NOVELTY - Lithium ion electrochemical cell (I) comprises: an electrolyte comprising a vinylene carbonate additive (II) or an ethylene carbonate additive (III); and an anode composition containing a metal complex.    USE - (I) is useful in battery pack (claimed), portable computers, personal digital assistants, mobile telephones, motorized devices (e.g. personal or household appliances and vehicles), instruments, illumination devices (e.g. flashlights) and heating devices.    ADVANTAGE - (I) has increased life cycle and high energy density.    DETAILED DESCRIPTION - Lithium ion electrochemical cell (I) comprises: an electrolyte comprising a vinylene carbonate additive of formula (II) or an ethylene carbonate additive of formula (III); and an anode composition comprising a composition containing a metal complex of formula (SixSnqM1yCz) (where the silicon (Si), tin (Sn), M1 and carbon (C) elements are arranged in the form of a multi-phase microstructure containing an amorphous phase having Si, a nanocrystalline phase having a metal silicide, an amorphous phase having Sn when q is greater than 0, and a phase having a silicon carbide when z is greater than 0, a metal complex of formula (SiaAlbM2cSndE1eInp), where the alloy composition is a mixture of an amorphous phase having Si and a nanocrystalline phase having E1 and Sn when p is 0 or E1, Sn, and indium (In) when p is greater than 0, a metal complex of formula (SnfE2gE3hAiM3j) or a metal complex of formula (SikCumAgn)).    R1 = H or 1-4C (alkyl or alkenyl);    X = H, F or Cl;    Q = Cl or 1-4C (alkyl or alkenyl);    q, x, y, z = mole percentages and each mole percent is based upon the number of moles of all elements except lithium (Li) in the composition, (q+x) is greater than 2y+z, q and z greater than or equal to 0;    a, b, c, d, e, p = mole percentages and each mole percent is based upon the number of moles of all elements except Li in the composition, where a is 35-70, b is 1-45, c is 5-25, d is 1-15, e is 2-15 and p is 0-15;    f, g, h, i, j = mole percentages and each mole percent is based upon the number of moles of all elements except Li in the composition, where f is 1-50, g is 20-95, h is greater than or equal to 3, i is 0 or 3-50 and j is 0-1;    M1 = transition metal and/or Y;    M2 = transition metal and/or transition metals;    E1 = Y, lanthanide and/or actinide;    E2 = Si and/or Al;    E3 = Y, lanthanide and/or actinide;    A = alkaline earth element;    M3 = Fe, Mg, Si, Mo, Zn, Ca, Cu, Cr, Pb, Ti, Mn, C, S and/or P;    k, m, n = mole percentages and each mole percent is based upon the number of moles of all elements except Li in the composition, where the k is greater than or equal to 10, m is greater than or equal to 3 and n is 1-50.