College of Science, Northeast Dianli University , Jilin 132012, P. R. China.
Institute for Applied Materials (IAM), Karlsruhe Institute of Technology (KIT) , D-76344 Eggenstein-Leopoldshafen, Germany.
ACS Appl Mater Interfaces. 2017 Feb 8;9(5):4709-4718. doi: 10.1021/acsami.6b14196. Epub 2017 Jan 30.
A carbon-coated MgTi(PO) polyanion material was prepared by the sol-gel method and then studied as the negative electrode materials for lithium-ion and sodium-ion batteries. The material showed a specific capacity of 268.6 mAh g in the voltage window of 0.01-3.0 V vs Na/Na. Due to the fast diffusion of Na in the NASICON framework, the material exhibited superior rate capability with a specific capacity of 94.4 mAh g at a current density of 5A g. Additionally, 99.1% capacity retention was achieved after 300 cycles, demonstrating excellent cycle stability. By comparison, MgTi(PO) delivered 629.2 mAh g in 0.01-3.0 V vs Li/Li, much higher than that of the sodium-ion cells. During the first discharge, the material decomposed to Ti/Mg nanoparticles, which were encapsulated in an amorphous SEI and LiPO matrix. Li ions were stored in the LiPO matrix and the SEI film formed/decomposed in subsequent cycles, contributing to the large Li capacity of MgTi(PO). However, the lithium-ion cells exhibited inferior rate capability and cycle stability compared to the sodium-ion cells due to the sluggish electrochemical kinetics of the electrode.
一种碳包覆的 MgTi(PO) 多阴离子材料通过溶胶-凝胶法制备，并作为锂离子和钠离子电池的负极材料进行了研究。该材料在 0.01-3.0 V vs Na/Na 的电压窗口下表现出 268.6 mAh g 的比容量。由于钠离子在 NASICON 骨架中的快速扩散，该材料表现出优异的倍率性能，在 5A g 的电流密度下具有 94.4 mAh g 的比容量。此外，经过 300 次循环后，容量保持率达到 99.1%，表现出优异的循环稳定性。相比之下，MgTi(PO) 在 0.01-3.0 V vs Li/Li 下提供了 629.2 mAh g 的比容量，远高于钠离子电池。在首次放电过程中，该材料分解为 Ti/Mg 纳米颗粒，被包裹在非晶态 SEI 和 LiPO 基质中。锂离子储存在 LiPO 基质中，SEI 膜在随后的循环中形成/分解，这导致了 MgTi(PO) 具有较大的锂离子容量。然而，与钠离子电池相比，锂离子电池的倍率性能和循环稳定性较差，这是由于电极的电化学动力学缓慢所致。
