Nitride and carbide anode materials
Described is an anode material which is a transition metal nitride or carbide in form of nanoparticles, preferably a nitride or carbide with one nitrogen or carbon per metal, and especially a nitride or carbide having rock salt structure. A preferred anode material is vanadium nitride, in particular carbon coated vanadium nitride having a mean particle size of <500 nm. Embedded in an electrically conducting environment, such nanoparticulate material, in particular the vanadium nitride shows exceptional good charging-discharging cycle stability.
1. An anode material for a rechargeable lithium battery, the anode material being an open porous nanocomposite material comprising:
(a) homogeneously distributed nanoparticles of electrically active anode material, referred to hereinafter as EAAM; and
(b) nanoparticles of electrically conductive binder, hereinafter referred to as CB,
wherein the nanoparticles of EAAM are carbon coated and arranged for undergoing lithiation in the battery,
wherein the EAAM undergoes no substantial change of structure upon lithiation, wherein the nanoparticles of CB are mixed with the homogeneously distributed nanoparticles of EAAM so as to form an electrically conductive environment, in which the nanoparticles of EAAM are embedded, and wherein the EAAM is a transition metal interstitial nitride with one nitrogen per metal or a transition metal interstitial carbide with one carbon per metal, the nitride or carbide having a rock salt, a CsCl, a Zinc Blende, a Wurtzite or a Nickel Arsenide crystal structure type.
2. The anode material according to claim 1 , wherein lithiation of the EAAM is produced by the intercalation of Lithium atoms in the crystal structure of the nanoparticles of EAAM.
3. The anode material of claim 1 wherein the nanoparticles of EAAM have mean particle sizes <500 nm, in particular mean particle sizes in the range of 5 to 500 nm, preferably in the range of 5 to 400 nm, more preferred in the range of 20 to 300 nm.
4. The anode material of claim 1 , wherein the EAAM is selected from nitrides.
5. The anode material of claim 4 , wherein the nitrides are selected from the group consisting of TiN, ZrN, HfN, VN, NbN, TaN, CrN, MoN, WN and mixtures thereof, preferably TiN, ZrN, VN, NbN, CrN, MoN and mixtures thereof.
6. The anode material of claim 4 , wherein the nitride is vanadium nitride.
7. The anode material of claim 1 , wherein the EAAM is a carbide, in particular a carbide selected from the group consisting of TiC, ZrC, HfC, VC, NbC, TaC and mixtures thereof, more preferred TiC, ZrC, VC, NbC and mixtures thereof.
8. The anode material of claim 1 , wherein the electrically conducting environment comprises carbon black and/or graphite and the nanoparticles of CB, and wherein the CB is selected from the group consisting of polyisobutene, polytetrafluoroethylene, polythiophene, polyaniline, polyvinylchloride and PEDOT.
9. The anode material of claim 8 , wherein the CB is selected from the group consisting of polyvinylidenfluoride and PEDOT.
10. The anode material of claim 9 , wherein the electrically conducting environment comprises nanopartices of PEDOT.
11. An anode made from an anode material of claim 1 , wherein the anode material is glued to a conductor such as graphite or aluminium via an adhesive, preferably the CB.
12. A method for the production of an anode in a rechargeable lithium battery, the method comprising the steps of:
(a) providing metal nitrides and carbides as defined in claim 1 ; and
(b) producing the anode.