Ultrafast Charge and Long Life of High-Voltage Cathodes for Dual-Ion Batteries via a Bifunctional Interphase Nanolayer on Graphite Particles,Small

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Ultrafast Charge and Long Life of High-Voltage Cathodes for Dual-Ion Batteries via a Bifunctional Interphase Nanolayer on Graphite Particles
Small ( IF 13.0 ) Pub Date : 2023-01-01 , DOI: 10.1002/smll.202206360
Kejia Zhang ₁ , Decheng Li ₁ , Jie Shao ₂ , Yu Jiang ₁ , Linze Lv ₁ , Qiang Shi ₃ , Qunting Qu _{1,

3} , Honghe Zheng _{1,

3}

Affiliation

Dual-ion batteries (DIBs) with Co/Ni-free cathodes especially graphite cathodes are very attractive energy storage systems in the long run because of the cost effectiveness and sustainability. However, graphite cathodes severely suffer from poor structural stability during anions storage at high potentials owing to the oxidative decomposition of electrolytes and volume expansion. This work proposes an artificial cathode/electrolyte interphase (CEI) strategy by implanting polyphosphoric acid (PPA) nanofilms tightly on natural graphite (NG) particles via interfacial hydrogen bonding. The electrochemical results show that the PPA-modified graphite cathodes possess enhanced charge–discharge reversibility, accelerated electrode reaction kinetic, decreased resistance, decelerated self-discharge, and prolonged cycling life. Through post-analyses on the cycled graphite cathodes, the improved performance is mainly attributed to the PPA-based CEI, which effectively mitigates the electrolyte decomposition and protects the graphitic structure. More interestingly, the hydrogen bonding interactions between poly(vinyldifluoride) (PVDF) binder and PPA as validated through density functional theory calculations and practical experiments can increase the contact sites of PVDF chains on NG@PPA particles. Meanwhile, the cross-linking effect of PPA can enhance the mechanical strength of PVDF, thus the long life of NG@PPA cathode is also correlated with the improved mechanical stability of the entire electrode.

中文翻译：

通过石墨颗粒上的双功能界面纳米层实现双离子电池高压阴极的超快充电和长寿命

由于成本效益和可持续性，从长远来看，具有无钴/镍阴极（尤其是石墨阴极）的双离子电池 (DIB) 是非常有吸引力的储能系统。然而，由于电解质的氧化分解和体积膨胀，石墨正极在高电位下储存阴离子时结构稳定性差。这项工作提出了一种人工阴极/电解质界面 (CEI) 策略，通过界面氢键将多聚磷酸 (PPA) 纳米膜紧密植入天然石墨 (NG) 颗粒上。电化学结果表明，PPA 改性石墨正极具有增强的充放电可逆性、加速的电极反应动力学、降低的电阻、减慢的自放电和延长的循环寿命。通过对循环石墨正极的后分析，改进的性能主要归功于基于 PPA 的 CEI，它有效地减轻了电解质分解并保护了石墨结构。更有趣的是，通过密度泛函理论计算和实际实验验证的聚二氟乙烯（PVDF）粘合剂和 PPA 之间的氢键相互作用可以增加 NG@PPA 颗粒上 PVDF 链的接触位点。同时，PPA的交联作用可以增强PVDF的机械强度，因此NG@PPA正极的长寿命也与整个电极机械稳定性的提高有关。有效减缓电解液分解，保护石墨结构。更有趣的是，通过密度泛函理论计算和实际实验验证的聚二氟乙烯（PVDF）粘合剂和 PPA 之间的氢键相互作用可以增加 NG@PPA 颗粒上 PVDF 链的接触位点。同时，PPA的交联作用可以增强PVDF的机械强度，因此NG@PPA正极的长寿命也与整个电极机械稳定性的提高有关。有效减缓电解液分解，保护石墨结构。更有趣的是，通过密度泛函理论计算和实际实验验证的聚二氟乙烯（PVDF）粘合剂和 PPA 之间的氢键相互作用可以增加 NG@PPA 颗粒上 PVDF 链的接触位点。同时，PPA的交联作用可以增强PVDF的机械强度，因此NG@PPA正极的长寿命也与整个电极机械稳定性的提高有关。

更新日期：2023-01-01

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