Protective layers in lithium-ion electrochemical cells and associated electrodes and methods

Abstract

Protective layers in lithium-ion electrochemical cells, and associated electrodes and methods, are generally described. The protective layers may comprise lithium-ion-conductive inorganic ceramic materials, such as lithium oxide, lithium nitride, and/or lithium oxysulfide. The resulting lithium-ion electrochemical cells may exhibit enhanced performance, including reduced capacity fade rates and reduced self-discharge rates.

What is claimed is: 
     
         1 . (canceled) 
     
     
         2 . An electrochemical cell, comprising:
 a first electrode, wherein the first electrode is a lithium intercalation electrode, and wherein the first electrode comprises:   a layer comprising a first electroactive material, wherein the first electroactive material is a lithium intercalation compound; and   an inorganic lithium-ion-conductive layer disposed on a surface of the layer comprising the first electroactive material, wherein the inorganic lithium-ion-conductive layer comprises particles that are substantially aligned;   a liquid electrolyte, wherein the liquid electrolyte is an organic electrolyte; and   
       a second electrode. 
     
     
         3 . A method of fabricating an electrochemical cell, comprising:
 depositing an inorganic lithium-ion-conductive layer on a layer comprising a first electroactive material to form a first electrode, wherein the first electroactive material is a lithium intercalation compound, wherein the inorganic lithium-ion-conductive layer comprises particles that are substantially aligned; and   assembling the first electrode with a liquid electrolyte and a second electrode.   
     
     
         4 . The electrochemical cell of  claim 2 , wherein at least a portion of the first electroactive material is in direct contact with the liquid electrolyte. 
     
     
         5 . The method of  claim 3 , wherein at least a portion of the first electroactive material is in direct contact with the liquid electrolyte. 
     
     
         6 . The electrochemical cell of  claim 2 , wherein:
 the inorganic lithium-ion-conductive layer comprises lithium; and   at least a portion of the first electrode is in contact with the electrolyte.   
     
     
         7 . A method, comprising:
 cycling the electrochemical cell of  claim 3 , wherein the inorganic lithium-ion-conductive layer comprises lithium; and   substantially inhibiting a species decomposed from the first electrode and/or a species decomposed from the electrolyte from residing at the second electrode.   
     
     
         8 . The electrochemical cell of  claim 2 , wherein the inorganic lithium-ion-conductive layer has a thickness of at least 0.1 microns and at most 10 microns. 
     
     
         9 . The electrochemical cell of  claim 2 , wherein the layer comprising the first electroactive material comprises a plurality of particles of the first electroactive material. 
     
     
         10 . The electrochemical cell of  claim 9 , wherein at least a portion of the plurality of particles of the first electroactive material have a coating. 
     
     
         11 . The electrochemical cell of  claim 2 , wherein the inorganic lithium-ion-conductive layer comprises a ceramic material. 
     
     
         12 . The electrochemical cell of  claim 11 , wherein the ceramic material comprises lithium oxide, lithium nitride, lithium oxysulfide, Li 10 GeP 2 S 12 , and/or Li 7 La 3 Zr 2 O 12 . 
     
     
         13 . The electrochemical cell of  claim 2 , wherein the inorganic lithium-ion-conductive layer has a surface roughness Rz of between 10 nm and 20 μm. 
     
     
         14 . The electrochemical cell of  claim 9 , wherein the plurality of particles of the layer comprising the first electroactive material has a mean maximum cross-sectional dimension of between 1 nm and 15 μm. 
     
     
         15 . The electrochemical cell of  claim 2 , wherein the layer comprising the first electroactive material has a porosity at least 10% by volume and less than 70% by volume. 
     
     
         16 . The electrochemical cell of  claim 2 , wherein the first electrode is a cathode. 
     
     
         17 . The electrochemical cell of  claim 2 , wherein the first electroactive material is a layered oxide, a transition metal polyanion oxide, and/or a spinel. 
     
     
         18 . The electrochemical cell of  claim 2 , wherein the first electroactive material is lithium titanate, lithium cobalt oxide, lithium iron phosphate, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt aluminum oxide, and/or lithium nickel cobalt manganese oxide. 
     
     
         19 . The electrochemical cell of  claim 2 , wherein a porosity of the inorganic lithium-ion-conductive layer is greater than or equal to 10% by volume and less than 30% by volume. 
     
     
         20 . The electrochemical cell of  claim 2 , wherein the inorganic lithium-ion-conductive layer is a unitary material. 
     
     
         21 . The electrochemical cell of  claim 2 , wherein a porosity of the inorganic lithium-ion-conductive layer is less than 5% by volume.