posted on 2021-11-15, 21:13authored byDhrupad Parikh, Linxiao Geng, Hailong Lyu, Charl J. Jafta, Hansan Liu, Harry M. Meyer, Jihua Chen, Xiao-Guang Sun, Sheng Dai, Jianlin Li
TiNb2O7 (TNO) is regarded as one of the promising
next-generation anode materials for lithium-ion batteries (LIBs) due
to its high rate capabilities, higher theoretical capacity, and higher
lithiation voltage. This enables the cycling of TNO-based anodes under
extreme fast charging (XFC) conditions with a minimal risk of lithium
plating compared to that of graphite anodes. Here, the gas evolution
in real time with TNO-based pouch cells is first reported via operando
mass spectrometry. The main gases are identified to be CO2, C2H4, and O2. A solid–electrolyte
interphase is detected on TNO, which continues evolving, forming,
and dissolving with the lithiation and delithiation of TNO. The gas
evolution can be significantly reduced when a protective coating is
applied on the TNO particles, reducing the CO2 and C2H4 evolution by ∼2 and 5 times, respectively,
at 0.1C in a half-cell configuration. The reduction on gas generation
in full cells is even more pronounced. The surface coating also enables
20% improvement in capacity under XFC conditions.