Manipulating the diffusion energy barrier at the lithium metal electrolyte interface for dendrite-free long-life batteries.

Constructing an artificial solid electrolyte interphase (SEI) on lithium metal electrodes is a promising approach to address the rampant growth of dangerous lithium morphologies (dendritic and dead Li0) and low Coulombic efficiency that plague development of lithium metal batteries, but how Li+ transport behavior in the SEI is coupled with mechanical properties remains unknown. We demonstrate here a facile and scalable solution-processed approach to form a Li3N-rich SEI with a phase-pure crystalline structure that minimizes the diffusion energy barrier of Li+ across the SEI. Compared with a polycrystalline Li3N SEI obtained from conventional practice, the phase-pure/single crystalline Li3N-rich SEI constitutes an interphase of high mechanical strength and low Li+ diffusion barrier. We elucidate the correlation among Li+ transference number, diffusion behavior, concentration gradient, and the stability of the lithium metal electrode by integrating phase field simulations with experiments. We demonstrate improved reversibility and charge/discharge cycling behaviors for both symmetric cells and full lithium-metal batteries constructed with this Li3N-rich SEI. These studies may cast new insight into the design and engineering of an ideal artificial SEI for stable and high-performance lithium metal batteries.

Electrochemically Prepared Polyaniline as an Alternative to Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) for Inverted Perovskite Solar Cells.

The goal of this work is to substitute the conventional high-cost poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) in inverted perovskite solar cells (PSCs) with an efficient and conducting polyaniline (PANI) polymer. The reported use of PANI in PSCs involves a chemical synthesis method which is prone to contamination with impurities as it requires several materials for polymerization and adhesion improvement with substrates, contributing to low device efficiencies. This work mitigates this issue using an electrochemical method that is low cost, less time consuming, and capable of producing thin films of PANI with excellent adhesion to substrates. Results demonstrated that the power conversion efficiency of the electrochemically synthesized PANI-based PSC is 16.94% versus 15.11% for the PEDOT:PSS-based device. It was observed that the work function of PANI was lower compared to that of PEDOT:PSS which decreased V OC but enhanced hole extraction at the hole transport layer/perovskite interface, thus increasing J SC. Doping electrolyte solution with lithium bis(trifluoromethanesulfonyl)imide LiTFSI increased the work function of PANI, thus increasing V OC from 0.87 to 0.93 V. This method enables simple and scalable synthesis of PANI as a competitive hole transport material to replace rather expensive PEDOT:PSS, thus enabling an important step toward low-cost inverted perovskite photovoltaic devices.

Intraspinal periosteal chondroma in upper thoracic spine causing cord compression and myelopathy: A case report.

INTRODUCTION: Chondromas are slow-growing cartilage-forming benign tumors, rarely occurring in the spine. Generally, most spinal chondromas are asymptomatic; however, with slow progressive growth, these lesions may enlarge and expand and cause compressive neurological symptoms, resulting in radiculopathy or more commonly myelopathy due to direct neural compression. PRESENTATION OF CASE: A 15-year-old male adolescent presented to Emergency Department with history of fall (slippage) on concrete ground while playing three months back. On neurological examination, the motor power in bilateral upper limbs was 5/5 while it was 1/5 in both lower extremities. Some muscle wasting was noted in the lower limbs. The planter reflexes were upgoing; and the sensory loss was below T6 spinal level. CT scan of dorsolumbar spine demonstrated a well-defined high-density lesion in lateral aspect of spinal canal at T2-T3 vertebral level adjacent to left T2-T3 facet joint. MRI of dorsal spine revealed a 3 × 2 × 1 cm3-sized, well-defined, non-enhancing T1 low to isointense and T2/STIR heterogeneous hyperintense lesion with osseous and cartilaginous components in the left lateral aspect of spinal canal at T1-T3 level, causing compression and contralateral displacement of spinal cord. The patient was then subjected to posterior laminectomy, complete excision, followed by laminoplasty using minicranial plates and screws. Histopathology of the mass showed bony trabeculae with hematopoietic elements and attached lobules of hyaline cartilage, chondroid matrix and lobules of mature chondrocyte and myxoid changes. Postoperatively his power was improved slightly and he was able to stand up with some assistance. On six-month follow up, patient showed significant neurological improvement. He was able to walk independently with minimal assistance. He was able to control bowel and bladder functions. DISCUSSION: Chondromas occurring in the spine are rare, accounting for only about 3% of all chondromas. Spinal chondromas are commonly encountered in the thoracic spine as in our case. CONCLUSION: Complete en bloc surgical excision is generally recommended as the treatment of choice for cases with local and/or neurological symptoms.

Mitigating Interfacial Mismatch between Lithium Metal and Garnet-Type Solid Electrolyte by Depositing Metal Nitride Lithiophilic Interlayer.

Solid-state lithium batteries are generally considered as the next-generation battery technology that benefits from inherent nonflammable solid electrolytes and safe harnessing of high-capacity lithium metal. Among various solid-electrolyte candidates, cubic garnet-type Li7La3Zr2O12 ceramics hold superiority due to their high ionic conductivity (10-3 to 10-4 S cm-1) and good chemical stability against lithium metal. However, practical deployment of solid-state batteries based on such garnet-type materials has been constrained by poor interfacing between lithium and garnet that displays high impedance and uneven current distribution. Herein, we propose a facile and effective strategy to significantly reduce this interfacial mismatch by modifying the surface of such garnet-type solid electrolyte with a thin layer of silicon nitride (Si3N4). This interfacial layer ensures an intimate contact with lithium due to its lithiophilic nature and formation of an intermediate lithium-metal alloy. The interfacial resistance experiences an exponential drop from 1197 to 84.5 Ω cm2. Lithium symmetrical cells with Si3N4-modified garnet exhibited low overpotential and long-term stable plating/stripping cycles at room temperature compared to bare garnet. Furthermore, a hybrid solid-state battery with Si3N4-modified garnet sandwiched between lithium metal anode and LiFePO4 cathode was demonstrated to operate with high cycling efficiency, excellent rate capability, and good electrochemical stability. This work represents a significant advancement toward use of garnet solid electrolytes in lithium metal batteries for the next-generation energy storage devices.

Incidental finding of Langerhans cell histiocytosis of temporoparietal bone - A case report.

INTRODUCTION AND IMPORTANCE: Langerhans cell histiocytosis (LCH) is a rare haematological disorder affecting infants and young children and has an estimated incidence of 2-5 cases per million people per year. LCH invades the reticuloendothelial system and causes the proliferation of Langerhans cells and mature eosinophils. LCH involving the temporoparietal bone has rarely been reported in the literature. PRESENTATION OF CASE: A ten-year-old boy presented to the Neurosurgical outpatient clinic with a swelling on the right temporoparietal region following a fall from his bicycle. Local examination revealed a single, 3 × 3 cm, non-tender, cystic, immobile swelling in the right temporoparietal region. On evaluation for recent head trauma, an incidental finding of eosinophilic granuloma was discovered on a CT scan. The FNAC was suggestive of a histiocytic lesion pertaining to a diagnosis of LCH. The patient underwent wide excision of the mass and cranioplasty. A one-month follow-up CT scan of the head had no evidence of residual or recurrent disease. DISCUSSION: Eosinophilic granuloma is one of the three variants of LCH and has a relatively better prognosis. Clinical diagnosis can be challenging and mandates tissue sampling for histopathological examination. Treatment modalities including surgery, radiotherapy, chemotherapy, and steroid injection are used alone, or in combination, depending on the extent and severity of the disease. CONCLUSION: Examining a swelling in the temporoparietal region with no other characteristic symptoms could be a case of LCH. The timely diagnosis and surgical excision with other adjuvant treatment options of this rare pediatric disease would help in a better outcome.

Grain Boundary Defect Passivation of Triple Cation Mixed Halide Perovskite with Hydrazine-Based Aromatic Iodide for Efficiency Improvement.

Perovskites have been unprecedented with a relatively sharp rise in power conversion efficiency in the last decade. However, the polycrystalline nature of the perovskite film makes it susceptible to surface and grain boundary defects, which significantly impedes its potential performance. Passivation of these defects has been an effective approach to further improve the photovoltaic performance of the perovskite solar cells. Here, we report the use of a novel hydrazine-based aromatic iodide salt or phenyl hydrazinium iodide (PHI) for secondary post treatment to passivate surface and grain boundary defects in triple cation mixed halide perovskite films. In particular, the PHI post treatment reduced current at the grain boundaries, facilitated an electron barrier, and reduced trap state density, indicating suppression of leakage pathways and charge recombination, thus passivating the grain boundaries. As a result, a significant enhancement in power conversion efficiency to 20.6% was obtained for the PHI-treated perovskite device in comparison to a control device with 17.4%.

Transparent MoS2/PEDOT Composite Counter Electrodes for Bifacial Dye-Sensitized Solar Cells.

Dye-sensitized solar cells (DSSCs) are solar energy conversion devices with high efficiency and simple fabrication procedures. Developing transparent counter electrode (CE) materials for bifacial DSSCs can address the needs of window-type building-integrated photovoltaics (BIPVs). Herein, transparent organic-inorganic hybrid composite films of molybdenum disulfide and poly(3,4-ethylenedioxythiophene) (MoS2/PEDOT) are prepared to take full advantage of the conductivity and electrocatalytic ability of the two components. MoS2 is synthesized by hydrothermal method and spin-coated to form the MoS2 layer, and then PEDOT films are electrochemically polymerized on top of the MoS2 film to form the composite CEs. The DSSC with the optimized MoS2/PEDOT composite CE shows power conversion efficiency (PCE) of 7% under front illumination and 4.82% under back illumination. Compared with the DSSC made by the PEDOT CE and the Pt CE, the DSSC fabricated by the MoS2/PEDOT composite CE improves the PCE by 10.6% and 6.4% for front illumination, respectively. It proves that the transparent MoS2/PEDOT CE owes superior conductivity and catalytic properties, and it is an excellent candidate for bifacial DSSC in the application of BIPVs.

Fluorinated hybrid solid-electrolyte-interphase for dendrite-free lithium deposition.

Lithium metal anodes have attracted extensive attention owing to their high theoretical specific capacity. However, the notorious reactivity of lithium prevents their practical applications, as evidenced by the undesired lithium dendrite growth and unstable solid electrolyte interphase formation. Here, we develop a facile, cost-effective and one-step approach to create an artificial lithium metal/electrolyte interphase by treating the lithium anode with a tin-containing electrolyte. As a result, an artificial solid electrolyte interphase composed of lithium fluoride, tin, and the tin-lithium alloy is formed, which not only ensures fast lithium-ion diffusion and suppresses lithium dendrite growth but also brings a synergistic effect of storing lithium via a reversible tin-lithium alloy formation and enabling lithium plating underneath it. With such an artificial solid electrolyte interphase, lithium symmetrical cells show outstanding plating/stripping cycles, and the full cell exhibits remarkably better cycling stability and capacity retention as well as capacity utilization at high rates compared to bare lithium.

High-performance carbon electrode-based CsPbI2Br inorganic perovskite solar cell based on poly(3-hexylthiophene)-carbon nanotubes composite hole-transporting layer.

CsPbI2Br inorganic perovskite has been considered as a promising candidate for application in photovoltaic devices due to its high thermal stability and reasonable bandgap of 1.92 eV. However, CsPbI2Br perovskite is sensitive to moisture, which remarkably deteriorates the stability of CsPbI2Br perovskite solar cells under the ambient conditions. Here, by using hydrophobic poly(3-hexylthiophene) (P3HT) layer in conjunction with multi-walled carbon nanotubes (MWCNTs) as the hole transporting layer, we develop a stable and high-performance carbon electrode-based CsPbI2Br inorganic perovskite solar cell (PSC). The P3HT-MWCNTs composites not only can prevent moisture ingress but also enhance the holes extraction and transport. A conversion efficiency up to 10.01% with a stabilized efficiency of 8.85% is achieved for the champion device. In addition, the as-prepared carbon electrode-based CsPbI2Br PSC exhibits an excellent long-term stability which retains ∼85% of its initial value over 240 h under the ambient conditions (∼35% R.H.) without encapsulation.

Self-recovery in Li-metal hybrid lithium-ion batteries via WO3 reduction.

It has been a challenge to use transition metal oxides as anode materials in Li-ion batteries due to their low electronic conductivity, poor rate capability and large volume change during charge/discharge processes. Here, we present the first demonstration of a unique self-recovery of capacity in transition metal oxide anodes. This was achieved by reducing tungsten trioxide (WO3) via the incorporation of urea, followed by annealing in a nitrogen environment. The reduced WO3 successfully self-retained the Li-ion cell capacity after undergoing a sharp decrease upon cycling. Significantly, the reduced WO3 also exhibited excellent rate capability. The reduced WO3 exhibited an interesting cycling phenomenon where the capacity was significantly self-recovered after an initial sharp decrease. The quick self-recoveries of 193.21%, 179.19% and 166.38% for the reduced WO3 were observed at the 15th (521.59/457.41 mA h g-1), 36th (538.49/536.61 mA h g-1) and 45th (555.39/555.39 mA h g-1) cycles respectively compared to their respective preceding discharge capacity. This unique self-recovery phenomenon can be attributed to the lithium plating and conversion reaction which might be due to the activation of oxygen vacancies that act as defects which make the WO3 electrode more electrochemically reactive with cycling. The reduced WO3 exhibited a superior electrochemical performance with 959.1/638.9 mA h g-1 (1st cycle) and 558.68/550.23 mA h g-1 (100th cycle) vs. pristine WO3 with 670.16/403.79 mA h g-1 (1st cycle) and 236.53/234.39 mA h g-1 (100th cycle) at a current density of 100 mA g-1.

Binder Free Hierarchical Mesoporous Carbon Foam for High Performance Lithium Ion Battery.

A hierarchical mesoporous carbon foam (ECF) with an interconnected micro-/mesoporous architecture was prepared and used as a binder-free, low-cost, high-performance anode for lithium ion batteries. Due to its high specific surface area (980.6 m2/g), high porosity (99.6%), light weight (5 mg/cm3) and narrow pore size distribution (~2 to 5 nm), the ECF anode exhibited a high reversible specific capacity of 455 mAh/g. Experimental results also demonstrated that the anode thickness significantly influence the specific capacity of the battery. Meanwhile, the ECF anode retained a high rate performance and an excellent cycling performance approaching 100% of its initial capacity over 300 cycles at 0.1 A/g. In addition, no binders, carbon additives or current collectors are added to the ECF based cells that will increase the total weight of devices. The high electrochemical performance was mainly attributed to the combined favorable hierarchical structures which can facilitate the Li+ accessibility and also enable the fast diffusion of electron into the electrode during the charge and discharge process. The synthesis process used to make this elastic carbon foam is readily scalable to industrial applications in energy storage devices such as li-ion battery and supercapacitor.

A simple acrylic acid functionalized zinc porphyrin for cost-effective dye-sensitized solar cells.

A simple zinc porphyrin with an acrylic acid at the meso position exhibits an energy conversion efficiency of 5.1%, demonstrating its potential for cost-effective dye-sensitized solar cells.

8-Hydroxylquinoline as a strong alternative anchoring group for porphyrin-sensitized solar cells.

8-Hydroxylquinoline (OQ) is demonstrated for the first time as a strong alternative anchoring group porphyrin dyes to improve the long-term stability of solar cells.