TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Claimed Preparation: The modified particles are prepared in two stages. Firstly, the modification of the form of the particles is by a physical method, which enables the reduction by at least 50% of the basal function (fb) and increase of the edge function (fe). The method is an attrition process, by jet mill, ball mill, hammer mill or atomizer mill, of the natural or synthetic graphite particles in the presence of a compound MFz, where M is an alkali or alkaline earth metal and z is 1 or 2.More preferably the compound is CaF2, BaF2 or LiF or a mixture. The compound(s) are solid, at ambient temperature and added at the commencement of the stage. Reduction of the surface impurities by chemical purification of the particles obtained in (1).Claimed Uses: The modified particles can be used in fuel cells, electrochemical generators and moisture or oxygen sensors.A negative electrode, for a rechargeable cell, is prepared from the graphite particles with a binder, preferably PVDF or PTFE. The stages are:(1) a solution of the binder in a solvent such as NMP or cyclopentanone to obtain a viscous solution;(2) spreading of the solution obtained above(a powder-binder composition) on a metallic collector;(3) drying of the electrode obtained by an IR lamp or heating element.In an alternative form of the invention, prismatic graphite particles are coated with a metallic and-or carbon deposit, their characteristics being as defined above, and the particles size is 1-50 microns and the sphericity 80% or more.The average thickness of the metallic and/or carbon coating is 50 nm-2 microns.The particles comprises a graphite nucleus making up at least 905 of the total weight, the remaining 10% consisting of a metal from Ag, Si, Al and Cu and/or carbon and/or carbonized polymer.The particles are prepared as above by coating and maintaining the basal function and edge function constant to obtain a sphericity of 80% +.Preferred Particles: In addition to the characteristics above, the graphite particles (of patatoid but preferably spherical shape) may have surface particle impurities of NaCl and/or NH4F of mass between 1-10%, preferably 1-4%.The TGA analysis gives an initial temperature wt. loss value at 560-660degreesC. Other impurities present may include elements from Fe, Mo, Sb, As, V, Cr, Cu, Ni, Pb, Co, Ca, Al, Ge, Si, Ba, Be, Cd, Ce, Co, Dy, Eu, La, Li and Pr, present as 1-10%, preferably 2-4%.The graphite is preferably substantially free from surface imputes.The particles may contain 5- 20% of SiO2, MgO, ceramics or a mixture of these.The graphite particles have an interplanar distance d002 of 3.3-3.4 Angstrom and/or a surface area of 0.5-50 g/m2 and have a stability to cycling greater than 500 cycles.Preferred Preparation: The graphite particles initially have a size range of 1-450 (more preferably 2-350) microns.The attrition treatment is carried out in the presence of an additive , preferably an oxide such as SiO2, TiO2 or ZrO2, and also in the presence of steel or ceramic balls or a mixture.The two stages are effected in a controlled atmosphere, N2 Ar, He or a mixture or air.The preferred attrition technique is jet milling. EXAMPLE - Modified patatoid graphite particles are prepared from natural graphite of initial size 375 microns, of 98% purity and surface area 1 m2/g in flake form. The powder was milled by an attrition process to transform the particles to a spherical form. The d002 parameter did not change after forming, and had a value of 3.36 Angstrom. Scanning electron microscope analysis showed the change of form before and after attrition whilst the size was maintained on the same scale. A fluorinated polyvinylidine binder, PVDF, was dissolved in n-methyl pyrrolidone. An acetone/toluene mixture(80/20) was added to the PVDF-NMP paste to form a spreading composition and the transformed spheroidized graphite dispersed in the composition in a ratio of 90 : 10. This was applied to a Cu collector and the electrode obtained dried by IR. This was mounted in a button battery of 2035 type which used a Cellgard 2300(TM) separator soaked in an electrolyte 1M LiPF6 + ethylene carbonate/dimethyl carbonate (50/50). Electrochemical tests were carried out at ambient temperature.    The results were comparable to those obtained with electrodes prepared from natural flake graphite and artificial graphite.