NMR evidence for the charge-discharge induced structural evolution in a Li-ion battery glass anode and its impact on the electrochemical performances

Highlights: • NMR revealed the structural evolution in a LIB Te-V-P-O glass anode during cycling. • The glass network was fully disassociated during the charge/discharging cycling. • Such network disassociation led to formation of nano-clusters. • The size of the nano-clusters was determined using a self-developed NMR method. • The nano-clusters greatly enhanced both rate capability and cycling stability. Recently it has been demonstrated that the electrochemical performances of semiconducting amorphous anodes for Li-ion batteries (LIBs) can be greatly enhanced by the discharging/charging induced nanocrystals. However, the structural origin of those nano-domains remains elusive, although it is critically important for designing superior glass anodes for LIBs. In this work, we probe the local structural evolution in a glass anode for LIBs during cycles by means of the state-of-the-art solid-state nuclear magnetic resonance (SSNMR). The structural evolution is manifested as the disassociation of the structural network into isolated units, followed by formation of different types of nano-domains with a high degree of order. These domains are highly favorable for rate capability and long-term cycling stability. From SSNMR and electrochemical characterizations, we have obtained a clear picture about the detailed redox reactions. These findings provide a chemical principle that is helpful for designing the stable glass electrodes for high-performance LiBs.