The atomic number of lithium (Li) is 3.
Thus, its electronic configuration is : 1s^{2}2s^{1}.
Lithium cation is formed when lithium atom loses one of its valence electon.
Hence, [Li+] = 1s^{2}
∴ Lewis dot structure of Li is :
Li ·
and lewis dot structure of Lithium cation is:
[Li]+