Coated positive electrode materials for lithium ion batteries

Abstract

High specific capacity lithium rich lithium metal oxide materials are coated with inorganic compositions, such as metal fluorides, to improve the performance of the materials as a positive electrode active material. The resulting coated material can exhibit an increased specific capacity, and the material can also exhibit improved cycling. The materials can be formed while maintaining a desired relatively high average voltage such that the materials are suitable for the formation of commercial batteries. Suitable processes are described for the synthesis of the desired coated compositions that can be adapted for commercial production.

What is claimed is: 
     
         1 . A lithium ion battery comprising a positive electrode, a negative electrode comprising a lithium incorporation composition, a separator between the positive electrode and the negative electrode and an electrolyte comprising lithium ions, wherein the positive electrode comprises an active material, distinct electrically conductive powders and a polymer binder, wherein the positive electrode active material comprises an active lithium metal oxide composition coated with an inorganic coating composition, and the positive electrode active material having a discharge specific capacity of at least about 190 mAh/g with a discharge rate of 2 C from 4.6 volts to 2.0 volts at room temperature for the fifteenth charge/discharge cycle. 
     
     
         2 . The lithium ion battery of  claim 1  wherein the negative electrode comprises graphitic carbon. 
     
     
         3 . The lithium ion battery of  claim 1  wherein the inert inorganic coating composition comprises a metal/metalloid fluoride. 
     
     
         4 . The lithium ion battery of  claim 1  wherein the coating composition has an average thickness from about 0.5 nm to about 12 nm. 
     
     
         5 . The lithium ion battery of  claim 1  wherein the inert inorganic coating composition comprises a metal/metalloid oxide. 
     
     
         6 . The lithium ion battery of  claim 1  wherein the active lithium metal oxide composition is approximately represented by the formula Li 1+x M 1+x O 2 , where M is a metal element or a combination thereof and 0.01≦x≦0.3. 
     
     
         7 . The lithium ion battery of  claim 1  wherein the active lithium metal oxide composition can be approximately represented by a formula of bLiM′O 2 .(1−b) Li 2 M″O 3 , where M′ represents one or more metal ions having an average valance of +3 and M″ represents one or more metal ions having an average valance of +4 and 0<b<1. 
     
     
         8 . The lithium ion battery of  claim 1  wherein the active lithium metal oxide composition can be approximately represented by a formula Li 1+x Ni α Mn β Co γ A δ O 2 , where x ranges from about 0.05 to about 0.25, α ranges from about 0.1 to about 0.4, β ranges from about 0.4 to about 0.65, γ ranges from 0 to about 0.3, and δ ranges from 0 to about 0.1, and where A is Mg, Zn, Al, Ga, B, Zr, Ti, Ca, Ce, Y, Nb, Cr, Fe, V, Li or combinations thereof. 
     
     
         9 . The lithium ion battery of  claim 1  wherein the irreversible capacity loss of the battery is reduced by at least about 10% relative to the irreversible capacity loss of an equivalent battery formed with the uncoated active lithium metal oxide. 
     
     
         10 . The lithium ion battery of  claim 1  wherein the active lithium metal oxide composition has a tap density of at least about 1.3 g/mL. 
     
     
         11 . A lithium ion battery comprising a positive electrode, a negative electrode comprising a lithium incorporation composition and a separator between the positive electrode and the negative electrode, wherein the positive electrode comprises an active material having an active lithium metal oxide composition coated with an inorganic coating composition, distinct electrically conductive powers and a polymer binder, the positive electrode active material having a discharge specific capacity of at least about 245 mAh/g, an average voltage of at least about 3.55 volts and a capacity at 40 cycles that is at least about 90% of the capacity at 10 cycles with a discharge rate of C/3 from 4.6 volts to 2.0 volts at room temperature. 
     
     
         12 . The lithium ion battery of  claim 11  wherein the positive electrode active material has a specific capacity of at least about 250 mAh/g with a discharge rate of C/3 from 4.6 volts to 2.0 volts at room temperature. 
     
     
         13 . The lithium ion battery of  claim 11  wherein a capacity at 40 cycles that is at least about 95% of the capacity at 10 cycles with a discharge rate of C/3 from 4.6 volts to 2.0 volts at room temperature. 
     
     
         14 . The lithium ion battery of  claim 11  wherein the inorganic coating composition comprises a metal/metalloid fluoride. 
     
     
         15 . The lithium ion battery of  claim 11  wherein the inorganic coating composition comprises AlF 3 , MgF 2 , CaF 2 , SrF 2  or BaF 2 . 
     
     
         16 . The lithium ion battery of  claim 11  wherein the inorganic coating has an average thickness from about 1 nm to about 8 nm. 
     
     
         17 . The lithium ion battery of  claim 11  wherein the active lithium metal oxide composition can be approximately represented by the formula Li 1+x M 1−x O 2 , where M is one or more metal elements and 0.01≦x≦0.3. 
     
     
         18 . The lithium ion battery of  claim 11  wherein the active lithium metal oxide composition can be approximately represented by a formula of bLiM′O 2 .(1−b) Li 2 M″O 3 , where M′ represents one or more metal ions having an average valance of +3 and M″ represents one or more metal ions having an average valance of +4 and 0<b<1. 
     
     
         19 . The lithium ion battery of  claim 11  wherein the active lithium metal oxide composition can be approximately represented by a formula Li 1+x Ni α Mn β Co γ M″ δ O 2 , where x ranges from about 0.05 to about 0.25, α ranges from about 0.1 to about 0.4, β ranges from about 0.4 to about 0.65, γ ranges from 0 to about 0.3, and δ ranges from 0 to about 0.1, and where M″ is Mg, Zn, Al, Ga, B, Zr, Ti, Ca, Ce, Y, Nb, Cr, Fe, V, Li or combinations thereof. 
     
     
         20 . The lithium ion battery of  claim 11  wherein the negative electrode comprises graphitic carbon.