LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O 2 with morphology optimized for novel concept of 3D Li accumulator

Abstract

An array of LiNi1/3Mn1/3Co1/3O2 (NMC 111) samples with a hollow-sphere morphology enabling the use of binder-free, millimeter-thick electrodes in a battery are prepared by a combination of ball milling, hydrothermal treatment and calcination. Materials are studied by powder X-ray diffraction, nitrogen adsorption measurements, X-ray fluorescence analysis, and scanning electron microscopy. Their electrochemical performance for Li+ extraction/insertion is tested by cyclic voltammetry and galvanostatic chronopotentiometry on thin-film electrodes. Optimized materials, prepared by mechanical and thermal treatment with surface areas of 7 to 10 m2 g−1, provide charge capacity values of 141 to 156 mAh g−1. The concentration of the crystalline phase in NMC 111 materials with a hollow-sphere morphology is found to be the decisive parameter for their galvanostatic cycling stability. Hollow spheres with well-developed NMC nanocrystals and a low concentration of amorphous phase in the walls, exhibiting excellent cycling stability and charge capacity in thin-film electrodes are incorporated into a NMC/graphite 3D-battery module. This 122 Ah/451 Wh 3D-battery provides 78% of theoretical capacity and 73% of theoretical energy after 10 formatting cycles. Additionally, the battery prototype exhibits stable performance over more than 200 cycles at C/10 rate. A series of analogous 3D Li accumulators, currently assembled and tested in a pilot plant, represent the first step toward large-scale production of novel 3D Li accumulator.