RSF Project #19-19-00175

(2019-2021)

The need to use flammable organic electrolytes in lithium-ion batteries together with strong oxidants and reducers in the composition of cathode and anode materials can cause a fire and even an explosion of the battery in the event of emergency situations during its operation. Such abnormal situations usually include overcharging, overcharging, internal and external short circuits. These processes lead to thermal runaway of LIB, due to which the battery itself can collapse and catch fire, leading to the destruction of the entire product as a whole and traumatizing consumers, which is especially critical when using LIB batteries as energy sources for vehicles. The occurrence of emergency situations is usually associated with external factors that are difficult to predict and prevent, therefore, safety issues are solved using the electronic monitoring and control systems (IMS) built into the product, which provide mechanisms for turning on / off the battery in operating mode and in an emergency situation. The disadvantage of this approach is the disproportionate increase in the cost of the control system for high-power batteries due to the need to work with currents of 10-100 kA, as well as the probability of failure of the control system itself. Unlike electronic systems, chemical protection mechanisms are more resilient and more scalable (since their implementation depends on the current density per unit electrode surface, and not on the total current in the system). Therefore, the creation of a mechanism that solves safety issues by modifying battery materials is an urgent task that is critical for the development of technology. The goal of the project is to ensure that the circuit inside the lithium-ion battery is opened in the event of abnormal operating conditions. For this, it is proposed to create a protective sublayer between the cathode current collector and the active mass. The resistance of this layer should sharply increase when the cathode potential goes beyond the window of permissible values ​​and / or exceeds the threshold temperature, while such changes should be reversible. Then, in the event of an abnormal operating mode of the battery, the cathode material will become isolated from the down conductor and further development of the abnormal situation and thermal acceleration of the battery will not occur. When the external cause of the abnormal operation is eliminated (faulty charger, short circuit source, etc.), the conductivity of the protective sublayer will be restored, and the battery will be suitable for further use. To achieve the set goal of the project, the tasks will be solved to create materials that have the required nature of the dependence of conductivity on the electrode potential and temperature, suitable for applying thin continuous layers on aluminum substrates (down conductors) and stable under normal LIB operation. The novelty of the proposed approach lies in the use of a sublayer with potentioresistive properties as a way to protect LIB from overcharge and deep discharge, as well as in the use of previously undescribed polymers as a potentioresistive sublayer material.

Improving the safety of lithium-ion batteries

Publications

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