Stable and ultrafast lithium storage for LiFePO4/C nanocomposites enabled by instantaneously carbonized acetylenic carbon-rich polymer

The low electronic conductivity and poor Li thorn diffusion coefficient of conventional LiFePO4 (LFP) materials severely impede its high-rate applications for lithium-ion batteries (LIBs). To break these limits, one novel poly(1,3-diethynylbenzene) (PAB) acetylenic carbon-rich polymer with extremely high-carbon content (96.75 wt%) and good solubility has been prepared by an oxidative coupling reaction. One definite advantage is that this carbon-rich PAB polymer will release, upon pyrolysis, very low amounts of gas, forming therefore uniform and dense highly conductive carbon network. Besides, the specific resistivity of continuous PAB-C layer can be as low as similar to 0.01 Omega cm, which can effectively improve electrical conductivity and maintain mechanical integrity of LFP cathode. As a result, the prepared LFP@PAB-C nanocomposites with approximately 3.8 wt% carbon content and 2.5 nm carbon layer exhibit an excellent high-rate capability, e.g. even at a considerable discharge rate of 50 C, while the capacity can still be remained at 129.6mA h g(-1). Moreover, the LFP@PAB-C nanocomposites also reveal a remarkable cycling stability with as high as 100.6% capacity retention at 20 C over 1000 cycles. This kind of LFP@PAB-C composite was demonstrated to be an ideal cathode material for high-power LIBs. (C) 2019 Elsevier Ltd. All rights reserved.