Hanyang team develops new Li-metal battery for EV operating conditions; outperforms LMBs in the literature
Researches at Hanyang University in Seoul, S. Korea, have developed a Li-metal battery (LMB) (specifically, a Li/NCM battery) designed with EV operating requirements in mind that they say outperforms LMBs reported in the literature to date. The new LMB is capable of fast charging while delivering a high energy density. Their open-access paper appears in the RSC journal Energy & Environmental Science.
Li metal, with theoretical capacity of 3860 mAh g−1, is of great interest as an anode for high-energy-density batteries. When used in electric vehicle (EVs), the LMB obviously needs to survive the practical operating conditions. In general, however, fast charging accelerates the deleterious dendritic growth of Li and thus aggravates the parasitic reactions between the Li–metal anode and electrolyte.
Li dendrite growth induces poor cycling efficiency at fast charging rates and at high active material loadings, thereby hindering the application of LMBs in EVs.
Illustration of the proposed LMB concept in comparison with that of a conventional LMB. (a) Summary of conventional LMBs and the LMB concept. (b) Comparison of the cyclability of the proposed LMB with previously reported cyclability values under practical test conditions (current density: ≥2 mA cm−2 and capacity loading: ≥2 mAh cm−2. Hwang et al.
The Hanyang team used a modified organic electrolyte and pretreatment of Li metal to form a stable and robust solid electrolyte interphase layer on the Li anode surface.
Pretreatment of the Li–metal anode with LiNO3 adds a prior Li2O-rich SEI layer that provides the required mechanical strength to prevent premature SEI layer breakdown.
Combining that with an Al-doped full-concentration-gradient Li[Ni0.75Co0.10Mn0.15]O2 cathode, the researchers built an LMB capable of an areal capacity of 4.1 mAh cm−2 with unprecedented cycling stability over 300 cycles at a high current density of 3.6 mA cm−2.
Cycled in a pouch-type cell for 500 cycles, the LMB retained 90% of initial capacity.
We believe that this work marks an important step in the design of an LMB to effectively stabilize the Li–metal surface. In addition, this work also re-highlights the importance of choosing an optimal cathode material in practical applications of an LMB.
Jang-Yeon Hwang, Seong-Jin Park, Chong S. Yoon and Yang-Kook Sun (2019) “Customizing a Li–metal battery that survives practical operating conditions for electric vehicle applications” Energy Environ. Sci. doi: 10.1039/C9EE00716D