Nonaqueous Battery Buffer Layer for Cycle Stability
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Solution Overview
Problem
Nonaqueous electrolyte batteries using niobium-and-titanium-containing composite oxides face poor charge-and-discharge cycle performance due to significant volume changes during charging and discharging, leading to increased internal resistance, capacity degradation, and potential short circuits.
Innovation Solution
Incorporating an intermediate region with a carbonaceous material and gel nonaqueous electrolyte between the negative electrode active material layer and the separator layer, which absorbs volume changes and maintains electronic conductivity, while the separator layer prevents direct contact between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If niobium-and-titanium-containing composite oxide is used as negative electrode active material to achieve larger capacity, then capacity increases, but volume change during charging and discharging causes deterioration in charge-and-discharge cycle performance
Solution Approach 1:
A buffer layer is introduced as an intermediary between the niobium-and-titanium-containing composite oxide negative electrode and the separator. This buffer layer absorbs the volume changes of the active material during charging and discharging, preventing direct mechanical stress on the electrode structure and maintaining stable charge-and-discharge cycle performance while preserving the high capacity benefits of the composite oxide material.
Solution Approach 2:
The negative electrode is designed as a composite structure combining niobium-and-titanium-containing composite oxide particles with a buffer material matrix. This composite configuration allows the active material to deliver high capacity while the buffer component accommodates volume expansion and contraction, resolving the contradiction between capacity and cycle stability.
2Quantity of substance
If niobium-and-titanium-containing composite oxide is used to achieve larger capacity, then capacity increases, but internal resistance increases due to volume changes
Solution Approach 1:
The buffer layer serves as a mediator that maintains stable electrical contact between the active material particles and the current collector throughout charge-and-discharge cycles. By absorbing volume changes, it prevents particle detachment and contact resistance increase, thereby maintaining low internal resistance while preserving high capacity.
3Quantity of substance
If niobium-and-titanium-containing composite oxide is used to achieve larger capacity, then capacity increases, but short circuits may occur due to volume changes
Solution Approach 1:
The buffer layer acts as a mechanical buffer that absorbs the expansion and contraction of the active material during cycling. This prevents the electrode from deforming excessively and coming into direct contact with the separator, thereby eliminating the short circuit risk while maintaining the high capacity advantages of the niobium-and-titanium-containing composite oxide.
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 configuration enhances cycle life performance by minimizing capacity loss and resistance increase, and preventing short circuits, thereby extending the battery's life and maintaining performance.
Implementation Method 1
an intermediate region which is located between the negative electrode active material layer and the separator layer, and includes a carbonaceous material, wherein at least a part of the gel nonaqueous electrolyte is held in the intermediate region
Implementation Method 2
a separator layer which is provided between the positive electrode and the negative electrode
Implementation Method 3
the secondary batteries are charged and discharged by, for example, the transfer of lithium ions between positive and negative electrodes
Data Source
AI summary
According to one embodiment, a nonaqueous electrolyte battery is provided. The nonaqueous electrolyte battery includes a positive electrode, a negative electrode including a negative electrode active material layer, a separator layer, an intermediate region, and a gel nonaqueous electrolyte. The separator layer and the intermediate region hold at least a part of the gel nonaqueous electrolyte. The nonaqueous electrolyte battery satisfies a volume ratio VA/VB of 5 or more. VA is a volume of the intermediate region. VB is an average volume of gaps among the particles of the niobium-and-titanium-containing composite oxide in the negative electrode active material layer.