Polyacrylonitrile-polyvinylidene fluoride as high-performance composite binder for layered Li-rich oxides

Layered lithium-rich Oxides (LLROs) suffer from serious capacity fading during the cycling especially when the size is in sub-micron or nanoscale. Here we report the polyacrylonitrile (PAN) as a binder to maintain the capacity of LLROs sized ∼200 nm, the combined PAN with polyvinylidene fluoride (PVDF) achieve excellent cycle and rate performance as the composite binder taking advantages from both PAN and PVDF. The capacity retention of PAN-PVDF electrode after 40 cycles is 89.6%, comparing to the 77.5% of PVDF electrode and 85.1% of PAN electrode. The SEM images pronouncedly illustrates that PAN-PVDF as composite binder holds the active material on the laminates firmly, resulting few cracks and voids. The electrochemical impedance spectra indicate that averting those voids and cracks lead to lower resistance. The composite binder has played a significant role in improving the cycling and rate performance of LLROs.