Improved Capacity Retention of Metal Oxide Anodes in Li‐Ion Batteries: Increasing Intraparticle Electronic Conductivity through Na Inclusion in Mn₃O₄

Abstract

In this work, we significantly improve the cyclability of Mn3O4 anodes in Li‐ion batteries by enhancing its intraparticle electronic conductivity by doping with Na. Na was selected because, unlike typical transition‐metal dopants, it is non‐surface redox active in the potential window where the metal oxide conversion reaction occurs, and hence is more electrochemically stable during charge/discharge cycling. This work presents the first time that Na has been used as a dopant in metal oxide anodes, and the result is excellent capacity retention and rate capability. More specifically, Na was added to Mn3O4 (to achieve a Mn/Na ratio of ca. 9 : 1), impregnated onto a carbon nanotube matrix. The concentration of Na considering the entire composition of the anode material was 0.5 at %. These electrodes were able to achieve a capacity of approximately 750 mAh/g at a 1C rate, and retain over 99 % of that capacity over 500 cycles. They were also able to provide nearly twice the theoretical capacity of conventional graphite anodes under high rate discharge (609 mAh/g @ 5C), as well as achieve a higher capacity at 10C (ca. 350 mAh/g) than conventional graphite electrodes can at 1C.

Low-Temperature Lithium Plating/Corrosion Hazard in Lithium-Ion Batteries: Electrode Rippling, Variable States of Charge, and Thermal and Nonthermal Runaway

“…However, as different applications adopt NMC/graphite chemistries, the battery limits and degradation mechanisms under harsh conditions require better elucidation. Extreme conditions and discrepancies in Li-ion battery operating conditions (i.e., oscillations in temperatures, current, and depth-of-discharge) − and chemistry (i.e., additive engineering, fluorination, electrolyte, and anodes/cathodes) − has led to unpredictable variations in the onset for catastrophic cell failure (i.e., rapid performance degradation, abrupt cell death, and thermal runaway). − In particular, electrified transportation (e.g., electric cars, electric trucks, and aircraft) − are on the precipice of extreme operating conditions, which include repetitive fast-charge/fast-discharge in a matter of seconds (i.e., acceleration and regenerative brakes) − and possible exposure to extreme temperatures on Earth ranging from −29 °C (e.g., mountainous regions and troposphere for commercial airplanes) to +52 °C (e.g., desert regions and hotter areas) or abusive cold-mission space temperatures down to −20 °C to −40 °C with thermal regulators (e.g., exploration rovers and spacecraft) . In addition, thermal expansion and contraction due to temperature oscillations can lead to thermal shock and mechanical failures, including active material delamination and current collector cracking.…”

Using nanoconfinement to inhibit the degradation pathways of conversion-metal oxide anodes for highly stable fast-charging Li-ion batteries

“…7,8 Therefore, new LIB anode materials are needed that are safer (no Li plating during fast charging), have higher capacities (>600 mA h g À1 ), and are durable (>1000 deep cycles). [9][10][11] One pathway for materials development, to achieve high rate charging at lower overpotentials (reducing the driving force for Li-plating), is to create nano-sized electroactive materials. Small particle sizes allow for enhanced reaction kinetics and rapid diffusion.…”

“…Third, there can be continued growth of the solid electrolyte interphase (SEI) due to physical changes in the electrode during charge/discharge, [35][36][37][38][39] which can reduce the electrode capacity during cycling through both increased irreversible capacity loss as well as particle detachment and metal trapping within the SEI. [40][41][42][43] Finally, through reaction either with excess electrolyte or the SEI, MOs undergo a side reaction that forces them to higher oxidation states during their lifetimea reaction that lowers their achievable coulombic efficiency (but not their achievable capacity since the reaction does not consume Li) 9 . In combination, these four degradation mechanisms have oen signicantly limited the performance and lifetime of MO-based anode materials and have led to their exclusion from cells of commercial interest.…”

Novel Hoberman Sphere Design for Interlaced Mn3O4@CNT Architecture with Atomic Layer Deposition-Coated TiO2 Overlayer as Advanced Anodes in Li-Ion Battery

“…Lithium ion batteries (LIBs) is the most popular energy storage system for portable electronic devices and electric vehicles in the modern society . Even though tremendous research efforts have been devoted, LIBs still cannot fully meet the evergrowing demand toward higher energy density. − The development of advanced anode materials for LIBs is urgently required because of the relatively low theoretical capacity of commercial graphite. − The conversion-type transition metal oxides with ultrahigh theoretical capacity and environmental friendliness are recognized as the most promising anode candidates for the next-generation LIBs. − Mn 3 O 4 is environmentally friendly, possesses a high theoretical specific capacity of 937 mAh g –1 , a low operating voltage, − and an ultrafast lithiation/delithiation kinetics compared to its manganese oxide counterparts due to the more easily exposed high energy facets, all of which make it highly preferred in the applications of high-power density systems . However, the huge volume changes during cycling will affect the integrity and stability of the Mn 3 O 4 , resulting in particle aggravation, severe active material degradation, and poor cycle life, which will seriously hinder the large-scale practical application of the Mn 3 O 4 anode. , …”