阳离子插层钒酸盐,作为高性能钾金属电池(PMBs)的阴极,在K+插入和废弃时遭受结构崩溃。钒酸盐阴极中的外来阳离子可以缓解塌陷,然而,它们对内在阳离子的影响仍然是推测性的。在这里,稳定且无枝晶的PMB,由Na和K共插层钒酸盐(NKVO)阴极和液态NaK合金阳极组成,是presented。使用MXene前体轻松制备了一系列具有可调Na/K比的NKVO,其中Na+被证明在循环时被固定,作为结构支柱。由于Na+与K+相比具有更强的离子键和更低的费米能级,适度的Na+嵌入可以减少K+与溶剂化鞘的结合,有利于K+扩散动力学。因此,MXene衍生的Na+柱撑NKVO表现出显着改善的比容量,速率性能,和循环稳定性比不含Na+的对应物。此外,热处理碳纸,模仿中国宣纸的微观结构,允许高表面张力液体NaK合金容易粘附,使无枝晶的金属阳极。通过阐明外来插层阳离子的作用,这项研究可能导致更合理的设计稳定和高性能的电极材料。
Cation-intercalated vanadates, which have considerable promise as the cathode for high-performance potassium metal batteries (PMBs), suffer from structural collapse upon K+ insertion and desertion. Exotic cations in the vanadate cathode may ease the collapse, yet their effect on the intrinsic cation remains speculative. Herein, a stable and dendrite-free PMB, composed of a Na+ and K+ co-intercalated vanadate (NKVO) cathode and a liquid NaK alloy anode, is presented. A series of NKVO with tuneable Na/K ratios are facilely prepared using MXene precursors, in which Na+ is testified to be immobilized upon cycling, functioning as a structural pillar. Due to stronger ionic bonding and lower Fermi level of Na+ compared to K+ , moderate Na+ intercalation could reduce K+ binding to the solvation sheath and favor K+ diffusion kinetics. As a result, the MXene-derived Na+ -pillared NKVO exhibits markedly improved specific capacities, rate performance, and cycle stability than the Na+ -free counterpart. Moreover, thermally-treated carbon paper, which imitates the microscopic structure of Chinese Xuan paper, allows high surface tension liquid NaK alloy to adhere readily, enabling dendrite-free metal anodes. By clarifying the role of foreign intercalating cations, this study may lead to a more rational design of stable and high-performance electrode materials.