High Energy Density Rechargeable Batteries Research Articles

Jointly Improving Anionic-Cationic Redox Reversibility of Lithium-Rich Manganese-Based Cathode Materials by N Surface Doping.

The lithium-rich manganese-based layer oxide (LRMO) with high specific capacity (∼300 mAh g-1) and economic feasibility is accepted as the cathode material for high energy density rechargeable batteries. Accompanied by the additional anionic redox reactions during the initial charging process, LRMO presents oxygen release, sluggish Li+ diffusion, and irreversible transition metal ion (TM) migration, which is responsible for its severe structural deterioration and rapid capacity/voltage decay. Here, the N doping strategy is proposed via feasible treatment of oxygen-vacancy-containing Li1.16Ni0.21Mn0.63O2-δ (LNMO) particles. The as obtained LNMO-N samples demonstrate doping N, partially reduced Mn/Ni cations, and oxygen vacancies on the surface. The DFT calculations and experimental results demonstrate that N replacing the crystal oxygen sites on the surface reduces the energy barrier for diffusion, thereby enhancing the kinetics of Li+ diffusion and improving the reversibility of transition metal migration. Furthermore, N doping induces stacking faults and a more flexible structure. Therefore, LNMO-N exhibits a significantly improved anionic-cationic redox reaction reversibility with a high discharge specific capacity of 296.6 mAh g-1 at 20 mA g-1 within the range of 2.0 to 4.8 V and an impressive initial Coulombic efficiency of 85.9%. Moreover, the rate capability is obviously improved with a remarkable capacity of 215.1 mAh g-1 at 200 mA g-1 in 200 cycles with a capacity retention of 72.52% and exceptional performance of 141.4 mAh g-1 even at a higher current density of 1000 mA g-1.

Lithiophilic ZnCu alloy sites on copper current collector for high performance Li metal anode

Lithium (Li) metal has been widely regarded as the optimal anode material for the high-energy density rechargeable batteries, due to its ultrahigh theoretical specific capacity and lowest electrochemical potential. However, the formation of Li dendrites presents a significant safety concern, which limits its practical application. In this paper, to address this issue, an efficient and cost-effective strategy was proposed to prepare a zinc-copper composite collector (ZCC) with outstanding electrochemical performance, which can effectively suppress the formation of lithium dendrites. The lithophilic surface with ZnCu alloy nanoparticles was achieved through physical vapor deposition followed by annealing treatment. The ZCC collector enables dendrite-free deposition of Li due to its negligible nucleation overpotential. Even at high area capacity of 3 mAh cm−2 at 1 mA cm−2 in half-cells, the ZCC exhibits exceptional cycling performance and high coulomb efficiency. Preloaded with Li, the composite electrode (Li/ZCC) delivers an enhanced lifespan with low overpotential evidently. Matched with LiFePO4 (LFP) cathode, LFP||Li/ZCC full cells reveal a superior cycling stability with enhanced capacity retention of 85 % (after 1000 cycles at 1 C) and 87 % (after 800 cycles at 3 C) respectively.

Performance of a combined electrotrophic and electrogenic biofilm operated under long-term, continuous cycling.

Evaluate electrochemically active biofilms as high energy density rechargeable microbial batteries toward providing persistent power in applications where traditional battery technology is limiting (, remote monitoring applications). Here we demonstrated that an electrochemically active biofilm was able to store and release electrical charge for alternating charge/discharge cycles of up to 24h periodicity (50% duty cycle) with no significant decrease in average current density (0.16 ± 0.04 A/m2) for over 600days. However, operation at 24h periodicity for > 50days resulted in a sharp decrease in the current to nearly zero. This current crash was recoverable by decreasing the periodicity. Overall, the coulombic efficiency remained near unity within experimental error (102 ± 3%) for all of the tested cycling periods. Electrochemical characterization here suggests that electron transfer occurs through multiple routes, likely a mixture of direct and mediated mechanisms. These results indicate that bidirectional electrogenic/electrotrophic biofilms are capable of efficient charge storage/release over a wide range of cycling frequency and may eventually enable development of sustainable, high energy density rechargeable batteries.

A Li3P nanoparticle dispersion strengthened ultrathin Li metal electrode for high energy density rechargeable batteries

A Li3P nanoparticle dispersion strengthened ultrathin Li metal electrode for high energy density rechargeable batteries

Surface Chemistry Regulated Gradient Multi-Component Solid Electrolyte Interphase for 460 Wh kg-1 Lithium Metal Pouch Cell

Lithium (Li) metal is an ideal anode for high energy density rechargeable Li batteries. However, parasitic reactions and uneven native oxide layer on surface led to uncontrollable Li deposition and...

Evaluation of performance metrics for high energy density rechargeable lithium-oxygen batteries.

The demand for practical implementation of rechargeable lithium-oxygen batteries (LOBs) has grown owing to their extremely high theoretical energy density. However, the factors determining the performance of cell-level high energy density LOBs remain unclear. In this study, LOBs with a stacked-cell configuration were fabricated and their performance evaluated under different experimental conditions to clarify the unique degradation phenomenon under lean-electrolyte and high areal capacity conditions. First, the effect of the electrolyte amount against areal capacity ratio (E/C) on the battery performance was evaluated, revealing a complicated voltage profile for an LOB cell operated under high areal capacity conditions. Second, the impact of different kinds of gas-diffusion layer materials on the "sudden death" phenomenon during the charging process was investigated. The results obtained in the present study reveal the importance of these factors when evaluating the performance metrics of LOBs, including cycle life, and round-trip energy efficiency. We believe that adopting a suitable experimental setup with appropriate technological parameters is crucial for accurately interpreting the complicated phenomenon in LOBs with cell-level high energy density.

Exploring the Capability of Framework Materials to Improve Cathodes’ Performance for High‐energy Lithium‐ion Batteries

AbstractLithiated transition metal oxides are the most important cathode materials for lithium‐ion batteries. Many efforts have been devoted in recent years to improving their energy density, stability, and safety, as demonstrated by thousands of publications. However, the commercialization of several promising materials is limited due to obstacles like stability limitations. To overcome the limitations of energetically high‐voltage or high‐capacity cathode materials, unconventional solutions for their surface engineering were suggested; among them, metal–organic frameworks (MOFs) and zeolites have been employed. MOFs possess favorable characteristics for stabilization goals, including manageable structures, topological control, high porosity, large surface area, and low density. This review article explores promising strategies for improving the electrochemical behavior of favorable cathode materials through surface modifications by using MOFs and zeolites. Investigating the potential of this frameworks‐based surface engineering for high energy density batteries’ electrodes is essential for optimal control of their surface chemistry. It may be highly effective to upgrade the performance of high‐energy cathode materials, thus extending the practical use of very high energy density rechargeable batteries.

Exploring the effect of lithium halide artificial SEI on the electrochemical performance of lithium metal batteries

The urgent need for high-energy–density rechargeable batteries is driving lithium (Li) metal as a promising anode material. However, the conventional solid electrolyte interface (SEI) on lithium metal suffers from elevated interfacial impedance, poor mechanical properties, and non-uniform Li+ flux. Previously, LiF has been proven to be an effective component of the SEI protecting lithium metal. However, this is a rarely reported application of LiCl and LiBr in SEI. Herein, we design SEI containing lithium halide in different ratios (LiF0.8Cl0.1Br0.1, LiF0.33Cl0.33Br0.33, LiCl, LiBr) to investigate the action laws of lithium halide in SEI. It has been shown that the performance of SEI containing lithium halide against lithium anode increases with the LiF content in the SEI. The higher the proportion of LiF in SEI, the better the cycle life and stability of Li-Li symmetric cells, and the higher the initial capacity and the capacity retention of LFP-Li full cells. The symmetric cell with LiF0.8Cl0.1Br0.1@Li has the smallest average polarization voltage (about ± 30 mV) and long cycle life of up to 1000 h. LiFePO4||LiF0.8Cl0.1Br0.1@Li cells have the highest initial capacity (127.4 mAh/g), and still had 83.6 % capacity retention after 1000 cycles at 2C.

High Performance Hybrid Aqueous Li/NiCl2 Rechargeable Batteries with Water‐Stable High Lithium‐Ion Conductivity Solid Electrolyte

AbstractThe feasibility of a novel high specific energy and power density rechargeable aqueous lithium battery with a lithium anode, an aqueous NiCl2 catholyte, and a water‐stable high lithium‐ion conducting solid electrolyte separator was investigated. Water‐stable Li1.6Al0.4Ge0.2Ti1.4(PO4)3‐10 wt % TiO2‐3 wt % LiCl ⋅ H2O‐expoxy resin (LAGTP‐T), which has a high lithium‐ion conductivity of 10−3 S cm−1 at 25 °C and an excellent bending strength of 150 N mm−2, was used as the separator between the lithium anode and the aqueous NiCl2 catholyte in the rechargeable aqueous Li/NiCl2 battery. The battery was successfully operated at 5 mA cm−2 and room temperature. The estimated specific energy density of the battery based on the cell components of a 200 μm thick LAGTP‐T, a lithium anode, current collectors, and an interlayer electrolyte is higher than that of the conventional lithium‐ion battery with a carbon anode and a LiCoO2 cathode at a high specific capacity of more than 15 mAh cm−2, and that at 50 mAh cm−2 is two times higher than that of the lithium‐ion battery.

InPc-modified gel electrolyte based on in situ polymerization in practical high-loading lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are currently being investigated as a potential candidate for high-energy–density rechargeable batteries. However, the notorious shuttle effect and uncontrolled dendrite growth posed problems for the practical applications of LSBs. Here, a new solid polymer electrolyte (SPE) was developed by in-situ polymerization of 1,3-dioxolane (DOL) in the presence of a multifunctional indium phthalocyanine (PDOL@InPc). The InPc endows the SPE with improved ionic conductivity and merit inhibition of the shuttle effect, in addition to being an effective additive for inducing uniform Li deposition by reconstructing the electric field at the interface. The characteristics of ionic migration in PDOL@InPc were quantified, and agreement between experiment and simulation established a relationship between macroscopic characteristics and molecular-level processes. The interfacial side reaction was controlled by the PDOL@InPc electrolyte, which also improved the distribution of the Li+ flux for dense Li deposition. Li symmetrical batteries designed with PDOL@lnPc can withstand a current density of up to 0.5 mA cm−2 and cycle reliably for 1500 h. The PDOL@InPc electrolyte displayed a high ionic conductivity at room temperature of 3.7 mS cm−1 and a significant Li+ transference number of 0.63. The resulting Li-S battery (Li|PDOL@lnPc|Sulfur) delivered a significant 325.5 Wh kg−1 of energy density at 0.2 C (1 C = 1000 mA g−1) at the level of the multilayer-pouch cell under an extremely low electrolyte of 3.5 g g−1Sulfur and high loading of 8.0 mg cm−2. This work provides a feasible strategy for the widespread implementation of LSBs with increased safety and a longer lifetime.

Review of Design Routines of MXene Materials for Magnesium-Ion Energy Storage Device.

Renewable energy storage using electrochemical storage devices is extensively used in various field applications. High-power density supercapacitors and high-energy density rechargeable batteries are some of the most effective devices, while lithium-ion batteries (LIBs) are the most common. Due to the scarcity of Li resources and serious safety concerns during the construction of LIBs, development of safer and cheaper technologies with high performance is warranted. Magnesium is one of the most abundant and replaceable elements on earth, and it is safe as it does not generate dendrite following cycling. However, the lack of suitable electrode materials remains a critical issue in developing electrochemical energy storage devices. 2D MXenes can be used to construct composites with different dimensions, owing to their suitable physicochemical properties and unique magnesium-ion adsorption structure. In this study, the construction strategies of MXene in different dimensions, including its physicochemical properties as an electrode material in magnesium ion energy storage devices are reviewed. Research advancements of MXene and MXene-based composites in various kinds of magnesium-ion storage devices are also analyzed to understand its energy storage mechanisms. Finally, current opportunities, challenges, and future prospects are also briefly discussed to provide crucial information for future research.

High-Capacity Rechargeable Li/Cl2 Batteries with Graphite Positive Electrodes.

Developing new types of high-capacity and high-energy density rechargeable batteries is important to future generations of consumer electronics, electric vehicles, and mass energy storage applications. Recently, we reported ∼3.5 V sodium/chlorine (Na/Cl2) and lithium/chlorine (Li/Cl2) batteries with up to 1200 mAh g-1 reversible capacity, using either a Na or a Li metal as the negative electrode, an amorphous carbon nanosphere (aCNS) as the positive electrode, and aluminum chloride (AlCl3) dissolved in thionyl chloride (SOCl2) with fluoride-based additives as the electrolyte [Zhu et al., Nature, 2021, 596 (7873), 525-530]. The high surface area and large pore volume of aCNS in the positive electrode facilitated NaCl or LiCl deposition and trapping of Cl2 for reversible NaCl/Cl2 or LiCl/Cl2 redox reactions and battery discharge/charge cycling. Here, we report an initially low surface area/porosity graphite (DGr) material as the positive electrode in a Li/Cl2 battery, attaining high battery performance after activation in carbon dioxide (CO2) at 1000 °C (DGr_ac) with the first discharge capacity ∼1910 mAh g-1 and a cycling capacity up to 1200 mAh g-1. Ex situ Raman spectroscopy and X-ray diffraction (XRD) revealed the evolution of graphite over battery cycling, including intercalation/deintercalation and exfoliation that generated sufficient pores for hosting LiCl/Cl2 redox. This work opens up widely available, low-cost graphitic materials for high-capacity alkali metal/Cl2 batteries. Lastly, we employed mass spectrometry to probe the Cl2 trapped in the graphitic positive electrode, shedding light into the Li/Cl2 battery operation.

(Invited) A Micelle Electrolyte Enabled By Fluorinated Ether Additives for Polysulfide Suppression, High Voltage Cathode, and Li Metal Anode Stabilization

The Li-S battery is a promising next-generation technology due to its high theoretical energy density (2600 Wh/kg) and low active material cost. However, poor cycling stability and coulombic efficiency caused by polysulfide dissolution have proven to be major obstacles for a practical Li-S battery implementation. In this work, we develop a novel strategy to suppress polysulfide dissolution using hydrofluoroethers (HFEs) with bi-functional, amphiphlic surfactant-like design: a polar lithiophilic “head” attached to a fluorinated lithiophobic “tail.” A unique solvation mechanism is proposed for these solvents whereby dissociated lithium ions are readily coordinated with lithiophilic “head” to induce self-assembly into micelle-like complex structures. Complex formation is verified experimentally by changing the additive structure and concentration using small angle X-ray and neutron scattering. These HFE-based electrolytes are found to prevent polysulfide dissolution and to have excellent chemical compatibility with lithium metal: Li||Cu stripping/plating tests reveal high coulombic efficiency (>99.5%), modest polarization, and smooth surface morphology of the uniformly deposited lithium. Li-S cells are demonstrated with 1395 mAh/g initial capacity and 71.9% retention over 100 cycles at >99.5% efficiency—evidence that the micelle structure of the amphiphilic additives in HFEs can prohibit polysulfide dissolution while enabling facile Li+ transport and anode passivation. In addition, this type of electrolytes is also stable toward high voltage cathode to enable a lithium metal anode and high voltage cathode high-energy density rechargeable lithium battery.

LiF-rich and self-repairing interface induced by MgF2 engineered separator enables dendrite-free lithium metal batteries

Lithium metal batteries (LMBs) are promising for high-energy density rechargeable batteries while suffer from uncontrolled dendrites growth and unstable solid electrolyte interface (SEI) layer on the surface of lithium (Li) metal anodes. In this study, a facile and low-cost strategy is proposed to enable dendrite-free and long-life LMBs by coating MgF2 onto commercial polyethylene separator. The composite separator possesses excellent wettability and high thermal stability. When the MgF2 coating contacts Li metal anode directly, an artificial SEI layer is in-situ formed due to the spontaneously reaction of MgF2 and Li metal, which is composed of LiF and lithiophilic Mg. More importantly, a small amount of dissolved MgF2 can fill the micro-gaps between un-contact MgF2 coating and Li anode and repair the tiny cracks in the SEI generated during repeated charge–discharge process. Hence, a continuous SEI layer is formed throughout the entire surface of Li metal anode with lithiophilic, LiF-rich and self-repairing capabilities, protecting Li metal anode, reducing the nucleation overpotential, promoting smooth Li plating and inhibiting Li dendrites growth. The Li||Li symmetric cells, Cu||Li asymmetric cells and full cells with the MgF2 coated separators delivers significantly enhanced coulombic efficiency and cycle life in both ether-based and carbonate-based electrolyte. This design of artificial LiF-rich SEI with self-repairing capability by separator engineering paves a new insight for the application of alkali metal batteries.

Inverse-opal structured TiO2 regulating electrodeposition behavior to enable stable lithium metal electrodes

Lithium metal anode is almost the ultimate choice for high-energy density rechargeable batteries, but its uneven electrochemical dissolution-deposition characteristics lead to poor cycle stability and lithium dendrites safety problems. The fundamental solution to the problems is to interfere electrodeposition process of lithium metal so that it can be carried out reversibly and stably. In this work, an inverse-opal structured TiO2 membrane with a thickness of only ∼1 μm is designed to regulate the electrodeposition behavior of lithium metal, in which the ordered channels homogenize mass transfer process, the anatase TiO2 walls of the ion channels reduce desolvation barrier of solvated lithium-ions, and the spherical cavities with a diameter of ∼300 nm confine migration of the adsorbed lithium atoms during electrocrystallization to diminish overpotential of lithium. These systematic effects cover and essentially change the whole process of electrodeposition of lithium metal and eliminate the possibility of lithium dendrite formation. The as-obtained lithium metal electrode delivers a Coulombic efficiency of 99.86% in the 100th cycle, and maintains a low deposition overpotential of 0.01 V for 800 h.

Janus-faced graphene substrate stabilizes lithium metal anode

The dendrite growth and irreversibility of lithium (Li) metal anode seriously hinders the wide-scale application of high-energy–density rechargeable batteries. Here, we report a thin Janus-faced graphene substrate, consisting of lithiophilic-lithiophobic faces separately, for Li plating/stripping. The visualized analysis demonstrates that the unique Janus-faced graphene structure provides different lithiophilic sites and pore channels to steer the Li electrodeposition and suppress the dendrite growth. As expected, the Janus-faced graphene anode achieves long-term Li plating/stripping with high Coulombic efficiency, small polarization and stable cycling throughout the symmetry, asymmetry and LiFePO4 full cells. Such an encouraging strategy for reversible Li plating/stripping provides a promising way to design long-life carbon-base anode materials for Li metal batteries.

Dendrite‐Free Lithium Deposition and Stripping Regulated by Aligned Microchannels for Stable Lithium Metal Batteries

AbstractLi metal is the ultimate choice for the anode in next‐generation high energy density rechargeable batteries. However, undesired dendrite growth, dead Li formation, and a large volume change of the lithium metal anode lead to severe safety hazards such as short‐circuiting, fire, or even explosion. Graphene oxide (GO) in large areas has been prepared as the Li metal host via a continuous centrifugal casting method. Aligned microchannels are then fabricated in it by a simple punching method using 3D printed templates. The GO matrix effectively regulates the lithium plating/stripping behavior while the aligned channels uniformly distributes the Li‐ion flux and provides short Li‐ion diffusion paths. The Li/ holey GO composite is flexible with a controllable thickness from 50 to 150 µm, which corresponds to capacities from 9.881 to 27.601 mAh cm−2. As a result, the anode has a low overpotential of 30 mV after 100 h, a high capacity of ≈3538 mAh g−1 (91.4% of the theoretical capacity), and a superior rate ability of up to 50 C with a LiFePO4 cathode. The holey GO/Li electrode is also paired with other cathodes and used in pouch cells, indicating its suitability for various high‐energy battery systems.

Diluted High‐Concentration Electrolyte Based on Phosphate for High‐Performance Lithium‐Metal Batteries

AbstractLithium (Li) metal is an ultra‐high specific capacity and low potential ‘‘holy grail’’ anode for developing high energy density rechargeable Li metal batteries (LMBs), but its practical application suffers from the low Coulombic efficiency (CE) and dendritic lithium growth due to its thermodynamic instability to organic solvents. Here, we report a new diluted high concentration electrolyte (DHCE) containing lithium bis(fluorosulfonyl)imide, triethyl phosphate and fluorobenzene cosolvent, which not only guarantees lithium metal anode (LMA) with an 98.4 % high average CE over 250 cycles but greatly improves Li||NMC622 cells property (70 % capacity retention after 200 cycles at C/3 current density). Therefore, this new electrolyte can provide more possibilities for developing high‐energy‐density LMBs.

Self-assembled, highly-lithiophilic and well-aligned biomass engineered MXene paper enables dendrite-free lithium metal anode in carbonate-based electrolyte

Lithium metal anode is the ideal candidate for high-energy–density rechargeable batteries. However, uncontrolled dendrite growth hampers its commercialization. Herein, a dendrite-free composite Li metal anode is realized by a flexible, freestanding, well-aligned and highly-lithiophilic MXene paper designed by a facile electrostatic self-assembly of the exfoliated MXene nanosheets and natural polysaccharide-chitosan (MX@CS). The MX@CS paper gets a well-aligned layered-3D structure with a micro-crumpled surface that can effectively decrease the local current density, guide even Li plating and suppress dendritic Li growth. More importantly, surface-adsorbed chitosan endows enhanced lithiophilicity for MXene substrate and thus reduces the Li nucleation overpotential, which is confirmed by the density functional theory calculations. Abundant lithiophilic groups on MX@CS surface provide high-concentration Li+ anchoring site promoting Li nucleation and laterally inducing uniform Li deposition, which effectively avoids the formation of dendritic Li. As a result, the MX@CS-Li anode with a dendrite-free Li morphology shows a significantly improved cycling life in commercial carbonate-based electrolyte. When coupled with LiNi0.8Co0.1Mn0.1O2 cathode, the full cell exhibits a low capacity decay and steady ultrahigh Coulombic efficiency of 99.6% at a current density of 5C. These findings develop a new approach for designing high-performance metal-based rechargeable batteries.

Homogenizing the Li-ion flux by multi-element alloying modified for 3D dendrite-free lithium anode

Metallic Li anode has attracted much attention for the high energy density rechargeable Li batteries, owing to the low potential and ultrahigh theoretical specific capacity. However, the Li dendrite growth and high activity of Li hinder the application of lithium anode. In this work, the multiplex alloy composite skeletons have been prepared via a facile two-step preparation method to solve the drawbacks of Li anode, which can form uniformly distributed nucleation sites, homogenize Li-ion flux and reduce local ionization density to suppress the growth of lithium dendrites. Based on the analysis of cross-sectional operando microscopy images, it can be confirmed that the synthesized 3D composite alloy anodes can effectively suppress the formation and growth of lithium dendrites. Li-Mg-Ca electrode exhibits the most excellent mechanical property, thermostability, interfacial stability and electrochemical cycling stability. Specifically, Li-Mg-Ca alloy electrode exhibits the stable charge-discharge cycling performance for 1000 h (pristine Li only for 120 h) at a current density of 2 mA cm−2 for 4 mAh cm−2. The practical 350 Wh kg−1 pouch cell works well and meets the energy requirements of electronic devices. Importantly, the research work in this article provides research ideas for the later lithium-free anode materials.