Study On Synthesis And Properties Of LiBOB

LiBOB powders were synthesized by solid-state reaction using aqueous oxalic acid, lithium hydroxide monohydrate and boric acid as raw materials. The synthesis process and phase of LiBOB were analyzed by TG-DTA and XRD to achieve optimized synthesis process. The sample synthesized under optimal conditions was characterized by XRD, FTIR and SEM. The purification of synthesized LiBOB was discussed, and the re-crystallization and solvothermal methods were compared. The solubility and conductivity of LiBOB in several common organic solvents were measured; the water content and the acid value of the samples were measured by trace amount water determination apparatus and calibration check microprocessor pH meter respectively and the storage performance of LiBOB sample was monitored.It was found that, LiBOB powder could be directly synthesized by solid-state reaction through controlling the reaction temperature and time using oxalic acid, lithium hydroxide and boric acid as raw materials. The optimal molar ratio of raw materials was H₂C₂O₄·2H2O∶LiOH·H2O∶H3BO3=2∶1∶1. The raw materials were mixed and refined by wet grinding with ethanol as grinding aids. The synthesis process included two steps, whose reaction temperature and reaction time were (90～110)℃/ (2～3)h+(220～240)℃/ (4～6)h. The XRD and FTIR results showed that the optimized process was reasonable and effective. SEM observation showed that the LiBOB particles were agglomerated to form a massive body with particle size distribution in the range of 0.5～2.5μm.The as-prepared LiBOB was purified by re-crystallization and solvothermal method, repevtively using acetonitrile as organic solvent. The results showed that the solubility of LiBOB in acetonitrile was insufficient, resulting in low yieldinig of re-crystallization and solvent-wasting. While the LiBOB sample purified by solvothermal method exhibited broadened diffraction peaks, which dissolved at higher temperature.The solubility and conductivity of as-prepared LiBOB in several common organic solvents needed to be improved. The weight loss of the sample heated at 240℃for a certain time was about 3.789% and the decline trend of water content was slowed down after a longer time. The acid content of synthesized LiBOB was 1.078×10-3. And LiBOB was still stable after short-term contact with air, but it could absorb moisture and become metamorphic after long-term contact with air.