If you want to quantify lithium content in battery materials, ICP is the only technique that gives you a defensible, absolute number.
Not XRD.
Not SEM-EDS.
For bulk lithium concentration across cathode active material (CAM), electrolyte salts, precursors, or black mass: ICP-OES is the industry standard.
What is ICP-OES?
ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) is an analytical technique used to determine the elemental composition of materials. It works by introducing samples into a plasma that excites elements, causing them to emit light at characteristic wavelengths that can be measured to quantify elemental concentrations.
Where ICP-OES Is Used in Battery Materials
ICP-OES is applied across the entire lithium-ion battery lifecycle:
1. Resource Extraction
Quantifying lithium in ores and brines, verifying purity of lithium salts (carbonate, hydroxide, chloride), and detecting refining impurities.
2. Battery Manufacturing
Confirming stoichiometry in cathode materials (LCO, LFP, NMC), screening anode impurities (Fe, Cu, Na, etc.), testing electrolyte salt contamination, and ensuring regulated elements remain below limits.
3. Battery Recycling
Assaying black mass to quantify valuable metals (Li, Ni, Co, Mn) and contaminants (Fe, Cu, Zn) to support recovery economics.
ICP-OES simultaneously measures major elements (>1 wt%) and trace impurities (ppm levels), making it essential for quality control, compliance, and process optimization from mine to recycling.
Sample Preparation Is Half the Experiment
ICP only works on solution.
Most battery materials are solids.
That means digestion defines reality.
Aqua Regia Digestion
For analyzing battery materials, particularly recycled "black mass" samples, aqua regia (nitric + hydrochloric acid) digestion is a critical sample preparation step.
If digestion is incomplete → ICP result is incomplete.
Preparation and interpretation are so important to ICP, that it becomes more of an art than a science.
These solutions are LCO, LFP, and NMC that have been analyzed by ICP-OES: which is which???
What It Actually Tells You
ICP-OES gives you bulk elemental composition in solution after digestion.
It does not tell you:
Whether lithium is structurally where it should be
Whether cation mixing is present
Whether electrochemical balance is intact
Whether dissolution during cycling is kinetically meaningful
“Correct ratio” is not the same as “correct structure.”
ICP-OES is a mass balance tool.
It tells you how much lithium is there and how much of everything else came along for the ride. That matters. A lot.
But lithium content alone does not guarantee electrochemical performance, structural integrity, or manufacturing robustness. It is one piece of the system.
Used correctly, ICP anchors your material in quantitative reality.
Used casually, it creates false confidence with too many significant figures.
In battery manufacturing, absolute numbers matter.
Understanding what those numbers mean matters more.
That’s the difference between reporting composition and building a cell that actually works.
Some Resources We Love:
I was tempted to subject you all to a new series about founding a battery company. Then I remembered that you might be interested in C-rates, but not C-suites. So I started a separate podcast called Up In Her Biz.