Huawei is likely to make the upcoming Mate 20 Pro's battery capacity and overall endurance a key point of its marketing. This has been revealed by a teaser flier that the company has been sending out, which comes with a battery pack attached. As you can see from the picture below, the implication here is that the next flagship Huawei smartphone is going to top both the Mate 10 Pro and the P20 Pro when it comes to battery capacity. Both of those models employ a 4,000 mAh cell, so expect something bigger than that (even if marginally - 4,100 mAh is technically still more so don't be...
Source: https://www.gsmarena.com/huawei_teases_biggest_battery_capacity_yet_for_the_mate_20_pro-news-32664.php