MXene@Sn4P3复合材料的制备及在锂离子电池负极材料中的应用研究

通过水热反应和简单的磷化处理合成了MXene@Sn4P3复合材料,材料呈现二维结构且纳米级Sn4P3颗粒在MXene表面均匀分布。利用MXene稳定的导电骨架结构,借助Sn4P3发生转化反应和合金反应两个电化学过程,在体系中贡献高比容量,最终获得了高倍率和高容量的电极材料。电化学测试结果表明:在1.0 A·g^-1的电流密度下,材料经300次循环后容量保持率高于90%,表现出优良的稳定性;并且在5.0 A·g^-1的大电流密度下,电极材料的比容量仍可达到537 mAh·g^-1,倍率性能优异,展现出极佳的电化学性能。

Degradation mechanism of tin phosphide as Na-ion battery negative electrode

The degradation mechanism of an Sn_4P_3 electrode as Na-ion battery anode was investigated by using a transmission electron microscopic observation. At the first desodiation, we confirmed that Sn nanoparticles with 6 nm in size were dispersed in an amorphous-like P matrix.Compared to this, we observed aggregated Sn particles with sizes exceeding 50 nm after the drastic capacity fading. The capacity fading mechanism was for the first time confirmed to be Sn aggregation. To improve the capacity decay, we carried out the two kinds of chargeàdischarge cycling tests under the reduced volume changes of Sn particles and P matrix by limiting desodiation reactions of Nae Sn and Na3P, respectively. The Sn_4P_3 electrode exhibited an excellent cyclability with the discharge capacity of 500 mA hg^(-1) for 420 cycles under the limited desodiation, whereas the capacity decay was accelerated under the limited sodiation. The results suggest that the Sn aggregation can be improved by the reduced volume change of the P matrix, and that it is very effective for improving anode performance of Sn_4P_3 electrode.

Affinity-Engineered Flexible Scaffold toward Energy-Dense, Highly Reversible Na Metal Batteries

The practical deployment of metallic anodes in the energy-dense batteries is impeded by the thermodynamically unstable interphase in contact with the aprotic electrolyte,structural collapse of the substrates as well as their insufficient affinity toward the metallic deposits.Herein,the mechanical flexible,lightweight(1.2 mg cm^(−2))carbon nanofiber scaffold with the monodispersed,ultrafine Sn_(4)P_(3) nanoparticles encapsulation(Sn_(4)P_(3)NPs@CNF)is proposed as the deposition substrate toward the high-areal-capacity sodium loadings up to 4 mAh cm^(−2).First-principles calculations manifest that the alloy intermediates,namely the Na_(15)Sn_(4) and Na_(3)P matrix,exhibit the intimate Na affinity as the“sodiophilic”sites.Meanwhile,the porous CNF regulates the heterogeneous alloying process and confines the deposit propagation along the nanofiber orientation.With the precise control of pairing mode with the NaVPO4F cathode(8.7 mg cm^(−2)),the practical feasibility of the Sn_(4)P_(3) NPs@CNF anode(1^(*)Na excess)is demonstrated in 2 mAh single-layer pouch cell prototype,which achieves the 95.7%capacity retention for 150 cycles at various mechanical flexing states as well as balanced energy/power densities.

微波溶剂热法合成锂离子电池负极材料Sn_4P_3/多壁碳纳米管的研究

以乙二胺为溶剂,锡粉和红磷为原料,利用微波溶剂热方法合成出Sn_4P_3/MWCNTs复合材料。利用X射线衍射和透射电子显微镜对其进行定性分析和微观形貌观察,对其作为锂离子负极材料的电化学性能进行研究。在电流密度为500 mA/g时,当Sn_4P_3/MWCNTs的质量比为3∶1时放电容量能达到517 mAh/g,Sn_4P_3/MWCNTs复合材料有望成为一种新型锂离子电池负极材料。

机械球磨法制备Sn_4P_3/RGO钠离子电池负极材料及其电化学性能研究

以红磷、锡粉和还原氧化石墨烯作为主要反应物,利用机械球磨法成功合成磷化锡/还原氧化石墨烯(Sn_4P_3/RGO)复合材料,并用作钠离子电池的负极材料.采用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)、蓝电测试系统和电化学工作站对所获得的样品粉末进行物相、微观形貌以及电化学性能表征.与纯相Sn_4P_3相比, Sn_4P_3/RGO复合材料作为钠离子电池负极材料展示出较为优异的电化学性能.

Sn_(4)P_(3)nanoparticles confined in multilayer graphene sheets as a high-performance anode material for potassium-ion batteries

Phosphorus-based anodes are highly promising for potassium-ion batteries(PIBs)because of their large theoretical capacities.Nevertheless,the inferior potassium storage properties caused by the poor electronic conductivity,easy self-aggregation,and huge volumetric changes upon cycling process restrain their practical applications.Now we impregnate Sn_(4)P_(3)nanoparticles within multilayer graphene sheets(Sn_(4)P_(3)/MGS)as the anode material for PIBs,greatly improving its potassium storage performance.Specifically,the graphene sheets can efficiently suppress the aggregation of Sn_(4)P_(3)nanoparticles,enhance the electronic conductivity,and sustain the structural integrity.In addition,plenty of Sn_(4)P_(3)nanoparticles impregnated in MGS offer a large accessible area for the electrolyte,which decreases the diffusion distance for K^(+)and electrons upon K^(+)insertion/extraction,resulting in an improved rate capability.Consequently,the optimized Sn_(4)P_(3)/MGS containing 80 wt%Sn_(4)P_(3)(Sn_(4)P_(3)/MGS-80)exhibits a high reversible capacity of 378.2 and 260.2 m Ah g;at 0.1 and 1 A g^(-1),respectively,and still delivers a large capacity retention of 76.6%after the 1000th cycle at 0.5 A g^(-1).

磷化镍助催化剂修饰石墨相氮化碳促进光催化重整杨树叶制氢性能

以双氰胺(C_(2)H_(4)N_(4))为原料,采用直接热聚合法制备石墨相氮化碳(g-C_(3)N_(4));以六水合氯化镍(NiCl_(2)·6H_(2)O)和赤磷(P4)为原料,采用简易的水热法将磷化镍(Ni_(2)P)助催化剂负载到二维g-C_(3)N_(4)表面.通过X-射线衍射(XRD)、红外(IR)、透射电子显微镜(TEM)、扫描透射电子显微镜(STEM)、N_(2)吸/脱附、固体紫外漫反射(UV-Vis DRS)、荧光(PL)等,表征所合成催化剂的化学结构、微观形貌及光电性质;以原生生物质杨树叶为牺牲剂,在碱性条件下(3 M NaOH)研究催化剂的光催化重整制氢性能.结果表明:单一的g-C_(3)N_(4)材料无法实现光催化重整制氢,而少量的Ni_(2)P助催化剂负载后可以实现光催化重整制氢;当Ni_(2)P助催化剂负载量为4%(质量分数),杨树叶质量浓度为0.2 g/L时,催化剂展现出最佳的光催化重整制氢活性,平均产氢速率可达3.38μmol/(g·h).

SnP entangled by carbon nanotube networks as anode for pseudocapacitive half/full battery

Due to the lower operating voltage and higher theoretical specific capacity,tin phosphide is considered a class of materials with prospects as an anode material for lithium-ion batteries(LIBs).Among them,tin monophosphide has attracted people's attention due to its unique layered structure.Unfortunately,because of the challenging synthesis method and metastable nature,the application of SnP is limited.In this work,tin phosphide/carbon nanotubes(SnP/CNTs)are prepared by controlling the nucleation and adjusting the ratio of phosphorus/carbon using carbon nanotube as initiator.Sn-MOF is used as a template to make the morphology of SnP more evenly,and carbon nanotubes can also be used as a conductive network to increase the speed of electron transmission.As an anode material for LIBs,SnP/CNTs reveals superior rate performances(reversible capability of 610 mA·h·g^(-1)at 2000 mA·g^(-1)).The full-cell was assembled and tested,after 50 cycles at 0.1 C,the capacity can maintain 292 mA·h·g^(-1),and its capacity retention rate can reach 80.5%.After 230 cycles,its capacity can maintain at around 223 mA·h·g
1.In addition,SnP/CNTs materials exhibit 89%pseudocapacitance contribution upon cycling,which indicates the robust Lit storage and satisfactory fast-charging capability.Hence,SnP/CNTs suggests a promising anode material for energy storage system.