The low initial Coulombic efficiency (ICE) and insufficient cycling lives of silicon (Si)‐based anodes seriously hinder their eventual introduction into next‐generation high‐energy‐density lithium–ion batteries (LIBs). Herein, an engineering prelithiation binder strategy based on polyacrylic acid (LixPAA) is proposed for representative SiOx anodes. The ICEs and cycling lives of SiOx anodes are significantly improved by precisely controlling the lithiation degree of PAA binder. The ICE of the high‐loading (3.0 mg cm−2) SiOx electrode increases by 10.9% when the Li0.75PAA binder replaces the PAA binder. Moreover, the working mechanism of the lithiation binder strategy to improve the electrochemical performances (especially for ICE) is systematically investigated, which is universally applied to other Si anodes such as Si nanoparticles and Si/graphite. This universal binder strategy and proposed working mechanism provide enlightenment on constructing high‐ICE, high‐energy‐density, and long‐life Si‐based anodes.
Conventional polymer binder in a lithium−sulfur (Li−S) battery, poly(vinylidene fluoride) (PVDF), suffers from insufficient ion conductivity, poor polysulfide-trapping ability, weak mechanical property, and requirement of organic solvents, which significantly encumber the industrial application of Li−S battery. Herein, a water-soluble binder with trifunctions, covalently cross-linked quaternary ammonium cationic starch (c-QACS), is developed to confront these issues. Similar to the poly(ethylene oxide) solid electrolytes, the c-QACS binder remarkably improves Li + ion transfer capacity. The abundant O actives endow the c-QACS binder with admirable lithium polysulfide-trapping capability to retard the shuttle effect. In addition, the formed 3D network effectively maintains the electrode integrity during cycling. Benefiting from the above merits, the sulfur cathode with the c-QACS binder demonstrates a performance improvement of 300 and 150% compared with sulfur cathode with PVDF and bulk QACS binder after 100 cycles at 0.2C.
A lithium−sulfur (Li−S) battery based on multielectron chemical reactions is considered as a next-generation energy-storage device because of its ultrahigh energy density. However, practical application of a Li−S battery is limited by the large volume changes, insufficient ion conductivity, and undesired shuttle effect of its sulfur cathode. To address these issues, an aqueous supramolecular binder with multifunctions is developed by cross-linking sericin protein (SP) and phytic acid (PA). The combination of SP and PA allows one to control the volume change of the sulfur cathode, benefit soluble polysulfides absorbing, and facilitate transportation of Li + . Attributed to the above merits, a Li−S battery with the SP− PA binder exhibits a remarkable cycle performance improvement of 200% and 120% after 100 cycles at 0.2 C compared with Li−S batteries with PVDF and SP binders. In particular, the SP−PA binder in the electrode displays admirable flameretardant performance due to formation of an isolating layer and the release of radicals.
Silicon oxide (SiO x ) has outstanding capacity and stable lithium-ion uptake/removal electrochemistry as a lithium-ion anode material; however, its practical massive commercialization is encumbered by unavoidable challenges, such as dynamic volume changes during cycling and inherently inferior ionic conductivities. Recent literature has offered a consensus that binders play a critical role in affecting the electrochemical performance of Si-based electrodes. Herein, we report an aqueous binder, γ-polyglutamic acid cross-linked by epichlorohydrin (PGA–ECH), that guarantees enhanced properties for SiO x anodes to implement long-term cycling stability. The abundant amide, carboxyl, and hydroxyl groups in the binder structure form strong interactions with the SiO x surface, which contribute strong interfacial adhesion. The robust covalent interactions and strong supramolecular interactions in the binder ensure mechanical strength and elasticity. Additionally, the interactions between lithium ions and oxygen (nitrogen) atoms of carboxylate (peptide) bonds, which serve as a Lewis base, facilitate the diffusion of lithium ions. A SiO x anode using this PGA–ECH binder exhibits an impressive initial discharge capacity of 1962 mA h g–1 and maintains a high capacity of 900 mA h g–1 after 500 cycles at 500 mA g–1. Meanwhile, the assembled SiO x ||LiNi0.6Co0.2MnO0.2 full cell shows a reversible capacity of 155 mA g–1 and displays 73% capacity retention after 100 cycles.
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