Phase-engineering modulation of Mn-based oxide cathode for constructing super-stable sodium storage

The Mn-based oxide cathode with enriched crystal phase structure and component diversity can provide the excellent chemistry structure for Na-ion batteries.Nevertheless,the broad application prospect is obstructed by the sluggish Na^(+)kinetics and the phase transitions upon cycling.Herein,we establish the thermodynamically stable phase diagram of various Mn-based oxide composites precisely controlled by sodium content tailoring strategy coupling with co-doping and solid-state reaction.The chemical environment of the P2/P'3 and P2/P3 biphasic composites indicate that the charge compensation mechanism stems from the cooperative contribution of anions and cations.Benefiting from the no phase transition to scavenge the structure strain,P2/P'3 electrode can deliver long cycling stability(capacity retention of 73.8%after 1000 cycles at 10 C)and outstanding rate properties(the discharge capacity of 84.08 mA h g^(-1)at 20 C)than P2/P3 electrode.Furthermore,the DFT calculation demonstrates that the introducing novel P'3 phase can significantly regulate the Na^(+)reaction dynamics and modify the local electron configuration of Mn.The effective phase engineering can provide a reference for designing other high-performance electrode materials for Na-ion batteries.

Interfacial engineering of the layered oxide cathode materials for sodium-ion battery

The layered metal oxides are reviewed as the hopeful cathode materials for high-performance sodium-ion batteries(SIBs)due to their large theoretical capacity,favorable two-dimensional(2D)ion diffusion channel,and simple manipuility.However,their cycling stability,rate capability,and thermal stability are still significantly concerned and highlighted before further practical application.The chemical,mechanical and electrochemical stability of the cathode–electrolyte interfaces upon cycling is of great significance.Herein,the unique structural and electrochemical properties of the layered oxide cathode materials for SIB are reviewed.The mechanism of bulk/surface degradation induced by oxygen evolution,phase transition,microcrack,and electrolyte decomposition is thoroughly understood.Furthermore,the interfacial engineering to construct stable interface through various effective methods is fully discussed.The future outlook and challenges for interfacial engineering in this filed are also summarized.This review should shed light on the rational design and construct of robust interface for applications of superior layered oxide cathodes in SIB and may suggest future research directions.

多级花状尖晶石锰基氧化物纳米片用于高性能锂离子电池（英文）

应.这种独特的结构不仅可以暴露更多的活性位点、缩短离子/电子扩散路径,还可以确保良好的结构稳定性,抑制重复循环过程中的结构应变.本文通过模板导向策略合成多级花状纯相尖晶石锰基氧化物纳米片.通过醇辅助水热法,利用"气泡反应"原理获得的碳酸盐分解来制备取向模板.最终产物尖晶石锰基氧化物纳米片同时满足优异的倍率性能和循环稳定性要求.合成的分层花状高压LiNi(0.5)Mn(1.5)O4(LNMO-HF)元素分布均匀,且无杂相. LNMOHF可以提供142.6 mA h g^-1的高放电容量,在55℃、1C下,其比能量密度为660.7 W h kg^-1.此外,利用这种模板导向策略合成的LiMn2O4(LMO),在1000次循环后,其容量保持率可达88.12%.

Recent advances in visible-light photoredox-catalyzed nitrogen radical cyclization

Visible-light photoredox catalysis is a powerful and attractive strategy for organic molecule activation and new reaction design owing to its environmental-friendly characteristics and unique catalytic mechanisms,and has found wide applications in organic synthesis.This catalytic strategy enables controllable generation of diverse nitrogen-centered radicals(NCRs)under mild conditions,providing access to construction of diverse nitrogencontaining compounds.In this review,we critically illustrate the recent advances in the field of visible-light photoredox-catalyzed cyclization of nitrogen-centered radicals,based on the different radical precursors and activation modes.Wherever possible,particular emphasis is also put on working models and synthetic applications.