Failure mechanism and behaviors of lithium-ion battery under high discharging rate condition

To date, the widespread utilization of lithium-ion batteries (LIBs) has created a pressing demand for fast-charging and high-power supply capabilities. A comprehensive understanding of the attenuation mechanism of LIBs at high discharging rates is essential for enhancing battery control, and establishing an optimal guideline to designing batteries with excellent high-rate properties. Herein, a kind of commercial LiNi0.5Co0.2Mn0.3O2/graphite battery is explored under various high-rate discharging procedures. As always, the rate of capacity decay is directly proportional to the discharging rate. In comparison to the initial capacity, the effective capacities of each battery decrease by 1.99 Ah, 1.45 Ah, and 2.52 Ah after undergoing 4000 cycles at various discharging rates (5C, 10C, 20C) while being charged at a constant rate of 1C under room temperature conditions, the corresponding capacity retention rates are approximately 75 %, 79.1 %, and 64.8 %. The detailed exploration is conducted by analysis the morphology and composition of the electrodes after post-mortem, which reveals that reveals that the LiNi0.5Co0.2Mn0.3O2 cathode experiences exacerbated delamination and pulverization of its crystalline structure due to fast extraction/insertion of Li-ions, while the graphite anode peels into discontinuous layers, indicating that the loss of active material in LIBs is the primary failure factor during high discharge rates. Additionally, minor factors include the loss of active Li-ions caused by devitalized lithium-compounds formation within the active materials. Consequently, this study will contribute to providing solutions for enhancing battery safety and reliability under extreme operating conditions and environments.