High energy-density, fast-chargeable lithium-ion batteries by mechanically interlocked polymers

Silicon anodes can play a key role in improving the energy density and fast-charging capability of lithium-ion batteries; however, their uncontrolled swelling remains a formidable hurdle in practice, particularly at a high electrode density, an essential parameter for high volumetric energy density. To address this challenge, we report here a polymeric poly(acrylic acid) binder with mechanically interlocked crosslinks to realize a topologically entangled polymer network. This binder system effectively dissipates the stress resulting from electrode calendering and repeated cycling via various mechanical motions at the mechanically interlocked crosslinks, which offer spatially homogeneous mechanical strength and elasticity. This design markedly improves the cycle life and fast-charging capability of silicon-graphite electrodes over those using conventional binders at high electrode densities, highlighting the usefulness of a mechanically interlocked polymer network in distributing the stress of high-capacity battery electrodes during their fabrication and operation.