High Reversible Capacity Research Articles

Highly crosslinked resin prepares hard carbon anode for enhanced sodium storage performance and reduced cost

Resins have shown significant potential as a precursor for hard carbons (HCs) in sodium-ion batteries (SIBs) due to their high purity and adjustability. However, the high cost and low Na+ storage capacity limit their industrialization. Herein, the highly crosslinked resin is developed by linear phenolic resin crosslinking with inexpensive hexamethylenetetramine (HMTA) via the C-N and methylene bridges between phenolic rings, which can effectively reduce the resin consumption ratio by over 44% per unit mass and regulate the sodium storage performance of the prepared HC with a high reversible capacity of 323.9 mAh g-1 and an initial coulombic efficiency (ICE) of 90.7% at 15 mA g−1, where a high plateau capacity of 286.8 mAh g-1 is proved to be a coupled storage mechanism of intercalation and pore-filling behavior. Meanwhile, defects associated with hydrogen content, rather than nitrogen defects, are verified to be directly linked to slope capacity. Furthermore, the 18650 cylindrical-type batteries assembled with this HC anode coupled with NaFe1/3Ni1/3Mn1/3O2 cathode achieve a high energy density of about 280.9 Wh kg−1 and excellent capacity retention of 86.4% over 2500 cycles, providing a promising prospect for the practical application of the resin-based HC for SIBs.

A Recyclable Polyimide Derived Hard Carbon as a High‐Performance Negative Electrode Material for Sodium‐Ion Batteries

AbstractHard carbon, characterized by high ion storage capacity, low operating voltage, and excellent cycling stability, is considered an ideal negative electrode material for sodium‐ion batteries. However, the high cost and low carbon yield of thermosetting precursors limit their practical application in SIBs, while low‐cost and high‐yield raw materials exhibit highly ordered carbon structures and narrow interlayer spacing under high‐temperature carbonization. Discarded polyimide materials are inexpensive, which offer a high carbon yield and possess good thermal stability and thermoplasticity, with functional groups of imide rings (−CO−N−CO−) on their main chains. This study recycled and converted polyimide materials into hard carbon materials from discarded engineering plastics, investigating the influence of carbonization temperature on the degree of graphitization, interlayer spacing, and pore structure of the materials to achieve high reversible sodium storage capacity. After carbonization at 1300 °C, the polyimide material exhibited 319 mAh g−1 reversible capacity and excellent electrochemical performance (with a capacity retention of 91.92 % after 100 cycles at a 0.5 C current rate) and rate performance (up to 242.5 mAh g−1 at 2 C). This study provided a simple, high‐yield, and effective method for the reuse of discarded organic polymers, promoting the sustainable utilization of resources.

One-step oil bath preparation of cobalt-doped MnO2/coconut activated carbon composite with superior zinc ion storage performance

MnO2 is a prospective cathode material for aqueous zinc ion batteries due to its high theoretical capacity and low cost. However, bare MnO2 usually suffers from large volume change and dissolution problems. In this work, Co-doped MnO2/coconut activated carbon composite (Co-β-MO/CAC) has been successfully synthesized by a one-step oil bath method. The electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) tests demonstrate that both the Co doping and the incorporation of coconut activated carbon can effectively reduce the electrochemical reaction resistance of MnO2 and improve the intercalation and deintercalation abilities of H+ and Zn2+. The combined effect of the Co doping and CAC compositing has resulted in excellent electrochemical property of Co-β-MO/CAC. After 120 cycles at 0.2 A g−1, the capacity of Co-β-MO/CAC increases from 224.7 mAh g−1 to 436.7 mAh g−1. Moreover, the composite can also deliver a high reversible capacity of 233.2 mAh g−1 after 900 cycles at 0.5 A g−1.

Copper-doping enhanced electrochemical performance of cobalt embedded nitrogen-doped porous carbon dodecahedra in lithium-ion half/full batteries

The creation of negative electrode materials that have quick redox kinetics, reduced volumetric expansion, and a high reversible specific capacity is the linchpin to the advancement of lithium-ion batteries. Here, we prepared copper-doping cobalt-embedded nitrogen-doped porous carbon (CoCu@NC) by calcining copper-modified ZIF-67. The unique hollow structure presents a fast ionic diffusion channel and good structural stability. Density functional theory (DFT) calculation testifies that Cu-doping can regulate the electronic structure of the CoCu@NC surface as well as enhance lithium ions adsorption capacity on nitrogen sites. Furthermore, the presence of N and Cu could generate more defects, thereby achieving rapid storage reaction kinetics of lithium ions. Benefiting from the cooperative effect between Co and Cu double-doped at NC, strain and stress are alleviated during lithium-ion intercalation/deintercalation processes, thus improving cycling stability and performance. Therefore, CoCu@NC shows a superior capacity of 1155.10 mAh g−1 at a current density of 0.5 A g−1, and good stability with 310.90 mAh g−1 at 10 A g−1 after 600 cycles. The assembled LiCoO2//CoCu@NC-7 lithium-ion full battery can achieve a discharge-specific capacity at 3 A g−1 for 182.60 mAh g−1 after 500 cycles.

One-step surface-to-bulk modification of single-crystalline Ni-rich Co-poor cathodes for high-rate and long-life Li-ion batteries at high-voltage operations

Single-crystalline Ni-rich Co-poor cathodes operating at high-voltage are attractive owing to their higher energy density for meeting the requirements of next-generation Li-ion batteries, yet they usually suffer from sluggish Li-ion diffusion kinetics and serious Li/Ni disordering. Herein, an in-situ co-precipitation strategy is implemented to achieve the novel In-doped and Li3InO3 coated single-crystalline LiNi0.90Co0.05Mn0.05O2 cathodes with a highly ordered layered structure. The In-doping facilitates grain growth by decreasing the surface energy of crystal faces, reducing the synthesis temperature by about 20 °C, which thus drastically suppresses Li/Ni disordering and lattice oxygen loss. Furthermore, the pillar effect of In-ion doping and the in-situ formation of the ultrafast Li-ion conductive Li3InO3 coating synergistically enhance the Li-ion diffusion kinetics. These merits enable the as-obtained Ni-rich Co-poor cathodes with a high reversible capacity of 229.4 mAh g−1 at 0.1C and 124.6 mAh g−1 at 7C. In a pouch-type full cell, 93.9 % of the initial capacity is still maintained after 500 cycles at 1C within 2.7–4.5 V. This finding opens up a new path for improving the rate performance and cycle life of single-crystalline Ni-rich cathodes for high-voltage Li-ion batteries.

Surface Reconstruction of High-Voltage LiNi0.5Mn1.5O4 Cathode via the Sculpture Method toward Enhanced Stability.

High-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes suffer from severe capacity degradation during long-term cycling due the manganese dissolution and their high operating voltage (∼4.95 V), which pose serious challenges at the surface or interface. Moreover, both traditional ion-doping and passivation layer coating are difficult to apply consistently to LNMO cathode because of their complicated procedures, especially in large-scale production. To address these issues, a strategy employing HNO3/H2O2 leaching in synergy with a sintering process at a mid-temperature of 700 °C was used to achieve selective surface reconstruction. An optimal ratio of reactants was applied to balance the capacity and the cyclic stability of the LNMO cathode. The optimized valence composition of Mn on the material surface mitigates the occurrence of Jahn-Teller distortion, accompanied by a reasonable ratio of ordered and disordered phases and the concentration of oxygen vacancies after sintering, which improves the interface behavior between the electrode and electrolyte. This method delivers a high reversible capacity of 116.5 mAh g-1 after 200 cycles at 0.5 C (1 C = 147 mAh g-1) with a capacity retention of 91.30% and 110 mAh g-1 with a remarkably high capacity retention of 86.85% after 500 cycles at 2 C. This balanced approach, utilizing the protective effects of oxidation (O22-) and the erosive action of acid (H+), is proposed to achieve regional surface reconstruction of advanced LNMO cathode. This opens up a strategy for improving oxide-based cathode materials with low cost and mass production capability, especially favoring high consistency.

Achieving High‐Voltage Stability in Li‐Rich Ni‐Rich Oxides with Local W/Ni(Li) Superstructure

AbstractCreating high‐energy‐density cathodes is crucial for building next‐generation lithium‐ion batteries. However, materials exploration along two main directions, namely Li‐rich or Ni‐rich oxides, has encountered bottlenecks. To get rid of the impasse, here a “Li‐rich Ni‐rich” route is consolidated by designing a new family of Li1+yNi(3‐5y)/3W2y/3O2 oxides with high‐voltage cycling stability up to 4.5 V and high capacities over 230 mAh g−1. It is discovered that W6+ is largely incorporated into the LiNiO2 lattice, forming W/Ni(Li) inverse honeycomb‐ordered nano‐domains. These Li‐rich domains enable reversible anionic redox, clearly demonstrated by X‐ray absorption spectroscopy, resonant inelastic X‐ray scattering, transmission electron microscopy, and nuclear magnetic resonance, which is linked to improved electrochemical performance. Furthermore, the incorporation of W6+ into the lattice proves to be the key to generating electrochemically active Li‐rich domains irrespective of Li stoichiometry given that a similar local structure is found in W‐substituted non‐Li‐rich oxides. This therefore implies the underestimated role of high‐valence cations in tuning the structure and electrochemistry of Ni‐rich oxides. These results underline the necessity of a Li‐rich composition in the request for reversible high capacity, reinforcing the promise of a “Li‐rich Ni‐rich” avenue for developing advanced cathodes.

Co‐Based Metal–Organic Frameworks With Dual Redox Active Centers for Lithium‐Ion Batteries With High Capacity and Excellent Rate Capability

AbstractSmall molecule organic materials are widely used as anode materials for lithium‐ion batteries (LIBs) due to their high reversible capacity, designable structure, and environmental friendliness. However, they suffer from poor intrinsic electronic conductivity, severe dissolution, and low initial coulombic efficiency. Recently, metal–organic frameworks (MOFs) have demonstrated in metal‐ion batteries, outperforming some small molecule organic materials in terms of both cycling stability and rate capability. Herein, the first rational design and synthesis of a new cobalt‐based MOF (CoBPDCA), are reported employing cobalt(II) nitrate as the metal source and small organic molecules (2,2‐bipyridyl‐4,4‐dicarboxylic acid, BPDCA) as the ligands, which shows exceptional chemical stability and impressive electron conductivity. Most importantly, CoBPDCA electrodes deliver a high reversible capacity of 1112.9 mAh g−1 at 0.05 C (1 C = 1000 mA g−1) and outstanding high‐rate durability (166.3 mAh g−1 after 2500 cycles at 10 C). Employing a series of spectroscopic and morphological characterizations and density functional theory (DFT) calculations, it is revealed that these impressively electrochemical performances are contributed to the dual active redox centers of Co cations and BPDCA ligands (CN and CO groups), and the superb electron conductivity. This work might provide a new strategy and a deeper understanding of the other MOFs' development for LIBs.

FeS2/SnS2@C with mosaic-like heterointerface as robust sodium anode

Sodium-ion batteries (SIBs) have been widely researched due to their abundant resource and inherent safety. However, the major challenge for further commercialization of SIBs is the absence of low-priced anode electrodes with high reversible capacity and durability. Herein, a hierarchical heterogeneous structure of FeS2/SnS2@C nanocubes with rich two-dimensional mosaic-like heterointerface and N/S co-doped carbon wrapping is constructed and synthesized, to achieve ultrahigh reversible capacity and long cycling stability as anode of SIBs. Combining x-ray photoelectron spectroscopy, ion diffusion kinetic analysis, and in situ x-ray diffraction, the exquisite hierarchical heterogeneous structure of FeS2/SnS2@C could promote charge/electrons transfer and accelerate ion diffusion kinetics. As expected, the FeS2/SnS2@C anode shows superior reversible capacity (867.5 mA h g−1 at 0.1 A g−1), good rate performance (718.9 mA h g−1 at 5.0 A g−1), and long cycle stability (738.0 mA h g−1 after 1200 cycles at 5.0 A g−1) with Na metal as counter electrode. This work proves that the effectiveness of heterojunction interfaces for promoting Na+ diffusion is highlighted by such capabilities.

Layered Structure Modification of Sodium Vanadate through Ca/F Co‐Doping for Enhanced Energy Storage Performance

AbstractVanadate materials are promising for sodium‐ion batteries (SIBs) due to their low cost, high capacity, and high power characteristics enabled by vanadium's multiple oxidation states. However, their development is hindered by poor conductivity, suboptimal high‐rate performance, and limited cycle life. In this work, a layered structure modification strategy involving Ca/F co‐doping in sodium vanadate Na2CaV2O6F (CVF) is proposed to address these issues. Through a combination of experiments and density functional theory calculations, it is demonstrated that Ca/F synergies enhance the Na layer spacing in CVF, resulting in reduced crystal water content and volume shrinkage compared to Na2V2O6 (NVO). Additionally, Ca/F incorporation significantly mitigates the diffusion potential of Na+ within the material framework. The unmodified CVF sample exhibits a high reversible capacity of 220 mAh g−1 at 10 mA g−1 and an excellent rate capacity of 65.78 mAh g−1 at 400 mA g−1. Furthermore, the cathode material maintains a capacity of up to 138 mAh g−1 at 200 mA g−1 and retains 104.88 mAh g−1 after 100 cycles within the voltage range of 1.5−4.0 V. These findings enhance the understanding of the crystal structure of NVO cathode materials and pave the way for the rational design of high‐quality vanadate cathodes for SIBs.

Heterogeneous NASICON-Type Cathode With Reversible Multielectron Reaction for High-Performance Sodium-Ion Batteries.

Na superionic conductor (NASICON)-structured compounds demonstrate great application potential by their robust framework and compositional diversity. However, they are blamed for the mediocre energy density, and achieving both multielectron reaction and good cycling stability simultaneously is challenging. Herein, a novel heterogeneous Na4Fe3(PO4)2(P2O7)/Na2VTi(PO4)3 (NFPP/NVTP) material with stable multielectron reaction is constructed by spray drying technology. The mutual promotion effect of intergrowth structures effectively improves the purity and the crystallization of NFPP/NVTP during the fabrication process, which is beneficial to the high capacity and cycling stability. As a result, the optimized NFPP/NVTP demonstrates a high reversible capacity of 155.3 mAh g-1 at 20mA g-1 and outstanding cycling stability with 82.9% capacity retention over 2500 cycles at 1 A g-1, which are much superior to those of NFPP and NVTP individually. Even in full cell configuration, the energy density remains high at ≈380Wh kg-1 based on the cathode mass. The high capacity of NFPP/NVTP is also attributed to the successive reduction/oxidation mechanism involving the introduction of Ti3+ and interfacial charge redistribution effect between the heterogeneous phases, which greatly improve the electronic and ionic conductivity. Moreover, high reversible structural evolution during the multisodium storage process further guarantees excellent cycling stability.

Interfacial Sb[sbnd]O[sbnd]C bond and structural confinement synergistically boosting the reaction kinetics and reversibility of Sb2Se3/NC nanorods anode for sodium storage

Antimony selenide (Sb2Se3) has been considered as a prospective material for sodium-ion batteries (SIBs) because of its large theoretical capacity. Whereas, grievous volume expansion caused by the conversion-alloying reaction leads to fast capacity decay and inferior cycle stability. Herein, the confined Sb2Se3 nanorods in nitrogen-doped carbon (Sb2Se3/NC) with interfacial chemical bond is designed to further enhance sodium storage properties of Sb2Se3. The robust enhancing effect of interfacial SbOC bonds can significantly promote electron transfer, Na+ ions diffusion kinetics and alloying reaction reversibility, combining the synergistic effect of the unique confinement structure of N-doped carbon shells can efficiently alleviate the volume change to ensure the structural integrity. Moreover, in-situ X-ray diffraction reveals intercalation/de-intercalation, conversion/reversed conversion reaction and alloying/de-alloying reaction mechanisms, and the kinetics analysis demonstrates the diffusion-controlled to contribute high capacity. As a result, Sb2Se3/NC anode delivers a high reversible capacity of 612.6 mAh/g at 0.1 A/g with a retentive specific capacity of 471.4 mAh/g after 1000 cycles, and long-cycle durability of over 2000 cycle with the reversible capacities of 371.1 and 297.3 mAh/g at 1 and 2 A/g are achieved, respectively, and an good rate capability. This distinctive interfacial chemical bonds and confinement effect design shows potential applications in the improved conversion/alloying-type materials for SIBs.

Synthesis of a MOF derived porous graphene and pyrolytic carbon supported zinc stannate nanohybrid electrode with enhanced lithium-ion storage performances

Compositing nano-sized zinc stannate (Zn2SnO4) with supportive carbon skeleton usually brings in improved lithium-ion storage performances. One of the most challenging tasks is to effectively stabilize Zn2SnO4 nanocrystals via simplified preparation routes from eco-friendly raw materials. In this work, the water-soluble natural molecule gallic acid (GA) is directly employed to coordinate with Zn2+/Sn2+ ions, and the corresponding metal-organic framework (MOF) precursor samples of pure Zn-GA MOF and bimetallic ZnSn-GA MOF can be synthesized. The Zn-GA MOF and ZnSn-GA MOF precursors are further converted to a three-dimensional (3D) porous graphene sample (ZMG) and a pyrolytic carbon domain supported Zn2SnO4 nanocomposite (Zn2SnO4@C), respectively, by taking the advantages of the unique micro-structures and compositions of MOF materials. By rationally mixing the ZMG and Zn2SnO4@C in electrode fabrication, the finally obtained Zn2SnO4@C/ZMG nanohybrid electrode exhibits a high reversible capacity of 1117 mAh·g−1 after 500 cycles at a current density of 1000 mA g−1 in half-cells as well as inspiring full-cell performance. The favorable synergistic effect in lithium-ion storage for the Zn2SnO4@C/ZMG electrode has been investigated. The MOF derived samples and involved sustainable synthesis protocols can be further developed for wider applications.

Extremely Durable K-Ion Batteries Enabled by Heteroatom Co-Doped Highly-Ordered Porous Carbon Spheres with Nearly 100% Capacity Retention up to 11,000 Cycles.

Currently, one major target for exploring K-ion batteries (KIBs) is enhancing their cycle stability due to the intrinsically sluggish kinetics of large-radius K+ ions. Herein, we report a rationally designed electrode, the S/O co-doped hard carbon spheres with highly ordered porous characteristics (SPC), for extremely durable KIBs. Experimental results and theory calculations confirm that this structure offers exceptional advantages for high-performance KIBs, facilitating rapid K+ diffusion and (de)-intercalation, efficient electrolyte penetration and transport, improved K+ storage sites, and enhanced redox reaction kinetics, thus ensuring the long-term cycle stability. As a result, the as-constructed SPC anode delivers a high reversible capacity of ca. 200 mAh g-1 at a high current density of 2.0 A g-1 and robust stability with ∼100% capacity retention up to 11,000 cycles, outperforming most carbon-based KIB anodes. This work offers insight into developing advanced KIBs with durable stability toward practical applications.

Novel metal-organic anode material by in-situ chelating Ni2+ with tannic acid on carbon nanotube for high-performance Li storage

Lithium-ion batteries (LIBs) with natural organic anode are attracting intensive interest for application owing to their structural diversity, cost-effectiveness, eco-friendliness, and high specific capacity. However, directly usage of natural organic materials as anode materials usually encounters poor electrochemical properties such as low reversible capacity and short cycling life. Thus, developing high-performance organic electrode materials for LIBs remains a great challenge. Herein, we present a rational design and fabrication of TA-Ni@CNTs by in-situ coating TA-Ni polymers onto the surface of carbon nanotubes (CNTs) as a superior anode material for LIBs. Specifically, the highly conductive CNTs can effectively relieve the aggregation of TA-Ni and improve the electronic conductivity. Meanwhile, the strong chelation among nickel irons and catechol groups enhances the structure stability and inhibits the dissolving property. Consequently, as an anode material for LIBs, the resulting TA-Ni@CNTs achieves a high reversible capacity of 1418.8 mAh·g−1 at 0.1 A·g−1 after 216 cycles and an outstanding cycling stability with 951.1 mAh·g−1 at 0.5 A·g−1 after 323 cycles. The presented design strategy holds great promise for developing more-efficient electrode materials for LIBs.

Nickle-doped covalent organic frameworks/carbon nanotubes composite for high-performance lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are considered as one of the most promising next-generation energy storage systems. To mitigate the shuttle effect of lithium polysulfides (LiPSs) in LSBs, the rational design of sulfur hosts with high physical confinement and catalytic activity is critical to enhance the performance of LSBs. Here, we successfully prepare a nickle-doped covalent organic frameworks/carbon nanotubes composite (Ni/COFs/CNTs) as the sulfur host in LSBs. COFs can confine and immobilize sulfur species. Moreover, CNTs and Ni nanoparticles can provide fastelectrontransferpathways. Thus, Ni/COFs/CNTs composite can alleviate the shuttle effect during the cycling processes.The S/Ni/COFs/CNTs cathode displays a high initial reversible capacity of 1068.6 mAh g−1 and a high capacity retention (83.3 %) after 100 cycles at 0.1C. This work provides a useful strategy to the rational design of sulfur hosts for LSBs.

Dislocation Effect Boosting the Electrochemical Properties of Prussian Blue Analogues for 2.6 V High-Voltage Aqueous Zinc-Based Batteries.

Prussian blue analogues (PBAs) have attracted increasing attention in aqueous zinc-based batteries (AZBs) with the advantages of an open framework, adjustable redox potential, and easy synthesis. However, they exhibited a low specific capacity and a poor cycle performance. In this work, crystalline potassium iron hexacyanoferrate (FeHCF) with dislocation was designed and prepared by a poly(vinylpyrrolidone) (PVP) additive. The metastable state provided by PVP would cause an electrostatic interaction between cyanogen and water molecules. The reduced force increases the steric resistance of the water molecules entering the crystal. The low content of crystal water in FeHCF is associated with the formation of dislocation. The dislocation effect effectively improves the electrochemical reactivity and reaction kinetics of FeHCF. Thus, it presents a high reversible capacity of 131 mAh g-1 with a superior capacity retention of 85% after 550 cycles at 0.5 A g-1. When used as a cathode, the AZBs display a high voltage of 2.6 V, a fast charging capability (<5 min), and a satisfactory cycle stability with a capacity retention of 82% after 400 cycles at 0.2 A g-1 in decoupling electrolytes. This work provides an effective strategy for the design of high-performance PBA-based cathodes for 2.6 V AZBs.

Integrated Structural Modulation Inducing Fast Charge Transfer in Aqueous Zinc-Ion Batteries.

Aqueous Zn-ion batteries (AZIBs) are promising energy-storage devices owing to their exceptional safety, long cycle life, simple production, and high storage capacity. Manganese oxides are considered potential cathode materials for AZIBs, primarily because of their safety, low cost, simple synthesis, and high storage capacity. However, MnO2-based cathodes tend to deteriorate structurally during long-term cycling, which reduces their reversible capacity. In this study, an advanced α-MnO2@SnO2 nanocomposite via facile hydrothermal synthesis is developed. The synergistic effects of lattice disorder and increased electron conductivity in the α-MnO2@SnO2 nanocomposite mitigate structural degradation and enhance the overall electrochemical performance. The nanocomposite exhibits a high reversible capacity of 347 mAh g-1 at a current density of 100mA g-1 after 50 cycles. Furthermore, it exhibits excellent rate performance and stable capacity even after 1000 cycles, maintaining a capacity of 78 mAh g-1 at a high current density of 5 A g-1. This excellent electrochemical performance is attributed to the reversible Zn intercalation in α-MnO2@SnO2 nanocomposites due to the increased structural stability and fast ion/electron exchange caused by the distortion of the tunnel structure, on the basis of various ex situ experiments, density functional theory calculations, and electrochemical characterizations.

Robust Nitrogen/Sulfur Co‐Doped Carbon Frameworks as Multifunctional Coating Layer on Si Anodes Toward Superior Lithium Storage

AbstractSilicon (Si)‐based anodes hold great potential for next‐generation lithium‐ion batteries (LIBs) due to their exceptional theoretical capacity. However, their practical application is hindered by the notably substantial volume expansion and unstable electrode/electrolyte interfaces during cycling, leading to rapid capacity degradation. To address these challenges, we have engineered a porous nitrogen/sulfur co‐doped carbon layer (CBPOD) to uniformly encapsulate Si, providing a multifunctional protective coating. This innovative design effectively passivates the electrode/electrolyte interface and mitigates the volumetric expansion of Si. The N/S co‐doping framework significantly enhances electronic and ionic conductivity. Furthermore, the carbonization process augments the elastic modulus of CBPOD and reconstructs the Si‐CBPOD interface, facilitating the formation of robust chemical bonds. These features collectively contribute to the high performance of the Si‐CBPOD anodes, which demonstrate a high reversible capacity of 1110.8 mAh g−1 after 1000 cycles at 4 A g−1 and an energy density of 574 Wh kg−1 with a capacity retention of over 75.6% after 300 cycles at 0.2 C. This study underscores the substantial potential of the CBPOD protective layer in enhancing the performance of Si anodes, providing a pathway for the development of composite materials with superior volumetric energy density and prolonged cyclic stability, thereby advancing high‐performance LIBs.

An Utrastable Mg/Zr Modified P2‐Type Na2/3Ni1/3Mn2/3O2 Cathode Material for High‐Power Sodium‐Ion Batteries

AbstractP2‐Na2/3Ni1/3Mn2/3O2 demonstrates high energy density owing to its high specific capacity and high discharge voltage, but suffering from rapid performance decay due to severe structural degradation and aggravated surface side reaction during high‐voltage cycling. Herein, a Mg/Zr modified Na0.67Ni0.25Mg0.08Mn0.64Zr0.03O2 cathode is proposed with good structural stability and excellent cycling performance, showing reversible capacity of 123.2 mAh g−1 (0.1 C) and capacity retention of 99.1% after 100 cycles. The cycling stability is outstanding among P2‐type cathodes reported so far. In situ XRD analyses reveal a suppressed P2‐O2 phase transition after Mg modification, further incorporation of Zr greatly stabilizes the layered structure as some Zr ions reside in the Na layer providing a pinning effect to reduce the slide of TMO2 layer. First‐principles calculations suggest that oxygen loss in Na0.67Ni0.25Mg0.08Mn0.64Zr0.03O2 cathode is suppressed as Zr incorporation prevents the formation of oxygen vacancies. XPS analyses verify a Zr─O protective layer self‐segregated on particle surface during material synthesis. The expanded Na+ transport channel confirmed by the XRD analysis well explains the favored Na‐ion mobility verified by a high reversible capacity of 105.5 mAh/g at 20 C. This work sheds new light on providing a practical P2‐structured cathode material for high‐power sodium ion batteries.