Enhanced electrochemical properties of Mg2+ doped Li2Na2Ti6O14 anode material for lithium-ion batteries. (1st April 2016)

• Record Type: Journal Article
• Authors: Lao, Mengmeng; Qian, Shangshu; Yu, Haoxiang; Yan, Lei; Li, Peng; Lin, Xiaoting; Long, Nengbing; Shui, Miao; Shu, Jie
• Is Part Of: Electrochimica acta. Volume 196(2016)
• Page Start: 642
• Page End: 652
• Publication Date: 2016-04-01
• Subjects: Lithium sodium titanate -- Magnesium doping -- Electrochemical property -- In-situ structural evolution -- Lithium-ion batteries; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2016.03.035
• Languages: English
• ISSNs: 0013-4686

Abstract

Graphical abstract: Highlights: Substitution of Li + by Mg 2+ is successfully performed for Li2 Na2 Ti6 O14 . Mg 2+ doping enhances the electronic/ionic conductivity of Li2 Na2 Ti6 O14 . Li1.95 Mg0.05 Na2 Ti6 O14 shows improved lithium storage capability. Lithiation process in Li1.95 Mg0.05 Na2 Ti6 O14 is studied by in-situ XRD. Abstract: A series of Mg 2+ doped Li2 Na2 Ti6 O14 in the form of Li2-x Mgx Na2 Ti6 O14 (x = 0.0, 0.05, 0.1, 0.15, 2.0) are successfully synthesized via a solid-state method. Phase structure and surface morphology analyses show that all samples maintain high purity and low dose of Mg 2+ doping does not change the crystal structure and surface morphology of Li2 Na2 Ti6 O14 . According to the Rietveld refinement result, it is known that Mg 2+ takes the tetrahedral 8i sites shared with Li + in the structure. Galvanostatic charge/discharge tests demonstrate that Li1.95 Mg0.05 Na2 Ti6 O14 exhibits higher reversible capacity (264.6 mAh g −1 ) and better cycling performance (capacity retention of 82.7% after 50 cycles) than other materials. Even cycled at high current density of 500 mA g −1, Li1.95 Mg0.05 Na2 Ti6 O14 still provides the specific capacity of 167.4 mA g −1 after 100 cycles, indicating that low dose of Mg 2+ doping can effectively improve the lithium storage capability of Li2 Na2 Ti6 O14. The enhanced electrochemical properties are contributed to the improved electronic conductivity and ionic diffusion coefficient of Li2 Na2 Ti6 O14 via Mg 2+ doping. Besides, the lithiation/delithiation behavior of Li1.95 Mg0.05 Na2 Ti6 O14 is also studied by homemade in-situ X-ray diffraction device, which reveals that Li1.95 Mg0.05 Na2 Ti6 O14 exhibits high structural and electrochemical reversibility as lithium storage material.