Multi-stage lithiation for cathode material
A Li-ion cathode material is prepared by a multi-stage lithiation process that separates a total amount of lithium called for by the recycled battery to be used in a series of sintering stages. A leaching, ratio adjustment and coprecipitation sequence forms a cathode precursor having a predetermined ratio of metallic elements from a comingled recycling stream of Li-ion batteries. The precursor is sintered with a lithium salt in a sequence of stages, each having a portion of the total lithium quantity, for a predetermined duration and temperature. The initial sintering stage tends to define the crystallinity of the resulting active cathode material and has a particle size determined at least in part by the portion of lithium at each stage.
1 . A method of producing a cathode material from a recycled lithium-ion battery stream, comprising
leaching a black mass from the recycled lithium-ion battery stream to obtain an acidic aqueous leach solution of metal salts comprising a nickel salt, a cobalt salt, and a manganese salt in a molar ratio of metallic elements;
adjusting the molar ratio of the metallic elements in the leach solution to a selected molar ratio with additional metal salts;
co-precipitating the metallic elements and the additional metal salts from the leach solution to form a cathode material precursor comprising metallic elements selected from the group consisting of nickel, cobalt, and manganese having the selected molar ratio; and
sintering a combination of a lithium salt and the cathode material precursor in a Li:total metallic elements ratio of 1 to 1.1 by:
combining the cathode material precursor and a first portion of the lithium salt to form a first mixture having a Li:total metallic elements ratio that is less than or equal to 1,
heating the first mixture at a first sintering temperature of from 900-1200° C. for a first sintering time of from 2-10 hours to form a lithium-deficient sintered material,
combining the lithium-deficient sintered material and a remaining portion of the lithium salt to form a second mixture, and
heating the second mixture at a second sintering temperature of from 800-1000° C. for a second sintering time of from 5-15 hours to form the cathode material,
wherein the first sintering temperature is greater than the second sintering temperature and the first sintering time is less than the second sintering time, and
wherein the cathode material has a single crystal structure determined by the Li:total metallic elements ratio of the first mixture, the first sintering temperature, and the first sintering time.
2 . The method of claim 1 , wherein the black mass is leached with an aqueous acid.
3 . The method of claim 2 , wherein the aqueous acid comprises sulfuric acid.
4 . The method of claim 3 , wherein the aqueous acid further comprises hydrogen peroxide.
5 . The method of claim 1 , wherein the lithium salt is lithium carbonate or lithium hydroxide.
6 . The method of claim 1 , wherein the selected molar ratio includes less than or equal to 50 mole % nickel and the lithium salt is lithium carbonate.
7 . The method of claim 1 , wherein the selected molar ratio includes greater than 60 mole % nickel and the lithium salt is lithium hydroxide.
8 . The method of claim 1 , wherein the first mixture and the second mixture are heated in a furnace having an oxygen-containing atmosphere flow.
9 . The method of claim 8 , wherein the oxygen-containing atmosphere is air.
10 . The method of claim 8 , wherein the oxygen-containing atmosphere flow is from 0.2 to 16 SCFM.
11 . The method of claim 1 , wherein the lithium-deficient sintered material has a particle size determined by the Li:total metallic elements ratio of the first mixture, the first sintering temperature, and the first sintering time.
12 . The method of claim 11 , wherein a particle size of the lithium-deficient cathode material is from 10 to 50 microns.
13 . The method of claim 1 , further comprising jet-milling the lithium-deficient cathode material prior to forming the second mixture.
14 . The method of claim 1 , further comprising jet-milling the cathode material.