Owing to its high theoretically gravimetric lithium storagecapacity of 782 mAh/g which is more than twice that of thecurrently commercialized graphite (372 mAh/g) and low potentialof lithium ion intercalation, SnO2 is regarded as one of the mostpromising candidates for anode materials.1 It is well establishedthat there are two-step reactions involved in the SnO2-based workingelectrode.2 The first irreversible reaction is responsible for severecapacity loss in the first few cycles which actually results from theformation of electrochemically inactive Li2O. The second one isreversible with lithium ions repeatedly stored and released betweenalloying and dealloying processes. However, an intrinsically induceddrastic volume change causes a so-called pulverization problemwhich blocks the electrical contact pathways in the electrode andleads to rapid deterioration in capacity. To enhance the cyclabilityof the electrode, hybridizing SnO2 with carbon is effective, but thisapproach sacrifices the capacity itself due to the introduction ofcarbon and is usually complicated in fabrication.3 It is suggestedthat if single SnO2 was used as an active material, it should be ina nanometer-sized frame to shorten the pathway lengths of thelithium ion and should possess interior hollow spaces to accommodatelarge volume change.4 Herein, we report highly porous SnO2nanometer-sized sheets synthesized from a hydrothermal reaction.
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