The development of the G7e(TII) torpedo (note the correct nomenclature...) wasn't done in a specific year. It's a long story and the process went on for many years, starting with Siemens' first electric propulsioned torpedo ca 1920. It also involved a brief collaboration with the spanish navy and the firm Echevarrieta in Cadiz (they were supposed to develop and manufacture both the G7a(TI) and the G7e(TII)). That collaboration stranded as the firm went bankrupt (also, the Spanish navy declared no interest in electric torpedoes).
Kriegsmarine turned to Sweden for further collaboration and the actual G7e-development was a collaboration between Siemens-Schuckertwerke and the swedish firm AFA-Tudor (to add more complications, the final testing of the G7e was actually done at the Whitehead-factory in Fiume, Italy).

The first 12 G7e torpedoes were delivered from AFA-Tudor in april 1934, and the first order for series-production of 30 torpedoes was given to the german firm Julius Pintsch KG in august with delivery 7 months later. The G7e-design was declared operational and ready for start of high-volume production in october 1934.

The Type VII A uboats were the first to be equipped with the new G7e(TII) torpedo, as the torpedo was fielded in 1936.