| In recent years,rechargeable lithium-ion batteries?LIBs?have been widely used in mobile phones,digital camera and other electronic products,showing great prospect in power electric vehicles?EVs?or hybrid electric vehicles?HEVs?.However,graphite as the commercially used anode material cannot meet the requirement and expectations for large high capacity,high power lithium ion battery,due to its low theoretical capacity and high lithium insertion barrier.In order to develop a new generation of high performance lithium ion battery,various anode materials including new carbon materials?carbon tube,carbon fiber and graphene?,metal oxides?Co Ox and Mn Ox?and metal sulfides(Mo S2 and Sn S2)have been widely investigated in LIBs.Many studies have shown that metal oxides and metal sulfides electrode materials although has great specific capacity,shows excellent lithium storage capacity,but also has significant shortcomings in practical application.For example,the low electronic conductivity affected its rate capability and cycling stability,and the drastic volume changes during the repeated lithium insertion/extration processes,which results in anode materials from current collectors and rapid capacity fading upon cycling.The main contents and results of this thesis are as follows:1. The Mo S2 nanosheets were prepared by a lithium intercalation and exfoliation methods.The morphology and structure of the Mo S2 nanosheets are characterized by SEM,TEM,XRD,Raman,XPS and AFM.The results showed that the methods of prepared the Mo S2 nanosheets with a single or few layer.2.Mo S2/RGO composite material have been synthesized via Electrostatic spraying and Light reduction approaches.When using as an anode materialin lithium-ion battery,the Mo S2/RGO nanosheets exhibit superior electrochemical performance compared to the Mo S2 nanosheets,including high specific capacity(1242.7 m Ah g-1 at 0.1 A g-1),excellent rate capability(533.7 m Ah g-1 at 2.0 A g-1 and361.6 m Ah g-1 at 5.0 A g-1),and good cycling stability(872.8 m Ah g-1 after 100cycles at 0.1 A g-1and 671.4 m Ah g-1 at 2.0 A g-1 after 1000 cycles).3.Mn O/CNFs@G nanofiber membranes have been synthesized via electrostatic spinning and ambient pressure chemical vapor deposition?APCVD?method.When the membranes directly used as binder-free anode for lithium-ion batteries,the materials showed excellent electrochemical performance:under a current density of 5A g-1,it delivered a high reversible capacity of 490.7 m Ah g-1 after 1000 cycles,and367.4 m Ah g-1 after 5000 cycles at a high current density of 10 A g-1 with a significant coulombic efficiency of 99.8%. |
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