HSSEs emerge as a highly promising material for next-generation all-solid-state lithium batteries. Their unique combination of high ionic conductivity, wide electrochemical window, and good mechanical properties makes them key materials for achieving high energy density and safe energy storage. Significant progress is made in understanding the classification of crystalline and amorphous halide materials, elucidating their ion transport mechanisms, and developing diverse synthesis and modification strategies to tailor their properties.

Despite this significant progress, several challenges are addressed to fully realize their potential. 1) Improving the ionic conductivity of fluoride-based electrolytes: Although fluorides offer the advantage of high-voltage stability, their ionic conductivity remains rather low. Future research must focus on overcoming this bottleneck through novel structural design, doping strategies, or the development of amorphous fluoride phases; 2) Enhancing electrochemical stability against lithium metal anodes: When halide solid-state electrolytes come into contact with lithium metal anodes, their metal cations are susceptible to reduction, leading to interfacial instability and capacity decay. Therefore, the rational design of stable artificial solid-electrolyte interphase layers that can both protect the electrolyte from reduction and ensure smooth lithium-ion transport is crucial; 3) Deepening the understanding of amorphous transport mechanisms: Although amorphous halides exhibit a superior conductivity, the fundamental principles governing ion transport in these disordered structures are not yet fully understood. Advanced characterization techniques and theoretical simulations are needed to elucidate the roles of dynamic structural relaxation and local chemical environments; and 4) Developing scalable and sustainable synthesis methods: Moving beyond laboratory-scale synthesis to develop cost-effective, environmentally friendly, and scalable production methods is key to commercialization. This includes exploring and optimizing water-based or solvent-based synthesis routes for a wider range of materials. The focused research will pave a way for the practical application of halide solid-state electrolytes. Their successful integration into all-solid-state lithium batteries holds a potential to revolutionize energy storage, providing safer, more powerful, and longer-lasting batteries for a wide range of applications, from consumer electronics to electric vehicles and grid-scale energy storage.

Conventional cement-based materials exhibit excellent compressive performance, but are inherently brittle, with inadequate tensile, flexural and deformation capacities, which readily induce cracking and impair the durability and long-term service performance of structures. At present, incorporating organic polymers or inorganic nanomaterials is proven as one of the effective strategies to enhance the mechanical properties of cement-based materials. Organic polymers are widely adopted in cement-based materials for their superior plasticity and toughness. They can adsorb onto the surface of cement particles via electrostatic interaction or hydrogen bonding, changing the hydration process of cement and optimizing the distribution and microstructure of hydration products. In addition, inorganic nanomaterials (e.g., nano-silica, carbon nanotubes and graphene oxide) can also improve the mechanical properties of cement-based materials due to their high specific surface area and reinforcement effect. However, these modification methods have some limitations. For most polymers, their effect on the flexural and compressive strengths of cement-based materials has a negative correlation, and improving the flexural strength can result in a significant reduction in the compressive strength. Furthermore, inorganic nanomaterials suffer from a poor dispersion in cement matrix, which easily causes agglomeration and uneven distribution. In addition, inorganic nanomaterials mainly improve the early compressive performance of cement-based materials, while their enhancement effect on flexural strength is relatively limited. Using organic/inorganic nanocomposites to optimize the microstructures of cement hydration products at the micro/nanometre scale is thus a promising method for improving the mechanical properties of cement-based materials. In this work, α-lipoic acid (TA), a natural bioactive molecule with a five-membered ring disulfide bond, was innovatively introduced and self-polymerized at a high temperature to prepare a dynamic polylipoic acid (PTA) network. Selective esterification modification of reactive hydroxyl groups on microcrystalline cellulose (MCC) molecular chains with PTA could improve MCC dispersibility and endow it with organic polymer characteristics. The prepared PTA-MCC hybrid material exhibited excellent mechanical enhancement in the cement matrix, which can significantly improve the flexural strength of cement-based materials at a low dosage without compromising compressive strength, thus effectively breaking through the technical bottleneck of synergistically enhancing strength and toughness of cement-based materials.

For the synthesis of polylipoic acid fiber hybrid material (MCPTS), TA powder was weighed according to a selected ratio, reacted in an oil bath at 150 ℃ for 1 h and cooled naturally to obtain linear PTA. The activated MCC and linear PTA were added to DMF solvent in a proportion, fully stirred to form a uniform system, and reacted in an oil bath at 120 ℃ for 6 h. After the reaction, the product was centrifuged and dried by rotary evaporation to obtain the final product of MCPTS. The products were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM), confirming that the activated MCC and linear PTA could be fully combined, and the target hybrid material was prepared.

The results of mechanical properties of cement paste show that the MCPTS synthesized can effectively improve the comprehensive mechanical properties of cement-based materials, especially a small increase in its compressive strength, which greatly improves the flexural strength of cement-based materials. Under the premise of ensuring that its compressive strength does not decrease, the flexural strength of cement-based materials is synergistically improved. The XRD patterns of cement-based materials at 3-d and 28-d curing ages reveal that the MCPTS-added group promotes cement hydration to a certain extent. Some cement hydration products like calcium hydroxide (CH) and calcium silicate hydrate (C-S-H) gel are formed in the system as the hydration age increases. The SEM images demonstrate that the cement paste has a much denser microstructure with a large number of clustered C-S-H hydration products after the incorporation of MCPTS. The results of cement hydration exothermic tests indicate that cement pastes with MCPTS show a significant hydration acceleration effect, with the occurrence time of their main hydration exothermic peaks advanced to varying degrees and the peak hydration rate increases remarkably.

In this paper, a type of MCPTS hybrid material with dynamic hybrid of PTA and MCC was prepared for a synergistic enhancement of organic-inorganic hybrid. It has reversible covalent bond and non-covalent bond dynamic network structure. The optimal performance was achieved at a dosage of 1.0‰ MCPTS-1. The flexural strength at 3, 7 d and 28 d was increased by 8.56%, 25.91% and 22.68%, respectively, and the compressive strength at 7 d and 28 d was enhanced by 11.80% and 6.45%, respectively. The XRD patterns, SEM images and hydration exothermic analysis indicated that MCPTS could accelerate cement hydration, increase heat release, and promote the formation of a denser hydration product structure, thereby improving mechanical properties. The underlying mechanism was mainly as follows, i.e., the carboxylic acid ion network formed by PTA hydrolysis could chelate Ca²⁺ and optimize the structures of CH crystals and C-S-H gels. MCC dispersed stress concentration through the fiber bridging effect. The synergistic effect of the two components realized the performance enhancement of cement-based materials.

Vanadium-based phosphate composite (VPC) can be used as a highly promising candidate for sodium-ion battery cathode materials due to its excellent structure stability and flexible voltage adjustability. However, some inherent limitations such as low intrinsic conductivity and low ion diffusion, lead to an inferior rate capability and an insufficient cycle stability in VPC materials. Efforts are dedicated to the improvement of cathode materials, such as bulk structure regulation and surface coating modification. Among them, carbon coating is usually applied to modify the inherently low conductivity of polyanion-type cathodes. The graphitization degree of pyrolytic carbon is restricted due to the limitation of VPC sintering temperature. This restriction results in a marginal enhancement of the electronic conductivity in carbon-coated VPC. To compensate for this deficiency, highly conductive carbon materials such as GO and CNTs are often incorporated into the fabrication process of VPC materials. Nevertheless, the utilization of these carbon materials can lead to a significant increase in production costs. It is thus crucial for improving the conductivity of VPC composite and simultaneously regulating the local electronic structure of vanadium ions to develop carbon materials with high cost-effectiveness and conductivity.

A certain amount of sodium citrate (Na₃C₆H₅O₇) was subjected to a sintering treatment in N₂ atmosphere at 800 ℃ for 2 h with a heating speed of 5 ℃‧min^-1. After natural cooling, the resultant black powder was then immersed in a dilute solution of HCl (2 mol·L^-1) for 24 h to remove all sodium-containing compounds. Subsequently, graphene-like nanosheets (marked as GNS) as the product were collected via filtering, repeated rinsing with ultrapure water and ethanol, and finally drying at 80 ℃ for overnight.

Vanadium pentoxide (V₂O₅, 1 mmol) and oxalic acid dihydrate (H₂C₂O₄·2H₂O, 2 mmol) were dissolved in 30 mL ultrapure water. After being stirred at 60 ℃ for 30 min, the initially orange turbid solution gradually transformed into a clear green solution. Subsequently, ammonium dihydrogen phosphate (NH₄H₂PO₄, 2 mmol) and sodium fluoride (NaF, 3 mmol) were added into the green solution above. Meanwhile, different specific quantities (i.e., 0.025, 0.033 g and 0.041 g) of GNS powder were individually dispersed into 10 mL ethyl alcohol under ultrasonic agitation for 5 min to obtain a uniform dispersion solution. The green solution was then added to the dispersion solution above. The mixture solution was subjected to continuous stirring at 60 ℃ until the gel was formed. Afterwards, the obtained gel was dried in an oven at 80 ℃ for overnight, and then ground into a fine powder. Finally, the resultant powder was first sintered at 350 ℃ for 5 h and subsequently in N₂ atmosphere at 600 ℃ for 8 h with a heating rate of 3 ℃·min^-1. The vanadium-base phosphate composites prepared with 0.025, 0.033 g and 0.041 g GNS powder were denoted as VPC-GN6, VPC-GN8 and VPC-GN10, respectively. For comparison purpose, a pristine VPC without GNS was prepared by the same method as for GNS modified VPC samples and labeled as P-VPC.

A novel biphasic-VPC composite (Bis-VPC), composed of high-capacity Na₃V₂(PO₄)₂F₃ (NVPF) and high-stability Na₃V₂(PO₄)₃ (NVP), is effectively prepared by a facile sol-gel assisted solid-state method, and facilitated by the incorporation of GNS. The results obtained from the XRD, XPS and Rietveld refinement demonstrate that the incorporation of an appropriate amount of GNS effectively modulates the content of the NVP phase in VPC composites, while simultaneously broadening the transport channels of Na⁺. Furthermore, The results of Raman spectra, SEM/TEM images, and EIS measurements indicate that GNS can suppress the uncontrolled growth and agglomeration of particles, and facilitate the construction of an efficient ion/electron conductive network. As a result, the electronic conductivity of the optimized sample is significantly enhanced by several orders of magnitude from the 1.25×10^-9 S·cm^-1 to 1.06×10^-4 S·cm^-1. Simultaneously, the VPC-GN8 shows a D_Na+ value of 1.20×10^-12 cm²·s^-1, surpassing that of the P-VPC (5.43×10^-13 cm²·s^-1). The optimized sample also exhibits a high reversible specific capacity of 118.7 mAh·g^-1 at 0.2 C and maintains an excellent capacity retention of 90.4% after 5000 cycles at 20 C. These results indicate that the optimization of phase components through incorporating an appropriate amount of GNS and the construction of highly conductive networks can expand Na⁺ migration channels, facilitate ion and electron transport, and enhance electronic conductivity, thereby improving the durability under high-rate conditions.

In this study, the incorporation of GNS could effectively mitigate the fluorine loss during the synthesis process, thereby facilitating the increase of NVPF phase and improvement of the ionic conductivity of Bis-VPC material. The introduction of GNS constructed an interconnected three-dimensional porous architecture within the matrix of Bis-VPC particles, effectively mitigating the uncontrolled growth and agglomeration of particles and accelerating the transport of both ions and electrons. In addition, the generated porous structure also increased the interface between Bis-VPC particles and electrolyte. Consequently, the modified sample exhibited improved reversible capacity, exceptional rate performance and ultra-long cycle life. This novel modification strategy, which enhanced ion and electronic conductivity through graphene like nanosheets, could accelerate the application of high-energy-density vanadium-based phosphate cathode materials in large-scale energy storage for SIBs.

Cement is a fundamental material for global infrastructure. Global cement production is projected to exceed 4.5 billion tons by 2030. The cement industry contributes about 7.5% of global anthropogenic carbon dioxide (CO₂) emissions. These emissions mainly come from fossil fuel combustion and limestone decomposition during the calcination process. Replacing fossil fuels with concentrated solar energy (CSE) for clinker calcination is a key pathway to achieve carbon neutrality in this sector. The CSE technology can concentrate solar radiation up to 7000 times and generate ultra-high temperatures of above 3000 K. These conditions can meet the thermal requirements for cement clinker production.

The spectral mismatch between cement materials and solar radiation as a critical bottleneck limits the efficiency of solar calcination.. The solar spectrum concentrates its energy in the visible (400-700 nm) and near-infrared (NIR, 700-2500 nm) bands. Most cement raw materials, such as calcium carbonate (CaCO₃), silicon dioxide (SiO₂), and aluminum oxide (Al₂O₃), are wide-bandgap materials. These materials absorb mainly in the ultraviolet region and are nearly transparent to visible and NIR light. This transparency leads to a low solar-to-thermal conversion efficiency. Iron oxide (Fe₂O₃) and iron-bearing ferrite minerals have narrower bandgaps of 2.0-2.2 eV. These minerals offer a stronger light absorption in the solar spectrum. This study was to investigate high-ferrite cement (HFC) clinkers to use the high absorption of the iron phase for better photothermal conversion. The calcination performance in electric furnace and solar furnace was compared and the first-principles calculations were performed. The goal was to reveal the photothermal coupling mechanism that could enable low-temperature and rapid clinker formation.

Three high-ferrite cement raw meals were prepared with analytical-grade reagents. These samples, named HFC-16, HFC-18, and HFC-20, were designed with different mass fractions of tetracalcium aluminoferrite (C₄AF, 16%, 18%, and 20%), respectively. All raw materials were ground and passed through a 200-mesh sieve. The sintering was carried out in a conventional electric elevator furnace and a high-flux solar simulator, respectively. The solar simulator used a xenon lamp array to mimic the solar spectrum (AM1.5). This simulator generated a peak heat flux of > 1800 kW/m² at the focal plane.

For the experiments in the electric furnace, the samples were heated to 800 ℃ and held for 30 min. The samples were then heated at 1000, 1200 ℃, or 1375 ℃ and held for 2 h, respectively. For the experiments in the solar furnace, the samples were rapidly heated to 800 ℃ and held for 1 min. They were then heated to the target temperature and held for 5 min. All the samples were rapidly cooled after firing. The phase composition of each sample was analyzed by X-ray diffraction (XRD). The Rietveld refinement was used for quantitative phase analysis. The optical properties were measured by ultraviolet-visible (UV-Vis) spectrophotometry in the range of 200-2500 nm. The total solar absorptance was calculated by the AM1.5 solar irradiance distribution. The electronic structures were simulated by a software named Vienna Ab initio Simulation Package (VASP). The simulations were based on the Density Functional Theory (DFT) with the GGA-PBE functional and a Hubbard U correction for Fe 3d orbitals.

The UV-Vis spectra of the raw materials show that wide-bandgap oxides (i.e., CaO, SiO₂, Al₂O₃) have a weak absorption in the solar spectrum region. Their absorptance values are all below 20%. Fe₂O₃ is a main absorber among all the raw materials. Its solar absorptance reaches 71.1%. As a result, increasing the Fe₂O₃ content in the raw meal improves the overall light absorption. The solar absorptance of the raw meal increases from 56.6% for HFC-16 to 60.5% for HFC-20. The light absorption of the clinker minerals depends on the calcination temperature. At 1000 ℃, the absorptance decreases slightly. This decrease is due to the decomposition of CaCO₃ into weakly absorbing CaO and the low crystallinity of intermediate phases. At 1200 ℃, the absorptance increases sharply. The iron phase mineral formed at 1200 ℃ shows a solar absorptance of 83.9%. This value is greater than that of the raw Fe₂O₃. For the clinker sample HFC-20, the total light absorptance is 75.6% at 1375 ℃.

The results by the First-principles calculations explain the mechanism behind this enhancement. In the high-temperature ferrite solid solution (C₄AF), Fe³⁺ ions occupy both tetrahedral and octahedral sites. This mixed coordination induces a crystal field splitting and creates diverse intermediate energy levels. The substitution of Al³⁺ for Fe³⁺ also introduces lattice defects. These defects create dense defect states within the bandgap. The density of states (DOS) analysis indicates that Fe 3d orbitals dominate the conduction band minimum. O 2p orbitals dominate the valence band maximum. The strong O 2p → Fe 3d transitions are responsible for the intense broadband absorption in the visible and NIR regions.

The comparison between the two heat sources shows a clear photothermal coupling effect in the solar furnace. The XRD patterns indicate that the solar-calcined samples processed at a thermocouple-measured temperature of only 800 ℃ already contain distinct silicate mineral phases (i.e., tricalcium silicate, C₃S, and dicalcium silicate, C₂S). In the conventional electric furnace, these phases only form at 1200 ℃. This result indicates that the iron phase absorbs a high-intensity photon energy locally and lowers the formation temperature of clinker minerals by approxiamtely 400 ℃. The electric furnace transfers heat slowly through conduction from the surface to the interior. The solar furnace delivers energy directly to the reactive iron-bearing sites. This direct energy delivery greatly accelerates the solid-state reaction kinetics.

At the final sintering temperature of 1375 ℃, the two methods both produce clinkers with the target mineral phases (i.e., C₃S, C₂S, tricalcium aluminate C₃A, and C₄AF). No free CaO appears in either case. This result confirms that the solar furnace can fully sinter cement clinker. The Rietveld refinement of the XRD patterns shows that the solar-calcined clinker exhibits broader diffraction peaks than the electric furnace clinker. The rapid heating rate and the unique photothermal environment in the solar furnace likely caused this broadening. Smaller crystallite sizes or higher lattice defect concentrations are the probable reasons. These findings indicate that solar calcination saves energy and changes the microstructural evolution of the cement minerals.

Based on the UV-Vis absorption testing and XRD analysis of raw materials, raw meals, and samples calcined at different temperatures, the overall light absorption intensity of the raw meal increased significantly as the Fe₂O₃ content in the raw meal increased. Furthermore, the light absorption intensity of the iron phase in the clinker minerals increased with increasing the calcination temperature. At 1200 ℃, its light absorption rate reached 83%. The light absorption intensity of the clinker also increased with the calcination temperature, reaching 75.6% at 1375 ℃. More importantly, the iron phase could trigger a photothermal coupling effect when calcined in a simulated high-concentration solar furnace, significantly lowering the formation temperature of clinker minerals. The results by the XRD Rietveld refinement and hydration calorimetry indicated that, compared with the electric furnace clinker, the simulated concentrated solar calcined clinker (SF-HFC) exhibited diffraction peak broadening characteristics. This could demonstrate that the photothermal effect of the iron phase significantly reduced the calcination temperature of cement clinker and lowered the production energy consumption, providing a material design strategy for high-efficiency and low-carbon cement manufacturing.

In recent years, Portland cement production in China has exceeded 1.8 billion tonnes per year, while CO₂ emissions from limestone decarbonation and fuel combustion remain high (i.e., ≈1.1 billion tonnes), accounting for ~8% of the national total. Replacing limestone with Ca-rich, non-carbonate solid wastes (e.g., recycled concrete powder, RCP) represents a promising pathway toward low-carbon clinker production. The RCP mainly consists of quartz and hardened cement paste. The RCP with higher paste fractions is reported to have lower clinker formation temperatures. Previous studies indicate that Ca(OH)₂, unhydrated clinker particles, and certain minor elements (e.g., S) can facilitate clinkering. C-S-H is a dominant phase in hardened cement paste (>55%). Upon heating (≈500-700 ℃), C-S-H undergoes dehydration and structural depolymerization/rearrangement, potentially generating reactive Ca-Si intermediates that may affect clinkering reactions. However, most previous work treated a hardened cement paste as an integrated entity, and the specific role of C-S-H in governing clinker mineral formation, reaction kinetics, and microstructural evolution remains insufficiently understood.

To decouple the multiphase effects of RCP, this study used synthetic C-S-H to replace quartz, thereby isolating the contribution of C-S-H to clinkering reactions, phase evolution, and kinetics.

C-S-H was hydrothermally synthesized using Ca(OH)₂ and SiO₂ nanoparticles at a CaO/SiO₂ molar ratio of 1.2. Its thermal evolution was preliminarily characterized by X-ray diffraction (XRD). C-S-H lost a long-range order at ~800 ℃ and recrystallized into C₂S and wollastonite (CS) after heating to 900 ℃. At 1000 ℃, the crystallite sizes were ~15 nm for C₂S and ~50 nm for CS (the Williamson-Hall method).

Five raw meals were designed with a silica modulus (SM) of 2.8, an alumina modulus (IM) of 1.8, and a lime saturation factor (KH) of 0.91. The reference mix used analytical-grade SiO₂ together with CaCO₃, Al₂O₃·2SiO₂·2H₂O, and Fe₂O₃. In the remaining mixes, C-S-H progressively replaced SiO₂ (and the corresponding fraction of CaCO₃), with increasing the silicon substitution ratio of C-S-H to SiO₂ from 25% to 100% (on a Si basis). Pellets (Φ 30 mm × 7 mm) were pressed at 40 MPa, dried at 105 ℃, heated in a muffle furnace at 10 ℃/min to selected temperatures, and followed by air quenching.

The phase evolution of clinkers was quantified by X-ray diffraction (XRD) coupled with Rietveld refinement using the ICSD structure models and ZnO as an internal standard. To suppress the dominant endotherm from CaCO₃ decarbonation and enhance clinkering-related thermal signals at a high temperature, CaO was used instead of CaCO₃ in the tests of thermogravimetry-differential scanning calorimetry (TG-DSC), and the derived kinetic parameters were interpreted comparatively as apparent values. The non-isothermal TG-DSC measurements were performed at 5-20 K/min in N₂, and apparent activation energies and kinetic models were evaluated by the Flynn-Wall-Ozawa (FWO) isoconversional method.

Introducing C-S-H into raw meals produces a pronounced exothermic peak associated with C₂S formation at ~870 ℃, consistent with the low-temperature decomposition and recrystallization behavior of C-S-H. When quartz serves as a silicon source, C₂S formation kinetics are well described by a phase-boundary-controlled (R3) model, with an apparent activation energy of 540 kJ/mol. In contrast, when C-S-H serves as a silicon source, the best-fit model shifts to the Avrami-Erofeev (A2), and the higher activation energy (797 kJ/mol) can be attributed to a structural rearrangement coupled with C-S-H recrystallization. The Arrhenius analysis further shows that lnA increases from 54.5 to 84.0; accordingly, the instantaneous reaction rate (dα/dt) at α = 0.5 and T = 900 ℃ increases from 0.43 to 7.60 min^-1, indicating a great kinetic compensation effect likely associated with the disordered/nanostructured nature of C-S-H and the enlarged effective reaction interface.

Consistently, the XRD-detectable onset temperature for C₂S formation decreases from 1000-1100 ℃ (quartz) to 900 ℃ (C-S-H), and the C₂S content is increased by 10-24% at the same sintering temperatures (i.e., 900-1300 ℃). The incorporation of C-S-H also increases the C₃S content by 5-15% at 1350-1450 ℃. Moreover, a high defect density of C-S-H and nanocrystal formation during heating contributes to crystallite refinement, reducing the C₂S crystallite size from 87 nm to 66 nm and the C₃S size from 160 nm to 121 nm.

Mechanistically, C-S-H enhances clinker burnability via (i) structural depolymerization/rearrangement at a lower temperatures, (ii) a higher defect density and early formation of nanocrystalline products that promote C₂S/C₃S nucleation, and (iii) a reduced effective CaO transport requirement because C-S-H (at Ca/Si ratio of 1.2) supplies part of the Ca needed for C₂S formation, thereby shortening the effective CaO diffusion distance.

Using C-S-H as a silicon source could markedly accelerate solid-state reaction kinetics (0.43 min^-1→ 7.60 min^-1), lower the XRD-detectable onset temperature of C₂S formation (1000-1100 ℃→ 900 ℃), and promote the formation of both C₂S and C₃S. In addition, the recrystallization products of C-S-H provided abundant nucleation sites and led to refined silicate crystallites. These findings could offer a mechanistic guidance for clinkering with RCP containing high hardened cement paste (C-S-H-rich) fractions toward low-carbon clinker production.

The review outlines future research directions, such as the development of large-area material growth and transfer techniques, the design of novel device structures, and the integration of multi-functional systems. 2D materials are expected to play a crucial role in the advancement of neuromorphic computing through interdisciplinary collaboration and continuous innovation, paving a way for the development of artificial intelligence, the Internet of Things, and big data technologies.

This review provides the research progress on a comprehensive, first-principles-based examination in elemental-doped graphene as electrode materials for sodium-ion batteries. It examines the governing mechanisms behind the physical properties and electrochemical performance of doped graphene anode materials. The microscopic physicochemical nature of doped graphene's characteristics is revealed via the detailed atomic-scale simulations and analysis.

The first-principles calculations reveal the distinct mechanisms by which different main-group element dopants affect the physical properties of graphene. Nitrogen (N) and boron (B) doping significantly enhance a sodium-ion adsorption capability and a diffusion performance via modifying the electronic structure of graphene, while maintaining a good structural integrity, thus exhibiting excellent overall performance. Sulfur (S) doping optimizes diffusion kinetics via expanding the interlayer spacing, though its adsorption capability and cycling stability require improvement. Fluorine (F) doping enhances adsorption capability via charge transfer mechanisms but suffers from a lower structural stability. Silicon (Si) doping increases the open-circuit voltage, however, its volumetric effect leads to degraded diffusion performance and structural stability.

The electrochemical performance analysis reveals that nitrogen-doped graphene exhibits a balanced performance in terms of specific capacity and capacity retention rate, making it suitable as a high-performance anode material for sodium-ion batteries. Boron-doped graphene achieves the maximum discharge specific capacity, however, its lower capacity retention rate limits its use to scenarios prioritizing a high energy density. Sulfur-doped graphene demonstrates the optimum cycling stability, but its relatively low specific capacity makes it suitable for applications demanding exceptionally long cycle life. Fluorine-doped graphene and silicon-doped graphene require a further performance optimization. Specifically, fluorine-doped graphene suffers from a low specific capacity and a poor capacity retention, limiting its practical viability. Silicon-doped graphene experiences degraded diffusion performance and structural stability due to its volumetric effect, necessitating a further investigation into doping concentration and structural design.

Based on the first-principles calculations, this review delves into the interactions between doped graphene and the electrolyte, predicting the composition and structure of the solid electrolyte interphase (SEI) film. Some strategies are explored to engineer a more stable SEI layer via simulating the SEI formation process, thereby suppressing the electrolyte decomposition and enhancing the cycling stability and safety of batteries.

Based on the research on doped graphene anode materials, novel doping elements and co-doping strategies can be explored to develop sodium-ion battery anodes with an enhanced adsorption capacity, a reduced diffusion energy barriers, and a superior structural stability. Leveraging the first-principles calculations to predict electrochemical performance of emerging dopants, we optimize doping concentrations and atomic configurations to improve electronic conductivity and ion diffusivity, thus propelling the performance enhancement of sodium-ion batteries.

The research on elemental doping of graphene anode materials for sodium-ion batteries synergistically integrates big data analytics, leveraging extensive experimental and computational datasets to identify and predict dopant effects on the material performance. This data-driven approach enables an accelerated translation from laboratory prototypes to industrial-scale production, reducing manufacturing costs and expediting the commercialization of sodium-ion battery technologies. Consequently, it establishes a robust support framework for developing eco-friendly energy materials and their sustainable implementation.