Constructing long-cycling crystalline C_(3)N_(4)-based carbonaceous anodes for sodium-ion battery via N configuration control

Carbon nitrides with two-dimensional layered structures and high theoretical capacities are attractive as anode materials for sodium-ion batteries while their low crystallinity and insufficient structural stability strongly restrict their practical applications.Coupling carbon nitrides with conductive carbon may relieve these issues.However,little is known about the influence of nitrogen(N)configurations on the interactions between carbon and C_(3)N_(4),which is fundamentally critical for guiding the precise design of advanced C_(3)N_(4)-related electrodes.Herein,highly crystalline C_(3)N_(4)(poly(triazine imide),PTI)based all-carbon composites were developed by molten salt strategy.More importantly,the vital role of pyrrolic-N for enhancing charge transfer and boosting Na+storage of C_(3)N_(4)-based composites,which was confirmed by both theoretical and experimental evidence,was spot-highlighted for the first time.By elaborately controlling the salt composition,the composite with high pyrrolic-N and minimized graphitic-N content was obtained.Profiting from the formation of highly crystalline PTI and electrochemically favorable pyrrolic-N configurations,the composite delivered an unusual reverse growth and record-level cycling stability even after 5000 cycles along with high reversible capacity and outstanding full-cell capacity retention.This work broadens the energy storage applications of C_(3)N_(4) and provides new prospects for the design of advanced all-carbon electrodes.

An Amorphous Anode for Proton Battery

Developing advanced electrode materials is crucial for improving the electrochemical performances of proton batteries.Currently,the anodes are primarily crystalline materials which suffer from inferior cyclic stability and high electrode potential.Herein,we propose amorphous electrode materials for proton batteries by using a general ion-exchange protocol to introduce multivalent metal cations for activating the host material.Taking Al^(3+)as an example,theoretical and experimental analysis demonstrates electrostatic interaction between metal cations and lattice oxygen,which is the primary barrier for direct introduction of the multivalent cations,is effectively weakened through ion exchange between Al^(3+)and pre-intercalated K+.The as-prepared Al-MoOx anode therefore delivered a remarkable capacity and outstanding cycling stability that outperforms most of the state-of-the-art counterparts.The assembled full cell also achieved a high voltage of 1.37 V.This work opens up new opportunities for developing high-performance electrodes of proton batteries by introducing amorphous materials.

Crystallinity engineering of carbon nitride protective coating for ultra-stable Zn metal anodes

Ineffective control of dendrite growth and side reactions on Zn anodes significantly retards commercialization of aqueous Zn-ion batteries.Unlike conventional interfacial modification strategies that are primarily focused on component optimization or microstructural tuning,herein,we propose a crystallinity engineering strategy by developing highly crystalline carbon nitride protective layers for Zn anodes through molten salt treatment.Interestingly,the highly ordered structure along with sufficient functional polar groups and pre-intercalated Kþendows the coating with high ionic conductivity,strong hydrophilicity,and accelerated ion diffusion kinetics.Theoretical calculations also confirm its enhanced Zn adsorption capability compared to commonly reported carbon nitride with amorphous or semi-crystalline structure and bare Zn.Benefiting from the aforementioned features,the as-synthesized protective layer enables a calendar lifespan of symmetric cells for 1100 h and outstanding stability of full cells with capacity retention of 91.5%after 1500 cycles.This work proposes a new conceptual strategy for Zn anode protection.

基于PO_(4)^(3-)诱导结构调节的SnS基超长循环寿命钠离子电池负极研究

作为过渡金属硫化物的代表, SnS因其优异的理论容量和独特的层状结构被认为是理想的钠离子电池负极材料.然而较差的导电性以及巨大的体积膨胀严重阻碍了SnS作为钠离子电池负极材料的实际应用,如何实现长循环寿命及高可逆容量是发展其作为高性能负极材料的巨大挑战.基于此,本文提出利用具有螯合作用的植酸作为磷源,并将PO_(4)^(3-)-引入SnS层间的结构修饰思路.研究发现不同于常规掺杂手段,以Sn±O±P共价键形式存在的PO_(4)^(3-)作为多向导电柱能够有效抑制SnS的结构塌陷并扩大层间间距,从而实现高效Na~+存储.密度泛函理论计算结果表明PO_(4)^(3-)的引入导致SnS内部电荷分布发生变化并产生内建电场,有效促进了Na^(+)的吸附.因此,所制备的PO_(4)-SnS/NG复合负极材料呈现出优异的超长循环寿命;在5 A g^(-1)下10,000次循环后,材料仍表现出优异的稳定性,每次容量衰减仅为0.0028%.该工作为制备高性能金属硫化物电极材料提供了新思路.

Nitrogen-oxygen co-doped corrugation-like porous carbon for high performance supercapacitor

Nitrogen-oxygen co-doped corrugation-like porous carbon （NO-PC） has been developed by direct pyrolysis of formaldehyde-melamine polymer containing manganese nitrate. The melamine, formaldehyde and manganese nitrate act as nitrogen, oxygen source and pore-foaming agent, respectively. NO-PC exhibits favorable porous architecture for efficient ion transfer and moderate heteroatom doping for additional pseudocapacitance, which synergistically enhances the electrochemical performance of the NO-PC-based supercapacitor. The electrode delivers specific capacitance of 240 Fig at 0.3 A/g when tested in 6 mol/L KOH electrolyte, good rate capability （capacitance retention of 83.3% at 5 A/g） as well as stable cycling performance （capacitance remains -96% after 10000 cycles at 3 A/g）. The facile synthesis with unique architecture and chemistry modification offers a promising candidate for electrode material of energy storage devices.