Conductive Robust Interfaces with Fluoro-Borate Based Electrolyte Additive for 4.6 V Well-Cycled LiNi0.90Co0.06Mn0.04O2||Li Batteries.

Owing to the outstanding comprehensive properties of high energy density, excellent cycling ability, and reasonable cost, Ni-rich layered oxides (NCM) are the most promising cathode for lithium-ion batteries (LIBs). To further enhance the specific capacity of Ni-rich layered oxides, it is necessary to increase the cut-off voltage to a higher level. However, a higher cut-off voltage can lead to substantial structural changes and trigger interface side reactions, presenting significant challenges for practical applications (cycle life and safety). Herein, to solve above issues, tris(hexafluoroisopropyl)borate (TFPB) is introduced as a high voltage electrolyte additive for LiNi0.90Co0.06Mn0.04O2 cathode. Based on detail in situ/ex situ characterization, this study proves that TFPB forms a protective solid-state interphase (SEI) layer on the Li-anode. Additionally, derivatives of TFPB are easily oxidatively decomposed to create a dense cathode electrolyte interphase (CEI) film on the cathode. This CEI film effectively prevents the continuous oxidation of the electrolyte and mitigates the adverse effects of HF on the battery. Benefit from the protective SEI and CEI layer, the LiNi0.90Co0.06Mn0.04O2||Li battery with a TFPB-containing electrolyte maintains an unprecedented level of performance, with a capacity retention of 89.1% after 100 cycles under the ultrahigh cut-off voltage of 4.6 V (vs Li/Li+).

Engineering Crystal Growth and Surface Modification of Na3 V2 (PO4 )2 F3 Cathode for High-Energy-Density Sodium-Ion Batteries.

Na3 V2 (PO4 )2 F3 (NVPF) is a suitable cathode for sodium-ion batteries owing to its stable structure. However, the large radius of Na+ restricts diffusion kinetics during charging and discharging. Thus, in this study, a phosphomolybdic acid (PMA)-assisted hydrothermal method is proposed. In the hydrothermal process, the NVPF morphologies vary from bulk to cuboid with varying PMA contents. The optimal channel for accelerated Na+ transmission is obtained by cuboid NVPF. With nitrogen-doping of carbon, the conductivity of NVPF is further enhanced. Combined with crystal growth engineering and surface modification, the optimal nitrogen-doped carbon-covered NVPF cuboid (c-NVPF@NC) exhibits a high initial discharge capacity of 121 mAh g-1 at 0.2 C. Coupled with a commercial hard carbon (CHC) anode, the c-NVPF@NC||CHC full battery delivers 118 mAh g-1 at 0.2 C, thereby achieving a high energy density of 450 Wh kg-1 . Therefore, this work provides a novel strategy for boosting electrochemical performance by crystal growth engineering and surface modification.

Differentiation of benign versus malignant indistinguishable vertebral compression fractures by different machine learning with MRI-based radiomic features.

OBJECTIVES: To explore an optimal machine learning (ML) model trained on MRI-based radiomic features to differentiate benign from malignant indistinguishable vertebral compression fractures (VCFs). METHODS: This retrospective study included patients within 6 weeks of back pain (non-traumatic) who underwent MRI and were diagnosed with benign and malignant indistinguishable VCFs. The two cohorts were retrospectively recruited from the Affiliated Hospital of Qingdao University (QUH) and Qinghai Red Cross Hospital (QRCH). Three hundred seventy-six participants from QUH were divided into the training (n = 263) and validation (n = 113) cohort based on the date of MRI examination. One hundred three participants from QRCH were used to evaluate the external generalizability of our prediction models. A total of 1045 radiomic features were extracted from each region of interest (ROI) and used to establish the models. The prediction models were established based on 7 different classifiers. RESULTS: These models showed favorable efficacy in differentiating benign from malignant indistinguishable VCFs. However, our Gaussian naïve Bayes (GNB) model attained higher AUC and accuracy (0.86, 87.61%) than the other classifiers in validation cohort. It also remains the high accuracy and sensitivity for the external test cohort. CONCLUSIONS: Our GNB model performed better than the other models in the present study, suggesting that it may be more useful for differentiating indistinguishable benign form malignant VCFs. KEY POINTS: • The differential diagnosis of benign and malignant indistinguishable VCFs based on MRI is rather difficult for spine surgeons or radiologists. • Our ML models facilitate the differential diagnosis of benign and malignant indistinguishable VCFs with improved diagnostic efficacy. • Our GNB model had the high accuracy and sensitivity for clinical application.

Cross-Linked Sodium Alginate-Sodium Borate Hybrid Binders for High-Capacity Silicon Anodes in Lithium-Ion Batteries.

Silicon is considered one of the most promising next-generation anode materials for lithium-ion batteries. It has the advantages of high theoretical specific capacity (4200 mAh·g-1), which is 10 times larger than that of a commercial graphite anode (372 mAh·g-1). However, there are some problems such as the pulverization of the electrode and an unstable solid electrolyte interphase (SEI) layer aroused by the huge bulk effect (>300%) of Si during the repeated lithiation/delithiation process. A binder plays a vital role in the conventional lithium-ion batteries that can effectively relieve the bulk expansion stress of a silicon anode. In this work, the inorganic cross-linker sodium borate (SB) and the commonly used binder sodium alginate (SA) were condensed through an esterification reaction and the reaction product was marked as SA-SB. It is found that the mechanical robustness and the peel strength of SA-SB are improved after cross-linking, which is conducive to maintaining the structural stability of the silicon anode in long cycle life. In consequence, the capacity retention of the silicon anode using the SA-SB binder (64.1%) is higher than that of SA (50.6%) after 100 cycles at 0.2 A·g-1.

A Stress Self-Adaptive Silicon/Carbon "Ordered Structures" to Suppress the Electro-Chemo-Mechanical Failure: Piezo-Electrochemistry and Piezo-Ionic Dynamics.

Construction of ordered structures that respond rapidly to environmental stimuli has fascinating possibilities for utilization in energy storage, wearable electronics, and biotechnology. Silicon/carbon (Si/C) anodes with extremely high energy densities have sparked widespread interest for lithium-ion batteries (LIBs), while their implementation is constrained via mechanical structure deterioration, continued growth of the solid electrolyte interface (SEI), and cycling instability. In this study, a piezoelectric Bi0.5 Na0.5 TiO3 (BNT) layer is facilely deposited onto Si/C@CNTs anodes to drive piezoelectric fields upon large volume expansion of Si/C@CNTs electrode materials, resulting in the modulation of interfacial Li+ kinetics during cycling and providing an electrochemical reaction with a mechanically robust and chemically stable substrate. In-depth investigations into theoretical computation, multi-scale in/ex situ characterizations, and finite element analysis reveal that the improved structural stability, suppressed volume variations, and controlled ion transportation are responsible for the improvement mechanism of BNT decorating. These discoveries provide insight into the surface coupling technique between mechanical and electric fields to control the interfacial Li+ kinetics behavior and improve structural stability for alloy-based anodes, which will also spark a great deal attention from researchers and technologists in multifunctional surface engineering for electrochemical systems.

Novel PETEA-based grafted gel polymer electrolyte with excellent high-rate cycling performance for LiNi0.5Co0.2Mn0.3O2 lithium-ion batteries.

Due to the higher specific capacity and operating voltage platform of the ternary cathode material (LiCoxNiyMn1-x-yO2), it has a specific market application in the electric vehicle (EV) industry. Gel polymer electrolytes (GPEs) have proven to be an effective method of resolving this issue. As a result of its high conductivity and safety performance, pentaerythritol tetraacrylate (PETEA) is a promising gel polymer electrolyte. Butyl methacrylate (BMA) was successfully grafted onto PETEA to decrease its stiffness in this study. Surprisingly, after cycling for 100 cycles at a rate of 2 C, the cycle retention rate of the half-cell of NCM523/GPE/Li reached 63.9%, whereas the utilization of liquid electrolyte ceased to function normally. The successfully prepared PETEA-g-BMA GPE by in-situ thermal polymerization formed a three-dimensional network structure. The PETEA-g-BMA GPE effectively protected the structure of the cathode material during the lithium-ion charging and discharging process, inhibited the occurrence of side reactions, and minimized the risk of thermal runaway. The straightforward preparation process and low cost make industrial applications a possibility in the future.

Interface-Driven Pseudocapacitance Endowing Sandwiched CoSe2/N-Doped Carbon/TiO2 Microcubes with Ultra-Stable Sodium Storage and Long-Term Cycling Stability.

Cobalt diselenide (CoSe2) has drawn great concern as an anode material for sodium-ion batteries due to its considerable theoretical capacity. Nevertheless, the poor cycling stability and rate performance still impede its practical implantation. Here, CoSe2/nitrogen-doped carbon-skeleton hybrid microcubes with a TiO2 layer (denoted as TNC-CoSe2) are favorably prepared via a facile template-engaged strategy, in which a TiO2-coated Prussian blue analogue of Co3[Co(CN)6]2 is used as a new precursor accompanied with a selenization procedure. Such structures can concurrently boost ion and electron diffusion kinetics and inhibit the structural degradation during cycling through the close contact between the TiO2 layer and NC-CoSe2. Besides, this hybrid structure promotes the superior Na-ion intercalation pseudocapacitance due to the well-designed interfaces. The as-prepared TNC-CoSe2 microcubes exhibit a superior cycling capability (511 mA h g-1 at 0.2 A g-1 after 200 cycles) and long cycling life (456 mA h g-1 at 6.4 A g-1 for 6000 cycles with a retention of 92.7%). Coupled with a sodium vanadium fluorophosphate (Na3V2(PO4)2F3)@C cathode, this assembled full cell displays a specific capacity of 281 mA h g-1 at 0.2 A g-1 for 100 cycles. This work can be potentially used to improve other metal selenide-based anodes for rechargeable batteries.