[Mahirt]

it will become LiCl.. When using AP as the oxidiser it turns to HCl

[Arkcon]

So you're sure that lithium chloride is in the exhaust?  I'd defer my opinion to your knowledge of the subject, but it seems odd to me for an ionic salt to be present in hot exhaust fumes.  Maybe some other reaction occurs afterward?  Lithium oxide seems more refractory to me, and more like smoke particles.

[curiouscat]

So you're sure that lithium chloride is in the exhaust?  I'd defer my opinion to your knowledge of the subject, but it seems odd to me for an ionic salt to be present in hot exhaust fumes.  Maybe some other reaction occurs afterward?  Lithium oxide seems more refractory to me, and more like smoke particles.

Lithium Chloride just might be more stable than Lithium Oxide. I know F containing rocket oxidizers exploited a similar principle.