High Energy Density Lithium Batteries Research Articles

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.

Electrochemical performance of CrOx cathode material for high energy density lithium batteries

Electrochemical performance of CrOx cathode material for high energy density lithium batteries

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

Two large barriers are impeding the wide implementation of electric vehicles, namely driving-range and cost, primarily due to the low specific energy and high cost of mono-valence cathodes used in lithium-ion batteries. Iron is the ideal element for cathode materials considering its abundance, low cost and toxicity. However, the poor reversibility of (de)lithiation and low electronic conductivity prevent iron-based high specific energy multi-valence conversion cathodes from practical applications. In this work, a sustainable FeOF nanocomposite is developed with extraordinary performance. The specific capacity and energy reach 621mAhg-1 and 1124Whkg-1 with more than 100 cycles, which triples the specific capacity, and doubles the specific energy of current mono-valence intercalation LiCoO2 . This is the result of an effective approach, combing the nanostructured FeOF with graphene, realized by making the (de)lithiation reversible by immobilizing FeOF nanoparticles and the discharge products over the graphene surface and providing the interparticle electric conduction. Importantly, it demonstrates 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 sustainable conversion materials, eventually overcoming the driving range and cost barriers.

Dual redox-active porous polyimides as high performance and versatile electrode material for next-generation batteries.

Energy storage will be a primordial actor of the ecological transition initiated in the energy and transport sectors. As such, innovative approaches to design high-performance electrode materials are crucial for the development of the next generation of batteries. Herein, a novel dual redox-active and porous polyimide network (MTA-MPT), based on mellitic trianhydride (MTA) and 3,7-diamino-N-methylphenothiazine (MPT) monomers, is proposed for applications in both high energy density lithium batteries and symmetric all-organic batteries. The MTA-MPT porous polyimide was synthesized using a novel environmentally-friendly hydrothermal polymerization method. Rooted in its dual redox proprieties, the MTA-MPT porous polyimide exhibits a high theoretical capacity making it a very attractive cathode material for high energy density battery applications. The cycling performance of this novel electrode material was assessed in both high energy density lithium batteries and light-weight symmetric all-organic batteries, displaying excellent rate capability and long-term cycling stability.

Reversible halogen cathodes for high energy lithium batteries

Lithium halides are attractive as conversion cathodes for potentially high energy density lithium batteries but have not been explored in depth in aprotic electrolytes. In this issue of <i>Joule</i>, Wang and co-workers describe a set of design principles of the electrode and electrolyte to enable the reversibility of lithium halide/graphite mixture cathodes for lithium batteries. By establishing a general rule of liquefaction of the (inter)halogen and rationally designing the electrolyte, they introduced the interhalogen-graphite intercalation compounds as a new family of conversion cathodes for high-energy rechargeable batteries.

Slidable and Highly Ionic Conductive Polymer Binder for High-Performance Si Anodes in Lithium-Ion Batteries.

Silicon is expected to become the ideal anode material for the next generation of high energy density lithium battery because of its high theoretical capacity (4200 mAh g-1 ). However, for silicon electrodes, the initial coulombic efficiency (ICE) is low and the volume of the electrode changes by over 300% after lithiation. The capacity of the silicon electrode decreases rapidly during cycling, hindering the practical application. In this work, a slidable and highly ionic conductive flexible polymer binder with a specific single-ion structure (abbreviated as SSIP) is presented in which polyrotaxane acts as a dynamic crosslinker. The ionic conducting network is expected to reduce the overall resistance, improve ICE and stabilize the electrode interface. Furthermore, the introduction of slidable polyrotaxane increases the reversible dynamics of the binder and improves the long-term cycling stability and rate performance. The silicon anode based on SSIP provides a discharge capacity of ≈1650 mAh g-1 after 400 cycles at 0.5C with a high ICE of upto 92.0%. Additionally, the electrode still exhibits a high ICE of 87.5% with an ultra-high Si loading of 3.84mg cm-2 and maintains a satisfying areal capacity of 5.9 mAh cm-2 after 50 cycles, exhibiting the potential application of SSIP in silicon-based anodes.

A sulfolane-based high-voltage electrolyte with dispersed aggregates for 5 V batteries

High concentrated electrolytes (HCEs) and local high concentrated electrolytes (LHCEs) energize the development of high-energy density lithium batteries, which are attributed to the cation-anion aggregates (AGGs) formed at a high salt concentration that are favorable to form a robust inorganic-derived solid electrolyte interface (SEI) on the lithium surface. However, how to obtain more AGGs at a low salt concentration still faces great challenges. Herein, we report a dispersed AGG electrolyte (DAE) to enhance the content of AGGs at a common salt concentration via two steps: (1) LiPF6, which has a relatively weak dissociation in sulfolane, is chosen to form a large three-dimensional network structure (AGG clusters). (2) the dispersion of AGG clusters into smaller AGGs is achieved by adding hydrofloroether (HFE). By comparing a series of HFEs, we find that HFEs with long chains and high fluorination have a preferable ability to disperse AGGs. As a result, the electrolyte achieves 99.5% Coulomb efficiency and dendrite-free Li anode in LNMO||Li cells with 500 cycles at a high cutoff voltage of 4.95 V. This strategy provides a new way to develop electrolytes for next-generation high-performance batteries.