BEIJING (Reuters) -Chinese electric vehicle maker Nio has completed 40 million battery swaps so far, CEO William Li said on Thursday, replacing depleted batteries with fully charged packs, rather than plugging the vehicle into a charging point.

Nio is one of a handful of EV makers betting on battery swapping as a major power option for EVs. It currently has 2,382 battery swapping stations and 21,652 public charging stations, according to Li. The company currently buys most of its batteries from CATL.

Swapping could help to ease the strain on power grids at peak times when drivers recharge, but industry analysts and executives expect it would only become feasible if batteries become more standardised. While some have criticised battery swapping stations as a costly investment, Nio argues they can be both a quicker solution to powering up EVs and an energy storage facility to improve grid stability.

The most important issue facing the company's battery swapping and public charging stations was battery life, Nio CEO Li said on Thursday. The company has directed significant investment in terms of research and development to solve this problem, he added. Nio has for years pursued a strategy of developing end-to-end technologies for EVs including advanced manufacturing, batteries, autonomous driving and chips. But Nio is now working to reassure investors concerned it has taken on too much after also ventured into areas such as smartphone manufacturing and battery swapping in recent years, and invested heavily in drawing top talent and facilities. The loss-making EV maker has been looking to improve profitability. It has trimmed its workforce and deferred long-term investments to improve efficiency and reduce costs in the face of growing competition, which began after U.S. auto maker Tesla kicked off a price war last year. Reuters reported in December that Nio planned to spin off its battery manufacturing unit, according to two people with knowledge of the matter, as part of the efforts by the company to turn profitable, reduce costs and improve efficiency.