China's Silicon‑Carbon Phone Batteries Face Capacity Lock, Xiaomi Launches New Automotive Battery System

Chinese smartphone makers have increasingly adopted silicon‑carbon batteries that can be rated at 8,000 mAh to 10,000 mAh. Independent testing revealed that the usable capacity of such phones often falls short of the advertised figure, averaging about 87 % of the nominal rating. The shortfall, termed “capacity lock,” is attributed to manufacturers deliberately reserving a portion of the battery’s capacity to protect the silicon anode from over‑charging, to accommodate low‑voltage power‑supply constraints, and to manage hardware‑design trade‑offs. Huawei’s recent low‑voltage adaptations illustrate how design changes can unlock additional capacity.

Separately, Xiaomi Corp. announced the “Longjia” battery system for its automotive division. The system integrates Xiaomi’s product definition, battery‑pack and cell design, and end‑to‑end quality control, featuring shadow‑factory oversight, X‑ray/CT/AI inspections, and a unique electronic ID for each cell. The Longjia system will power the Xiaomi Pengcheng N70 and N90 electric‑vehicle models, marking the company’s entry into systematic automotive‑battery solutions.