  We show that under the effect of an external electric field and a gradient of
chemical potential, a topological electric current can be induced in Weyl
semimetals without inversion and mirror symmetries. We derive analytic
expressions for the nonlinear conductivity tensor and show that it is nearly
quantized for small tilting when the Fermi levels are close to the Weyl nodes.
When the van Hove point is much larger than the largest Fermi level, the band
structure is described by two linearly dispersing Weyl fermions with opposite
chirality. In this case, the electrochemical response is fully quantized in
terms of fundamental constants and the scattering time, and it can be used to
measure directly the topological charge of Weyl points. We show that the
electrochemical chiral current may be derived from an electromagnetic action
similar to axion electrodynamics, where the position-dependent chiral Fermi
level plays the role of the axion field. This posits our results as a direct
consequence of the chiral anomaly.
