Nano LiMnBO3, a high-capacity cathode material for Li-ion batteries

Nano h-LiMnBO3 with an average particle size of similar to 20 nm has been synthesized by a sol-gel method for the first time. The nanoscopic material is obtained at temperatures of 350 degrees C and below, whereas the higher temperature synthesis above 500 degrees C results in the microcrystalline phases that have poorer electrochemical performance. In situ carbon coating of LiMnBO3 particles by carbonization of propionic acid right during the synthesis of nano h-LiMnBO3 (4.2 wt-% carbon) provides a conducting surface. Carbon particles partially cover the surfaces of nanorods and disperse among nano crystallites enhancing the electronic transport in the electrode material. The sol-gel synthesized nano h-LiMnBO3 yields a first discharge capacity of 136 mAh g(-1) within a window of 4.7-1.7 Vat C/20 rate. This is considerably higher than previously reported. Further improvements of the system are realized by preparing a composite electrode of nano h-LiMnBO3 with reduced graphite oxide that delivers a high first discharge capacity of 145 mAh g(-1) at C/20 rate and retaining a discharge capacity of 111 mAh g(-1) at the 10th cycle. An increase of capacity is expected to be reached by further reduction of the particle size and size spread as well as by optimizing the conductive coating of the nano particles. (C) 2012 Elsevier B.V. All rights reserved.