Abstract
Silicon-based materials are promising anodes for next-generation lithium-ion batteries, owing to their high specific capacities. However, the huge volume expansion and shrinkage during cycling result in severe displacement of silicon particles and structural collapse of electrodes. Here we report the use of a supremely elastic gel polymer electrolyte to address this problem and realize long-term stable cycling of silicon monoxide anodes. The high elasticity of the gel polymer electrolyte is attributed to the use of a unique copolymer consisting of a soft ether domain and a hard cyclic ring domain. Consequently, the displacement of silicon monoxide particles and volume expansion of the electrode were effectively reduced, and the damage caused by electrode cracking is alleviated. A SiO|LiNi0.5Co0.2Mn0.3O2 cell shows 70.0% capacity retention in 350 cycles with a commercial-level reversible capacity of 3.0 mAh cm−2 and an average Coulombic efficiency of 99.9%.
Highlights
Silicon-based materials are promising anodes for next-generation lithium-ion batteries, owing to their high specific capacities
We here report a strategy using a supremely elastic gel polymer electrolyte (GPE), serving as an intra-electrode cushion to reduce the electrode expansion during lithiation and to facilitate the electrode to recover its structure during delithiation
This unique soft-hard combined structure provides the copolymer with supreme elasticity and helps maintain the electrode integrity with cycling
Summary
Silicon-based materials are promising anodes for next-generation lithium-ion batteries, owing to their high specific capacities. The huge volume changes of Si-based materials result in remarkable displacement of material particles and thickness increase of electrodes in the lithiation (Fig. 1a) This structural damage is not retrievable in the delithiation process, causing the loss of electrode integrity, unstable solid-electrolyte interphase (SEI) layers, and electrode peeling-off from current collectors[17,18,19]. In addition to the repair of electrode structure after cracking occurs, strategies to intrinsically alleviating the displacement of material particles and electrode cracking are highly needed To this end, we here report a strategy using a supremely elastic gel polymer electrolyte (GPE), serving as an intra-electrode cushion to reduce the electrode expansion during lithiation and to facilitate the electrode to recover its structure during delithiation. When paring with a LiNi0.5Co0.2Mn0.3O2 (NCM) cathode, the cell displays capacity retention of 70.0% in 350 cycles with a reversible capacity of 3.0 mAh cm−2 and an average Coulombic efficiency of 99.9%
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