| Summary: | 碩士 === 國立清華大學 === 材料科學工程學系 === 106 === Abstract
This dissertation focuses on the anode materials of lithium-ion batteries (LIBs).
Research in batteries has widely developed since Sony Corporation announced a brand-new energy storage device called lithium-ion battery 26 years ago (1991). Because of the light weight, outstanding energy density, and well cycling stability, LIBs are up to grade for a wide range of portable devices and electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in electric vehicles (PEV). Researchers have aggressively studied lower-cost, higher-storage capacity, and safer electrode materials. Graphite is the most widely used commercial anode material, but its low theoretical capacity (372 mA h g-1) restricts the application in high energy density demands. Lithium-titanium–based Li-insertion materials possess excellent cycle life and low-time-consuming yet suffer from low capacity (< 200 mA h g-1) and high electrical resistivity. Silicon-based and transition-metal-oxide-based conversion materials owe over 1000 mA h g-1 capacity, but severe volume changes during charging/discharging processes leads to vicious capacity fading.
The discovery of C60, as known as fullerene, in 1985 have brought us to a new horizon in the chemistry of highly symmetric molecules. Herein, we report Mo-V and Mo-Fe-mixed Keplerate polyoxometalates (POMs), a kind of Fullerene-like metal oxide clusters, which was synthesized through a simple solution process as anode material for LIBs. Because of diverse oxidation states of Mo, V, and Fe (Mo2+~Mo6+, Fe2+~Fe8/3+ and V2+~V5+), the multiple redox centers within Mo-V and Mo-Fe mixed POMs during charge-discharge processes result in high capacity and excellent stability individually without any supporting additives and carbonaceous materials.
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