The influences of temperature and cell operation conditions on Li metal deposition in lithium ion batteries were studied by in-situ solid-state Li-7 nuclear magnetic resonance (NMR) spectroscopy. The rates of Li metal deposition during the low-temperature cycle with two charge-discharge operation modes, i.e., continuous current and pulse current, were estimated for temperatures of 5, 0, and -5 degrees C. Close values of activation energies were obtained for the capacity fading rate and the Li metal deposition rate, suggesting that Li metal deposition is the main cause of capacity fading in low-temperature cycles. The amounts of Li stored in the negative electrode and Li metal deposited during the low-temperature cycle were estimated and are discussed to understand the capacity fading mechanism. The pulse current mode cycle did not lead to any Li metal deposition at low temperatures. (c) The Author(s) 2017. Published by ECS. All rights reserved.