  The large volume change of the silicon (Si) during lithiation and
delithiation process has long been a problem impeding its application as one of
the most promising anode materials for LIBs. In this paper, we proposed a
conceptually new idea to address this problem simply by varying the thickness
of the electrode material film. The resulting thickness-gradient electrode
exhibits considerable enhancement in the electrochemical performances including
capacity, capacity retention, Coulombic efficiency, and rate capability in
comparison to the traditional counterparts with uniform thickness. Such
enhancement in the electrochemical performance can be attributed to the
lessening of the stress concentration on the interface between the electrode
film and the current collector upon the volume change of Si taking place in the
lithiation and delithiation process. To make the best use of this strategy,
optimal design of the gradient thickness is proposed based on the theory of
stress homogenization, followed by the experimental verification. The results
of this paper provide a facile, cost-effective, and scalable way for enhancing
the performance of Si-based anodes for LIBs. This strategy can be further
extended to the other anode materials suffering from the similar
lithiation-induced volume change problem.
