Method according to claim 1, characterized in that the graphite-based material is chosen from pencil leads, natural graphite a nd synthetic graphite.

Method according to cla i ms 1 to 3, characterized in that it also comprises a step (d) in which any organic or inorganic materials present in said dispersion are separated, preferably by sedimentation or centrifugation, or by chemical dissolution..3 5- 5. Method according to any one of claims 1 to 4, characterized in that it also comprises a step (e) in which said dispersion is red u ced of excessively thick graphite particles and/or graphene sheets that may be present in said dispersion, preferably by sedimentation or by centrifugation.

Method according to any one of claims 1 to 7, characterized in that the thickness of said graphene particles or sheets is between 1 and 50n m and/or the number of parallel graphene sheets is between I and 5 0, preferably between 1 and 30 and even more preferably between 1 and 15. 9, Method according to any one o f claims I to 8, characterized in that the speed o f friction between said material M (5) and said surface S (2) is between 0. 001m.s' and 0.im.s'.

Method according to any one of cla i ms 1 to 9, characterized in that said substrate is selected from the polymers, preferably flexible and/or transparent polymers, glasses, ceramics a n d silicon, 11. Method according to one of claims 1 to 10, in which said surface S (2) of said substrate and said massive material M (5) are in relative movement according to at least two axes, so as to cause a lateral offset between two adjacent segments of traces of said material M (5) on said surface S (2).

Method according to claim 11, in which said substrate is a disk capable of rotating about its axis, and in which the trace of friction of said massive material M (5) on said surface (2) is continuously or periodically offset by lateral displacement means (9) so as to obtain a continuous trace, preferably in the form of a spiral, 13. M ethod according to one of claims 1 to 12, in which steps (b) and (c) are performed simultaneously, and in which at least some of said dispersion is collected periodically or continuously, 14. Method according to one of claims 1 to 13, characterized in that said dispersion is subjected to a s e cond ultrasound tr e atm e nt, preferably with an ultrasound power and/or a duration greater than those in step (c).

Method according to one of claims 1 to 13, characterized in that said dispersion is then subjected to a microwave heating treatment.

Method for preparing graphene particles or sheets, in which a dispersion of graphen e particles or sheets is prepared according to any one of claims 1 to 15, followed by one or more 3i steps in which the graphene particles or sheets are collected from said suspension.

D evice for imple m enting the method according to one of claims 1 to 13, including:-means (3) capable of holding said bar or bloc k (5) of massive material M.-a substrate equipped with a surface S (2) capable of being in contact with said bar or block (5) of massive material M,-means (1) for displacement enabling a relative displacement between said massive material M and said substrate to be generated,-means for regulation and/or control of the pressure force (4) enabling the pressure force between said m assive m aterial M and said surface S of said substrate to be kept constant and/or measured d u ring said relative displacement,-a liquid container (19) enabling the surface S to be at least partially immersed in a liquid phase (6),-a n ultrasound generator (7) enabling said liquid (6) to be subjected to ultrasound,-optionally, drainage means (22) f o r the continuous or periodic drainage of said liquid container (19), in order to collect said liquid phase (6). Claims What is claimed is:

The device of claim 34, further comprising[[:]] means for one of a continuous and a periodic drainage of liquid from said liquid.

Method according to claim 1, characterized in that the graphite-based material is chosen from pencil leads, natural graphite a nd synthetic graphite.

Method according to cla i ms 1 to 3, characterized in that it also comprises a step (d) in which any organic or inorganic materials present in said dispersion are separated, preferably by sedimentation or centrifugation, or by chemical dissolution..3 5- 5. Method according to any one of claims 1 to 4, characterized in that it also comprises a step (e) in which said dispersion is red u ced of excessively thick graphite particles and/or graphene sheets that may be present in said dispersion, preferably by sedimentation or by centrifugation.

Method according to any one of claims 1 to 7, characterized in that the thickness of said graphene particles or sheets is between 1 and 50n m and/or the number of parallel graphene sheets is between I and 5 0, preferably between 1 and 30 and even more preferably between 1 and 15. 9, Method according to any one o f claims I to 8, characterized in that the speed o f friction between said material M (5) and said surface S (2) is between 0. 001m.s' and 0.im.s'.

Method according to any one of cla i ms 1 to 9, characterized in that said substrate is selected from the polymers, preferably flexible and/or transparent polymers, glasses, ceramics a n d silicon, 11. Method according to one of claims 1 to 10, in which said surface S (2) of said substrate and said massive material M (5) are in relative movement according to at least two axes, so as to cause a lateral offset between two adjacent segments of traces of said material M (5) on said surface S (2).

Method according to claim 11, in which said substrate is a disk capable of rotating about its axis, and in which the trace of friction of said massive material M (5) on said surface (2) is continuously or periodically offset by lateral displacement means (9) so as to obtain a continuous trace, preferably in the form of a spiral, 13. M ethod according to one of claims 1 to 12, in which steps (b) and (c) are performed simultaneously, and in which at least some of said dispersion is collected periodically or continuously, 14. Method according to one of claims 1 to 13, characterized in that said dispersion is subjected to a s e cond ultrasound tr e atm e nt, preferably with an ultrasound power and/or a duration greater than those in step (c).

Method according to one of claims 1 to 13, characterized in that said dispersion is then subjected to a microwave heating treatment.

Method for preparing graphene particles or sheets, in which a dispersion of graphen e particles or sheets is prepared according to any one of claims 1 to 15, followed by one or more 3i steps in which the graphene particles or sheets are collected from said suspension.

D evice for imple m enting the method according to one of claims 1 to 13, including:-means (3) capable of holding said bar or bloc k (5) of massive material M.-a substrate equipped with a surface S (2) capable of being in contact with said bar or block (5) of massive material M,-means (1) for displacement enabling a relative displacement between said massive material M and said substrate to be generated,-means for regulation and/or control of the pressure force (4) enabling the pressure force between said m assive m aterial M and said surface S of said substrate to be kept constant and/or measured d u ring said relative displacement,-a liquid container (19) enabling the surface S to be at least partially immersed in a liquid phase (6),-a n ultrasound generator (7) enabling said liquid (6) to be subjected to ultrasound,-optionally, drainage means (22) f o r the continuous or periodic drainage of said liquid container (19), in order to collect said liquid phase (6). Claims What is claimed is:

The device of claim 34, further comprising[[:]] means for one of a continuous and a periodic drainage of liquid from said liquid.

Method according to claim 1, characterized in that the graphite-based material is chosen from pencil leads, natural graphite a nd synthetic graphite.

Method according to cla i ms 1 to 3, characterized in that it also comprises a step (d) in which any organic or inorganic materials present in said dispersion are separated, preferably by sedimentation or centrifugation, or by chemical dissolution..3 5- 5. Method according to any one of claims 1 to 4, characterized in that it also comprises a step (e) in which said dispersion is red u ced of excessively thick graphite particles and/or graphene sheets that may be present in said dispersion, preferably by sedimentation or by centrifugation.

Method according to any one of claims 1 to 7, characterized in that the thickness of said graphene particles or sheets is between 1 and 50n m and/or the number of parallel graphene sheets is between I and 5 0, preferably between 1 and 30 and even more preferably between 1 and 15. 9, Method according to any one o f claims I to 8, characterized in that the speed o f friction between said material M (5) and said surface S (2) is between 0. 001m.s' and 0.im.s'.

Method according to any one of cla i ms 1 to 9, characterized in that said substrate is selected from the polymers, preferably flexible and/or transparent polymers, glasses, ceramics a n d silicon, 11. Method according to one of claims 1 to 10, in which said surface S (2) of said substrate and said massive material M (5) are in relative movement according to at least two axes, so as to cause a lateral offset between two adjacent segments of traces of said material M (5) on said surface S (2).

Method according to claim 11, in which said substrate is a disk capable of rotating about its axis, and in which the trace of friction of said massive material M (5) on said surface (2) is continuously or periodically offset by lateral displacement means (9) so as to obtain a continuous trace, preferably in the form of a spiral, 13. M ethod according to one of claims 1 to 12, in which steps (b) and (c) are performed simultaneously, and in which at least some of said dispersion is collected periodically or continuously, 14. Method according to one of claims 1 to 13, characterized in that said dispersion is subjected to a s e cond ultrasound tr e atm e nt, preferably with an ultrasound power and/or a duration greater than those in step (c).

Method according to one of claims 1 to 13, characterized in that said dispersion is then subjected to a microwave heating treatment.

Method for preparing graphene particles or sheets, in which a dispersion of graphen e particles or sheets is prepared according to any one of claims 1 to 15, followed by one or more 3i steps in which the graphene particles or sheets are collected from said suspension.

D evice for imple m enting the method according to one of claims 1 to 13, including:-means (3) capable of holding said bar or bloc k (5) of massive material M.-a substrate equipped with a surface S (2) capable of being in contact with said bar or block (5) of massive material M,-means (1) for displacement enabling a relative displacement between said massive material M and said substrate to be generated,-means for regulation and/or control of the pressure force (4) enabling the pressure force between said m assive m aterial M and said surface S of said substrate to be kept constant and/or measured d u ring said relative displacement,-a liquid container (19) enabling the surface S to be at least partially immersed in a liquid phase (6),-a n ultrasound generator (7) enabling said liquid (6) to be subjected to ultrasound,-optionally, drainage means (22) f o r the continuous or periodic drainage of said liquid container (19), in order to collect said liquid phase (6). Claims What is claimed is:

The device of claim 34, further comprising[[:]] means for one of a continuous and a periodic drainage of liquid from said liquid.

Method according to claim 1, characterized in that the graphite-based material is chosen from pencil leads, natural graphite a nd synthetic graphite.

Method according to cla i ms 1 to 3, characterized in that it also comprises a step (d) in which any organic or inorganic materials present in said dispersion are separated, preferably by sedimentation or centrifugation, or by chemical dissolution..3 5- 5. Method according to any one of claims 1 to 4, characterized in that it also comprises a step (e) in which said dispersion is red u ced of excessively thick graphite particles and/or graphene sheets that may be present in said dispersion, preferably by sedimentation or by centrifugation.

Method according to any one of claims 1 to 7, characterized in that the thickness of said graphene particles or sheets is between 1 and 50n m and/or the number of parallel graphene sheets is between I and 5 0, preferably between 1 and 30 and even more preferably between 1 and 15. 9, Method according to any one o f claims I to 8, characterized in that the speed o f friction between said material M (5) and said surface S (2) is between 0. 001m.s' and 0.im.s'.

Method according to any one of cla i ms 1 to 9, characterized in that said substrate is selected from the polymers, preferably flexible and/or transparent polymers, glasses, ceramics a n d silicon, 11. Method according to one of claims 1 to 10, in which said surface S (2) of said substrate and said massive material M (5) are in relative movement according to at least two axes, so as to cause a lateral offset between two adjacent segments of traces of said material M (5) on said surface S (2).

Method according to claim 11, in which said substrate is a disk capable of rotating about its axis, and in which the trace of friction of said massive material M (5) on said surface (2) is continuously or periodically offset by lateral displacement means (9) so as to obtain a continuous trace, preferably in the form of a spiral, 13. M ethod according to one of claims 1 to 12, in which steps (b) and (c) are performed simultaneously, and in which at least some of said dispersion is collected periodically or continuously, 14. Method according to one of claims 1 to 13, characterized in that said dispersion is subjected to a s e cond ultrasound tr e atm e nt, preferably with an ultrasound power and/or a duration greater than those in step (c).

Method according to one of claims 1 to 13, characterized in that said dispersion is then subjected to a microwave heating treatment.

Method for preparing graphene particles or sheets, in which a dispersion of graphen e particles or sheets is prepared according to any one of claims 1 to 15, followed by one or more 3i steps in which the graphene particles or sheets are collected from said suspension.

D evice for imple m enting the method according to one of claims 1 to 13, including:-means (3) capable of holding said bar or bloc k (5) of massive material M.-a substrate equipped with a surface S (2) capable of being in contact with said bar or block (5) of massive material M,-means (1) for displacement enabling a relative displacement between said massive material M and said substrate to be generated,-means for regulation and/or control of the pressure force (4) enabling the pressure force between said m assive m aterial M and said surface S of said substrate to be kept constant and/or measured d u ring said relative displacement,-a liquid container (19) enabling the surface S to be at least partially immersed in a liquid phase (6),-a n ultrasound generator (7) enabling said liquid (6) to be subjected to ultrasound,-optionally, drainage means (22) f o r the continuous or periodic drainage of said liquid container (19), in order to collect said liquid phase (6). Claims What is claimed is:

The device of claim 34, further comprising[[:]] means for one of a continuous and a periodic drainage of liquid from said liquid.