Performance Evaluation and Analysis of DTD Derivatives in Sodium-Ion Battery Systems
I. Performance Summary and Analysis
The DTD derivative additives (ARC-S20, ARC-S24, ARC-S28) developed by Rolechem exhibit differentiated performance in sodium-ion battery systems (NFPP/HC 1Ah pouch cells). Their core characteristics can be summarized from four dimensions: film-forming mechanism, basic performance, rate capability, and high-temperature/high-voltage stability.
II. Evaluation Conditions
Experimental Scheme:
Cell Type: 1Ah pouch cell
Chemistry System: NFPP / Hard Carbon (HC)
Voltage Window: 1.5 V – 3.6 V
Electrolyte Baseline (Common Components): PC : EMC : DEC = 6 : 7 : 7 , 0.7 M NaPF6 + 0.3 M NaFSI, with FEC + NaTFOP + NaDFP additives
Base Group: Common Components + DTD
ARC-S20: Common Components + S20
ARC-S24: Common Components + S24
ARC-S28: Common Components + S28
III. Experimental Results
1. Capacity and Film-Forming Mechanism: Significant advantage of early film formation, laying the foundation for performance
01 Film-Forming Potential:
The film-forming potentials of ARC-S20, ARC-S24, and ARC-S28 are all around 1.2 V, significantly lower than that of DTD (around 2.2 V). This enables them to preferentially form a solid electrolyte interphase (SEI) film during the initial charge-discharge cycle of the battery.
02 Film-Forming Efficiency:
Compared with the other three additives (ARC-S20, ARC-S24, DTD), ARC-S28 shifts the subsequent reduction peak to lower potentials, indicating that its film-forming reaction is easier to trigger. It may form a denser and more uniform SEI film, thereby reducing continuous electrolyte decomposition and ensuring cycling stability.
Analysis: Early film formation is a key advantage of electrolyte additives—the earlier the SEI film forms, the more it suppresses direct reactions between electrode materials and the electrolyte, reducing irreversible capacity loss. This is also the core reason why the initial coulombic efficiency (ICE) and initial capacity of the three derivatives are superior to those of the base group.
2. Basic Performance: ICE and initial capacity comprehensively superior to the base group
01 Initial Coulombic Efficiency (ICE):
ARC-S24 ≈ ARC-S20 > ARC-S28 > Base group, indicating that the derivatives can effectively reduce irreversible reactions during the initial charge-discharge cycles.
02 Initial Discharge Capacity:
The trend is consistent with ICE. All three derivatives outperform the base group, indicating an enhanced initial energy output capability.
Analysis: The improvement in ICE and initial capacity is directly related to early film formation—the early development of the SEI film suppresses the contact between solvent molecules and active materials, minimizing active material loss. This is crucial for practical battery applications (such as initial cell performance).
3. Rate Capability: Outstanding high-rate charging performance, with shortcomings in low-rate charging
01 Charging Performance:
① Low-rate (≤1/2C, e.g. 0.33C、0.5C): All three derivatives are inferior to the base group, with ARC-S20 performing the worst (over 4% lower than the base group).
② High-rate (≥2C, e.g. 2C、4C): All three derivatives outperform the base group, with ARC-S20 performing the best (over 8% higher than the base group).
Analysis: It is hypothesized that the SEI films formed by DTD derivatives possess better high-rate ionic conductivity, reducing polarization. Under low-rate conditions, however, ion migration kinetics are slower, failing to exhibit these advantages.
02 Discharging Performance:
① High-rate (≥3C): Little difference is observed among the four additives (including the base group), indicating comparable SEI film stability under high-rate discharge.
② Low-rate (≤1/2C）): The base group performs slightly better (more than 0.5% higher), echoing the low-rate charging trend, primarily due to the lower ohmic resistance of the base group's SEI film.
Analysis: Rate performance differences reflect the "dynamic adaptability" of the SEI film. The SEI films formed by ARC-S20 and other DTD derivatives are better suited for rapid ion migration at high rates, but their resistance disadvantages at low rates become prominent. Balancing high- and low-rate performance through electrolyte formulation optimization is required.
4. Extreme Condition Stability: ARC-S24 exhibits the best comprehensive performance
01 High-Temperature Storage (60℃，14d):
ARC-S24 performs best in capacity recovery rate, gas generation suppression (lowest thickness change rate, Δh of -1.48%), and voltage stability (small voltage drop).
The capacity retention rate （85.45%） is second only to ARC-S28 （87.20%）. The capacity recovery rate is optimal at 86.94%.
The internal resistance change rate is better than ARC-S20, but inferior to the base group and ARC-S28, indicating that the high-temperature and high-voltage stability of its SEI film still needs improvement.
02 High- and Low-Temperature Discharge:
① Low-temperature （-20~0℃）: ARC-S20, ARC-S28 show little difference from the base group, while ARC-S24 exhibits a slightly higher capacity retention rate of approximately 2%.
② High-temperature （55℃）: Little difference among the four additives, indicating convergent SEI film stability during high-temperature discharge.
03 High-Temperature Cycling（45℃）:
ARC-S24≈ARC-S28> Base group > ARC-S20. This indicates that the SEI films of the former two possess superior long-term anti-aging capabilities, whereas the film structure of ARC-S20 is prone to defects during cycling, which is detrimental to cycling performance.
IV. Comprehensive Performance Ranking and Application Scenario Matching
Based on the above analysis, the comprehensive performance of the three additives can be ranked as follows: ARC-S24 > ARC-S28 > ARC-S20. Recommended application scenarios are as follows:
ARC-S24: Suitable for scenarios demanding high comprehensive performance (ICE, high/low-temperature performance, high-temperature storage, and cycling stability), such as power batteries and energy storage batteries.
ARC-S28: Suitable for scenarios highlighting high-temperature storage capacity retention, such as energy storage equipment in high-temperature regions.
ARC-S20: Suitable for applications prioritizing high-rate charging requirements (such as fast-charging station ancillary batteries), but trade-offs regarding low-rate charging and high-temperature cycling shortcomings must be accepted.
V. Electrolyte Additive Optimization Suggestions
To address the shortcomings in low-rate charging performance and large high-temperature internal resistance growth:
Adjust Additive Concentration: Lower the addition amount of ARC-S20/S24/S28 (e.g., by 10%–20% from current ratios) to reduce SEI film thickness, lower resistance under low-rate conditions, and optimize the SEI film component structure.
Blend with Low-Resistance Additives: Blend with film-forming additives possessing low resistance to balance high- and low-rate performance.
VI. Evaluation Summary
Rolechem ' DTD derivative additives (especially ARC-S24) exhibit significant performance advantages in sodium-ion battery systems. Their early film-forming property is the core mechanism for enhancing initial efficiency and cycling stability. Through targeted optimization of low-rate performance and high-temperature internal resistance changes, such additives are expected to become key components in next-generation high-performance sodium-ion batteries.
