Ultrafast Charge-Discharge Capable and Long-Life Na3.9 Mn0.95 Zr0.05 V(PO4 )3 /C Cathode Material for Advanced Sodium-Ion Batteries.

Na4 MnV(PO4 )3 /C (NMVP) has been considered an attractive cathode for sodium-ion batteries with higher working voltage and lower cost than Na3 V2 (PO4 )3 /C. However, the poor intrinsic electronic conductivity and Jahn-Teller distortion caused by Mn3+ inhibit its practical application. In this work, the remarkable effects of Zr-substitution on prompting electronic and Na-ion conductivity and also structural stabilization are reported. The optimized Na3.9 Mn0.95 Zr0.05 V(PO4 )3 /C sample shows ultrafast charge-discharge capability with discharge capacities of 108.8, 103.1, 99.1, and 88.0 mAh g-1 at 0.2, 1, 20, and 50 C, respectively, which is the best result for cation substituted NMVP samples reported so far. This sample also shows excellent cycling stability with a capacity retention of 81.2% at 1 C after 500 cycles. XRD analyses confirm the introduction of Zr into the lattice structure which expands the lattice volume and facilitates the Na+ diffusion. First-principle calculation indicates that Zr modification reduces the band gap energy and leads to increased electronic conductivity. In situ XRD analyses confirm the same structure evolution mechanism of the Zr-modified sample as pristine NMVP, however the strong ZrO bond obviously stabilizes the structure framework that ensures long-term cycling stability.

Room-Temperature All-Solid-State Sodium Battery Based on Bulk Interfacial Superionic Conductor.

All-solid-state sodium batteries (ASSSBs) are attractive alternatives to lithium-ion batteries for grid-scale energy storage due to their high safety and ubiquitous distribution of Na sources. A critical component for ASSSB is sodium-ion conducting solid-state electrolyte (SSE). Here, we report a high-performance sodium-ion SSE with the recently developed bulk interfacial superionic conductor (BISC) concept. The ionic conductivity and areal conductance of the Na+ BISC at 25 °C reaches 6.5 × 10-4 S cm-1 and 260 mS cm-2, respectively. Using NaxCo0.7Mn0.3O2 (x ≈ 1.0, NaCMO) as the cathode active material, all-solid-state Na||NaCMO batteries exhibiting small overpotential and ∼180 cycle life are demonstrated under room temperature. This approach may also be used to prepare other metal ion, such as Mg2+, Al3+, and K+, based all-solid-state batteries.

Surface-Stabilized High-Entropy Layered Oxyfluoride Cathode for Lithium-Ion Batteries.

High-entropy materials have been demonstrated to improve the structural stability and electrochemical performance of layered cathode materials for lithium-ion batteries (LIBs). However, structural stability at the surface and electrochemical performance of these materials are less than ideal. In this study, we show that fluorine substitution can improve both issues. Here, we report a new high-entropy layered cathode material Li1.2Ni0.15Co0.15Al0.1Fe0.15Mn0.25O1.7F0.3 (HEOF1) based on the partial substitution of oxygen with fluorine in previously reported high-entropy layered oxide LiNi0.2Co0.2Al0.2Fe0.2Mn0.2O2. This new compound delivers a discharge capacity of 85.4 mAh g-1 and a capacity retention of 71.5% after 100 cycles, showing significant improvement from LiNi0.2Co0.2Al0.2Fe0.2Mn0.2O2 (first 57 mAh g-1 and 9.8% after 50 cycles). This improved electrochemical performance is due to suppression of the surface M3O4 phase formation. Although still an early stage study, our results show an approach to stabilize the surface structure and improve the electrochemical performance of high-entropy layered cathode materials.

Surface Phase Conversion in a High-Entropy Layered Oxide Cathode Material.

High-entropy transition-metal oxides are potentially interesting cathode materials for lithium-ion batteries, among which high-entropy layered oxides are considered highly promising because there exist two-dimensional ion transport channels that may, in principle, enable fast ion transport. However, high-entropy layered oxides reported to date exhibit fast capacity fading in initial cycles and thus are hardly of any practical value. Here, we investigate the structural and property changes of a five-element layered oxide, LiNi0.2Co0.2Mn0.2Fe0.2Al0.2O2, using electrochemical and physical characterization techniques. It is revealed that the M3O4 phase formed at the surface of LiNi0.2Co0.2Mn0.2Fe0.2Al0.2O2 due to the migration of metal ions from octahedral sites of the transition-metal layer to tetrahedral 8a and octahedral sites of the lithium layer hinders the intercalation of lithium ion, which leads to the low initial Coulombic efficiency and fast decay of reversible capacity. This mechanism could be generally applicable to other high-entropy layered oxides with different elemental compositions.

A High-Rate, Durable Cathode for Sodium-Ion Batteries: Sb-Doped O3-Type Ni/Mn-Based Layered Oxides.

O3-Type layered oxides are widely studied as cathodes for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, their rate capability and durability are limited by tortuous Na+ diffusion channels and complicated phase evolution during Na+ extraction/insertion. Here we report our findings in unravelling the mechanism for dramatically enhancing the stability and rate capability of O3-NaNi0.5Mn0.5-xSbxO2 (NaNMS) by substitutional Sb doping, which can alter the coordination environment and chemical bonds of the transition metal (TM) ions in the structure, resulting in a more stable structure with wider Na+ transport channels. Furthermore, NaNMS nanoparticles are obtained by surface energy regulation during grain growth. The synergistic effect of Sb doping and nanostructuring greatly reduces the ionic migration energy barrier while increasing the reversibility of the structural evolution during repeated Na+ extraction/insertion. An optimized NaNMS-1 electrode delivers a reversible capacity of 212.3 mAh g-1 at 0.2 C and 74.5 mAh g-1 at 50 C with minimal capacity loss after 100 cycles at a low temperature of -20 °C. Such electrochemical performance is superior to most of the reported layered oxide cathodes used in rechargeable SIBs.

Stabilizing a High-Voltage Lithium-Rich Layered Oxide Cathode with a Novel Electrolyte Additive.

We report a novel electrolyte additive, bis(trimethylsilyl)carbodiimide, that effectively stabilizes high-voltage lithium-rich oxide cathode. Charge/discharge tests demonstrate that even trace amounts of bis(trimethylsilyl)carbodiimide in a baseline electrolyte improve the cycling stability of this cathode significantly, either in Li-based half cells or graphite-based full cells, where the capacity retention after 200 cycles between 2 and 4.8 V at 0.5C is enhanced from 40 to 72% and 49 to 77%, respectively. Analyses using physical characterization and theoretical calculations reveal that this additive not only builds a protective film on the cathode but also eliminates detrimental hydrogen fluoride via its strong coordination with hydrogen fluoride or protons.

N-Allyl- N, N-Bis(trimethylsilyl)amine as a Novel Electrolyte Additive To Enhance the Interfacial Stability of a Ni-Rich Electrode for Lithium-Ion Batteries.

Enhancing the electrode/electrolyte interface stability of high-capacity LiNi0.8Co0.15Al0.05O2 (LNCA) cathode material is urgently required for its application in next-generation lithium-ion battery. Herein, we demonstrate that enhanced interfacial stability of LNCA can be achieved by simply introducing 2 wt % N-allyl- N, N-bis(trimethylsilyl)amine (NNB) electrolyte additive. Electrolyte oxidation reactions and electrode structural destruction are greatly suppressed in the electrolyte with NNB additive, leading to improved cyclic stability of LNCA from 72.8 to 86.2% after 300 cycles. The mechanism of NNB on improving the cyclic stability of LNCA has been verified to its excellent solid electrolyte interface (SEI) film-forming capability. Moreover, the X-ray diffraction and X-ray photoelectron spectroscopy results indicate that the NNB-derived Si-containing SEI film restrains the Li/Ni disorder of LNCA during cycling, which further improves the cyclic stability of Ni-rich LNCA. Importantly, the charging/discharging test reveals that the NNB additive effectively improves the cyclic stability of the LNCA/graphite full cell.

Testicular orphan receptor 4 (TR4) is a marker for metastasis and poor prognosis in non-small cell lung cancer that drives the EMT phenotype.

OBJECTIVES: Aberrant expression of testicular orphan receptor 4 (TR4) has been shown to regulate biological processes near solid tumors. However, the role of TR4 in non-small cell lung cancer (NSCLC) patient prognosis and the development of NSCLC cancer cells are unclear. METHODS: Immunohistochemical analysis was used to evaluate the correlation between TR4 expression and clinicopathological characteristics in 291 cases of NSCLC specimens. A knockdown and overexpression of TR4 was performed to assess the role of TR4. Transwell and colony formation assays were completed to investigate the metastatic and proliferative abilities. Quantitative real-time PCR, Western blotting and immunofluorescence staining were carried out to analyze the epithelial-to-mesenchymal transition (EMT) phenotype. RESULTS: Immunohistochemical evaluation of clinical samples revealed that most of the lung cancer tissues were strongly positive for TR4, whereas the tissues that stained weakly positive or negative for TR4 expression were shown in the paired normal tissues. Moreover, higher levels of TR4 expression were significantly associated with higher lymph node metastases, TNM stages, tumor thrombus in vena and poor prognosis. We observed that downregulation and up-regulation of TR4 with stable cell transfection significantly influence the proliferation, invasive and metastatic abilities of NSCLC lines. In addition, aberrant TR4 expression could modulate the expression levels of several EMT related markers. CONCLUSIONS: Collectively, our results show TR4 expression in NSCLC samples is significantly associated with poor clinicopathological features, and TR4 plays an important role in the metastatic capacity of NSCLC cells by EMT regulation.