Accounts receivable and allowance for credit losses (Details 1) |
6 Months Ended | 12 Months Ended | |
|---|---|---|---|
|
Jun. 30, 2025
USD ($)
|
Jun. 30, 2025
CNY (¥)
|
Dec. 31, 2023
CNY (¥)
|
|
| Credit Loss [Abstract] | |||
| Beginning balance | ¥ 3,951,391 | ||
| Addition | |||
| Recovery | (3,951,391) | ||
| Ending balance | |||