Molar mass Li2CO3 = 73.89 g/mol
Molar mass Li = 6.94g/mol Li = 6.94*2 = 13.88g
% LI = 13.88/73.89*100 = 18.78% perfectly correct.
Answer:
The biggest risk with recharging alkaline batteries is leakage. As you probably know, alkaline batteries leak even under normal circumstances. Internal off gassing, made worse by heat, creates pressure that can breach battery seals. Therefore, the risk of leakage is an even bigger risk when recharging.
One major characteristic they have in common is they are metals.