• Energy Research

Lithium metal batteries (LMBs) are an emerging technology that promises to provide high energy density that could compensate for the energy loss of lithium-ion batteries (LIBs) at low temperatures. However, tip-driven growth during lithium deposition remains a problem for LMBs at low temperatures, which should be mitigated for improved cyclability and safety. Tailoring lithium metal nucleation with lithiophilic substrates has shown effectiveness in improving cycling performance at room temperature, but the investigation at low temperatures is limited. For this work, promoting homogeneous lithium nucleation by implementing a lithiophilic substrate, lithiated graphite (LiC6), the adverse effects of low temperature on Li cycling were alleviated in a model electrolyte. This lithiated graphite substrate provided 4.2% and 4.5% higher measured coulombic efficiency for Li cycling compared to copper at −20 °C and −40 °C, respectively, which demonstrated higher specific capacity and improved cyclability for 2× excess Li||Ni0.6M0.2C0.2O2 full cells.

The reversibility of Li metal batteries suffers beneath 0 °C due to a heightened charge-transfer barrier. Herein, the introduction of ion-pairs within the electrolyte is shown to improve this behavior, enabling hundreds of cycles down to −40 °C.

Direct regeneration of spent Li-ion batteries based on the hydrothermal relithiation of cathode materials is a promising next-generation recycling technology. In order to demonstrate the feasibilit...

Lithium metal batteries (LMBs) hold the promise to pushing cell level energy densities beyond 300 Wh kg-1 while operating at ultra-low temperatures (< -30°C). Batteries capable of both charging and discharging at these temperature extremes are highly desirable due to their inherent reduction of external warming requirements. Here we demonstrate that the local solvation structure of the electrolyte defines the charge-transfer behavior at ultra-low temperature, which is crucial for achieving high Li metal coulombic efficiency (CE) and avoiding dendritic growth. These insights were applied to Li metal full cells, where a high-loading 3.5 mAh cm-2 sulfurized polyacrylonitrile (SPAN) cathode was paired with a one-fold excess Li metal anode. The cell retained 84 % and 76 % of its room temperature capacity when cycled at -40 and -60 °C, respectively, which presented stable performance over 50 cycles. This work provides design criteria for ultra-low temperature LMB electrolytes, and represents a defining step for the performance of low-temperature batteries.