Novel Composite Anodes Consisting of Lithium Transition-Metal Nitrides and Transition Metal Oxides for Rechargeable Li-Ion Batteries

Lithium transition-metal nitrides are promising anode candidates for Li-ion batteries. However, lithium must be extracted from the nitrides in an initial anodic oxidation, indicating these compounds cannot directly combine with the current cathodes to constitute cells. This deterrent can be overcome by introducing a certain amount of Co 3 O 4 , which shows large capacities and relatively high oxidation/reduction potentials, into the electrodes containing the above nitrides. A thermodynamically spontaneous reaction between these two active hosts results in a delithiated state of lithium metal nitrides. Under cycling within 1.4-0 V vs Li/Li + Co 3 O 4 is relatively inert to lithium and the nitrides become electrochemically active. The composite electrodes show high first-cycle efficiency of 100%, large capacities of 500 mAh g - 1 , and excellent cyclability. Furthermore, research revealed that the composite electrodes demonstrated high cycling stability operating with polyethylene oxide (PEO) electrolytes at the elevated temperature. The reaction heating of the composite electrode under high Li utilization with PEO electrolytes via differential scanning calorimetry measurement was found to be extremely low compared with those of the lithium metal and the Li-alloy-based systems. suggesting that the composite electrodes could be promising anode candidates for all-solid-state PEO Li-ion batteries in terms of capacity, first-cycle charge efficiency, and thermal reliance.

锂过渡金属氮化物是锂离子电池有前景的负极候选材料。然而，在初始阳极氧化过程中必须从氮化物中提取锂，这表明这些化合物不能直接与当前的正极结合构成电池。通过在含有上述氮化物的电极中引入一定量的四氧化三钴（Co₃O₄）可以克服这一障碍，四氧化三钴具有高容量和相对较高的氧化/还原电位。这两种活性主体之间的热力学自发反应导致锂金属氮化物处于脱锂状态。在相对于Li/Li⁺为1.4 - 0 V的电压范围内循环时，四氧化三钴对锂相对惰性，而氮化物变得具有电化学活性。复合电极显示出100%的首次循环高库仑效率、500 mAh g⁻¹的高容量以及优异的循环性能。此外，研究表明，复合电极在高温下与聚环氧乙烷（PEO）电解质一起使用时表现出高循环稳定性。通过差示扫描量热法测量发现，在高锂利用率下复合电极与聚环氧乙烷电解质的反应热与锂金属和锂合金基体系相比极低，这表明就容量、首次循环充电效率和热可靠性而言，复合电极可能是全固态聚环氧乙烷锂离子电池有前景的负极候选材料。