NOVELTY - Composition comprises at least 50 wt.% of a particulate electroactive material and at least 3-15 wt.% of carbon additives comprising elongate carbon nanostructures and carbon black, where the elongate carbon nanostructures comprise at least a first elongate carbon nanostructure material and a second elongate carbon nanostructure material; and the elongate carbon nanostructures : carbon black weight ratio is in the range of 3:1 to 20:1.    USE - The composition is useful for preparing metal-ion battery, and slurry for forming metal-ion battery (all claimed). Generally, it can be used for batteries and fuel cells.    ADVANTAGE - Anode composition for metal ion battery that is capable of maintaining a high capacity is provided. Active graphite may provide for a larger number of charge/discharge cycles without significant loss of capacity than active silicon, while silicon may provide for higher capacity than graphite. Accordingly, electrode composition having both silicon-containing active particles and graphite active material may provide a metal ion battery, for example lithium ion battery, with the advantages of both high capacity and a large number of charge/discharge cycles. Graphite present in the composition may also improve coating properties of slurry of the composition as compared to a composition in which graphite is absent.    DETAILED DESCRIPTION - Composition comprises at least 50 wt.% of a particulate electroactive material and at least 3-15 wt.% of carbon additives comprising elongate carbon nanostructures and carbon black, where the elongate carbon nanostructures comprise at least a first elongate carbon nanostructure material and a second elongate carbon nanostructure material; and the elongate carbon nanostructures : carbon black weight ratio is in the range of 3:1 to 20:1; or composition comprises a particulate electroactive material; a first elongate carbon nanostructure material; and a second elongate carbon nanostructure material, where the first elongate carbon nanostructure material has a mean average diameter of at least 100 nm; the second elongate carbon nanostructure material has a mean average diameter of less than 90 nm, and where the particulate electroactive material comprises particles having a particle core and pillars of the electroactive material extending from the particle core; composition comprises a particulate electroactive material; a first elongate carbon nanostructure material; and a second elongate carbon nanostructure material, where the first elongate carbon nanostructure material has a mean average diameter of at least 100 nm; and the second elongate carbon nanostructure material has a mean average diameter in the range of 40-90 nm; composition comprises a binder; a particulate electroactive material and carbon additives comprising a first elongate carbon nanostructure material; a second elongate carbon nanostructure material; graphite; and carbon black; composition comprises a binder; a particulate electroactive material; carbon nanostructure additives comprising a first elongate carbon nanostructure material, a second elongate carbon nanostructure material, and optionally carbon black where the carbon nanostructure additives form no more than 10 wt.% of the composition; or composition comprises a binder; a particulate electroactive material; and at least one elongate carbon nanostructure material where the elongate carbon nanostructure material has a functionalized surface. INDEPENDENT CLAIMS are included for:    (1) a metal-ion battery comprising an anode, a cathode and an electrolyte between the anode and the cathode where the anode comprises the composition above;    (2) a slurry comprising the composition above and at least one solvent; and    (3) a method of forming a metal-ion battery involving forming an anode by depositing the slurry onto a conductive material and evaporating at least one solvent.