High‐Efficiency Cathode Sodium Compensation for Sodium‐Ion Batteries

Abstract

Sodium‐ion batteries have gained much attention for their potential application in large‐scale stationary energy storage due to the low cost and abundant sodium sources in the earth. However, the electrochemical performance of sodium‐ion full cells (SIFCs) suffers severely from the irreversible consumption of sodium ions of cathode during the solid electrolyte interphase (SEI) formation of hard carbon anode. Here, a high‐efficiency cathode sodiation compensation reagent, sodium oxalate (Na2C2O4), which possesses both a high theoretical capacity of 400 mA h g−1 and a capacity utilization as high as 99%, is proposed. The implementation of Na2C2O4 as sacrificial sodium species is successfully realized by decreasing its oxidation potential from 4.41 to 3.97 V through tuning conductive additives with different physicochemical features, and the corresponding mechanism of oxidation potential manipulation is analyzed. Electrochemical results show that in the full cell based on a hard carbon anode and a P2‐Na2/3Ni1/3Mn1/3Ti1/3O2 cathode with Na2C2O4 as a sodium reservoir to compensate for sodium loss during SEI formation, the capacity retention is increased from 63% to 85% after 200 cycles and the energy density is improved from 129.2 to 172.6 W h kg−1. This work can provide a new avenue for accelerating the development of SIFCs.

Pillar-beam structures prevent layered cathode materials from destructive phase transitions

“…It is worth noting that although we have suppressed the P2-O2 phase transition to achieve high capacity and long cycle life, the relatively low sodium content in the P2 cathode materials in general could still be a limiting factor for their commercial applications in sodium-ion batteries. Sodium supplementation through additives, pre-sodiated and metallic negative electrodes 50 , 51 can be solutions to this issue.…”

Ultra-Low-Dose Pre-Metallation Strategy Served for Commercial Metal-Ion Capacitors

“…Nevertheless, the high decomposition potential of Na 2 C 2 O 4 seriously hinders the irreversible output capacity, accordingly causing the dosage-abuse issue. Moreover, exorbitant activation potential may lead to the break-down of electrolyte on the cathode side and potential unsafe reactions, resulting in poor electrochemical performance, thereby impairing the practical application of SICs [ 34 , 35 ].…”

High-performance all-solid-state electrolyte for sodium batteries enabled by the interaction between the anion in salt and Na3SbS4

“…[1][2][3][4][5] The reported sodium batteries are mainly based on liquid electrolytes with ammable organic solvents, such as esters and ethers, which inevitably bring about leakage, volatilization, and subsequent safety issues. 6,7 In contrast, all-solidstate electrolytes show the advantages of no leakage, good stability, and high safety. [8][9][10][11][12][13][14] The reported all-solid-state electrolytes for sodium batteries can be roughly categorized into two types, organic polymer and inorganic electrolytes.…”