Dear Shivaraj,
Please read the following text:
Pseudocapacitors can be considered hybrids of traditional batteries (high energy density but typically poor power output) and double layer capacitors (high power output during short bursts but low energy density). The pseudocapacitive energy
storage mechanism is different from batteries in that surface redox properties dominate the charge-transfer processes rather than normal Faradaic diffusion-controlled insertion processes. Metal oxides such as RuO2 and IrO2 act as pseudocapacitors offering exceptional power, fast charging, and longterm
stability while also affording some of the advantages of traditional secondary batteries such as reasonable storage capacity. Pseudocapacitors with moderate energy density at high charge rates over many cycles could find applications in
hybrid-electric or electric vehicles. The pseudocapacitor could be employed when fast power delivery during acceleration is required. Efficient use of renewable energies through load leveling will also require the ability to store and deliver charge rapidly. For these applications, RuO2 and IrO2 would be cost prohibitive making, TiO2 a relatively inexpensive option. By nanostructuring certain electroactive materials, this surface charge-transfer process (pseudocapacitive effect) becomes the dominant storage mechanism and can offer 10"100 times
the capacitance of a traditional carbon-based double layer capacitor. TiO2(B) is a unique anode material in that both bulk and nanostructured forms lithiate/delithiate through this pseudocapacitive mechanism, making it an attractive material for the applications noted above.
The advantages of using TiO2 as an anode in rechargeable lithium ion batteries lie in its characteristic safety and stability. Graphite is the most widely used anode material in rechargeable lithium ion batteries due in part to its low lithiation potential (∼0.1 V vs Li/Liþ) that allows for a large voltage difference between cathode an anode and reasonably high capacity. The fact that graphite lithiates at a potential near that of the Li/Liþ couple poses a problem in that the lithium electroplating can cause short circuit and thermal runaway conditions resulting in combustion of
organic electrolyte and catastrophic battery failure. Choosing an anode with a higher lithiation potential such as TiO2 (∼1.6 V vs Li/Liþ) greatly reduces the chance of this type of battery failure. Among the common polymorphs, TiO2(B)
has attracted recent attention due mainly to high energy density, but also because of the ability to nanostructure this polymorph into several distinct architectures which provides opportunities to systematically study the charge storage mechanism.
For more on this topic, please see the publication contained in the following link:
http://theory.cm.utexas.edu/henkelman/pubs/dylla13_1104.pdf
Hoping this will be helpful,
Rafik
I think that insertion of lithium in TiO2 would be carry out by using a precursor synthesis which contain Li, or use insert K by using KOH as oxidizing agent, after that insert Li by ionic exchange between K and Li.
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