I would use the Lenco or Tweco equivalent to connect the positive lead. You wont have to worry about shorting it out due to scraping off the insulation. It is also quick to disconnect if needed and provides a positive electrical connection.
To splice cable, I use a copper water pipe T of the right size. I clean and flux it and the cable ends, push the cables in each end of the fitting, and add lead through the T, heating with a torch until the pipe is full!
Once cool, I grind the T off the fitting and add tape and shrink wrap over the pipe fitting.
It's a permanent splice that I've NEVER had fail...
SR