Improved cycling performance of nano-composite Li2Ni2(MoO4)3 as a lithium battery cathode material

We have recently reported our success in identifying a family of new polyanion cathode materials, namely Li2M′2(MoO4)3Li2M′2(MoO4)3 [M′ = Ni, Co and Mn] and synthesized these polyanion derivatives using soft-combustion based solution synthesize technique. It is known that the polyanion cathode materials reported hither to suffer invariably from intrinsic lattice electronic conductivities regardless of their structure. The new polyanion materials reported by us also suffer from low lattice electronic conductivity. Considering its lithium rich phase to be useful for battery application, we attempted to improvise the electronic conductivity of Li2Ni2(MoO4)3 by adding mesoporous (nano-sized) non-graphitized carbon black (NCB) particles as an additional conductive additive together with acetylene black and compared its electrochemical performance with the conventional composite electrode having acetylene black as a conductive additive. The test electrode fabricated with NCB as conductive additive has profound effect on the discharge properties by enhancing the grain–grain contact much more effectively and establishing much better intimacy between the electrode-active grains and thus improving the overall electronic conductivity of the composite electrode. As a result, we found that the conventional composite positive electrode yielded a first discharge capacity of 26 mAh g−1 between 4.9 and 2.0 V, whereas the nano-composite electrode yielded a discharge capacity of 86 mAh g−1 which is approximately a four-fold increase. It was also observed that NCB addition facilitated the extended cycling performance in terms of lithium insertion and structural stability retention of the host cathode material.