The reaction between TiO2(anatase) and Li metal takes place in steps to first form Ti+3 and Li+1 ions as the following reaction is highly spontaneous :

Ti+4 (from TiO2) +4Li(s) ------- Li+1 +Ti+3 Delta E0=2.96V

The Li ions, thus formed moves into one of the structural voids undermeath the top layer surface and stop the further reaction as Li+1 do not leave the interstial sites. So the further reaction, i.e. formation of the +2, +1 and zero (Ti metal) is hindered.[ In some cases fomation of Ti+2 has been reported (when (Li/Ti = 0.28) ].

As regards to the reaction with TiSnSb, it undergoes a conversion/ disproportionation process leading simultaneously to the formation of Li-Sb andLi-Sn intermetallics; leaving Ti metal behind because Ti being more electropositive than Sn/Sb, cannot form Li-Ti intremetallic.

thanks for your reply.

If I understand correctly then you are saying the reason for the low effective number of Lithium reacted with Ti within the TiO2 is due to a sterical blocking. Are you saying that once tio2 has reacted on the surface a further pentration into the bulk is blocked?

If so why then is it that even in highly nanostructured TiO2 an insertion above 1 Li / TiO2 is seldomly found?

From a crystallographic viewpoint there are 10 crystallographic sites (4*A1+4*A2+2*C) for Li intercalation within a unit cell containing 8 Ti leading to a max crystallogrpahic stochiometry of Li1,25TiO2. Such high number of lithium intercalation is experimentally never observed (to the best of my knowledge).

I still dont see why Ti+IV cant be reduced lower than Ti+III upon reaction with Li in the TiO2. I would appreciate if you could further develop on this.