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The electrochemical activity and stability of Li2MnO3 are affected synchronously by lattice vacancies and local coordination configuration.

To ensure clinical efficacy and prolong patient survival, treatments such as surgery and microwave ablation (MWA) are used for early liver cancer. MWA is preferred because it effectively preserves the normal liver tissue and causes transient coagulation necrosis of local liver tumor cells. However, due to technical limitations, the cancerous liver tissue cannot be completely ablated; therefore, the probability of local tumor recurrence is high.To investigate the clinical efficacy and safety of ultrasound-guided percutaneous MWA in the treatment of small liver cancer.A total of 118 patients treated for small liver cancer in The Central Hospital of Yongzhou from January 2018 to April 2019 were selected. Sixty-six patients received ultrasound-guided percutaneous MWA (MWA group) and 52 received laparoscopic surgery (laparoscope group). The operation time, blood loss, hospital stay, and medical expenses of both groups were statistically analyzed. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), albumin (ALB), alpha fetal protein (AFP), carcinoembryonic antigen (CEA), and peripheral blood regulatory T lymphocytes (Treg) levels were evaluated pre- and post-operatively. The cross-sectional area of tumors measured before and after ablation was analyzed statistically; the therapeutic effect was compared between both groups in terms of surgical complications, 2-year progression-free survival rate, and overall survival rate.The operation time, blood loss, hospital stay, and medical expenses in the MWA group were lower than those of the laparoscope group, and the differences were significant (The effects of ultrasound-guided percutaneous MWA in the treatment of small liver cancer are similar to those of laparoscopic surgery. However, ablation causes less trauma and liver dysfunction.

Traditional O3-type Li-rich layered materials are attractive with ultra-high specific capacities, but suffering from inherent problems of voltage hysteresis and poor cycle performance. As an alternative, O2-type materials show the potential to improve the oxygen redox reversibility and structural stability. However, their structure-performance relationship is still unclear. Here, we investigate the correlation between the Li component and dynamic chemical reversibility of O2-type Li-rich materials. By exploring the formation mechanism of a series of materials prepared by Na/Li exchange, we reveal that insufficient Li leads to an incomplete replacement, and the residual Na in the Li-layer would hinder the fast diffusion of Li+. Moreover, excessive Li induces the extraction of interlayer Li during the melting chemical reaction stage, resulting in a reduction in the valence of Mn, which leads to a severe Jahn-Teller effect. Structural detection confirms that the regulation of Li can improve the cycle stability of Li-rich materials and suppress the trend of voltage fading. The reversible phase evolution observed in in-situ X-ray diffraction confirms the excellent structural stability of the optimized material, which is conducive to capacity retention. This work highlights the significance of modulating dynamic electrochemical performance through the intrinsic structure.

Various properties of sodium ion batteries deteriorate severely when dropping to subzero temperature. Herein, we reveal an accelerated charge-transfer mechanism for high-voltage Na3V2(PO4)2F3 cathode through constructing weakly-solvating architecture, which endows it with superior temperature adaptability (capacity retention of C − 25 ∘ C / C 25 ∘ C reaches 90.8%). The resulting weak solvation effects synergistically lower the activation energy barrier for charge-transfer reactions, thus accelerating the kinetics at low temperature and increasing the energy density by ∼75 Wh Kg−1. Ab initio molecular dynamics calculations show that a weakly-solvating structure forms spontaneously in a low-concentration electrolyte (merely 0.3 M) and thereby facilitates Na+ desolvation process. Besides, visual TOF-SIMS confirms the construction of a dense and uniform cathode/electrolyte interface layer, which optimizes the interface chemistry and improves the interfacial kinetics. In-situ and ex-situ XRD also evidence a smaller degree of structural evolution of the Na3V2(PO4)2F3 cathode, which contributes to long-term durability (attaining a high capacity retention of 93.4% after 1000 cycles at −25 °C). Furthermore, it is demonstrated that under such extreme conditions the Na3V2(PO4)2F3||hard-carbon full cell functions well for over 300 h. These findings elucidate the roles of weak solvation construction in realizing faster kinetics for high-voltage cathodes and provide a feasible pathway for achieving more practical sodium ion batteries.

As the candidate cathode material of next-generation lithium-ion batteries (LIBs), Li-rich layered oxides (LLOs) suffer from the problems of surface residual lithium and own insufficient performance as an ionic and electronic conductor. Herein, we propose a strategy for in situ utilization of the residual lithium to form a functionalized sulfur-containing surface coating layer for Co-free LLOs by designated consumption of the residual lithium compounds (Li2CO3 and LiOH) with a simple sulfur treatment. The layer significantly improves the lithium-ion diffusion kinetics at high current rates and inhibits the growth of charge transfer resistance. The results of composition and structure characterization prove that the layer mainly containing Li2SO4 guides the favorable evolution of particles’ bulk crystal structure during the cycle. The modified sample exhibits a higher first coulombic efficiency of 84.4%, excellent rate capabilities, and superior cycle capacity retention of 93.3% after 300 cycles at 250 mA g−1.

Sluggish kinetics and limited reversible capacity present two major challenges for layered titanates to achieve satisfactory sodium-ion storage performance at subzero-temperatures (subzero-T). To f...

Anion doping is considered as an effective method to tap the potential of Li-rich materials to obtain more discharge capacity. Here, we prepare fluorine-doped Li1.2Ni0.2Mn0.6O2 materials by a low-temperature secondary sintering. Rietveld refinements of XRD show an increase in lattice parameters and indicate a wider Li+ diffusion channel after fluorine doping. From TEM and HRTEM images, it is observed that the fluorine-doped sample displays a more pronounced layered appearance, and partial lattice fringes are slightly curved which may be caused by the substitution of F for O to break the symmetry of MnO6 octahedron. The fitting results of XPS show that Mn is partially oxidized and the local electronic environment of O changes. The best one shows a discharge capacity of 288 mAh/g at 0.1 C with a Coulombic efficiency of 95.9% in the first lap. And it performs a capacity retention of 91.0% after 100 cycles at 0.2 C.

We normalize data from 43 Chinese observatories and select data from ten Chinese observatories with most continuous records to assess the secular variations (SVs) and geomagnetic jerks by calculating the deviations between annual observed and CHAOS-6 model monthly means. The variations in the north, east, and vertical eigendirections are studied by using the covariance matrix of the residuals, and we find that the vertical direction is strongly affected by magnetospheric ring currents. To obtain noise-free data, we rely on the covariance matrix of the residuals to remove the noise contributions from the largest eigenvalue or vectors owing to ring currents. Finally, we compare the data from the ten Chinese observatories to seven European observatories. Clearly, the covariance matrix method can simulate the SVs of Dst, the jerk of the northward component in 2014 and that of the eastward component in 2003.5 in China are highly agree with that of Vertically downward component in Europe, compare to CHAOS-6, covariance matrix method can show more details of SVs.

Sluggish kinetics and limited reversible capacity present two major challenges for layered titanates to achieve satisfactory sodium-ion storage performance at subzero-temperatures (subzero-T). To facilitate sodiation dynamics and improve reversible capacity, we proposed an additive-free anode with Sn(II) located between layers. Sn-5s in interlayer-confining Sn(II), which has a larger negative charge, will hybridize with O-2p to trigger charge redistribution, thereby enhancing electronic conductivity. H-titanates with an open framework are designed to stabilize Sn(II) and restrain subsequent volume expansion, which could potentially surpass the capacity limitation of titanate-based materials via a joint alloying-intercalation reaction with high reversibility. Moreover, the generation of conductive Na

Due to the sluggish interfacial kinetics, the energy density and cycle life of sodium-ion batteries (SIBs) suffer severely at subzero temperatures. Herein, to accelerate the interfacial charge transfer process and improve the low-temperature SIBs performance, a strategy by triggering Na+-solvent co-intercalation is proposed. Using hydrogen titanate nanowires (HT-NW) as a model, we found that the layer structure regulation with oxygen defects could trigger HT-NW presents a unique Na+-solvent co-intercalation behavior in the ether-based electrolyte at −25 °C according to ex-situ FTIR and XRD. By eliminating the Na+ desolvation process, Na+-solvent co-intercalation could effectively accelerate the Na+ diffusion kinetics and reduce the activation energy to 66.0 meV. Benefit from these ameliorations, the defective HT-NW delivers a high capacity of 238 mAh g−1 at −25 °C, which is equivalent to 89% of that at 25 °C. Besides, the defective HT-NW shows great superiority in cycle stability, maintaining capacity retention of 80.6% after 4200 cycles at 1.0 A g−1 at −25 °C. Moreover, at −25 °C, the defective HT-NW//Na3V2(PO4)3 full cell exhibits high energy density (119.1 Wh kg−1) and outstanding stability (94.5% after 1000 cycles at 1.0C). These findings reveal that the ion–solvent co-intercalation is highly feasible to improve the battery performance at low temperatures by accelerating charge transfer kinetics.

Spinel LiNi0.5Mn1.5O4 (LNMO) is widely utilized because of its high-energy-density and high-voltage. Unfortunately, there is still much research to be done for LNMO due to its poor structural stability. Here, a strategy is confirmed to stabilize LNMO via modulating interstitial sites. The interstitial 16c sites of the octahedron are partially occupied by Ni2+ to suppress the migration and dissolution of manganese ions upon electrochemical cycling and stabilize lithium-ion vacancies in the state of charge. Unexpectedly, this protocol not only suppresses the phase separation restraining the phase boundary dislocations and stress but also decreases the magnitude of cell volume change during cycling, which originates from the change in Ni redox couple energy states. This two-pronged modification strategy endows the cathode material with a lower charge transfer barrier and faster Li+ transfer kinetics, revealing superior electrochemical performance. The regulated cathode material remains robust after 900 cycles at 1 C and its capacity retention rate is 29% higher than that of the original sample. Our research is useful for providing a concrete example of how the electrochemical performance of spinel LNMO and other high voltage cathode materials can be enhanced.

Compared with Li-ions, it is difficult to achieve fast dynamics for Na/K-ion storage. H-titanates as potential candidates suffer from low theoretical capacity, limiting the energy density of full cells. Herein, we report an Sn(Ⅱ)/Sn(Ⅳ) gradient doping strategy to simultaneously realizes the construction of a disordered interface with abundant defects and well-organized interlayered structure with larger interlayer spacing in H-titanate. The interfacial-located Sn2+ with a larger ionic radius triggers surface structural distortion to realize a favorable electronic structure with a narrower bandgap. Meanwhile, the interlayer-located Sn4+ plays a pillar effect to enhance the structural stability and modify the interlayer ion transport channel. Based on the analysis of ex-situ XRD, time of flight secondary ion mass spectrometry and temperature-dependent EIS, it is found that Sn(Ⅱ)/Sn(Ⅳ) gradient doping can effectively enhance structural stability, lower charge transfers barrier and boost ion diffusion kinetics, then resulting in 2.4- and 1.5-fold improvement for Li-ion and Na-ion storage, high capacity of 223 mAh g−1 and long cycle stability over 1800 cycles for K-ion storage. When used as additive-free anodes for hybrid capacitors, impressive energy densities in Li/Na-ion systems and superior cycle stability in Na/K-ion configurations have been achieved. These findings indicating that Sn(Ⅱ)/Sn(Ⅳ) gradient doping strategy has significant advantages for fast and durable alkali-ion storage.

Na3V2(PO4)2F3 is a promising cathode candidate for sodium ion batteries due to its high working voltage. However, an “unknown” low-voltage plateau around ~3.3 V lowers its operating voltage and puzzles researchers. Herein, the reasons for its appearance are explored. It is found that the formation of the low-voltage plateau originates from the extra-generated [VO6] induced by the fluorine loss during the synthesis. To enable better performance, a feasible strategy of stabilizing fluorine is proposed to eliminate the low-voltage plateau. It is demonstrated that this strategy can effectively guarantee the existence of fluorine and modulate the local electronic structure of V to maintain [VO4F2] in Na3V2(PO4)2F3 phase, thus eliminating the undesirable plateau and achieving an operating-voltage increase of ~100 mV. Moreover, the enhanced structural stability and kinetics of the optimized Na3V2(PO4)2F3 cathode are confirmed by in-situ XRD. As expected, the Na3V2(PO4)2F3 cathode delivers higher energy density (446.4 Wh kg−1), better rate capability and longer cycling performance (89.2%@30 C after 1000 cycles). Furthermore, its excellent adaptability to wide temperature range (−25 °C–55 °C) and strong competence in Na3V2(PO4)2F3||hard carbon full-cell are verified. These excellent properties further qualify Na3V2(PO4)2F3 as a competitive cathode for sodium ion batteries.

Ti-based oxides have attracted extensive attention as promising lithium-intercalated materials for hybrid capacitors. However, the low electronic conductivity and sluggish lithiation dynamics hinder their performance including reversible capacity, rate capability, and cycle stability. Herein, we report a kind of quasi-layered titanate hydrates (Q-TH) deriving from the dehydration-induced structural rearrangement of Ti-O octahedra and their superior electrochemical performance in the quasi-solid-state Li-ion capacitors. As predicted by Mulliken charge analysis, the surrounding O atoms will transfer electrons to the central Ti atoms accompanying with the detachment of bonding -OH groups. The resulting unpaired 3d electron would be injected into the t2g* antibonding orbital, deflecting the conduction band to the Fermi level and introducing intermediate bands within the bandgap, thereby enhancing the electronic conductivity of Q-TH. Such a special electronic structure will reduce polarization, facilitate fast Li-ion diffusion and lower the activation barrier (0.309 eV). Hence, impressive energy densities (116 Wh kg−1) and competitive cycling ability (86%, 3000 cycles) can be achieved when used as additive-free anodes in quasi-solid-state LICs with graphene nanosheets (GNS) cathodes. Thus, dehydration could be an effective way to modulate the electronic structure of titanate hydrates instead of just an approach to removing water.

Lithium-rich materials, which exhibit high capacity due to the existence of anionic redox, are in highly demanded for high energy density Li ion batteries. Nevertheless, the low operating voltage and rapid voltage drop of Li-Rich cathodes are seen as the fatal issues, which result in reduced energy density and degraded energy quality of the batteries, limiting their further commercial application. Herein, we focus on the local electronic structure controlled by chemical composition (to prepared high Ni content Li-rich cathode) to improve the operating voltage and suppress voltage decay. Through detailed physical characterization, electrochemical analysis and theoretical calculations, we summarize three main factors for improving the voltage of lithium-rich materials: 1) Increasing the O-Ni2+/3+/Li+ content effectively regulates the coordination environment of oxygen in Li-rich materials, realizes the regulation of local electronic structure; 2) the substitution of Ni increases the oxidation state of TM ions, especially for Mn, to keep charge balance, so as to improve the operating voltage and suppress voltage decay; 3) adjusting local electronic structure shifts the TM 3d-O 2p bands and the non-bonding O 2p band to lower energy, leading to an increase in the redox reaction potential. This strategy provides a method to regulate the coupling reaction of cation and anion redox in Li-rich cathodes by compositional design, so as to realize the regulation of voltage. Furthermore, when the as-prepared high Ni content electrode assembled with Si/C anode into a full-cell, impressive operating voltage (~3.70 V) and long cycle life (72.29% capacity retention after 200 cycles at 1C) can be achieved. Our work provides an efficient and up-scalable strategy for the preparation of electrodes with high voltage and high useful energy density, and making them a rather promising cathode candidate for Li ion batteries.