lattice energy of the Li2O is given below.

LiF (-1045 kJ/ mole)

LiCl (-864 kJ/mole)

Now you on yourself  decide that which compound has highest energy.

thank you.

 

We give more priority to charge than the size .

Hence, in li2o ,q1q2=2 but in lif q1q2= 1 ... 

So, li2o should have higher lattice energy but it's not . Why so ?