  The recently-discovered giant exoplanet HR5183b exists on a wide,
highly-eccentric orbit ($a=18$\,au, $e=0.84$). Its host star possesses a common
proper-motion companion which is likely on a bound orbit. In this paper, we
explore scenarios for the excitation of the eccentricity of the planet in
binary systems such as this, considering planet-planet scattering, Lidov-Kozai
cycles from the binary acting on a single-planet system, or Lidov-Kozai cycles
acting on a two-planet system that also undergoes scattering. Planet-planet
scattering, in the absence of a binary companion, has a $2.8-7.2\%$ probability
of pumping eccentricities to the observed values in our simulations, depending
on the relative masses of the two planets. Lidov-Kozai cycles from the binary
acting on an initially circular orbit can excite eccentricities to the observed
value, but require very specific orbital configurations for the binary and
overall there is a low probability of catching the orbit at the high observed
high eccentricity ($0.6\%$). The best case is provided by planet-planet
scattering in the presence of a binary companion: here, the scattering provides
the surviving planet with an initial eccentricity boost that is subsequently
further increased by Kozai cycles from the binary. We find a success rate of
$10.4\%$ for currently observing $e\ge0.84$ in this set-up. The single-planet
plus binary and two-planet plus binary cases are potentially distinguishable if
the mutual inclination of the binary and the planet can be measured, as the
latter permits a broader range of mutual inclinations. The combination of
scattering and Lidov-Kozai forcing may also be at work in other wide-orbit
eccentric giant planets, which have a high rate of stellar binary companions.
