  In this work, 1272 superflares on 311 stars are collected from 22,539
solar-type stars from the second-year observation of Transiting Exoplanet
Survey Satellite (TESS), which almost covered the northern hemisphere of the
sky. Three superflare stars contain hot Jupiter candidates or ultrashort-period
planet candidates. We obtain $\gamma = -1.76\pm 0.11$ of the correlation
between flare frequency and flare energy ($dN/dE\propto E^{-\gamma}$) for all
superflares and get $\beta=0.42\pm0.01$ of the correlation between superflare
duration and energy ($T_{\text {duration }} \propto E^{\beta}$), which supports
that a similar mechanism is shared by stellar superflares and solar flares.
Stellar photometric variability ($R_{\rm var}$) is estimated for all solar-type
stars, and the relation of $E\propto {R_{\rm var}}^{3/2}$ is included. An
indicator of chromospheric activity ($S$-index) is obtained by using data from
the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) for 7454
solar-type stars. Distributions of these two properties indicate that the Sun
is generally less active than superflare stars. We find that saturation-like
feature of $R_{\rm var}\sim 0.1$ may be the reason for superflare energy
saturating around $10^{36}$ erg. Object TIC 93277807 was captured by the TESS
first-year mission and generated the most energetic superflare. This superflare
is valuable and unique that can be treated as an extreme event, which may be
generated by different mechanisms rather than other superflares.
