NOVELTY - Porous silicon based material comprises porous crystalline elemental silicon having an X-ray diffraction spectra, using a copper K alpha source, with a crystalline silicon peak at a value of 2 theta , as given in the specification, and an average pore sizes of 5-500 nm in diameter, where the porous silicon is substantially free of carbon embedded within the silicon structure.    USE - The porous silicon based material is useful in a lithium based battery electrode, which is useful in a lithium ion battery (all claimed) and automobile batteries such as electric vehicles, plug-in hybrid vehicles and hybrid vehicles.    ADVANTAGE - The porous silicon based material provides lithium ion battery with high degree of crystallinity and porosity, capacity, energy density, and electrical conductivity, good cycling properties, improved structural stability and good mechanical strength.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a lithium based battery electrode comprising a binder and the porous silicon based material, where the electrode has a discharge specific capacity of at least 1800 mAh/g at the 7th cycle at rate of C/3 discharged of 1.5-0.005V against lithium;    (2) a lithium ion battery (100) comprising the electrode, a positive electrode (104) comprising a lithium metal oxide compound of formula (Li1+bNi( alpha )Mn( beta )Co( gamma )A( delta )O2-2F2), and a separator (106) between the negative electrode (102) and the positive electrode, where the positive electrode has a discharge specific capacity of at least 200 mAh/g at rate of C/3; and    (3) forming porous crystalline elemental silicon, comprising reducing a blend of silicon dioxide and a reducing metal at a target temperature of 550-950 degrees C to form an intermediate comprising crystalline elemental silicon and metal oxide, where the blend is formed by milling the silicon dioxide and a powder of the reducing metal.    A = Mg, Sr, Ba, Cd, Zn, Al, Ga, B, Zr, Ti, Ca, Ce, Y, Nb, Cr, Fe, V, and/or Li;    b = 0.01-0.3;    alpha = 0-0.4;    beta = 0.2-0.65;    gamma = 0-0.46;    delta = 0-0.15; and    z = 0-0.2, provided that both alpha and gamma are not zero.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic perspective view of an electrode.    Lithium ion battery (100)    Negative electrode (102)    Positive electrode (104)    Separator (106)    Current collector. (108)