Constructing a 700 Wh kg^(-1)-level rechargeable lithium-sulfur pouch cell

Lithium–sulfur(Li–S)batteries are considered as highly promising energy storage devices because of their ultrahigh theoretical energy density of 2600 Wh kg^(-1).The highest practical energy density of Li–S batteries reported at pouch cell level has exceeded 500 Wh kg^(-1),which significantly surpasses that of lithium-ion batteries.Herein,a 700 Wh kg^(-1)-level Li–S pouch cell is successfully constructed.The pouch cell is designed at 6 Ah level with high-sulfur-loading cathodes of 7.4 mgScm^(-2),limited anode excess(50μm in thickness),and lean electrolyte(electrolyte to sulfur ratio of 1.7 gelectrolyteg^(-1)S).Accordingly,an ultrahigh specific capacity of 1563 m A h g^(-1)is achieved with the addition of a redox comediator to afford a practical energy density of 695 Wh kg^(-1)based on the total mass of all components.The pouch cell can operate stably for three cycles and then failed due to rapidly increased polarization at the second discharge plateau.According to failure analysis,electrolyte exhaustion is suggested as the key limiting factor.This work achieves a significant breakthrough in constructing high-energy-density Li–S batteries and propels the development of Li–S batteries toward practical working conditions.

Premature deposition of lithium polysulfide in lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have attracted extensive attention due to ultrahigh theoretical energy density of 2600 Wh kg^(-1).Liquid-solid deposition from dissolved lithium polysulfides(LiPSs)to solid lithium sulfide(Li_(2)S)largely determines the actual battery performances.Herein,a premature liquidsolid deposition process of LiPSs is revealed at higher thermodynamic potential than Li_(2)S deposition in Li-S batteries.The premature solid deposit exhibits higher chemical state and hemispherical morphology in comparison with Li_(2)S,and the premature deposition process is slower in kinetics and higher in deposition dimension.Accordingly,a supersaturation deposition mechanism is proposed to rationalize the above findings based on thermodynamic simulation.This work demonstrates a unique premature liquid-solid deposition process of Li-S batteries.

Etiology for Degenerative Disc Disease

Degenerative disc disease is a multifaceted progressive irreversible condition and an inevitable part of aging,which has been found to be a contributing factor for low back pain and might cause radiculopathy,myelopathy,spinal stenosis,degenerative spondylolisthesis,and herniations.Its etiology is complex and multifactorial.Although genetics influence more dominant,the occupational and mechanical influences still persist as a major risk factor.This review emphasizes up-to-date knowledge regarding etiology of disc degeneration with special consideration on occupational,lifestyle factors,and genetic polymorphisms.

Higher-order polysulfides induced thermal runaway for 1.0 Ah lithium sulfur pouch cells

Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the origins for the thermal runaway of 1.0 Ah cycled Li-S pouch cells.16-cycle pouch cell indicates high safety,heating from 30 to 300 ℃ without thermal runaway,while 16-cycle pouch cell with additional electrolyte undergoes severe thermal runaway at 147.9 ℃,demonstrating the key roles of the electrolyte on the thermal safety of batteries.On the contrary,thermal runaway does not occur for 45-cycle pouch cell despite the addition of the electrolyte.It is found that the higher-order polysulfides(Li_(2)S_(x) ≥ 6)are discovered in 16-cycle electrolyte while the sulfur species in 45-cycle electrolyte are Li_(2)S_(x) ≤ 4.In addition,strong exothermic reactions are discovered between cycled Li and dissolved higher-order polysulfide(Li_(2)S_(6) and Li_(2)S_(8))at 153.0 ℃,driving the thermal runaway of cycled Li-S pouch cells.This work uncovers the potential safety risks of Li-S batteries and negative roles of the polysulfide shuttle for Li-S batteries from the safety view.

Boosting sulfur redox kinetics by a pentacenetetrone redox mediator for high-energy-density lithium-sulfur batteries

Lithium-sulfur(Li-S)battery is considered as a promising energy storage system due to its ultrahigh theoretical energy density of 2,600 Wh·kg^(−1).Redox mediation strategies have been proposed to promote the sluggish sulfur redox kinetics.Nevertheless,the applicability of redox mediators in practical high-energy-density Li-S batteries has seldomly been manifested.In this work,5,7,12,14-pentacenetetrone(PT)is proposed as an effective redox mediator to promote the sulfur redox kinetics under practical working conditions.A high initial specific discharge capacity of 993 mAh·g^(−1) is achieved at 0.1 C with high-sulfur-loading cathodes of 4.0 mgS·cm^(−2)and low electrolyte/sulfur(E/S)ratio of 5μL·mg_(S)^(−1).More importantly,practical Li-S pouch cells with the PT mediator realize an actual initial energy density of 344 Wh·kg^(−1)and cycle stably for 20 cycles wih a high capacity retention of 88%.This work proposes an effective redox mediator and further verifies the redox mediation strategy for practical high-energydensity Li-S batteries.

Atresia of Coronary Sinus Ostium with a Persistent Left Superior Vena Cava Demonstrated on Cardiac Computed Tomography Angiography

To the Editor： A 43-year-old man diagnosed with dilated cardiomyopathy 6 years prior visited our institution recently because of worsened chest congestion with shortness of breath and abdominal distension. The patient had a history of diabetes. His electrocardiography （ECG） demonstrated a sinus rhythm with an mtraventricular conduction disturbance, an atypical left bundle branch block, and a QRS interval of 160 ms. Echocardiographic findings were consistent with dilated cardiomyopathy [bicentric type, Figure la], in which the left atrial diameter was 44 ram, the left ventricular end-diastolic diameter was 78 mm, and the left ventricular ejection fiaction was 30%. The final diagnosis was New York Heart Association Grade Ⅲ dilated cardiomyopathy. To achieve a good prognosis, improve exercise tolerance, and prevent sudden death, cardiac resynchronization therapy （CRT） with defibrillator implantation was advised. However, coronary sinus （CS） abnormalities were observed during the implantation operation. Therefore, it was forced to stop the operation and a cardiac computed tomography angiography （CTA） evaluation of the abnormalities was arranged.

Interrupted aortic arch with multiple vascular malformations

To the Editor:A 66-year-old male patient was referred to the First Hospital of Lanzhou University with complaints of sudden dizziness,with nausea and emesis.His medical history revealed heavy smoking for 40 years,and no other relevant information was found.

A novel endoscopic retrograde cholangiopancreatography technique to reduce stone size in type IV Mirizzi syndrome: avoiding cholangiojejunostomy

To the Editor:Mirizzi syndrome(MS)is a rare type of cholelithiasis with an incidence of 0.1%in all gallstone.[1]cases.Its clinical manifestations and imaging features can sometimes be diffcult to distinguish from those of choledocholithiasis and biliary tumors.s.The traditional treatment for MS is usually surgery,including cholecys-tectomy,exploration of common bile.duct plus T-tube drainage,and cholangiojejunostomy.[2] There have even been reports of endoscopic therapies for MS in recent years,but it is technically difficult and non-feasible in cases where the stones get stuck in the Hartmann pouch.[3]Here we report a case where the MS was downstaged via endoscopic modalities to avoid cholangiojejunostomy.

maging Features of Uterine Leiomyomatosis with the Inferior Vena Cava and the Right Atrium Involvement

To the Editor： A 48-year-old Chinese woman complained of chest tightness, shortness of breath, and palpitations for 8 months. These symptoms were gradually increasing and the edema on both lower limbs appeared 1 month ago. She had a history of uterine fibroids.