recharging zinc-carbon batteries? (if an "AA R6P" is a zinc-carbon anyway)
Alkaline batteries have a degree of rechargeabilityy - improved by charging with "dirty DC" - pulsing DC with a proportion of discharge per mains cycle. Cycles are limited and capacity is also low. Not ideal or anywhere as good as a proper rechargeable battery.

Carbon zinc (non alkaline) are AFAIK not as good as Alkaline at being recharged.

It is a regrettably common occurrence for items made in China to cut corners or to fraudulently use components that have no chance of meeting the claimed performance. It is quite likely that your battery is in this category. Some equipment ios wrongly labelled and does actually meet the intended spec = but this is less common. 

Here are some R6P AA batteries advertised on Alibaba - they are Manganese Zinc - not rechargeable.