Difluorophosphate additive compounds and methods thereof for use in energy storage devices
AssigneeTesla, Inc.
InventorsDavid S. Hall, Toren Hynes, Connor P. Aiken, Jeffery R. Dahn
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Abstract
The present disclosure relates to the synthesis and evaluation of difluorophosphate additives for use in energy storage devices. The difluorophosphate additive may be selected from the group consisting of lithium difluorophosphate (LFO), sodium difluorophosphate (NaFO), ammonium difluorophosphate (AFO), tetramethylammonium difluorophosphate (MAFO), potassium difluorophosphate (KFO), and combinations thereof. In some instances, the difluorophosphate additive is not lithium difluorophosphate (LFO).
Claims20
An energy storage device, comprising:
- an anode comprising an anode active material consisting of a carbon material;
- a cathode;
- a housing;
- and
- an electrolyte comprising a lithium salt, a solvent, and an additive consisting of sodium difluorophosphate (NaFO) and at least one additional difluorophosphate additive selected from the group consisting of:
- lithium difluorophosphate (LFO), ammonium difluorophosphate (AFO), tetramethylammonium difluorophosphate (MAFO), potassium difluorophosphate (KFO), and combinations thereof;
- wherein the anode, cathode and electrolyte are positioned within the housing;
- wherein the electrolyte comprises 0.1 wt. % to 5 wt. % of NaFO, and 0.1 wt. % to 5 wt. % of the additional difluorophosphate additive;
- and
- wherein the device has a charge transfer resistance (Rct) of less than about 60 Ohms/cm2 after formation at a voltage of 4.3V-4.4V.
A method of fabricating an energy storage device, comprising:
- positioning an anode, a cathode and an electrolyte within a housing, wherein the electrolyte comprises a lithium salt, a solvent, and an additive consisting of sodium difluorophosphate (NaFO) and at least one additional difluorophosphate additive selected from the group consisting of:
- lithium difluorophosphate (LFO), ammonium difluorophosphate (AFO), tetramethylammonium difluorophosphate (MAFO), potassium difluorophosphate (KFO), and combinations thereof;
- wherein the anode comprises an anode active material consisting of a carbon material;
- wherein the electrolyte comprises 0.1 wt. % to 5 wt. % of NaFO, and 0.1 wt. % to 5 wt. % of the additional difluorophosphate additive;
- sealing the housing to form an energy storage device;
- and
- forming a solid-electrolyte interphase (SEI) at the anode, wherein forming the SEI comprises charge cycling the energy storage device to a voltage of at least about 4.3V.
Dependencies are inferred from the claim text.