A multi-stage charging device for a fuel cell comprising: a shaft that is supported for rotation about an axis ; a first compressor wheel and a first compressor housing that cooperate to define a first compressor stage , the first compressor wheel being fixed on the shaft ; a second compressor wheel and a second compressor housing that cooperate to define a second compressor stage , the second compressor wheel being fixed on the shaft , the second compressor housing defining a radial inlet , a shroud member and a volute member , the radial inlet being fluidly connected to a diffuser section and the volute member defining a volute passage therein that extends about the axis ; a turbine wheel and a turbine housing that cooperate to define a turbine section , the turbine wheel fixed on the shaft in a back-to-back arrangement with the second compressor wheel , the turbine housing defining a volute inlet member with a circumferential passage and a radial passage formed therein; a divider member comprising a plate that is positioned between the turbine housing and the second compressor housing , the divider member defining a boundary for the turbine section and the second compressor stage , wherein a first surface of the plate defines a portion of the radial passage and the circumferential passage and wherein a second surface of the plate defines a portion of the diffuser section and the volute passage ; a motor that is disposed between the back-to-back arrangement and the first compressor wheel ; and wherein the turbine wheel is configured to be driven in rotation by exhaust from a fuel cell to assist the motor . a shaft that is supported for rotation about an axis ; a first compressor wheel and a first compressor housing that cooperate to define a first compressor stage , the first compressor wheel being fixed on the shaft ; a second compressor wheel and a second compressor housing that cooperate to define a second compressor stage , the second compressor wheel being fixed on the shaft , the second compressor housing defining a radial inlet , a shroud member and a volute member , the radial inlet being fluidly connected to a diffuser section and the volute member defining a volute passage therein that extends about the axis ; a turbine wheel and a turbine housing that cooperate to define a turbine section , the turbine wheel fixed on the shaft in a back-to-back arrangement with the second compressor wheel , the turbine housing defining a volute inlet member with a circumferential passage and a radial passage formed therein; a divider member comprising a plate that is positioned between the turbine housing and the second compressor housing , the divider member defining a boundary for the turbine section and the second compressor stage , wherein a first surface of the plate defines a portion of the radial passage and the circumferential passage and wherein a second surface of the plate defines a portion of the diffuser section and the volute passage ; a motor that is disposed between the back-to-back arrangement and the first compressor wheel ; and wherein the turbine wheel is configured to be driven in rotation by exhaust from a fuel cell to assist the motor . <EOS>