There may be many reasons for slow charging, such as the charging cable may be damaged, the charger power is not enough, the phone itself has software problems, battery aging and so on.
To solve this problem, you can try to use the original charging cable and adapter to ensure that the charger power is sufficient, preferably using a charger of 2.4A or above. At the same time, you can also try to reduce the use of the phone when charging to avoid affecting the charging speed. In addition, you can try to update the mobile phone system or carry out a deep battery charge and discharge to solve the problem of software or battery aging. If the above methods can not solve the problem, it is best to contact the mobile phone brand customer service for further investigation and solution.