High Energy Density Lithium Batteries Research Articles

Organic-Inorganic Hybrid Solid Composite Electrolytes for High Energy Density Lithium Batteries: Combining Manufacturability, Conductivity, and Stability.

The deployment of solid and quasi-solid electrolytes in lithium metal batteries is envisioned to push their energy densities to even higher levels, in addition to providing enhanced safety. This article discusses a set of hybrid solid composite electrolytes which combine functional properties with electrode compatibility and manufacturability. Their anodic stability >5V versus Li+/Li and compatibility with lithium metal stem from the incorporated ionic liquid electrolyte, whereas the organic-inorganic hybrid host structure boosts their conductivity up to 2.7mScm-1 at room temperature. The absence of strong acids enables compatibility with porous NMC811 electrodes. Liquid precursor solutions can be readily impregnated into porous electrodes, facilitating cell assembly. Electrolytes containing TFSI- as the only anion have a superior compatibility toward high-voltage positive electrode materials, whereas electrolytes containing both FSI- and TFSI- have a better compatibility toward lithium metal. Using the former as catholyte and the latter as anolyte, NMC811/Li coin cells retain up to 100% of their initial capacity after 100 cycles (0.2C, 3.0-4.4V vs Li+/Li). Because of their unprecedented combination of functional properties, electrode compatibility, and manufacturability, these hybrid solid composite electrolytes are potential candidates for the further development of lithium metal battery technology.

Surface Reconstruction Reduces Internal Stress of Ni-Rich Cathode Particles.

High-voltage Ni-rich layered cathode materials are undoubtedly a powerful driving force for high-energy density lithium batteries. However, residual lithium impurities on the surface of Ni-rich materials can cause more severe side reactions under high-voltage, leading to rapid decay. There is still no reliable mechanistic explanation for this phenomenon. It has been detected that residual alkali on the cathode surface under high voltage can cause obvious side reactions. This side reaction will affect the capacity retention of the material and increase the internal stress of the particles. In addition, the surface reconstruction of Ni-rich cathodes is achieved through simple chemical reactions, turning waste into treasure. The newly generated Ti-based layer not only repairs the structure of the nickel-rich material but also optimizes the material from a dynamic perspective. Removing residual lithium components on the cathode surface effectively reduces the hydrolysis and self-catalytic side reactions of PF6 - at the electrolyte cathode interface and suppresses gas generation during cycling, promoting the application of the next generation of high-energy density Ni-rich layered cathode-based lithium batteries with high-voltage.

All fluorine-free lithium-ion batteries with high-rate capability

Fluorinated compounds, including per- and polyfluoroalkyl substances (PFAS), are crucial in battery technologies for their exceptional thermal and chemical resistance but pose significant environmental and health risks. Facing potential bans by the European Chemicals Agency post-2026, this study introduces non-fluorinated alternatives to meet the needs of high-energy–density lithium batteries in a completely fluorine-free environment. We have replaced traditional fluorinated lithium hexafluorophosphate-based electrolytes and poly(vinylidene fluoride) binders with an optimized lithium perchlorate-based electrolyte offering extended oxidation stability up to 5 V and a newly synthesized aromatic polyamide binder with remarkable binding strength derived from its polar groups (–CONH-, −O=S=O-, and –COOH). This shift demonstrates robust oxidation resistance without fluorine, improving the performance of fluorine-free graphite/NCM811 lithium-ion batteries, which exhibit superior fast-discharging capabilities and cycling stability under 2.8–4.3 V at 1 C, outperforming traditional fluorinated cells. Furthermore, the successful development of an all-fluorine-free 1.5 Ah pouch cell confirms the viability of non-fluorinated materials for high-capacity battery applications.

Glassy Oxides as Positive Electrode Materials for Sustainable and High Energy Density Li-Ion and Na-Ion Batteries: First Attempts to Establish Relationships between Glass Compositions, Physicochemical Characterizations and Electrochemical Properties with Machine Learning and Design of Experiments Approaches

Today, rechargeable lithium-ion batteries (LIBs) represent one of the best alternatives to reduce our dependency on fossil fuels. LIBs are using cathode materials based on polycrystalline oxides or polyanionic compounds [1]. However, their performances can be limited by their crystalline structure when other compounds suffer from metallic dissolution and irreversible phase changes during cycling [2]. To overcome these key shortcomings, implementing glasses or glass-ceramics as cathode materials is an interesting approach [3]. Glasses have a structure composed of more free volume, and, in the literature that is mainly concerning glasses containing Vanadium transition metal, the glasses can so accept a large amount of lithium [4] and easily accommodate structural changes upon lithium ions extraction/insertion [5]. Furthermore, glass production is a scalable process and can be commercially easier to implement than most of synthesis processes of conventional cathode materials.The main objective targeted is to develop high capacity positive electrodes (up to 300mAh/g) for Li-ion batteries based on glassy oxides without critical transition metals such as Cobalt and Vanadium. The ambitious target is to exceed 1000Wh/kg at the active material level and so enable energy densities of 300-350 Wh/kg at the Li-Ion cell level. Additionally, the electrochemical behavior of some alkali-free glass compositions will be evaluated in sodium-ion configuration. The major scientific objective is to correlate the most relevant physicochemical properties of glass with the corresponding electrochemical performances using machine learning approaches or design of experiment methodology. For a better understanding of involved processes, three oxides glass families are studied as promising cathode materials for sustainable and high energy density lithium batteries. These oxides are composed of: i) a glass network-forming element (Si, B, P) leading to the 3 different families, ii) a transition metal (Mn, Fe, ...) and optionally iii) an alkali (Li, Na).The influence of the nature of the transition metal and the polyanionic group corresponding to the network-forming element (PO4, BO3, SiO4) on the electrical properties of the as-prepared glasses measured at different temperatures will be presented mainly for the lithiated compounds. For microstructural characterization, several techniques were coupled such as X-Ray Diffraction (XRD), SEM-EDX, DTA/TGA, Raman, IR and UV-Vis spectroscopies, Electrochemical Impedance Spectroscopy (EIS) and chronoamperometry.Finally, the electrochemical properties in terms of specific capacity, redox potentials, first cycle capacity loss, coulombic and energetic efficiencies of these materials were investigated in coin-cells vs lithium (or sodium) metal electrode. To understand the electrochemical processes involved in these materials at room temperature, SEM-EDX, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Mossbauër Spectroscopy for iron based compounds were coupled and performed on the as-prepared glasses and on ex-situ (after cycling) materials at different electrochemical states of charge.All the generated data and measurements were analyzed by machine learning approach and tools and in some cases compared with a more classical Design of Experiments (DOE) approach. For instance, figure 1 illustrates the contour diagram of first discharge capacities in the mixture diagram of phosphate glasses based on 3 different transition metal oxides. The final goal is to establish more precisely the relationships between the different glassy oxides structures and their electrochemical performances. First results of this important work of elaboration, characterization and data analysis will be presented here. This new study will bring significant elements to optimize both the glass composition and its elaboration conditions to obtain high performance cathode materials without critical materials.[1] Nitta, N. et al., Li-ion battery materials: present and future. Materials Today 18, 252–264 (2015).[2] Tesfamhret, Y. et al., On the Manganese Dissolution Process from LiMn2O4 Cathode Materials. ChemElectroChem 8, 1516–1523 (2021).[3] K. Kercher et al., « Mixed polyanion glass cathodes: Glass-state conversion reactions », J. Electrochem. Soc., vol. 163, no 2, p. A131-A137, 2016, doi: 10.1149/2.0381602jes [4] Afyon, S. et al., New High Capacity Cathode Materials for Rechargeable Li-ion Batteries. Scientific Reports 4, 7113 (2015).[5] Kindle, M. et al., Alternatives to Cobalt. ACS Sustainable Chemistry Engineering 9, 629–638 (2021). Figure 1

Exceptional Rate Performances of Li-Rich Mn-Based Cathodes Enabled by Boron-Based Additives-Driven Self-Optimized Interface.

Li-rich Mn-based cathode material (LRM), as a promising cathode for high energy density lithium batteries, suffers from severe side reactions in conventional lithium hexafluorophosphate (LiPF6)-based carbonate electrolytes, leading to unstable interfaces and poor rate performances. Herein, a boron-based additives-driven self-optimized interface strategy is presented to dissolve low ionic conductivity LiF nanoparticles at the outer cathode electrolyte interface, leading to the optimized interfacial components, as well as the enhanced Li ion migration rate in electrolytes. Being attributed to these superiorities, the LRM||Li battery delivers a high-capacity retention of 92.19% at 1C after 200 cycles and a low voltage decay of 1.08 mV/cycle. This work provides a new perspective on the rational selection of functional additives with an interfacial self-optimized characteristic to achieve a long lifespan LRM with exceptional rate performances.

Solid polymer electrolytes regulated by ion-dipole interactions for high voltage lithium batteries

Solid polymer electrolytes (SPEs) with wide electrochemically stable window and high lithium-ion transference number (tLi+) are a requirement for high energy density lithium batteries. Here, we construct a copolymer electrolyte (PDA) with ether-ester bifunctional groups that exhibits a low highest occupied molecular orbital (HOMO) energy level by in situ polymerization. Compared to the poly(1,3-dioxolane) (PDOL) pure polyether electrolyte, the weakening of the ion-dipole interaction between lithium salt and polymer in the PDA electrolyte promotes the formation of a “weak solvation” structure. Therefore, the electrolyte achieves high oxidative stability (4.6 V vs. Li+/ Li with a standard leakage current of 10 μA), high Li+ transference number (0.60), and importantly, derives a stable LiF-rich composition on high voltage cathode surface. Which ultimately enables stable cycling of Li||LiNi0.5Co0.2Mn0.3O2 (NCM523) batteries at a range of 3.0–4.3 V. This work provides a fundamental understanding of the design of antioxidant SPEs to achieve high energy density lithium batteries.

The synergy mechanism of CsSnI3 and LiTFSI enhancing the electrochemical performance of PEO‐based solid‐state batteries

AbstractLithium metal solid‐state battery is the first choice of batteries for electromobiles and consumer electronic products because of the specific capacity of 3860 mAh g−1 and high electrochemical potential (−3.04 V) of Li metal. Flexible polymer solid electrolytes have become the optimal solution to produce high energy density lithium batteries with arbitrary size and shape. In this work, we introduce a halide perovskite, CsSnI3, into the polyethylene oxide/lithium bis‐(trifluoromethanesuphone)imide (PEO–LiTFSI) polymer matrix. The CsSnI3 could form a LixSn alloy with Li, leading to homogenization of the electric field and Li+‐flux at the interface, Sn atom also bonds with the TFSI− anion to provide more dissociated Li+. Besides that, the I atom could interact with Li to form an electronic insulation with a strong blocking effect on electron tunneling. As a proof of concept, the synergy mechanism of the PEO–LiTFSI–CsSnI3 electrolyte improves the stable cycle life of the symmetric battery to more than 500 h, and the Li+ conductivity raised to 6.1 × 10−4 S cm−1 at 60°C. The application of the “zwitter ions analog” halide perovskite in PEO–LiTFSI provides a new choice among various methods to improve the electrochemical performance of polymer solid‐state batteries.

FeF2-Li Batteries in Ionic Liquid Electrolytes

The electrification of the aviation industry requires secondary batteries that meet strict technical specifications, which cannot be achieved by current lithium-ion cells. A step improvement in stack-level energy densities in addition to safer battery chemistries compatible with operations at temperatures up to 80°C are necessary to minimize water-cooling requirements and their adverse impact on energy density. [1]Lithiation of transition metal fluorides (TMFs) cathodes occurs via a two- or three-electron transfer conversion mechanism, enabling an increase in theoretical energy density by 200% to 300% compared to conventional intercalation compounds. [2]Ionic liquids (ILs) are characterized by their high thermal stability, little to no flammability, and low vapor pressure. [3]Combining TMF cathodes with a lithium metal anode and an IL electrolyte results in a battery with a high energy density, safe cell operation, and high-temperature compatibility suitable for applications in electric aviation. [4, 5]Here we present the progress we have made in the development of secondary FeF2-IL-lithium-metal batteries. Through a systematic investigation of active material particle morphology and carbon composite preparation techniques, we have been able to demonstrate stable capacity retention for over 500 cycles.A post-mortem characterization analysis elucidates the role of the IL in forming stable interphases with both anode and cathode materials and on their ageing mechanism at room and elevated (80°C) temperatures. Viswanathan, V. et al. The challenges and opportunities of battery-powered flight. Nature 601, 519–525 (2022).Wang, L. et al. Li-free Cathode Materials for High Energy Density Lithium Batteries. Joule 3, 2086–2102 (2019).Maton, C., De Vos, N. & Stevens, C. V. Ionic liquid thermal stabilities: Decomposition mechanisms and analysis tools. Chemical Society Reviews 42, 5963–5977 (2013).Xiao, A. W. et al. Understanding the conversion mechanism and performance of monodisperse FeF2 nanocrystal cathodes. Nature Materials 19, 644–654 (2020).Olbrich, L. F., Xiao, A. W. & Pasta, M. Conversion-type fluoride cathodes: Current state of the art. Current Opinion in Electrochemistry 30, 100779 (2021). Figure 1

Promising electric aviation industry and its bright future

There have been rising concerns about the amount of greenhouse gas emissions that commercial aviation produces each year. Greenhouse gases generated by aircraft trap the sunlight in the ozone layer, causing the planet's temperature to rise yearly. Thus, developing more electric aircraft (MEA) and all-electric aircraft (AEA) is crucial to serve as alternatives to traditional fossil-fuel airplanes to avert climate change. Although electric aircraft theoretically provide numerous benefits in improving efficiency, reducing noise levels, and cutting emissions, numerous challenges exist, such as energy density, cost, and power distribution. This paper aims to analyze these challenges and looks for potential technologies or systems, including electromechanical actuators, high energy-density lithium batteries, and superconducting motors, to resolve these challenges. Overall, the electric aviation industry is promising with further improved new technologies. While MEA will become common shortly, there will still be at least two to three decades before AEA establishes ground and become prevalent in the commercial aviation industry.

Promoting homogeneous lithium deposition by facet-specific absorption of CoIn3 for dendrite-free lithium metal anodes

Lithium metal is expected to be an ideal anode material for future high-energy density lithium batteries. However, the uncontrollable growth of lithium dendrites resulting in a short circuit inside the battery and battery failure has become an obstacle to commercializing lithium metal batteries. In this work, a surface with lithiophilic CoIn3 nucleation sites is developed to achieve a uniform lithium deposition by low temperature thermal treatment of super lithiophilic indium foil with three-dimensional (3D) cobalt foam (CoIn3 @CF). The CoIn3 @CF with 3D porous structure provide channels for rapid Li-ions (Li+) transport and inhibit the volume expansion, while the synergistic effect of lithiophilic CoIn3 alloys caused by the multi-facet orientation relationship promote the formation of homogeneous Li+ diffusion. As a result, the CoIn3@CF host exhibits long cycling over 2400 h at 40 mA cm−2/1 mA cm−2 in symmetric cells. Moreover, a full cell with the Li/CoIn3 @CF as anode and LiFePO4 as cathode delivers a columbic efficiency more than 99.3% over 800 cycles. This work provides a new perspective for the design of high energy Li anodes.

Lithiophilic ZnSe nanoparticles/N-doped carbon for high energy density lithium metal batteries

The commercialization of lithium metal anode possessing ultra-high theoretical capacity has been impeded by safety hazards and inadequate cycling lifespan because of the unregulated lithium dendrites. Here, a framework where MOF-derived ZnSe nanoparticles/N-doped carbon nanosheets are attached to 3D flexible carbon cloth (called ZnSe/NC@CC) is developed. This framework functions as a lithium host for mitigating the detrimental effects of lithium dendrites within the cell. The ZnSe and N-doped sites aid in homogenizing lithium nucleation due to the strong lithiophilicity. The ion/electron conducting mixture (Li2Se and Zn) derived from the lithiation of ZnSe is advantageous for the following homogeneous Li+ flux distribution/deposition. Therefore, the Li@ZnSe/NC@CC electrode performs superbly under 1 mA cm−2, with low lithium nucleation overpotential (8 mV) and extended cycling lifespan (2500 h). Moreover, the LiFePO4-based (LFP) cell, utilizing the established anode, achieves an impressive cycling lifespan (over 1200 cycles at 1C, 1C = 170 mAh g−1) and enhanced rate performance (116.7 mAh g−1 at 10C). It is worth mentioning that the cell maintains an excellent capacity retention of 90.3% after 600 cycles even at a low N/P ratio (defined as the ratio of negative to positive capacity) of around 2.2. This research offers valuable insights for creating a dendrite-free anode in high-energy–density lithium batteries.

Solid Polymer Electrolytes with Dual Anion Synergy and Twofold Reinforcement Effect for All-Solid-State Lithium Batteries.

Solid polymer electrolytes (SPEs) have emerged as a viable alternative to traditional organic liquid-based electrolytes for high energy density and safer lithium batteries. Poly(ethylene oxide) (PEO)-based SPEs are considered one of the mainstream SPE materials with excellent dissociation ability of lithium salts. However, the inferior ionic conductivity at room temperature and poor dimensional stability at high temperature limit their utilization. In this work, a semi-interpenetrating polymer network (semi-IPN) forming a precursor based on an ionic liquid (IL) monomer and linear PEO chains were introduced into an electrospun poly(acrylonitrile) (PAN) fibrous mat with subsequent thermal-initiated cross-linking. 1,4-Diazabicyclo [2.2.2] octane (DABCO) and 4-(chloromethyl) styrene were used to synthesize the styrenic-DABCO-based IL monomer with bis(trifluoromethane sulfonyl)imide (TFSI-) or bis(fluoromethane sulfonyl)imide (FSI-) as the anion, named as SDTFSI and SDFSI, respectively. Together, the FSI- and TFSI- anions demonstrate a synergistic effect in providing ion-conductive LiF and Li3N-rich inorganic SEI layer with enhanced lithium dendrite suppression ability. The twofold reinforcement effect is achieved collectively from the semi-IPN structure and the three-dimensional (3D) PAN network that help to construct highly efficient and uniform ion transport channels with excellent flexibility, further suppressing the lithium dendrite growth. The SPEs were dimensionally stable even at elevated temperatures of 150 °C. Moreover, the SPEs show an ionic conductivity of 4.4 × 10-4 S cm-1 at 25 °C and 1.81 × 10-3 S cm-1 at 55 °C and a lithium-ion transference number of 0.56. The favorable electrochemical performance of the SPEs was verified by operating LiFePO4/Li and NMC/Li cells.

In-situ polymerized gel polymer electrolytes for stable solid-state lithium batteries with long-cycle life

The practical application of high energy density lithium batteries is significantly limited by serious safety concerns and chemical instability of traditional organic liquid electrolytes. In this work, polyethylene glycol (PEG) based gel polymer electrolyte (GPE) supported by polyethylene (PE) separator is proposed by in-situ polymerization. The obtained GPE with 50% liquid electrolyte (LE) exhibits an ionic conductivity of 2.22 × 10−4 S cm−1 at 30 °C, a wide electrochemical stability window up to 4.7 V and high lithium ion transference number of 0.502. Furthermore, the GPE displays good interfacial compatibility with lithium anode and the Li//Li symmetric battery with PE supported GPE can cycle stably for 2800 h. In addition, the LiFePO4//Li solid state batteries show outstanding charging/discharging performances at both 30 °C and 60 °C. Particularly, the battery can stable cycle over 1000 cycles at 1 C under 30 °C with capacity retention of 83.36%; meanwhile, it shows a high initial reversible capacity of 149.8 mAh g−1 with excellent cycling stability over 200 cycles at 1 C under 60 °C. This work provides an in-situ polymerized GPE and its promising potential application in lithium metal batteries with a long-cycle life.

Copper Oxide Decorated Carbon Nanofiber Skeleton for Dendrite‐Free Lithium‐Metal Anodes

AbstractLithium metal, possessing a high theoretical capacity, holds great promise as a desirable anode candidate for the next‐generation high energy density lithium batteries. However, the practical implementation of lithium metal faces significant challenges, including dendrite growth and volume expansion. Herein, a carbon nanofiber (CNF) three‐dimensional (3D) current collector was developed, complemented by the addition of copper oxide nanoparticles to the CNF framework, resulting in the creation of a lithiophilic 3D current collector known as CuO‐CNF. Subsequently, a 3D lithium metal composite anode (CuO‐CNF−Li) was fabricated through an electrochemical plating process. The utilization of a 3D structure based on carbon nanofibers provides sufficient space and a stable framework for lithium ion plating, effectively accommodating the substantial volume changes that occur during repetitive Li plating and stripping. The copper oxide nanoparticles loaded onto the CNF serve as active sites for lithium nucleation, facilitating an ordered and uniform plating/stripping process of lithium ions, thereby preventing dendrite formation. Consequently, the CuO‐CNF current collector enables dendrite‐free Li plating/stripping with an average Coulomb efficiency of up to 99 % and a low nucleation overpotential of only 15 mV. Moreover, symmetric cell tests demonstrated an extended lifespan of 2700 h at 2 mA cm−2 for the CuO‐CNF−Li composite anode.

(Invited) The Importance of Modeling Interfacial Phenomena in Electrochemical Systems

Chemical-physical processes at material interfaces drive performance and degradation in various energy and environmental systems, such as high energy density batteries, fuel cells, and electrolyzers. Transport (mass, charge, heat) to and through interfaces combined with reactions on the surface dictate the performance and also the degradation of these systems. To understand the fundamental material behavior of electrochemical systems, and to improve their performance and lifetime meso-scale interfacial modeling is needed that can resolve both the surface phenomena and the transport within the interfacial region. In this talk, I will discuss our research into computational modeling of interfacial and surface phenomena that drive performance in high energy density lithium batteries. Over multiple charge/discharge cycles non-uniform lithium plating and secondary reactions at the interface drive performance degradation and pose safety risks. The interplay between local transport, surface conditions, and operating conditions dictate these interfacial changes. In our work we use multi-phase, meso-scale modeling of the interfacial region to understand the driving forces for these changes and the coupling between physical phenomena to better understand the critical physics at the interface and to design more stable, long lasting interfaces.

Reversible Iron Oxyfluoride (FeOF)-Graphene Composites as Sustainable Cathodes for High Energy Density Lithium Batteries

Two large barriers are impeding the wide implementation of battery electric vehicles, namely driving-range and cost, primarily due to the low specific capacity/energy and high cost of mono-valence cathodes (e.g. LiNi0.8Co0.1Mn0.1O2) used in lithium-ion batteries. Iron is the ideal element of choice for cathode materials considering its abundance, low cost and toxicity. Two fundamental challenges, in particular, the poor reversibility of (de)lithiation and low electronic conductivity, prevent those iron based high specific capacity/energy multi-valence conversion cathodes from practical applications. In this work, we have developed a sustainable FeOF nanocomposite with extraordinary performance. In particular, we were able to reach the theoretical specific capacity of 621 mAh·g-1 and 1,124 Wh·kg-1 specific energy (2.1-valence change/2.1 Li+ stored per unit) and more than 100 cycles with 80% capacity retention at 0.1C (realizing the reversible (de)lithiation), which is 3 times of the specific capacity, and 2 times of the specific energy of current mono-valence intercalation LiCoO2 respectively (i.e., 145 mAh·g-1 and 551 Wh·kg-1). This is the result of an effective approach, combing the nanostructured FeOF with graphene sheets to solve these challenges, realized by (1) making the (de)lithiation reversible by immobilizing FeOF nanoparticles and the discharge products of Fe nanoparticle and LiF over the graphene surface, and sandwiching them between graphene sheets to prevent them from migration and dissolution into electrolytes and (2) providing the inter-particle electric conductivity. In situ high energy synchrotron X-ray absorption spectroscopy (XAS) reveals that this new FeOF composite has a different but reversible (de)lithiation mechanism. Importantly, it demonstrated that introducing small amount of graphene can create new materials with desired properties, opening a new avenue for altering the (de)lithiation process. Such extraordinary performance represents a significant breakthrough in developing the sustainable conversion materials for replacing the intercalation compounds, eventually overcoming the driving range and cost barriers.

High-zeta-potential accelerates interface charge transfer in lithium anodes via MXene-graphdiyne heterojunction layers

Lithium (Li) metal anodes are a crucial part of lithium-based batteries and are highly regarded as a top contender for achieving high-energy–density lithium batteries. However, the development of dendrites and other related issues have significantly impeded their practical applications. Here, we fabricated a MXene (Ti3C2Tx)-graphdiyne heterostructure layer anode with high-zeta-potential (−90 mV) using an electrostatic self-assembly method. The high-zeta-potential can accelerate the interface charge transfer in the lithium deposition process, facilitating the uniform Li nucleation on the surface of anodes. Theoretical simulations further reveal that the high-zeta-potential can not only reduce the lithium ion concentration gradient but also homogenize the electric field in the anodes. Besides, based on first-principles computation, the adsorption energy of lithium atoms on MXene-graphdiyne heterostructure is − 3.4 eV. As a result, a low overpotential of 12.4 mV has been achieved by MXene-graphdiyne layers at 0.05 mA cm−2. Additionally, MXene-graphdiyne-Li anodes display an ultralong cycle life upto 1400 h and good rate capability upto 8 mA cm−2 in symmetric cells. Full cells consisting of MXene-graphdiyne-Li anodes and LiFeO4 cathodes also show stable cyclic properties (300 cycles at 5C).

Advances and Prospects in Improving the Utilization Efficiency of Lithium for High Energy Density Lithium Batteries

AbstractLithium‐ion batteries have attracted much attention in the field like portable devices and electronic vehicles. Due to growing demands of energy storage systems, lithium metal batteries with higher energy density are promising candidates to replace lithium‐ion batteries. However, using excess amounts of lithium can lower the energy density and cause safety risks. To solve these problems, it is crucial to use limited amount of lithium in lithium metal batteries to achieve higher utilization efficiency of lithium, higher energy density, and higher safety. The main reasons for the loss of active lithium are the side reactions between electrolyte and electrode, growth of lithium dendrites, and the volume change of electrode materials during the charge and discharge process. Based on these issues, much effort have been put to improve the utilization efficiency of lithium such as mitigating the side reactions, guiding the uniform lithium deposition, and increasing the adhesion between electrolyte and electrode. In this review, strategies for high utilization efficiency of lithium are presented. Moreover, the remaining challenges and the future perspectives on improving the utilization of lithium are also outlined.

N-Fluorobenzenesulfonimide as a multifunctional electrolyte additive for co-stabilizing dual-electrodes of lithium metal batteries with enhanced electrochemical performance

Lithium metal batteries (LMBs) hold great promise in the next-generation high energy density lithium battery system, yet excessive lithium dendrite growth induces poor cyclability and severe safety hazards of LMBs. Here, a novel bifunctional electrolyte additive, N-Fluorobenzenesulfonimide (NFSI), was developed to highly improve the cyclability and safety of LMBs. Benefiting from lower LUMO and higher HOMO energies, the NFSI additive preferentially reacts with the lithium anode to form stable solid electrolyte interphase (SEI) film to inhibit the electrolyte consumption and lithium dendrite growth upon cycling. Meanwhile, NFSI is also preferentially oxidized to generate a uniform and dense ultrathin cathode-electrolyte interphase (CEI) layer rich in conductive LiF and Li3N on the cathode surface under high voltage. As a result, the Li||Li cells containing 0.1 M NFSI exhibit excellent cycle stability over 1000 h at 0.5 mA cm−2, and the Li||Cu cells give a high Coulombic efficiency of over 94.5% after 100 cycles at 0.5 mA cm−2 for 1 mAh cm−2. Remarkably, the assembled LMBs including Li||LiFePO4 and Li||NMC532 both demonstrate excellent long-term cyclability and high-rate performance when using NFSI-containing electrolyte, meaning that our developed NFSI bifunctional electrolyte additive will present promising potential in enhancing the cycle and rate performance of next-generation LMBs.

Revealing the Effect of High Ni Content in Li-Rich Cathode Materials: Mitigating Voltage Decay or Increasing Intrinsic Reactivity.

Li-rich layeredoxides are considered as one of the most promising cathode materials for secondary lithium batteries due to their high specific capacities, buttheissueofcontinuous voltage decay during cycling hinders their market entry. Increasing the Ni content in Li-rich materials is assumed to be an effective way to address this issue and attracts recent research interests. However, a high Ni content may induce increased intrinsic reactivity of materials, resulting in severe side reactions with the electrolyte. Thus, a comprehensive study to differentiate the two effects of the Ni content on the cell performance with Li-rich cathode is carried out in this work. Herein, it is demonstrated that a properly dosed amount of Ni can effectively suppress the voltage decay in Li-rich cathodes, while over-loading of Ni, on the contrary, can cause structural instability, Ni dissolution, and nonuniform Li deposition during cycling as well as severe oxygen loss. This work offers a deep understanding on the impacts of Ni content in Li-rich materials, which can be a good guidance for the future design of such cathodes for high energy density lithium batteries.