A Fast-Charge Graphite Anode with a Li-Ion-Conductive, Electron/Solvent-Repelling Interface.

Graphite has been serving as the key anode material of rechargeable Li-ion batteries, yet is difficultly charged within a quarter hour while maintaining stable electrochemistry. In addition to a defective edge structure that prevents fast Li-ion entry, the high-rate performance of graphite could be hampered by co-intercalation and parasitic reduction of solvent molecules at anode/electrolyte interface. Conventional surface modification by pitch-derived carbon barely isolates the solvent and electrons, and usually lead to inadequate rate capability to meet practical fast-charge requirements. Here we show that, by applying a MoOx-MoNx layer onto graphite surface, the interface allows fast Li-ion diffusion yet blocks solvent access and electron leakage. By regulating interfacial mass and charge transfer, the modified graphite anode delivers a reversible capacity of 340.3 mAh g-1 after 4000 cycles at 6 C, showing promises in building 10-min-rechargeable batteries with a long operation life.

[Effect of acupuncture exercise therapy synchronizing isokinetic muscle strength training for postoperative rehabilitation of meniscectomy under arthroscopy].

OBJECTIVE: To observe the effect of acupuncture exercise therapy synchronizing isokinetic muscle strength training on the motor function, stability and proprioception of knee joint, as well as the anxiety emotion in patients after meniscectomy under arthroscopy. METHODS: A total of 70 patients after meniscectomy under arthroscopy were randomized into an observation group (35 cases, 2 cases were eliminated， 2 cases dropped off) and a control group (35 cases, 2 cases were eliminated, 1 case dropped off). Acupuncture was applied at Chize (LU 5), Neixiyan (EX-LE 4), Dubi (ST 35),Yanglingquan (GB 34), etc. on the affective side in the two groups. After 30 min, the needles of the knee joint area were withdrew, while the needle at elbow was continuously retained, the observation group was given acupuncture exercise therapy synchronizing isokinetic muscle strength training, and the control group was given conventional acupuncture exercise therapy. The treatment was given once a day, 7-day treatment was taken as one course, and totally 4 courses were required in the two groups. Before and after treatment, the knee joint Lysholm score, the knee joint isokinetic muscle strength flexion/extension ratio (H/Q), joint position sense measurement (JPS) and Hamilton anxiety scale (HAMA) score were compared in the two groups. RESULTS: After treatment, the knee joint Lysholm scores and H/Q were increased compared with those before treatment in the two groups (P<0.001), and the knee joint Lysholm score and H/Q in the observation group were higher than those in the control group (P<0.001); the JPS and HAMA scores were decreased compared with those before treatment in the two groups (P<0.001), the JPS and HAMA score in the observation group were lower than those in the control group (P<0.05). CONCLUSION: Acupuncture exercise therapy synchronizing isokinetic muscle strength training can effectively improve the motor function, stability and proprioception of knee joint, as well as the anxiety emotion in patients after meniscectomy under arthroscopy.

Mitigating Swelling of the Solid Electrolyte Interphase using an Inorganic Anion Switch for Low-temperature Lithium-ion Batteries.

In overcoming the Li+ desolvation barrier for low-temperature battery operation, a weakly-solvated electrolyte based on carboxylate solvent has shown promises. In case of an organic-anion-enriched primary solvation sheath (PSS), we found that the electrolyte tends to form a highly swollen, unstable solid electrolyte interphase (SEI) that shows a high permeability to the electrolyte components, accounting for quickly declined electrochemical performance of graphite-based anode. Here we proposed a facile strategy to tune the swelling property of SEI by introducing an inorganic anion switch into the PSS, via LiDFP co-solute method. By forming a low-swelling, Li3 PO4 -rich SEI, the electrolyte-consuming parasitic reactions and solvent co-intercalation at graphite-electrolyte interface are suppressed, which contributes to efficient Li+ transport, reversible Li+ (de)intercalation and stable structural evolution of graphite anode in high-energy Li-ion batteries at a low temperature of -20 °C.

Building a Self-Adaptive Protective Layer on Ni-Rich Layered Cathodes to Enhance the Cycle Stability of Lithium-Ion Batteries.

Layered Ni-rich lithium transition metal oxides are promising battery cathodes due to their high specific capacity, but their poor cycling stability due to intergranular cracks in secondary particles restricts their practical applications. Surface engineering is an effective strategy for improving a cathode's cycling stability, but most reported surface coatings cannot adapt to the dynamic volume changes of cathodes. Herein, a self-adaptive polymer (polyrotaxane-co-poly(acrylic acid)) interfacial layer is built on LiNi0.6 Co0.2 Mn0.2 O2 . The polymer layer with a slide-ring structure exhibits high toughness and can withstand the stress caused by particle volume changes, which can prevent the cracking of particles. In addition, the slide-ring polymer acts as a physicochemical barrier that suppresses surface side reactions and alleviates the dissolution of transition metallic ions, which ensures stable cycling performance. Thus, the as-prepared cathode shows significantly improved long-term cycling stability in situations in which cracks may easily occur, especially under high-rate, high-voltage, and high-temperature conditions.

Cooperative Shielding of Bi-Electrodes via In Situ Amorphous Electrode-Electrolyte Interphases for Practical High-Energy Lithium-Metal Batteries.

Solid-state Li-metal batteries offer a great opportunity for high-security and high-energy-density energy storage systems. However, redundant interfacial modification layers, intended to lead to an overall satisfactory interfacial stability, dramatically debase the actual energy density. Herein, a dual-interface amorphous cathode electrolyte interphase/solid electrolyte interphase CEI/SEI protection (DACP) strategy is proposed to conquer the main challenges of electrochemical side reactions and Li dendrites in hybrid solid-liquid batteries without sacrificing energy density via LiDFOB and LiBF4 in situ synergistic conversion. The amorphous CEI/SEI products have an ultralow mass proportion and act as a dynamic shield to cooperatively enforce dual electrodes with a well-preserved structure. Thus, this in situ DACP layer subtly reconciles multiple interfacial compatibilities and a high energy density, endowing the hybrid solid-liquid Li-metal battery with a sustainably brilliant cycling stability even at practical conditions, including high cathode loading, high voltage (4.5 V), and high temperature (45 °C) conditions, and enables a high-energy-density (456 Wh kg-1) pouch cell (11.2 Ah, 5 mA h cm-2) with a lean electrolyte (0.92 g Ah-1, containing solid and liquid phases). The compatible modification strategy points out a promising approach for the design of practical interfaces in future solid-state battery systems.

Revealing the Superiority of Fast Ion Conductor in Composite Electrolyte for Dendrite-Free Lithium-Metal Batteries.

Composite electrolytes composed of a nanoceramic and polymer have been widely studied because of their high ionic conductivity, good Li-ion transference number, and excellent machinability, whereas the intrinsic reason for the improvement of performance is ambiguous. Herein, we have designed a functional polymer skeleton with different types of nanofiller to reveal the superiority of fast ion conductors in composite electrolyte. Three types of ceramics with different dielectric constants and Li-ion transfer ability were selected to prepare composite electrolytes, the composition, structure, and electrochemical performances of which were systematically investigated. It was found that the addition of fast ion conductive ceramics could provide a high Li-ion transference ability and decreased diffusion barrier because the additional pathways existed in the ceramic, which are revealed by experiment and density functional theory calculations. Benefiting from the superiority of fast ion conductor, Li-metal batteries with this advanced composite electrolyte exhibit an impressive cycling stability and enable a dendrite-free Li surface after cycling. Our work enriches the understanding of the function of fast ion conductors in composite electrolyte and guides the design for other high-performance composite electrolytes in rechargeable solid batteries.

Enabling a Durable Electrochemical Interface via an Artificial Amorphous Cathode Electrolyte Interphase for Hybrid Solid/Liquid Lithium-Metal Batteries.

A hybrid solid/liquid electrolyte with superior security facilitates the implementation of high-energy-density storage devices, but it suffers from inferior chemical compatibility with cathodes. Herein, an optimal lithium difluoro(oxalato)borate salt was introduced to build in situ an amorphous cathode electrolyte interphase (CEI) between Ni-rich cathodes and hybrid electrolyte. The CEI preserves the surface structure with high compatibility, leading to enhanced interfacial stability. Meanwhile, the space-charge layer can be prominently mitigated at the solid/solid interface via harmonized chemical potentials, acquiring promoted interfacial dynamics as revealed by COMSOL simulation. Consequently, the amorphous CEI integrates the bifunctionality to provide an excellent cycling stability, high Coulombic efficiency, and favorable rate capability in high-voltage Li-metal batteries, innovating the design philosophy of functional CEI strategy for future high-energy-density batteries.

Self-Healable Solid Polymeric Electrolytes for Stable and Flexible Lithium Metal Batteries.

The key issue holding back the application of solid polymeric electrolytes in high-energy density lithium metal batteries is the contradictory requirements of high ion conductivity and mechanical stability. In this work, self-healable solid polymeric electrolytes (SHSPEs) with rigid-flexible backbones and high ion conductivity are synthesized by a facile condensation polymerization approach. The all-solid Li metal full batteries based on the SHSPEs possess freely bending flexibility and stable cycling performance as a result of the more disciplined metal Li plating/stripping, which have great implications as long-lifespan energy sources compatible with other wearable devices.

Engineering Janus Interfaces of Ceramic Electrolyte via Distinct Functional Polymers for Stable High-Voltage Li-Metal Batteries.

The fast-ionic-conducting ceramic electrolyte is promising for next-generation high-energy-density Li-metal batteries, yet its application suffers from the high interfacial resistance and poor interfacial stability. In this study, the compatible solid-state electrolyte was designed by coating Li1.4Al0.4Ti1.6(PO4)3 (LATP) with polyacrylonitrile (PAN) and polyethylene oxide (PEO) oppositely to satisfy deliberately the disparate interface demands. Wherein, the upper PAN constructs soft-contact with LiNi0.6Mn0.2Co0.2O2, and the lower PEO protects LATP from being reduced, guaranteeing high-voltage tolerance and improved stability toward Li-metal anode performed in one ceramic. Moreover, the core function of LATP is amplified to guide homogeneous ions distribution and hence suppresses the formation of a space-charge layer across interfaces, uncovered by the COMSOL Multiphysics concentration field simulation. Thus, such a bifunctional modified ceramic electrolyte integrates the respective superiority to render Li-metal batteries with excellent cycling stability (89% after 120 cycles), high Coulombic efficiency (exceeding 99.5% per cycle), and a dendrite-free Li anode at 60 °C, which represents an overall design of ceramic interface engineering for future practical solid battery systems.

Suppressing Surface Lattice Oxygen Release of Li-Rich Cathode Materials via Heterostructured Spinel Li4 Mn5 O12 Coating.

Lithium-rich layered oxides with the capability to realize extraordinary capacity through anodic redox as well as classical cationic redox have spurred extensive attention. However, the oxygen-involving process inevitably leads to instability of the oxygen framework and ultimately lattice oxygen release from the surface, which incurs capacity decline, voltage fading, and poor kinetics. Herein, it is identified that this predicament can be diminished by constructing a spinel Li4 Mn5 O12 coating, which is inherently stable in the lattice framework to prevent oxygen release of the lithium-rich layered oxides at the deep delithiated state. The controlled KMnO4 oxidation strategy ensures uniform and integrated encapsulation of Li4 Mn5 O12 with structural compatibility to the layered core. With this layer suppressing oxygen release, the related phase transformation and catalytic side reaction that preferentially start from the surface are consequently hindered, as evidenced by detailed structural evolution during Li+ extraction/insertion. The heterostructure cathode exhibits highly competitive energy-storage properties including capacity retention of 83.1% after 300 cycles at 0.2 C, good voltage stability, and favorable kinetics. These results highlight the essentiality of oxygen framework stability and effectiveness of this spinel Li4 Mn5 O12 coating strategy in stabilizing the surface of lithium-rich layered oxides against lattice oxygen escaping for designing high-performance cathode materials for high-energy-density lithium-ion batteries.

Mitigating Interfacial Potential Drop of Cathode-Solid Electrolyte via Ionic Conductor Layer To Enhance Interface Dynamics for Solid Batteries.

The rapid capacity decay caused by the poor contact and large polarization at the interface between the cathode and solid electrolytes is still a big challenge to overcome for high-power-density solid batteries. In this study, a superior Li+ conductive transition layer Li1.4Al0.4Ti1.6(PO4)3 is introduced to coat LiNi0.6Co0.2Mn0.2O2, as a model cathode, to mitigate polarization and enhance dynamic characteristics. The critical attribute for such superior dynamics is investigated by the atomic force microscopy with boundary potential analysis, revealing that the formed interfacial transition layer provides a gradual potential slope and sustain-released polarization, and endows the battery with improved cycling stability (90% after 100 cycles) and excellent rate capability (116 mA h g-1 at 2 C) at room temperature, which enlightens the comprehension of interface engineering in the future solid batteries systems.