Study On Novel Aqueous Rechargeable Lithium Batteries

Currently, energy industy is facing challenges due to the fast developing science and technology. The reserves of coal, oil, natural gas and other traditional non-renewable energy decreased rapidly because of the excessive use of energy. At the same time, environment pollution is increasing. Energy and the pollution become the two major problems in today’s society. And to develop green renewable energy has been an urgent subject. Wind, solar and other new energy industry can not meet the needs of the application at any time due to its natural and seasonal properties, therefore, to develop new energy sources, we must develop new energy storage devices.Aqueous rechargeable lithium battery (ARLB) is one of major research directions in energy field because of its safety, long cycle life property, high power density and low cost. It is the most suitable energy storage and energy conversion device for electric cars, solar energy and wind power plants. However, ARLB does have its innate shortcoming due to the narrow electrochemical window in aqueous solution. The theoretical decomposition voltage in aqueous solution is only1.229V and it is almost imposible for ARLB to reach a voltage above2V. This weakness leads to a low energy density of ARLB which can not compete with traditional lithium-ion batteries.Therefore, in order to overcome this drawback, this dissertation proposes a novel aqueous rechargeable lithium battery system. Rearch is divided into two parts:first, with the two films coated on the surface of lithium metal, we obtained an anode which has a sandwich-like structure and is stable in aqueous solution; second, we combined some cathode material with our anode, and got a series of new high energy density aqueous rechargeable lithium battery systems, and there electrochemical properties were characterized.Gel film and LISICON film were applied to coat on the surface of lithium metal. Finnally, we obtained a coated lithium anode. The experiment shows, lithium ion can successfully transport through anode in Li2SO4aqueous solution. The layer of LISICON film can prevent the H+from transporting into the surface of lithium metal and reacting into H2. The middle layer of gel film can ensure the good interfacial contact and transporte lithium ion smoothly. At the same time, the gel film will also decrease the produce of lithium dendrite.Lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate were used as a cathode active material to combine entire battery systems with coated lithium anode respectively. By electrochemical tests, we found that the entire battery systems with the latter three materials can have very stable charge and discharge cycles. The performance of Li/LiMn2O4and Li/LiFePO4aqueous rechargeable lithium battery systems performance are particularly prominent. Simply calculated from active materials, the energy density of these two systems are446Wh/g and342Wh/g respectively, these values are greater than the existing aqueous rechargeable lithium batteries by more than5times.