Fast charging of lithium-ion batteries at all temperatures

Abstract

Fast charging is a key enabler of mainstream adoption of electric vehicles (EVs). None of today's EVs can withstand fast charging in cold or even cool temperatures due to the risk of lithium plating. Efforts to enable fast charging are hampered by the trade-off nature of a lithium-ion battery: Improving low-temperature fast charging capability usually comes with sacrificing cell durability. Here, we present a controllable cell structure to break this trade-off and enable lithium plating-free (LPF) fast charging. Further, the LPF cell gives rise to a unified charging practice independent of ambient temperature, offering a platform for the development of battery materials without temperature restrictions. We demonstrate a 9.5 Ah 170 Wh/kg LPF cell that can be charged to 80% state of charge in 15 min even at -50 °C (beyond cell operation limit). Further, the LPF cell sustains 4,500 cycles of 3.5-C charging in 0 °C with <20% capacity loss, which is a 90× boost of life compared with a baseline conventional cell, and equivalent to >12 y and >280,000 miles of EV lifetime under this extreme usage condition, i.e., 3.5-C or 15-min fast charging at freezing temperatures.

Effect of Anode Porosity and Temperature on the Performance and Lithium Plating During Fast‐Charging of Lithium‐Ion Cells

“…Commensurate with visual observations shown in Figure 7, the model predicts significant amounts of lithium plating except for cells operating at 50 °C. Increasing temperature significantly mitigates lithium plating due to improvements in the electrolyte transport properties [ 12,13,29 ] and graphite transport/kinetic properties. Further model development is required to better understand the reversibility of the lithium‐stripping process and the effect of this on cell lifetime.…”

Irreversibility at macromolecular scales in the flake graphite of the lithium-ion battery anode

“…Here, the graphite is cycled from the open circuit potential (OCP) to 5 mV at a rate of 1 mV/s, held at a constant voltage (CV) of 5 mV for 3.5 hours, and then returned to the OCP at a rate of 0.5 mV/s. Thus a voltage ramp replaces the constant current (CC) phase of the CCCV 31 charging protocol used for both standard and fast charging. Relative to CC, the voltage ramp gives superior predictability when testing small, individual graphite flakes whose electrochemistry might not dominate the parasitic chemistry on, e.g., the metal electrode.…”

“…Relative to CC, the voltage ramp gives superior predictability when testing small, individual graphite flakes whose electrochemistry might not dominate the parasitic chemistry on, e.g., the metal electrode. These scanning conditions were chosen to minimize degradation of the graphite 32 and to represent fast 31 but not extreme charging conditions. Full charge occurs in about an hour, while the max current of 15 nA, sustained, would lithiate the flake in 10 minutes.…”

Evaluation of Present Accelerated Temperature Testing and Modeling of Batteries

“…Only the capacity losses after the first 2 years' storage at 23 • C and 40 days' storage at 60 • C were picked, respectively, to calculate the degradation rates, then extrapolated the activation energy. The remaining data is not used in this case, and similar ways of validating the Arrhenius model and extracting the model parameters are seen in [33]. However, when the capacity losses at 23 • C from the 3rd year to the 5th year, and 60 • C from the 60th day to the 100th day are chosen for calculation, the AF and activation energy are changed to 15.6 and 0.632 eV, respectively.…”