Income taxes - Changes to valuation allowance (Details) |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2025
CNY (¥)
|
Dec. 31, 2025
USD ($)
|
Dec. 31, 2024
CNY (¥)
|
|
| Income taxes | |||
| Balance at beginning of the year | ¥ (759,896,561) | $ (108,663,763) | ¥ (1,008,969,418) |
| Additions | (65,445,776) | (9,358,620) | (85,036,821) |
| Reversals | 219,034,475 | 31,321,513 | 334,109,678 |
| Balance at end of the year | ¥ (606,307,862) | $ (86,700,870) | ¥ (759,896,561) |