Our goal is to develop and apply a new biologically inspired, low cost, low temperature approach to make nanocomposites with exceptionally high power and stability as anodes and cathodes for lithium ion batteries. In addition to the near-term application of the results of these studies for the improvement of batteries and related energy technologies, the broader impact of this research includes a deeper fundamental understanding of the factors governing the control of synthesis, assembly and performance of a wide range of semiconductors and other valuable inorganic materials, to enable their more economical and more efficient use for energy technologies including energy harvesting, transduction and storage.
Figure: (A) TEM images of nanocrystals of Sn grown catalytically in situ in the compliant and conductive graphitematrix. EDX (energy dispersive X-ray) mapping of Sn confirms uniformity of dispersion; crystallinity and purity of both theSn and graphite are confirmed by XRD and Raman analyses. (B) Comparison of electrochemical performances of thecomposite anode (15% Sn) with that of graphite alone, illustrating the higher capacity and superior cyclability of thecomposite. Vapor-diffusion mediated, kinetically controlled catalysis are required, as drop-wise addition of the catalyst failsto yield stability resulting from in situ growth of Sn nanocrystals inside the interstices of the compliant graphite matrix. (C) High power-density of Sn-graphite composite (red), relative to that of the starting graphite and current commercial anode.“C” is a measure of the rate of cyclical discharging and recharging. Note full reversibility after discharge at the exceptionallyhigh rate of 50C. (D, E) Nanocrystalline LiM2O4 in MW-CNT matrices exhibiting high crystallinity and exceptionalintermixing of the 2 phases to yield high power, high voltage cathode. (F) Exceptionally high power of cathode performanceof nanocomposite shown in D & E; full reversibility after complete discharge at very high power indicates lack of damage(confirmed by EM and XRD, not shown). Inset shows low hysteresis and flat voltage-vs.-capacity curves, evidence ofunimodal lithiation/de-lithiation resulting from low defect density of nanocrystallites. (G) Combination of our high-poweranode and cathode yields 11-X higher power than present commercial lithium ion batteries.