Optimizing Lithium-Ion Batteries for Extended Extreme-Fast Charging: Strategies to Prevent Lithium Plating without Compromising Charge Acceptance
Authors: Tanim Tanvir R. , Colclasure Andrew M. , Yang Zhenzhen , Gering Kevin L. , Dufek Eric J. , Dunlop Alison R. , Jansen Andrew N. 
Published: December 2024

Enabling Extreme Fast Charging (XFC), particularly achieving a 10-minute charge cycle, represents a significant technological milestone. Accomplishing this objective necessitates a comprehensive comprehension of the intricate interactions inherent within Lithium-ion batteries (LiBs), encompassing their operational dynamics and aging characteristics. Realizing XFC entails the implementation of diverse solutions, such as sophisticated materials-to-electrode design methodologies and meticulously devised charging protocols. This presentation aims to delineate various solution strategies that have demonstrated efficacy in facilitating XFC in LiBs across numerous charge-discharge cycles in moderate-loading cells (3 mAh/cm2 anode versus 2.7 mAh/cm2 cathode). Furthermore, it will investigate aging phenomena at various scales, thereby contributing to a deeper comprehension of this technological advancement.

The cell assemblies investigated in the forthcoming study employed multiple solution strategies, including: (1) Preference for NMC811 over NMC532 as the cathode material, (2) Adoption of an optimized carbon binder domain in NMC811, (3) Implementation of a dual-layer anode (DLA), (4) Transition to a higher-pore-volume separator, (5) Integration of an advanced electrolyte such as B26, and (6) Application of advanced charge protocols. These strategies collectively augment lithium-ion transport within the cell, consequently mitigating overall cell overpotential losses and diminishing cell degradation across diverse length scales. As a result, they effectively inhibit lithium plating even after undergoing hundreds of charging cycles.

Cells implementing the six solution strategies attained an 87.3% charge acceptance within a 10-minute timeframe, employing a 6C CC-CV charge protocol with a cutoff voltage set at 4.1V. Following 600 cycles, these cells exhibited an 11.5% degradation rate, with no discernible evidence of lithium plating, equating to a driving range equivalent to 171,000 miles and a charging speed of up to 26 miles/min.

XFC employing a higher charge cutoff voltage of 4.15V yielded a marginally improved charge acceptance ranging from 3.5% to 4.8% for two advanced charge protocols, namely Material Stress Reduction (MSR) and Voltage Ramp (VR), albeit with accelerated aging. Despite modifications to the MSR protocol, it did not entirely mitigate lithium plating; however, the VR profile achieved a noteworthy 92.1% charge acceptance within 10 minutes, experiencing a 13.9% capacity fade after 600 cycles at a 4.15V charge cutoff, thereby avoiding lithium plating. This translates to a fast-charge range spanning from 171,000 to 181,000 miles, satisfying current prevailing electric vehicle (EV) warranty and longevity objectives, with a charging rate ranging from 26 to 27 miles/min, in alignment with the Department of Energy's XFC goal of 20 miles/min.

The findings of this study confirm the advantages of integrating various solution strategies to enable XFC. These encouraging outcomes pave the way for achieving a 10-minute XFC capability in energy-optimized cells with loading capacities of ≥4 mAh/cm2.