Nanoscale Ion Storage Materials

Abstract

Nanoscale ion storage materials are provided that exhibit unique properties measurably distinct from their larger scale counterparts. For example, the nanoscale materials can exhibit increased electronic conductivity, improved electromechanical stability, increased rate of intercalation, and/or an extended range of solid solution. Useful nanoscale materials include alkaline transition metal phosphates, such as LiMPO 4 , where M is one or more transition metals. The nanoscale ion storage materials are useful for producing devices such as high energy and high power storage batteries, battery-capacitor hybrid devices, and high rate electrochromic devices.

1 . A lithium transition metal phosphate powder having a specific surface area of at least 15 m 2 /g and having a solid-solution lithium nonstoichiometry at room temperature (23° C.) that is at least 2 mole % more than the solid-solution lithium nonstoichiometry of a lithium transition metal phosphate of the same ideal composition prepared in a bulk form or as a powder of specific surface area less than about 10 m 2 /g, wherein the lithium transition metal phosphate has a composition Li 1-x MPO 4 , where M is one first-row transition metal, and 0<x<0.3 wherein the solid-solution comprises Li 1-x MPO 4  and Li y FePO 4  and 0.01<y<0.2. 
     
     
         2 . The lithium transition metal phosphate powder of  claim 1 , wherein the powder has a specific surface area of at least 20 m 2 /g. 
     
     
         3 . The lithium transition metal phosphate powder of  claim 1 , wherein the powder has a specific surface area of at least 25 m 2 /g. 
     
     
         4 . The lithium transition metal phosphate powder of  claim 1 , wherein the powder has a specific surface area of at least 30 m 2 /g. 
     
     
         5 . The lithium transition metal phosphate powder of  claim 1 , wherein the lithium transition metal phosphate has an olivine structure. 
     
     
         6 . (canceled) 
     
     
         7 . The lithium transition metal phosphate powder of  claim 1 , wherein M is iron. 
     
     
         8 . A partially lithiated iron phosphate composition of an olivine structure having at room temperature a single crystalline phase of the olivine structure, a solid solution composition Li y FePO 4  and Li 1-x FePO 4 , wherein 0<x<0.3 and 0.01<y≦0.2, and a specific surface area of at least 15 m 2 /g. 
     
     
         9 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.02. 
     
     
         10 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.03. 
     
     
         11 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.04. 
     
     
         12 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.05. 
     
     
         13 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.06. 
     
     
         14 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.07. 
     
     
         15 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.08. 
     
     
         16 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.09. 
     
     
         17 . The partially lithiated iron phosphate composition of  claim 8 , wherein y is greater than 0.10. 
     
     
         18 . (canceled) 
     
     
         19 . The partially lithiated iron phosphate composition of  claim 8 , wherein the lithium iron phosphate has a specific surface area greater than 20 m 2 /g. 
     
     
         20 . The partially lithiated iron phosphate composition of  claim 8 , wherein the lithium iron phosphate has a specific surface area greater than 25 m 2 /g. 
     
     
         21 . The partially lithiated iron phosphate composition of  claim 8 , wherein the lithium iron phosphate has a specific surface area greater than 30 m 2 /g. 
     
     
         22 . A lithium transition metal phosphate compound characterized in that, when used as a lithium storage electrode in a standard electrochemical cell wherein the counterelectrode is lithium metal, the compound exhibits a continuously decreasing charging current upon charging in a potentiostatic intermittent titration (PITT) procedure at a constant overpotential of 50 mV above the open-circuit voltage of the cell, said open-circuit voltage being measured after charging to a 50% state of charge and holding for at least 12 hours. 
     
     
         23 . The lithium transition metal phosphate compound of  claim 22 , wherein said open-circuit voltage is measured after charging to a 50% state of charge and holding for at least 12 hours at 25° C. 
     
     
         24 . The lithium transition metal phosphate compound of  claim 22 , wherein said open-circuit voltage is measured after charging to a 50% state of charge and holding for at least 12 hours over a temperature range of about −20° C. to about 55° C. 
     
     
         25 . The lithium transition metal phosphate compound of  claim 22 , wherein the compound is lithium transition metal phosphate Li 1-x MPO 4 , wherein M is one or more first-row transition metals and x has a value between zero and 1. 
     
     
         26 . The lithium transition metal phosphate compound of  claim 22 , wherein the lithium transition metal phosphate has an olivine structure. 
     
     
         27 . The lithium transition metal phosphate compound of  claim 26 , the compound is Li 1-x FePO 4 , wherein M is one or more first-row transition metals and x has a value between zero and 1. 
     
     
         28 . A lithium transition metal phosphate compound characterized in that, when used as a lithium storage electrode in a standard electrochemical cell wherein the counterelectrode is lithium metal, the compound exhibits a continuously decreasing charging current upon discharging in a potentiostatic intermittent titration (PITT) procedure at a constant overpotential of 50 mV above the open-circuit voltage of the cell, said open-circuit voltage being measured after charging to a 50% state of charge and holding for at least 12 hours. 
     
     
         29 . The lithium transition metal phosphate compound of  claim 28 , wherein said open-circuit voltage is measured after charging to a 50% state of charge and holding for at least 12 hours at 25° C. 
     
     
         30 . The lithium transition metal phosphate compound of  claim 28 , wherein said open-circuit voltage is measured after charging to a 50% state of charge and holding for at least 12 hours over a temperature range of about −20° C. to about 55° C. 
     
     
         31 . The lithium transition metal phosphate compound of  claim 28 , wherein the compound is lithium transition metal phosphate Li 1-x MPO 4 , wherein M is one or more first-row transition metals and x has a value between zero and 1. 
     
     
         32 . The lithium transition metal phosphate compound of  claim 28 , wherein the lithium transition metal phosphate has an olivine structure. 
     
     
         33 . The lithium transition metal phosphate compound of  claim 32 , the compound is Li 1-x FePO 4 , wherein M is one or more first-row transition metals and x has a value between zero and 1. 
     
     
         34 . A method of storing electrical energy comprising charging a lithium storage battery comprising the transition metal phosphate compound of  claim 28  at a C-rate of at least 2C, said C-rate being the average C-rate for a current being applied over a period of at least 5 sec. 
     
     
         35 . The method of  claim 34 , comprising charging the lithium storage battery at a C-rate of at least 5C. 
     
     
         36 . The method of  claim 34 , comprising charging the lithium storage battery at a C-rate of at least 10C. 
     
     
         37 . The method of  claim 34 , comprising charging the lithium storage battery at a C-rate of at least 15C. 
     
     
         38 . The method of  claim 34 , comprising charging the lithium storage battery at a C-rate of at least 20C. 
     
     
         39 . The method of  claim 34 , comprising charging the lithium storage battery at a C-rate of at least 30C. 
     
     
         40 . The method of  claim 34 , comprising charging the lithium storage battery at a C-rate of at least 40C. 
     
     
         41 . The method of  claim 34 , comprising charging the lithium storage battery at a C-rate of at least 50C. 
     
     
         42 . The method of  claim 34 , wherein said C-rate is the average C-rate for a current being applied over a period of at least 10 sec. 
     
     
         43 . The method of  claim 34 , wherein said C-rate is the average C-rate for a current being applied over a period of at least 20 sec. 
     
     
         44 . The method of  claim 34 , wherein said C-rate is the average C-rate for a current being applied over a period of at least 30 sec. 
     
     
         45 . A method of storing and delivering electrical energy comprising charging a lithium storage battery comprising the lithium transition metal phosphate compound of  claim 28  at a C-rate of at least 2C, and discharging at a rate of at least 2C. 
     
     
         46 . The method of  claim 45 , comprising charging at a C-rate ranging from at least 5C up to at least 50C. 
     
     
         47 . The method of  claim 45 , comprising discharging at a rate ranging from at least 5C up to at least 50C.