To reduce cost and secondary pollution of spent lithium ion battery (LIB) recycling caused by complicated separation and purification, a novel simplified recycling process is investigated in this paper. Removal of magnesium is a common issue in hydrometallurgy process. Considering magnesium as an important additive in LIB modification, tolerant level of magnesium in leachate is explored as well. Based on the novel recycling technology, Li[(Ni1/3Co1/3Mn1/3)(1-x)Mg-x]O-2 (0 <= x <= 0.05) cathode materials are achieved from spent LIB. Tests of XRD, SEM, TG-DTA and so on are carried out to evaluate material properties. Electrochemical test shows an initial charge and discharge capacity of the regenerated LiNi1/3Co1/3Mn1/3O2 to be 175.4 mAh g(-1) and 152.7 mAh g(-1) (2.7-4.3 V, 0.2 C), respectively. The capacity remains 94% of the original value after 50 cycles (2.7-4.3 V, 1 C). Results indicate that presence of magnesium up to x=0.01 has no significant impact on overall performance of Li[(Ni1/3Co1/3Mn1/3)(1-x)Mg-x]O-2. As a result, magnesium level as high as 360 mg L-1 in leachate remains tolerable. Compared with conventional limitation of magnesium content, the elimination level of magnesium exceeded general impurity-removal requirement. (C) 2012 Elsevier B.V. All rights reserved.