Low-cost p-benzoquinone-formaldehyde polymer/reduced graphene oxide composite films as a cathode material for rechargeable lithium-ion batteries

The high theoretical capacity of p-benzoquinone makes it a promising cathode for lithium-ion batteries, but its high solubility in organic electrolytes leads to low cycling stability. Although the dissolution problem can be solved by grafting p-benzoquinone groups into polymers, polymerized cathode materials suffer from low electrical conductivity and reduced specific capacity. In this article, a p-benzoquinone-formaldehyde polymer is designed and synthesized, composited with reduced graphene oxide, forming p-benzoquinone-formaldehyde polymer/reduced graphene oxide composite films. The p-benzoquinone-formaldehyde polymer has a high theoretical capacity, while reduced graphene oxide increases the electrical conductivity of composite films and inhibits the dissolution of the p-benzoquinone-formaldehyde polymer through adsorption. The composite films exhibit high practical capacity at large current densities with excellent cycling stability. At a current density of 500 mA g(-1), the initial energy density is 329.5 W h kg(-1). After 1000 cycles at a current density of 2500 mA g(-1), the capacity retention is 99.2%. The reversible capacity reaches 225 mA h g(-1) at a current density up to 10 000 mA g(-1). Besides, the inexpensive monomers and facile polymerization process lead to quite low cost for composite films. The high performance and low cost of the composite films make them a new promising cathode material for high power lithium-ion batteries.