The electrochemical behavior of sulfur-based batteries is intrinsically governed by polysulfide species. Here, we compare the substitutions of selenium and tellurium into polysulfide chains and demonstrate their beneficial impact on the chemistry of lithium–sulfur batteries. While selenium-substituted polysulfides enhance cathode utilization by effectively catalyzing the sulfur/Li₂S conversion reactions due to the preferential formation of radical intermediates, tellurium-substituted polysulfides improve lithium cycling efficiency by reducing into a passivating interfacial layer on the lithium surface with low Li⁺-ion diffusion barriers. This unconventional strategy based on “molecular engineering” of polysulfides and exploiting the intrinsic polysulfide shuttle effect is validated by a ten-fold improvement in the cycle life of lean-electrolyte “anode-free” pouch cells. Assembled with no free lithium metal at the anode, the anode-free configuration maximizes the energy density, mitigates the challenges of handling thin lithium foils, and eliminates self-discharge upon cell assembly. The insights generated into the differences between selenium and tellurium chemistries can be applied to benefit a broad range of metal–chalcogen batteries as well as chalcogenide solid electrolytes.

中文翻译：

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可充电电池多硫化物中原位硫属元素取代的影响

硫基电池的电化学行为本质上受多硫化物种类的控制。在这里，我们比较了硒和碲对多硫化物链的替代，并证明了它们对锂硫电池化学的有益影响。由于优先形成自由基中间体，硒取代的多硫化物通过有效催化硫/Li ₂ S转化反应来提高阴极利用率，而碲取代的多硫化物通过在锂表面还原成具有低Li的钝化界面层来提高锂循环效率⁺-离子扩散屏障。这种基于多硫化物“分子工程”并利用内在多硫化物穿梭效应的非常规策略得到了验证，将贫电解质“无阳极”软包电池的循环寿命提高了十倍。在阳极没有游离锂金属的情况下组装，无阳极配置最大限度地提高了能量密度，减轻了处理薄锂箔的挑战，并消除了电池组装时的自放电。对硒和碲化学之间差异的见解可用于广泛的金属硫属元素电池以及硫属元素化物固体电解质。