Cathode including sintered polycrystalline material, secondary battery including the cathode, and method of manufacturing the cathode

Abstract

A cathode includes a cathode collector layer, and a cathode active material layer on a surface of the cathode collector layer. The cathode active material layer includes a sintered polycrystalline material having a plurality of crystal grains of a lithium-based oxide, and each of the plurality of crystal grains includes a seed template, and a matrix crystal around the seed template, where the seed template is a single crystal and having a shape of a plate.

What is claimed is: 
     
         1 . A cathode comprising:
 a cathode collector layer; and   a cathode active material layer on a surface of the cathode collector layer,   wherein the cathode active material layer comprises a polycrystalline material having a plurality of crystal grains of a lithium-based oxide, and   wherein the plurality of crystal grains are substantially oriented such that an angle between a direction perpendicular to a surface of the cathode collector layer and a direction of a lithium plane defined by lithium elements arranged in layers in the plurality of crystal grains is within about ±45°.   
     
     
         2 . The cathode of  claim 1 , wherein at least one of the plurality of crystal grains are oriented such that the lithium plane is substantially perpendicular to a surface of the cathode collector layer. 
     
     
         3 . The cathode of  claim 1 , wherein
 a crystal direction of the plurality of crystal grains substantially perpendicular to a surface of the cathode collector layer comprises at least one of directions <h00>, <0k0>, <hk0>, <101>, <012>, <104>, <113>, <021>, and <024>,   wherein “h” and “k” are integers equal to or greater than 1.   
     
     
         4 . The cathode of  claim 1 , wherein
 the lithium-based oxide comprises Li x MO 2 ,   wherein “M” is at least one of cobalt (Co), nickel (Ni), manganese (Mn), and   “x” is in a range of 0.2<x<1.2.   
     
     
         5 . The cathode of  claim 1 , wherein the cathode active material layer directly contacts the cathode collector layer. 
     
     
         6 . The cathode of  claim 1 , wherein each of the plurality of crystal grains comprises:
 a seed template; and   a matrix crystal around the seed template,   wherein the seed template is a single crystal and having a shape of a plate.   
     
     
         7 . The cathode of  claim 6 , wherein a surface of the seed template having the shape of the plate, which faces a surface of the cathode collector layer, is substantially parallel to the surface of the cathode collector layer. 
     
     
         8 . The cathode of  claim 7 , wherein an angle between a surface of the seed template having the shape of the plate, which faces a surface of the cathode collector layer, and a surface of the cathode collector layer is in a range of about ±45°. 
     
     
         9 . The cathode of  claim 6 , wherein the seed template and the matrix crystal have different compositions from each other. 
     
     
         10 . A secondary battery comprising:
 an anode collector layer;   an anode active material layer on a surface of the anode collector layer;   a cathode collector layer; and   a cathode active material layer on a surface of the cathode collector layer,   wherein the cathode active material layer comprises a polycrystalline material having a plurality of crystal grains of a lithium-based oxide, and   wherein the plurality of crystal grains are substantially oriented such that an angle between a direction perpendicular to a surface of the cathode collector layer and a direction of a lithium plane defined by lithium elements arranged in layers in the plurality of crystal grains is within about ±45°.   
     
     
         11 . The secondary battery of  claim 10 , wherein at least one of the plurality of crystal grains are oriented such that the lithium plane is substantially perpendicular to a surface of the cathode collector layer. 
     
     
         12 . The secondary battery of  claim 10 , wherein
 a crystal direction of the plurality of crystal grains substantially perpendicular to a surface of the cathode collector layer comprises at least one of directions <h00>, <0k0>, <hk0>, <101>, <012>, <104>, <113>, <021>, and <024>,   wherein “h” and “k” are integers equal to or greater than 1.   
     
     
         13 . The secondary battery of  claim 10 , wherein
 the lithium-based oxide comprises Li x MO 2 ,   wherein “M” is at least one of cobalt (Co), nickel (Ni), manganese (Mn), and   “x” is in a range of 0.2<x<1.2.   
     
     
         14 . The secondary battery of  claim 10 , wherein the cathode active material layer directly contacts the cathode collector layer. 
     
     
         15 . The secondary battery of  claim 10 , wherein each of the plurality of crystal grains comprises:
 a seed template; and   a matrix crystal around the seed template,   wherein the seed template is a single crystal and having a shape of a plate.   
     
     
         16 . The secondary battery of  claim 15 , wherein a surface of the seed template having the shape of the plate, which faces a surface of the cathode collector layer, is substantially parallel to the surface of the cathode collector layer. 
     
     
         17 . The secondary battery of  claim 16 , wherein an angle between a surface of the seed template having the shape of the plate, which faces a surface of the cathode collector layer, and a surface of the cathode collector layer is in a range of about ±45°. 
     
     
         18 . The secondary battery of  claim 15 , wherein the seed template and the matrix crystal have different compositions from each other. 
     
     
         19 . The secondary battery of  claim 10  further comprising an electrolyte layer between the cathode active material layer and the anode active material layer. 
     
     
         20 . The secondary battery of  claim 1  further comprising a separation film between the cathode active material layer and the anode active material layer.