Li Doping Research Articles

Enhancing Structural of P2-Type Layered Cathode Material for Sodium-Ion Batteries through Cu Substitution

Oxygen-redox-based layered cathode materials for Sodium-ion batteries (SIBs) have been recognized as a promising alternative to Lithium-ion batteries (LIBs) due to high energy density and additional capacity in the high voltage. However, their irreversible oxygen-redox activity during cycling leads to structural distortion and capacity fading. Herein, we introduce a layered P2-Na0.75[Li0.15Cu0.15Mn0.7]O2 cathode material, in which Cu substitution improves electro-conductivity and cyclability. Na0.75[Li0.15Cu0.15Mn0.7]O2 delivers a reversible capacity of 170 mAh g-1 at 0.1C in Na cell. Operando-XRD measurement display the material maintain the P2 structure even upon full Na+ extraction and insertion. Furthermore, magnetic susceptibility provide further information Cu2+/Cu3+, Mn3+/Mn4+, and O2-/(O2)n- ion distribution in Na0.75[Li0.15Cu0.15Mn0.7]O2. This research highlight the effect of Li and Cu doping in P2-type layered materials and the contribution of oxygen redox to additional capacity in high voltages, suggesting the potential for future development of cathode materials for Na-ion batteries with oxygen redox.

Enhancing Electrochemical Performance of Co-Free Cathode Materials for Lithium-Ion Batteries Via Surplus Lithium Incorporation

Interest in electric vehicles has grown in recent years due to increased government subsidies due to environmental problems, improvements in infrastructure such as electric vehicle charging stations, and increased mileage. As interest in electric vehicles grows, not only the small battery market that used to enter mobile phones, but also the medium and large battery markets are growing at a rapid pace every year. As the medium and large battery market grows. Among the many sections of LIBs, the most utilized material in the cathode material is a layered cathode material, with representative examples being LiNi1-x-yCoxMnyO2 (NCM), LiNi1-x-yCoxAlyO2 (NCA), and LiCoO2 (LCO). Currently, the biggest roadblock in reducing the price of commercially used batteries is related to transition metal, the main raw material for cathode materials, especially cobalt, which is highly volatile in price. Since more than half of the world's cobalt deposits are in Democratic Republic of the Congo (DRC), the price of cobalt is very fluctuating and, in extreme instances, may reach four times that of Ni, the second-most expensive transition metal. In addition to economic factors, the usage of cobalt in Africa is becoming less desirable for political and ethnic reasons. Recent attempts have been undertaken to produce low Co, Co-free layered cathode materials for these reasons, but now, only Li-and Mn-rich materials and high voltage spinel LiNi0.5Mn1.5O4, disorder rock-salt (DRX) are being studied as materials for low Co, Co-free.In the layered structure, which is a representative cathode material, the biggest reason why Co-free materials have difficulty in commercialization lies in the various important roles that Co plays in layered materials. Most well-known function of using cobalt is the suppression of cation disorder within the layered structure. Due to the comparable ionic sizes of Ni2+ (0.69A) and Li+ (0.74A), cation disorder arises when Ni2+ occupies the octahedral site of Li+ (0.74A) in the Li layer. Ni2+ ion in the Li layer inhibits Li ion diffusion in the Li layer during charging and discharging. In addition, since the Ni-O bond is shorter than the Li-O bond, the Li layer slab distance near where cation disorder occurs is shorter, and Li ion experiences a higher energy barrier during diffusion. The cation disorder negatively impacts the reversible specific capacity and rate capability for these reasons. If Co is substituted with Ni, the Li+/Ni2+ cation disorder is minimized as the oxidation state of Ni approaches Ni3+; nevertheless, as shown in several Ni-rich materials, the battery life performance and thermal stability worsen rapidly. If Co is replaced with Mn, since Mn is present as Mn4+ in the layered material, the oxidation state of Ni is close to Ni2+ to meet charge neutrality, and the Li+/Ni2+ cation disorder is enhanced further. For these reasons, in order to commercialize the Co-free layered structure, it is important to find a material that replaces Co but does not bring about a trade off in battery performance and structure.In this paper, we provide a Li-surplus method for reducing cation disorder caused by the direct substitution of Co with Li (Fig. 1A). Li doping decreases the cation disorder ratio from 6.9% when x=0 to 1.84% when x=0.1 in Li1+x(Ni0.75Mn0.25)1-xO2 (Li-surplus NM75 or LS-NM75). As the ratio of cation disorder dropped, both the specific reversible capacity and rate capability, which were recognized as cation disorder's largest problem, improved. In fact, studies on improving the performance of materials using excess Li have already been conducted in several studies. However, in the case of these papers, only the predictable level of performance improvement, in which the rate capability is improved due to the reduction of cation disorder, was shown. However, in this study, in addition to the previously known diffusivity characteristic performance improvement, we determined that surplus Li decreased internal cracks in secondary particles and validated that surplus Li inhibited the creation of nanopores in primary particles, which are the origin of particle cracks. In particular, improvements in mechanical properties and cycle life were demonstrated due to these effects when surplus Li was employed. In addition, while synthesizing a layered material, the intercalation phenomena of Li into the layered structure was enhanced, and the synthesis process optimization minimized the cation disorder ratio and increased performance. Figure 1

Theoretical Study of the Reactive Mechanisms of Li-Doped Ni-Based Oxygen Carrier during Chemical Looping Combustion.

Ni-based oxygen carriers (OCs) are considered promising materials in the chemical looping combustion (CLC) process. However, the reactivity of Ni-based OCs still offers the potential for further enhancement. In this work, the Li doping method has been employed for the modification of Ni-based OCs. The reactivity and microreaction mechanisms of different concentrations of Li-doped Ni-based OCs with CO in CLC are clarified using density functional theory (DFT) simulation. The structures, energy, and density of states are obtained through computational investigation of the reaction path in elementary reactions. The results show that (1) the adsorption energies of CO molecules on NiO surfaces with 4, 8, and 12% Li doping concentrations are -0.53, -0.48, and -0.54 eV, respectively, demonstrating an enhanced reactivity compared to that of pure NiO (-0.41 eV); (2) the calculation of the transition state indicates that the most favorable pathway for CO oxidation takes place on the surface of NiO with an 8% Li doping concentration, exhibiting the lowest energy barrier of 0.51 eV; and (3) the oxygen vacancy formation energies on the surface of NiO are 3.05, 2.30, and 2.10 eV for 4, 8, and 12% doping concentrations, respectively. Additionally, the decrease in oxygen vacancy formation energies exhibits a gradual decline with an increasing Li doping concentration. By comprehensive analysis, 8% is considered to be the optimal doping concentration of NiO for chemical looping combustion.

Dry Reforming of Methane over Li-Doped Ni/TiO2 Catalysts: Effect of Support Basicity

In this research, we investigate the impact of Li doping on a TiO2 support, synthesized through the sol-gel method, with a focus on varying the aging time. Our objective is to elucidate how aging duration and doping influence the surface basicity, thereby mitigating carbon formation and amplifying the catalytic efficacy of Ni-loaded catalysts (15 wt.%). Essential characterization techniques encompass X-ray diffraction, H2-TPR, FE-SEM, N2-physisorption, DLS, FTIR, and Raman spectroscopies. Our findings reveal that extended aging periods promote the development of a basic character, attributable to oxygen defects within TiO2. This inherent trait bears significant implications for catalyst performance, stability, and carbon formation during the reaction. Remarkably, the catalyst with the highest catalytic activity and stability boasts an 85% relative basicity, a property also induced by incorporating lithium into the TiO2 support.

Simultaneously promoting the surface/bulk structural stability of Fe/Mn-based layered cathode for sodium ion batteries

Layered sodium iron manganese oxide cathodes have attracted great interest owing to their high specific capacity and cost-effective metal resources, while the detrimental phase transitions and surface structural degradation severely limit their commercial applications. In this work, the bulk and surface structure stability of a P2-Na0.67Fe0.5Mn0.5O2 cathode can be synergically enhanced by a one-step Li/Nb co-doping strategy. Structural characterizations reveal that Li doping promotes the formation of P2/O3 biphasic structure and makes the unfavorable P2-OP4 phase transition convert into a smooth solid-solution reaction. Nb doping enhances the mobility of sodium ions and forms strong Nb-O bonds, thereby enhancing the stability of the TMO2 layer structure. In particular, the Nb element induces the surface reorganization of an atomic-scale NaNbO3 coating layer, which could effectively prevent the dissolution of metals and surface side reactions. The synergistic mechanism of enhanced electrochemical performance is proved by multiple characterizations during cycling. As a result, the as-prepared Na0.67Li0.1Fe0.5Mn0.38Nb0.02O2 exhibits improved capacity retention of 85.4 % than raw material (45.7 %) after 100 cycles at 0.5C (1C = 174 mA g−1) within 2.0–4.0 V. This co-regulating strategy provides a promising approach to designing highly stable sodium-ion battery cathodes. Furthermore, a full cell of Na0.67Li0.1Fe0.5Mn0.38Nb0.02O2 with hard carbon displays excellent cycling stability (85.1 % capacity retention after 100 cycles), making its commercial operation possible. This synergistic strategy of biphasic structure and surface reorganization is a critical route to accelerate the application of layer oxide cathodes.

Comparison between Lithium Substitution and Doping on the Physical and Piezoelectric Properties of Lead-Free BCZT Ceramics

Defects generation in ceramics by element substitution or doping may improve their properties. However, different results will be obtained even though the same element is involved due to different mechanisms. Ceramics Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) is one of the potential candidates to replace lead-based material PZT. However, the conventional method requires high-temperature calcination and sintering process to synthesize this material. Thus, Lithium (Li) can act as the sintering aid to lower the temperature at the same time, the properties of piezoelectric can be enhanced. In this paper, the structural, physical, and piezoelectric performance of lead-free Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) ceramics with Lithium Li substitution and doping, synthesized by the solid-state reaction method were studied. The substitution of Li increases the density, ρ and piezoelectric coefficient, d33 of BCZT which are 4.075 g/cm3 and 304.6 pC/N, respectively. These results demonstrate that Li substitution is more beneficial to the piezoelectric properties than doping because it produces higher grain boundary resistance and activation energy and has lower conductivity than doping. This can provide a definite strategy during the chemical composition design and manufacture of BCZT ceramics.

Lithium and Cesium Doping on the Properties of ZTS Crystals (Tris (Thiourea) Zinc (II) Sulphate)

The influence of alkali metals (Cs and Li) doping on the properties and crystal growth of tris(thiourea)zinc(II)sulphate crystals by slow evaporation solution growth technique at 30ºC has been investigated. Each metals as dopant incorporate into the crystal lattice even at its low concentrations is well confirmed by energy dispersive X – ray spectroscopy (EDS). In the powder X –ray diffraction (XRD), high intense peaks are observed for all doped specimens due to stress developed in the crystal because of doping when compared to pure one. Single crystal XRD reveals a nominal increase in the cell parameter values of the doped samples compared to pure. Presence of each alkali metal (Li, Cs) quantitatively is confirmed by inductively coupled plasma (ICP) technique. It is interesting to observe the enhancement of fluorescence intensity of pure ZTS by the dopant in the photoluminescence (PL) spectra. The grown crystals are also characterized by FT-IR, UV-Visible and TG/DSC methods. The second harmonic generation (SHG) efficiency, an essential character required for the single crystals to identify the non-linear optical (NLO) property, was performed by kurtz powder technique. 2.The characterization results of influence of various concentration of Mn (II) ion on the properties and crystalline perfection of ammoniumdihydrogenphosphate (ADP) crystal are presented. Using water as a solvent pure, 1 and 20 mol % of Mn (II) ion in the form manganese (II) sulphate added ADP crystals are prepared by slow evaporation solution growth technique (SEST). Well faceted grown crystals are characterised by different experimental techniques. The presence of Mn (II) in the doped specimens is confirmed by energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma (ICP) technique. High resolution X- ray diffraction (HRXRD) study of the doped samples when compared with the pure ADP crystal reveals interesting features. In the single crystal XRD studies, the dopants have not altered the lattice parameter values and the crystal system of pure ADP. Reduction in the intensity of peaks is observed in the powder XRD of all the doped samples. It is interesting to enhancement of fluorescence intensity of pure ADP by the dopants in the photoluminescence (PL) spectra. The surface morphology of the crystals is studied by scanning electron microscopy (SEM). The grown crystals are also characterized by FT-IR, UV-Vis and TG/DTA methods. The second harmonic generation (SHG) efficiency, which is an essential character required for the single crystals to identify the nonlinear optical (NLO) property, is performed by Kurtz powder technique. Increasing in concentrations of dopant enhance the SHG efficiency of ADP crystal.

The effect of Li doping on superconductivity of SiH4(H2)2 from first-principles calculations

From first-principles calculations, we calculated the crystal structure, electronic properties, and phonon properties of SiH4(H2)2 and LiSiH4(H2)2 at 180 GPa, respectively. The electronic properties of SiH4(H2)2 and LiSiH4(H2)2 were studied by analyzing the band structure, density of states (DOS), charge density and Mulliken population. The results show that both substances are metals. However, the lower N(Ef) of SiH4(H2)2 indicates that the Cc structure behaves in a weak metal nature at 180 GPa. Moreover, after Li atom doping, significantly improved the H atoms near the Fermi surface states density (from 0.04 to 0.34 states/eV). And when the pressure reaches 350 GPa, the DOS of H is as high as 1.02 states/eV. This leads to a higher Tc. And the analysis of phonon dispersion and phonon state density (PDOS) shows that the dynamic stability of LiSiH4(H2)2 is better. By comparing the electronic and phonon properties of SiH4(H2)2 and LiSiH4(H2)2, we can find that the superconductivity of SiH4(H2)2 can be improved by doping Li atoms to a certain extent.

ZnO nanoparticles with altered structural and optical traits by Cu and Li doping for elevated photocatalytic activity toward organic pollutants

Doping of copper and lithium on zinc oxide nanoparticles (NPs) has attracted a great deal of attention due to their morphological change, large surface-to-volume ratio, and enhanced physical properties. In this study, Cu-doped ZnO NPs (CZO) and Li-doped ZnO NPs (LZO) were synthesized by one-step hydrothermal method. The obtained nanostructures were characterized using analytical techniques such as XRD, UV-visible spectroscopy, FTIR, SEM, and TEM. The XRD analysis of CZO and LZO revealed hexagonal nanorod structures possessing a dominant peak at (101) hkl plane. From SEM imaging, it was observed that the doping concentration of Cu- and Li- onto the ZnO nanoparticles had an effect on the morphology and size of the obtained nanorods. EDAX analysis confirmed the presence of Cu and Li ions in the ZnO lattice structures. The photocatalytic degradation of CZO and LZO was performed using two dyes namely Rhodamine B and methylene orange under tungsten bulb light source. CZO and LZO showed a degradation of 56.51%0.61% and 63.97%% for Rhodamine B; 45.68%0.39% and 40.01%% of degradation was observed for methylene orange dye.

Stable cycling performance of lituium-doping Na3−xLixV2(PO4)3/C (0 ≤ x ≤ 0.4) cathode materials by Na-site manipulation strategy

Na3V2(PO4)3 (NVP) has become a hot material in the research field of sodium-ion batteries (SIBs) as a result of its unique structural advantages. Unfortunately, the poor electronic conductivity and ion diffusion ability fundamentally limit the practical development of NVP. Considering the above defects, a series of Li+ doped Na3−xLixV2(PO4)3/C cathode materials for SIBs are synthesized through hydrothermal assisted sol–gel method. The cell volume steadily decline with the raise of Li+ doping amount, which is consistent with the usual doping effect. Moreover, with the increase of lithium doping amount, Li+ preferentially occupies Na(2) site and then occupies Na(1) site. Through the first principles calculation, it is clear that the introduction of Li+ can significantly reinforce the conductivity of the material system and diminish the electron localization phenomenon. The analysis of (116) crystal plane by TEM shows that Li doping will reduce the interplanar spacing. The change of V valence during the charge–discharge process of Na2.8Li0.2V2(PO4)3/C is consistent with that of NVP by V element XANES characterization. There is no conventional phase transition phenomenon in the ex-situ XRD high-voltage charging state. The above facts indicate that lithium doping obtains a stable solid solution NVP. The electrochemical test results show that Na2.8Li0.2V2(PO4)3/C can provide an amazing reversible capacity of 116.9 mAh/g (theoretical capacity of 117 mAh/g) and capacity retention rate of 99.82 % after 500 cycles. GITT results show that Li+ can significantly increase the Na+ diffusion coefficient of the material. Such excellent electrochemical performance is attributed to the fact that the doping of Li+ activates the activity of Na+ in Na(2) site and improves the reaction efficiency.

Revealing the Adsorption Mechanisms of Methanol on Lithium-Doped Porous Carbon through Experimental and Theoretical Calculations.

Previous reports have shown that it is difficult to improve the methanol adsorption performance of nitrogen and oxygen groups due to their low polarity. Here, we first prepared porous carbon with a high specific surface area and large pore volume using benzimidazole as a carbon precursor and KOH as an activating agent. Then, we improved the surface polarity of the porous carbon by doping with Lithium (Li) to enhance the methanol adsorption performance. The results showed that the methanol adsorption capacity of Li-doped porous carbon reached 35.4 mmol g-1, which increased by 57% compared to undoped porous carbon. Molecular simulation results showed that Li doping not only improved the methanol adsorption performance at low pressure, but also at relatively high pressure. This is mainly because Li-modified porous carbon has higher surface polarity than nitrogen and oxygen-modified surfaces, which can generate stronger electrostatic interactions. Furthermore, through density functional theory (DFT) calculations, we determined the adsorption energy, adsorption distance, and charge transfer between Li atom and methanol. Our results demonstrate that Li doping enhances the adsorption energy, reduces the adsorption distance, and increases the charge transfer in porous carbon. The mechanism of methanol adsorption by Li groups was revealed through experimental and theoretical calculations, providing a theoretical basis for the design and preparation of methanol adsorbents.

Engineering and regulating the interfacial stability between Li1.3Al0.3Ti1.7(PO4)3-based solid electrolytes and lithium metal anodes for solid-state lithium batteries

InCl3@Li1.3Al0.3Ti1.7(PO4)3-F (InCl3@LATP-F) solid electrolyte powders are designed and fabricated by coating a uniform InCl3 layer on the surface of F--doped Li1.3Al0.3Ti1.7(PO4)3 (LATP-F) solid powders via a feasible wet-chemical technique. The assembled Li/InCl3@LATP-F/Li cell can undergo longer cycles of 2500 h at 0.4 mA cm−2 without obvious increases in the overvoltage compared to 1837 h for the Li/LATP-F/Li cell, and the interfacial resistance demonstrates a sharp decrease from 3428 to 436 Ω for the Li/InCl3@LATP-F/Li cell during the first 500 h. Importantly, the assembled LiCoO2/InCl3@LATP-F/Li cell delivers a high discharge specific capacity of 126.4 mAh g−1 with a 95.42% capacity retention ratio after 100 cycles at 0.5 C, and the value easily returns to 112.9 mAh g−1 when the current density is abruptly set back to 0.1 C after different rate cycles. These improved results can be mainly attributed to the fact that the InCl3 layer with a lithiophilic nature can react with lithium metal to form a Li-In alloy, which can guarantee homogeneous lithium ion flux to avoid the accumulation of ions/electrons across the interface and suppress the growth of lithium dendrites. Moreover, the InCl3 layer can prevent direct contact of the LATP-F solid electrolyte and lithium metal to effectively alleviate the reduction reaction of Ti4+ and preserve the structural stability of the composite electrolyte. Therefore, this work may provide an effective strategy to engineer and regulate the interfacial stability between LATP solid electrolytes and lithium metal anodes for LATP-type solid-state lithium batteries.

First-Principles Study of Structural, Electronic and Magnetic Properties of Lithium Doped Hexa]gonal Boron Nitride Monolayer (h-BN)

We examine the structural, electronic, and magnetic properties of pure and lithium doped hexagonal boron nitride (h-BN) monolayer using density functional theory (DFT) based on first-principles calculations. LiB site is more conducive to doping than LiN site, according to the values of formation energy, which are found to be 13.06 eV and 18.50 eV, respectively. Metallic behavior may be seen in the band structures for both the LiB site and LiN in nature. At both sites, the density of states (DOS) is asymmetric for spin-up and spin-down electrons. This suggests that systems with Li doping on h-BN are magnetic.

Exceeding the hydrogen gravimetric capacity targets in cubic bundles of Li doped carbon nanotubes

Enhanced hydrogen adsorption is considered in 〈111〉 cubic arrangements of Li doped single walled carbon nanotubes. In particular we have considered the +Ω and +Σ cubic arrangements of (10,0) carbon nanotubes at different Li content and pressure at both cryogenic (T=100K) and room (T=300K) temperatures. The adsorption isotherms with different Li content have been calculated by Grand Canonical Monte Carlo simulations using accurate parameters for the Li−H2 interaction that were previously obtained on the basis of density functional theory calculations. We show that for the lighter +Σ〈111〉 cubic arrangement, Li doping is able to enhance the hydrogen uptake at such an extent that the U.S. Department of Energy ultimate gravimetric target is exceeded at room temperature and P=10MPa. We also find that heavy Li doping (greater than 20% of carbon atoms) becomes detrimental in terms of gravimetric adsorption performances because the H2 uptake increase is overcompensated by the heaviness of the absorbing medium. The system volumetric capacity improvement is not as good as the gravimetric and is still not sufficient to fulfill the needs of onboard hydrogen storage for light-duty fuel cell vehicles in the thermodynamic and Li content ranges explored.

Li-decorated graphdiyne for ultrahigh-performance CO2 capture and separation over N2

The development of CO2 adsorbents with high adsorption and separation performances is important to solve severe environmental problems. Herein, two-dimensional graphdiyne acetylene rings doped with different concentrations of lithium atoms (1/2/6Li-GDYs) were introduced as potential adsorbents for CO2 capture and separation by using Grand Canonical Monte Carlo and Density Functional Theory methods. According to the structure analysis, Li atoms could stably bind to GDY with a binding energy of 1.04 – 2.77 eV/atom; 1/2/6Li-GDYs had high cohesive energy of 7.02 – 7.54 eV/atom. Electronic structure analysis confirmed the large charge transfer and strong interaction between Li atoms and GDY. The pore physical properties of Li-GDYs indicated that the pore volume, porosity, and pore size provided a favorable environment for CO2 adsorption. Among Li-GDYs, 2/6Li-GDYs exhibited an ultra-high CO2 adsorption capacity of 11.91 mmol/g at 298 K and 100 kPa, and was superior to other metal-modified adsorbents. The CO2/N2 selectivity in 1/2/6Li-GDYs reached ∼ 168, ∼311, and ∼ 1021 at 298 K and 100 kPa. Gas distribution analysis revealed a broad CO2 distribution consisting of multilayer adsorption peaks around Li and adjacent C atoms, illustrating the significant effect of Li and Li-connected C atoms on CO2 adsorption. Interaction analysis showed that Li doping enhanced the CO2-framework interaction more significantly than the N2-framework interaction, resulting in ultra-high CO2 adsorption capacity and CO2/N2 selectivity. The results of this work highlight 1/2/6Li-GDYs as ultrahigh-performance adsorbent materials for CO2 adsorption and separation over N2.

Enhancement of Hydrogen Adsorption on Spray-Synthesized HKUST-1 via Lithium Doping and Defect Creation.

We prepared HKUST-1 (Cu3BTC2; BTC3- = 1,3,5-benzenetricarboxylate) using a spray synthesis method with Li doping and defect created via partial replacement of H3BTC with isophthalic acid (IP) to enhance the H2 adsorption capacity. Li-doping was performed by incorporating LiNO3 in HKUST-1 via spray synthesis and subsequent thermal treatment for decomposing NO3-, which enhances H2 uptake at 77 K and 1 bar per unit mass and per unit area from 2.37 wt% and 4.16 molecules/nm2 for undoped HKUST-1 to 2.47 wt% and 4.33 molecules/nm2, respectively. Defect creation via the replacement of the BTC3- linker with the IP2- linker slightly in HKUST-1 skeleton did not affect H2 uptake. Both Li-doping and defect creation significantly enhanced H2 uptake to 3.03 wt%, which was caused by the coordination of Li ions with free carboxylic groups of the created defects via IP replacement.

Na vacancies and Li doping synergistically constructed P2-type Na0.5Li0.1Ni0.2Mn0.7O2 as high-performance cathode material for sodium-ion batteries

P2-type Na-Ni-Mn layered oxides are potential cathode materials for energy storage in sodium-ion batteries, but have low cycling stability and limited Na storage capacity due to complex phase transitions. Herein, co-regulating vacancies and doping were implemented to address the issue, resulting in the successful synthesis of hexagonal columnar P2-Na0.5Li0.1Ni0.2Mn0.7O2 through a solid-state synthesis method. Increased interlayer spacing of Na+ can offer numerous active sites for Na+ insertion and extraction. P2-Na0.5Li0.1Ni0.2Mn0.7O2 exhibits an impressive initial discharge capacity of 139.1 mAh g−1 and 78.5 % capacity retention after 100cycles at 1.0C, which is a significant improvement compared to the pristine Na0.7Ni0.3Mn0.7O2. Overall, our study significantly boosts the electrochemical performance of P2-type materials, thus offering exciting avenues for the advancement of high-performance sodium-ion batteries.

Spin textures induced in n-doped solid electrolytes

A strongly insulating solid-state electrolyte may become conducting upon n-doping. On the basis of ab initio calculations, we demonstrate how the charge-to-spin conversion takes place in Li-doped lithium tantalate. Due to an excess of electrons induced by each Li dopant, the low-conduction 5d band of the nearest Ta shifts down and crosses the Fermi level. The band structure of the doped material displays its spin polarization, whilst the relatively large spin–orbit coupling stimulates the spin textures. Additionally, we anticipate that spin-orbitronic effects may be generated by the charge current via n-doped solid-state electrolytes.

Elastic, piezoelectric, and electronic properties of K1−xMxNbO3 (M = Li, Na): A first-principles study

The structural, elastic, piezoelectric, and electronic properties of K1−xMxNbO3 (M = Li, Na) were investigated by first-principles calculations. The results show that the modifications have effects on the elastic properties of KNbO3 and strengthen the anisotropy. Na and Li doping can slightly improve the piezoelectric stress tensor (e33) and piezoelectric strain tensor (d33) of KNbO3. With the increase in the x value from 0 to 0.5 in K1−xMxNbO3, the d33 value is improved from 24.4 to 36.3 pC/N (M = Na) and 41.5 pC/N (M = Li), and the piezoelectric property is improved by 1.49 and 1.70 times with the modifications of Na and Li, respectively. This conclusion is consistent with the result of Born effective charge and band structure results. The Born effective charge average values (Z*̄) for K and Nb atoms in K0.5M0.5NbO3 (M = Li, Na) are slightly increased compared to those in KNbO3. KNbO3 has an indirect bandgap, while Na and Li doping makes K0.5Na0.5NbO3 or K0.5Li0.5NbO3 a direct bandgap semiconductor. This study may provide a theoretical insight into Na and Li modified KNbO3 for their piezoelectricity.

Comparative analysis of the substitutional and interstitial Li-, Na-doped, and Li∖Na-Codoped Cu2O via density functional calculations

A comprehensive comparative study utilizing HSE06 and GGA density functional calculations was conducted to investigate the impact of Li and Na doping, as well as their co-doping, on the physical properties of cuprous oxide (Cu2O). This study examined three possible structures, including substitution of Li, Na, and Li/Na for Cu, and interstitial Li, Na, and Li/Na in both tetrahedral and octahedral sites. The results of the study revealed that the introduction of alkaline atoms leads to structural changes in Cu2O, and the degree of lattice parameter extension or compression varies across different doping sites. Additionally, the study provided an estimation of the enthalpies of formation for pure and doped-Cu2O, which is useful in understanding the stability of the systems. Notably, the study found that Li, Na, and Li/Na-doped-Cu2O were more readily formed in substitutional sites rather than in interstitial sites. The findings also indicate that substitutional doping and co-doping exhibit a large band gap while maintaining the properties of a p-type semiconductor, while interstitial doping and co-doping of Cu2O led to significant absorption enhancement and n-type conductivity characteristics. These results provide new insights into the structural and electronic properties of Cu2O, with the findings suggesting that interstitial doping of Li and Na could be a promising approach for improving the absorption of visible light in Cu2O-based solar cells, thus contributing to the development of more efficient and cost-effective photovoltaic devices.