Soft-contact conductive carbon enabling depolarization of LiFePO4 cathodes to enhance both capacity and rate performances of lithium ion batteries

Abstract

Conductive nanocarbons generally are used as the electronic conductive additives to contact with active materials to generate conductive network for electrodes of commercial Li-ion batteries (LIBs). A typical of LiFePO 4 (LFP), which has been widely used as cathode material for LIBs with low electronic conductivity, needs higher quantity of conductive nanocarbons to enhance the performance for cathode electrodes. In this work, we systematically studied three types of conductive nanocarbons and related performances in the LFP electrodes, and classify them as hard/soft-contact conductive carbon (named as H/SCC), respectively, according to their crystallite size, surface graphite-defect, specific surface area and porous structure, in which SCC can generate much larger contact area with active nano-particles of cathode materials than that of HCC. It is found that LFP nanocrystals wrapped in SCC networks perform significantly enhanced both capacity and rate performance than that in HCC. Combined experiments with multiphysics simulation, the mechanism is that LFP nanoparticles embedded in SCC with large contact area enable to generate higher depolarized effects with a relatively uniform current density vector (i s) and lithium flux vector (N Li) than that in HCC. This discovery will guide us to how to design LIBs by selective using conductive carbon for high-performance LIBs.

Urea and Ethylene Glycol‐Assisted Solvothermal Synthesis of Spheroidal LiFePO4/C Nanoparticles as a Cathode Material for Lithium‐ion Batteries

“…The extraction/insertion of Li‐ions needs the small impedance during the charge/discharge process . It is believed that the lower R ct of LFP‐18 h‐C‐1 derives from the formed carbon network and the suitable size, which is consistent with the reported literature . Seen from CV and EIS synthetically, LFP‐18 h‐C‐1 samples display the minimal polarization, which seems to be in tune with the results of other tests.…”

Cellulose‐Templated, Dual‐Carbonized Na3V2(PO4)3 for Energy Storage with High Rate Capability

“…As shown in Figure A , the two intense peaks at 1350 (D) and 1590 cm −1 (G) originated from sp 2 ‐carbon species, and the other two peaks at 1180 and 1490 cm −1 were assigned to sp 3 ‐type carbon. The relative contents of sp 2 and sp 3 carbon were estimated from the integrated area ratio of sp 2 and sp 3 peaks ( A sp2 / A sp3 ) according to the literature . We found that the content ratio of the sp 2 and sp 3 carbon of CS‐NVP, C‐NVP, and S‐NVP were 4.34, 3.64, and 3.53, respectively.…”

Choice for graphene as conductive additive for cathode of lithium-ion batteries

“…Carbon materials with different structures and dimensions have been widely used as conductive additives for most commercial LIBs due to their high electronic and thermal conductivity, good chemical stability and light weight [9,[11][12][13][14] . Besides the conventional carbon materials, such as carbon black and graphite powder, new carbon materials with higher conductivity, such as carbon nanotubes, vapor grown carbon fibers and graphene also show great potential for the application as conductive additives in recent years [14][15][16][17][18] .…”