| As the development of microelectronic devices, research of micro-lithium batteries was conferred with the task of small size, light weight, high capability, safety and non-contamination. As a result, cathode materials become one of the most popular studied braches of micro-lithium batteries. LiNi0.5Mn0.5O2 was regarded as one of the most potentially applicated cathode materials. But there is few research report about it. So in this paper, the layer LiNi0.5Mn0.5O2 cathode film for rechargeable lithium micro-batteries was successfully prepared by a Sol-gel method. The preparation method and electrochemistry were studied.In this paper, the preparation process parameters which influence structure and electrochemical properties of LiNi0.5Mn0.5O2 thin film were studied, mainly include: solvent and concentration of LiNi0.5Mn0.5O2 precursor solution, the initial Li/(Ni+Mn) molar ration, spin-coating technology, drying temperature, annealing temperature, annealing time.Research results showed that the best precursor solution system is composed of lithium acetylacetone, nickel diacetylacetone, manganese triacetylacetone, acetic acid, n-Butanol and polyvinylpyrrolidone (PVP). Best concentration of ions is 0.3 mol/L, and dispersant PVP monomer 0.2 mol/L.The depositon parameters affected the structure of LiNi0.5Mn0.5O2 film greatly. The results revealed that smooth LiNi0.5Mn0.5O2 film without cracks could be formed under 3000rpm with the solution Cion= 0.3 mol/L, Cpvp=0.2 mol/L.The research of annealed process showed that the films contained impure phase and the surface became rough when drying at lower temperature of 280℃or higher temperature of 400℃; With the increase of annealing temperature and time, the X-ray diffraction peak of layer sturcture became stronger and the grain size growed larger. However, the grain grown abnormal large and deposition density decreased when annealing at 800℃Well crystalled films could be formed when drying at 360℃and annealing at 700℃for 30 min. The research of electrochemical properties of LiNi0.5Mn(0.5)O2 thin film showed that the thin films dried at 360℃and annealed at 700℃for 30min possessed homogeneous, dense, crack-free structure and excellent intercalation kinetics and cycling behavior. The first discharge capacity is 93.89μAh/cm2μm, and the capacity retain 86% after 50 cycles at current density of 25μA/cm2 between 3.00-4.35V. |
PDF Full Text Request