About charging with charger over ampe

Hi,

I wonder that if I use power adapter but the ampe is higher than standard, isn't it problem?

For example, Standard Power Adapter output for iPhone is 5V-1A but I use Power Adapter output 5V-2.1A, is it problem?

I think the time for charging is faster but I don't know the life of battery is reduce or normal.

So I would like to make this question to know from who has experience about this.

Thanks and expect to receive the knowledge.

Hieu.