科研之友
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摘要
Stoichiometric LiMn2O4 has been synthesized using a one-pot resorcinol -formaldehyde route. The resulting material is composed of nanoparticles fused together, thus forming a porous morphology. The material when used as a cathode in a lithium battery exhibits, at 30 degrees C, an initial capacity of 131 mA center dot h g(-1) retaining a capacity of 118 mA center dot h g(-1) after 200 cycles (99.95% capacity retention per cycle) and at 50 degrees C an initial capacity of 132 mA center dot h g(-1) retaining 110 mA center dot h g(-1) after 200 cycles (99.92% capacity retention per cycle) all at a rate of C/2 (where 1C = 148 mA g(-1)), with no evidence of structural degradation. Rate capability is demonstrated by retention of 90% of the capacity at a rate of 40C compared with the capacity at C/5 rate. Cycling at a rate of 10C is associated with nearly 100% power retention after 1000 cycles (initial value of 5840 W kg(-1) (of LiMn2O4) dropping to 5828 W kg(-1) after 1000 cycles). Differences in the capacity retention on cycling between the material reported here and conventionally synthesized bulk LiMn2O4 Or nanoparticle LiMn2O4 synthesized by a different sot-gel route also yielding interconnected nanoparticles are reflected in superior structural stability, lower Mn dissolution, and relatively invariant ac impedance of our nano-LiMn2O4. Such results suggest that the material prepared using the resorcinol-formaldehyde route may possess a stabilized surface that inhibits dissolution.
- 出版日期2008-9-9
