Only the company's own marketing materials, but as a data point six years ago they partnered with a Chinese phone manufacturer to create a device with an absurd

Only the company's own marketing materials, but as a data point six years ago they partnered with a Chinese phone manufacturer to create a device with an absurd (at the time) 5800mAh battery: https://www.gizchina.com/2015/04/27/bluboo-x550-will-feature-ampirus-battery-and-mediatek-pump-express-plus-for-super-fast-charging/ https://www.gizchina.com/2015/04/27/bluboo-x550-will-feature... They've made some improvements since, but the exact parameters haven't been disclosed.