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Some spinel chromium oxides with the chemical formula ACr2O4 exhibit magnetic-induced multiferroicity due to the special spiral spin order. However, because of the relatively low temperature of the ordered spiral phase, this kind of multiferroicity generally displays a limited coexistence of magnetic and ferroelectric orders in a narrow temperature range. The Jahn–Teller (JT) effect, serving as a crucial link between charge and orbit degrees of freedom, can facilitate efficient modulation of multiferroic properties. In this work, Ni1−xCuxCr2O4 (0 ≤ x ≤ 0.2) series are synthesized by occupying the same Wyckoff site with two kinds of JT ions. The microstructure and JT distortion can be distinctly influenced by varying the doping level of Cu2+ ions. Particularly, Ni0.85Cu0.15Cr2O4 (x = 0.15) presents the pronounced JT distortion, accompanied by observation of dielectric anomaly at ∼78 K, resulting from spin–orbit coupling. This implies that the JT effect can significantly promote the contribution of spin–orbit coupling in magnetoelectric correlation. Moreover, the magnetodielectric effect induced by intrinsic magnetoelectric coupling is confirmed in Ni0.85Cu0.15Cr2O4 over a wide temperature range of 10–200 K, which is much higher than the Néel temperature of ∼85 K. It indicates that spin–orbit coupling based on the JT effect could overcome the constraint of magnetic order to achieve effective control on electric polarization performance under an applied magnetic field, thereby showing broad application prospects. [ABSTRACT FROM AUTHOR]

Accurate quantum dynamics simulations of nonadiabatic processes are important for studies of electron transfer, energy transfer, and photochemical reactions in complex systems. In this comparative study, we benchmark various approximate nonadiabatic dynamics methods with mapping variables against numerically exact calculations based on the tensor-train (TT) representation of high-dimensional arrays, including TT-KSL for zero-temperature dynamics and TT-thermofield dynamics for finite-temperature dynamics. The approximate nonadiabatic dynamics methods investigated include mixed quantum–classical Ehrenfest mean-field and fewest-switches surface hopping, linearized semiclassical mapping dynamics, symmetrized quasiclassical dynamics, the spin-mapping method, and extended classical mapping models. Different model systems were evaluated, including the spin-boson model for nonadiabatic dynamics in the condensed phase, the linear vibronic coupling model for electronic transition through conical intersections, the photoisomerization model of retinal, and Tully's one-dimensional scattering models. Our calculations show that the optimal choice of approximate dynamical method is system-specific, and the accuracy is sensitively dependent on the zero-point-energy parameter and the initial sampling strategy for the mapping variables. [ABSTRACT FROM AUTHOR]

Quantum dynamics simulations are becoming a standard tool for simulating photo-excited molecular systems involving a manifold of coupled states, known as non-adiabatic dynamics. While these simulations have had many successes in explaining experiments and giving details of non-adiabatic transitions, the question remains as to their predictive power. In this work, we present a set of quantum dynamics simulations on cyclobutanone using both grid-based multi-configuration time-dependent Hartree and direct dynamics variational multi-configuration Gaussian methods. The former used a parameterized vibronic coupling model Hamiltonian, and the latter generated the potential energy surfaces on the fly. The results give a picture of the non-adiabatic behavior of this molecule and were used to calculate the signal from a gas-phase ultrafast electron diffraction (GUED) experiment. Corresponding experimental results will be obtained and presented at a later stage for comparison to test the predictive power of the methods. The results show that over the first 500 fs after photo-excitation to the S2 state, cyclobutanone relaxes quickly to the S1 state, but only a small population relaxes further to the S0 state. No significant transfer of population to the triplet manifold is found. It is predicted that the GUED experiments over this time scale will see signals related mostly to the C–O stretch motion and elongation of the molecular ring along the C–C–O axis. [ABSTRACT FROM AUTHOR]

A time-dependent vibrational electronic coupled-cluster (VECC) approach is proposed to simulate photo-electron/UV-VIS absorption spectra as well as time-dependent properties for non-adiabatic vibronic models, going beyond the Born–Oppenheimer approximation. A detailed derivation of the equations of motion and a motivation for the ansatz are presented. The VECC method employs second-quantized bosonic construction operators and a mixed linear and exponential ansatz to form a compact representation of the time-dependent wave-function. Importantly, the method does not require a basis set, has only a few user-defined inputs, and has a classical (polynomial) scaling with respect to the number of degrees of freedom (of the vibronic model), resulting in a favorable computational cost. In benchmark applications to small models and molecules, the VECC method provides accurate results compared to multi-configurational time-dependent Hartree calculations when predicting short-time dynamical properties (i.e., photo-electron/UV–VIS absorption spectra) for non-adiabatic vibronic models. To illustrate the capabilities, the VECC method is also successfully applied to a large vibronic model for hexahelicene with 14 electronic states and 63 normal modes, developed in the group by Aranda and Santoro [J. Chem. Theory Comput. 17, 1691, (2021)]. [ABSTRACT FROM AUTHOR]

Understanding the protonation behavior of metal-oxo water oxidation catalysts is essential to improve catalyst efficiency and long-term performance, as well as to tune their properties for specific applications. In this work, we explore the basicity and protonation effects of the highly active water oxidation catalyst [(Mn4O4) (V4O13) (OAc)3]3− using density functional theory. We computed the relative free energies of protonation in a systematic fashion for all symmetry-inequivalent O atoms, where the presence of multiple oxidation states from Mn 4 IV to Mn 4 III and a rich Jahn–Teller isomerism adds a significant amount of complexity. For high oxidation states, the compound behaves like some other polyoxometalates, showing protonation preferably at the terminal and μ2-bridging O atoms of the vanadate cap. However, upon reduction, eventually, the protonation preference switches to the cubane O atoms, mostly driven by a strong increase in basicity for O atoms located along the Jahn–Teller axes. Our work further evidences that protonation can potentially lead to several chemical transformations, like disproportionation and charge transfer to vanadium, dissociation of ligands, or the opening of the cubane structure. Our simulated UV/Vis absorption spectra additionally provide valuable insights about how the protonation of the catalyst could be tracked experimentally. Overall, our analysis highlights the complexity involved in the protonation of heterometallic polyoxometalate clusters. [ABSTRACT FROM AUTHOR]

A first implementation of analytic gradients for spinor-based relativistic equation-of-motion coupled-cluster singles and doubles method using an exact two-component Hamiltonian augmented with atomic mean-field spin–orbit integrals is reported. To demonstrate its applicability, we present calculations of equilibrium structures and harmonic vibrational frequencies for the electronic ground and excited states of the radium mono-amide molecule (RaNH2) and the radium mono-methoxide molecule (RaOCH3). Spin–orbit coupling is shown to quench Jahn–Teller effects in the first excited state of RaOCH3, resulting in a C3v equilibrium structure. The calculations also show that the radium atoms in these molecules serve as efficient optical cycling centers. [ABSTRACT FROM AUTHOR]

Infrared spectra of C60+ and C120+, obtained via helium messenger spectroscopy, are reported. For C60+, new absorption features have been found just above the discrete vibrational spectrum of the ion. The absorption profile, which is broad and contains little structure, is assigned to one or more electronic absorption transitions and is in good agreement with predictions from time-dependent density functional theory. It seems likely that the transitions observed correspond to excitation from the 2A1u electronic ground state to one or both of the low-lying 2E1u and 2E2u electronic states previously identified as dark states of C60+. These states presumably become optically bright through vibronic coupling and specifically the Jahn–Teller effect. In the case of C120+, the simplest positively charged oligomer of C60, we present the first vibrational spectrum of this ion. Through a comparison with theory, vibrational features are best explained by a peanut-shaped structure for C120+, maintained by covalent bonding between the two C60 units. We have also discovered electronic transitions for C120+, which, similar to C60+, lie just above the vibrational spectrum. [ABSTRACT FROM AUTHOR]

The orbital ordering (OO) resulting from the partial occupancy of the t2gd subshell of the transition metals in KBF3 (B = Sc, Ti, Ffe, Co) perovskites, and the many possible patterns arising from the coupling between the B sites, have been investigated at the quantum mechanical level (all electron Gaussian type basis set, B3LYP hybrid functional) in a 40 atoms supercell. The numerous patterns are distributed into 162 classes of equivalent configurations. For each fluoroperovskite, one representative per class has been calculated. The four compounds behave similarly: an identical dependence of the energy and volume (or cell parameters) on the OO pattern; the spanned energy interval is small (1 to 2 mEh per formula unit), suggesting that most of the configurations are occupied at room and even at low temperature. A linear model, taking into account the relative orbital order in contiguous sites, reproduces the energy order in the full set for each compound, suggesting that it could be used for studying OO in larger supercells. [ABSTRACT FROM AUTHOR]

Polarons can control carrier mobility and can also be used in the design of quantum devices. Although much effort has been directed into investigating the nature of polarons, observation of defect-related polarons is challenging due to electron-defect scattering. Here we explore the polaronic behavior of nitrogen-vacancy (NV) centers in a diamond crystal using an ultrafast pump-probe technique. A 10-fs optical pulse acts as a source of high electric field exceeding the dielectric breakdown threshold, in turn exerting a force on the NV charge distribution and polar optical phonons. The electronic and phononic responses are enhanced by an order of magnitude for a low density of NV centers, which we attribute to a combination of cooperative polaronic effects and scattering by defects. First-principles calculations support the presence of dipolar Fröhlich interaction via non-zero Born effective charges. Our findings provide insights into the physics of color centers in diamonds. Polaronic behavior associated with the Jahn-Teller effect has been studied in NV centers in diamond but other types of polarons are possible. Here the authors study electro-optical response of NV centers using ultrafast pump-probe spectroscopy and find an enhancement due to cooperative polaronic effect. [ABSTRACT FROM AUTHOR]

In decisions under risk, more numerate people are typically more likely to choose the option with the highest expected value (EV) than less numerate ones. Prior research indicates that this finding cannot be explained by differences in the reliance on explicit EV calculation. The current work uses the attentional Drift Diffusion Model as a unified computational framework to formalize three candidate mechanisms of pre-decisional information search and processing—namely, attention allocation, amount of deliberation, and distorted processing of value—which may differ between more and less numerate people and explain differences in decision quality. Computational modeling of an eye-tracking experiment on risky choice demonstrates that numeracy is linked to how people allocate their attention across the options, how much evidence they require before committing to a choice, and also how strongly they distort currently non-attended information during preference formation. Together, especially the latter two mechanisms largely mediate the effect of numeracy on decision quality. Overall, the current work disentangles and quantifies latent aspects of the dynamics of preference formation, explicates how their interplay may give rise to manifest differences in decision quality, and thereby provides a fully formalized, mechanistic explanation for the link between numeracy and decision quality in risky choice. [ABSTRACT FROM AUTHOR]

Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced cavitation bubble, we associate the dynamic bubble size (fluid velocity) and bubble lifetime to the laser energy supplied—a control parameter in experiments. Employing different channel cross-section shapes, sizes and lengths, we demonstrate the characteristic scales for velocity, time and energy to depend solely on the channel geometry. Contrary to the generally assumed absence of instability in low Reynolds number flows ( < 1000 ), we report a momentary flow distortion that originates due to the boundary layer separation near channel walls during flow deceleration. The emergence of distorted laminar states is characterized using two stages. First the conditions for the onset of instabilities is analyzed using the Reynolds number and Womersley number for oscillating flows. Second the growth and the ability of an instability to prevail is analyzed using the convective time scale of the flow. Our findings inform rational design of microsystems leveraging pulsatile flows via cavitation-powered microactuation. [ABSTRACT FROM AUTHOR]

Na4Mn1.5Fe1.5(PO4)2P2O7 (NMFPP), with its low cost and high energy density, is essential for accelerating the commercialization of sodium‐ion batteries. However, its practical application is limited by serious voltage hysteresis and detrimental Jahn‐Teller distortions. Herein, a high operating voltage and superior stable Nb‐doped NMFPP with fewer intrinsic anti‐site defects are elaborately designed by the reconstruction of the crystal lattice and electronic distribution. By introducing higher charge density Nb─O bonds, the lengths of Mn‐O bonds are shortened, enhancing lattice stability. As a result, the lattice volume contracted during Na+ extraction/insertion is decreased with niobium‐modified Na4(Mn0.5Fe0.5)2.94Nb0.06(PO4)2P2O7, mitigating lattice distortion from the Jahn‐Teller effect and increasing the capacity retention after 1000 cycles from 57.5% to 82.3%. More importantly, the delayed effect of Mn2+ involvement in redox reactions is significantly reduced, raising the average operating voltage from 3.32 to 3.64 V and increasing the overall energy density by 13%. This study opens new avenues to develop advanced sodium‐ion battery cathode materials with high energy density and long calendar life for energy storage. [ABSTRACT FROM AUTHOR]

The Mn-Ni-based oxides used as cathodes for Na-ion batteries (NIBs) are inexpensive and exhibit high capacities, but the Jahn–Teller distortions of Mn3+ rapidly decrease the capacity. Here, Li-doped P3-type Na2/3Ni1/3Mn2/3O2 (named Li-NaNMO) was prepared with a microwave-assisted sol–gel method. After structural analyses, we found that Li doping decreased the content of Mn3+ and replaced it with Mn4+, the content of Mn3+ was reduced from 66.2% for NaNMO to 32.4% for Li-NaNMO, the content of Mn4+ was increased from 33.8% to 67.6%, and the content of Ni2+ varied to balance the charge, which was verified with XRD and XPS results. As the cathode of a Na-ion battery (NIB), NaNMO showed a capacity retention rate of 60% after the 100th cycle over the voltage range 2.0–4.2 V, while Li-NaNMO exhibited good cycling stability and 90% retention under the same testing conditions, which resulted from suppression of the Jahn–Teller effect and the improved conductivity. It also displayed a good rate performance (73 mAh/g at 200 mA/g), and the increased conductivity was confirmed by an EIS analysis. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) are considered as a beneficial complement to lithium‐ion batteries for large‐scale energy storage systems because of the abundant sodium resources. However, the relatively large ionic radius of Na+ inevitably results in a huge volume change and sluggish electrochemical reaction kinetics, which put forward higher requirements for electrode materials. Among the reported cathode materials for SIBs, the manganese hexacyanoferrate (MnHCF) with the merits of large channels for fast sodium ion transport, high theoretical capacity and low cost has attracted extensive attention. In this review, the recent achievements of MnHCF for SIBs are focused. The key challenges of MnHCF limiting the practical application include the interstitial water, vacancies, low electronic conductivity, and the Jahn‐Teller effect. Subsequently, the mainstream strategies to boost the sodium storage performance of MnHCF are summarized (such as structure regulation, surface coating, hybridization with carbon materials, and element substitution). Finally, the potential research directions are also proposed to promote the practical application of MnHCF for SIBs. This review is expected to provide a whole insight into exploring MnHCF cathode materials for SIBs. [ABSTRACT FROM AUTHOR]

Fabricating efficient non‐platinum‐group‐metal catalysts for the oxygen reduction reaction (ORR) in proton‐exchange membrane fuel cells still remains a big challenge. This study creates a unique bamboo‐like architecture of Mn and Fe single atomic sites (SASs) anchored on core‐shell structure of nanopaticles@carbon nanotubes (MnFe SASs/NPs@CNTs) via a precursor route, where the Fe nanoparticles (NPs) (identified as γ‐Fe and Austenite) are confined into CNTs, such an architecture exhibits compelling ORR activity and durability in 0.1 m HClO4. Experiments and calculations both reveal that the electron donor–acceptor paradigm between Mn SASs and Fe NPs launches a lattice‐electron coupling mechanism not only increasing occupation of π‐antibonding orbital in Mn−*O intermediates but also rising Jahn–Teller effect, thereby destabilize the Mn−*O intermediate and eventually facilitate the potential‐limiting step from *O to *OH. Such a coupling activation of the ORR‐inert Mn SASs greatly improves ORR performances of MnFe SASs/NPs@CNTs. [ABSTRACT FROM AUTHOR]

Despite their low cost and high specific capacity, the practical use of monoclinic Mn‐based Prussian blue analogs (Mn‐PBAs) is limited by poor cycling stability, primarily due to the structural degradation caused by the multiple phase transitions and Jahn–Teller effect associated with Mn3+ ions throughout the entire cycle. Herein, by synergistic incorporation of low‐cost Cu and Fe into the manganese sites of Mn‐PBAs, the ternary PBAs (T‐PBAs) achieve solid solution reaction of Na+ extraction and insertion, successfully eliminating the inherent multi‐phase transition from the sodium storage mechanism of T‐PBAs. Ex situ analysis and density functional theory calculations are employed to confirm that T‐PBAs consistently maintain a cubic phase with smaller lattice distortion rather than occur in conventional three‐phase transition during the charging and discharging processes, forcefully inhibiting the structural degradation of T‐PBAs. Therefore, the T‐PBAs showcase unprecedented cycling stability at both room temperature (10 000 cycles at 1 A g−1) and −20 °C (over 3000 h, 4200 cycles at 0.2 A g−1 without distinct capacity degradation), More importantly, when paired with commercial hard carbon, the T‐PBAs based sodium‐ion batteries exhibit excellent capacity retention (2000 cycles 76.8%), showcasing their immense potential in practical applications. [ABSTRACT FROM AUTHOR]

The olivine‐type compound LiMnxFe1‐XPO4 (LMFP) combines the advantageous characteristics of LiFePO4 and LiMnPO4, including high energy density, extended cycle life, eco‐friendliness, and cost‐effectiveness. However, its application is limited by certain challenges such as low electronic conductivity and stability issues related to the Jahn‐Teller effect induced by Mn3+, which hinder its scalability. Here, we introduce an innovative approach by applying nitrogen‐doped carbon layers, derived from chitosan as both a carbon and nitrogen sources, to encapsulate LMFP. This encapsulation significantly improves LMFP′s electrochemical performance compared to those using sucrose‐derived carbon coatings. The LMFP cathode with nitrogen‐doped carbon coating exhibits a specific capacity of 156.8 mAh/g at 0.1 C, achieved a first‐cycle Coulombic efficiency of 96.8 %, and maintained a capacity retention rate of 94.6 % after 200 cycles at 1 C. This new method of employing chitosan for producing nitrogen‐doped carbon coatings holds great promise for enhancing the usability of LMFP in broader applications. [ABSTRACT FROM AUTHOR]

Abstract Crystals of YGa3(BO3)4, YAl3(BO3)4, EuGa3(BO3)4 and EuAl3(BO3)4 with copper alloy were studied by electron paramagnetic resonance and X-ray diffraction analysis. The lattice parameters and coordinates of copper-doped boron atoms were determined. The study of EPR spectra showed that copper is in the divalent state and replaces aluminum ions with C2 node symmetry. In YAl3(BO3)4:Cu crystals, a ligand structure exists due to the interaction of copper electrons with yttrium nuclei. The parameters of the spin Hamiltonian describing the behavior of the Cu2+ spectrum have been determined. The deviation of the Z-axis spectra from the C3 axis by 54(1)° is due to Jahn-Teller vibronic interaction and monoclinic distortion. In the EuGa3(BO3)4 crystal, a new spectrum 2 was found, which also belongs to divalent copper but is observed at an excited state 31 cm−1 away from the ground state. Above 70 K, an isotropic EPR line with a width of 450 Gs, g = 2.1, appears and exists up to room temperature.

The PPy-coated Na 0.67 Ni 0.33 Mn 0.67 O 2 cathode undergoes reversible structural evolution during charging/discharging process. The Na-ion full cell exhibits a high capacity retention of 88.2% after 150 cycles. [Display omitted] • PPy-coated P 2-Na 0.67 Ni 0.33 Mn 0.67 O 2 is prepared by in situ polymerization process. • The PPy-coated cathode showed enhanced cycling stability and rate capability. • The PPy coating layer can inhibit side reactions stemming from the electrolyte. P 2-Na 0.67 Mn 0.67 Ni 0.33 O 2 is a promising cathode material for sodium ion batteries (SIBs) due to its low cost, high theoretical capacity, and non-toxicity. However, it still suffers from unsatisfactory cycling stability mainly incurred by the Jahn-Teller effect of Mn3+ and electrolyte decomposition on the electrode/electrolyte interface. Herein, the P 2-Na 0.67 Ni 0.33 Mn 0.67 O 2 @PPy (NNMO@PPy) composite applied as cathode materials for SIBs is obtained by introducing conductive polypyrrole (PPy) as coating layer on the P 2-Na 0.67 Ni 0.33 Mn 0.67 O 2 (NNMO) microspheres. Numerous physical characterization methods indicate that the PPy layer was uniformly coated on the surface of NNMO microspheres without change in phase structure and morphology. The PPy coating layer can alleviate Mn dissolution and effectively suppress the side reactions between the electrolyte and electrode during cycling. The optimal NNMO@PPy-9 with 9 wt% PPy delivers a high capacity of 127.4 mAh/g at the current density at 150 mA g−1, an excellent cyclic stability with high capacity retention of 80.5 % after 300 cycles, and enhanced rate performance (169.3 mAh/g at 15 mA g−1 while 89.8 mAh/g at 600 mA g−1). Furthermore, hard carbon (−)//NNMO@PPy-9 (+) full cell delivers a high energy density of 305.1 Wh kg−1 and superior cycling stability with 88.2 % capacity retention after 150 cycles. In-situ X-ray diffraction experiment and electrochemical characterization verify the highly reversible structure evolution and robust P 2-type phase structure of NNMO@PPy-9 for fast and stable Na+ diffusion. This effective strategy of using conductive PPy as a coating layer may provide a new insight to modify NNMO surface, improving the cycling stability and rate capability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Na 3.4 Mn 0.7 Ti 0.3 Cr(PO 4) 3 /C cathode material is prepared by a simple sol–gel method. • Ti substitution shortens the average bond length of TM-O. • Ti substitution can suppress the Jahn-Teller effect of Na 4 MnCrPO 4 cathode material. • Ti substitution reduces the R ct of cathode and suppress interface side reactions. The sodium superionic conductor Na 4 MnCr(PO 4) 3 gains increasing attention owing to its three-dimensional structure and the three-electron reaction. However, rapid structure degradation during cycling is the major challenge for its practical application. Herein, Ti4+ is utilized to replace a portion of Mn2+ in Na 4 MnCr(PO 4) 3. The low redox voltage and d 0 electronic configuration of the Ti4+ ions are helpful to suppress the structure alteration and improve electronic conduction. Consequently, the as-prepared Na 3.4 Mn 0.7 Ti 0.3 Cr(PO 4) 3 /C cathode exhibits a remarkable good 91.0% capacity retention after 500 cycles at 10C rate, with exceptional rate capacities of 99.5 mAh g−1 and 81.0 mAh g−1 at 5C and 10C rate, respectively. Furthermore, based on ≈2.86-electron reactions involving Mn2+/Mn3+ (3.5 V), Mn3+/Mn4+ (4.1 V), Cr3+/Cr4+ (4.3 V), and Ti3+/Ti4+ (2.1 V), the material can provide an energy density of approximately 541.6 Wh kg−1, slightly surpassing that of Na 4 MnCr(PO 4) 3. Ex-situ XRD investigation further elucidates that throughout the entire charge–discharge process, the Ti-substituted material experiences highly reversible solid-solution and two-phase reactions. Additionally, Ti substitution can greatly promote the interfacial charge transfer of the material and suppress the decomposition of the electrolyte during cycling. This work might open a new insight for designing sodium-ion battery cathode materials with good cycling stability and high energy density. [ABSTRACT FROM AUTHOR]

The O‐type layered nickel oxides suffer from undesired cooperative Jahn–Teller distortion stemming from Ni3+ ions and undergo multiple biphasic structural transformations during the insertion/extraction of large Na+ ions, posing a significant challenge to stabilize the structural integrity. We present here a systematic investigation of the impact of substituting 5 % divalent (Mg2+) or trivalent (Al3+ or Co3+) ions for Ni3+ to alleviate Na+ion ordering and perturb the Jahn–Teller effect to enhance structural stability. We gauge a fundamental understanding of the Mg−O and Na−O or Mg−O−Na bonding interactions, noting that the ionicity of the Mg−O bond deshields the electronic cloud of oxygen from Na+ ions. Furthermore, calculations of the Van Vleck distortion modes reveal a relaxation of NiO6 octahedra from Jahn–Teller distortion and a reduced electron density at the interlayer with Mg2+ substitution. Long‐range (operando X‐ray diffraction) and short‐range (magic angle spinning nuclear magnetic resonance) structural analyses provide insights into reduced ordering, allowing a stable continuous solid solution. Overall, Mg‐substitution results in a high‐capacity retention of ~96 % even after 100 cycles, showcasing the potential of this strategy for overcoming the structural instabilities and enhancing the performance of sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

In this study, the electrochemical performance of Na 3 MnTi(PO 4) 3 material has been improved through cation/anion-dual regulation. This dual regulation provides a strategy for phosphate materials as an advanced cathode for sodium-ion batteries. [Display omitted] Na 3 MnTi(PO 4) 3 (NMTP) emerges as a promising cathode material with high-performance for sodium-ion batteries (SIBs). Nevertheless, its development has been limited by several challenges, including poor electronic conductivity, the Mn3+ Jahn-Teller effect, and the presence of a Na+/Mn2+ cation mixture. To address these issues, we have developed a cation/anion-dual regulation strategy to activate the redox reactions involving manganese, thereby significantly enhancing the performance of NMTP. This strategy simultaneously enhances the structural dynamics and facilitates rapid ion transport at high rates by inducing the formation of sodium vacancy. The combined effects of these modifications lead to a substantial improvement in specific capacity (79.1 mAh/g), outstanding high-rate capabilities (35.9 mAh/g at 10C), and an ultralong cycle life (only 0.040 % capacity attenuation per cycle over 250 cycles at 1C for Na 3.34 Mn 1.2 Ti 0.8 (PO 3.98 F 0.02) 3) when used as a cathode material in SIBs. Furthermore, its performance in full cell demonstrates impressive rate capability (44.4 mAh/g at 5C) and exceptional cycling stability (with only 0.116 % capacity decay per cycle after 150 cycles at 1C), suggesting its potential for practical applications. This work presents a dual regulation strategy targeting different sites, offering a significant advancement in the development of NASICON phosphate cathodes for SIBs. [ABSTRACT FROM AUTHOR]

To overcome the structural failure of Manganese-based Prussian blue analogue (Mn-HCF) as a cathode material of sodium ion batteries caused by Mn ion dissolution induced by Jahn–Teller effect, we coated Mn-HCF with iron-based Prussian blue (Fe-HCF) to prepare the core–shell Mn-HCF@Fe-HCF cathode material for sodium ion batteries through co-precipitation method. The research results indicate that this structure effectively blocks the direct contact between Mn-HCF and electrolyte, thereby minimizing the dissolution of Mn 3 + in the electrolyte and significantly improving the cycling stability and rate performance. The discharge capacity of this material at a current density of 0.1 C (14 mA g − 1) is 129.7 mAh g − 1 . It still has a capacity of 87.4 mAh g − 1 at a current density of 2 C (280 mA g − 1) , and still has a capacity retention rate of 84.3% (91 mAh g − 1) after 100 cycles at a current density of 0.5 C (70 mA g − 1). Compared with the capacity retention rate of 51.5% of Mn-HCF 100 cycles before coating, the cycle stability of Mn-HCF@Fe-HCF is greatly improved. The Mn-HCF@Fe-HCF material was successfully prepared through a simple coprecipitation method. When applied in sodium-ion batteries, the Mn-HCF@Fe-HCF exhibited a remarkable cycle stability of 129.7 mAh g–1 at 0.1 C, along with an impressive rate performance of 104.2 mAh g–1 at 1 C. [ABSTRACT FROM AUTHOR]

The KScF 3 perovskite has been used as a model for investigating the relative importance of the Jahn‐Teller (JT) lift of degeneracy, the ScF 6 octahedra rotation (OR), and the quadrupole‐quadrupole interaction linked to different occupancy of the Sc t 2g subshell in various sites of the unit cell (orbital ordering, OO). The group‐subgroup sequence Pm3¯m, P4mmm, P4mbm, and Pnma, supplemented by Cmmm and I4mcm, has been explored by using an all electron Gaussian type basis set, hybrid functionals, and the CRYSTAL17 code. The JT lift of degeneracy provides a stabilization about 5 times larger than the sum of the OO and OR effects. The energy gained in the transition from P4mmm to P4mbm, consisting in a rotation of the octahedra around the c axis, is 1077 μE h. From P4mbm to Pnma, additional rotations around the a and b axes are possible, and the d Sc electron can occupy a different t 2g orbital, with a total energy reduction of 2318 μE h. The rotation of the octahedra reduces the strength of superexchange: in going from P4mmm to Pnma the G‐AFM stabilization with respect to FM shrinks by a factor 4. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) reflect a strategic move for scalable and sustainable energy storage. The focus on high‐entropy (HE) cathode materials, particularly layered oxides, has ignited scientific interest due to the unique characteristics and effects to tackle their shortcomings, such as inferior structural stability, sluggish reaction kinetics, severe Jahn‐Teller effects induced lattice distortion, and poor oxygen reversibility at high voltage. This review focuses on high‐entropy oxide materials, highlighting their fundamentals, design principles, and application in layered oxide cathodes for SIBs. It delves into the growth mechanism, composition‐properties correlations, and the functional roles of high‐entropy design in enhancing the performance of layered oxide cathodes. Furthermore, it furnishes a comprehensive survey of recent advancements and persisting challenges within the domain of layered high‐entropy cathode materials, as well as offers insights into potential future research directions in line with the current state of knowledge. [ABSTRACT FROM AUTHOR]

Synthesis of Na 0.44 Mn 1- x Fe x O 2 cathode material with reduced Jahn-Teller effect. [Display omitted] Due to its stability and low cost, the tunnel-style sodium-manganese oxide (Na 0.44 MnO 2) material is deemed a popular cathode choice for sodium-ion rechargeable batteries. However, the Jahn-Teller effect caused by Mn3+ in the material results in poor capacity and cycling stability. The purpose of this experimental study is to partially replace Mn3+ with Fe3+, in order to reduce the Jahn-Teller effect of the material during charging and discharging process. The results of Raman spectroscopy and X-ray photoelectron spectroscopy confirmed that the content of Mn3+ decreased after Fe3+ doping. Electrochemical studies show that the Na 0.44 Mn 0.994 Fe 0.006 O 2 cathode has better rate performance (exhibits a reversible capacity of 87.9 mAh/g at 2 C) and cycle stability in sodium-ion batteries. The diffusion coefficient of sodium ions increases by Fe3+ doping. The excellent rate performance and capacity improvement are verified by density functional theory (DFT) calculation. After doping, the band gap decreases significantly, and the results show that the state density of O 2p increases near the Fermi level, which promotes the oxidation–reduction of oxygen. This work provides a straightforward approach to enhance the performance of Na 0.44 MnO 2 nanorods, and this performance improvement has guiding significance for the design of other materials in the energy storage domain. [ABSTRACT FROM AUTHOR]

The study is devoted to the theoretical analysis of noncollinear magnetic structures of charge-ordered manganites with a doping level of x = 3/4, 4/5. The reasons for canted and perpendicular magnetic structures to form as a result of the competition between the orbitally dependent exchange interactions in different crystallographic directions and the influence of single-ion anisotropy are considered. The mechanism of formation of predominantly noncollinear magnetic structures is shown. Trimer stripe magnetic structures with ordering along pseudo-perovskite axes xp, yp, zp = b are predicted. The presence of magnetic structure components aligned with the b axis is assumed and methods for checking the presence of such components based on field dependencies of magnetization and antiferromagnetic resonance frequencies are proposed. [ABSTRACT FROM AUTHOR]

An analysis of the features of measurements and correction of phase distortions in optical waves propagating in the atmosphere at various levels of turbulence was performed. It is shown that with increasing intensity fluctuations, the limiting capabilities of phase correction decrease, and the phase of an optical wave that has passed through a turbulence layer consists of two components: potential and vortex. It was found that even in the region of weak fluctuations there is an overlap of spectral filtering functions for intensity and phase fluctuations. Areas of turbulence inhomogeneities have been identified that will have mutual influence and negatively affect the operation of the phase meter. It is noted that correlation functions, both phase and intensity, are less susceptible to this compared to structural functions. The results of experimental studies on the reconstruction of the wavefront of laser radiation distorted by atmospheric turbulence using a Shack–Hartmann wavefront sensor during vignetting and central screening of the entrance pupil in the optical system are presented. Studies have been carried out on the propagation of laser radiation along a horizontal atmospheric path for various levels of turbulence. The results are analyzed in terms of Zernike polynomials. [ABSTRACT FROM AUTHOR]

LiFe1−xMnxPO4 with elevated energy density is becoming the next-generation olivine-type cathode. However, its long cycling stability and delivered capacities are far from perfect, chiefly induced by its intrinsically poor ionic/electrical conductivities, sluggish electrode kinetics and notable Jahn–Teller effects upon charge/discharge cycles. Aimed at overcoming these barriers, we herein propose an efficient synergistic fluorine (F)/indium (In) dual doping strategy. As confirmed from the XRD Rietveld refinement results, the doped electronegative F can interact with Mn, thereby shortening Mn–O bond lengths, strengthening the covalent bonding nature and inhibiting the Jahn–Teller distortion/Mn dissolution, whereas the In doping helps to increase the electronic conductivity of particle cathodes, and opens up the crystal lattice spacing for expediting Li+ diffusion. As a proof-of-concept demonstration, the developed F/In-doped LiFe0.5Mn0.5PO4 cathodes exhibit less adverse phase variations, showing a maximum output capacity of 158.5 mA h g−1 at 0.1C, a capacity retention ratio over 86.7% after 500 cycles, and a markedly improved Mn discharge plateau capacity and capacity retention rate (at 2C). This work may not only shed new light on understanding the anion/cation co-doping effects for LiFe1−xMnxPO4, but also offer an applicable concept to design other high-energy-density electrode species. [ABSTRACT FROM AUTHOR]

Potassium‐ion batteries (PIBs) have attracted increasing interest as promising alternatives to lithium‐ion batteries (LIBs) in large‐scale electrical energy storage systems due to the potential price advantages, abundant availability of potassium resources, and low standard redox potential of potassium. However, the pursuit of suitable cathode materials that exhibit desirable characteristics such as voltage platforms, high capacity, and long cycling stability is of utmost importance. Recently, layered transition‐metal oxides for PIBs offer great potential due to their high theoretical capacity, suitable voltage range, and eco‐friendliness. Nevertheless, the progress of KxMO2 cathodes in PIBs faces obstacles due to the detrimental effects of structural disorder and irreversible phase transitions caused by the Jahn‐Teller effect. This review provides a brief description of the origin and mechanism of the Jahn‐Teller effect, accompanied by the proposed principles to mitigate this phenomenon. In particular, the current status of KxMO2 cathodes for PIBs, is summarized highlighting the challenges posed by the Jahn‐Teller effect. Furthermore, promising strategies, such as composition modulation, synthesis approaches, and surface modification, are proposed to alleviate and suppress the Jahn‐Teller effect. These strategies offer valuable insights into the prospects of innovative cathode materials and provide a foundation for future research in the field of PIBs. [ABSTRACT FROM AUTHOR]

Studies of dodecaboride LuB12 in the temperature range of 10–300 K show that the 175Lu spectrum is broadened due to the scatter of quadrupole frequency shifts caused by the defects in the Lu sublattice. To explain the discovered hysteresis in the temperature dependence of the 175Lu linewidth, a scenario of "crystallization of structural defects" is proposed, in which the defects of the Lu sublattice, disordered at room temperature, are transformed into a more symmetrical and stable configuration with decreasing temperature, apparently due to static distortions of the boron frame caused by the cooperative Jahn–Teller effect. [ABSTRACT FROM AUTHOR]

In this work, we have observed that some chiral boron clusters ( B 16 − , B 20 − , B 24 − , and B 28 − ) can simultaneously have helical molecular orbitals and helical spin densities; these seem to be the first compounds discovered to have this intriguing property. We show that chiral Jahn–Teller distortion of quasi-planar boron clusters drives the formation of the helical molecular spin densities in these clusters and show that elongation/enhancement in helical molecular orbitals can be achieved by simply adding more building blocks via a linker. Aromaticity of these boron clusters is discussed. Chiral boron clusters may find potential applications in spintronics, such as molecular magnets. [ABSTRACT FROM AUTHOR]

The characterization of normal mode (CNM) procedure coupled with an adiabatic connection scheme (ACS) between local and normal vibrational modes, both being a part of the Local Vibrational Mode theory developed in our group, can identify spectral changes as structural fingerprints that monitor symmetry alterations, such as those caused by Jahn-Teller (JT) distortions. Employing the PBE0/Def2-TZVP level of theory, we investigated in this proof-of-concept study the hexaaquachromium cation case, [Cr(OH2)6] 3+/[Cr(OH2)6] 2+, as a commonly known example for a JT distortion, followed by the more difficult ferrous and ferric hexacyanide anion case, [Fe(CN)6] 4−/[Fe(CN)6] 3−. We found that in both cases CNM of the characteristic normal vibrational modes reflects delocalization consistent with high symmetry and ACS confirms symmetry breaking, as evidenced by the separation of axial and equatorial group frequencies. As underlined by the Cremer-Kraka criterion for covalent bonding, from [Cr(OH2)6]3+ to [Cr(OH2)6]2+ there is an increase in axial covalency whereas the equatorial bonds shift toward electrostatic character. From [Fe(CN)6]4− to [Fe(CN)6]3− we observed an increase in covalency without altering the bond nature. Distinct π back-donation disparity could be confirmed by comparison with the isolated CN− system. In summary, our study positions the CNM/ACS protocol as a robust tool for investigating less-explored JT distortions, paving the way for future applications. [ABSTRACT FROM AUTHOR]

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Coherent nuclear wavepacket behavior obtained by time-resolved spectroscopy is a good choice to capture the real-time evolution of molecular configuration. Using femtosecond time-resolved photoelectron imaging, we investigate the real-time evolution of the vibrational wavepacket of 2,5-difluoroaniline following the coherent excitation of an out-of-plane vibrational mode in the S1 state at 289.8 nm. Probed by an accidental resonance with the Rydberg states, the periodic oscillations with the frequency of 99 cm−1 are observed from the photoelectron kinetic energy (PKE) distributions, corresponding to the energy difference between the out-of-plane mode X10 of C–F bond and the band origin. Moreover, phase reversal of π rad between 0.66–0.75 and 1.00–1.08 eV is also observed in the PKE region. Combined with the scan of the potential energy surface in the ground cationic D0 state, the observed two ionization channels corresponding to different phases are attributed to the periodic geometry changes between the planar and the non-planar structures when the coherent wavepacket evolves from the initial vertical Franck–Condon region toward the global minimum of the S1 potential energy surface. [ABSTRACT FROM AUTHOR]

Highlights γ-MnO2 loaded on N-doped biomass carbon from grapefruit peel is firstly developed. The splendid cathodic properties (e.g., coulombic efficiency: ~ 100%, energy density: 553.12 Wh kg−1) are gained. The biomass strategy guaranteed via cytotoxicity test shows a clinical potential. Zn-ion storage efficiency is boosted mainly by regulating Mn–O bond and Mn domains.

A model designed to mimic the implications of the collective optical response of molecular ensembles in optical cavities on molecular vibronic dynamics is investigated. Strong molecule–radiation field coupling is often reached when a large number N of molecules respond collectively to the radiation field. In electronic strong coupling, molecular nuclear dynamics following polariton excitation reflects (a) the timescale separation between the fast electronic and photonic dynamics and the slow nuclear motion on one hand and (b) the interplay between the collective nature of the molecule–field coupling and the local nature of the molecules nuclear response on the other. The first implies that the electronic excitation takes place, in the spirit of the Born approximation, at an approximately fixed nuclear configuration. The second can be rephrased as the intriguing question of whether the collective nature of optical excitation leads to collective nuclear motion following polariton formation resulting in so-called polaron decoupled dynamics. We address this issue by studying the dynamical properties of a simplified Holstein–Tavis–Cummings-type model, in which boson modes representing molecular vibrations are replaced by two-level systems, while the boson frequency and the vibronic coupling are represented by the coupling between these levels (that induces Rabi oscillations between them) and electronic state dependence of this coupling. We investigate the short-time behavior of this model following polariton excitation as well as its response to CW driving and its density of states spectrum. We find that, while some aspects of the dynamical behavior appear to adhere to the polaron decoupling picture, the observed dynamics mostly reflect the local nature of the nuclear configuration of the electronic polariton rather than this picture. [ABSTRACT FROM AUTHOR]

Quantum master equations (QMEs) provide a general framework for describing electronic dynamics within a complex molecular system. Off-diagonal QMEs (OD-QMEs) correspond to a family of QMEs that describe the electronic dynamics in the interaction picture based on treating the off-diagonal coupling terms between electronic states as a small perturbation within the framework of second-order perturbation theory. The fact that OD-QMEs are given in terms of the interaction picture makes it non-trivial to obtain Schrödinger picture electronic coherences from them. A key experimental quantity that relies on the ability to obtain accurate Schrödinger picture electronic coherences is the absorption spectrum. In this paper, we propose using a recently introduced procedure for extracting Schrödinger picture electronic coherences from interaction picture inputs to calculate electronic absorption spectra from the electronic dynamics generated by OD-QMEs. The accuracy of the absorption spectra obtained this way is studied in the context of a biexciton benchmark model, by comparing spectra calculated based on time-local and time-nonlocal OD-QMEs to spectra calculated based on a Redfield-type QME and the non-perturbative and quantum-mechanically exact hierarchical equations of motion method. [ABSTRACT FROM AUTHOR]

Heavy element compounds with high symmetries often feature both spin–orbit coupling and vibronic coupling. This is especially true for systems with tetrahedral and octahedral symmetries, whose electronic states may be threefold degenerate and experience complicated Jahn–Teller and pseudo-Jahn–Teller interactions. To accurately describe these interactions, high quality spin–orbit vibronic Hamiltonian operators are needed. In this study, we present a unified one-electron Hamiltonian formalism for spin–orbit vibronic interactions for systems in all tetrahedral and octahedral symmetries. The formalism covers all spin–orbit Jahn–Teller and pseudo-Jahn–Teller problems in the symmetries with arbitrary types and arbitrary numbers of vibrational modes and generates Hamiltonian expansion formulas of arbitrarily high order. [ABSTRACT FROM AUTHOR]

Manganese-based layered oxides are promising cathode materials for potassium-ion batteries (PIBs) due to their low cost and high theoretical energy density. However, the Jahn-Teller effect of Mn3+ and sluggish diffusion kinetics lead to rapid electrode deterioration and a poor rate performance, greatly limiting their practical application. Here, we report a Co/Al co-substitution strategy to construct a P3-type K0.45Mn0.7Co0.2Al0.1O2 cathode material, where Co3+ and Al3+ ions occupy Mn3+ sites. This effectively suppresses the Jahn-Teller distortion and alleviates the severe phase transition during K+ intercalation/de-intercalation processes. In addition, the Co element contributes to K+ diffusion, while Al stabilizes the layer structure through strong Al-O bonds. As a result, the K0.45Mn0.7Co0.2Al0.1O2 cathode exhibits high capacities of 111 mAh g−1 and 81 mAh g−1 at 0.05 A g−1 and 1 A g−1, respectively. It also demonstrates a capacity retention of 71.6% after 500 cycles at 1 A g−1. Compared to the pristine K0.45MnO2, the K0.45Mn0.7Co0.2Al0.1O2 significantly alleviates severe phase transition, providing a more stable and effective pathway for K+ transport, as investigated by in situ X-ray diffraction. The synergistic effect of Co/Al co-substitution significantly enhances the structural stability and electrochemical performance, contributing to the development of new Mn-based cathode materials for PIBs. [ABSTRACT FROM AUTHOR]

Electrical conductivity is one of the most important concerns in spinel-structured antioxidant films coated on a solid oxide fuel cell separator, and the mechanism of electrical conduction involves the small polaron hopping through corner-shared octahedral sites. Arranging favorable ions in the octahedral sites rather than in the tetrahedral sites is better for achieving higher electrical conduction. In this study, Zn, which prefers the tetrahedral site, was substituted for the Mn 1.5 Co 1.5 O 4 spinel to arrange site distribution. The crystal structure, electrical conductivity, and thermal expansion behavior of Zn-substituted ZMCOs [Zn x Mn 1.5−0.5x Co 1.5−0.5x O 4 (0.0 ≤ x ≤ 0.6)] were investigated. At Zn = 0.2, the highest electrical conductivity of 42.1 S/cm was observed, while at Zn > 0.2, the electrical conductivity decreased due to decreased Co2+/CoIII and Mn3+/Mn4+ pair concentration because Zn ions started to occupy the octahedral site. The higher the Zn concentration of ZMCO, the lower the distortion of the MnO 6 octahedron via the Jahn–Teller effect, resulting in a higher symmetry of the crystal structure. Therefore, with the increase in the Zn concentration, a mixture of tetragonal-cubic phase changed to cubic phase. In addition, the phase transition temperature of the tetragonal-cubic phase decreased. [ABSTRACT FROM AUTHOR]

Using DFT-based molecular dynamics simulation of Cu+ cations flipping and In3+ cations displacive dynamics, we clarify the dipole ordering of CuInP2S6 ferrielectrics through the second order Jahn-Teller effect which determines the double-well potential for copper cations as well as three-well potential for indium cations inside the structural layers. The temperature dependence of the spatial distribution of Cu+ and In3+ cations is also described within the quantum anharmonic oscillator model. In3+ cations play a decisive role in the character of the polar ordering: at ambient or for positive pressures, the first order transition occurs; with the rise of negative compression, the ferrielectric transition evolves to the second order. The peculiarities of spontaneous polarization switching are related to the contributions of copper and indium cationic sublattices. [ABSTRACT FROM AUTHOR]

Regulation of the equilibrium of ion exchange processes on inorganic sorbents refers to the control of the sorption capacity and selectivity of the sorbent by regulating equilibrium conditions such as temperature, pH, concentration of sorbate, and other competing ions. By controlling these factors, it is possible to control the sorption of ions on inorganic ion exchangers for various applications, such as water purification, chemical separation, and the separation of individual ions from natural or process solutions. The ion exchange isotherm is the equation that describes the equilibrium of the ion exchange process during the absorption (sorption) or release (desorption) of specific ions from an aqueous solution. It determines the equilibrium of the ion exchange process, both sorption and desorption, connecting the amount of transfer of a substance from the aqueous medium to the solid phase at constant pressure, temperature, pH, and other external and internal conditions. This article discusses three methods for reversing ion exchange processes on inorganic sorbents. The first of them is based on a change in the charge of the sorbent matrix, the second on the use of complexing agents, and the third on displacement and equilibrium through the use of salts of weak acids or weak bases. The influence of the buffer properties of a solution on the equilibrium of ion exchange on inorganic sorbents was studied. Based on these ideas, methods have been developed to regulate the equilibrium of sorption processes on inorganic sorbents based on the binding of one of the ions participating in the sorption process into a weakly dissociating compound and changing the charge of the sorbent matrix. An essential factor in the operation of inorganic ion exchange sorbents is the potential for chemical destruction of inorganic sorbents under the influence of external and internal factors. The most radical measures to reduce these losses can be taken when selecting the starting compound for the sorbent manufacture and at the chemical synthesis stage. These factors are considered using the example of lithium-selective sorbents based on manganese oxide, which exhibits structural and external aspects of chemical instability. Their example shows the possibility of controlling the properties of such sorbents from the point of view of their chemical stability. The influence of the Jahn-Teller effect on the chemical stability of inorganic ion-exchange sorbents based on manganese oxide compounds selective for lithium ions was determined. Based on these studies, methods were proposed and tested to ensure the multi-cycle operation of highly selective inorganic ion exchange materials. [ABSTRACT FROM AUTHOR]

Excited-states play a crucial role in the optical absorption and luminescence of solids and hence their accurate information is highly desired. Herein, we attempt to seize the excited-states information of Mn4+ ions in K2SiF6 microcrystals via measuring and calculating their variable-temperature photoluminescence excitation (PLE) spectra. At cryogenic temperatures, an unpredicted splitting of the high-excited-state is observed. Moreover, the two-split high-excited-state levels are further revealed to primarily couple with the two hyperfine split modes of quasi-localized v2 vibration in the distorted Mn-F6 octahedral configuration, whereas the coupling strengths are found to be substantially different from each other. The slightly split vibrational mode is firmly supported by the low-temperature Raman spectra. Jahn-Teller lattice distortion is believed to be responsible for the observed splitting of the electronic high-excited-state and the quasi-localized vibrational mode. [ABSTRACT FROM AUTHOR]

Using DFT-based molecular dynamics simulation of Cu+ cations flipping and In3+ cations displacive dynamics, we clarify the dipole ordering of CuInP2S6 ferrielectrics through the second order Jahn-Teller effect which determines the double-well potential for copper cations as well as three-well potential for indium cations inside the structural layers. The temperature dependence of the spatial distribution of Cu+ and In3+ cations is also described within the quantum anharmonic oscillator model. In3+ cations play a decisive role in the character of the polar ordering: at ambient or for positive pressures, the first order transition occurs; with the rise of negative compression, the ferrielectric transition evolves to the second order. The peculiarities of spontaneous polarization switching are related to the contributions of copper and indium cationic sublattices. [ABSTRACT FROM AUTHOR]

Mn-based layered oxides with high theoretical capacity are one of the most promising cathode materials for potassium-ion batteries. However, the Jahn-teller distortion of Mn3+ in Mn-based layered cathodes always brings about harmful disordered structure and irreversible phase transition, resulting in severe degradation of electrochemical performance. Herein, we synthesized P3–K 0.5 Mn 0.6 Ni 0.2 M 0.2 O 2 (M = Fe, Co, FeCo) and systematically investigate the effect of component regulation on the layered structure and electrochemical properties. The P3–K 0.5 Mn 0.6 Ni 0.2 Co 0.2 O 2 exhibits a discharge capacity of 73.77 mAh g−1, demonstrating an excellent capacity retention rate of 70.17 % after 120 cycles at 50 mA g−1. In-depth analysis reveals that P3–K 0.5 Mn 0.6 Ni 0.2 Co 0.2 O 2 possesses a larger K+ layer spacing, making the insertion/extraction of potassium ions become much easier. Furthermore, the introduction of Co into the transition metal layer enhances the content of Mn4+, thereby inhibiting Jahn-Teller distortion and improving structural stability. Especially, the P3–K 0.5 Mn 0.6 Ni 0.2 Co 0.2 O 2 shows a highly reversible single-phase solid solution reaction during the initial cycle, which means the detrimental phase transition of P3–O3 caused by Jahn-Teller effect is effectively suppressed. This work contributes to a better understanding of the effect of component design and regulation on the performance of the layered oxides cathode and provide insight into the design of high-performance cathode materials for potassium-ion batteries. [ABSTRACT FROM AUTHOR]

Manganese‐based phosphate cathodes are promising candidates for developing advanced sodium‐ion batteries, primarily driven by their reliable elemental abundance, low toxicity, and desirable cycling performance. However, the cooperative Jahn–Teller effect of Mn3+ will inevitably lead to structural disorder and irreversible phase transition, thus greatly harming the reversible capacity, rate, and cycling performance. Herein, a stable NASICON‐type Na3MnHf(PO4)3 cathode is demonstrated with a volume variation of 1.9% upon the process of Na+ extraction/insertion based on the robust Hf─O bond and symmetrical MnO6 octahedron. Moreover, making full use of the stepwise redox reactions of Mn2+/Mn3+/Mn4+, this cathode reveals excellent cycling stability with a capacity retention of 85.4% after 2500 cycles at 10 C. Matching with commercial hard carbon anodes, the assembled full cell keeps a capacity retention of 92.1% with the Coulombic efficiency close to 100% after 600 cycles at 1 C. The research promises opportunities for the structural amelioration of manganese‐based phosphate cathodes toward the application in high‐performance sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

A novel Ni(OH)2/MnCO3 hybrid catalyst was developed for high-performing alkaline methanol electro-oxidation, which could well overcome the shortages of inactive MnCO3 and low intrinsic Ni(OH)2 due to the good synergistic catalysis effect from the Jahn–Teller distortion effect. [ABSTRACT FROM AUTHOR]

Highlights: γ-MnO2 loaded on N-doped biomass carbon from grapefruit peel is firstly developed. The splendid cathodic properties (e.g., coulombic efficiency: ~ 100%, energy density: 553.12 Wh kg−1) are gained. The biomass strategy guaranteed via cytotoxicity test shows a clinical potential. Zn-ion storage efficiency is boosted mainly by regulating Mn–O bond and Mn domains. Developing high-performance aqueous Zn-ion batteries from sustainable biomass becomes increasingly vital for large-scale energy storage in the foreseeable future. Therefore, γ-MnO2 uniformly loaded on N-doped carbon derived from grapefruit peel is successfully fabricated in this work, and particularly the composite cathode with carbon carrier quality percentage of 20 wt% delivers the specific capacity of 391.2 mAh g−1 at 0.1 A g−1, outstanding cyclic stability of 92.17% after 3000 cycles at 5 A g−1, and remarkable energy density of 553.12 Wh kg−1 together with superior coulombic efficiency of ~ 100%. Additionally, the cathodic biosafety is further explored specifically through in vitro cell toxicity experiments, which verifies its tremendous potential in the application of clinical medicine. Besides, Zinc ion energy storage mechanism of the cathode is mainly discussed from the aspects of Jahn–Teller effect and Mn domains distribution combined with theoretical analysis and experimental data. Thus, a novel perspective of the conversion from biomass waste to biocompatible Mn-based cathode is successfully developed. [ABSTRACT FROM AUTHOR]