Abstract
Developing electrode materials with high-energy densities is important for the development of lithium-ion batteries. Here, we demonstrate a mesoporous molybdenum dioxide material with abnormal lithium-storage sites, which exhibits a discharge capacity of 1,814 mAh g−1 for the first cycle, more than twice its theoretical value, and maintains its initial capacity after 50 cycles. Contrary to previous reports, we find that a mechanism for the high and reversible lithium-storage capacity of the mesoporous molybdenum dioxide electrode is not based on a conversion reaction. Insight into the electrochemical results, obtained by in situ X-ray absorption, scanning transmission electron microscopy analysis combined with electron energy loss spectroscopy and computational modelling indicates that the nanoscale pore engineering of this transition metal oxide enables an unexpected electrochemical mass storage reaction mechanism, and may provide a strategy for the design of cation storage materials for battery systems.
Highlights
Developing electrode materials with high-energy densities is important for the development of lithium-ion batteries
1.84 mol of Li per mol of MoO2 can be stored into bulk MoO2, and 0.87 mol of Li are reversibly released from the lditehliivaetreeddbualkreMveorOsi2b.leOnchtahregeothcaepr ahcaitnyd,otfhe1,m30e8sompAorhoguÀs
The reversible Li-storage capacity of mesoporous MoO2 (6.24 mol of Li per mol of MoO2) at the first cycle exceeds the theoretical limit of Li-storage capacity through conversion reaction of MoO2 with Li (4 mol of Li per mol of MoO2), suggesting that a new Li-storage mechanism should be introduced to explain this unexpected Li-storage performance
Summary
Developing electrode materials with high-energy densities is important for the development of lithium-ion batteries. In order to improve the performance of anode parts replacing graphite (theoretical capacity of 372 mAh g À 1), there has been extensive research on developing anode materials such as transition metal oxides, silicon- or tinbased metal alloys, and related composite configurations[3,4,5,6,7,8,9,10,11] Since they follow Li-storage mechanisms such as conversion and alloying reactions with Li, which are different from the Li intercalation reaction in the graphite anode, these newly developed anode materials show higher capacity than the current anode systems. We have found that the mesoporous here gives a high Li-storage capacity
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