Improved Cycle Life Research Articles

Tailoring the Size of Reduced Graphene Oxide Sheets to Fabricate Silicon Composite Anodes for Lithium-Ion Batteries.

The integration of a silicon (Si) anode into lithium-ion batteries (LIBs) holds great promise for energy storage, but challenges arise from unstable electrochemical reactions and volume changes during cycling. This study investigates the influence of reduced graphene oxide (rGO) size on the performance of rGO-protected Si composite (Si@rGO) anodes. Two sizes of graphene oxide (GO(L) and GO(S)) are used to synthesize Si@rGO composites with a core-shell structure by spray drying and thermal reduction. Electrochemical evaluations show the advantages of the Si@rGO(S) anode with improved cycle life and cycling efficiency over Si@rGO(L) and pure Si. The Si@rGO(S) anode facilitates the formation of a stable LiF-rich solid electrolyte interface (SEI) after cycling, ensuring enhanced capacity retention and swelling control. Rate capability tests also demonstrate the superior high-power performance of Si@rGO(S) with low and stable resistances in Si@rGO(S) over extended cycles. This study provides critical insights into the tailoring of graphene-protected Si composites, highlighting the critical role of rGO size in shaping structural and electrochemical properties. The Si material wrapped by graphene with an optimal lateral size of graphene emerges as a promising candidate for high-performance LIB anodes, thereby advancing electrochemical energy storage technologies.

Chemical short-range disorder in lithium oxide cathodes.

Ordered layered structures serve as essential components in lithium (Li)-ion cathodes1-3. However, on charging, the inherently delicate Li-deficient frameworks become vulnerable to lattice strain and structural and/or chemo-mechanical degradation, resulting in rapid capacity deterioration and thus short battery life2,4. Here we report an approach that addresses these issues using the integration of chemical short-range disorder (CSRD) into oxide cathodes, which involves the localized distribution of elements in a crystalline lattice over spatial dimensions, spanning a few nearest-neighbour spacings. This is guided by fundamental principles of structural chemistry and achieved through an improved ceramic synthesis process. To demonstrate its viability, we showcase how the introduction of CSRD substantially affects the crystal structure of layered Li cobalt oxide cathodes. This is manifested in the transition metal environment and its interactions with oxygen, effectively preventing detrimental sliding of crystal slabs and structural deterioration during Li removal. Meanwhile, it affects the electronic structure, leading to improved electronic conductivity. These attributes are highly beneficial for Li-ion storage capabilities, markedly improving cycle life and rate capability. Moreover, we find that CSRD can be introduced in additional layered oxide materials through improved chemical co-doping, further illustrating its potential to enhance structural and electrochemical stability. These findings open up new avenues for the design of oxide cathodes, offering insights into the effects of CSRD on the crystal and electronic structure of advanced functional materials.

Sustainable Prelithiation Strategy: Enhancing Energy Density and Lifespan with Ultrathin Li‐Mg‐Al Alloy Foil

AbstractPrelithiation is a well‐established strategy for enhancing battery energy density. However, traditional prelithiation approaches have primarily addressed compensating for the initial active lithium loss (ALL) while overlooking the ALL during extended cycling. In response, a novel method is introduced by increasing the prelithiation degree and pre‐storing stable LiCx within the anode. This innovation facilitates sustainable lithium replenishment, resulting in a significant improvement in battery cycle life and energy density. Moreover, challenges associated with using pure Li foils to realize this strategy in contact prelithiation are revealed, such as difficulties in thinning to less than 5 µm, and the loss of the electronic pathway during prelithiation, resulting in low lithium utilization rates and numerous residues. Additionally, the significantly accelerated capacity fading caused by these residues, typically emerging after hundreds of cycles, has been overlooked. To overcome these challenges, an ultrathin Li‐Mg‐Al alloy foil is developed with significantly improved mechanical properties and delithiation behavior. During prelithiation, the 96Li2Mg2Al alloy maintains a complete film structure with numerous micropores, avoiding randomly distributed debris. This structure ensures high utilization, unimpeded electronic pathways, and efficient electrolyte filtration. By employing a 5‐µm 96Li2Mg2Al foil for sustainable prelithiation, a substantial improvement in energy density is achieved and tripled the battery's lifespan.

Recent Advances in Catalyst Design and Performance Optimization of Nanostructured Cathode Materials in Zinc-Air Batteries.

This review focuses on the advanced design and optimization of nanostructured zinc-air batteries (ZABs), with the aim of boosting their energy storage and conversion capabilities. The findings show that ZABs favor porous nanostructures owing to their large surface area, and this enhances the battery capacity, catalytic activity, and life cycle. In addition, the nanomaterials improve the electrical conductivity, ion transport, and overall battery stability, which crucially reduces dendrite growth on the zinc anodes and improves cycle life and energy efficiency. To obtain a superior performance, the importance of controlling the operational conditions and using custom nanostructural designs, optimal electrode materials, and carefully adjusted electrolytes is highlighted. In conclusion, porous nanostructures and nanoscale materials significantly boost the energy density, longevity, and efficiency of Zn-air batteries. It is suggested that future research should focus on the fundamental design principles of these materials to further enhance the battery performance and drive sustainable energy solutions.

Catalytic role of in-situ formed C-N species for enhanced Li2CO3 decomposition

Sluggish kinetics of the CO2 reduction/evolution reactions lead to the accumulation of Li2CO3 residuals and thus possible catalyst deactivation, which hinders the long-term cycling stability of Li-CO2 batteries. Apart from catalyst design, constructing a fluorinated solid-electrolyte interphase is a conventional strategy to minimize parasitic reactions and prolong cycle life. However, the catalytic effects of solid-electrolyte interphase components have been overlooked and remain unclear. Herein, we systematically regulate the compositions of solid-electrolyte interphase via tuning electrolyte solvation structures, anion coordination, and binding free energy between Li ion and anion. The cells exhibit distinct improvement in cycling performance with increasing content of C-N species in solid-electrolyte interphase layers. The enhancement originates from a catalytic effect towards accelerating the Li2CO3 formation/decomposition kinetics. Theoretical analysis reveals that C-N species provide strong adsorption sites and promote charge transfer from interface to *CO22− during discharge, and from Li2CO3 to C-N species during charge, thereby building a bidirectional fast-reacting bridge for CO2 reduction/evolution reactions. This finding enables us to design a C-N rich solid-electrolyte interphase via dual-salt electrolytes, improving cycle life of Li-CO2 batteries to twice that using traditional electrolytes. Our work provides an insight into interfacial design by tuning of catalytic properties towards CO2 reduction/evolution reactions.

Impact of LiAl Nucleation Kinetics on the Microstructural Evolution of Aluminum Foil Anodes in Lithium-ion Batteries

Aluminum foil anodes have the potential to significantly improve the energy density, safety, cost, and sustainability of Li-ion batteries (LIB). However, their adoption is limited by their notoriously poor cycle life, and the dramatic structural transformations of Al foil anodes during formation and cycling remain poorly understood. In this work, we investigate how the nucleation and growth kinetics of LiAl control the microstructural evolution and cycle life of Al foil anodes. First, we demonstrate the unique sensitivity of Al foil anodes to the cell design and cycling conditions and emphasize the necessity of electrochemical testing in practical full cells. Operando electrochemical impedance spectroscopy (EIS) is combined with scanning electron microscope (SEM) imaging of the lithiated foils to elucidate the relationships between LiAl nucleation kinetics and the resulting LiAl microstructure. Particularly, we investigate the effects of annealing the pristine foils, and controlling the overpotential and temperature during formation, showing that as-rolled foils lithiated at high overpotentials give a columnar LiAl microstructure. Finally, we show that uncontrolled LiAl nucleation during cycling quickly destroys this favorable columnar structure, and a significant improvement in cycle life of LiFePO4 || Al full cells is achieved by limiting the depth-of-discharge to <75%.

A Comprehensive Experimental Study on Microstructure‐Graded Graphite Anodes for Enhancing Fast‐Charging Capability of Lithium‐Ion Batteries

Lithium‐ion batteries with high gravimetric capacity density and improved cycle life performance under fast‐charging conditions are crucial for widespread electric vehicle (EV) adoption. This study investigates how designing graphite anode microstructure, specifically porosity, and particle‐size gradients, improves lithium‐ion (Li+) transport during fast‐charging conditions. Three‐layered graphite anodes with varying porosity (24%, 36%, 46%) and particle size gradients (3, 5, 10 μm) were compared to a conventional single‐layered electrode in half‐cell configurations. At room temperature and high discharge rate (2C), both gradient structures showed significantly enhanced capacity retention (80% and 67% vs. 50%) compared to the conventional electrode, highlighting the effectiveness of microstructure engineering for fast charging. The study also investigated the temperature's impact on cycle life. After 200 cycles at 2°C and 45°C, all gradient structures demonstrated superior capacity retention (≈80%) compared to the conventional electrode (35%), suggesting the gradients mitigate degradation rate at high temperatures. Electrochemical impedance spectroscopy confirmed superior Li+ diffusion and lower resistivity in gradient electrodes. Simulations explored the influence of gradient profiles on reaction kinetics across the electrode thickness. Overall, this research demonstrates that the fast‐charging capability of graphite electrodes can be greatly enhanced by engineering the electrode microstructure, thereby making EV technology more accessible and appealing.

Tunable LiZn‐Intermetallic Coating Thickness on Lithium Metal and Its Effect on Morphology and Performance in Lithium Metal Batteries

AbstractLithium metal batteries are promising next‐generation rechargeable batteries with high energy density. However, the high reactivity of lithium metal leads to an undesirable growth of high surface area lithium during electrodeposition and ‐dissolution and remains a key challenge that must be addressed to enable commercialization. Modification of the Li metal surface to obtain protective coatings is a common method to overcome these challenges. In this study, the influence of the thickness of an intermetallic coating on Li metal is investigated after application by means of thermal evaporation. In addition, the relevance of pre‐treatments in reducing the native layer thickness and surface roughness by roll‐pressing Li metal prior to coating is demonstrated. Morphological analyses are performed on cross‐sections prepared under cryogenic conditions to investigate the origin of high surface area lithium growth and coating cracks after electrodeposition and ‐dissolution processes. The results obtained support the conclusion that the exclusive combination of roll‐pressed Li metal foil followed by coating reduces overvoltage and improves cycle life at elevated current densities.

High-Entropy Materials for Lithium Batteries

High-entropy materials (HEMs) constitute a revolutionary class of materials that have garnered significant attention in the field of materials science, exhibiting extraordinary properties in the realm of energy storage. These equimolar multielemental compounds have demonstrated increased charge capacities, enhanced ionic conductivities, and a prolonged cycle life, attributed to their structural stability. In the anode, transitioning from the traditional graphite (372 mAh g−1) to an HEM anode can increase capacity and enhance cycling stability. For cathodes, lithium iron phosphate (LFP) and nickel manganese cobalt (NMC) can be replaced with new cathodes made from HEMs, leading to greater energy storage. HEMs play a significant role in electrolytes, where they can be utilized as solid electrolytes, such as in ceramics and polymers, or as new high-entropy liquid electrolytes, resulting in longer cycling life, higher ionic conductivities, and stability over wide temperature ranges. The incorporation of HEMs in metal–air batteries offers methods to mitigate the formation of unwanted byproducts, such as Zn(OH)4 and Li2CO3, when used with atmospheric air, resulting in improved cycling life and electrochemical stability. This review examines the basic characteristics of HEMs, with a focus on the various applications of HEMs for use as different components in lithium-ion batteries. The electrochemical performance of these materials is examined, highlighting improvements such as specific capacity, stability, and a longer cycle life. The utilization of HEMs in new anodes, cathodes, separators, and electrolytes offers a promising path towards future energy storage solutions with higher energy densities, improved safety, and a longer cycling life.

Increasing the Cycle Life of Zinc Metal Anodes and Nickel-Zinc Cells Using Flow-Through Alkaline Electrolytes

Alkaline electrolyte flow through porous Zn anodes and Ni(OH)2 cathodes can overcome diffusion limits, reduce dendrite growth, and improve cycle life. Zinc deposition morphology improves with low flow rates electrolyte in KOH/ZnO electrolytes at current densities near the diffusion-limit regime. Zinc dendrites present without flow are suppressed by micrometer-per-second flow at concentrations ranging from 0.2 to 0.6 M ZnO dissolved in 6 M and 10 M KOH solutions. Zn-Cu asymmetric cell tests reveal that flowing electrolyte increases the lifespan by more than 6 times in the diffusion-limit regime by suppressing gas evolution and dendrite formation. Ni-Zn cell tests show that a flow-assisted battery cycles 1500 times with over 95% Coulombic efficiency (CE) at 35 mA cm−2 current density and 7 mAh/cm2 charge capacity, increasing the battery lifespan by 17 times compared with a stagnant Ni-Zn cell. Flow-through electrolyte also stabilizes the Zn electrode in the over-limiting regime, achieving approximately 4 times increased lifespan and 297 cycles with over 90% CE at 52 mA cm−2.

Stoichiometric Ti3C2Tx Coating for Inhibiting Dendrite Growth in Anode‐Free Lithium Metal Batteries

Lithium metal batteries (LMBs) and anode‐free LMBs (AFLMBs) present a solution to the need for batteries with a significantly superior theoretical energy density. However, their adoption is hindered by low Coulombic efficiency (CE) and rapid capacity fading, primarily due to the formation of unstable solid electrolyte interphase (SEI) layer and Li dendrite growth as a result of uneven Li plating. Here, we report on the use of a stoichiometric Ti3C2Tx (S‐Ti3C2Tx) MXene coating on the copper current collector to enhance the cyclic stability of an anode‐free lithium metal battery. The S‐Ti3C2Tx coating provides abundant nucleation sites, thereby lowering the overpotential for Li nucleation, and promoting uniform Li plating. Additionally, the fluorine (−F) termination of S‐Ti3C2Tx participates in the SEI formation, producing a LiF‐rich SEI layer, vital for stabilizing the SEI and improving cycle life. Batteries equipped with S‐Ti3C2Tx@Cu current collectors displayed reduced Li consumption during stable SEI formation, resulting in a significant decrease in capacity loss. AFLMBs with S‐Ti3C2Tx@Cu current collectors achieved a high initial capacity density of 4.2 mAh cm−2, 70.9% capacity retention after 50 cycles, and an average CE of 98.19% in 100 cycles. This innovative application of MXenes in the energy field offers a promising strategy to enhance the performance of AFLMBs and could potentially accelerate their commercial adoption.

Artificial Hydrophilic Organic and Dendrite-Suppressed Inorganic Hybrid Solid Electrolyte Interface Layer for Highly Stable Zinc Anodes.

Aqueous zinc-ion batteries (AZIBs) have gained significant attentions for their inherent safety and cost-effectiveness. However, challenges, such as dendrite growth and anodic corrosion at the Zn anode, hinder their commercial viability. In this paper, an organic-inorganic coating layer (Nafion-TiO2) was introduced to protect the Zn anode and electrolyte interface. Briefly, Nafion effectively shields against the corrosion from water molecules through the hydrophobic wall of -CF3 and guided zinc deposition from the -SO3 functional group, while TiO2 particles with a higher Young's modulus (151 GPa vs 120 GPa from Zn metal) suppress the zinc dendrite formation. As a result, with the protection of Nafion-TiO2, the symmetrical Zn∥Zn battery shows an improved cycle life of 1,750 h at 0.5 mA cm-2, and the full cell based on Zn∥MnO2 shows a long cycle life over 1,500 cycles at 1 A g-1. Our research offers a novel approach for protecting zinc metal anodes, potentially applicable to other metal anodes such as those in lithium and sodium batteries.

Constructing Matching Cathode-Anode Interphases with Improved Chemo-mechanical Stability for High-Energy Batteries.

Coupling Ni-rich layered oxide cathodes with Si-based anodes is one of the most promising strategies to realize high-energy-density Li-ion batteries. However, unstable interfaces on both cathode and anode sides cause continuous parasitic reactions, resulting in structural degradation and capacity fading of full cells. Herein, lithium tetrafluoro(oxalato) phosphate is synthesized and applied as a multifunctional electrolyte additive to mitigate irreversible volume swing of the SiOx anode and suppress undesirable interfacial evolution of the LiNi0.83Co0.12Mn0.05O2 (NCM) cathode simultaneously, resulting in improved cycle life. Benefiting from its desirable redox thermodynamics and kinetics, the molecularly tailored additive facilitates matching interphases consisting of LiF, Li3PO4, and P-containing macromolecular polymer on both the NCM cathode and SiOx anode, respectively, modulating interfacial chemo-mechanical stability as well as charge transfer kinetics. More encouragingly, the proposed strategy enables 4.4 V 21700 cylindrical batteries (5 Ah) with excellent cycling stability (92.9% capacity retention after 300 cycles) under practical conditions. The key finding points out a fresh perspective on interfacial optimization for high-energy-density battery systems.

How Solvation Energetics Dampen the Hydrogen Evolution Reaction to Maximize Zinc Anode Stability

AbstractAqueous zinc metal batteries (AZMB) are emerging as a promising alternative to the prevailing existing Lithium‐ion battery technology. However, the development of AZMBs is hindered due to challenges including dendrite formation, hydrogen evolution reaction (HER), and ZnO passivation on the anode. Here, a tetraalkylsulfonamide (TAS) additive for suppressing HER, dendrite formation, and enhancing cyclability is rationally designed. Only 1 mm TAS is found that can effectively displace water molecules from the Zn2+ solvation shell, thereby altering the solvation matrix of Zn2+ and disrupting the hydrogen bond network of free water, as demonstrated through 67 Zn and 1H nuclear magnetic resonance spectroscopy, high‐resolution mass spectrometry (HRMS), and density functional theory (DFT) studies. Voltammetry synchronized with in situ monitoring of the electrode surface reveals suppressed dendritic growth and HER in the presence of TAS. Electrochemical mass spectrometry (ECMS) captures real‐time HER suppression during Zn electrodeposition, revealing the ability of TAS to suppress the HER by an order of magnitude. A ≈25‐fold cycle life improvement from ≈100 h to over 2500 h in coin cells cycled in the presence of TAS. Furthermore, by suppressing passivation product formation, it is demonstrated that strategy robustly maximizes the stability of Zn metal anodes.

Hybrid battery energy storage for light electric vehicle — From lab to real life operation tests

The aim of the research presented in the paper is to improve the lifetime of lead-acid battery systems which are widely used in low-speed electric vehicles or utility vehicles, since the cycle life of lead-acid batteries is nonlinearly dependent on the depth of discharge and electrolyte temperature. The solution proposed here is to connect lead-acid batteries with a small lithium‑iron-phosphate battery using only a diode. This connection is simple and does not require the use of an actively controlled converter. The concept was tested at various levels of an experiment, from the initial calculation of cycle life improvement and simulation, through a laboratory experiment, all the way to operational environment tests. The results obtained confirmed the main assumptions of the study: decrease in the depth of discharge of lead-acid battery for the distance traveled of around 17 %—which would translate into a 30 % better cycle life according to the characteristics indicated by the producers—and decrease in the root mean square and maximum current values of lead-acid battery by around 40–50 % and 26 %, respectively. Range extension was also achieved in vehicles. The solution has been successfully introduced to the market and is now used in few light electric vehicles.

Improvement of cycle life for layered oxide cathodes in sodium-ion batteries

In this review, research progress on layered oxide cathodes for SIBs in recent years is summarized, with emphasis on the problems of poor cycle life caused by irreversible phase transition, Jahn–Teller effect and interface deterioration, and several strategies are proposed to alleviate these issues.

Understanding How the Suppression of Insertion-Induced Phase Transitions Leads to Fast Charging in Nanoscale LixMoO2.

Fast-charging Li-ion batteries are technologically important for the electrification of transportation and the implementation of grid-scale storage, and additional fundamental understanding of high-rate insertion reactions is necessary to overcome current rate limitations. In particular, phase transformations during ion insertion have been hypothesized to slow charging. Nanoscale materials with modified transformation behavior often show much faster kinetics, but the mechanism for these changes and their specific contribution to fast-charging remain poorly understood. In this work, we combine operando synchrotron X-ray diffraction with electrochemical kinetics analyses to illustrate how nanoscale crystal size leads to suppression of first-order insertion-induced phase transitions and their negative kinetic effects in MoO2, a tunnel structure host material. In electrodes made with micrometer-scale particles, large first-order phase transitions during cycling lower capacity, slow charge storage, and decrease cycle life. In medium-sized nanoporous MoO2, the phase transitions remain first-order, but show a considerably smaller miscibility gap and shorter two-phase coexistence region. Finally, in small MoO2 nanocrystals, the structural evolution during lithiation becomes entirely single-phase/solid-solution. For all nanostructured materials, the changes to the phase transition dynamics lead to dramatic improvements in capacity, rate capability, and cycle life. This work highlights the continuous evolution from a kinetically hindered battery material in bulk form to a fast-charging, pseudocapacitive material through nanoscale size effects. As such, it provides key insight into how phase transitions can be effectively controlled using nanoscale size and emphasizes the importance of these structural dynamics to the fast rate capability observed in nanostructured electrode materials.

Improved Cycle Life and Determination of Li Ion Transport Parameters in Mixed Cation Doped Ni-Rich NMC

Ni-rich Li-ion cathode materials like NMC-9.5.5 (LiNi0.9Mn0.05Co0.05O2) are of interest due to their higher energy density and limited cobalt content, aiding the transition away from critical raw materials, when compared to materials like NMC111 - 622. This has the advantage of reducing production costs while maintaining a high working voltage and capacity. However, the high nickel content of these materials can be detrimental due to disorder brought by Li+/Ni2+ cation mixing, lithium residuals, and irreversible phase changes during operation resulting in significant capacity fade during cycling. Similarly, the different synthesis methods and treatments drastically affect the morphological, structural, and electrochemical propertiesWe present a structural and electrochemical study of NMC-9.5.5 prepared at scale via a hydroxide coprecipitation synthesis in a 5 L continuous stirred reactor tank (CSTR). In this work, bulk doping and co-doping with two metal cations are investigated with a simple and scalable method to achieve mixed metal and mixed valence doped NMC-9.5.5 with the aim to further improve cycle life and stability. Additionally, the effect of bulk doping on the thermodynamic and kinetic properties of the cathode material are investigated in both half-cells and full-cells using galvanostatic intermittent titration technique (GITT) and electrical impedance spectroscopy (EIS), where a 3-electrode configuration is used to elucidate the individual electrode potentials and stoichiometries.The bulk doping of the transition metal layer was found to significantly reduce the capacity fade in the NMC-9.5.5, increasing the capacity retention after 100 cycles from 78% in the undoped material to 92% and 89% in the doped and co-doped NMC-9.5.5 half-cells. The mixed metal co-doped material was also effective in delivering a higher specific capacity than the baseline throughout the full cycling range. The improved cycling performance can be understood by the inspection of the differential capacity plots, which show a suppression of the H2-H3 irreversible phase transition in the doped material and stabilisation of the peak to a higher voltage compared to the baseline. The effect of doping on the structural stabilisation is similarly reflected in the XRD characterisation, in which the introduction of the metal cation acts to constrain the detrimental Li+/Ni2+ cation mixing due to a widening of the transition metal channel. This is also supported by the EXAFS characterisation that indicate the dopants may act to stabilise the local Ni environment. These structural changes appear to be further beneficial in facilitating improved Li ion transport properties in the doped material as evidenced by the lower charge transfer resistances during cycling and increased diffusion coefficient.This research illustrates the high capacity performance of low cobalt cathode materials thus reducing the reliance on critical materials, as well as the ability to produce Ni-rich cathode material at large scale and further stabilise its cycle life by simple structural engineering. Improved materials manufacturing processes will enable a greater understanding of the synthesis process and enable more sustainable methods of synthesis. There are also benefits for cell makers with improvement in processability and additional stabilisation knowledge for battery manufacturers, as well as the consumers that benefit from longer driving ranges and battery life in their EV’s. Figure 1

The Effect of Cellulose Separator Water-Scavenging on Cycle Life in Lithium-Ion Batteries

The presence of water inside a lithium ion (Li-ion) battery causes several interconnected chemical mechanisms that lead to material degradation including transition metal dissolution. [1-4]. As a result, cell performance is reduced, and the cell capacity rapidly fades.To mitigate transition metal dissolution caused by trace water, research groups have proposed various approaches to scavenge and neutralize the water within different components of the cell [4-6]. These methods include using a dehydratable molecular sieve within the cathode active material powder [6], direct dosing of the electrolyte with a water scavenging additive [5], and introducing a metal organic framework with water scavenging properties by mixing it with a polymer binder to create a film for use as a separator. Results from these studies show promise in improving the cycling stability of cells under abuse conditions, such as elevated temperature and high water content in the electrolyte. While these water scavenging techniques show clear benefits to cell capacity retention, they come with the trade-off of higher material cost, more complex production processes, and lower energy density, which have limited their widespread adoption in Li-ion batteries.This study focuses on the use of “cellulose”, a cheap, abundant and naturally dehydrating biopolymer, as a separator material. Cellulose-based separators have been used in Li-ion batteries and shown to be advantageous for capacity retention of the cells. The benefits of the cellulose separators have been attributed to their superior wettability, uniform pore size distribution, high porosity, and low electrical resistance [7-10]. Despite their well-known hydrophilicity, their water scavenging capabilities have not been thoroughly evaluated.In this work, we present new insights into the interaction of water with cellulose-based separator. The water scavenging properties of the cellulose separator are investigated both outside of the battery using the Karl-Fischer Coulometric Titration technique, and inside of the battery through cycling tests. As shown in Figure 1, replacing the conventional polymer-based separator with a cellulose-based nonwoven separator resulted in a significant improvement in cycle life. Furthermore, the water scavenging mechanism of cellulose-based nonwoven separator is studied using surface chemistry characterizations, suggesting water scavenging by the naturally occurring hydrogen bonding sites of cellulose. Additional discussion on drying conditions and the impact of other fiber types are also provided.

Surface Engineering of Ni-Rich Cathode with Spinel Structure for Improved Performance of All-Solid-State Batteries

All-solid-state batteries are emerging as the most promising next-generation batteries due to their ability to achieve high energy density, along with their non-flammable properties. However, all-solid-state batteries face difficulties in commercialization, owing to high interfacial resistance and electrochemical instability at the interface. In particular, the compatibility and contact area issues of the interface between the solid electrolyte and cathode materials are still problematic. To address this issue, we applied a surface treatment in the form of a spinel structure to the Ni-rich cathode material. This surface modification not only improved cycle life by increasing the surface stability of the cathode material but also reduced the internal resistance by creating an ionic conductivity network that facilitated the transport of Li-ions through the cathode. Our results suggest that surface engineering of the Ni-rich cathode has the potential to develop long cycle life and high performance in all-solid-state batteries.