New material to give lithium-metal batteries ultra-long cycle life
In today's rapidly changing energy storage technology, lithium metal batteries are regarded as an important direction for future battery technology due to their high energy density and potential safety enhancement, in which the optimisation of solid-state electrolyte performance is particularly critical. Although traditional polymer electrolytes have the advantages of good interfacial contact and high potential for industrial production, they face challenges such as insufficient mechanical properties, low lithium ion (Li+) transport efficiency, and poor electrode or electrolyte interfacial stability in practical applications. These problems seriously limit the performance and lifetime of lithium metal batteries.
Schematic design of acylamino functionalised materials
Through the introduction of abundant acylamino sites, a unique hierarchical supramolecular network has been constructed, which cleverly combines permanent chemical cross-linking and reversible hydrogen bonding, enabling the polymer electrolyte to maintain a high degree of mechanical strength while possessing excellent flexibility. More importantly, the introduction of acylamino sites provides a fast and reversible transport channel for lithium ions, which significantly improves the ionic conductivity of the electrolyte. In addition, the pre-desolvation effect of the entire polymer matrix further promotes the transport efficiency of lithium ions, resulting in more rapid and uniform migration through the electrolyte.
In addition to excellent transport properties, this new polymer electrolyte forms a stable interfacial layer on the electrode surface, effectively preventing the formation of lithium dendrites and interfacial side reactions. Lithium dendrites are a common problem in lithium-metal batteries, where they not only lead to short-circuiting, but also accelerate the aging process of the battery. Therefore, this double-enhanced interfacial stability is crucial for improving the safety and cycle life of the battery.
Experimental results show that lithium-metal batteries with this new electrolyte exhibit impressive durability in cycle tests. Under complete charging and discharging, the capacity retention rate of the battery with lithium iron phosphate positive electrode paired with lithium metal negative electrode remained as high as 96.5 per cent after 850 cycles, while the battery with lithium cobalt oxide positive electrode maintained 96.8 per cent of its capacity after 300 cycles.
It is understood that this new achievement is a major innovation in the design of solid-state electrolyte, proving its great potential in practical applications, providing new ideas for solving the many challenges faced by lithium metal batteries, and laying a solid theoretical foundation and material basis for the future development of higher performance, longer life solid-state batteries.