The gelation of commercial lithium iron phosphate (LiFePO4) in water-based slurry and its corresponding mechanism are studied. When a large portion of the inner LiFePO4 of commercial carbon-coated LiFePO4 is exposed, the powder becomes polar and its surface possesses numerous hydroxyl groups that tend to form a three-dimensional gel-like structure via hydrogen bonding. (C) 2013 Elsevier B.V. All rights reserved.