Full-cell Battery Research Articles

Glyoxylic‐Acetal‐Based Gel‐Polymer Electrolytes for Lithium‐Ion Batteries

AbstractThis work focuses on the combination of two strategies to improve the safety of lithium‐ion batteries: The use of a glyoxylic‐acetal, 1,1,2,2‐tetraethoxyethane, in the solvent blend to reduce the flammability of the liquid electrolyte and further its confinement inside of a methacrylate‐based polymer matrix, to prevent electrolyte leakage from the battery cells. Physicochemical characterizations of this novel gel‐polymer electrolyte (GPE) confirm its improved thermal properties and suitable ionic conductivity, as well as electrochemical stability window. Tests in LFP and hard carbon half‐cells vs. lithium metal show that the combination of glyoxylic‐acetal‐based electrolyte and the methacrylate‐based polymer matrix can promote lithium‐ion intercalation and deintercalation with stable capacity values. The application in lithium‐ion battery full cells furthermore shows that the GPE can promote a similar performance compared to the respective liquid electrolyte and can therefore make possible the realization of energy storage devices with improved safety characteristics.

A three-in-one strategy of high-entropy, single-crystal, and biphasic approaches to design O3-type layered cathodes for sodium-ion batteries

O3-type layered oxides are promising cathodes for sodium-ion batteries (SIBs). However, severe volume changes, irreversible phase transitions, and sluggish Na+ ion transport kinetics lead to structural collapse and severe capacity loss. Herein, a three-in-one strategy “high entropy, single crystal, and biphase” is proposed to design O3-type layered cathodes for SIBs, which achieves enhanced structural stability and Na+ transport kinetics by the combination effect of multimetal high-entropy, the single crystal, and Li substitution. The as-prepared high-entropy oxide (HEO) cathode, Na(Fe1/6Co1/6Ni1/6Mn1/6Ti1/6)Li1/6O2, exhibits a high reversible capacity of 140.3 mAh g−1, robust cycling stability, exceptional rate capability (86 mAh g−1 at rates of 15C), excellent air-stability, and water-resistance ability. In situ X-ray diffraction reveals that the HEO cathode has highly reversible phase transitions and small volume change (ΔV=3.28 %). Ex situ X-ray absorption spectroscopy reveals that reversible Ni2+/Ni4+, Fe3+/Fe3.6+, and Co3+/Co3.6+ redox couples provide charge compensation for the high-entropy cathode at 2.0∼4.2 V. Notably, the full-cell battery based on the high-entropy cathode and hard carbon anode delivers a specific capacity of 134.3 mAh g−1 and an energy density of 390.8 Wh kg−1. This work provides valuable insights into the design of novel high-performance high-entropy cathodes for SIBs, highlighting a promising avenue for advancing rechargeable battery technology.

Charging dependent electro-chemo-mechanical coupling behavior of polymer electrolytes containing immobilized anions

Theoretical models have been developed to explore the electrodeposition stability between Li metal and salt-doped polymer electrolytes. However, there is still limited investigation on the coupling behavior between mechanics and electrochemistry in those novel nano-structured polymers with immobilized anions. In this work, we employ a multiphysics modeling framework to predict the electro-chemo-mechanical behavior of polymer electrolytes containing immobilized anions. We analyze the impacts of charging conditions, stress coupling and the immobilization of anions on their ion transport, electrical and mechanical properties during charging. Strengthening stress coupling is demonstrated to improve the diffusion-driven stability of electrodeposition, by enhancing limiting applied current densities. Compared with stress coupling, immobilizing anions surprisingly sustains the non-zero interfacial Li+-ion concentrations even at high applied currents, thereby mitigating the potential diffusion-driven instability of electrodeposition. Both stress/strain and overpotentials also get reduces with increasing the concentrations of immobilized anions. This theoretical work provides insights into the strategy of redesigning polymer electrolytes, and also lays foundation for the multiphysics modeling of electrodes and full-cell battery systems.

Air-Stable High-Entropy Layered Oxide Cathode with Enhanced Cycling Stability for Sodium-Ion Batteries.

O3-type layered oxides have been extensively studied as cathode materials for sodium-ion batteries due to their high reversible capacity and high initial sodium content, but they suffer from complex phase transitions and an unstable structure during sodium intercalation/deintercalation. Herein, we synthesize a high-entropy O3-type layered transition metal oxide, NaNi0.3Cu0.05Fe0.1Mn0.3Mg0.05Ti0.2O2 (NCFMMT), by simultaneously doping Cu, Mg, and Ti into its transition metal layers, which greatly increase structural entropy, thereby reducing formation energy and enhancing structural stability. The high-entropy NCFMMT cathode exhibits significantly improved cycling stability (capacity retention of 81.4% at 1C after 250 cycles and 86.8% at 5C after 500 cycles) compared to pristine NaNi0.3Fe0.4Mn0.3O2 (71% after 100 cycles at 1C), as well as remarkable air stability. Finally, the NCFMMT//hard carbon full-cell batteries deliver a high initial capacity of 103 mAh g-1 at 1C, with 83.8 mAh g-1 maintained after 300 cycles (capacity retention of 81.4%).

Deciphering the degradation mechanisms of nano-Si and micro-SiO anodes in lithium-ion battery full-cells using distribution relaxation times analysis

Silicon (Si) and silicon monoxide (SiO) have attracted great interest as next-generation anode materials for lithium-ion batteries (LiBs) due to their high energy density. However, their commercialization has been hindered by rapid capacity fading, which stems from mechanical degradation (e.g., cracking and delamination) and the aggressive formation of solid electrolyte interphase (SEI) layer. While understanding these degradation mechanisms in batteries necessitates in-operando measurement techniques, very few non-destructive analytical methods have been documented in literature. This paper highlights the effectiveness of combined electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) techniques in performing systematic characterization of LiNi0.6Mn0.2Co0.2O2 (NMC)/nano-Si and NMC/micro-SiO full-cells. The systematic design of experiments enabled the separate deconvolution of anode and cathode aging using symmetrical cells. This approach offered a clear understanding of the overall degradation mechanisms in the full-cells. The major impedance sources in the NMC/nano-Si full-cell were anode contact impedance, resulting from mechanical degradation of Si, and cathode charge transfer impedance, due to significant lithium loss and consequently deeper extraction of lithium ions in NMC. In contrast, micro-SiO anodes exhibited less electrode-level degradation, as evidenced by SEM images and relatively stable impedance behaviors during extended cycling, which strongly corroborate its superior capacity retention (66 % at 300th cycle) compared to that of nano-Si anode in full-cells (26.5 % at 300th cycle).

High-performance lithium-ion full-cell batteries based on transition metal oxides: Towards energy density of ∼ 1300 Wh kg−1

Half-cell structure including sufficient lithium ions for theoretical studies exhibits different electrochemical performance with commercial full-cell rechargeable lithium ion batteries (LIBs) featuring moderate lithium ions. So, understanding the property correlation between half-cell and full-cell LIBs is imperative, but remains a big challenge. Herein, a series of full-cells are assembled with transition metal oxide (TMO) nanowires as cathodes and silicon/graphite (Si/G) anode via electrochemical pre-lithiation, to figure out the key determinants in comparison to their corresponding half-cells. It is found that eletrochemical performances of half-cell and full-cell batteries are basically consistent by using insertion-type cathodes of V2O5, MoO3 and MnO2, but different in the cases of conversion-type cathodes of Fe2O3 and Co3O4 due to their high polarization relieved crystal fragmentation. In addition, compared with the other five materials, V2O5 nanowire exhibits the lowest charge transfer resistance (240.2 Ω), highest lithium ion diffusion rate (10-13 ∼ 10-11 cm2 s−1) and discharge midpoint voltage (1.6 V). Thus, V2O5||PL-Si/G achieves the state-of-the-art gravimetric energy density, discharge midpoint voltage and cycle performance, giving rise to the record-high 1288 Wh kg−1 at 0.1 A g-1 in potential range of 0.3 ∼ 4.0 V. These results indicate the significance of rational material selection and effective pre-lithiation for developing high-performance full-cell LIBs.

Achieving Planar Zn Electroplating in Aqueous Zinc Batteries with Cathode-Compatible Current Densities by Cycling under Pressure.

The value of aqueous zinc-ion rechargeable batteries is held back by the degradation of the Zn metal anode with repeated cycling. While raising the operating current density is shown to alleviate this anode degradation, such high cycling rates are not compatible with full cells, as they cause Zn-host cathodes to undergo capacity decay. A simple approach that improves anode performance while using more modest cathode-compatible current densities is required. This work reports reversible planar Zn deposition under cathode-compatible current densities can instead be achieved by applying external pressure to the cell. Employing multiscale characterization, this work illustrates how cycling under pressure results in denser and more uniform Zn deposition, analogous to that achieved under high cycling rates, even at low areal current densities of 1 to 10mAcm-2. Microstructural mechanical measurements reveal that Zn structures plated under lower current densities are particularly susceptible to pressure-induced compression. The ability to achieve planar Zn plating at cathode-compatible current densities holds significant promise for enabling high-capacity Zn-ion battery full cells.

Mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT cathode for sodium-ion batteries: Electrochemical diffusion kinetics and distribution of relaxation time analysis at different temperatures

We report the electrochemical sodium-ion kinetics and distribution of relaxation time (DRT) analysis of a newly designed mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT composite as a cathode. The specific capacity of 104 mAhg−1 is observed at 0.1 C with the average working voltage of ∼3 V. Intriguingly, a remarkable rate capability and reversibility are demonstrated up to very high current rate of 25 C. The long cycling test up to 10 C shows high capacity retention even after 2000 cycles. The detailed analysis of galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) data reveal the diffusion coefficient of 10−8–10−11 cm2s−1. We find excellent stability in the thermal testing between 25–55 °C temperatures and 80% capacity retention up to 100 cycles at 5 C. Further, we analyze the individual electrochemical processes in the time domain using the novel DRT technique at different temperatures. The ex-situ investigation shows the stable and reversible structure, morphology and electronic states of the long cycled cathode material. More importantly, we demonstrate relatively high specific energy of ≈155 Wh kg−1 (considering the total active material loading of both the electrodes) at 0.2 C for full cell battery having excellent rate capability up to 10 C and long cyclic stability at 1 C.

Near-strain-free anode architecture enabled by interfacial diffusion creep for initial-anode-free quasi-solid-state batteries

Anode-free (or lithium-metal-free) batteries with garnet-type solid-state electrolytes are considered a promising path in the development of safe and high-energy-density batteries. However, their practical implementation has been hindered by the internal strain that arises from the repeated plating and stripping of lithium metal at the interlayer between the solid electrolyte and negative electrode. Herein, we utilize the titanium nitrate nanotube architecture and a silver-carbon interlayer to mitigate the anisotropic stress caused by the recurring formation of lithium deposition layers during the cycling process. The mixed ionic-electronic conducting nature of the titanium nitrate nanotubes effectively accommodates the entry of reduced Li into its free volume space via interfacial diffusion creep, achieving near-strain-free operation with nearly tenfold volume suppressing capability compared to a conventional Cu anode counterpart during the lithiation process. Notably, the fabricated Li6.4La3Zr1.7Ta0.3O12 (LLZTO)-based initial-anode-free quasi-solid-state battery full cell, coupled with an ionic liquid catholyte infused high voltage LiNi0.33Co0.33Mn0.33O2-based cathode with an areal capacity of 3.2 mA cm−2, exhibits remarkable room temperature (25 °C) cyclability of over 600 cycles at 1 mA cm−2 with an average coulombic efficiency of 99.8%.

Enhanced electrochemical performance of cobalt-doped FeOF@activated carbon sponge for high-performance sodium-ion cathode

In this work, Co2+-doped FeOF is successfully synthesized and integrated with activated carbon sponge (ACS) to serve as a cathode for sodium-ion batteries. Doping aliovalent Co2+ enhances the ionic conductivity of FeOF by creating oxygen defects in the crystal structure of FeOF. Furthermore, the combined effects of ACS and Co2+ synergistically improve the electrical conductivity of FeOF. This feature results in an impressive discharge capacity of 465 mAh g−1 with a fading rate of 0.18 % per cycle after 100 cycles at 100 mAh g−1 in the voltage range of 1.2–4.0 V. A full-cell battery is also assembled with an ACS anode and exhibits a high energy density of 633 Wh kg−1cathode with a fading rate of 0.97 % per cycle. The mechanistic aspects of the enhanced electrochemical performance are thoroughly investigated by several ex-situ analyses and density functional theory calculations.

Adaptive Ion Channels Formed in Ultrathin and Semicrystalline Polymer Interphases for Stable Aqueous Batteries.

Aqueous Zn batteries have recently emerged as promising candidates for large-scale energy storage, driven by the need for a safe and cost-effective technology with sufficient energy density and readily accessible electrode materials. However, the energy density and cycle life of Zn batteries have been limited by inherent chemical, morphological, and mechanical instabilities at the electrode-electrolyte interface where uncontrolled reactions occur. To suppress the uncontrolled reactions, we designed a crystalline polymer interphase for both electrodes, which simultaneously promotes electrode reversibility via fast and selective Zn transport through the adaptive formation of ion channels. The interphase comprises an ultrathin layer of crystalline poly(1H,1H,2H,2H-perfluorodecyl acrylate), synthesized and applied as a conformal coating in a single step using initiated chemical vapor deposition (iCVD). Crystallinity is optimized to improve interphase stability and Zn-ion transport. The optimized interphase enables a cycle life of 9500 for Zn symmetric cells and over 11,000 for Zn-MnO2 full-cell batteries. We further demonstrate the generalizability of this interphase design using Cu and Li as examples, improving their stability and achieving reversible cycling in both. The iCVD method and molecular design unlock the potential of highly reversible and cost-effective aqueous batteries using earth-abundant Zn anode materials, pointing to grid-scale energy storage.

Lattice Engineering on Li2CO3-Based Sacrificial Cathode Prelithiation Agent for Improving the Energy Density of Li-Ion Battery Full-Cell.

Developing sacrificial cathode prelithiation technology to compensate for active lithium loss is vital for improving the energy density of lithium-ion battery full-cells. Li2CO3 owns high theoretical specific capacity, superior air stability, but poor conductivity as an insulator, acting as a promising but challenging prelithiation agent candidate. Herein, extracting a trace amount of Co from LiCoO2 (LCO), a lattice engineering is developed through substituting Li sites with Co and inducing Li defects to obtain a composite structure consisting of (Li0.906Co0.043▫0.051)2CO2.934 and ball milled LiCoO2 (Co-Li2CO3@LCO). Notably,both the bandgap and Li─O bond strength have essentially declined in this structure. Benefiting from the synergistic effect of Li defects and bulk phase catalytic regulation of Co, the potential of Li2CO3 deep decomposition significantly decreases from typical >4.7 to ≈4.25V versus Li/Li+, presenting >600 mAh g-1 compensation capacity. Impressively, coupling 5 wt% Co-Li2CO3@LCO within NCM-811 cathode, 235Wh kg-1 pouch-type full-cell is achieved, performing 88% capacity retention after 1000 cycles.

Implanting Transition Metal into Li2 O-Based Cathode Prelithiation Agent for High-Energy-Density and Long-Life Li-Ion Batteries.

Compensating the irreversible loss of limited active lithium (Li) is essentially important for improving the energy-density and cycle-life of practical Li-ion battery full-cell, especially after employing high-capacity but low initial coulombic efficiency anode candidates. Introducing prelithiation agent can provide additional Li source for such compensation. Herein, we precisely implant trace Co (extracted from transition metal oxide) into the Li site of Li2 O, obtaining (Li0.66 Co0.11 □0.23 )2 O (CLO) cathode prelithiation agent. The synergistic formation of Li vacancies and Co-derived catalysis efficiently enhance the inherent conductivity and weaken the Li-O interaction of Li2 O, which facilitates its anionic oxidation to peroxo/superoxo species and gaseous O2 , achieving 1642.7 mAh/g~Li2O prelithiation capacity (≈980 mAh/g for prelithiation agent). Coupled 6.5 wt % CLO-based prelithiation agent with LiCoO2 cathode, substantial additional Li source stored within CLO is efficiently released to compensate the Li consumption on the SiO/C anode, achieving 270 Wh/kg pouch-type full-cell with 92 % capacity retention after 1000 cycles.

High Entropy Pr-Doped Hollow NiFeP Nanoflowers Inlaid on N-rGO for Efficient and Durable Electrodes for Lithium-Ion Batteries and Direct Borohydride Fuel Cells.

The selection and design of new electrode materials for energy conversion and storage are critical for improved performance, cost reduction, and mass manufacturing. A bifunctional anode with high catalytic activity and extended cycle stability is crucial for rechargeable lithium-ion batteries and direct borohydride fuel cells. Herein, a high entropy novel three-dimensional structured electrode with Pr-doped hollow NiFeP nanoflowers inlaid on N-rGO was prepared via a simple hydrothermal and self-assembly process. For optimization of Pr content, three (0.1, 0.5, and 0.8) different doping ratios were investigated. A lithium-ion battery assembled with NiPr0.5 FeP/N-rGO electrode achieved an outstanding specific capacity of 1.61 Ah g-1 at 0.2 A g-1 after 100 cycles with 99.3 % Coulombic efficiencies. A prolonged cycling stability of 1.02 Ah g-1 was maintained even after 1000 cycles at 0.5 A g-1 . In addition, a full cell battery with NiPr0.5 FeP/N-rGO∥LCO (Lithium cobalt oxide) delivered a promising cycling performance of 0.52 Ah g-1 after 200 cycles at 0.15 A g-1 . Subsequently, the NiPr0.5 FeP/N-rGO electrode in a direct borohydride fuel cell showed the highest peak power density of 93.70 mW cm-2 at 60 °C. Therefore, this work can be extended to develop advanced electrode for next-generation energy storage and conversion systems.

New Template Synthesis of Anomalously Large Capacity Hard Carbon for Na‐ and K‐Ion Batteries

AbstractHard carbon (HC) is a promising negative‐electrode material for Na‐ion batteries. HC electrochemically stores Na+ ions, resulting in a non‐stoichiometric chemical composition depending on their nanoscale structure, including the carbon framework, and interstitial pores. Therefore, optimizing these structures for Na storage by altering the synthesis conditions can enhance the capacity of Na‐ion batteries. In this study, HCs using MgO, ZnO, and CaCO3 as nanopore templates are systematically investigated, and the ZnO template is found to be particularly effective. By optimizing the concentration of ZnO embedded in the carbon matrix, utilizing a blend of zinc gluconate, and zinc acetate as starting materials, the optimal ZnO‐template HC demonstrates a reversible capacity of 464 mAh g−1 (corresponding to NaC4.8) with high initial coulombic efficiency of 91.7% and low average potential of 0.18 V versus Na+/Na. Thus, a Na‐ion battery full cell consisting of Na5/6Ni1/3Fe1/6Mn1/6Ti1/3O2 and the optimized ZnO‐template HC demonstrates a remarkable energy density of 312 Wh kg−1, comparable to that of a Li‐ion battery with LiFePO4 and graphite. Moreover, the ZnO‐template HC in a K half‐cell also displays a significant capacity of 381 mAh g−1, that is, KC5.8 where the alkali content is higher than stage‐1 graphite intercalation compounds, LiC6 and KC8.

Stabilizing Decavanadate Cluster as Electrode Material in Sodium and Lithium-ion Batteries.

Decavanadate ([V10 O28 ]6- , {V10 }) clusters are a potential electrode material for lithium and post-lithium batteries; however, their low stability due to the solubility in liquid organic electrolytes has been challenging. These molecular clusters are also prone to transform into solid-state oxides at a moderate temperature needed in the typical electrode fabrication process. Hence, controlling the solubility and improving the thermal stability of compounds are essential to make them more viable options for use as battery electrodes. This study shows a crystal engineering approach to stabilize the cluster with organic guanidinium (Gdm+ ) cation through the hydrogen-bonding interactions between the amino groups of the cation and the anion. The comparison of solubility and thermal stability of the Gdm{V10 } with another cluster bearing tetrabutylammonium (Tba+ ) cation reveals the better stability of cation-anion assembly in the former than the latter. As a result, the Gdm{V10 } delivers better rate capability and cycling stability than Tba{V10 } when tested as anode material in a half-cell configuration of a sodium-ion battery. Finally, the performance of the Gdm{V10 } anode is also investigated in a lithium-ion battery full cell with LiFePO4 cathode.

Zincophilic Interfacial Manipulation against Dendrite Growth and Side Reactions for Stable Zn Metal Anodes.

Constructing multifunctional interphases to suppress the rampant Zn dendrite growth and detrimental side reactions is crucial for Zn anodes. Herein, a phytic acid (PA)-ZnAl coordination compound is demonstrated as a versatile interphase layer to stabilize Zn anodes. The zincophilic PA-ZnAl layer can manipulate Zn2+ flux and promote rapid desolvation kinetics, ensuring the uniform Zn deposition with dendrite-free morphology. Moreover, the robust PA-ZnAl protective layer can effectively inhibit the hydrogen evolution reaction and formation of byproducts, further contributing to the reversible Zn plating/stripping with high Coulombic efficiency. As a result, the Zn@PA-ZnAl electrode shows a lower Zn nucleation overpotential and higher Zn2+ transference number compared with bare Zn. The Zn@PA-ZnAl symmetric cell exhibits a prolonged lifespan of 650 h tested at 5 mA cm-2 and 5 mAh cm-2 . Furthermore, the assembled Zn battery full cell based on this Zn@PA-ZnAl anode also delivers decent cycling stability even under harsh conditions.

Zincophilic Interfacial Manipulation against Dendrite Growth and Side Reactions for Stable Zn Metal Anodes

AbstractConstructing multifunctional interphases to suppress the rampant Zn dendrite growth and detrimental side reactions is crucial for Zn anodes. Herein, a phytic acid (PA)‐ZnAl coordination compound is demonstrated as a versatile interphase layer to stabilize Zn anodes. The zincophilic PA‐ZnAl layer can manipulate Zn2+ flux and promote rapid desolvation kinetics, ensuring the uniform Zn deposition with dendrite‐free morphology. Moreover, the robust PA‐ZnAl protective layer can effectively inhibit the hydrogen evolution reaction and formation of byproducts, further contributing to the reversible Zn plating/stripping with high Coulombic efficiency. As a result, the Zn@PA‐ZnAl electrode shows a lower Zn nucleation overpotential and higher Zn2+ transference number compared with bare Zn. The Zn@PA‐ZnAl symmetric cell exhibits a prolonged lifespan of 650 h tested at 5 mA cm−2 and 5 mAh cm−2. Furthermore, the assembled Zn battery full cell based on this Zn@PA‐ZnAl anode also delivers decent cycling stability even under harsh conditions.

Architecting for Mass Transport: It Is More Than Just Tortuosity

Mass transport is performance-defining across energy storage devices. An example of this limitation is evident in energy dense lithium-ion batteries (LIBs), which develop concentration gradients from insufficient transport of lithium-ions (Li-ions) when operated at high current rates. This results in lowered capacity and energy due to underutilized active material and increased overpotential. The movement of Li-ions, or lack thereof is the root cause of the trade-off that exists between energy and power density in LIBs. To alleviate societal demur towards the full adoption of electric vehicles, range anxiety and slow charging are predominant challenges that industry and academia are rushing to overcome. These goals may require reimagined processing methods to move beyond planar electrodes with disorganized and heterogeneous porosity to create architectures that are dense in active material and contain tailored porosity. To maximize the geometric component of diffusion and species flux, porous low-tortuosity channels are a rational design choice, as they act as mass-transport highways for much needed through-plane Li-ion transport.One such innovative process is hybrid inorganic phase inversion (HIPI), a manufacturing method that is scalable, material-agnostic and results in low-tortuosity free-standing and monolithic architectures with tunable material-to-pore ratios. The HIPI process can enable electrodes with adjustable thicknesses of 100s of µm and relevant micro-architectural feature sizes between 5-40 µm, tailored by tuning the gelation temperature and nucleation density of the inorganic suspension during the nonequilibrium HIPI process. Importantly, the use of a soft organogel casting support results in the unhindered accessibility of the low-tortuosity pores present in the HIPI architectures.HIPI-architected anode and cathode electrodes exhibit electrochemical and architectural stability over a 1000 cycles in a full-cell battery. Further, mass-transport constraints appear at high current densities, and we identify the lithiation step as rate-performance limiting, a result of insufficient Li-ion supply and concentration polarization. Thus, for energy and power dense LIBs the answer is not simply mass-transport highways as unoptimized low-tortuosity channels, rather in-plane Li-ion demands must be tethered to the through-plane transport. Our results demonstrate the need for and feasibility of tailored electrode architectures where dimensional ratios between low-tortuosity channels, the charge-storing matrix, and electrode thickness are tunable, to both understand multi-scale structure-performance relationships and meet coupled power and energy-storage requirements.

High-Ni NMC Cathode Material with Concentration Gradients in Lithium-Ion Batteries

Due to the high capacity and the high discharge potential, Ni-rich layered cathode materials are considered as a class of promising cathode material and attracting considerable attention. Because of the Li+/Ni2+ cation mixing, Li residues, overcharging, crystal orientation of the secondary particles, poor cycling stability and rate capability are usually received in lithium ion batteries. In this presentation, we introduce a layered NMC811 with Ni-gradients by using metal-organic framework (MOF) as precursor ( Cell Reports Physical Science , 3 (2022), 100767). The self-healing phase by forming a cation mixing layer on the surface of particles effectively improved the structural stability by suppressing the phase transition and internal cracks upon cycling. In the half-cell battery, an initial capacity of 203.5 mAh/g at 0.1 C and a capacity retention of 88.5% after 300 cycles at 1/3 C were obtained. The battery still showed a CE of 99.47% at 1/3 C after 300 cycles at 55 ℃. In addition, the full-cell battery showed a capacity retention of >86.7% with a CE of >99.86% at 1/3 C after 300 cycles. Moreover, a pouch cell delivered an initial capacity of 297.62 mAh and a CE of 99.48%, which contributed to an energy density of 216.41 Wh/kg. The capacity retention was still as high as 84.1% after 500 cycles at 1.0 C. Keywords: Li-ion batteries; Ni-rich cathode materials; MOF; Concentration gradient