| Lithium manganese dioxide cell is a high performances chemical power source, and it's one of the three kinds of primary lithium cells which have been widely used. Recently, researchers pay much attention to how to improve the electrochemical performance of this system, because of its outstanding advantages (no obvious voltage lag, credible safety). As a traditional active material, manganese dioxide has been widely used in cells, but its properties are different between organic electrolytes and aqueous electrolytes. In this work, effects of the positive electrode,includes the positive active material of manganese dioxide, the conducting additive and the electrode-preparing technology on characteristics of the electrode had been investigated detailedly.Manganese dioxide with different crystal structure had been prepared by sol-gel process and solid reaction method. XRD analysis, constant current discharge measurement and other testing methods were employed to study their physical and electrochemical properties. The discharge capacity ofλ-MnO2 was 227.5mAh/g at 0.2mA/cm2,andα-MnO2 had a higher capacity (259.8mAh/g).The chemical manganese dioxide supplied by Hunan Haili Chemical Industry Co., Ltd (HLC) showed a discharge capacity 268.5mAh/g at 0.2mA/cm2. The discharge capacity at 0.2mA/cm2 of the ion-doped manganese dioxide supplied by Xiamen University could reach to 282.61mAh/g, and such material had a high smooth voltage plateau. All of them mentioned above were positive materials with better electrochemical propertice for lithium manganese dioxide cell.Five kinds of conducting additives were compared on powder electrical conductivity: electrical conductivity of acetylene black was close to that of SP; the electrical conductivity of KS15 was around 320μ?·m similar to that of expanded graphite; VGCF exhavited the minimal electrical conductivity (0.6μ?·m) among the five materials. The cells with mixed conducting additive of acetylene black and graphite (expanded graphite, KS) showed the maximal discharge capacity. The discharge properties of the electrodes with mixed conducting additive of carbon fiber (VGCF) and carbon black SP were better than that with acetylene black and expanded graphite at 0.2mA/cm2. The former one had a voltage plateau about 60mV higher than the latter one, and its discharge time increased by 9.12 hours. When discharged at 5mA/cm2, the discharge capacity properties of the former one were improved obviously: the discharge voltage plateau increased about 100mV than the latter one; the discharge time prolonged by 52%.To get an electrode with better performances, the coating technology was adopted. The partical size D50 of the positive materials must be controlled to samller than 20μm, thus the surface of electrodes would be smooth and well-proportioned. The electrodes were prepared by two methods: coating and pressing-film method. The maximal exported power of the former was more two times larger than the latter, and the utilization factor of active material could be enhanced by 30% at high discharge rate.The utilization factor of the active material could be enhanced by 50% for the electrode with mixed conducting additive of carbon fiber (VGCF) and carbon black SP, and the output current density of the electrode made by coating technology could be enhanced by 86% compared to the electrode prepared by traditional technology,.
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