What are the effects of new negative materials on the life of rechargeable battery capacity

A team from the Japan Institute of Materials Research(NIMS) has successfully synthesized alternating materials of manganese oxide nanoparticles and graphene. As a negative electrode material for lithium and sodium ion rechargeable batteries, the composite material can increase the battery charge and discharge capacity more than twice, and can extend the service life, solving the problem that the capacity and life can not be obtained.

High capacitance is one of the targets of secondary batteries. At present, the negative electrode uses carbon materials. Theoretically, the transition metal oxides have high capacity and are expected to become substitutes for carbon materials. In particular, manganese oxide with a layered structure is stripped into a single-molecule thick nanometer sheet. It is used as a negative electrode and the surface is all active, which can greatly increase capacity. However, the difficulty of manganese oxide is that repeated charging and discharging can easily destroy the structure, and nanometers are also easy to condense into clusters.

The team dispersed the manganese oxide nanoparticles in the solution and mixed them with graphene to synthesize multiple layers of laminated composite materials. Both manganese oxide and graphene are negatively charged and usually repel each other. The team used chemically modified graphene as early as 2015 to make it positively charged, which solved the problem of rejection and achieved the maximum capacity and maximum life span of metal oxide negative electrode materials at that time.

This time, by combining the two substances from the molecular level, the high properties that are difficult to achieve for individual materials are obtained. In addition to being used for charging batteries, composite materials can also greatly improve the performance of energy storage and conversion systems such as supercapacitors and electrode catalysts.

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