A Reanalysis of the Diverse Sodium Species in Carbon Anodes for Sodium Ion Batteries: A Thermodynamic View

Abstract

Sodium ion batteries (SIBs) have been extensively investigated as a promising alternative for lithium ion batteries (LIBs) owing to the readily available character of sodium, lower costs of battery systems, as well as a similar working mechanism to LIBs. However, this view turns out to be oversimplified; countless reviews especially in the last years contradict each other, and it is still a challenging task to design highly performing electrode materials for SIBs. Due to the larger radius of Na+, its lower covalent character, and the resulting changes in intercalation chemistry, sodium is far from being only the bigger relative of lithium, and the difference leads to altered loading curves, and the occurrence of a multiplicity of binding sites. An in‐depth holistic understanding of the sodium storage mechanisms is needed to resolve the controversial discussions in the research community, ideally starting with unquestionable thermodynamic points. Here, taking a tutorial perspective, first the recent discussions on the storage mechanism of sodium in carbons are reviewed from an unorthodox viewpoint, namely addressing sodium uptake as a multifaceted adsorption process with an added electrochemical binding potential. This model is based on literature data. Afterward, challenges and perspectives revealed by such a model are discussed.

Microcrystalline Hybridization Enhanced Coal‐Based Carbon Anode for Advanced Sodium‐Ion Batteries

“…In contrast, sodium-ion batteries (SIBs) are considered as a promising candidate for grid energy storage based on their satisfactory electrochemical performance, large reserves, and low cost. [5][6][7][8] Nevertheless, compared with Li ion (0.76 Å), the much larger ion radius of Na ion (1.02 Å) makes it difficult to find appropriate electrode materials for SIBs. [9,10] For example, graphite, a commercially successful LIBs anode, has poor Na-storage performance with a reversible capacity of 35 mAh g −1 due to difficult intercalation of larger Na + between the graphite interlayer as well as the graphite intercalation compound of Na is thermodynamically more unstable than those of other alkalis.…”

A robust solvothermal-driven solid-to-solid transition route from micron SnC2O4 to tartaric acid-capped nano-SnO2 anchored on graphene for superior lithium and sodium storage

“…9–11 However, the larger diameter of Na + (2.04 Å) than that of Li + (1.52 Å) leads to the sluggish reaction kinetics of Na + with an extremely low insertion capability in graphite. 12–23 Overall, the development of high-performance and commercializable anodes has become a top priority in the development of LIBs and SIBs. 16,24,25…”

“…[9][10][11] However, the larger diameter of Na + (2.04 Å) than that of Li + (1.52 Å) leads to the sluggish reaction kinetics of Na + with an extremely low insertion capability in graphite. [12][13][14][15][16][17][18][19][20][21][22][23] Overall, the development of high-performance and commercializable anodes has become a top priority in the development of LIBs and SIBs. 16,24,25 Tin dioxide (SnO 2 ) is considered as one of the most encouraging anodes for LIBs and SIBs due to its ultrahigh mass and volume specic TCs (i.e., 1494 mA h g −1 and 10 383 mA h cm −3 for LIBs and 1378 mA h g −1 and 9577 mA h cm −3 for SIBs).…”

Boosting Surface‐Dominated Sodium Storage of Carbon Anode Enabled by Coupling Graphene Nanodomains, Nitrogen‐Doping, and Nanoarchitecture Engineering

“…[ 2 ] Graphite, as the most common anode material in lithium‐ion batteries, delivers an extremely low capacity in SIBs because the insufficient interlayer spacing cannot form thermodynamically stable sodium intercalation compounds. [ 3 ] In contrast to graphite, amorphous carbon has been demonstrated as the most promising anode material due to its abundant active sites and larger interlayer spacing. [ 4 ] Extensive works have pointed out that amorphous carbon materials achieve a surface‐induced Na‐adsorption mechanism at high potential and a Na‐intercalation mechanism at low potential, which are assigned to the capacitive controlled process and the diffusion‐controlled process, respectively.…”