Lithium polyacrylate binder enables high-performance LiNi0.5Mn1.5O4 lithium-ion batteries

As a high voltage cathode material for lithium-ion batteries (LIBs), LiNi 0.5 Mn 1.5 O 4 (LNMO) features a three-dimensional Li + diffusion network that enables fast bulk diffusion. However, at high operating voltages, electrolyte decomposes significantly and form thick cathode electrolyte interface (CEI) film, which slows down Li + transport at the electrode interface and makes it the rate limiting step for Li + extraction and insertion. In this work, low molecular weight lithium polyacrylate (LiPAA) is synthesized by replacing the hydrogen in polyacrylic acid (PAA) with lithium, and used as the binder of LNMO cathode, which can not only create a more uniform coating and conductive network to accelerate interfacial Li + transport, but also protects the electrode and alleviates the interfacial transport limitation of Li + . After 1000 cycles under a 5C high-rate current, the electrode using the LiPAA based binder retained 87.8 % (102.1 mAh/g) of the initial capacity. Even under a 20C super high-rate test, it delivered a discharge capacity of 74.67 mAh/g. This work proves that the rational design of binder is beneficial to electrochemical performance of lithium-ion batteries.