Synthesis Of The Postive Materials Of Manganese Dioxide & Vanadium Oxide And Their Electrochemical Performance In The Lithium Battery & Lithium-ion Battery

The electrochemical performance of batteries depends on the charge/dischargeperformance of the positive materials. In this thesis, several kinds of methods selectedwere used to prepare the positive materials of the lithium batteries and lithium-ionbatteries. The relationship between the electrochemical performance and preparedcondition was studied. These research works have provided us with new methods for thepreparation of the new batteries materials and summarized below:(1). Generally speaking, the positive electrodes of the commercial batteries wereprepared by using the complex slurrying-coating process, which electrochemicalperformance may be obviously affected by the preparation process. In this field, incompare to the slurrying-coating process, the electrolysis method can control easily theelectrode thickness with lower cost. The electrochemical performance of positiveelectrodes can also be improved by controlling the electrolysis condition. The thesis aimsto prepare manganese dioxide-carbon electrode directly with the structure of tetragonalMnO₂(space group: P42/mnm) and vanadium oxide-carbon electrode with KV₅O_13-x type.The manganese dioxide-carbon electrode exhibits a discharge capacity of 219 mAh/g at adischarge current of 0.1C; the vanadium oxide-carbon electrode exhibits a capacity of 238mAh/g. The experimental results show that the samples particles on the as-preparedpositive electrode can combine with graphite electrode without the using of the adhesives.(2) The spinel LiMn₂O₄ possesses many advantages, such as cheap, friendly toenvironment and discharge with large current density. However, its main disadvantagesare in the field of storage. Such as bad storage performance, especially badelectrochemical performance in the elevated temperature. This thesis is planning toimprove the electrochemical performance of the spinel LiMn₂O₄ by using the dopingmethod. The as-prepared sample with the theoretical composition ofLi_0.95Na_0.1Mn_1.9Co_0.1O₄ exhibits a discharge capacity of 93.9mAh/g at the 1st cycle, and101.1mAh/g at the 530th cycles. The sample charge-discharged at a elevated temperatureexhibits a initial capacity of 116.1mAh/g with high charge/discharge efficiency.