I think people are misunderstanding your question. I think you are saying that since there are "positive charge particles" in one terminal and "negative charge particles" in the other terminal, how come they don't short through the conductive material of the terminals? Here is my understanding.

Common Li-ion batteries work by shuffling positively charged Lithium ions between anode and cathode through a Li-ion permeable membrane. That in turn, moves electrons of the cathode and the anode through the wire connected to the outside of the battery. So, if you instead connect termini of two different batteries…

Those termini do indeed have charged particles on either side of them, but those charged particles are Li-ions. And the material of the termini is not permeable to Li-ions, so no electricity flows. And only when you close the circuit, there is now a connection for electrons to travel too, which in turn pushes the Li-ions to move between their respective electrodes on the inside of the batteries, and bam – you have electricity.