Covalent organic frameworks as electrode materials for rechargeable metal-ion batteries

Covalent organic frameworks(COFs),as a class of crystalline porous polymers,featuring designable structures,tunable frameworks,well-defined channels,and tailorable functionalities,have emerged as promising organic electrode materials for rechargeable metal-ion batteries in recent years.Tremendous efforts have been devoted to improving the electrochemical performance of COFs.However,although significant achievements have been made,the electrochemical behaviors of developed COFs are far away from the desirable performance for practical batteries owing to intrinsic problems,such as poor electronic conductivity,the trade-off relationship between capacity and redox potential,and unfavorable micromorphology.In this review,the recent progress in the development of COFs for rechargeable metal-ion batteries is presented,including Li,Na,K,and Zn ion batteries.Various research strategies for improving the electrochemical performance of COFs are summarized in terms of the molecular-level design and the material-level modification.Finally,the major challenges and perspectives of COFs are also discussed in the aspect of large-scale production and electrochemical performance improvements.

A double-layer covered architecture with spinel phase induced by LiPP for Co-free Li-rich cathode with high-rate performance and long lifespan

Co-free Li-rich Mn-based layered oxides are promising candidates for next-generation lithium-ion batteries(LIBs)due to their high specific capacity,high voltage,low cost.However,their commercialization is hindered by limited cycle life and poor rate performance.Herein,an in-situ simple and low-cost strategy with a nanoscale double-layer architecture of lithium polyphosphate(LiPP)and spinel phase covered on top of the bulk layered phase,is developed for Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2)(LMNO)using Li^(+)-conductor LiPP(denoted as LMNO@S-LiPP).With such a double-layer covered architecture,the half-cell of LMNO@S-LiPP delivers an extremely high capacity of 202.5 mAh·g^(−1)at 1 A·g^(−1)and retains 85.3%of the initial capacity after 300 cycles,so far,the best highrate electrochemical performance of all the previously reported LMNOs.The energy density of the full-cell assembled with commercial graphite reaches 620.9 Wh·kg^(−1)(based on total weight of active materials in cathode and anode).Mechanism studies indicate that the superior electrochemical performance of LMNO@S-LiPP is originated from such a nanoscale double-layer covered architecture,which accelerates Li-ion diffusion,restrains oxygen release,inhibits interfacial side reactions,suppresses structural degradation during cycling.Moreover,this strategy is applicable for other high-energy-density cathodes,such as LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2),Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2),LiCoO_(2).Hence,this work presents a simple,cost-effective,scalable strategy for the development of high-performance cathode materials.

A novel oncolytic virus engineered with PD-L1 scFv effectively inhibits tumor growth in a mouse model

The adoptive transfer of engineered chimeric antigen receptor(CAR)T cells has yielded impressive clinical results for targeting hematological cancers.1 However,the advancement of CAR T-cell therapy in solid tumors remains limited,due to the scarcity of tumor antigens that are deemed safe for targeting.Moreover,the requirement of patient-specific autologous T cells for the current standard treatment has also hampered its application.Oncolytic virus(OV)therapy has been classified as another form of novel immunotherapy.

A Li-rich layered-spinel cathode material for high capacity and high rate lithium-ion batteries fabricated via a gas-solid reaction

Lithium-rich layered oxide(LLO)cathode materials have drawn extensive attention due to their ultrahigh specific capacity and energy density.However,their commercialization is still restricted by their low initial coulombic efficiency,slow intrinsic kinetics and structural instability.Herein,a facile surface treatment strategy via gaseous phosphine was designed to improve the rate performance and capacity stability of LLOs.During the solid-gas reaction,phosphine reacted with active oxygen at the surface of LLOs due to its reductivity,forming oxygen vacancies and spinel phase at the surface region.As a result,Li ion conductivity and structural stability were greatly enhanced.The phosphinetreated LLOs(LLO@P)showed a layered-spinel hybrid structure and delivered an outstanding rate performance of156.7 mA h g^-1 at 10 C and a high capacity retention of 74%after 300 cycles at 5 C.

A 2D covalent organic framework with ultra-large interlayer distance as high-rate anode material for lithium-ion batteries

Covalent organic frameworks(COFs)have been broadly investigated for energy storage systems.However,many COF-based anode materials suffer from low utilization of redox-active sites and sluggish ions/electrons transport caused by their densely stacked layers.Thus,it is still a great challenge to obtain COF-based anode materials with fast ions/electrons transport and thus superior rate performance.Herein,a redox-active piperazine-terephthalaldehyde(PA-TA)COF with ultra-large interlayer distance is designed and synthesized for high-rate anode material,which contains piperazine units adopting a chair-shaped conformation with the nonplanar linkages of a tetrahedral configuration.This unique structure renders PA-TA COF an ultra-large interlayer distance of 6.2Å,and further enables it to achieve outstanding rate and cycling performance.With a high specific capacity of 543 mAh·g^(−1) even after 400 cycles at 1.0 A·g^(−1),it still could afford a specific capacity of 207 mAh·g^(−1) even at a high current density of 5.0 A·g^(−1).Our study indicates that expanding the interlayer distance of COFs by rational molecular design would be of great importance to develop high-rate electrode materials for lithium-ion batteries.