TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: In the composition, the porous particle fragments have an average thickness in the range of 50 nm to 2 mu m. The silicon containing porous particle fragments have a maximum diameter of less than 40 mu m. The silicon containing porous particle fragment has an aspect ratio (length (largest diameter) to width (smallest diameter) of particle) in the range of 2:1 to 5:1. The composition comprises 10 to 100 vol.% of porous particle fragments having a maximum diameter of less than 40 mu m. The fragment is a fractal and the fractal structure comprises a substantially irregular shape and/or surface morphology, these fractal structures being derived from: (a) the silicon material originally defining or bounding the pores or network of pores within the porous particle from which the fractal fragment structures are derived, without themselves comprising pores, channels or a network of pores or channels; or (b) the silicon material originally defining a random or ordered network of linear, branched or layered elongate elements, where one or more discrete or interconnected void spaces or channels are defined between the elongate elements of the network. Fractal structure comprises at least one peak or ridge disposed over the surface. Fractal structure has a spiky appearance. The fractal structure has a ridged appearance. Elongate elements comprising a random or ordered network have a thickness of from 0.05 to 2 mu m, preferably 0.1 to 1 mu m. The pore containing porous particle fragments comprise a three dimensional network of pores, cavities and channels, the pores, channels and cavities being separated and defined by silicon containing walls within the particle structure. The silicon containing walls have a thickness in the range of 0.05 to 2 mu m, preferably 0.1 to 1 mu m. Each pore has a width in the range of 100 nm to 10 mu m, preferably 150 nm to 5 mu m. The ratio of pore width to wall thickness is greater than 2.5:1 and is preferably in the range 3:1 to 25:1. Ratio of the total volume of the pores in the fragment to the total volume of the fragment is in the range of 0.2 to 0.9, preferably 0.2 to 0.8, more preferably 0.25 to 0.75 and especially 0.3 to 0.7. The particle fragments have a Brunauer-Emmett-Teller (BET) surface area greater than 4 m2/g preferably greater than 5 m2/g. The composition is an electroactive material. It further comprises one or more components selected from a binder, a conductive material and optionally a non-silicon containing electroactive material, such as graphite. It comprises 50 to 90% of electroactive material by weight. Electroactive material comprises from 10 to 100% silicon containing porous particle fragments by weight. The composition comprises 5 to 40 wt.% of a silicon-containing electroactive material including a silicon-containing porous particle fragment and 60 to 95 wt.% of an electroactive carbon material. The porous particle fragments comprise 10 to 100% of the silicon-containing electroactive material. The composition comprises 70 wt.% silicon-containing porous particles and 30 wt.% of electroactive carbon material. The binder is selected from a polyacrylic acid, a modified polyacrylic acid, a polyethylene maleic anhydride, an alkali metal salt of a polyacrylic acid, an alkali salt of a modified polyacrylic acid, an alkali metal salt of a polyethylene maleic anhydride and its mixtures. The composition further comprises one or more silicon further containing components selected from native silicon containing particles having a minimal or negligible porosity; silicon containing wires, nano-wires, fibers, rods, tubes, sheets, elongate bundles, substrate particles, scaffolds, ribbons and silicon containing pillared particles. The further silicon containing components are electro-active. One or more of the silicon containing porous particle fragments and one or more silicon containing components include a coating, where the coating is a carbon coating or a coating comprising a lithium salt. The composition also comprises one or more components selected from a viscosity adjuster, a cross-linking accelerator, a coupling agent and an adhesive accelerator. Electrode material is an anode material. The composition is an electrode material. It is in the form of a mat. Preferred Method: In making composition, the silicon containing fragments are obtained by partially crushing silicon containing whole porous particles having a diameter greater than 40 mu m, preferably greater than 20 mu m. The method further comprises: (a) forming a molten silicon aluminum alloy composition; (b) cooling the molten composition to give alloy particles; (c) etching the alloy particles to give silicon-containing porous particles; and (d) partially crushing the silicon-containing porous particles from (c) to give silicon-containing porous particle fragments. The molten alloy composition comprises from 11 to 35 wt.% silicon. The molten composition is cooled at a rate of between 102 and 105 K/second. It is cooled at a rate of 102 to 103 K/second using a gas atomization technique or a melt spinning technique. The cooled alloy particles have a diameter of from 40 to 1500 mu m. In manufacturing electrode, the solvent is selected from N-methylpyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, propylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, gamma butyrolactone, 1,2-dimethoxy ethane, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, acetonitrile, nitromethane, methylformate, methyl acetate, phosphoric acid trimester, trimethoxy methane, sulfolane, methyl sulfolane and 1,3-dimethyl-2-imidazolidione. Preferred Electrode: The electrode is an anode. The current collector is selected from copper foil, aluminum, graphite and nickel. The composition is in the form of a mat or felt connected, adhered or applied to a current collector. It is in the form of a free standing felt or mat to which a current collector is connected. It is in the form of a felt or mat having a mass per surface area of between 1 mg/cm2 and 6 mg/cm2 to give a composite electrode having a thickness of from 10 to100 mu m. Preferred Battery: In the battery, the cathode is selected from LiCoO2, LiCo0.99A10.01O2, LiNiO2, LiMnO2, LiCo0.5Ni0.5O2, LiCo0.7Ni0.3O2, LiCo0.8N10.2O2, LiCo0.82Ni0.18O2, LiCo0.8Ni0.15Al0.05O2, LiNi0.4Co0.3Mn0.3O2 and LiNi0.33Co0.33Mn0.34O2. The electrolyte is selected from a non-aqueous electrolytic solution, a solid electrolyte and an inorganic solid electrolyte. It further comprises one or more lithium salts selected from lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), LiClO4, LiBF4, LiB10C20, LIPF6, L1CF3SO3, LIAsF6, L1SbF6, LIBoB, L1AICl4, CH3SO3Li and CF3SO3Li.