An apparatus for mixing and agitating electrode materials for a secondary battery includes: a vessel configured to accommodate materials for a secondary battery, the vessel including a transparent material such that an inside of the vessel is visible from the outside; an agitator configured to rotate and revolve within the vessel to mix and agitate the materials; a disperser configured to disperse the materials; and a driver housing accommodating driving parts that operate the agitator and the disperser.

Disclosed is a hydrogen recirculation ejector for fuel cells including a recirculation line configured to recirculate residual hydrogen gas discharged from a fuel cell stack configured to generate electricity using air and hydrogen gas supplied thereto to an inlet of the fuel cell stack and an ejector including a nozzle installed on the recirculation line, the nozzle being configured to supply new hydrogen gas, a venturi tube configured to mix the hydrogen supplied from the nozzle and the recirculated hydrogen with each other, and a diffuser configured to supply the mixed hydrogen gas to the fuel cell stack, wherein the nozzle includes a hydrogen introduction portion, a ring-shaped inner wall, a ring-shaped outer wall, a ring-shaped front end wall, and a ring-shaped rear end wall, and wherein the thickness of the inner wall and/or the outer wall is gradually increased with increasing distance from the hydrogen introduction portion.

A slurry storage device that stores an aqueous slurry containing a high nickel material prepared by a dispersion device which mixes a powder and a solvent, the device includes a holding unit that holds the aqueous slurry, and a pH value rise suppressing unit that suppresses a rise in a pH value of the aqueous slurry.

An apparatus for reducing vibration of a mixer used in manufacturing of an electrode slurry includes a rotation roller member between an inner vessel and an outer vessel extending around the inner vessel of the mixer and a damping cylinder on the outer vessel and configured to absorb the vibration transferred through the rotation roller member to reduce the vibration.