High Energy Density Batteries Research Articles

Thermal distribution evolution model of SEI in lithium metal anodes

Lithium metal batteries are considered an advantageous choice for high energy density batteries due to their extremely high theoretical specific capacity. However, the interface instability has always been the biggest challenge for the commercial development of lithium metal batteries. The evolution mechanism of the thermal field is a key factor affecting the cyclic life during the evolution of lithium metal interfaces. Herein, the interface evolution mechanism for the impact of thermal distribution on Li dendrites is revealed and quantified by the thermal distribution evolution model of the solid electrolyte interphase (SEI). Three influencing factors are outlined as follows: 1) the ratio of the SEI to electrolyte diffusion capability. 2) The SEI diffusion coefficients for both anionic and cationic species. 3) The anisotropy in the SEI. The results indicate that under the appropriate ratio, the temperature gradient at the tip of lithium dendrites and the SEI-electrolyte interface are lower, which is favorable for a more even distribution of heat within the SEI. Additionally, the diffusion of anions can also influence the temperature gradient during the evolution process of lithium dendrites. Furthermore, introducing anisotropy to the SEI can induce lateral growth of lithium dendrites and reduce the temperature gradient at the tip of the lithium dendrites and the SEI-electrolyte interface. This work provides valuable insights for the interface design of lithium metal batteries.

High-entropy and compositionally complex battery materials

The global demand for high energy density batteries, mostly for application in electric vehicles, offering increased durability, safety, and sustainability is growing rapidly. In the past, this demand has been met primarily by the development and/or improvement of new/established battery materials and technologies. The high-entropy design concept—aiming at increasing chemical complexity/occupational disorder—has recently been introduced into the field of electrochemical energy storage. Various high-entropy battery materials that are seemingly capable of outperforming low-entropy counterparts by offering desirable properties have been reported. However, future studies are required to explore if the concept is broadly applicable and can be extended to all types of battery materials, especially those that are of industrial relevance. Herein, we provide a brief overview of the existing high-entropy anodes, cathodes, and solid/liquid electrolytes for use in rechargeable Li- or Na-ion batteries and discuss potential research directions and opportunities.

Ultra-High Temperature Operated Ni-Rich Cathode Stabilized by Thermal Barrier for High-Energy Lithium-Ion Batteries.

The pursuit of high energy density batteries has expedited the fast development of Ni-rich cathodes. However, the chemo-mechanical degradation induced by local thermal accumulation and anisotropic lattice strain is posing great obstacles for its wide applications. Herein, a highly-antioxidative BaZrO3 thermal barrier engineered LiNi0.8Co0.1Mn0.1O2 cathode through an in situ construction strategy is first reported to circumvent the above issues. It is found that the Zr ions are incorporated to Ni-rich material lattice and influence on the topotactic lithiation as well as enhance the oxygen electronegativity through the rigid Zr─O bonds, which effectively alleviates the lattice strain propagation and decreases the excessive oxidization of lattice oxygen for charge compensation. More importantly, the BaZrO3 thermal barrier with an ultra-low thermal conductivity validly impedes the fast heat exchange between electrode and electrolyte to mitigate the severe surface side reactions. This helps an ultra-high mass loading Li-ion pouch cell deliver a specific energy density of 690Wh kg-1 at active material level and an excellent capacity retention of 92.5% after 1400 cycles under 1 C at 25°C. Tested at a high temperature of 55°C, the pouch type full-cell also exhibits 88.7% in capacity retention after 1200 cycles.

Constructing high-toughness polyimide binder with robust polarity and ion-conductive mechanisms ensuring long-term operational stability of silicon-based anodes

Silicon-based materials have demonstrated remarkable potential in high-energy–density batteries owing to their high theoretical capacity. However, the significant volume expansion of silicon seriously hinders its utilization as a lithium-ion anode. Herein, a functionalized high-toughness polyimide (PDMI) is synthesized by copolymerizing the 4,4′-Oxydiphthalic anhydride (ODPA) with 4,4′-oxydianiline (ODA), 2,3-diaminobenzoic acid (DABA), and 1,3-bis(3-aminopropyl)-tetramethyl disiloxane (DMS). The combination of rigid benzene rings and flexible oxygen groups (-O-) in the PDMI molecular chain via a rigidness/softness coupling mechanism contributes to high toughness. The plentiful polar carboxyl (–COOH) groups establish robust bonding strength. Rapid ionic transport is achieved by incorporating the flexible siloxane segment (Si-O-Si), which imparts high molecular chain motility and augments free volume holes to facilitate lithium-ion transport (9.8 × 10−10 cm2 s−1 vs. 16 × 10−10 cm2 s−1). As expected, the SiOx@PDMI-1.5 electrode delivers brilliant long-term cycle performance with a remarkable capacity retention of 85% over 500 cycles at 1.3 A g−1. The well-designed functionalized polyimide also significantly enhances the electrochemical properties of Si nanoparticles electrode. Meanwhile, the assembled SiOx@PDMI-1.5/NCM811 full cell delivers a high retention of 80% after 100 cycles. The perspective of the binder design strategy based on polyimide modification delivers a novel path toward high-capacity electrodes for high-energy–density batteries.

MOF-derived cobalt nanoparticles in silicon suboxide-based anodes for enhanced lithium storage

The ultra-high theoretical capacity of silicon-based (Si) materials makes them promising anode materials for high energy density lithium-ion batteries. Unfortunately, the dramatic volume change (∼300%) and low electrical conductivity of silicon have severely hindered the commercial use of silicon anodes. Silicon suboxide (SiOx) is one of the ideal candidates for high energy density batteries due to its reduced swelling and lower cost as compared to silicon. However, it remains a huge challenge to address the low conductivity, low (initial) coulombic efficiency and apparent volume effects of SiOx. In this paper, SiOx/Co@C composite anode materials loaded with metal Co nanoparticles were uniformly and efficiently prepared by using 3-aminopropyl triethoxysilane (APTES) as silicon source and Co-MOF as Co source via molecular self-assembly strategy. The experimental results and density functional theory (DFT) calculation showed that the catalytic action of embedded Co nanoparticles had activated the silico-oxygen bond of SiOx and the irreversible product Li2O, thereby improving the initial coulombic efficiency (ICE) and enhancing the reversible capacity. At the same time, the metal Co with mechanical rigidity and electrical conductivity alleviated the volume fluctuation during alloying and improved the charge transfer capacity and ion transport rate of the composite. When compared with SiOx@C anodes, SiOx/Co@C-600 composites showed higher initial CE, superior cyclic stability and good rate performance. In particular, the successful matching of the anode with the lithium iron phosphate (LFP) cathode in full cell systems validated the possibility of its practical application. This work provides important insights into the application of Si-based materials in lithium-ion battery electrode materials and the development of high energy density batteries.

Regulating the Electrode-Electrolyte Interfaces of Lithium-High Nickel Batteries via a Multifunctional Additive.

Lithium metal batteries with high nickel ternary (LiNixCoyMn1-x-yO2, x ≥ 0.8) as the cathode hold the promise to meet the demand of next-generation high energy density batteries. However, the unsatisfactory stability of electrode-electrolyte interfaces limits their practical applications. In this work, N-methyl-N-trimethylsilyltrifluoroacetamide (NMTFA) is suggested as a new functional electrolyte additive to stabilize the Li∥LiNi0.9Co0.05Mn0.05O2 chemistry by forming robust and effective electrode-electrolyte interphases, namely the anode-electrolyte interphase (AEI, or conventionally called SEI) and cathode-electrolyte interphase (CEI). The NMTFA-derived SEI/CEI greatly enhances the battery performance that a capacity retention of 82.1% after 200 cycles at 1C charge/discharge is achieved, significantly higher than that without NMTFA addition (52.5%). Moreover, the NMTFA also improves the thermal stability of the electrolyte and inhibits the hydrolysis of LiPF6. This work provides new clues for the optimization of electrolyte formulation for lithium-high nickel batteries through modulating interfaces.

Solid Electrolyte Interphase on Lithium Metal Anodes.

Lithium metal batteries (LMBs) represent the most promising next-generation high-energy density batteries. The solid electrolyte interphase (SEI) film on the lithium metal anode plays a crucial role in regulating lithium deposition and improving the cycling performance of LMBs. In this review, we comprehensively present the formation process of the SEI film, while elucidating the key properties such as electronic conductivity, ionic conductivity, and mechanical performance. Furthermore, various approaches for constructing the SEI film are discussed from both electrolyte regulation and artificial coating design perspectives. Lastly, future research directions along with development recommendations are also provided. This review aims to provide possible strategies for the further improvement of SEI film in LMBs and highlight their inspiration for future research directions.

Accelerated Selective Li+ Transports Assisted by Microcrack-Free Anionic Network Polymer Membranes for Long Cyclable Lithium Metal Batteries.

Rechargeable Li metal batteries have the potential to meet the demands of high-energy density batteries for electric vehicles and grid-energy storage system applications. Achieving this goal, however, requires resolving not only safety concerns and a shortened battery cycle life arising from a combination of undesirable lithium dendrite and solid-electrolyte interphase formations. Here, a series of microcrack-free anionic network polymer membranes formed by a facile one-step click reaction are reported, displaying a high cation conductivity of 3.1 × 10-5 S cm-1 at high temperature, a wide electrochemical stability window up to 5V, a remarkable resistance to dendrite growth, and outstanding non-flammability. These enhanced properties are attributed to the presence of tethered borate anions in microcrack-free membranes, which benefits the acceleration of selective Li+ cations transport as well as suppression of dendrite growth. Ultimately, the microcrack-free anionic network polymer membranes render Li metal batteries a safe and long-cyclable energy storage device at high temperatures with a capacity retention of 92.7% and an average coulombic efficiency of 99.867% at 450 cycles.

Conformal 3D Li/Li13Sn5 Scaffolds Anodes for High-Areal Energy Density Flexible Lithium Metal Batteries.

Achieving a high depth of discharge (DOD) in lithium metal anodes (LMAs) is crucial for developing high areal energy density batteries suitable for wearable electronics. Yet, the persistent growth of dendrites compromises battery performance, and the significant lithium consumption during pre-lithiation obstructs their broad application. Herein, A flexible 3D Li13Sn5 scaffold is designed by allowing molten lithium to infiltrate carbon cloth adorned with SnO2 nanocrystals. This design markedly curbs the troublesome dendrite growth, thanks to the uniform electric field distribution and swift Li+ diffusion dynamics. Additionally, with a minimal SnO2 nanocrystals loading (2wt.%), only 0.6wt.% of lithium is consumed during pre-lithiation. Insights from in situ optical microscope observations and COMSOL simulations reveal that lithium remains securely anchored within the scaffold, a result of the rapid mass/charge transfer and uniform electric field distribution. Consequently, this electrode achieves a remarkable DOD of 87.1% at 10mA cm-2 for 40mAh cm-2. Notably, when coupled with a polysulfide cathode, the constructed flexible Li/Li13Sn5@CC||Li2S6/SnO2@CC pouch cell delivers a high-areal capacity of 5.04mAh cm-2 and an impressive areal-energy density of 10.6mWh cm-2. The findings pave the way toward the development of high-performance LMAs, ideal for long-lasting wearable electronics.

Ultra-stable dendrite-free Na and Li metal anodes enabled by tin selenide host material

Lithium/sodium metal anodes are considered promising candidates to realize high-energy–density batteries because of their high theoretical specific capacity and low potential. However, their cycling stability are hindered by uncontrolled dendrites growth. Herein, SnSe nanoparticles are tightly anchored on the fiber of carbon cloth (CC) to construct SnSe@CC host material in order to control Li/Na nucleation behavior and restrain dendrites growth. It is demonstrated that the alloying product of Li15Sn4/Na15Sn4 with strong metal affinity can provide abundant active nucleation sites, and three-dimensional structure of CC host can significantly decrease the local electric current, thereby guiding homogeneous metal deposition without Li and Na dendrites. Meanwhile, the conversion product of Li2Se/Na2Se will uniformly cover on the surface of metal to serve as ultra-stable solid state interface film. As a result, high-capacity Li metal anode (20 mAh·cm−2) and Na metal anode (10 mAh·cm−2) can work steadily with ultra-long lifespans over 5000 and 6000 h with low overpotentials of 7 mV and 141 mV, respectively. Moreover, the assembled Li and Na metal full batteries exhibit superior electrochemical performances, confirming the practicability of metal anode confined in composite host. Such a strategy of conversion-alloying-type materials as hosts opens up a new path for dendrite-free metal anode electrode.

Rational construction Ag/LiF/sulfide rich protective layer for remarkably enhancing the stability of Li metal anodes

Li metal is a promising anode material for high-energy–density batteries due to its high theoretical capacity and low redox potential. However, both the uncontrolled Li dendrite growth and unstable solid electrolyte interphase (SEI) layer restricts its large-scale practical applications. Herein, an artificial protective layer consisting of Ag nanoparticles, lithium fluoride (LiF) and sulfide are innovatively designed and fabricated via the in-situ chemical reaction between Ag(I) trifluoromethylthiolate (AgSCF3) and Li metal. Density functional theory (DFT) results indicate that Ag nanoparticles have a high binding energy with Li atom and LiF/sulfide have wide band gap, which would provide plenty of nucleation sites for Li+ and reduce the direct contact between inner Li metal and the electrolyte. The co-existence of Ag and LiF/sulfide results in a strong synergistic effect, and this is confirmed by the systematical comparison with single modified Ag-Li and double modified F/S-Li anodes. Benefitting from this synergistic effect, the Ag/F/S-Li symmetrical cells can stably work for 2000 h with low-voltage hysteresis at current density of 1 mA cm−2. Full cells assembled with LiCoO2 (LCO) and LiFePO4 (LFP) cathodes displays much better long‐term cycle performance when the Ag/F/S-Li anode is applied. Furthermore, this Ag/F/S-Li modification can significantly enhance discharge capacity, rate performance, as well as energy density of Li(or LiB alloy)||MnO2 primary cells. This promising work promotes the practical application of Li metal and provides new insight into the protective layer design in stable Li metal batteries.

A simple route to functionalized porous carbon foams from carbon nanodots for metal-free pseudocapacitors.

The development of potent pseudocapacitive charge storage materials has emerged as an effective solution for closing the gap between high-energy density batteries and high-power density and long-lasting electrical double-layer capacitors. Sulfonyl compounds are ideal candidates owing to their rapid and reversible redox reactions. However, structural instability and low electrical conductivity hinder their practical application as electrode materials. This work addresses these challenges using a fast and clean laser process to interconnect sulfonated carbon nanodots into functionalized porous carbon frameworks. In this bottom-up approach, the resulting laser-converted three-dimensional (3D) turbostratic carbon foams serve as high-surface-area, conductive scaffolds for redox-active sulfonyl groups. This design enables efficient faradaic processes using pendant sulfonyl groups, leading to a high specific capacitance of 157.6 F g-1 due to the fast reversible redox reactions of sulfonyl moieties. Even at 20 A g-1, the capacitance remained at 78.4% due to the uniform distribution of redox-active sites on the graphitic domains. Additionally, the 3D-tsSC300 electrode showed remarkable cycling stability of >15 000 cycles. The dominant capacitive processes and kinetics were analysed using extensive electrochemical characterizations. Furthermore, we successfully used 3D-tsSC300 in flexible solid-state supercapacitors, achieving a high specific capacitance of up to 17.4 mF cm-2 and retaining 91.6% of the initial capacitance after 20 000 cycles of charge and discharge coupled with 90° bending tests. Additionally, an as-assembled flexible all-solid-state symmetric supercapacitor exhibits a high energy density of 12.6 mW h cm-3 at a high power density of 766.2 W cm-3, both normalized by the volumes of the full device, which is comparable or better than state-of-the-art commercial pseudocapacitors and hybrid capacitors. The integrated supercapacitor provides a wide potential window of 2.0 V using a serial circuit, showing great promise for metal-free energy storage devices.

Design Principle of Disordered Rocksalt Type Overlithiated Anode for High Energy Density Batteries

Rechargeable lithium-ion batteries with high energy density and fast-charging capability are vital for commercial application. Disordered rocksalt (DRX) materials with a cation/anion ratio greater than one, achieved through additional lithium...

Tuning wettability of gallium-based liquid metal anode for lithium-ion battery via a metal mixing strategy

Exploring highly stable alloy-type anodes for rechargeable lithium batteries is urgent with the ever-increasing demands for high energy density batteries. The liquid metal (LM)-based anodes demonstrate great potential in advanced lithium-ion batteries due to their high energy densities and self-healing performance. However, its high surface tension leads to poor wettability towards the current collector and higher interfacial contact resistance. In this study, we developed a new free-standing LM-based anode LM-W10/Cu foil with good wettability and machinability by mixing high-melting-point tungsten (W) nanoparticles. It greatly improves the inherent defects of poor interfacial contact and lithium diffusion kinetics between the LM and current collectors, reduces the tedious and costly electrode manufacturing process, and regulates lithium deposition behaviors. And this metal mixing strategy has a negligible effect on the self-healing nature of LM. Symmetric cells of LM-W10/Cu foil anodes displayed a low overpotential (~13 mV) and cycled stably for more than 8,000 h (4,000 cycles) at 0.5 or 1 mA/cm2; full cells coupled with LiFePO4 cathode showed a high capacity retention of 95.15% after 150 cycles.

Novel Electrolyte Development for In Situ Formed Li-Metal Batteries Using Amplified Solid Electrolyte Interphase and Plating Investigations

Li-metal anodes can provide high energy density battery configurations, but their practical use is hindered by safety concerns and poor efficiencies due to non-ideal lithium plating. In utilizing ultra-low areal plating capacities (0.08 mAh cm−2, LCP) within Li-metal half-cells, it was found that the initial formation efficiency of the SEI can be amplified and correlated with initial losses and capacity fade over time under higher areal plating capacities (2.5 mAh cm−2, 4.0 mAh cm−2, and 6.5 mAh cm−2) within an in-situ formed anodeless LCO configuration. Herein, these techniques have been utilized to introduce and optimize novel fluoroganosiyl (FOS) based dual salt electrolytes for use in in-situ formed Li-metal batteries, achieving initial cycling loss of <3% (at 4.0 mAh cm−2). Further characterization of the functional benefit of this electrolyte was elucidated using XPS surface analysis, revealing unique Li-C-N, Li3N, Si, and B-N chemistries that likely contribute to the formation of a robust SEI.

Activating the electrode–electrolyte interface via a ZnO@black phosphorus modulation layer for dendrite-free Li metal anodes

ZnO@BP modulation layer promoting uniform Li deposition.

Constructing an ultrathin, multi-functional polymer electrolyte for safe and stable all-solid-state batteries

The ever-increasing demand for safe and high energy density batteries urges the exploration of ultrathin, lightweight and high ionic-conducting solid electrolytes. Solid polymer electrolytes (SPEs) with high flexibility, reduced interfacial...

Mechanism and solutions of lithium dendrite growth in lithium metal batteries

Inhibiting lithium dendrite is a big challenge for developing lithium metal batteries. The work reviews possible mechanisms of lithium dendrite growth, discuses effective strategies for inhibiting lithium dendrites and proposes future direction.

Fluorinated organic compounds as promising materials to protect lithium metal anode: a review

The lowest electrode potential and remarkable theoretical specific capacity of lithium (Li) metal make it a promising choice for next-generation high-energy density batteries. However, the practical application of lithium metal anodes (LMAs) faces several significant challenges due to their unwanted reactions with the electrolyte to continuously form Li dendrites. These issues significantly hinder both electrochemical performance and safety. To overcome these challenges, fluorinated organic materials (FOMs), with their unique chemical and physical properties, offer an exciting avenue for enhancing the cycle stability and energy density of batteries. This is attributed to their higher electrolytic window and chemical stability. This review would provide a comprehensive overview of the crucial role played by FOMs in safeguarding LMAs, such as F-containing electrolyte engineering, separator modification, and artificial solid electrolyte interface (SEI). Additionally, it intends to explore the challenges and latest advances in this domain, with the ultimate objective of offering insights and forward-looking perspectives for future research initiatives in related areas.

3D Printed Freestanding Electrodes for High Energy Density Batteries

The global surge in energy consumption, as well as a rise in greenhouse gases, has created an urgent need for high-capacity battery materials to store intermittent, renewable energy sources such as wind and solar. Directly increasing electrode mass loading using the traditional slurry coating fabrication process introduces unavoidable issues such as slowed kinetics and thermal degradation. Freestanding electrodes are a great alternative as they eliminate the need for inactive components (i.e., binder, additive carbon, and current collector) and shorten the fabrication process. In this work, carbon microlattice templates are designed and fabricated through the use of 3D stereolithography, which allows for design flexibility of any shape or geometry, followed by pyrolysis to create porous hard carbon. These hard-carbon templates are then subjected to a ferrocene/sulfur reaction to grow iron sulfide that serves as active material, which has a theoretical specific capacity higher than that of commercial graphite. The design utilizes controlled microchannels that facilitate ion transport through charging and discharging cycles. The addition of FeS led to a specific capacity of 1204.2 mAh g-1 during cycle two with a current density of 500 mA g-1, which is much higher than that achieved with the control carbon template (≈37.3 mAh g-1 at 300 mA g-1). These results will advance the development of composite electrodes as well as shine light on the immense potential to develop high energy density batteries utilizing 3D printing.