Segment information (Details 1) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Assets	$ 255,007,507	$ 220,264,538
Lithium Batteries [Member]
Segment Reporting Information [Line Items]
Total Assets	207,643,314	171,881,450
Ni-MH Batteries [Member]
Segment Reporting Information [Line Items]
Total Assets	$ 47,364,193	$ 48,383,088