Ultra-fast recovery of cathode materials from spent LiFePO4 lithium-ion batteries by novel electromagnetic separation technology.

The separation of electrode materials from current collectors plays a significant role in determining the leaching efficiency of different metals from spent lithium-ion batteries (LIBs). In the presented research, a highly efficient, environmentally sustainable, and cost-effective cathode materials separation strategy was proposed for spent LiFePO4 batteries. Based on the difference in the thermal expansion coefficient of the binder and aluminum foil, the electromagnetic induction system was examined to harvest cathode materials for the first time, which could provide a high heating rate to erase the mechanical interlocking force between Al foil and coated material, and breaking the chemical bond or Van der Waals forces of the binder. The process avoids the usage of any chemicals such as acids and alkalis, thus eliminating the emission of wastewater. Our system shows ultra-fast separation (3 min) and achieves high-purity of recovered electrode materials and Al foils (99.6% and 99.2%). Furthermore, the morphology and crystalline structure of delaminated electrode materials remain almost the same compared with the pristine materials, which provides a previously unexplored technology to realize sustainable spent battery recycling.

Hybrid Solid Electrolyte Interphases Enabled Ultralong Life Ca-Metal Batteries Working at Room Temperature.

Currently, the application of calcium metal anodes is challenged by rapidly degenerated plating/stripping electrochemistry without suitable solid electrolyte interphases (SEIs) capable of fast Ca2+ transport kinetics and superior ability to resist anion oxidation. Here, through in situ evolved Na/Ca hybrid SEIs, symmetrical Ca//Ca batteries readily remain stable for more than 1000 h deposition-dissolution cycles (versus less than 60 h for those with pure Ca SEIs under the same condition). Coupled with a specially designed freestanding lattice-expanded graphitic carbon fiber membrane and tailored operation voltages, the proof-of-concept Ca-metal batteries reversibly run for almost 1900 cycles with ≈83% capacity retention and a high average discharge voltage of 3.16 V. The good performance not only benefits from the stable SEIs at the Ca metal surface which affords free Ca2+ transports and prohibits out-of-control fluridation of Ca (forming CaF2 ion-/electron-insulating layer) but is also attributed to reversible relay insertion/extraction electrochemistry in the cathode. This work sheds new light on durable metal battery technology.

Facile Universal Mass Production Strategy to Sub-3 nm Monodisperse Nanocrystals of Transition-Metal Oxides and Their Excellent Cyclability for Li-Ion Storage.

Nanoparticles, especially ultrasmall ones in sub-3 nm realms, are fundamental to high activity, high efficiency, and high utilization (3-H) important for many fields. Meanwhile, controlling the crystallinity, surfaces/interfaces, and pores, especially dimension-tunable aspect in them, is also of great significance in synthetic chemistry and nanoengineering. However, controlling crystallization down to a scale of sub-3 nm in mass production, even of subnucleus scale, is rare and still challenging. Here, using Mn, Co, and Zn elements as examples, homogeneous subnuclei smaller than 1 nm and size-tunable sub-3 nm monodisperse nanocrystals have been realized in laminated transition-metal oxides bulk foams (TMOBFs) of gram scale by a two-step fast evaporation-solidification (FE-S) and annealing strategy. Realization of the challenging size controllability in ultrasmall nanocrystals benefits from the FE-S-related burst nucleation process and in situ inhibition of crystal growth, while formation of the nanosheet skeletons is impelled by multiscale bubbling effect. Relying on annealing temperature and durations, the involved TMOBFs also exhibit controllable inorganic crystallization, organic surface/interfaces, and abundant micro/mesopores. In an illustration of the proof-of-concept application, TMOBFs with sub-3 nm nanocrystals substantiate universally ultrasteady cycling performance and approximate 100% utilization efficiency as anodes materials for lithium-ion batteries as expected.

Surfaces/Interfaces Modification for Vacancies Enhancing Lithium Storage Capability of Cu2O Ultrasmall Nanocrystals.

Theoretically, Cu2O delivers a poor Li storage capacity ∼373.9 mA h g-1 based on a so-called conversion reaction (Cu2O + 2Li → 2Cu + Li2O). Herein, we broke through the bottleneck and acquired an impressive lithium storage capability (1122 mA h g-1) tripled more than the theoretical one by an in situ surface/interface engineering process for the first time. The surface/interface modification enabled us to fabricate ultrasmall nanocrystals of Cu2O with Cu vacancies (VCu) of high concentration, somewhat like monovalent anion doping. Except for the conversion reaction-type capacity, VCu enhancing intercalation pesudocapacitance in Cu2O and its reduction product-Cu also contributed a lot to the Li-storage capability. First-principles calculation substantiated that intercalation energy of Li was severely lowered for both Cu vacancy-rich Cu2O and Cu comparing with their stoichiometric counterparts. Another important factor for the enhancement was the surface/interface organic species themselves which could reversibly store Li by redox reactions. The surface/interface modification for vacancies, vacancy inheritance from metal oxide to single metal, and vacancy-enhancing Li-storage capability in metal oxide and single metal all will inspire us a lot in fabricating new-generation advanced electrodes for rechargeable batteries.

CuFeS2 Quantum Dots Anchored in Carbon Frame: Superior Lithium Storage Performance and the Study of Electrochemical Mechanism.

Herein, we report a simple and quick synthetic route to prepare the pure CuFeS2 quantum dots (QDs) @C composites with the unique structure of CuFeS2 QDs encapsulated in the carbon frame. When tested as anode materials for the lithium ion battery, the CuFeS2 QDs @C composites based electrodes exhibit excellent electrochemical performances. When charge-discharge occurred with a current density of 0.5 A g-1, the electrodes exhibit a high reversible capacity (760 mA h g-1) for as long as 700 cycles, which indicates the superior cycling life. Detailed investigations of the morphological and structural changes of CuFeS2 QDs by ex situ XRD, ex situ Raman, and ex situ TEM reveal an interesting electrochemical reaction mechanism, a hybrid of a lithium-copper iron sulfide battery and lithium-sulfur battery. The direct observation of orthorhombic FeS2 by HRTEM and the existence of Li2FeS2 detected by Raman support our assertion. We believe such an electrochemical mechanism would attract more attention to the CuFeS2 nanomaterials as lithium ion battery anode materials. The excellent electrochemical properties would be derived from the unique structure, which include CuFeS2 QDs encapsulated in the carbon frame.

[Surgical outcome of percutaneous endoscopic technique for highly migrated disc herniation via three different approaches].

OBJECTIVE: To analyze the clinical effects of percutaneous endoscopic technique via three different approaches for highly migrated lumbar disc herniation. METHODS: The clinical data of 68 patients underwent percutaneous endoscopic technique from June 2011 to June 2014 were retrospectively analyzed. There were 43 males and 25 females, aged from 11 to 77 years old with an average of (42.29±15.92) years. The patients were divided into three groups according to different operative approaches, of them, 45 cases were by transforaminal approach (group A), 15 cases by translaminar approach (group B), and 8 cases by transpedicular approach (group C). There was 1 case in level L2,3, 12 cases in L3,4, 36 cases in L4,5, 19 cases in L5S1. The herniated disc was migrated superiorly in 23 patients, inferiorly in 45 patients. MRI were available to confirm migrated disc pre-and post-operatively. Operation time, loss blood volume, intraoperative and postoperative complications, time of back to work (postoperative recovery time) were recorded. Preoperative and postoperative VAS were used to evaluate low back pain and sciatica and JOA and MacNab criteria were used to evaluate functional recovery. RESULTS: All the operations were successful and all the patients were followed up from 12 to 40 months with an average of (18.0±15.9) months. Seven patients(3 cases in group A, 3 cases in group B, 1 case in group C) complicated with transient paraesthesia (hyperalgesia or hypesthesia), and the symptoms relieved after symptomatic treatment with neurotrophic medicine, at final follow-up, no symptoms were left. One case in group B complicated with dura mater tearing during operation and it was untreated, there was no resulted complications such as headache and sinus tract of skin. In group A, B, C, the mean VAS score of sciatica improved from preoperative 6.93±1.34, 6.33±1.23, 6.13±1.73 to 0.80±0.87, 0.73±0.70, 0.38±0.52 at final follow-up; and JOA score improved from preoperative 9.09±2.62, 9.80±2.31, 10.50±2.93 to 26.82±1.53, 25.93±1.58, 26.50±1.51 at final follow-up, respectively(P<0.05). There was no significant difference among three groups(P>0.05). There was no significant difference in loss blood volume, postoperative recovery time among three groups. But operation time of group B was shorter than other two groups. According to MacNab criterion to assess the clinical effects, 42 cases got excellent results, 21 good, 5 fair. CONCLUSIONS: Percutaneous endoscopic technique is a safe and effective method for surgical treatment of highly migrated herniation. The decision of operative approach should be made by characters of anatomy. By tanspedicular approach the lesion could be found directly. However, it depends on good skill and equipment.

Amorphous ZnO Quantum Dot/Mesoporous Carbon Bubble Composites for a High-Performance Lithium-Ion Battery Anode.

Due to its high theoretical capacity (978 mA h g-1), natural abundance, environmental friendliness, and low cost, zinc oxide is regarded as one of the most promising anode materials for lithium-ion batteries (LIBs). A lot of research has been done in the past few years on this topic. However, hardly any research on amorphous ZnO for LIB anodes has been reported despite the fact that the amorphous type could have superior electrochemical performance due to its isotropic nature, abundant active sites, better buffer effect, and different electrochemical reaction details. In this work, we develop a simple route to prepare an amorphous ZnO quantum dot (QDs)/mesoporous carbon bubble composite. The composite consists of two parts: mesoporous carbon bubbles as a flexible skeleton and monodisperse amorphous zinc oxide QDs (smaller than 3 nm) encapsulated in an amorphous carbon matrix as a continuous coating tightly anchored on the surface of mesoporous carbon bubbles. With the benefits of abundant active sites, amorphous nature, high specific surface area, buffer effect, hierarchical pores, stable interconnected conductive network, and multidimensional electron transport pathways, the amorphous ZnO QD/mesoporous carbon bubble composite delivers a high reversible capacity of nearly 930 mA h g-1 (at current density of 100 mA g-1) with almost 90% retention for 85 cycles and possesses a good rate performance. This work opens the possibility to fabricate high-performance electrode materials for LIBs, especially for amorphous metal oxide-based materials.

Ultrathin Hexagonal 2D Co2GeO4 Nanosheets: Excellent Li-Storage Performance and ex Situ Investigation of Electrochemical Mechanism.

Two-dimensional (2D) nanostructures are a desirable configuration for lithium ion battery (LIB) electrodes due to their large open surface and short pathway for lithium ions. Therefore, exploring new anode materials with 2D structure could be a promising direction to develop high-performance LIBs. Herein, we synthesized a new type of 2D Ge-based double metal oxides for lithium storage. Ultrathin hexagonal Co2GeO4 nanosheets with nanochannels are prepared by a simple hydrothermal method. When used as LIB anode, the sample delivers excellent cyclability and rate capability. A highly stable capacity of 1026 mAhg(-1) was recorded after 150 cycles. Detailed morphology and phase evolutions were detected by TEM and EELS measurements. It is found that Co2GeO4 decomposed into Ge NPs which are evenly dispersed in amorphous Co/Li2O matrix during the cycling process. Interestingly, the in situ formed Co matrix could serve as a conductive network for electrochemical process of Ge. Moreover, aggregations of Ge NPs could be restricted by the ultrathin configuration and Co/Li2O skeleton, leading to unique structure stability. Hence, the large surface areas, ultrathin thickness, and atomically metal matrix finally bring the superior electrochemical performance.

Hollow Ball-in-Ball CoxFe3-xO4 Nanostructures: High-Performance Anode Materials for Lithium-Ion Battery.

The intrinsic electronic conductivity can be improved by doping efficiently. CoxFe3-xO4 nanostructures have been synthesized for the first time to improve the conductivity of lithium battery electrode. The solid solution CoxFe3--xO4 were characterized by X-ray diffraction pattern (XRD), Raman spectrum, scanning electron microscopy (SEM), transmission electron microscope (TEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results show that the doping enlarge the lattice spacing but the structure of Co3O4 is stable in the Li-ion intercalation/deintercalation process. The AC impedance spectrum reveals the conductivity is well improved. In addition, the solid solution CoxFe3-xO4 exhibit excellent electrochemical characteristics. The electrodes with 20% molar ratio of Fe ions own a reversible capacity of 650.2 mA h g(-1) at a current density of 1 A g(-1) after 100 cycles.

Free-Standing and Transparent Graphene Membrane of Polyhedron Box-Shaped Basic Building Units Directly Grown Using a NaCl Template for Flexible Transparent and Stretchable Solid-State Supercapacitors.

Transparency has never been integrated into freestanding flexible graphene paper (FF-GP), although FF-GP has been discussed extensively, because a thin transparent graphene sheet will fracture easily when the template or substrate is removed using traditional methods. Here, transparent FF-GP (FFT-GP) was developed using NaCl as the template and was applied in transparent and stretchable supercapacitors. The capacitance was improved by nearly 1000-fold compared with that of the laminated or wrinkled chemical vapor deposition graphene-film-based supercapacitors.

General scalable strategy toward heterogeneously doped hierarchical porous graphitic carbon bubbles for lithium-ion battery anodes.

Novel carbon nanostructures, e.g., carbon nanotubes (CNTs), graphene, hierarchical porous graphitic carbon (HPGC), and ordered mesoporous carbon (CMK-3), have been significantly forwarding the progress of energy storage and conversion. Advanced electrodes or hybrid electrodes based on them are springing up one after another. To step further, a generic synthetic approach to large scale hierarchical porous graphitic carbon microbubbles (HPGCMBs) is developed by zinc powder templated organic precursor impregnation method. The facile technique features scalable (yield: once more than 200 mg), in situ heteroatom's doping (doping ratio: more than 26%) and hierarchical-pore-creating traits (pore volume: 1.01 cm(3) g(-1)). Adjustable graphitic content, doping species and amount are readily realized through varying the organic precursors. Rationally, good conductivity, fast kinetics, and abundant ion reservoirs are entirely achieved. To be applied in practice, state-of-the-art anodes for lithium-ion batteries are fabricated. Benefiting from the large specific surface area, rich heteroatoms, and hierarchical pores, the HPGCMBs electrodes exhibit excellent electrochemical properties. Besides superior storage capability of more than 1000 mAh g(-1) at 100 mA g(-1), stable cycling and excellent retention of 370 mAh g(-1) at large rate of 10 A g(-1) are achieved in the meantime.

Abnormal cyclibility in Ni@graphene core-shell and yolk-shell nanostructures for lithium ion battery anodes.

Electrochemical pulverization, a commonly undesirable process for durable electrodes, is reinterpreted in popular yolk-shell nanostructures. In comparison with core-shell counterparts, the yolk-shell ones exhibit enhancing ion storage and rate capability for lithium ion battery anodes. The enhancement benefits from lowered activation barriers for lithiation and delithiation, improved surfaces and interfaces for ion availability contributed by endless pulverization of active materials. By controlled etching, stable cycling with significantly improved capacity (∼800 mAh g(-1) at 0.1 A g(-1), 600 mAh g(-1) at 0.5 A g(-1), and 490 mAh g(-1) at 1 A g(-1) vs 140 mAh g(-1) at 0.1 A g(-1)) is achieved at various rates for Ni@Graphene yolk-shell structures. Meanwhile, large rate of 20 A g(-1) with capacity of 145 mAh g(-1) is retained. Given initial pulverization for the activation, the tailored electrodes could stably last for more than 1700 cycles with an impressive capacity of ca. 490 mAh g(-1) at 5 A g(-1). Insights into electrochemical processes by TEM and STEM reveal dispersive pulverized active nanocrystals and the intact protective graphene shells play the leading role.

[Treatment of lumbar intervertebral disc herniation and sciatica with percutaneous transforaminal endoscopic technique].

OBJECTIVE: To analyze the clinical effects of percutaneous transforaminal endoscopic technique in treating lumbar intervertebral disc herniation and sciatica. METHODS: From June 2011 to January 2012,the clinical data of 46 patients with lumbar intervertebral disc herniation and sciatica underwent percutaneous transforaminal endoscopic technique were retrospectively analyzed. There were 28 males and 18 females,ranging in age from 11 to 77 years old with an average of (39.7_ 15.3) years old,20 cases were L5S1 and 26 cases were L4,5. All patients had the symptoms such as lumbago and sciatica and their straight-leg raising test were positive. Straight-leg raising test of patients were instantly repeated after operation;operative time,volume of blood loss,complication, length of stay and duration of back to work or daily life were recorded. The clinical effects were assessed according to the VAS,JOA and JOABPEQ score. RESULTS: All operations were successful,postoperative straight-leg raising test were all negative. Operative time,volume of blood loss,length of stay,duration of back to work or daily life,follow-up time were (93.0+/-28.0) min, (20.0+/-9.0)ml, (3.1+/-1.5) d, (11.6+/-4.2) d, (13.9+/-1.6) months,respectively. VAS score of lumbar before operation and at the 1st and 3rd,6th,12th month after operation were 5.3+/-1.2,1.9+/-1.1,1.0+/-0.8,0.9+/-0.8,0.8+/-0.6,respectively;VAS score of leg before operation and at the 1st and 3rd,6th,12th month after operation were 7.2+ 1.2,0.8+/-1.2,0.5+/-0.8,0.5+/-0.8,0.3+/-0.8,respectively. Five factors of JOABPEQ score,including lumbar pain,lumbar function, locomotor activity,social life viability and mental status,were respectively 27.0+/-30.6,37.3+/-27.4,38.5+/-26.6,33.0+/-13.7,55.4+/-19.0 before operation and 83.6+/-24.8,89.4+/-15.7,87.0+/-17.9,58.4+/-14.6,79.5+/-13.4 at final follow-up. Preoperative and postoperative JOA score were 9.1+/-2.6 and 27.3+/- 1.7, respectively. The postoperative VAS,JOA and JOABPEQ score had significantly improved (P<0.05). CONCLUSION: Percutaneous transforaminal endoscopic technique is safe and effective method in treating lumbar disc herniation and sciatica,it can fleetly relieve pain and the patient can recover daily life and work after treatment.