmitz, S. Nowak, N. Ignatiev, P. Sartori, I. Cekic-Laskovic and M. Winter, Journal of The Electrochemical Society, 2015, 162, A1738.Cao, X. Ren, L. Zou, M. H. Engelhard, W. Huang, H. Wang, B. E. Matthews, H. Lee, C. Niu and B. W. Arey, Nature Energy, 2019, 4, 796-805.Fan, L. Chen, O. Borodin, X. Ji, J. Chen, S. Hou, T. Deng, J. Zheng, C. Yang, S.-C. Liou, K. Amine, K. Xu and C. Wang, Nature Nanotechnology, 2018, 13, 715-722.Janek and W. G. J. N. E. Zeier, Nature Energy, 2016, 1, 1-4.Famprikis, P. Canepa, J. A. Dawson, M. S. Islam and C. Masquelier, Nature Materials, 2019, 18, 1278-1291.Y. Kim, H. Cha, R. Kostecki and G. Chen, ACS Energy Letters 2023, 8, 521.

In-Situ Convertible Amorphous Silicon Nitride (SiNx) Anode: Resolving the Long-Term Cyclic Instability of Silicon

Silicon (Si) has shown its promises as anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high theoretical capacity1. However, its practical application has been impeded by the severe cyclic instability caused by a large volume change during (de) lithiation. Recently, a new family of silicon-based anode materials called “in-situ convertible-type anode materials” has emerged to resolve the cyclic instability of silicon.2,3 This family includes sub-stoichiometric oxides, nitrides, and carbides of silicon (SiAx, where A = N, C, O). The working principle of these materials follow two mechanisms: (1) irreversible conversion and (2) reversible alloying/dealloying. During initial lithiation, the conversion reaction occurs, forming Si-Li nanodomains inside a stable Li-conductive matrix denoted as LiySixA (A=N, C, O). In the subsequent cycles, the Si-Li nanodomains reversibly alloying/dealloying with Li, while the Li-conductive matrix ensures stable cycling and good rate capability. Such composition mitigates the challenges associated with Si’s large volume change ensuring long-term cyclic stability.In this study, we demonstrate our approach on the development of silicon-rich, sub-stochiometric, amorphous silicon nitride (SiNx) nanoparticles, as an in-situ convertible-type anode material and its long-term cyclic performance for LIBs. In this approach, the SiNx nanoparticles are produced via the decomposition of silane gas in the presence of ammonia using an industrially scalable, free space reactor (FSR), which is developed and customized in our research institute (IFE) (Fig. 1a). Proper proportions of silane and ammonia gases are introduced into the reactor, leading to the nucleation and growth of SiNx nanoparticles. The synthesized SiNx nanoparticles exhibited Si-rich domain and amorphous structure with particle size between 100 nm - 200 nm (Fig. 1b), as confirmed by SEM, TEM and XRD characterizations. The presence of nitrogen in silicon dominated composition is revealed by energy dispersive electron spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR). The scalability and reproducibility of the FSR synthesis method makes it a promising approach for the industrial production of SiNx for advance anode materials for LIBs.The electrochemical performance of the synthesized SiNx anode is evaluated by galvanostatic cycling and electrochemical impedance spectroscopy. The electrochemical performance of the SiNx performed on the electrodes with the active mass loading of 0.987 mg/cm2 and cycled at C/5 rate has preserved its capacity about 852 mAh/g after around 600 cycles. As seen from Fig. 1c, the improved cyclic stability of the SiNx compared with pure silicon indicates that the Li-conductive matrix plays crucial role in stabilizing the anode. The authors emphasize the need for further investigation and collaboration, particularly in advance characterization, to better understand the composition and mechanisms of the Li-conductive matrix in the SiNx anode. Such detailed understanding can significantly benefit the conversion-type anode materials for their widespread use in future LIB technologies.References Zuo, X., Zhu, J., Müller-Buschbaum, P. & Cheng, Y.-J. Silicon based lithium-ion battery anodes: A chronicle perspective review. Nano Energy 31, 113–143 (2017).Ulvestad, A. et al. Stoichiometry-Controlled Reversible Lithiation Capacity in Nanostructured Silicon Nitrides Enabled by in Situ Conversion Reaction. ACS Nano 15, 16777–16787 (2021).Kilian, S. O. et al. Active Buffer Matrix in Nanoparticle-Based Silicon-Rich Silicon Nitride Anodes Enables High Stability and Fast Charging of Lithium-Ion Batteries. Advanced Materials Interfaces 9, 2201389 (2022). Figure 1

Pre-lithiated silicon/carbon nanosphere anode with enhanced cycling ability and coulombic efficiency for lithium-ion batteries

The high capacity and low charge potential of Si-based materials have attracted significant attention in recent years, positioning them as promising candidates for lithium-ion batteries (LIBs). However, these materials face challenges such as insufficient conductivity and substantial volumetric expansion. To address these concerns, two strategies have been employed: constructing a carbon coating layer and implementing pre-lithiation. Si nanospheres are dispersed in a precursor solution and subsequently annealed to undergo carbonization, resulting in the formation of Si/C composites. The Si/C anode has been pre-lithiated using a simple electrochemical pre-lithiation method to enhance the initial coulombic efficiency. Specifically, it achieved a reversible capacity of 1018.4 mAh g−1 after 500 cycles at a current density of 0.5 A g−1 for LIBs. Even at a high current density of 5 A g−1, the capacity remained stable at 266.4 mAh g−1 after 500 cycles. Moreover, pre-lithiation significantly improved the coulombic efficiency in the first cycle, increasing it from 64.89 % to 96.18 %. The enhanced performance can be attributed to the carbon coating layer, which improves material conductivity and mitigates volume expansion. Our work demonstrates that the prepared Si/C anode exhibits excellent long-term cycling performance and a high-rate capability. These findings provide valuable insights for developing high-performance LIBs by leveraging the specific structure of Si-based materials.

Unveiling high-power and high-safety lithium-ion battery separator based on interlayer of ZIF-67/cellulose nanofiber with electrospun poly(vinyl alcohol)/melamine nonwoven membranes

Due to the poor thermal stability of conventional separators, lithium-ion batteries require a suitable separator to maintain system safety for long-term cycling performance. It must have high porosity, superior electrolyte uptake ability, and good ion-conducting properties even at high temperatures. In this work, we demonstrate a novel composite membrane based on sandwiching of zeolitic imidazole frameworks-67 decorated cellulose acetate nanofibers (ZIF-67@CA) with electrospun poly(vinyl alcohol)/melamine (denoted as PVAM) nonwoven membranes. The as-prepared sandwich-type membranes are called PVAM/x%ZIF-67@CA/PVAM. The middle layer of composite membranes is primarily filled with different weight percentages of ZIF-67 nanoparticles (x = 5, 15, and 25 wt%), which both reduces the non-uniform porous structure of CA and increases its thermal stability. Therefore, our sandwich-type PVAM/x%ZIF-67@CA/PVAM membrane exhibits a higher thermal shrinkage effect at 200 °C than the commercial polyethylene (PE) separator. Due to its high electrolyte uptake (646.8%) and porosity (85.2%), PVAM/15%ZIF-67@CA/PVAM membrane achieved high ionic conductivity of 1.46 × 10-3 S cm−1 at 70 °C, as compared to the commercial PE separator (ca. 6.01 × 10-4 S cm−1 at 70 °C). Besides, the cell with PVAM/15%ZIF-67@CA/PVAM membrane shows an excellent discharge capacity of about 167.5 mAh g−1after 100 cycles at a 1C rate with a capacity retention of 90.3%. The ZIF-67 fillers in our sandwich-type composite membrane strongly attract anions (PF6-) through Lewis' acid-base interaction, allowing uniform Li+ ion transport and suppressing Li dendrites. As a result, we found that the PVAM/15%ZIF-67@CA/PVAM composite nonwoven membrane is applicable to high-power, high-safety lithium-ion battery systems that can be used in electric vehicles (EVs).

Acid-base encapsulation prepared N/P co-doped carbon-coated natural graphite for high-performance lithium-ion batteries

The incorporation of natural graphite as an anode material effectively enhances the lithium storage capacity of lithium-ion batteries. However, the lower specific capacity of graphite anodes and the slow dynamics limit the application of fast charging in daily life. In this work, we proposed an acid-base neutralization strategy to prepare N/P co-doped carbon coated natural graphite for high-performance lithium-ion batteries. Electrochemical testing shows that the prepared NG-PN@C electrode has a first discharge specific capacity of 429.61mAh/g and a high initial Coulombic efficiency (ICE) of 87.39 %, exhibiting a capacity three times higher than that of the commercial natural graphite at a rate of 3C. The enhanced performance can be attributed to the synergistic interplay between N/P co-doping and carbon coating. This interplay heightens the chemical reactivity of the graphite surface, an appropriate introduction of heteroatom into graphite (carbon) hosts is beneficial for Li heterogeneous nucleation and thus renders a uniform Li deposition. In addition, the stable carbon layer of about 3 nm can mitigate the volume expansion throughout cycling and improve rate capability and long-term cycling performance. This simple and low-cost acid-base neutralization strategy not only provides an eco-friendly method for the modification of graphite anodes, achieving doping of N/ P and coating a carbon layer on graphite but also offers inspiration for the advancement of alternative nanocomposites dedicated to improving their electrochemical properties.

Quantitative regulation of electrochemical-mechanical performance of composite cathode in all-solid-state batteries

The intricate interplay between electrochemical and mechanical phenomena and the volumetric changes leading to interfacial stability within composite cathodes exerts a profound influence on the long-term cycling performance of all-solid-state batteries (ASSBs). This study quantitatively assesses a novel approach aimed at modulating the electrochemical-mechanical performance within composite cathodes by integrating LiNi1−x-yCoxMnyO2 (NCM) with LiCoO2 (LCO) particles. The insightful evaluation is conducted through a multiphysics modeling strategy. The NCM and LCO particles, each displaying distinct open-circuit voltage-concentration relationships, interact and evolve in a two-stage manner during charging, with their coupled electrochemical-mechanical behaviors remaining relatively insensitive to particle positioning. Stage I is dominated by the mechanical response due to NCM particle shrinkage (stress σMises≈1.3 GPa, debonding gap Gd≈1.8 nm). Stage II is governed by the mechanical stress accumulation resulting from the expansion of LCO particles (σMises≈7 GPa, Gd≈62 nm). The choice of solid electrolyte (SE) materials plays a competing role with the modulating of NCM/LCO ratio since SEs possess high compression-bearing capabilities favoring a higher LCO content, while those characterized by robust interfacial strength with particles allow for greater NCM content. Results offer valuable insights into designing more resilient and enduring composite cathodes, unlocking the design and manufacturing of long-cycling ASSBs.

Fe-Nx sites coupled with core-shell FeS@C nanoparticles to boost the oxygen catalysis for rechargeable Zn-air batteries

The development of efficient single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) remains a formidable challenge, primarily due to the symmetric charge distribution of metal single-atom sites (M-N4). To address such issue, herein, Fe-Nx sites coupled synergistic catalysts fabrication strategy is presented to break the uniform electronic distribution, thus enhancing the intrinsic catalytic activity. Precisely, atomically dispersed Fe-Nx sites supported on N/S-doped mesoporous carbon (NSC) coupled with FeS@C core-shell nanoparticles (FAS-NSC@950) is synthesized by a facile hydrothermal reaction and subsequent pyrolysis. Due to the presence of an in situ-grown conductive graphitic layer (shell), the FeS nanoparticles (core) effectively adjust the electronic structure of single-atom Fe sites and facilitate the ORR kinetics via short/long-range coupling interactions. Consequently, FAS-NSC@950 displays a more positive half-wave potential (E1/2) of 0.871 V with a significantly boosted ORR kinetics (Tafel slope = 52.2 mV dec−1), outpacing the commercial Pt/C (E1/2 = 0.84 V and Tafel slope = 54.6 mV dec−1). As a bifunctional electrocatalyst, it displays a smaller bifunctional activity parameter (ΔE) of 0.673 V, surpassing the Pt/C-RuO2 combination (ΔE = 0.724 V). Besides, the FAS-NSC@950-based zinc-air battery (ZAB) displays superior power density, specific capacity, and long-term cycling performance to the Pt/C-Ir/C-based ZAB. This work significantly contributes to the field by offering a promising strategy to enhance the catalytic activity of SACs for ORR, with potential implications for energy conversion and storage technologies.