Engineering CoP Alloy Foil to a Well‐Designed Integrated Electrode Toward High‐Performance Electrochemical Energy Storage

Nanostructured integrated electrodes with binder-free design show great potential to solve the ever-growing problems faced by currently commercial lithium-ion batteries such as insufficient power and energy densities. However, there are still many challenging problems limiting practical application of this emerging technology, in particular complex manufacturing process, high fabrication cost, and low loading mass of active material. Different from existing fabrication strategies, here using a CoP alloy foil as a precursor a simple neutral salt solution-mediated electrochemical dealloying method to well address the above issues is demonstrated. The resultant freestanding mesoporous np-Co(OH)x /Co2 P product possesses not only active compositions of high specific capacity and large electrode packing density (>3.0 g cm-3 ) to meet practical capacity requirements, high-conductivity and well-developed nanoporous framework to achieve simultaneously fast ion and electron transfer, but also interconnected ligaments and suitable free space to ensure strong structural stability. Its comprehensively excellent electrochemical energy storage (EES) performances in both lithium/sodium-ion batteries and lithium-ion capacitors can further illustrate the effectiveness of the integrated electrode preparation strategy, such as remarkable reversible specific capacities/capacitances, dominated pseudo-capacitive EES mechanism, and ultra-long cycling life. This study provides new insights into preparation and design of high-performance integrated electrodes for practical applications.