Carbon-Nanotubes Li-ion Battery Based Electrodes with Enhanced Thermal Conductivity

PAULA CECILIA DOS SANTOS CLARO; BONIL KOO; GOLI PRADYUMNA; ANIRUDHA SUMANT; TIJANA RAJH; CHRISTOPHER JOHNSON; ALEXANDER BALANDIN; SOMA CHATTOPADHYAY; TOMOHIRO SHIBATA; VITALI B. PRAKAPENKA; LISANDRO J. GIOVANETTI; LEANDRO ANDRINI; FÉLIX G. REQUEJO; ELENA V. SHEVCHENKO

Chicago

Conferencia; New Diamond and Nano Carbons Conference (NDNC 2014); 2014

Owing to their superior power­density Li­ion batteries are used in a wide variety of applications. One of the main drawbacks with this and similar types of batteries is overheating and related safety concerns. The heat is generated during the operation of any battery as current flows through its internal resistance whether it is being charged or discharged. In the case of discharging, the temperature rise is limited by the energy available. However, no such limit exists in the charging cycle when energy can be pumped even after full charging of the battery. In addition to Ohmic heating, chemical reactions that take place during charging and discharging in Li­ion batteries can also contribute to overheating. If this issue is not properly address, thermal runaway may cause a catastrophic destruction of the battery. In addition to that, efficient heat removal from the battery allows achieving higher currents, resulting in faster charging/discharging rates, which are important both of stationary and transportation application of batteries. We present the study of electrochemical and thermal properties of a set of different multiwall carbon nanotubes (CNT) Li­ion battery based electrodes. The electrode material is prepared by a scalable and inexpensive filtration method, where we utilize CNT as a matrix for encapsulation of electrochemically active cathode materials. For the present work we synthesized CNT­samples with varying layered structure, using hollow γ­Fe2O3 nanoparticles (NPs) and Li[Ni1/3Co1/3Mn1/3]O2 microparticles. These CNTs­based electrodes have significantly higher thermal conductivities as compared to conventional carbon black based electrodes. We show that cross­sectional and in­plane thermal conductivities of the hollow γ­Fe2O3 NPs on CNTs sandwiched between two layers of CNTs, that was previously found to be efficient cathode material, are 3.0 W/mK and 49.54 W/mK, respectively, without any engineered controls of heat removal. These values are about one and two orders higher than those observed on carbon black based electrodes obtained via conventional approach. Moreover, the proposed filtration method can be applied towards design of electrodes with high thermal conductivities using commercial electrode active materials. In addition to the results described above, we present a chemical approach to introduce molybdenum into hollow iron oxide NPs. Mo­doped iron oxide NPs, which contain a significantly large amount of cation vacancies in both tetrahedral and octahedral sites, were utilized to enhance Li­ion battery capacity at high voltage. Thus Mo­doped hollow NPs serve as hosts for lithium ions at high voltage range (4.5­1.5 V) with additional 23% reversible capacity comparing to non­doped iron oxide NPs and enhanced working voltage by 200 mV. We investigated oxidation state and local distribution of Fe and Mo in Mo­doped iron oxide NPs during lithium ion intercalation/deintercalation using synchrotron X­ray studies.