Lithium nickel cobalt manganese oxide (LNCM) is a key positive electrode material for ternary lithium batteriesIt has a higher capacitance and lower cost than lithium iron phosphate batteries.Chlorine (Cl) is an impurity that may affect battery efficiency and storage capacityTherefore, according to the "Standard for Colored Metal Industry of the People's Republic of China" (YS/T928.1-2013), for quality control, it is necessary to monitor the presence of Cl in LNCM.

The conventional testing methods include silver nitrate turbidity method and ion selective electrode method, but these two techniques have low sensitivity and poor detection limit, about 0.01%. By contrast,Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is a powerful elemental analysis technique with excellent detection limits and very high sensitivity, making it ideal for determining Cl in positive electrode materials and their precursors.

There are some challenges in using ICP-MS to determine Cl in the positive electrode and its precursor, such as the low ionization efficiency of Cl and the matrix effect caused by the high total dissolved solids (TDS) (the latter problem can be effectively solved by dilution). Compared to liquid dilution methods that require additional solvents and pre-treatment time, some ICP-MS systems provide online gas dilution, which can bring advantages to practical applications by reducing analysis errors, contamination, and sample preparation time.