Due to their superior energy density, rate capabilities and wide range of applications in portable electronics, medical implants, and electric cars etc., rechargeable Li-ion batteries are favorable candidates for electrochemical energy storage. Despite many advantages, use of graphite anodes (specific capacity of 372 mAh/g) limits their power density and specific capacity, which is essential for a number of commercial applications including rechargeable electric vehicles. Lithiation of graphite anodes at lower potentials (&lt;0.3 V vs Li<sup>+</sup>/Li) also results in lithium dendrite growth and thereby challenging the overall safety of Li-ion batteries. Consequently, extensive research has been dedicated for the development of alternative high-capacity transition metal or metal oxide anode materials. Oxides of cobalt and manganese are attractive anode material for Li-ion batteries due to their high specific capacities. However, the implementation of these transition metal oxides is problematical due to poor electronic conductivity and cycling performance. Their poor cycling stability and rate performance is often associated with large volume change during charge-discharge process. Loss of electrical contacts and formation of electrochemically inactive clusters are other reasons for rapid capacity fading on prolonged cycling.<br/>We addressed the above mentioned issues by anchoring Co and Mn nanoparticles on porous carbon nanosheets and microcompartments. In this method, a homogeneous mixture of Co, Mn, and carbon precursors are heated under inert atmosphere (400-800 C). The carbon formed at high temperature act as reducing agent and convert metal salts to the corresponding nanoparticles. This process results in the homogeneous distribution of metal nanoparticles and their anchoring on the carbon support. Various spectroscopic and microscopic techniques are employed for the structural investigation of the metal-carbon hybrid. AFM studies proved that metal nanoparticles are physically bonded to the carbon substrate. The metal nanoparticle carbon hybrid electrodes exhibited excellent specific capacities, rate performance and cycling stabilities. We attributed the superior electrochemical performance to the physical bond between metal nanoparticles and carbon support, which improve electronic conductivity, accomodate volume changes during lithiation, avoid loss of electrical contacts, and formation of electrochemically inactive clusters.

Transition metal nanoparticles anchored on carbon anodes for advanced Li-ion storage

249th National Meeting (2015)

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