Weight Optimisation of Electric Vehicle through Hybrid Structural Batteries

Abstract

This paper contributes towards the research and development campaign on the weight reduction of electric vehicles through the technology of structural composite batteries. Batteries are the key component and an integral part of electric vehicles which constitutes a major proportion of the vehicle’s weight. Most of the electric vehicle manufacturers use lithium-ion batteries which are in recent years have gone through a major development. The use of lithium-ion batteries within a carbon reinforced composite structure of the car has given rise to the concept of structural batteries where both the mechanical strength of the structure and the chemistry of the battery to be optimized. Various aspects of design in the formulation of the structural batteries are reviewed including material selection with respect to its electrical and mechanical requirements. In this research work, properties of carbon fiber are utilised which provide mechanical strength to the vehicle whilst be an efficient electrode for the lithium-ion structural batteries. The impacts of lithiation on the strength of the structure and charge time for the batteries are explored. Significant results of weight reduction have been achieved by formulating the structural battery for the roof of a passenger car having a 30 kW-hr battery. At 0.7 mm of active electrode thickness is designed within the roof structure, the roof can store 5.9 kW-hr of energy with the reduction of 56.5 kg in overall weight of the vehicle. The battery pack of 255 kg gets completely replaced by the structural composite battery because of its magnificent specific charge capacity at the active electrode with the thickness of 3.5 mm.