Anchoring ultrafine CoP and CoSb nanoparticles into rich N-doped carbon nanofibers for efficient potassium storage

Abstract

Transition-metal compounds have received extensive attention from researchers due to their high reversible capacity and suitable voltage platform as potassium-ion battery anodes. However, these materials commonly feature a poor conductivity and a large volume expansion, thus leading to underdeveloped rate capability and cyclic stability. Herein, we successfully encapsulated ultrafine CoP and CoSb nanoparticles into rich N-doped carbon nanofibers (NCFs) via electrospinning, carbonization, and phosphorization (antimonization). The N-doped carbon fiber prevents the aggregation of nanoparticles, buffers the volume expansion of CoP and CoSb during charging and discharging, and improves the conductivity of the composite material. As a result, the CoP/NCF anode exhibits excellent potassium-ion storage performance, including an outstanding reversible capacity of 335 mA h g⁻¹, a decent capacity retention of 79.3% after 1000 cycles at 1 A g⁻¹ and a superior rate capability of 148 mA h g⁻¹ at 5 A g⁻¹, superior to most of the reported transition-metalbased potassium-ion battery anode materials.

摘要

作为钾离子电池负极, 过渡金属化合物由于其高可逆容量和合适的电压平台而受到研究人员的广泛关注. 然而, 这些材料通常具有较差的导电性和超过80%的体积膨胀. 这些缺点往往会对电池的倍率性能和循环稳定性产生不利影响. 在本文中, 我们通过静电纺丝、碳化和磷化(锑化)成功地将超细CoP和CoSb纳米颗粒封装到富氮掺杂的碳纳米纤维中. 氮掺杂的碳纳米纤维有效防止了纳米颗粒聚集, 缓冲了充放电过程中CoP和CoSb的体积膨胀, 并提高了材料的导电性. 因此, CoP/氮掺杂的碳纳米纤维(CoP/NCF)负极表现出优异的钾离子存储性能, 包括335 mA h g ⁻¹ 的可逆容量、长循环性能(在1 A g⁻¹ 下经1000次循环仍能保持79.3%的初始可逆容量), 以及在5 A g⁻¹ 下148mAh g⁻¹的优异倍率性能, 超过了大多数已报道的过渡金属化合物基钾离子电池负极材料.