Please note that the half reaction mentioned is Ca+. Mendelyev table will make mention of only one oxidation state namely Ca++.
This means the half reaction is very exotic and Ca+ is not stable at all.
The late Prof. Van Vaeck told me he observed Ca+ (at m/z 20) in dynamic SIMS but since transmission times of secondary ions to the detector are in the order of nanoseconds this might well be possible.
E0 of Ca2+ + 2e- = Ca is -2.869 V (compared to standard hydrogen cell).
Pretty decent still but... earth alkali salts are not as solluble as alkali (Li, Na, K...) salts.
There are however batteries with Ca salts.
I also want to mention that electronegativity is used in basic chemistry to make a difference between ionic bonding or covalent bonds and this has nothing to do with the (arbitrary relative scale (compared to standard hydrogen cell)) half reaction table.
Areyoukiddingme knows what he is talking about and mentioned the essence.