PWM nonlinear behavior for Grove - I2C Motor Driver (TB6612FNG)

There is a lot of choices!

If you want continue to use Grove IIC interface, you can try Grove - I2C Mini Motor Driver

If you are using Arduino, you can try Motor Shield V2.0 for Arduino

If you want to use PWM to driect control on your own, try MAKER DRIVE - MIX1508 H-Bridge Motor Driver