Xiaomi has confirmed that it will pair the Redmi K40 series with a 4,520 mAh battery, a downgrade from last year's Redmi K30 Pro. The company has teased more details about its upcoming 'double flagship' smartphones too, including a special Damascus steel-inspired design.
https://www.notebookcheck.net/Xiaomi-details-a-battery-downgrade-for-the-Redmi-K40-Pro-a-Damascus-steel-inspired-design-and-a-100-mm-equivalent-macro-camera-ahead-of-February-25-announcement.523460.0.html