Operando Analysis of Gas Evolution in TiNb<sub>2</sub>O<sub>7</sub> (TNO)-Based Anodes for Advanced High-Energy Lithium-Ion Batteries under Fast Charging
Dhrupad Parikh, Linxiao Geng, Hailong Lyu, Charl J. Jafta, Hansan Liu, Harry M. Meyer, Jihua Chen, Xiao‐Guang Sun, Sheng Dai, Jianlin Li
Abstract
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.