2 aligned axes

var graphinstance = new Graph( domGraph, {

  dblclick: {
    type: 'plugin',
    plugin: 'zoom',
    options: {
      mode: 'total'
    }
  },

  plugins: {
    'zoom': {
      zoomMode: 'x'
    },
    'drag': {}
  },

  pluginAction: {
    'drag': {
      shift: true,
      ctrl: false
    },
    'zoom': {
      shift: false,
      ctrl: false
    }
  }

} );
var axisProperties = {
    primaryGrid: false,
    secondaryGrid: false,
    nbTicksPrimary: 5
  },
  xAxis2 = graphinstance.getXAxis( 1, axisProperties ),
  xAxis = graphinstance.getXAxis( 0, axisProperties ),
  leftAxis = graphinstance.getLeftAxis( 0, axisProperties );

graphinstance.newSerie( "current" )
  .autoAxis()
  .setData( series[ 0 ] )
  .setLineColor( 'black' );

graphinstance.redraw(); // Need to force an axis redraw first

xAxis2.linkToAxis( xAxis, function( val ) {
  return Math.pow( val + 2, 2 );
}, 1 );

graphinstance.getXAxis().setLabel( 'Voltage (V)' );
graphinstance.getYAxis().setLabel( 'Current (mA cm-2)' );

graphinstance.redraw();
graphinstance.drawSeries();