Negative Electrode Capacitance Tuning for High-Rate Secondary Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current secondary batteries face challenges in achieving high cycle life and rate performance due to issues like lithium precipitation and polarization, which are exacerbated by poor electrolyte solution infiltration and internal resistance increases.
Innovation Solution
The secondary battery design incorporates a negative electrode plate with a specific non-faradaic electric quantity (0.05≤Q≤2.5) and non-faradaic capacitance (0.5≤Cdl≤5 nF) to balance high-rate and charge/discharge characteristics, using materials like artificial graphite and a protective film layer to enhance compatibility with the electrolyte solution and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the negative electrode plate uses high capacity material, then the battery capacity increases, but the cycle life deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the non-faradaic electric quantity parameter (Q=Cdl×ΔU) within 0.05-2.5 C and non-faradaic capacitance (Cdl) within 0.5-5 nF. These parameter optimizations enable the negative electrode to achieve both high capacity utilization and long cycle stability by balancing the electric quantity characteristics
Solution Approach 2:
The patent employs composite materials by combining specific carbon materials (artificial graphite, natural graphite, soft carbon, hard carbon, amorphous carbon, carbon fiber, carbon nanotubes, or mesocarbon microspheres) with controlled particle size distributions (fine powder ≤2.2 μm and coarse powder ≥35 μm). This composite approach achieves both high capacity and excellent cycle performance
2Power
If the battery operates at high rate, then the power output increases, but the polarization increases
Solution Approach 1:
The patent reduces polarization through parameter changes by optimizing the non-faradaic capacitance (Cdl: 0.5-5 nF) and potential interval (ΔU: 0.1-0.5 V), which improve the electrode's charge/discharge characteristics and reduce interface resistance, thereby lowering polarization during high-rate operation
Solution Approach 2:
The patent applies local quality by creating a protective film layer on the negative electrode surface with specific properties (thickness H: 5-180 nm). This localized modification at the electrode-electrolyte interface improves ion transport and reduces polarization without affecting the bulk material properties
3Ease of manufacture
If the electrolyte solution infiltration is poor, then the manufacturing simplicity is maintained, but the lithium precipitation occurs
Solution Approach 1:
The patent prevents lithium precipitation through parameter changes by controlling the non-faradaic electric quantity (Q: 0.05-2.5 C) and adding lithium salt additives (LiBF4, LiBOB, LiPO2F2, LiTFSI, or LiFSI) at concentrations of 0.1%-2%. These parameter optimizations improve electrolyte infiltration and prevent lithium deposition
Solution Approach 2:
The patent introduces an intermediary protective film layer formed by lithium salt additives that mediates between the electrolyte and negative electrode. This film improves electrolyte infiltration and prevents direct contact between lithium ions and the electrode surface, avoiding precipitation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in improved consistency, long cycle life, and excellent rate performance by reducing interface deterioration and polarization, while maintaining high energy density and kinetic performance.
Implementation Method 1
non-faradaic capacitance Cdl nF of the negative electrode plate satisfies: 0.5≤Cdl≤5
Implementation Method 2
a resistance R mΩ of the negative electrode active material layer satisfies: 5≤R≤20
Data Source
AI summary
A secondary battery and an electrochemical device are provided. The secondary battery includes a positive electrode plate, a separator, an electrolyte solution, and a negative electrode plate. The negative electrode plate includes a negative electrode current collector, and a negative electrode active material layer disposed on the negative electrode current collector. Non-faradaic electric quantity Q C of the negative electrode plate satisfies: 0.05≤Q≤2.5, wherein Q=Cdl×ΔU, Cdl nF is non-faradaic capacitance of the negative electrode plate, and ΔU V is potential interval of the negative electrode active material layer.